blob: 5d8f496d624ed3ae77deed6e927801405155d9ea [file] [log] [blame]
Linus Torvalds1da177e2005-04-16 15:20:36 -07001/*
2 * linux/fs/buffer.c
3 *
4 * Copyright (C) 1991, 1992, 2002 Linus Torvalds
5 */
6
7/*
8 * Start bdflush() with kernel_thread not syscall - Paul Gortmaker, 12/95
9 *
10 * Removed a lot of unnecessary code and simplified things now that
11 * the buffer cache isn't our primary cache - Andrew Tridgell 12/96
12 *
13 * Speed up hash, lru, and free list operations. Use gfp() for allocating
14 * hash table, use SLAB cache for buffer heads. SMP threading. -DaveM
15 *
16 * Added 32k buffer block sizes - these are required older ARM systems. - RMK
17 *
18 * async buffer flushing, 1999 Andrea Arcangeli <andrea@suse.de>
19 */
20
Linus Torvalds1da177e2005-04-16 15:20:36 -070021#include <linux/kernel.h>
22#include <linux/syscalls.h>
23#include <linux/fs.h>
Christoph Hellwigae259a92016-06-21 09:23:11 +100024#include <linux/iomap.h>
Linus Torvalds1da177e2005-04-16 15:20:36 -070025#include <linux/mm.h>
26#include <linux/percpu.h>
27#include <linux/slab.h>
Randy Dunlap16f7e0f2006-01-11 12:17:46 -080028#include <linux/capability.h>
Linus Torvalds1da177e2005-04-16 15:20:36 -070029#include <linux/blkdev.h>
30#include <linux/file.h>
31#include <linux/quotaops.h>
32#include <linux/highmem.h>
Paul Gortmaker630d9c42011-11-16 23:57:37 -050033#include <linux/export.h>
Tejun Heobafc0db2015-06-02 08:37:23 -060034#include <linux/backing-dev.h>
Linus Torvalds1da177e2005-04-16 15:20:36 -070035#include <linux/writeback.h>
36#include <linux/hash.h>
37#include <linux/suspend.h>
38#include <linux/buffer_head.h>
Andrew Morton55e829a2006-12-10 02:19:27 -080039#include <linux/task_io_accounting_ops.h>
Linus Torvalds1da177e2005-04-16 15:20:36 -070040#include <linux/bio.h>
41#include <linux/notifier.h>
42#include <linux/cpu.h>
43#include <linux/bitops.h>
44#include <linux/mpage.h>
Ingo Molnarfb1c8f92005-09-10 00:25:56 -070045#include <linux/bit_spinlock.h>
Tejun Heo5305cb82013-01-11 13:06:36 -080046#include <trace/events/block.h>
Linus Torvalds1da177e2005-04-16 15:20:36 -070047
48static int fsync_buffers_list(spinlock_t *lock, struct list_head *list);
Mike Christie2a222ca2016-06-05 14:31:43 -050049static int submit_bh_wbc(int op, int op_flags, struct buffer_head *bh,
Tejun Heob16b1de2015-06-02 08:39:48 -060050 unsigned long bio_flags,
51 struct writeback_control *wbc);
Linus Torvalds1da177e2005-04-16 15:20:36 -070052
53#define BH_ENTRY(list) list_entry((list), struct buffer_head, b_assoc_buffers)
54
Yan Honga3f3c292012-12-12 13:52:15 -080055void init_buffer(struct buffer_head *bh, bh_end_io_t *handler, void *private)
Linus Torvalds1da177e2005-04-16 15:20:36 -070056{
57 bh->b_end_io = handler;
58 bh->b_private = private;
59}
H Hartley Sweeten1fe72ea2009-09-22 16:43:51 -070060EXPORT_SYMBOL(init_buffer);
Linus Torvalds1da177e2005-04-16 15:20:36 -070061
Tejun Heof0059af2013-01-11 13:06:35 -080062inline void touch_buffer(struct buffer_head *bh)
63{
Tejun Heo5305cb82013-01-11 13:06:36 -080064 trace_block_touch_buffer(bh);
Tejun Heof0059af2013-01-11 13:06:35 -080065 mark_page_accessed(bh->b_page);
66}
67EXPORT_SYMBOL(touch_buffer);
68
Harvey Harrisonfc9b52c2008-02-08 04:19:52 -080069void __lock_buffer(struct buffer_head *bh)
Linus Torvalds1da177e2005-04-16 15:20:36 -070070{
NeilBrown74316202014-07-07 15:16:04 +100071 wait_on_bit_lock_io(&bh->b_state, BH_Lock, TASK_UNINTERRUPTIBLE);
Linus Torvalds1da177e2005-04-16 15:20:36 -070072}
73EXPORT_SYMBOL(__lock_buffer);
74
Harvey Harrisonfc9b52c2008-02-08 04:19:52 -080075void unlock_buffer(struct buffer_head *bh)
Linus Torvalds1da177e2005-04-16 15:20:36 -070076{
Nick Piggin51b07fc2008-10-18 20:27:00 -070077 clear_bit_unlock(BH_Lock, &bh->b_state);
Peter Zijlstra4e857c52014-03-17 18:06:10 +010078 smp_mb__after_atomic();
Linus Torvalds1da177e2005-04-16 15:20:36 -070079 wake_up_bit(&bh->b_state, BH_Lock);
80}
H Hartley Sweeten1fe72ea2009-09-22 16:43:51 -070081EXPORT_SYMBOL(unlock_buffer);
Linus Torvalds1da177e2005-04-16 15:20:36 -070082
83/*
Mel Gormanb4597222013-07-03 15:02:05 -070084 * Returns if the page has dirty or writeback buffers. If all the buffers
85 * are unlocked and clean then the PageDirty information is stale. If
86 * any of the pages are locked, it is assumed they are locked for IO.
87 */
88void buffer_check_dirty_writeback(struct page *page,
89 bool *dirty, bool *writeback)
90{
91 struct buffer_head *head, *bh;
92 *dirty = false;
93 *writeback = false;
94
95 BUG_ON(!PageLocked(page));
96
97 if (!page_has_buffers(page))
98 return;
99
100 if (PageWriteback(page))
101 *writeback = true;
102
103 head = page_buffers(page);
104 bh = head;
105 do {
106 if (buffer_locked(bh))
107 *writeback = true;
108
109 if (buffer_dirty(bh))
110 *dirty = true;
111
112 bh = bh->b_this_page;
113 } while (bh != head);
114}
115EXPORT_SYMBOL(buffer_check_dirty_writeback);
116
117/*
Linus Torvalds1da177e2005-04-16 15:20:36 -0700118 * Block until a buffer comes unlocked. This doesn't stop it
119 * from becoming locked again - you have to lock it yourself
120 * if you want to preserve its state.
121 */
122void __wait_on_buffer(struct buffer_head * bh)
123{
NeilBrown74316202014-07-07 15:16:04 +1000124 wait_on_bit_io(&bh->b_state, BH_Lock, TASK_UNINTERRUPTIBLE);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700125}
H Hartley Sweeten1fe72ea2009-09-22 16:43:51 -0700126EXPORT_SYMBOL(__wait_on_buffer);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700127
128static void
129__clear_page_buffers(struct page *page)
130{
131 ClearPagePrivate(page);
Hugh Dickins4c21e2f2005-10-29 18:16:40 -0700132 set_page_private(page, 0);
Kirill A. Shutemov09cbfea2016-04-01 15:29:47 +0300133 put_page(page);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700134}
135
Robert Elliottb744c2a2014-10-21 13:55:09 -0600136static void buffer_io_error(struct buffer_head *bh, char *msg)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700137{
Robert Elliott432f16e2014-10-21 13:55:11 -0600138 if (!test_bit(BH_Quiet, &bh->b_state))
139 printk_ratelimited(KERN_ERR
Dmitry Monakhova1c6f0572015-04-13 16:31:37 +0400140 "Buffer I/O error on dev %pg, logical block %llu%s\n",
141 bh->b_bdev, (unsigned long long)bh->b_blocknr, msg);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700142}
143
144/*
Dmitry Monakhov68671f32007-10-16 01:24:47 -0700145 * End-of-IO handler helper function which does not touch the bh after
146 * unlocking it.
147 * Note: unlock_buffer() sort-of does touch the bh after unlocking it, but
148 * a race there is benign: unlock_buffer() only use the bh's address for
149 * hashing after unlocking the buffer, so it doesn't actually touch the bh
150 * itself.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700151 */
Dmitry Monakhov68671f32007-10-16 01:24:47 -0700152static void __end_buffer_read_notouch(struct buffer_head *bh, int uptodate)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700153{
154 if (uptodate) {
155 set_buffer_uptodate(bh);
156 } else {
Christoph Hellwig70246282016-07-19 11:28:41 +0200157 /* This happens, due to failed read-ahead attempts. */
Linus Torvalds1da177e2005-04-16 15:20:36 -0700158 clear_buffer_uptodate(bh);
159 }
160 unlock_buffer(bh);
Dmitry Monakhov68671f32007-10-16 01:24:47 -0700161}
162
163/*
164 * Default synchronous end-of-IO handler.. Just mark it up-to-date and
165 * unlock the buffer. This is what ll_rw_block uses too.
166 */
167void end_buffer_read_sync(struct buffer_head *bh, int uptodate)
168{
169 __end_buffer_read_notouch(bh, uptodate);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700170 put_bh(bh);
171}
H Hartley Sweeten1fe72ea2009-09-22 16:43:51 -0700172EXPORT_SYMBOL(end_buffer_read_sync);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700173
174void end_buffer_write_sync(struct buffer_head *bh, int uptodate)
175{
Linus Torvalds1da177e2005-04-16 15:20:36 -0700176 if (uptodate) {
177 set_buffer_uptodate(bh);
178 } else {
Robert Elliott432f16e2014-10-21 13:55:11 -0600179 buffer_io_error(bh, ", lost sync page write");
Linus Torvalds1da177e2005-04-16 15:20:36 -0700180 set_buffer_write_io_error(bh);
181 clear_buffer_uptodate(bh);
182 }
183 unlock_buffer(bh);
184 put_bh(bh);
185}
H Hartley Sweeten1fe72ea2009-09-22 16:43:51 -0700186EXPORT_SYMBOL(end_buffer_write_sync);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700187
188/*
Linus Torvalds1da177e2005-04-16 15:20:36 -0700189 * Various filesystems appear to want __find_get_block to be non-blocking.
190 * But it's the page lock which protects the buffers. To get around this,
191 * we get exclusion from try_to_free_buffers with the blockdev mapping's
192 * private_lock.
193 *
194 * Hack idea: for the blockdev mapping, i_bufferlist_lock contention
195 * may be quite high. This code could TryLock the page, and if that
196 * succeeds, there is no need to take private_lock. (But if
197 * private_lock is contended then so is mapping->tree_lock).
198 */
199static struct buffer_head *
Coywolf Qi Hunt385fd4c2005-11-07 00:59:39 -0800200__find_get_block_slow(struct block_device *bdev, sector_t block)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700201{
202 struct inode *bd_inode = bdev->bd_inode;
203 struct address_space *bd_mapping = bd_inode->i_mapping;
204 struct buffer_head *ret = NULL;
205 pgoff_t index;
206 struct buffer_head *bh;
207 struct buffer_head *head;
208 struct page *page;
209 int all_mapped = 1;
210
Kirill A. Shutemov09cbfea2016-04-01 15:29:47 +0300211 index = block >> (PAGE_SHIFT - bd_inode->i_blkbits);
Mel Gorman2457aec2014-06-04 16:10:31 -0700212 page = find_get_page_flags(bd_mapping, index, FGP_ACCESSED);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700213 if (!page)
214 goto out;
215
216 spin_lock(&bd_mapping->private_lock);
217 if (!page_has_buffers(page))
218 goto out_unlock;
219 head = page_buffers(page);
220 bh = head;
221 do {
Nikanth Karthikesan97f76d32009-04-02 16:56:46 -0700222 if (!buffer_mapped(bh))
223 all_mapped = 0;
224 else if (bh->b_blocknr == block) {
Linus Torvalds1da177e2005-04-16 15:20:36 -0700225 ret = bh;
226 get_bh(bh);
227 goto out_unlock;
228 }
Linus Torvalds1da177e2005-04-16 15:20:36 -0700229 bh = bh->b_this_page;
230 } while (bh != head);
231
232 /* we might be here because some of the buffers on this page are
233 * not mapped. This is due to various races between
234 * file io on the block device and getblk. It gets dealt with
235 * elsewhere, don't buffer_error if we had some unmapped buffers
236 */
237 if (all_mapped) {
238 printk("__find_get_block_slow() failed. "
239 "block=%llu, b_blocknr=%llu\n",
Badari Pulavarty205f87f2006-03-26 01:38:00 -0800240 (unsigned long long)block,
241 (unsigned long long)bh->b_blocknr);
242 printk("b_state=0x%08lx, b_size=%zu\n",
243 bh->b_state, bh->b_size);
Dmitry Monakhova1c6f0572015-04-13 16:31:37 +0400244 printk("device %pg blocksize: %d\n", bdev,
Tao Ma72a2ebd2011-10-31 17:09:00 -0700245 1 << bd_inode->i_blkbits);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700246 }
247out_unlock:
248 spin_unlock(&bd_mapping->private_lock);
Kirill A. Shutemov09cbfea2016-04-01 15:29:47 +0300249 put_page(page);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700250out:
251 return ret;
252}
253
Linus Torvalds1da177e2005-04-16 15:20:36 -0700254/*
Jens Axboe5b0830c2009-09-23 19:37:09 +0200255 * Kick the writeback threads then try to free up some ZONE_NORMAL memory.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700256 */
257static void free_more_memory(void)
258{
Mel Gormanc33d6c02016-05-19 17:14:10 -0700259 struct zoneref *z;
Mel Gorman0e884602008-04-28 02:12:14 -0700260 int nid;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700261
Curt Wohlgemuth0e175a12011-10-07 21:54:10 -0600262 wakeup_flusher_threads(1024, WB_REASON_FREE_MORE_MEM);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700263 yield();
264
Mel Gorman0e884602008-04-28 02:12:14 -0700265 for_each_online_node(nid) {
Mel Gormanc33d6c02016-05-19 17:14:10 -0700266
267 z = first_zones_zonelist(node_zonelist(nid, GFP_NOFS),
268 gfp_zone(GFP_NOFS), NULL);
269 if (z->zone)
Mel Gorman54a6eb52008-04-28 02:12:16 -0700270 try_to_free_pages(node_zonelist(nid, GFP_NOFS), 0,
KAMEZAWA Hiroyuki327c0e92009-03-31 15:23:31 -0700271 GFP_NOFS, NULL);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700272 }
273}
274
275/*
276 * I/O completion handler for block_read_full_page() - pages
277 * which come unlocked at the end of I/O.
278 */
279static void end_buffer_async_read(struct buffer_head *bh, int uptodate)
280{
Linus Torvalds1da177e2005-04-16 15:20:36 -0700281 unsigned long flags;
Nick Piggina3972202005-07-07 17:56:56 -0700282 struct buffer_head *first;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700283 struct buffer_head *tmp;
284 struct page *page;
285 int page_uptodate = 1;
286
287 BUG_ON(!buffer_async_read(bh));
288
289 page = bh->b_page;
290 if (uptodate) {
291 set_buffer_uptodate(bh);
292 } else {
293 clear_buffer_uptodate(bh);
Robert Elliott432f16e2014-10-21 13:55:11 -0600294 buffer_io_error(bh, ", async page read");
Linus Torvalds1da177e2005-04-16 15:20:36 -0700295 SetPageError(page);
296 }
297
298 /*
299 * Be _very_ careful from here on. Bad things can happen if
300 * two buffer heads end IO at almost the same time and both
301 * decide that the page is now completely done.
302 */
Nick Piggina3972202005-07-07 17:56:56 -0700303 first = page_buffers(page);
304 local_irq_save(flags);
305 bit_spin_lock(BH_Uptodate_Lock, &first->b_state);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700306 clear_buffer_async_read(bh);
307 unlock_buffer(bh);
308 tmp = bh;
309 do {
310 if (!buffer_uptodate(tmp))
311 page_uptodate = 0;
312 if (buffer_async_read(tmp)) {
313 BUG_ON(!buffer_locked(tmp));
314 goto still_busy;
315 }
316 tmp = tmp->b_this_page;
317 } while (tmp != bh);
Nick Piggina3972202005-07-07 17:56:56 -0700318 bit_spin_unlock(BH_Uptodate_Lock, &first->b_state);
319 local_irq_restore(flags);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700320
321 /*
322 * If none of the buffers had errors and they are all
323 * uptodate then we can set the page uptodate.
324 */
325 if (page_uptodate && !PageError(page))
326 SetPageUptodate(page);
327 unlock_page(page);
328 return;
329
330still_busy:
Nick Piggina3972202005-07-07 17:56:56 -0700331 bit_spin_unlock(BH_Uptodate_Lock, &first->b_state);
332 local_irq_restore(flags);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700333 return;
334}
335
336/*
337 * Completion handler for block_write_full_page() - pages which are unlocked
338 * during I/O, and which have PageWriteback cleared upon I/O completion.
339 */
Chris Mason35c80d52009-04-15 13:22:38 -0400340void end_buffer_async_write(struct buffer_head *bh, int uptodate)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700341{
Linus Torvalds1da177e2005-04-16 15:20:36 -0700342 unsigned long flags;
Nick Piggina3972202005-07-07 17:56:56 -0700343 struct buffer_head *first;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700344 struct buffer_head *tmp;
345 struct page *page;
346
347 BUG_ON(!buffer_async_write(bh));
348
349 page = bh->b_page;
350 if (uptodate) {
351 set_buffer_uptodate(bh);
352 } else {
Robert Elliott432f16e2014-10-21 13:55:11 -0600353 buffer_io_error(bh, ", lost async page write");
Michal Hocko5114a972016-10-11 13:56:01 -0700354 mapping_set_error(page->mapping, -EIO);
Jan Kara58ff4072006-10-17 00:10:19 -0700355 set_buffer_write_io_error(bh);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700356 clear_buffer_uptodate(bh);
357 SetPageError(page);
358 }
359
Nick Piggina3972202005-07-07 17:56:56 -0700360 first = page_buffers(page);
361 local_irq_save(flags);
362 bit_spin_lock(BH_Uptodate_Lock, &first->b_state);
363
Linus Torvalds1da177e2005-04-16 15:20:36 -0700364 clear_buffer_async_write(bh);
365 unlock_buffer(bh);
366 tmp = bh->b_this_page;
367 while (tmp != bh) {
368 if (buffer_async_write(tmp)) {
369 BUG_ON(!buffer_locked(tmp));
370 goto still_busy;
371 }
372 tmp = tmp->b_this_page;
373 }
Nick Piggina3972202005-07-07 17:56:56 -0700374 bit_spin_unlock(BH_Uptodate_Lock, &first->b_state);
375 local_irq_restore(flags);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700376 end_page_writeback(page);
377 return;
378
379still_busy:
Nick Piggina3972202005-07-07 17:56:56 -0700380 bit_spin_unlock(BH_Uptodate_Lock, &first->b_state);
381 local_irq_restore(flags);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700382 return;
383}
H Hartley Sweeten1fe72ea2009-09-22 16:43:51 -0700384EXPORT_SYMBOL(end_buffer_async_write);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700385
386/*
387 * If a page's buffers are under async readin (end_buffer_async_read
388 * completion) then there is a possibility that another thread of
389 * control could lock one of the buffers after it has completed
390 * but while some of the other buffers have not completed. This
391 * locked buffer would confuse end_buffer_async_read() into not unlocking
392 * the page. So the absence of BH_Async_Read tells end_buffer_async_read()
393 * that this buffer is not under async I/O.
394 *
395 * The page comes unlocked when it has no locked buffer_async buffers
396 * left.
397 *
398 * PageLocked prevents anyone starting new async I/O reads any of
399 * the buffers.
400 *
401 * PageWriteback is used to prevent simultaneous writeout of the same
402 * page.
403 *
404 * PageLocked prevents anyone from starting writeback of a page which is
405 * under read I/O (PageWriteback is only ever set against a locked page).
406 */
407static void mark_buffer_async_read(struct buffer_head *bh)
408{
409 bh->b_end_io = end_buffer_async_read;
410 set_buffer_async_read(bh);
411}
412
H Hartley Sweeten1fe72ea2009-09-22 16:43:51 -0700413static void mark_buffer_async_write_endio(struct buffer_head *bh,
414 bh_end_io_t *handler)
Chris Mason35c80d52009-04-15 13:22:38 -0400415{
416 bh->b_end_io = handler;
417 set_buffer_async_write(bh);
418}
419
Linus Torvalds1da177e2005-04-16 15:20:36 -0700420void mark_buffer_async_write(struct buffer_head *bh)
421{
Chris Mason35c80d52009-04-15 13:22:38 -0400422 mark_buffer_async_write_endio(bh, end_buffer_async_write);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700423}
424EXPORT_SYMBOL(mark_buffer_async_write);
425
426
427/*
428 * fs/buffer.c contains helper functions for buffer-backed address space's
429 * fsync functions. A common requirement for buffer-based filesystems is
430 * that certain data from the backing blockdev needs to be written out for
431 * a successful fsync(). For example, ext2 indirect blocks need to be
432 * written back and waited upon before fsync() returns.
433 *
434 * The functions mark_buffer_inode_dirty(), fsync_inode_buffers(),
435 * inode_has_buffers() and invalidate_inode_buffers() are provided for the
436 * management of a list of dependent buffers at ->i_mapping->private_list.
437 *
438 * Locking is a little subtle: try_to_free_buffers() will remove buffers
439 * from their controlling inode's queue when they are being freed. But
440 * try_to_free_buffers() will be operating against the *blockdev* mapping
441 * at the time, not against the S_ISREG file which depends on those buffers.
442 * So the locking for private_list is via the private_lock in the address_space
443 * which backs the buffers. Which is different from the address_space
444 * against which the buffers are listed. So for a particular address_space,
445 * mapping->private_lock does *not* protect mapping->private_list! In fact,
446 * mapping->private_list will always be protected by the backing blockdev's
447 * ->private_lock.
448 *
449 * Which introduces a requirement: all buffers on an address_space's
450 * ->private_list must be from the same address_space: the blockdev's.
451 *
452 * address_spaces which do not place buffers at ->private_list via these
453 * utility functions are free to use private_lock and private_list for
454 * whatever they want. The only requirement is that list_empty(private_list)
455 * be true at clear_inode() time.
456 *
457 * FIXME: clear_inode should not call invalidate_inode_buffers(). The
458 * filesystems should do that. invalidate_inode_buffers() should just go
459 * BUG_ON(!list_empty).
460 *
461 * FIXME: mark_buffer_dirty_inode() is a data-plane operation. It should
462 * take an address_space, not an inode. And it should be called
463 * mark_buffer_dirty_fsync() to clearly define why those buffers are being
464 * queued up.
465 *
466 * FIXME: mark_buffer_dirty_inode() doesn't need to add the buffer to the
467 * list if it is already on a list. Because if the buffer is on a list,
468 * it *must* already be on the right one. If not, the filesystem is being
469 * silly. This will save a ton of locking. But first we have to ensure
470 * that buffers are taken *off* the old inode's list when they are freed
471 * (presumably in truncate). That requires careful auditing of all
472 * filesystems (do it inside bforget()). It could also be done by bringing
473 * b_inode back.
474 */
475
476/*
477 * The buffer's backing address_space's private_lock must be held
478 */
Thomas Petazzonidbacefc2008-07-29 22:33:47 -0700479static void __remove_assoc_queue(struct buffer_head *bh)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700480{
481 list_del_init(&bh->b_assoc_buffers);
Jan Kara58ff4072006-10-17 00:10:19 -0700482 WARN_ON(!bh->b_assoc_map);
483 if (buffer_write_io_error(bh))
484 set_bit(AS_EIO, &bh->b_assoc_map->flags);
485 bh->b_assoc_map = NULL;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700486}
487
488int inode_has_buffers(struct inode *inode)
489{
490 return !list_empty(&inode->i_data.private_list);
491}
492
493/*
494 * osync is designed to support O_SYNC io. It waits synchronously for
495 * all already-submitted IO to complete, but does not queue any new
496 * writes to the disk.
497 *
498 * To do O_SYNC writes, just queue the buffer writes with ll_rw_block as
499 * you dirty the buffers, and then use osync_inode_buffers to wait for
500 * completion. Any other dirty buffers which are not yet queued for
501 * write will not be flushed to disk by the osync.
502 */
503static int osync_buffers_list(spinlock_t *lock, struct list_head *list)
504{
505 struct buffer_head *bh;
506 struct list_head *p;
507 int err = 0;
508
509 spin_lock(lock);
510repeat:
511 list_for_each_prev(p, list) {
512 bh = BH_ENTRY(p);
513 if (buffer_locked(bh)) {
514 get_bh(bh);
515 spin_unlock(lock);
516 wait_on_buffer(bh);
517 if (!buffer_uptodate(bh))
518 err = -EIO;
519 brelse(bh);
520 spin_lock(lock);
521 goto repeat;
522 }
523 }
524 spin_unlock(lock);
525 return err;
526}
527
Al Viro01a05b32010-03-23 06:06:58 -0400528static void do_thaw_one(struct super_block *sb, void *unused)
529{
Al Viro01a05b32010-03-23 06:06:58 -0400530 while (sb->s_bdev && !thaw_bdev(sb->s_bdev, sb))
Dmitry Monakhova1c6f0572015-04-13 16:31:37 +0400531 printk(KERN_WARNING "Emergency Thaw on %pg\n", sb->s_bdev);
Al Viro01a05b32010-03-23 06:06:58 -0400532}
533
H Hartley Sweeten1fe72ea2009-09-22 16:43:51 -0700534static void do_thaw_all(struct work_struct *work)
Eric Sandeenc2d75432009-03-31 15:23:46 -0700535{
Al Viro01a05b32010-03-23 06:06:58 -0400536 iterate_supers(do_thaw_one, NULL);
Jens Axboe053c5252009-04-08 13:44:08 +0200537 kfree(work);
Eric Sandeenc2d75432009-03-31 15:23:46 -0700538 printk(KERN_WARNING "Emergency Thaw complete\n");
539}
540
541/**
542 * emergency_thaw_all -- forcibly thaw every frozen filesystem
543 *
544 * Used for emergency unfreeze of all filesystems via SysRq
545 */
546void emergency_thaw_all(void)
547{
Jens Axboe053c5252009-04-08 13:44:08 +0200548 struct work_struct *work;
549
550 work = kmalloc(sizeof(*work), GFP_ATOMIC);
551 if (work) {
552 INIT_WORK(work, do_thaw_all);
553 schedule_work(work);
554 }
Eric Sandeenc2d75432009-03-31 15:23:46 -0700555}
556
Linus Torvalds1da177e2005-04-16 15:20:36 -0700557/**
Randy Dunlap78a4a502008-02-29 22:02:31 -0800558 * sync_mapping_buffers - write out & wait upon a mapping's "associated" buffers
Martin Waitz67be2dd2005-05-01 08:59:26 -0700559 * @mapping: the mapping which wants those buffers written
Linus Torvalds1da177e2005-04-16 15:20:36 -0700560 *
561 * Starts I/O against the buffers at mapping->private_list, and waits upon
562 * that I/O.
563 *
Martin Waitz67be2dd2005-05-01 08:59:26 -0700564 * Basically, this is a convenience function for fsync().
565 * @mapping is a file or directory which needs those buffers to be written for
566 * a successful fsync().
Linus Torvalds1da177e2005-04-16 15:20:36 -0700567 */
568int sync_mapping_buffers(struct address_space *mapping)
569{
Rafael Aquini252aa6f2012-12-11 16:02:35 -0800570 struct address_space *buffer_mapping = mapping->private_data;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700571
572 if (buffer_mapping == NULL || list_empty(&mapping->private_list))
573 return 0;
574
575 return fsync_buffers_list(&buffer_mapping->private_lock,
576 &mapping->private_list);
577}
578EXPORT_SYMBOL(sync_mapping_buffers);
579
580/*
581 * Called when we've recently written block `bblock', and it is known that
582 * `bblock' was for a buffer_boundary() buffer. This means that the block at
583 * `bblock + 1' is probably a dirty indirect block. Hunt it down and, if it's
584 * dirty, schedule it for IO. So that indirects merge nicely with their data.
585 */
586void write_boundary_block(struct block_device *bdev,
587 sector_t bblock, unsigned blocksize)
588{
589 struct buffer_head *bh = __find_get_block(bdev, bblock + 1, blocksize);
590 if (bh) {
591 if (buffer_dirty(bh))
Mike Christiedfec8a12016-06-05 14:31:44 -0500592 ll_rw_block(REQ_OP_WRITE, 0, 1, &bh);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700593 put_bh(bh);
594 }
595}
596
597void mark_buffer_dirty_inode(struct buffer_head *bh, struct inode *inode)
598{
599 struct address_space *mapping = inode->i_mapping;
600 struct address_space *buffer_mapping = bh->b_page->mapping;
601
602 mark_buffer_dirty(bh);
Rafael Aquini252aa6f2012-12-11 16:02:35 -0800603 if (!mapping->private_data) {
604 mapping->private_data = buffer_mapping;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700605 } else {
Rafael Aquini252aa6f2012-12-11 16:02:35 -0800606 BUG_ON(mapping->private_data != buffer_mapping);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700607 }
Jan Kara535ee2f2008-02-08 04:21:59 -0800608 if (!bh->b_assoc_map) {
Linus Torvalds1da177e2005-04-16 15:20:36 -0700609 spin_lock(&buffer_mapping->private_lock);
610 list_move_tail(&bh->b_assoc_buffers,
611 &mapping->private_list);
Jan Kara58ff4072006-10-17 00:10:19 -0700612 bh->b_assoc_map = mapping;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700613 spin_unlock(&buffer_mapping->private_lock);
614 }
615}
616EXPORT_SYMBOL(mark_buffer_dirty_inode);
617
618/*
Nick Piggin787d2212007-07-17 04:03:34 -0700619 * Mark the page dirty, and set it dirty in the radix tree, and mark the inode
620 * dirty.
621 *
622 * If warn is true, then emit a warning if the page is not uptodate and has
623 * not been truncated.
Greg Thelenc4843a72015-05-22 17:13:16 -0400624 *
Johannes Weiner81f8c3a2016-03-15 14:57:04 -0700625 * The caller must hold lock_page_memcg().
Nick Piggin787d2212007-07-17 04:03:34 -0700626 */
Greg Thelenc4843a72015-05-22 17:13:16 -0400627static void __set_page_dirty(struct page *page, struct address_space *mapping,
Johannes Weiner62cccb82016-03-15 14:57:22 -0700628 int warn)
Nick Piggin787d2212007-07-17 04:03:34 -0700629{
KOSAKI Motohiro227d53b32014-02-06 12:04:28 -0800630 unsigned long flags;
631
632 spin_lock_irqsave(&mapping->tree_lock, flags);
Nick Piggin787d2212007-07-17 04:03:34 -0700633 if (page->mapping) { /* Race with truncate? */
634 WARN_ON_ONCE(warn && !PageUptodate(page));
Johannes Weiner62cccb82016-03-15 14:57:22 -0700635 account_page_dirtied(page, mapping);
Nick Piggin787d2212007-07-17 04:03:34 -0700636 radix_tree_tag_set(&mapping->page_tree,
637 page_index(page), PAGECACHE_TAG_DIRTY);
638 }
KOSAKI Motohiro227d53b32014-02-06 12:04:28 -0800639 spin_unlock_irqrestore(&mapping->tree_lock, flags);
Nick Piggin787d2212007-07-17 04:03:34 -0700640}
641
642/*
Linus Torvalds1da177e2005-04-16 15:20:36 -0700643 * Add a page to the dirty page list.
644 *
645 * It is a sad fact of life that this function is called from several places
646 * deeply under spinlocking. It may not sleep.
647 *
648 * If the page has buffers, the uptodate buffers are set dirty, to preserve
649 * dirty-state coherency between the page and the buffers. It the page does
650 * not have buffers then when they are later attached they will all be set
651 * dirty.
652 *
653 * The buffers are dirtied before the page is dirtied. There's a small race
654 * window in which a writepage caller may see the page cleanness but not the
655 * buffer dirtiness. That's fine. If this code were to set the page dirty
656 * before the buffers, a concurrent writepage caller could clear the page dirty
657 * bit, see a bunch of clean buffers and we'd end up with dirty buffers/clean
658 * page on the dirty page list.
659 *
660 * We use private_lock to lock against try_to_free_buffers while using the
661 * page's buffer list. Also use this to protect against clean buffers being
662 * added to the page after it was set dirty.
663 *
664 * FIXME: may need to call ->reservepage here as well. That's rather up to the
665 * address_space though.
666 */
667int __set_page_dirty_buffers(struct page *page)
668{
Linus Torvaldsa8e7d492009-03-19 11:32:05 -0700669 int newly_dirty;
Nick Piggin787d2212007-07-17 04:03:34 -0700670 struct address_space *mapping = page_mapping(page);
Nick Pigginebf7a222006-10-10 04:36:54 +0200671
672 if (unlikely(!mapping))
673 return !TestSetPageDirty(page);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700674
675 spin_lock(&mapping->private_lock);
676 if (page_has_buffers(page)) {
677 struct buffer_head *head = page_buffers(page);
678 struct buffer_head *bh = head;
679
680 do {
681 set_buffer_dirty(bh);
682 bh = bh->b_this_page;
683 } while (bh != head);
684 }
Greg Thelenc4843a72015-05-22 17:13:16 -0400685 /*
Johannes Weiner81f8c3a2016-03-15 14:57:04 -0700686 * Lock out page->mem_cgroup migration to keep PageDirty
687 * synchronized with per-memcg dirty page counters.
Greg Thelenc4843a72015-05-22 17:13:16 -0400688 */
Johannes Weiner62cccb82016-03-15 14:57:22 -0700689 lock_page_memcg(page);
Linus Torvaldsa8e7d492009-03-19 11:32:05 -0700690 newly_dirty = !TestSetPageDirty(page);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700691 spin_unlock(&mapping->private_lock);
692
Linus Torvaldsa8e7d492009-03-19 11:32:05 -0700693 if (newly_dirty)
Johannes Weiner62cccb82016-03-15 14:57:22 -0700694 __set_page_dirty(page, mapping, 1);
Greg Thelenc4843a72015-05-22 17:13:16 -0400695
Johannes Weiner62cccb82016-03-15 14:57:22 -0700696 unlock_page_memcg(page);
Greg Thelenc4843a72015-05-22 17:13:16 -0400697
698 if (newly_dirty)
699 __mark_inode_dirty(mapping->host, I_DIRTY_PAGES);
700
Linus Torvaldsa8e7d492009-03-19 11:32:05 -0700701 return newly_dirty;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700702}
703EXPORT_SYMBOL(__set_page_dirty_buffers);
704
705/*
706 * Write out and wait upon a list of buffers.
707 *
708 * We have conflicting pressures: we want to make sure that all
709 * initially dirty buffers get waited on, but that any subsequently
710 * dirtied buffers don't. After all, we don't want fsync to last
711 * forever if somebody is actively writing to the file.
712 *
713 * Do this in two main stages: first we copy dirty buffers to a
714 * temporary inode list, queueing the writes as we go. Then we clean
715 * up, waiting for those writes to complete.
716 *
717 * During this second stage, any subsequent updates to the file may end
718 * up refiling the buffer on the original inode's dirty list again, so
719 * there is a chance we will end up with a buffer queued for write but
720 * not yet completed on that list. So, as a final cleanup we go through
721 * the osync code to catch these locked, dirty buffers without requeuing
722 * any newly dirty buffers for write.
723 */
724static int fsync_buffers_list(spinlock_t *lock, struct list_head *list)
725{
726 struct buffer_head *bh;
727 struct list_head tmp;
Jens Axboe7eaceac2011-03-10 08:52:07 +0100728 struct address_space *mapping;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700729 int err = 0, err2;
Jens Axboe4ee24912011-03-17 10:51:40 +0100730 struct blk_plug plug;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700731
732 INIT_LIST_HEAD(&tmp);
Jens Axboe4ee24912011-03-17 10:51:40 +0100733 blk_start_plug(&plug);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700734
735 spin_lock(lock);
736 while (!list_empty(list)) {
737 bh = BH_ENTRY(list->next);
Jan Kara535ee2f2008-02-08 04:21:59 -0800738 mapping = bh->b_assoc_map;
Jan Kara58ff4072006-10-17 00:10:19 -0700739 __remove_assoc_queue(bh);
Jan Kara535ee2f2008-02-08 04:21:59 -0800740 /* Avoid race with mark_buffer_dirty_inode() which does
741 * a lockless check and we rely on seeing the dirty bit */
742 smp_mb();
Linus Torvalds1da177e2005-04-16 15:20:36 -0700743 if (buffer_dirty(bh) || buffer_locked(bh)) {
744 list_add(&bh->b_assoc_buffers, &tmp);
Jan Kara535ee2f2008-02-08 04:21:59 -0800745 bh->b_assoc_map = mapping;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700746 if (buffer_dirty(bh)) {
747 get_bh(bh);
748 spin_unlock(lock);
749 /*
750 * Ensure any pending I/O completes so that
Christoph Hellwig9cb569d2010-08-11 17:06:24 +0200751 * write_dirty_buffer() actually writes the
752 * current contents - it is a noop if I/O is
753 * still in flight on potentially older
754 * contents.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700755 */
Jens Axboe721a9602011-03-09 11:56:30 +0100756 write_dirty_buffer(bh, WRITE_SYNC);
Jens Axboe9cf6b722009-04-06 14:48:03 +0200757
758 /*
759 * Kick off IO for the previous mapping. Note
760 * that we will not run the very last mapping,
761 * wait_on_buffer() will do that for us
762 * through sync_buffer().
763 */
Linus Torvalds1da177e2005-04-16 15:20:36 -0700764 brelse(bh);
765 spin_lock(lock);
766 }
767 }
768 }
769
Jens Axboe4ee24912011-03-17 10:51:40 +0100770 spin_unlock(lock);
771 blk_finish_plug(&plug);
772 spin_lock(lock);
773
Linus Torvalds1da177e2005-04-16 15:20:36 -0700774 while (!list_empty(&tmp)) {
775 bh = BH_ENTRY(tmp.prev);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700776 get_bh(bh);
Jan Kara535ee2f2008-02-08 04:21:59 -0800777 mapping = bh->b_assoc_map;
778 __remove_assoc_queue(bh);
779 /* Avoid race with mark_buffer_dirty_inode() which does
780 * a lockless check and we rely on seeing the dirty bit */
781 smp_mb();
782 if (buffer_dirty(bh)) {
783 list_add(&bh->b_assoc_buffers,
Jan Karae3892292008-03-04 14:28:33 -0800784 &mapping->private_list);
Jan Kara535ee2f2008-02-08 04:21:59 -0800785 bh->b_assoc_map = mapping;
786 }
Linus Torvalds1da177e2005-04-16 15:20:36 -0700787 spin_unlock(lock);
788 wait_on_buffer(bh);
789 if (!buffer_uptodate(bh))
790 err = -EIO;
791 brelse(bh);
792 spin_lock(lock);
793 }
794
795 spin_unlock(lock);
796 err2 = osync_buffers_list(lock, list);
797 if (err)
798 return err;
799 else
800 return err2;
801}
802
803/*
804 * Invalidate any and all dirty buffers on a given inode. We are
805 * probably unmounting the fs, but that doesn't mean we have already
806 * done a sync(). Just drop the buffers from the inode list.
807 *
808 * NOTE: we take the inode's blockdev's mapping's private_lock. Which
809 * assumes that all the buffers are against the blockdev. Not true
810 * for reiserfs.
811 */
812void invalidate_inode_buffers(struct inode *inode)
813{
814 if (inode_has_buffers(inode)) {
815 struct address_space *mapping = &inode->i_data;
816 struct list_head *list = &mapping->private_list;
Rafael Aquini252aa6f2012-12-11 16:02:35 -0800817 struct address_space *buffer_mapping = mapping->private_data;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700818
819 spin_lock(&buffer_mapping->private_lock);
820 while (!list_empty(list))
821 __remove_assoc_queue(BH_ENTRY(list->next));
822 spin_unlock(&buffer_mapping->private_lock);
823 }
824}
Jan Kara52b19ac2008-09-23 18:24:08 +0200825EXPORT_SYMBOL(invalidate_inode_buffers);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700826
827/*
828 * Remove any clean buffers from the inode's buffer list. This is called
829 * when we're trying to free the inode itself. Those buffers can pin it.
830 *
831 * Returns true if all buffers were removed.
832 */
833int remove_inode_buffers(struct inode *inode)
834{
835 int ret = 1;
836
837 if (inode_has_buffers(inode)) {
838 struct address_space *mapping = &inode->i_data;
839 struct list_head *list = &mapping->private_list;
Rafael Aquini252aa6f2012-12-11 16:02:35 -0800840 struct address_space *buffer_mapping = mapping->private_data;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700841
842 spin_lock(&buffer_mapping->private_lock);
843 while (!list_empty(list)) {
844 struct buffer_head *bh = BH_ENTRY(list->next);
845 if (buffer_dirty(bh)) {
846 ret = 0;
847 break;
848 }
849 __remove_assoc_queue(bh);
850 }
851 spin_unlock(&buffer_mapping->private_lock);
852 }
853 return ret;
854}
855
856/*
857 * Create the appropriate buffers when given a page for data area and
858 * the size of each buffer.. Use the bh->b_this_page linked list to
859 * follow the buffers created. Return NULL if unable to create more
860 * buffers.
861 *
862 * The retry flag is used to differentiate async IO (paging, swapping)
863 * which may not fail from ordinary buffer allocations.
864 */
865struct buffer_head *alloc_page_buffers(struct page *page, unsigned long size,
866 int retry)
867{
868 struct buffer_head *bh, *head;
869 long offset;
870
871try_again:
872 head = NULL;
873 offset = PAGE_SIZE;
874 while ((offset -= size) >= 0) {
875 bh = alloc_buffer_head(GFP_NOFS);
876 if (!bh)
877 goto no_grow;
878
Linus Torvalds1da177e2005-04-16 15:20:36 -0700879 bh->b_this_page = head;
880 bh->b_blocknr = -1;
881 head = bh;
882
Linus Torvalds1da177e2005-04-16 15:20:36 -0700883 bh->b_size = size;
884
885 /* Link the buffer to its page */
886 set_bh_page(bh, page, offset);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700887 }
888 return head;
889/*
890 * In case anything failed, we just free everything we got.
891 */
892no_grow:
893 if (head) {
894 do {
895 bh = head;
896 head = head->b_this_page;
897 free_buffer_head(bh);
898 } while (head);
899 }
900
901 /*
902 * Return failure for non-async IO requests. Async IO requests
903 * are not allowed to fail, so we have to wait until buffer heads
904 * become available. But we don't want tasks sleeping with
905 * partially complete buffers, so all were released above.
906 */
907 if (!retry)
908 return NULL;
909
910 /* We're _really_ low on memory. Now we just
911 * wait for old buffer heads to become free due to
912 * finishing IO. Since this is an async request and
913 * the reserve list is empty, we're sure there are
914 * async buffer heads in use.
915 */
916 free_more_memory();
917 goto try_again;
918}
919EXPORT_SYMBOL_GPL(alloc_page_buffers);
920
921static inline void
922link_dev_buffers(struct page *page, struct buffer_head *head)
923{
924 struct buffer_head *bh, *tail;
925
926 bh = head;
927 do {
928 tail = bh;
929 bh = bh->b_this_page;
930 } while (bh);
931 tail->b_this_page = head;
932 attach_page_buffers(page, head);
933}
934
Linus Torvaldsbbec02702012-11-29 12:31:52 -0800935static sector_t blkdev_max_block(struct block_device *bdev, unsigned int size)
936{
937 sector_t retval = ~((sector_t)0);
938 loff_t sz = i_size_read(bdev->bd_inode);
939
940 if (sz) {
941 unsigned int sizebits = blksize_bits(size);
942 retval = (sz >> sizebits);
943 }
944 return retval;
945}
946
Linus Torvalds1da177e2005-04-16 15:20:36 -0700947/*
948 * Initialise the state of a blockdev page's buffers.
949 */
Hugh Dickins676ce6d2012-08-23 12:17:36 +0200950static sector_t
Linus Torvalds1da177e2005-04-16 15:20:36 -0700951init_page_buffers(struct page *page, struct block_device *bdev,
952 sector_t block, int size)
953{
954 struct buffer_head *head = page_buffers(page);
955 struct buffer_head *bh = head;
956 int uptodate = PageUptodate(page);
Linus Torvaldsbbec02702012-11-29 12:31:52 -0800957 sector_t end_block = blkdev_max_block(I_BDEV(bdev->bd_inode), size);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700958
959 do {
960 if (!buffer_mapped(bh)) {
961 init_buffer(bh, NULL, NULL);
962 bh->b_bdev = bdev;
963 bh->b_blocknr = block;
964 if (uptodate)
965 set_buffer_uptodate(bh);
Jeff Moyer080399a2012-05-11 16:34:10 +0200966 if (block < end_block)
967 set_buffer_mapped(bh);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700968 }
969 block++;
970 bh = bh->b_this_page;
971 } while (bh != head);
Hugh Dickins676ce6d2012-08-23 12:17:36 +0200972
973 /*
974 * Caller needs to validate requested block against end of device.
975 */
976 return end_block;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700977}
978
979/*
980 * Create the page-cache page that contains the requested block.
981 *
Hugh Dickins676ce6d2012-08-23 12:17:36 +0200982 * This is used purely for blockdev mappings.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700983 */
Hugh Dickins676ce6d2012-08-23 12:17:36 +0200984static int
Linus Torvalds1da177e2005-04-16 15:20:36 -0700985grow_dev_page(struct block_device *bdev, sector_t block,
Gioh Kim3b5e6452014-09-04 22:04:42 -0400986 pgoff_t index, int size, int sizebits, gfp_t gfp)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700987{
988 struct inode *inode = bdev->bd_inode;
989 struct page *page;
990 struct buffer_head *bh;
Hugh Dickins676ce6d2012-08-23 12:17:36 +0200991 sector_t end_block;
992 int ret = 0; /* Will call free_more_memory() */
Johannes Weiner84235de2013-10-16 13:47:00 -0700993 gfp_t gfp_mask;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700994
Michal Hockoc62d2552015-11-06 16:28:49 -0800995 gfp_mask = mapping_gfp_constraint(inode->i_mapping, ~__GFP_FS) | gfp;
Gioh Kim3b5e6452014-09-04 22:04:42 -0400996
Johannes Weiner84235de2013-10-16 13:47:00 -0700997 /*
998 * XXX: __getblk_slow() can not really deal with failure and
999 * will endlessly loop on improvised global reclaim. Prefer
1000 * looping in the allocator rather than here, at least that
1001 * code knows what it's doing.
1002 */
1003 gfp_mask |= __GFP_NOFAIL;
1004
1005 page = find_or_create_page(inode->i_mapping, index, gfp_mask);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001006 if (!page)
Hugh Dickins676ce6d2012-08-23 12:17:36 +02001007 return ret;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001008
Eric Sesterhenne827f922006-03-26 18:24:46 +02001009 BUG_ON(!PageLocked(page));
Linus Torvalds1da177e2005-04-16 15:20:36 -07001010
1011 if (page_has_buffers(page)) {
1012 bh = page_buffers(page);
1013 if (bh->b_size == size) {
Hugh Dickins676ce6d2012-08-23 12:17:36 +02001014 end_block = init_page_buffers(page, bdev,
Anton Altaparmakovf2d5a942014-09-22 01:53:03 +01001015 (sector_t)index << sizebits,
1016 size);
Hugh Dickins676ce6d2012-08-23 12:17:36 +02001017 goto done;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001018 }
1019 if (!try_to_free_buffers(page))
1020 goto failed;
1021 }
1022
1023 /*
1024 * Allocate some buffers for this page
1025 */
1026 bh = alloc_page_buffers(page, size, 0);
1027 if (!bh)
1028 goto failed;
1029
1030 /*
1031 * Link the page to the buffers and initialise them. Take the
1032 * lock to be atomic wrt __find_get_block(), which does not
1033 * run under the page lock.
1034 */
1035 spin_lock(&inode->i_mapping->private_lock);
1036 link_dev_buffers(page, bh);
Anton Altaparmakovf2d5a942014-09-22 01:53:03 +01001037 end_block = init_page_buffers(page, bdev, (sector_t)index << sizebits,
1038 size);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001039 spin_unlock(&inode->i_mapping->private_lock);
Hugh Dickins676ce6d2012-08-23 12:17:36 +02001040done:
1041 ret = (block < end_block) ? 1 : -ENXIO;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001042failed:
Linus Torvalds1da177e2005-04-16 15:20:36 -07001043 unlock_page(page);
Kirill A. Shutemov09cbfea2016-04-01 15:29:47 +03001044 put_page(page);
Hugh Dickins676ce6d2012-08-23 12:17:36 +02001045 return ret;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001046}
1047
1048/*
1049 * Create buffers for the specified block device block's page. If
1050 * that page was dirty, the buffers are set dirty also.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001051 */
Arjan van de Ven858119e2006-01-14 13:20:43 -08001052static int
Gioh Kim3b5e6452014-09-04 22:04:42 -04001053grow_buffers(struct block_device *bdev, sector_t block, int size, gfp_t gfp)
Linus Torvalds1da177e2005-04-16 15:20:36 -07001054{
Linus Torvalds1da177e2005-04-16 15:20:36 -07001055 pgoff_t index;
1056 int sizebits;
1057
1058 sizebits = -1;
1059 do {
1060 sizebits++;
1061 } while ((size << sizebits) < PAGE_SIZE);
1062
1063 index = block >> sizebits;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001064
Andrew Mortone5657932006-10-11 01:21:46 -07001065 /*
1066 * Check for a block which wants to lie outside our maximum possible
1067 * pagecache index. (this comparison is done using sector_t types).
1068 */
1069 if (unlikely(index != block >> sizebits)) {
Andrew Mortone5657932006-10-11 01:21:46 -07001070 printk(KERN_ERR "%s: requested out-of-range block %llu for "
Dmitry Monakhova1c6f0572015-04-13 16:31:37 +04001071 "device %pg\n",
Harvey Harrison8e24eea2008-04-30 00:55:09 -07001072 __func__, (unsigned long long)block,
Dmitry Monakhova1c6f0572015-04-13 16:31:37 +04001073 bdev);
Andrew Mortone5657932006-10-11 01:21:46 -07001074 return -EIO;
1075 }
Hugh Dickins676ce6d2012-08-23 12:17:36 +02001076
Linus Torvalds1da177e2005-04-16 15:20:36 -07001077 /* Create a page with the proper size buffers.. */
Gioh Kim3b5e6452014-09-04 22:04:42 -04001078 return grow_dev_page(bdev, block, index, size, sizebits, gfp);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001079}
1080
Eric Biggers0026ba42016-09-12 13:30:41 -07001081static struct buffer_head *
Gioh Kim3b5e6452014-09-04 22:04:42 -04001082__getblk_slow(struct block_device *bdev, sector_t block,
1083 unsigned size, gfp_t gfp)
Linus Torvalds1da177e2005-04-16 15:20:36 -07001084{
1085 /* Size must be multiple of hard sectorsize */
Martin K. Petersene1defc42009-05-22 17:17:49 -04001086 if (unlikely(size & (bdev_logical_block_size(bdev)-1) ||
Linus Torvalds1da177e2005-04-16 15:20:36 -07001087 (size < 512 || size > PAGE_SIZE))) {
1088 printk(KERN_ERR "getblk(): invalid block size %d requested\n",
1089 size);
Martin K. Petersene1defc42009-05-22 17:17:49 -04001090 printk(KERN_ERR "logical block size: %d\n",
1091 bdev_logical_block_size(bdev));
Linus Torvalds1da177e2005-04-16 15:20:36 -07001092
1093 dump_stack();
1094 return NULL;
1095 }
1096
Hugh Dickins676ce6d2012-08-23 12:17:36 +02001097 for (;;) {
1098 struct buffer_head *bh;
1099 int ret;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001100
1101 bh = __find_get_block(bdev, block, size);
1102 if (bh)
1103 return bh;
Hugh Dickins676ce6d2012-08-23 12:17:36 +02001104
Gioh Kim3b5e6452014-09-04 22:04:42 -04001105 ret = grow_buffers(bdev, block, size, gfp);
Hugh Dickins676ce6d2012-08-23 12:17:36 +02001106 if (ret < 0)
1107 return NULL;
1108 if (ret == 0)
1109 free_more_memory();
Linus Torvalds1da177e2005-04-16 15:20:36 -07001110 }
1111}
1112
1113/*
1114 * The relationship between dirty buffers and dirty pages:
1115 *
1116 * Whenever a page has any dirty buffers, the page's dirty bit is set, and
1117 * the page is tagged dirty in its radix tree.
1118 *
1119 * At all times, the dirtiness of the buffers represents the dirtiness of
1120 * subsections of the page. If the page has buffers, the page dirty bit is
1121 * merely a hint about the true dirty state.
1122 *
1123 * When a page is set dirty in its entirety, all its buffers are marked dirty
1124 * (if the page has buffers).
1125 *
1126 * When a buffer is marked dirty, its page is dirtied, but the page's other
1127 * buffers are not.
1128 *
1129 * Also. When blockdev buffers are explicitly read with bread(), they
1130 * individually become uptodate. But their backing page remains not
1131 * uptodate - even if all of its buffers are uptodate. A subsequent
1132 * block_read_full_page() against that page will discover all the uptodate
1133 * buffers, will set the page uptodate and will perform no I/O.
1134 */
1135
1136/**
1137 * mark_buffer_dirty - mark a buffer_head as needing writeout
Martin Waitz67be2dd2005-05-01 08:59:26 -07001138 * @bh: the buffer_head to mark dirty
Linus Torvalds1da177e2005-04-16 15:20:36 -07001139 *
1140 * mark_buffer_dirty() will set the dirty bit against the buffer, then set its
1141 * backing page dirty, then tag the page as dirty in its address_space's radix
1142 * tree and then attach the address_space's inode to its superblock's dirty
1143 * inode list.
1144 *
1145 * mark_buffer_dirty() is atomic. It takes bh->b_page->mapping->private_lock,
Dave Chinner250df6e2011-03-22 22:23:36 +11001146 * mapping->tree_lock and mapping->host->i_lock.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001147 */
Harvey Harrisonfc9b52c2008-02-08 04:19:52 -08001148void mark_buffer_dirty(struct buffer_head *bh)
Linus Torvalds1da177e2005-04-16 15:20:36 -07001149{
Nick Piggin787d2212007-07-17 04:03:34 -07001150 WARN_ON_ONCE(!buffer_uptodate(bh));
Linus Torvalds1be62dc2008-04-04 14:38:17 -07001151
Tejun Heo5305cb82013-01-11 13:06:36 -08001152 trace_block_dirty_buffer(bh);
1153
Linus Torvalds1be62dc2008-04-04 14:38:17 -07001154 /*
1155 * Very *carefully* optimize the it-is-already-dirty case.
1156 *
1157 * Don't let the final "is it dirty" escape to before we
1158 * perhaps modified the buffer.
1159 */
1160 if (buffer_dirty(bh)) {
1161 smp_mb();
1162 if (buffer_dirty(bh))
1163 return;
1164 }
1165
Linus Torvaldsa8e7d492009-03-19 11:32:05 -07001166 if (!test_set_buffer_dirty(bh)) {
1167 struct page *page = bh->b_page;
Greg Thelenc4843a72015-05-22 17:13:16 -04001168 struct address_space *mapping = NULL;
Greg Thelenc4843a72015-05-22 17:13:16 -04001169
Johannes Weiner62cccb82016-03-15 14:57:22 -07001170 lock_page_memcg(page);
Linus Torvalds8e9d78e2009-08-21 17:40:08 -07001171 if (!TestSetPageDirty(page)) {
Greg Thelenc4843a72015-05-22 17:13:16 -04001172 mapping = page_mapping(page);
Linus Torvalds8e9d78e2009-08-21 17:40:08 -07001173 if (mapping)
Johannes Weiner62cccb82016-03-15 14:57:22 -07001174 __set_page_dirty(page, mapping, 0);
Linus Torvalds8e9d78e2009-08-21 17:40:08 -07001175 }
Johannes Weiner62cccb82016-03-15 14:57:22 -07001176 unlock_page_memcg(page);
Greg Thelenc4843a72015-05-22 17:13:16 -04001177 if (mapping)
1178 __mark_inode_dirty(mapping->host, I_DIRTY_PAGES);
Linus Torvaldsa8e7d492009-03-19 11:32:05 -07001179 }
Linus Torvalds1da177e2005-04-16 15:20:36 -07001180}
H Hartley Sweeten1fe72ea2009-09-22 16:43:51 -07001181EXPORT_SYMBOL(mark_buffer_dirty);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001182
1183/*
1184 * Decrement a buffer_head's reference count. If all buffers against a page
1185 * have zero reference count, are clean and unlocked, and if the page is clean
1186 * and unlocked then try_to_free_buffers() may strip the buffers from the page
1187 * in preparation for freeing it (sometimes, rarely, buffers are removed from
1188 * a page but it ends up not being freed, and buffers may later be reattached).
1189 */
1190void __brelse(struct buffer_head * buf)
1191{
1192 if (atomic_read(&buf->b_count)) {
1193 put_bh(buf);
1194 return;
1195 }
Arjan van de Ven5c752ad2008-07-25 19:45:40 -07001196 WARN(1, KERN_ERR "VFS: brelse: Trying to free free buffer\n");
Linus Torvalds1da177e2005-04-16 15:20:36 -07001197}
H Hartley Sweeten1fe72ea2009-09-22 16:43:51 -07001198EXPORT_SYMBOL(__brelse);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001199
1200/*
1201 * bforget() is like brelse(), except it discards any
1202 * potentially dirty data.
1203 */
1204void __bforget(struct buffer_head *bh)
1205{
1206 clear_buffer_dirty(bh);
Jan Kara535ee2f2008-02-08 04:21:59 -08001207 if (bh->b_assoc_map) {
Linus Torvalds1da177e2005-04-16 15:20:36 -07001208 struct address_space *buffer_mapping = bh->b_page->mapping;
1209
1210 spin_lock(&buffer_mapping->private_lock);
1211 list_del_init(&bh->b_assoc_buffers);
Jan Kara58ff4072006-10-17 00:10:19 -07001212 bh->b_assoc_map = NULL;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001213 spin_unlock(&buffer_mapping->private_lock);
1214 }
1215 __brelse(bh);
1216}
H Hartley Sweeten1fe72ea2009-09-22 16:43:51 -07001217EXPORT_SYMBOL(__bforget);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001218
1219static struct buffer_head *__bread_slow(struct buffer_head *bh)
1220{
1221 lock_buffer(bh);
1222 if (buffer_uptodate(bh)) {
1223 unlock_buffer(bh);
1224 return bh;
1225 } else {
1226 get_bh(bh);
1227 bh->b_end_io = end_buffer_read_sync;
Mike Christie2a222ca2016-06-05 14:31:43 -05001228 submit_bh(REQ_OP_READ, 0, bh);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001229 wait_on_buffer(bh);
1230 if (buffer_uptodate(bh))
1231 return bh;
1232 }
1233 brelse(bh);
1234 return NULL;
1235}
1236
1237/*
1238 * Per-cpu buffer LRU implementation. To reduce the cost of __find_get_block().
1239 * The bhs[] array is sorted - newest buffer is at bhs[0]. Buffers have their
1240 * refcount elevated by one when they're in an LRU. A buffer can only appear
1241 * once in a particular CPU's LRU. A single buffer can be present in multiple
1242 * CPU's LRUs at the same time.
1243 *
1244 * This is a transparent caching front-end to sb_bread(), sb_getblk() and
1245 * sb_find_get_block().
1246 *
1247 * The LRUs themselves only need locking against invalidate_bh_lrus. We use
1248 * a local interrupt disable for that.
1249 */
1250
Sebastien Buisson86cf78d2014-10-09 15:29:38 -07001251#define BH_LRU_SIZE 16
Linus Torvalds1da177e2005-04-16 15:20:36 -07001252
1253struct bh_lru {
1254 struct buffer_head *bhs[BH_LRU_SIZE];
1255};
1256
1257static DEFINE_PER_CPU(struct bh_lru, bh_lrus) = {{ NULL }};
1258
1259#ifdef CONFIG_SMP
1260#define bh_lru_lock() local_irq_disable()
1261#define bh_lru_unlock() local_irq_enable()
1262#else
1263#define bh_lru_lock() preempt_disable()
1264#define bh_lru_unlock() preempt_enable()
1265#endif
1266
1267static inline void check_irqs_on(void)
1268{
1269#ifdef irqs_disabled
1270 BUG_ON(irqs_disabled());
1271#endif
1272}
1273
1274/*
1275 * The LRU management algorithm is dopey-but-simple. Sorry.
1276 */
1277static void bh_lru_install(struct buffer_head *bh)
1278{
1279 struct buffer_head *evictee = NULL;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001280
1281 check_irqs_on();
1282 bh_lru_lock();
Christoph Lameterc7b92512010-12-06 11:16:28 -06001283 if (__this_cpu_read(bh_lrus.bhs[0]) != bh) {
Linus Torvalds1da177e2005-04-16 15:20:36 -07001284 struct buffer_head *bhs[BH_LRU_SIZE];
1285 int in;
1286 int out = 0;
1287
1288 get_bh(bh);
1289 bhs[out++] = bh;
1290 for (in = 0; in < BH_LRU_SIZE; in++) {
Christoph Lameterc7b92512010-12-06 11:16:28 -06001291 struct buffer_head *bh2 =
1292 __this_cpu_read(bh_lrus.bhs[in]);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001293
1294 if (bh2 == bh) {
1295 __brelse(bh2);
1296 } else {
1297 if (out >= BH_LRU_SIZE) {
1298 BUG_ON(evictee != NULL);
1299 evictee = bh2;
1300 } else {
1301 bhs[out++] = bh2;
1302 }
1303 }
1304 }
1305 while (out < BH_LRU_SIZE)
1306 bhs[out++] = NULL;
Christoph Lameterca6673b02013-12-03 17:32:53 -06001307 memcpy(this_cpu_ptr(&bh_lrus.bhs), bhs, sizeof(bhs));
Linus Torvalds1da177e2005-04-16 15:20:36 -07001308 }
1309 bh_lru_unlock();
1310
1311 if (evictee)
1312 __brelse(evictee);
1313}
1314
1315/*
1316 * Look up the bh in this cpu's LRU. If it's there, move it to the head.
1317 */
Arjan van de Ven858119e2006-01-14 13:20:43 -08001318static struct buffer_head *
Tomasz Kvarsin3991d3b2007-02-12 00:52:14 -08001319lookup_bh_lru(struct block_device *bdev, sector_t block, unsigned size)
Linus Torvalds1da177e2005-04-16 15:20:36 -07001320{
1321 struct buffer_head *ret = NULL;
Tomasz Kvarsin3991d3b2007-02-12 00:52:14 -08001322 unsigned int i;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001323
1324 check_irqs_on();
1325 bh_lru_lock();
Linus Torvalds1da177e2005-04-16 15:20:36 -07001326 for (i = 0; i < BH_LRU_SIZE; i++) {
Christoph Lameterc7b92512010-12-06 11:16:28 -06001327 struct buffer_head *bh = __this_cpu_read(bh_lrus.bhs[i]);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001328
Zach Brown9470dd52014-10-13 15:55:05 -07001329 if (bh && bh->b_blocknr == block && bh->b_bdev == bdev &&
1330 bh->b_size == size) {
Linus Torvalds1da177e2005-04-16 15:20:36 -07001331 if (i) {
1332 while (i) {
Christoph Lameterc7b92512010-12-06 11:16:28 -06001333 __this_cpu_write(bh_lrus.bhs[i],
1334 __this_cpu_read(bh_lrus.bhs[i - 1]));
Linus Torvalds1da177e2005-04-16 15:20:36 -07001335 i--;
1336 }
Christoph Lameterc7b92512010-12-06 11:16:28 -06001337 __this_cpu_write(bh_lrus.bhs[0], bh);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001338 }
1339 get_bh(bh);
1340 ret = bh;
1341 break;
1342 }
1343 }
1344 bh_lru_unlock();
1345 return ret;
1346}
1347
1348/*
1349 * Perform a pagecache lookup for the matching buffer. If it's there, refresh
1350 * it in the LRU and mark it as accessed. If it is not present then return
1351 * NULL
1352 */
1353struct buffer_head *
Tomasz Kvarsin3991d3b2007-02-12 00:52:14 -08001354__find_get_block(struct block_device *bdev, sector_t block, unsigned size)
Linus Torvalds1da177e2005-04-16 15:20:36 -07001355{
1356 struct buffer_head *bh = lookup_bh_lru(bdev, block, size);
1357
1358 if (bh == NULL) {
Mel Gorman2457aec2014-06-04 16:10:31 -07001359 /* __find_get_block_slow will mark the page accessed */
Coywolf Qi Hunt385fd4c2005-11-07 00:59:39 -08001360 bh = __find_get_block_slow(bdev, block);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001361 if (bh)
1362 bh_lru_install(bh);
Mel Gorman2457aec2014-06-04 16:10:31 -07001363 } else
Linus Torvalds1da177e2005-04-16 15:20:36 -07001364 touch_buffer(bh);
Mel Gorman2457aec2014-06-04 16:10:31 -07001365
Linus Torvalds1da177e2005-04-16 15:20:36 -07001366 return bh;
1367}
1368EXPORT_SYMBOL(__find_get_block);
1369
1370/*
Gioh Kim3b5e6452014-09-04 22:04:42 -04001371 * __getblk_gfp() will locate (and, if necessary, create) the buffer_head
Linus Torvalds1da177e2005-04-16 15:20:36 -07001372 * which corresponds to the passed block_device, block and size. The
1373 * returned buffer has its reference count incremented.
1374 *
Gioh Kim3b5e6452014-09-04 22:04:42 -04001375 * __getblk_gfp() will lock up the machine if grow_dev_page's
1376 * try_to_free_buffers() attempt is failing. FIXME, perhaps?
Linus Torvalds1da177e2005-04-16 15:20:36 -07001377 */
1378struct buffer_head *
Gioh Kim3b5e6452014-09-04 22:04:42 -04001379__getblk_gfp(struct block_device *bdev, sector_t block,
1380 unsigned size, gfp_t gfp)
Linus Torvalds1da177e2005-04-16 15:20:36 -07001381{
1382 struct buffer_head *bh = __find_get_block(bdev, block, size);
1383
1384 might_sleep();
1385 if (bh == NULL)
Gioh Kim3b5e6452014-09-04 22:04:42 -04001386 bh = __getblk_slow(bdev, block, size, gfp);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001387 return bh;
1388}
Gioh Kim3b5e6452014-09-04 22:04:42 -04001389EXPORT_SYMBOL(__getblk_gfp);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001390
1391/*
1392 * Do async read-ahead on a buffer..
1393 */
Tomasz Kvarsin3991d3b2007-02-12 00:52:14 -08001394void __breadahead(struct block_device *bdev, sector_t block, unsigned size)
Linus Torvalds1da177e2005-04-16 15:20:36 -07001395{
1396 struct buffer_head *bh = __getblk(bdev, block, size);
Andrew Mortona3e713b2005-10-30 15:03:15 -08001397 if (likely(bh)) {
Christoph Hellwig70246282016-07-19 11:28:41 +02001398 ll_rw_block(REQ_OP_READ, REQ_RAHEAD, 1, &bh);
Andrew Mortona3e713b2005-10-30 15:03:15 -08001399 brelse(bh);
1400 }
Linus Torvalds1da177e2005-04-16 15:20:36 -07001401}
1402EXPORT_SYMBOL(__breadahead);
1403
1404/**
Gioh Kim3b5e6452014-09-04 22:04:42 -04001405 * __bread_gfp() - reads a specified block and returns the bh
Martin Waitz67be2dd2005-05-01 08:59:26 -07001406 * @bdev: the block_device to read from
Linus Torvalds1da177e2005-04-16 15:20:36 -07001407 * @block: number of block
1408 * @size: size (in bytes) to read
Gioh Kim3b5e6452014-09-04 22:04:42 -04001409 * @gfp: page allocation flag
1410 *
Linus Torvalds1da177e2005-04-16 15:20:36 -07001411 * Reads a specified block, and returns buffer head that contains it.
Gioh Kim3b5e6452014-09-04 22:04:42 -04001412 * The page cache can be allocated from non-movable area
1413 * not to prevent page migration if you set gfp to zero.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001414 * It returns NULL if the block was unreadable.
1415 */
1416struct buffer_head *
Gioh Kim3b5e6452014-09-04 22:04:42 -04001417__bread_gfp(struct block_device *bdev, sector_t block,
1418 unsigned size, gfp_t gfp)
Linus Torvalds1da177e2005-04-16 15:20:36 -07001419{
Gioh Kim3b5e6452014-09-04 22:04:42 -04001420 struct buffer_head *bh = __getblk_gfp(bdev, block, size, gfp);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001421
Andrew Mortona3e713b2005-10-30 15:03:15 -08001422 if (likely(bh) && !buffer_uptodate(bh))
Linus Torvalds1da177e2005-04-16 15:20:36 -07001423 bh = __bread_slow(bh);
1424 return bh;
1425}
Gioh Kim3b5e6452014-09-04 22:04:42 -04001426EXPORT_SYMBOL(__bread_gfp);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001427
1428/*
1429 * invalidate_bh_lrus() is called rarely - but not only at unmount.
1430 * This doesn't race because it runs in each cpu either in irq
1431 * or with preempt disabled.
1432 */
1433static void invalidate_bh_lru(void *arg)
1434{
1435 struct bh_lru *b = &get_cpu_var(bh_lrus);
1436 int i;
1437
1438 for (i = 0; i < BH_LRU_SIZE; i++) {
1439 brelse(b->bhs[i]);
1440 b->bhs[i] = NULL;
1441 }
1442 put_cpu_var(bh_lrus);
1443}
Gilad Ben-Yossef42be35d2012-03-28 14:42:45 -07001444
1445static bool has_bh_in_lru(int cpu, void *dummy)
1446{
1447 struct bh_lru *b = per_cpu_ptr(&bh_lrus, cpu);
1448 int i;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001449
Gilad Ben-Yossef42be35d2012-03-28 14:42:45 -07001450 for (i = 0; i < BH_LRU_SIZE; i++) {
1451 if (b->bhs[i])
1452 return 1;
1453 }
1454
1455 return 0;
1456}
1457
Peter Zijlstraf9a14392007-05-06 14:49:55 -07001458void invalidate_bh_lrus(void)
Linus Torvalds1da177e2005-04-16 15:20:36 -07001459{
Gilad Ben-Yossef42be35d2012-03-28 14:42:45 -07001460 on_each_cpu_cond(has_bh_in_lru, invalidate_bh_lru, NULL, 1, GFP_KERNEL);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001461}
Nick Piggin9db55792008-02-08 04:19:49 -08001462EXPORT_SYMBOL_GPL(invalidate_bh_lrus);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001463
1464void set_bh_page(struct buffer_head *bh,
1465 struct page *page, unsigned long offset)
1466{
1467 bh->b_page = page;
Eric Sesterhenne827f922006-03-26 18:24:46 +02001468 BUG_ON(offset >= PAGE_SIZE);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001469 if (PageHighMem(page))
1470 /*
1471 * This catches illegal uses and preserves the offset:
1472 */
1473 bh->b_data = (char *)(0 + offset);
1474 else
1475 bh->b_data = page_address(page) + offset;
1476}
1477EXPORT_SYMBOL(set_bh_page);
1478
1479/*
1480 * Called when truncating a buffer on a page completely.
1481 */
Mel Gormane7470ee2014-06-04 16:10:29 -07001482
1483/* Bits that are cleared during an invalidate */
1484#define BUFFER_FLAGS_DISCARD \
1485 (1 << BH_Mapped | 1 << BH_New | 1 << BH_Req | \
1486 1 << BH_Delay | 1 << BH_Unwritten)
1487
Arjan van de Ven858119e2006-01-14 13:20:43 -08001488static void discard_buffer(struct buffer_head * bh)
Linus Torvalds1da177e2005-04-16 15:20:36 -07001489{
Mel Gormane7470ee2014-06-04 16:10:29 -07001490 unsigned long b_state, b_state_old;
1491
Linus Torvalds1da177e2005-04-16 15:20:36 -07001492 lock_buffer(bh);
1493 clear_buffer_dirty(bh);
1494 bh->b_bdev = NULL;
Mel Gormane7470ee2014-06-04 16:10:29 -07001495 b_state = bh->b_state;
1496 for (;;) {
1497 b_state_old = cmpxchg(&bh->b_state, b_state,
1498 (b_state & ~BUFFER_FLAGS_DISCARD));
1499 if (b_state_old == b_state)
1500 break;
1501 b_state = b_state_old;
1502 }
Linus Torvalds1da177e2005-04-16 15:20:36 -07001503 unlock_buffer(bh);
1504}
1505
1506/**
Wang Sheng-Hui814e1d22011-09-01 08:22:57 +08001507 * block_invalidatepage - invalidate part or all of a buffer-backed page
Linus Torvalds1da177e2005-04-16 15:20:36 -07001508 *
1509 * @page: the page which is affected
Lukas Czernerd47992f2013-05-21 23:17:23 -04001510 * @offset: start of the range to invalidate
1511 * @length: length of the range to invalidate
Linus Torvalds1da177e2005-04-16 15:20:36 -07001512 *
1513 * block_invalidatepage() is called when all or part of the page has become
Wang Sheng-Hui814e1d22011-09-01 08:22:57 +08001514 * invalidated by a truncate operation.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001515 *
1516 * block_invalidatepage() does not have to release all buffers, but it must
1517 * ensure that no dirty buffer is left outside @offset and that no I/O
1518 * is underway against any of the blocks which are outside the truncation
1519 * point. Because the caller is about to free (and possibly reuse) those
1520 * blocks on-disk.
1521 */
Lukas Czernerd47992f2013-05-21 23:17:23 -04001522void block_invalidatepage(struct page *page, unsigned int offset,
1523 unsigned int length)
Linus Torvalds1da177e2005-04-16 15:20:36 -07001524{
1525 struct buffer_head *head, *bh, *next;
1526 unsigned int curr_off = 0;
Lukas Czernerd47992f2013-05-21 23:17:23 -04001527 unsigned int stop = length + offset;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001528
1529 BUG_ON(!PageLocked(page));
1530 if (!page_has_buffers(page))
1531 goto out;
1532
Lukas Czernerd47992f2013-05-21 23:17:23 -04001533 /*
1534 * Check for overflow
1535 */
Kirill A. Shutemov09cbfea2016-04-01 15:29:47 +03001536 BUG_ON(stop > PAGE_SIZE || stop < length);
Lukas Czernerd47992f2013-05-21 23:17:23 -04001537
Linus Torvalds1da177e2005-04-16 15:20:36 -07001538 head = page_buffers(page);
1539 bh = head;
1540 do {
1541 unsigned int next_off = curr_off + bh->b_size;
1542 next = bh->b_this_page;
1543
1544 /*
Lukas Czernerd47992f2013-05-21 23:17:23 -04001545 * Are we still fully in range ?
1546 */
1547 if (next_off > stop)
1548 goto out;
1549
1550 /*
Linus Torvalds1da177e2005-04-16 15:20:36 -07001551 * is this block fully invalidated?
1552 */
1553 if (offset <= curr_off)
1554 discard_buffer(bh);
1555 curr_off = next_off;
1556 bh = next;
1557 } while (bh != head);
1558
1559 /*
1560 * We release buffers only if the entire page is being invalidated.
1561 * The get_block cached value has been unconditionally invalidated,
1562 * so real IO is not possible anymore.
1563 */
1564 if (offset == 0)
NeilBrown2ff28e22006-03-26 01:37:18 -08001565 try_to_release_page(page, 0);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001566out:
NeilBrown2ff28e22006-03-26 01:37:18 -08001567 return;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001568}
1569EXPORT_SYMBOL(block_invalidatepage);
1570
Lukas Czernerd47992f2013-05-21 23:17:23 -04001571
Linus Torvalds1da177e2005-04-16 15:20:36 -07001572/*
1573 * We attach and possibly dirty the buffers atomically wrt
1574 * __set_page_dirty_buffers() via private_lock. try_to_free_buffers
1575 * is already excluded via the page lock.
1576 */
1577void create_empty_buffers(struct page *page,
1578 unsigned long blocksize, unsigned long b_state)
1579{
1580 struct buffer_head *bh, *head, *tail;
1581
1582 head = alloc_page_buffers(page, blocksize, 1);
1583 bh = head;
1584 do {
1585 bh->b_state |= b_state;
1586 tail = bh;
1587 bh = bh->b_this_page;
1588 } while (bh);
1589 tail->b_this_page = head;
1590
1591 spin_lock(&page->mapping->private_lock);
1592 if (PageUptodate(page) || PageDirty(page)) {
1593 bh = head;
1594 do {
1595 if (PageDirty(page))
1596 set_buffer_dirty(bh);
1597 if (PageUptodate(page))
1598 set_buffer_uptodate(bh);
1599 bh = bh->b_this_page;
1600 } while (bh != head);
1601 }
1602 attach_page_buffers(page, head);
1603 spin_unlock(&page->mapping->private_lock);
1604}
1605EXPORT_SYMBOL(create_empty_buffers);
1606
1607/*
1608 * We are taking a block for data and we don't want any output from any
1609 * buffer-cache aliases starting from return from that function and
1610 * until the moment when something will explicitly mark the buffer
1611 * dirty (hopefully that will not happen until we will free that block ;-)
1612 * We don't even need to mark it not-uptodate - nobody can expect
1613 * anything from a newly allocated buffer anyway. We used to used
1614 * unmap_buffer() for such invalidation, but that was wrong. We definitely
1615 * don't want to mark the alias unmapped, for example - it would confuse
1616 * anyone who might pick it with bread() afterwards...
1617 *
1618 * Also.. Note that bforget() doesn't lock the buffer. So there can
1619 * be writeout I/O going on against recently-freed buffers. We don't
1620 * wait on that I/O in bforget() - it's more efficient to wait on the I/O
1621 * only if we really need to. That happens here.
1622 */
1623void unmap_underlying_metadata(struct block_device *bdev, sector_t block)
1624{
1625 struct buffer_head *old_bh;
1626
1627 might_sleep();
1628
Coywolf Qi Hunt385fd4c2005-11-07 00:59:39 -08001629 old_bh = __find_get_block_slow(bdev, block);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001630 if (old_bh) {
1631 clear_buffer_dirty(old_bh);
1632 wait_on_buffer(old_bh);
1633 clear_buffer_req(old_bh);
1634 __brelse(old_bh);
1635 }
1636}
1637EXPORT_SYMBOL(unmap_underlying_metadata);
1638
1639/*
Linus Torvalds45bce8f2012-11-29 10:21:43 -08001640 * Size is a power-of-two in the range 512..PAGE_SIZE,
1641 * and the case we care about most is PAGE_SIZE.
1642 *
1643 * So this *could* possibly be written with those
1644 * constraints in mind (relevant mostly if some
1645 * architecture has a slow bit-scan instruction)
1646 */
1647static inline int block_size_bits(unsigned int blocksize)
1648{
1649 return ilog2(blocksize);
1650}
1651
1652static struct buffer_head *create_page_buffers(struct page *page, struct inode *inode, unsigned int b_state)
1653{
1654 BUG_ON(!PageLocked(page));
1655
1656 if (!page_has_buffers(page))
1657 create_empty_buffers(page, 1 << ACCESS_ONCE(inode->i_blkbits), b_state);
1658 return page_buffers(page);
1659}
1660
1661/*
Linus Torvalds1da177e2005-04-16 15:20:36 -07001662 * NOTE! All mapped/uptodate combinations are valid:
1663 *
1664 * Mapped Uptodate Meaning
1665 *
1666 * No No "unknown" - must do get_block()
1667 * No Yes "hole" - zero-filled
1668 * Yes No "allocated" - allocated on disk, not read in
1669 * Yes Yes "valid" - allocated and up-to-date in memory.
1670 *
1671 * "Dirty" is valid only with the last case (mapped+uptodate).
1672 */
1673
1674/*
1675 * While block_write_full_page is writing back the dirty buffers under
1676 * the page lock, whoever dirtied the buffers may decide to clean them
1677 * again at any time. We handle that by only looking at the buffer
1678 * state inside lock_buffer().
1679 *
1680 * If block_write_full_page() is called for regular writeback
1681 * (wbc->sync_mode == WB_SYNC_NONE) then it will redirty a page which has a
1682 * locked buffer. This only can happen if someone has written the buffer
1683 * directly, with submit_bh(). At the address_space level PageWriteback
1684 * prevents this contention from occurring.
Theodore Ts'o6e34eed2009-04-07 18:12:43 -04001685 *
1686 * If block_write_full_page() is called with wbc->sync_mode ==
Jens Axboe721a9602011-03-09 11:56:30 +01001687 * WB_SYNC_ALL, the writes are posted using WRITE_SYNC; this
1688 * causes the writes to be flagged as synchronous writes.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001689 */
Benjamin Marzinskib4bba382016-06-27 09:58:40 -05001690int __block_write_full_page(struct inode *inode, struct page *page,
Chris Mason35c80d52009-04-15 13:22:38 -04001691 get_block_t *get_block, struct writeback_control *wbc,
1692 bh_end_io_t *handler)
Linus Torvalds1da177e2005-04-16 15:20:36 -07001693{
1694 int err;
1695 sector_t block;
1696 sector_t last_block;
Andrew Mortonf0fbd5f2005-05-05 16:15:48 -07001697 struct buffer_head *bh, *head;
Linus Torvalds45bce8f2012-11-29 10:21:43 -08001698 unsigned int blocksize, bbits;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001699 int nr_underway = 0;
Mike Christie2a222ca2016-06-05 14:31:43 -05001700 int write_flags = (wbc->sync_mode == WB_SYNC_ALL ? WRITE_SYNC : 0);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001701
Linus Torvalds45bce8f2012-11-29 10:21:43 -08001702 head = create_page_buffers(page, inode,
Linus Torvalds1da177e2005-04-16 15:20:36 -07001703 (1 << BH_Dirty)|(1 << BH_Uptodate));
Linus Torvalds1da177e2005-04-16 15:20:36 -07001704
1705 /*
1706 * Be very careful. We have no exclusion from __set_page_dirty_buffers
1707 * here, and the (potentially unmapped) buffers may become dirty at
1708 * any time. If a buffer becomes dirty here after we've inspected it
1709 * then we just miss that fact, and the page stays dirty.
1710 *
1711 * Buffers outside i_size may be dirtied by __set_page_dirty_buffers;
1712 * handle that here by just cleaning them.
1713 */
1714
Linus Torvalds1da177e2005-04-16 15:20:36 -07001715 bh = head;
Linus Torvalds45bce8f2012-11-29 10:21:43 -08001716 blocksize = bh->b_size;
1717 bbits = block_size_bits(blocksize);
1718
Kirill A. Shutemov09cbfea2016-04-01 15:29:47 +03001719 block = (sector_t)page->index << (PAGE_SHIFT - bbits);
Linus Torvalds45bce8f2012-11-29 10:21:43 -08001720 last_block = (i_size_read(inode) - 1) >> bbits;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001721
1722 /*
1723 * Get all the dirty buffers mapped to disk addresses and
1724 * handle any aliases from the underlying blockdev's mapping.
1725 */
1726 do {
1727 if (block > last_block) {
1728 /*
1729 * mapped buffers outside i_size will occur, because
1730 * this page can be outside i_size when there is a
1731 * truncate in progress.
1732 */
1733 /*
1734 * The buffer was zeroed by block_write_full_page()
1735 */
1736 clear_buffer_dirty(bh);
1737 set_buffer_uptodate(bh);
Alex Tomas29a814d2008-07-11 19:27:31 -04001738 } else if ((!buffer_mapped(bh) || buffer_delay(bh)) &&
1739 buffer_dirty(bh)) {
Badari Pulavartyb0cf2322006-03-26 01:38:00 -08001740 WARN_ON(bh->b_size != blocksize);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001741 err = get_block(inode, block, bh, 1);
1742 if (err)
1743 goto recover;
Alex Tomas29a814d2008-07-11 19:27:31 -04001744 clear_buffer_delay(bh);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001745 if (buffer_new(bh)) {
1746 /* blockdev mappings never come here */
1747 clear_buffer_new(bh);
1748 unmap_underlying_metadata(bh->b_bdev,
1749 bh->b_blocknr);
1750 }
1751 }
1752 bh = bh->b_this_page;
1753 block++;
1754 } while (bh != head);
1755
1756 do {
Linus Torvalds1da177e2005-04-16 15:20:36 -07001757 if (!buffer_mapped(bh))
1758 continue;
1759 /*
1760 * If it's a fully non-blocking write attempt and we cannot
1761 * lock the buffer then redirty the page. Note that this can
Jens Axboe5b0830c2009-09-23 19:37:09 +02001762 * potentially cause a busy-wait loop from writeback threads
1763 * and kswapd activity, but those code paths have their own
1764 * higher-level throttling.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001765 */
Wu Fengguang1b430be2010-10-26 14:21:26 -07001766 if (wbc->sync_mode != WB_SYNC_NONE) {
Linus Torvalds1da177e2005-04-16 15:20:36 -07001767 lock_buffer(bh);
Nick Pigginca5de402008-08-02 12:02:13 +02001768 } else if (!trylock_buffer(bh)) {
Linus Torvalds1da177e2005-04-16 15:20:36 -07001769 redirty_page_for_writepage(wbc, page);
1770 continue;
1771 }
1772 if (test_clear_buffer_dirty(bh)) {
Chris Mason35c80d52009-04-15 13:22:38 -04001773 mark_buffer_async_write_endio(bh, handler);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001774 } else {
1775 unlock_buffer(bh);
1776 }
1777 } while ((bh = bh->b_this_page) != head);
1778
1779 /*
1780 * The page and its buffers are protected by PageWriteback(), so we can
1781 * drop the bh refcounts early.
1782 */
1783 BUG_ON(PageWriteback(page));
1784 set_page_writeback(page);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001785
1786 do {
1787 struct buffer_head *next = bh->b_this_page;
1788 if (buffer_async_write(bh)) {
Mike Christie2a222ca2016-06-05 14:31:43 -05001789 submit_bh_wbc(REQ_OP_WRITE, write_flags, bh, 0, wbc);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001790 nr_underway++;
1791 }
Linus Torvalds1da177e2005-04-16 15:20:36 -07001792 bh = next;
1793 } while (bh != head);
Andrew Morton05937ba2005-05-05 16:15:47 -07001794 unlock_page(page);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001795
1796 err = 0;
1797done:
1798 if (nr_underway == 0) {
1799 /*
1800 * The page was marked dirty, but the buffers were
1801 * clean. Someone wrote them back by hand with
1802 * ll_rw_block/submit_bh. A rare case.
1803 */
Linus Torvalds1da177e2005-04-16 15:20:36 -07001804 end_page_writeback(page);
Nick Piggin3d67f2d2007-05-06 14:49:05 -07001805
Linus Torvalds1da177e2005-04-16 15:20:36 -07001806 /*
1807 * The page and buffer_heads can be released at any time from
1808 * here on.
1809 */
Linus Torvalds1da177e2005-04-16 15:20:36 -07001810 }
1811 return err;
1812
1813recover:
1814 /*
1815 * ENOSPC, or some other error. We may already have added some
1816 * blocks to the file, so we need to write these out to avoid
1817 * exposing stale data.
1818 * The page is currently locked and not marked for writeback
1819 */
1820 bh = head;
1821 /* Recovery: lock and submit the mapped buffers */
1822 do {
Alex Tomas29a814d2008-07-11 19:27:31 -04001823 if (buffer_mapped(bh) && buffer_dirty(bh) &&
1824 !buffer_delay(bh)) {
Linus Torvalds1da177e2005-04-16 15:20:36 -07001825 lock_buffer(bh);
Chris Mason35c80d52009-04-15 13:22:38 -04001826 mark_buffer_async_write_endio(bh, handler);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001827 } else {
1828 /*
1829 * The buffer may have been set dirty during
1830 * attachment to a dirty page.
1831 */
1832 clear_buffer_dirty(bh);
1833 }
1834 } while ((bh = bh->b_this_page) != head);
1835 SetPageError(page);
1836 BUG_ON(PageWriteback(page));
Andrew Morton7e4c3692007-05-08 00:23:27 -07001837 mapping_set_error(page->mapping, err);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001838 set_page_writeback(page);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001839 do {
1840 struct buffer_head *next = bh->b_this_page;
1841 if (buffer_async_write(bh)) {
1842 clear_buffer_dirty(bh);
Mike Christie2a222ca2016-06-05 14:31:43 -05001843 submit_bh_wbc(REQ_OP_WRITE, write_flags, bh, 0, wbc);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001844 nr_underway++;
1845 }
Linus Torvalds1da177e2005-04-16 15:20:36 -07001846 bh = next;
1847 } while (bh != head);
Nick Pigginffda9d32007-02-20 13:57:54 -08001848 unlock_page(page);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001849 goto done;
1850}
Benjamin Marzinskib4bba382016-06-27 09:58:40 -05001851EXPORT_SYMBOL(__block_write_full_page);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001852
Nick Pigginafddba42007-10-16 01:25:01 -07001853/*
1854 * If a page has any new buffers, zero them out here, and mark them uptodate
1855 * and dirty so they'll be written out (in order to prevent uninitialised
1856 * block data from leaking). And clear the new bit.
1857 */
1858void page_zero_new_buffers(struct page *page, unsigned from, unsigned to)
1859{
1860 unsigned int block_start, block_end;
1861 struct buffer_head *head, *bh;
1862
1863 BUG_ON(!PageLocked(page));
1864 if (!page_has_buffers(page))
1865 return;
1866
1867 bh = head = page_buffers(page);
1868 block_start = 0;
1869 do {
1870 block_end = block_start + bh->b_size;
1871
1872 if (buffer_new(bh)) {
1873 if (block_end > from && block_start < to) {
1874 if (!PageUptodate(page)) {
1875 unsigned start, size;
1876
1877 start = max(from, block_start);
1878 size = min(to, block_end) - start;
1879
Christoph Lametereebd2aa2008-02-04 22:28:29 -08001880 zero_user(page, start, size);
Nick Pigginafddba42007-10-16 01:25:01 -07001881 set_buffer_uptodate(bh);
1882 }
1883
1884 clear_buffer_new(bh);
1885 mark_buffer_dirty(bh);
1886 }
1887 }
1888
1889 block_start = block_end;
1890 bh = bh->b_this_page;
1891 } while (bh != head);
1892}
1893EXPORT_SYMBOL(page_zero_new_buffers);
1894
Christoph Hellwigae259a92016-06-21 09:23:11 +10001895static void
1896iomap_to_bh(struct inode *inode, sector_t block, struct buffer_head *bh,
1897 struct iomap *iomap)
1898{
1899 loff_t offset = block << inode->i_blkbits;
1900
1901 bh->b_bdev = iomap->bdev;
1902
1903 /*
1904 * Block points to offset in file we need to map, iomap contains
1905 * the offset at which the map starts. If the map ends before the
1906 * current block, then do not map the buffer and let the caller
1907 * handle it.
1908 */
1909 BUG_ON(offset >= iomap->offset + iomap->length);
1910
1911 switch (iomap->type) {
1912 case IOMAP_HOLE:
1913 /*
1914 * If the buffer is not up to date or beyond the current EOF,
1915 * we need to mark it as new to ensure sub-block zeroing is
1916 * executed if necessary.
1917 */
1918 if (!buffer_uptodate(bh) ||
1919 (offset >= i_size_read(inode)))
1920 set_buffer_new(bh);
1921 break;
1922 case IOMAP_DELALLOC:
1923 if (!buffer_uptodate(bh) ||
1924 (offset >= i_size_read(inode)))
1925 set_buffer_new(bh);
1926 set_buffer_uptodate(bh);
1927 set_buffer_mapped(bh);
1928 set_buffer_delay(bh);
1929 break;
1930 case IOMAP_UNWRITTEN:
1931 /*
1932 * For unwritten regions, we always need to ensure that
1933 * sub-block writes cause the regions in the block we are not
1934 * writing to are zeroed. Set the buffer as new to ensure this.
1935 */
1936 set_buffer_new(bh);
1937 set_buffer_unwritten(bh);
1938 /* FALLTHRU */
1939 case IOMAP_MAPPED:
1940 if (offset >= i_size_read(inode))
1941 set_buffer_new(bh);
1942 bh->b_blocknr = (iomap->blkno >> (inode->i_blkbits - 9)) +
1943 ((offset - iomap->offset) >> inode->i_blkbits);
1944 set_buffer_mapped(bh);
1945 break;
1946 }
1947}
1948
1949int __block_write_begin_int(struct page *page, loff_t pos, unsigned len,
1950 get_block_t *get_block, struct iomap *iomap)
Linus Torvalds1da177e2005-04-16 15:20:36 -07001951{
Kirill A. Shutemov09cbfea2016-04-01 15:29:47 +03001952 unsigned from = pos & (PAGE_SIZE - 1);
Christoph Hellwigebdec242010-10-06 10:47:23 +02001953 unsigned to = from + len;
Christoph Hellwig6e1db882010-06-04 11:29:57 +02001954 struct inode *inode = page->mapping->host;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001955 unsigned block_start, block_end;
1956 sector_t block;
1957 int err = 0;
1958 unsigned blocksize, bbits;
1959 struct buffer_head *bh, *head, *wait[2], **wait_bh=wait;
1960
1961 BUG_ON(!PageLocked(page));
Kirill A. Shutemov09cbfea2016-04-01 15:29:47 +03001962 BUG_ON(from > PAGE_SIZE);
1963 BUG_ON(to > PAGE_SIZE);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001964 BUG_ON(from > to);
1965
Linus Torvalds45bce8f2012-11-29 10:21:43 -08001966 head = create_page_buffers(page, inode, 0);
1967 blocksize = head->b_size;
1968 bbits = block_size_bits(blocksize);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001969
Kirill A. Shutemov09cbfea2016-04-01 15:29:47 +03001970 block = (sector_t)page->index << (PAGE_SHIFT - bbits);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001971
1972 for(bh = head, block_start = 0; bh != head || !block_start;
1973 block++, block_start=block_end, bh = bh->b_this_page) {
1974 block_end = block_start + blocksize;
1975 if (block_end <= from || block_start >= to) {
1976 if (PageUptodate(page)) {
1977 if (!buffer_uptodate(bh))
1978 set_buffer_uptodate(bh);
1979 }
1980 continue;
1981 }
1982 if (buffer_new(bh))
1983 clear_buffer_new(bh);
1984 if (!buffer_mapped(bh)) {
Badari Pulavartyb0cf2322006-03-26 01:38:00 -08001985 WARN_ON(bh->b_size != blocksize);
Christoph Hellwigae259a92016-06-21 09:23:11 +10001986 if (get_block) {
1987 err = get_block(inode, block, bh, 1);
1988 if (err)
1989 break;
1990 } else {
1991 iomap_to_bh(inode, block, bh, iomap);
1992 }
1993
Linus Torvalds1da177e2005-04-16 15:20:36 -07001994 if (buffer_new(bh)) {
Linus Torvalds1da177e2005-04-16 15:20:36 -07001995 unmap_underlying_metadata(bh->b_bdev,
1996 bh->b_blocknr);
1997 if (PageUptodate(page)) {
Nick Piggin637aff42007-10-16 01:25:00 -07001998 clear_buffer_new(bh);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001999 set_buffer_uptodate(bh);
Nick Piggin637aff42007-10-16 01:25:00 -07002000 mark_buffer_dirty(bh);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002001 continue;
2002 }
Christoph Lametereebd2aa2008-02-04 22:28:29 -08002003 if (block_end > to || block_start < from)
2004 zero_user_segments(page,
2005 to, block_end,
2006 block_start, from);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002007 continue;
2008 }
2009 }
2010 if (PageUptodate(page)) {
2011 if (!buffer_uptodate(bh))
2012 set_buffer_uptodate(bh);
2013 continue;
2014 }
2015 if (!buffer_uptodate(bh) && !buffer_delay(bh) &&
David Chinner33a266d2007-02-12 00:51:41 -08002016 !buffer_unwritten(bh) &&
Linus Torvalds1da177e2005-04-16 15:20:36 -07002017 (block_start < from || block_end > to)) {
Mike Christiedfec8a12016-06-05 14:31:44 -05002018 ll_rw_block(REQ_OP_READ, 0, 1, &bh);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002019 *wait_bh++=bh;
2020 }
2021 }
2022 /*
2023 * If we issued read requests - let them complete.
2024 */
2025 while(wait_bh > wait) {
2026 wait_on_buffer(*--wait_bh);
2027 if (!buffer_uptodate(*wait_bh))
Nick Pigginf3ddbdc2005-05-05 16:15:45 -07002028 err = -EIO;
Linus Torvalds1da177e2005-04-16 15:20:36 -07002029 }
Jan Karaf9f07b62011-06-14 00:58:27 +02002030 if (unlikely(err))
Nick Pigginafddba42007-10-16 01:25:01 -07002031 page_zero_new_buffers(page, from, to);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002032 return err;
2033}
Christoph Hellwigae259a92016-06-21 09:23:11 +10002034
2035int __block_write_begin(struct page *page, loff_t pos, unsigned len,
2036 get_block_t *get_block)
2037{
2038 return __block_write_begin_int(page, pos, len, get_block, NULL);
2039}
Christoph Hellwigebdec242010-10-06 10:47:23 +02002040EXPORT_SYMBOL(__block_write_begin);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002041
2042static int __block_commit_write(struct inode *inode, struct page *page,
2043 unsigned from, unsigned to)
2044{
2045 unsigned block_start, block_end;
2046 int partial = 0;
2047 unsigned blocksize;
2048 struct buffer_head *bh, *head;
2049
Linus Torvalds45bce8f2012-11-29 10:21:43 -08002050 bh = head = page_buffers(page);
2051 blocksize = bh->b_size;
Linus Torvalds1da177e2005-04-16 15:20:36 -07002052
Linus Torvalds45bce8f2012-11-29 10:21:43 -08002053 block_start = 0;
2054 do {
Linus Torvalds1da177e2005-04-16 15:20:36 -07002055 block_end = block_start + blocksize;
2056 if (block_end <= from || block_start >= to) {
2057 if (!buffer_uptodate(bh))
2058 partial = 1;
2059 } else {
2060 set_buffer_uptodate(bh);
2061 mark_buffer_dirty(bh);
2062 }
Nick Pigginafddba42007-10-16 01:25:01 -07002063 clear_buffer_new(bh);
Linus Torvalds45bce8f2012-11-29 10:21:43 -08002064
2065 block_start = block_end;
2066 bh = bh->b_this_page;
2067 } while (bh != head);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002068
2069 /*
2070 * If this is a partial write which happened to make all buffers
2071 * uptodate then we can optimize away a bogus readpage() for
2072 * the next read(). Here we 'discover' whether the page went
2073 * uptodate as a result of this (potentially partial) write.
2074 */
2075 if (!partial)
2076 SetPageUptodate(page);
2077 return 0;
2078}
2079
2080/*
Christoph Hellwig155130a2010-06-04 11:29:58 +02002081 * block_write_begin takes care of the basic task of block allocation and
2082 * bringing partial write blocks uptodate first.
2083 *
npiggin@suse.de7bb46a62010-05-27 01:05:33 +10002084 * The filesystem needs to handle block truncation upon failure.
Nick Pigginafddba42007-10-16 01:25:01 -07002085 */
Christoph Hellwig155130a2010-06-04 11:29:58 +02002086int block_write_begin(struct address_space *mapping, loff_t pos, unsigned len,
2087 unsigned flags, struct page **pagep, get_block_t *get_block)
Nick Pigginafddba42007-10-16 01:25:01 -07002088{
Kirill A. Shutemov09cbfea2016-04-01 15:29:47 +03002089 pgoff_t index = pos >> PAGE_SHIFT;
Nick Pigginafddba42007-10-16 01:25:01 -07002090 struct page *page;
Christoph Hellwig6e1db882010-06-04 11:29:57 +02002091 int status;
Nick Pigginafddba42007-10-16 01:25:01 -07002092
Christoph Hellwig6e1db882010-06-04 11:29:57 +02002093 page = grab_cache_page_write_begin(mapping, index, flags);
2094 if (!page)
2095 return -ENOMEM;
Nick Pigginafddba42007-10-16 01:25:01 -07002096
Christoph Hellwig6e1db882010-06-04 11:29:57 +02002097 status = __block_write_begin(page, pos, len, get_block);
Nick Pigginafddba42007-10-16 01:25:01 -07002098 if (unlikely(status)) {
Christoph Hellwig6e1db882010-06-04 11:29:57 +02002099 unlock_page(page);
Kirill A. Shutemov09cbfea2016-04-01 15:29:47 +03002100 put_page(page);
Christoph Hellwig6e1db882010-06-04 11:29:57 +02002101 page = NULL;
Nick Pigginafddba42007-10-16 01:25:01 -07002102 }
2103
Christoph Hellwig6e1db882010-06-04 11:29:57 +02002104 *pagep = page;
Nick Pigginafddba42007-10-16 01:25:01 -07002105 return status;
2106}
2107EXPORT_SYMBOL(block_write_begin);
2108
2109int block_write_end(struct file *file, struct address_space *mapping,
2110 loff_t pos, unsigned len, unsigned copied,
2111 struct page *page, void *fsdata)
2112{
2113 struct inode *inode = mapping->host;
2114 unsigned start;
2115
Kirill A. Shutemov09cbfea2016-04-01 15:29:47 +03002116 start = pos & (PAGE_SIZE - 1);
Nick Pigginafddba42007-10-16 01:25:01 -07002117
2118 if (unlikely(copied < len)) {
2119 /*
2120 * The buffers that were written will now be uptodate, so we
2121 * don't have to worry about a readpage reading them and
2122 * overwriting a partial write. However if we have encountered
2123 * a short write and only partially written into a buffer, it
2124 * will not be marked uptodate, so a readpage might come in and
2125 * destroy our partial write.
2126 *
2127 * Do the simplest thing, and just treat any short write to a
2128 * non uptodate page as a zero-length write, and force the
2129 * caller to redo the whole thing.
2130 */
2131 if (!PageUptodate(page))
2132 copied = 0;
2133
2134 page_zero_new_buffers(page, start+copied, start+len);
2135 }
2136 flush_dcache_page(page);
2137
2138 /* This could be a short (even 0-length) commit */
2139 __block_commit_write(inode, page, start, start+copied);
2140
2141 return copied;
2142}
2143EXPORT_SYMBOL(block_write_end);
2144
2145int generic_write_end(struct file *file, struct address_space *mapping,
2146 loff_t pos, unsigned len, unsigned copied,
2147 struct page *page, void *fsdata)
2148{
2149 struct inode *inode = mapping->host;
Jan Kara90a80202014-10-01 21:49:18 -04002150 loff_t old_size = inode->i_size;
Jan Karac7d206b2008-07-11 19:27:31 -04002151 int i_size_changed = 0;
Nick Pigginafddba42007-10-16 01:25:01 -07002152
2153 copied = block_write_end(file, mapping, pos, len, copied, page, fsdata);
2154
2155 /*
2156 * No need to use i_size_read() here, the i_size
2157 * cannot change under us because we hold i_mutex.
2158 *
2159 * But it's important to update i_size while still holding page lock:
2160 * page writeout could otherwise come in and zero beyond i_size.
2161 */
2162 if (pos+copied > inode->i_size) {
2163 i_size_write(inode, pos+copied);
Jan Karac7d206b2008-07-11 19:27:31 -04002164 i_size_changed = 1;
Nick Pigginafddba42007-10-16 01:25:01 -07002165 }
2166
2167 unlock_page(page);
Kirill A. Shutemov09cbfea2016-04-01 15:29:47 +03002168 put_page(page);
Nick Pigginafddba42007-10-16 01:25:01 -07002169
Jan Kara90a80202014-10-01 21:49:18 -04002170 if (old_size < pos)
2171 pagecache_isize_extended(inode, old_size, pos);
Jan Karac7d206b2008-07-11 19:27:31 -04002172 /*
2173 * Don't mark the inode dirty under page lock. First, it unnecessarily
2174 * makes the holding time of page lock longer. Second, it forces lock
2175 * ordering of page lock and transaction start for journaling
2176 * filesystems.
2177 */
2178 if (i_size_changed)
2179 mark_inode_dirty(inode);
2180
Nick Pigginafddba42007-10-16 01:25:01 -07002181 return copied;
2182}
2183EXPORT_SYMBOL(generic_write_end);
2184
2185/*
Hisashi Hifumi8ab22b92008-07-28 15:46:36 -07002186 * block_is_partially_uptodate checks whether buffers within a page are
2187 * uptodate or not.
2188 *
2189 * Returns true if all buffers which correspond to a file portion
2190 * we want to read are uptodate.
2191 */
Al Viroc186afb42014-02-02 21:16:54 -05002192int block_is_partially_uptodate(struct page *page, unsigned long from,
2193 unsigned long count)
Hisashi Hifumi8ab22b92008-07-28 15:46:36 -07002194{
Hisashi Hifumi8ab22b92008-07-28 15:46:36 -07002195 unsigned block_start, block_end, blocksize;
2196 unsigned to;
2197 struct buffer_head *bh, *head;
2198 int ret = 1;
2199
2200 if (!page_has_buffers(page))
2201 return 0;
2202
Linus Torvalds45bce8f2012-11-29 10:21:43 -08002203 head = page_buffers(page);
2204 blocksize = head->b_size;
Kirill A. Shutemov09cbfea2016-04-01 15:29:47 +03002205 to = min_t(unsigned, PAGE_SIZE - from, count);
Hisashi Hifumi8ab22b92008-07-28 15:46:36 -07002206 to = from + to;
Kirill A. Shutemov09cbfea2016-04-01 15:29:47 +03002207 if (from < blocksize && to > PAGE_SIZE - blocksize)
Hisashi Hifumi8ab22b92008-07-28 15:46:36 -07002208 return 0;
2209
Hisashi Hifumi8ab22b92008-07-28 15:46:36 -07002210 bh = head;
2211 block_start = 0;
2212 do {
2213 block_end = block_start + blocksize;
2214 if (block_end > from && block_start < to) {
2215 if (!buffer_uptodate(bh)) {
2216 ret = 0;
2217 break;
2218 }
2219 if (block_end >= to)
2220 break;
2221 }
2222 block_start = block_end;
2223 bh = bh->b_this_page;
2224 } while (bh != head);
2225
2226 return ret;
2227}
2228EXPORT_SYMBOL(block_is_partially_uptodate);
2229
2230/*
Linus Torvalds1da177e2005-04-16 15:20:36 -07002231 * Generic "read page" function for block devices that have the normal
2232 * get_block functionality. This is most of the block device filesystems.
2233 * Reads the page asynchronously --- the unlock_buffer() and
2234 * set/clear_buffer_uptodate() functions propagate buffer state into the
2235 * page struct once IO has completed.
2236 */
2237int block_read_full_page(struct page *page, get_block_t *get_block)
2238{
2239 struct inode *inode = page->mapping->host;
2240 sector_t iblock, lblock;
2241 struct buffer_head *bh, *head, *arr[MAX_BUF_PER_PAGE];
Linus Torvalds45bce8f2012-11-29 10:21:43 -08002242 unsigned int blocksize, bbits;
Linus Torvalds1da177e2005-04-16 15:20:36 -07002243 int nr, i;
2244 int fully_mapped = 1;
2245
Linus Torvalds45bce8f2012-11-29 10:21:43 -08002246 head = create_page_buffers(page, inode, 0);
2247 blocksize = head->b_size;
2248 bbits = block_size_bits(blocksize);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002249
Kirill A. Shutemov09cbfea2016-04-01 15:29:47 +03002250 iblock = (sector_t)page->index << (PAGE_SHIFT - bbits);
Linus Torvalds45bce8f2012-11-29 10:21:43 -08002251 lblock = (i_size_read(inode)+blocksize-1) >> bbits;
Linus Torvalds1da177e2005-04-16 15:20:36 -07002252 bh = head;
2253 nr = 0;
2254 i = 0;
2255
2256 do {
2257 if (buffer_uptodate(bh))
2258 continue;
2259
2260 if (!buffer_mapped(bh)) {
Andrew Mortonc64610b2005-05-16 21:53:49 -07002261 int err = 0;
2262
Linus Torvalds1da177e2005-04-16 15:20:36 -07002263 fully_mapped = 0;
2264 if (iblock < lblock) {
Badari Pulavartyb0cf2322006-03-26 01:38:00 -08002265 WARN_ON(bh->b_size != blocksize);
Andrew Mortonc64610b2005-05-16 21:53:49 -07002266 err = get_block(inode, iblock, bh, 0);
2267 if (err)
Linus Torvalds1da177e2005-04-16 15:20:36 -07002268 SetPageError(page);
2269 }
2270 if (!buffer_mapped(bh)) {
Christoph Lametereebd2aa2008-02-04 22:28:29 -08002271 zero_user(page, i * blocksize, blocksize);
Andrew Mortonc64610b2005-05-16 21:53:49 -07002272 if (!err)
2273 set_buffer_uptodate(bh);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002274 continue;
2275 }
2276 /*
2277 * get_block() might have updated the buffer
2278 * synchronously
2279 */
2280 if (buffer_uptodate(bh))
2281 continue;
2282 }
2283 arr[nr++] = bh;
2284 } while (i++, iblock++, (bh = bh->b_this_page) != head);
2285
2286 if (fully_mapped)
2287 SetPageMappedToDisk(page);
2288
2289 if (!nr) {
2290 /*
2291 * All buffers are uptodate - we can set the page uptodate
2292 * as well. But not if get_block() returned an error.
2293 */
2294 if (!PageError(page))
2295 SetPageUptodate(page);
2296 unlock_page(page);
2297 return 0;
2298 }
2299
2300 /* Stage two: lock the buffers */
2301 for (i = 0; i < nr; i++) {
2302 bh = arr[i];
2303 lock_buffer(bh);
2304 mark_buffer_async_read(bh);
2305 }
2306
2307 /*
2308 * Stage 3: start the IO. Check for uptodateness
2309 * inside the buffer lock in case another process reading
2310 * the underlying blockdev brought it uptodate (the sct fix).
2311 */
2312 for (i = 0; i < nr; i++) {
2313 bh = arr[i];
2314 if (buffer_uptodate(bh))
2315 end_buffer_async_read(bh, 1);
2316 else
Mike Christie2a222ca2016-06-05 14:31:43 -05002317 submit_bh(REQ_OP_READ, 0, bh);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002318 }
2319 return 0;
2320}
H Hartley Sweeten1fe72ea2009-09-22 16:43:51 -07002321EXPORT_SYMBOL(block_read_full_page);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002322
2323/* utility function for filesystems that need to do work on expanding
Nick Piggin89e10782007-10-16 01:25:07 -07002324 * truncates. Uses filesystem pagecache writes to allow the filesystem to
Linus Torvalds1da177e2005-04-16 15:20:36 -07002325 * deal with the hole.
2326 */
Nick Piggin89e10782007-10-16 01:25:07 -07002327int generic_cont_expand_simple(struct inode *inode, loff_t size)
Linus Torvalds1da177e2005-04-16 15:20:36 -07002328{
2329 struct address_space *mapping = inode->i_mapping;
2330 struct page *page;
Nick Piggin89e10782007-10-16 01:25:07 -07002331 void *fsdata;
Linus Torvalds1da177e2005-04-16 15:20:36 -07002332 int err;
2333
npiggin@suse.dec08d3b02009-08-21 02:35:06 +10002334 err = inode_newsize_ok(inode, size);
2335 if (err)
Linus Torvalds1da177e2005-04-16 15:20:36 -07002336 goto out;
2337
Nick Piggin89e10782007-10-16 01:25:07 -07002338 err = pagecache_write_begin(NULL, mapping, size, 0,
2339 AOP_FLAG_UNINTERRUPTIBLE|AOP_FLAG_CONT_EXPAND,
2340 &page, &fsdata);
2341 if (err)
Linus Torvalds1da177e2005-04-16 15:20:36 -07002342 goto out;
OGAWA Hirofumi05eb0b52006-01-08 01:02:13 -08002343
Nick Piggin89e10782007-10-16 01:25:07 -07002344 err = pagecache_write_end(NULL, mapping, size, 0, 0, page, fsdata);
2345 BUG_ON(err > 0);
OGAWA Hirofumi05eb0b52006-01-08 01:02:13 -08002346
Linus Torvalds1da177e2005-04-16 15:20:36 -07002347out:
2348 return err;
2349}
H Hartley Sweeten1fe72ea2009-09-22 16:43:51 -07002350EXPORT_SYMBOL(generic_cont_expand_simple);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002351
Adrian Bunkf1e3af72008-04-29 00:59:01 -07002352static int cont_expand_zero(struct file *file, struct address_space *mapping,
2353 loff_t pos, loff_t *bytes)
OGAWA Hirofumi05eb0b52006-01-08 01:02:13 -08002354{
Nick Piggin89e10782007-10-16 01:25:07 -07002355 struct inode *inode = mapping->host;
Fabian Frederick61604a22017-02-27 14:28:32 -08002356 unsigned int blocksize = i_blocksize(inode);
Nick Piggin89e10782007-10-16 01:25:07 -07002357 struct page *page;
2358 void *fsdata;
2359 pgoff_t index, curidx;
2360 loff_t curpos;
2361 unsigned zerofrom, offset, len;
2362 int err = 0;
OGAWA Hirofumi05eb0b52006-01-08 01:02:13 -08002363
Kirill A. Shutemov09cbfea2016-04-01 15:29:47 +03002364 index = pos >> PAGE_SHIFT;
2365 offset = pos & ~PAGE_MASK;
Nick Piggin89e10782007-10-16 01:25:07 -07002366
Kirill A. Shutemov09cbfea2016-04-01 15:29:47 +03002367 while (index > (curidx = (curpos = *bytes)>>PAGE_SHIFT)) {
2368 zerofrom = curpos & ~PAGE_MASK;
Nick Piggin89e10782007-10-16 01:25:07 -07002369 if (zerofrom & (blocksize-1)) {
2370 *bytes |= (blocksize-1);
2371 (*bytes)++;
2372 }
Kirill A. Shutemov09cbfea2016-04-01 15:29:47 +03002373 len = PAGE_SIZE - zerofrom;
Nick Piggin89e10782007-10-16 01:25:07 -07002374
2375 err = pagecache_write_begin(file, mapping, curpos, len,
2376 AOP_FLAG_UNINTERRUPTIBLE,
2377 &page, &fsdata);
2378 if (err)
2379 goto out;
Christoph Lametereebd2aa2008-02-04 22:28:29 -08002380 zero_user(page, zerofrom, len);
Nick Piggin89e10782007-10-16 01:25:07 -07002381 err = pagecache_write_end(file, mapping, curpos, len, len,
2382 page, fsdata);
2383 if (err < 0)
2384 goto out;
2385 BUG_ON(err != len);
2386 err = 0;
OGAWA Hirofumi061e9742008-04-28 02:16:28 -07002387
2388 balance_dirty_pages_ratelimited(mapping);
Mikulas Patockac2ca0fc2014-07-27 13:00:41 -04002389
2390 if (unlikely(fatal_signal_pending(current))) {
2391 err = -EINTR;
2392 goto out;
2393 }
Nick Piggin89e10782007-10-16 01:25:07 -07002394 }
2395
2396 /* page covers the boundary, find the boundary offset */
2397 if (index == curidx) {
Kirill A. Shutemov09cbfea2016-04-01 15:29:47 +03002398 zerofrom = curpos & ~PAGE_MASK;
Nick Piggin89e10782007-10-16 01:25:07 -07002399 /* if we will expand the thing last block will be filled */
2400 if (offset <= zerofrom) {
2401 goto out;
2402 }
2403 if (zerofrom & (blocksize-1)) {
2404 *bytes |= (blocksize-1);
2405 (*bytes)++;
2406 }
2407 len = offset - zerofrom;
2408
2409 err = pagecache_write_begin(file, mapping, curpos, len,
2410 AOP_FLAG_UNINTERRUPTIBLE,
2411 &page, &fsdata);
2412 if (err)
2413 goto out;
Christoph Lametereebd2aa2008-02-04 22:28:29 -08002414 zero_user(page, zerofrom, len);
Nick Piggin89e10782007-10-16 01:25:07 -07002415 err = pagecache_write_end(file, mapping, curpos, len, len,
2416 page, fsdata);
2417 if (err < 0)
2418 goto out;
2419 BUG_ON(err != len);
2420 err = 0;
2421 }
2422out:
2423 return err;
OGAWA Hirofumi05eb0b52006-01-08 01:02:13 -08002424}
2425
Linus Torvalds1da177e2005-04-16 15:20:36 -07002426/*
2427 * For moronic filesystems that do not allow holes in file.
2428 * We may have to extend the file.
2429 */
Christoph Hellwig282dc172010-06-04 11:29:55 +02002430int cont_write_begin(struct file *file, struct address_space *mapping,
Nick Piggin89e10782007-10-16 01:25:07 -07002431 loff_t pos, unsigned len, unsigned flags,
2432 struct page **pagep, void **fsdata,
2433 get_block_t *get_block, loff_t *bytes)
Linus Torvalds1da177e2005-04-16 15:20:36 -07002434{
Linus Torvalds1da177e2005-04-16 15:20:36 -07002435 struct inode *inode = mapping->host;
Fabian Frederick61604a22017-02-27 14:28:32 -08002436 unsigned int blocksize = i_blocksize(inode);
2437 unsigned int zerofrom;
Nick Piggin89e10782007-10-16 01:25:07 -07002438 int err;
Linus Torvalds1da177e2005-04-16 15:20:36 -07002439
Nick Piggin89e10782007-10-16 01:25:07 -07002440 err = cont_expand_zero(file, mapping, pos, bytes);
2441 if (err)
Christoph Hellwig155130a2010-06-04 11:29:58 +02002442 return err;
Nick Piggin89e10782007-10-16 01:25:07 -07002443
Kirill A. Shutemov09cbfea2016-04-01 15:29:47 +03002444 zerofrom = *bytes & ~PAGE_MASK;
Nick Piggin89e10782007-10-16 01:25:07 -07002445 if (pos+len > *bytes && zerofrom & (blocksize-1)) {
2446 *bytes |= (blocksize-1);
2447 (*bytes)++;
Linus Torvalds1da177e2005-04-16 15:20:36 -07002448 }
2449
Christoph Hellwig155130a2010-06-04 11:29:58 +02002450 return block_write_begin(mapping, pos, len, flags, pagep, get_block);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002451}
H Hartley Sweeten1fe72ea2009-09-22 16:43:51 -07002452EXPORT_SYMBOL(cont_write_begin);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002453
Linus Torvalds1da177e2005-04-16 15:20:36 -07002454int block_commit_write(struct page *page, unsigned from, unsigned to)
2455{
2456 struct inode *inode = page->mapping->host;
2457 __block_commit_write(inode,page,from,to);
2458 return 0;
2459}
H Hartley Sweeten1fe72ea2009-09-22 16:43:51 -07002460EXPORT_SYMBOL(block_commit_write);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002461
David Chinner54171692007-07-19 17:39:55 +10002462/*
2463 * block_page_mkwrite() is not allowed to change the file size as it gets
2464 * called from a page fault handler when a page is first dirtied. Hence we must
2465 * be careful to check for EOF conditions here. We set the page up correctly
2466 * for a written page which means we get ENOSPC checking when writing into
2467 * holes and correct delalloc and unwritten extent mapping on filesystems that
2468 * support these features.
2469 *
2470 * We are not allowed to take the i_mutex here so we have to play games to
2471 * protect against truncate races as the page could now be beyond EOF. Because
npiggin@suse.de7bb46a62010-05-27 01:05:33 +10002472 * truncate writes the inode size before removing pages, once we have the
David Chinner54171692007-07-19 17:39:55 +10002473 * page lock we can determine safely if the page is beyond EOF. If it is not
2474 * beyond EOF, then the page is guaranteed safe against truncation until we
2475 * unlock the page.
Jan Karaea13a862011-05-24 00:23:35 +02002476 *
Jan Kara14da9202012-06-12 16:20:37 +02002477 * Direct callers of this function should protect against filesystem freezing
Ross Zwisler5c500022015-10-13 16:51:02 -06002478 * using sb_start_pagefault() - sb_end_pagefault() functions.
David Chinner54171692007-07-19 17:39:55 +10002479 */
Ross Zwisler5c500022015-10-13 16:51:02 -06002480int block_page_mkwrite(struct vm_area_struct *vma, struct vm_fault *vmf,
Jan Kara24da4fa2011-05-24 00:23:34 +02002481 get_block_t get_block)
David Chinner54171692007-07-19 17:39:55 +10002482{
Nick Pigginc2ec1752009-03-31 15:23:21 -07002483 struct page *page = vmf->page;
Al Viro496ad9a2013-01-23 17:07:38 -05002484 struct inode *inode = file_inode(vma->vm_file);
David Chinner54171692007-07-19 17:39:55 +10002485 unsigned long end;
2486 loff_t size;
Jan Kara24da4fa2011-05-24 00:23:34 +02002487 int ret;
David Chinner54171692007-07-19 17:39:55 +10002488
2489 lock_page(page);
2490 size = i_size_read(inode);
2491 if ((page->mapping != inode->i_mapping) ||
Nick Piggin18336332007-07-20 00:31:45 -07002492 (page_offset(page) > size)) {
Jan Kara24da4fa2011-05-24 00:23:34 +02002493 /* We overload EFAULT to mean page got truncated */
2494 ret = -EFAULT;
2495 goto out_unlock;
David Chinner54171692007-07-19 17:39:55 +10002496 }
2497
2498 /* page is wholly or partially inside EOF */
Kirill A. Shutemov09cbfea2016-04-01 15:29:47 +03002499 if (((page->index + 1) << PAGE_SHIFT) > size)
2500 end = size & ~PAGE_MASK;
David Chinner54171692007-07-19 17:39:55 +10002501 else
Kirill A. Shutemov09cbfea2016-04-01 15:29:47 +03002502 end = PAGE_SIZE;
David Chinner54171692007-07-19 17:39:55 +10002503
Christoph Hellwigebdec242010-10-06 10:47:23 +02002504 ret = __block_write_begin(page, 0, end, get_block);
David Chinner54171692007-07-19 17:39:55 +10002505 if (!ret)
2506 ret = block_commit_write(page, 0, end);
2507
Jan Kara24da4fa2011-05-24 00:23:34 +02002508 if (unlikely(ret < 0))
2509 goto out_unlock;
Jan Karaea13a862011-05-24 00:23:35 +02002510 set_page_dirty(page);
Darrick J. Wong1d1d1a72013-02-21 16:42:51 -08002511 wait_for_stable_page(page);
Jan Kara24da4fa2011-05-24 00:23:34 +02002512 return 0;
2513out_unlock:
2514 unlock_page(page);
David Chinner54171692007-07-19 17:39:55 +10002515 return ret;
2516}
H Hartley Sweeten1fe72ea2009-09-22 16:43:51 -07002517EXPORT_SYMBOL(block_page_mkwrite);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002518
2519/*
Nick Piggin03158cd2007-10-16 01:25:25 -07002520 * nobh_write_begin()'s prereads are special: the buffer_heads are freed
Linus Torvalds1da177e2005-04-16 15:20:36 -07002521 * immediately, while under the page lock. So it needs a special end_io
2522 * handler which does not touch the bh after unlocking it.
Linus Torvalds1da177e2005-04-16 15:20:36 -07002523 */
2524static void end_buffer_read_nobh(struct buffer_head *bh, int uptodate)
2525{
Dmitry Monakhov68671f32007-10-16 01:24:47 -07002526 __end_buffer_read_notouch(bh, uptodate);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002527}
2528
2529/*
Nick Piggin03158cd2007-10-16 01:25:25 -07002530 * Attach the singly-linked list of buffers created by nobh_write_begin, to
2531 * the page (converting it to circular linked list and taking care of page
2532 * dirty races).
2533 */
2534static void attach_nobh_buffers(struct page *page, struct buffer_head *head)
2535{
2536 struct buffer_head *bh;
2537
2538 BUG_ON(!PageLocked(page));
2539
2540 spin_lock(&page->mapping->private_lock);
2541 bh = head;
2542 do {
2543 if (PageDirty(page))
2544 set_buffer_dirty(bh);
2545 if (!bh->b_this_page)
2546 bh->b_this_page = head;
2547 bh = bh->b_this_page;
2548 } while (bh != head);
2549 attach_page_buffers(page, head);
2550 spin_unlock(&page->mapping->private_lock);
2551}
2552
2553/*
Christoph Hellwigea0f04e2010-06-04 11:29:54 +02002554 * On entry, the page is fully not uptodate.
2555 * On exit the page is fully uptodate in the areas outside (from,to)
npiggin@suse.de7bb46a62010-05-27 01:05:33 +10002556 * The filesystem needs to handle block truncation upon failure.
Linus Torvalds1da177e2005-04-16 15:20:36 -07002557 */
Christoph Hellwigea0f04e2010-06-04 11:29:54 +02002558int nobh_write_begin(struct address_space *mapping,
Nick Piggin03158cd2007-10-16 01:25:25 -07002559 loff_t pos, unsigned len, unsigned flags,
2560 struct page **pagep, void **fsdata,
Linus Torvalds1da177e2005-04-16 15:20:36 -07002561 get_block_t *get_block)
2562{
Nick Piggin03158cd2007-10-16 01:25:25 -07002563 struct inode *inode = mapping->host;
Linus Torvalds1da177e2005-04-16 15:20:36 -07002564 const unsigned blkbits = inode->i_blkbits;
2565 const unsigned blocksize = 1 << blkbits;
Nick Piggina4b06722007-10-16 01:24:48 -07002566 struct buffer_head *head, *bh;
Nick Piggin03158cd2007-10-16 01:25:25 -07002567 struct page *page;
2568 pgoff_t index;
2569 unsigned from, to;
Linus Torvalds1da177e2005-04-16 15:20:36 -07002570 unsigned block_in_page;
Nick Piggina4b06722007-10-16 01:24:48 -07002571 unsigned block_start, block_end;
Linus Torvalds1da177e2005-04-16 15:20:36 -07002572 sector_t block_in_file;
Linus Torvalds1da177e2005-04-16 15:20:36 -07002573 int nr_reads = 0;
Linus Torvalds1da177e2005-04-16 15:20:36 -07002574 int ret = 0;
2575 int is_mapped_to_disk = 1;
Linus Torvalds1da177e2005-04-16 15:20:36 -07002576
Kirill A. Shutemov09cbfea2016-04-01 15:29:47 +03002577 index = pos >> PAGE_SHIFT;
2578 from = pos & (PAGE_SIZE - 1);
Nick Piggin03158cd2007-10-16 01:25:25 -07002579 to = from + len;
2580
Nick Piggin54566b22009-01-04 12:00:53 -08002581 page = grab_cache_page_write_begin(mapping, index, flags);
Nick Piggin03158cd2007-10-16 01:25:25 -07002582 if (!page)
2583 return -ENOMEM;
2584 *pagep = page;
2585 *fsdata = NULL;
2586
2587 if (page_has_buffers(page)) {
Namhyung Kim309f77a2010-10-25 15:01:12 +09002588 ret = __block_write_begin(page, pos, len, get_block);
2589 if (unlikely(ret))
2590 goto out_release;
2591 return ret;
Nick Piggin03158cd2007-10-16 01:25:25 -07002592 }
Nick Piggina4b06722007-10-16 01:24:48 -07002593
Linus Torvalds1da177e2005-04-16 15:20:36 -07002594 if (PageMappedToDisk(page))
2595 return 0;
2596
Nick Piggina4b06722007-10-16 01:24:48 -07002597 /*
2598 * Allocate buffers so that we can keep track of state, and potentially
2599 * attach them to the page if an error occurs. In the common case of
2600 * no error, they will just be freed again without ever being attached
2601 * to the page (which is all OK, because we're under the page lock).
2602 *
2603 * Be careful: the buffer linked list is a NULL terminated one, rather
2604 * than the circular one we're used to.
2605 */
2606 head = alloc_page_buffers(page, blocksize, 0);
Nick Piggin03158cd2007-10-16 01:25:25 -07002607 if (!head) {
2608 ret = -ENOMEM;
2609 goto out_release;
2610 }
Nick Piggina4b06722007-10-16 01:24:48 -07002611
Kirill A. Shutemov09cbfea2016-04-01 15:29:47 +03002612 block_in_file = (sector_t)page->index << (PAGE_SHIFT - blkbits);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002613
2614 /*
2615 * We loop across all blocks in the page, whether or not they are
2616 * part of the affected region. This is so we can discover if the
2617 * page is fully mapped-to-disk.
2618 */
Nick Piggina4b06722007-10-16 01:24:48 -07002619 for (block_start = 0, block_in_page = 0, bh = head;
Kirill A. Shutemov09cbfea2016-04-01 15:29:47 +03002620 block_start < PAGE_SIZE;
Nick Piggina4b06722007-10-16 01:24:48 -07002621 block_in_page++, block_start += blocksize, bh = bh->b_this_page) {
Linus Torvalds1da177e2005-04-16 15:20:36 -07002622 int create;
2623
Nick Piggina4b06722007-10-16 01:24:48 -07002624 block_end = block_start + blocksize;
2625 bh->b_state = 0;
Linus Torvalds1da177e2005-04-16 15:20:36 -07002626 create = 1;
2627 if (block_start >= to)
2628 create = 0;
2629 ret = get_block(inode, block_in_file + block_in_page,
Nick Piggina4b06722007-10-16 01:24:48 -07002630 bh, create);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002631 if (ret)
2632 goto failed;
Nick Piggina4b06722007-10-16 01:24:48 -07002633 if (!buffer_mapped(bh))
Linus Torvalds1da177e2005-04-16 15:20:36 -07002634 is_mapped_to_disk = 0;
Nick Piggina4b06722007-10-16 01:24:48 -07002635 if (buffer_new(bh))
2636 unmap_underlying_metadata(bh->b_bdev, bh->b_blocknr);
2637 if (PageUptodate(page)) {
2638 set_buffer_uptodate(bh);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002639 continue;
Nick Piggina4b06722007-10-16 01:24:48 -07002640 }
2641 if (buffer_new(bh) || !buffer_mapped(bh)) {
Christoph Lametereebd2aa2008-02-04 22:28:29 -08002642 zero_user_segments(page, block_start, from,
2643 to, block_end);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002644 continue;
2645 }
Nick Piggina4b06722007-10-16 01:24:48 -07002646 if (buffer_uptodate(bh))
Linus Torvalds1da177e2005-04-16 15:20:36 -07002647 continue; /* reiserfs does this */
2648 if (block_start < from || block_end > to) {
Nick Piggina4b06722007-10-16 01:24:48 -07002649 lock_buffer(bh);
2650 bh->b_end_io = end_buffer_read_nobh;
Mike Christie2a222ca2016-06-05 14:31:43 -05002651 submit_bh(REQ_OP_READ, 0, bh);
Nick Piggina4b06722007-10-16 01:24:48 -07002652 nr_reads++;
Linus Torvalds1da177e2005-04-16 15:20:36 -07002653 }
2654 }
2655
2656 if (nr_reads) {
Linus Torvalds1da177e2005-04-16 15:20:36 -07002657 /*
2658 * The page is locked, so these buffers are protected from
2659 * any VM or truncate activity. Hence we don't need to care
2660 * for the buffer_head refcounts.
2661 */
Nick Piggina4b06722007-10-16 01:24:48 -07002662 for (bh = head; bh; bh = bh->b_this_page) {
Linus Torvalds1da177e2005-04-16 15:20:36 -07002663 wait_on_buffer(bh);
2664 if (!buffer_uptodate(bh))
2665 ret = -EIO;
Linus Torvalds1da177e2005-04-16 15:20:36 -07002666 }
2667 if (ret)
2668 goto failed;
2669 }
2670
2671 if (is_mapped_to_disk)
2672 SetPageMappedToDisk(page);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002673
Nick Piggin03158cd2007-10-16 01:25:25 -07002674 *fsdata = head; /* to be released by nobh_write_end */
Nick Piggina4b06722007-10-16 01:24:48 -07002675
Linus Torvalds1da177e2005-04-16 15:20:36 -07002676 return 0;
2677
2678failed:
Nick Piggin03158cd2007-10-16 01:25:25 -07002679 BUG_ON(!ret);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002680 /*
Nick Piggina4b06722007-10-16 01:24:48 -07002681 * Error recovery is a bit difficult. We need to zero out blocks that
2682 * were newly allocated, and dirty them to ensure they get written out.
2683 * Buffers need to be attached to the page at this point, otherwise
2684 * the handling of potential IO errors during writeout would be hard
2685 * (could try doing synchronous writeout, but what if that fails too?)
Linus Torvalds1da177e2005-04-16 15:20:36 -07002686 */
Nick Piggin03158cd2007-10-16 01:25:25 -07002687 attach_nobh_buffers(page, head);
2688 page_zero_new_buffers(page, from, to);
Nick Piggina4b06722007-10-16 01:24:48 -07002689
Nick Piggin03158cd2007-10-16 01:25:25 -07002690out_release:
2691 unlock_page(page);
Kirill A. Shutemov09cbfea2016-04-01 15:29:47 +03002692 put_page(page);
Nick Piggin03158cd2007-10-16 01:25:25 -07002693 *pagep = NULL;
Nick Piggina4b06722007-10-16 01:24:48 -07002694
npiggin@suse.de7bb46a62010-05-27 01:05:33 +10002695 return ret;
2696}
Nick Piggin03158cd2007-10-16 01:25:25 -07002697EXPORT_SYMBOL(nobh_write_begin);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002698
Nick Piggin03158cd2007-10-16 01:25:25 -07002699int nobh_write_end(struct file *file, struct address_space *mapping,
2700 loff_t pos, unsigned len, unsigned copied,
2701 struct page *page, void *fsdata)
Linus Torvalds1da177e2005-04-16 15:20:36 -07002702{
2703 struct inode *inode = page->mapping->host;
Nick Pigginefdc3132007-10-21 06:57:41 +02002704 struct buffer_head *head = fsdata;
Nick Piggin03158cd2007-10-16 01:25:25 -07002705 struct buffer_head *bh;
Dmitri Monakhov5b41e742008-03-28 14:15:52 -07002706 BUG_ON(fsdata != NULL && page_has_buffers(page));
Linus Torvalds1da177e2005-04-16 15:20:36 -07002707
Dave Kleikampd4cf1092009-02-06 14:59:26 -06002708 if (unlikely(copied < len) && head)
Dmitri Monakhov5b41e742008-03-28 14:15:52 -07002709 attach_nobh_buffers(page, head);
2710 if (page_has_buffers(page))
2711 return generic_write_end(file, mapping, pos, len,
2712 copied, page, fsdata);
Nick Piggina4b06722007-10-16 01:24:48 -07002713
Nick Piggin22c8ca72007-02-20 13:58:09 -08002714 SetPageUptodate(page);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002715 set_page_dirty(page);
Nick Piggin03158cd2007-10-16 01:25:25 -07002716 if (pos+copied > inode->i_size) {
2717 i_size_write(inode, pos+copied);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002718 mark_inode_dirty(inode);
2719 }
Nick Piggin03158cd2007-10-16 01:25:25 -07002720
2721 unlock_page(page);
Kirill A. Shutemov09cbfea2016-04-01 15:29:47 +03002722 put_page(page);
Nick Piggin03158cd2007-10-16 01:25:25 -07002723
Nick Piggin03158cd2007-10-16 01:25:25 -07002724 while (head) {
2725 bh = head;
2726 head = head->b_this_page;
2727 free_buffer_head(bh);
2728 }
2729
2730 return copied;
Linus Torvalds1da177e2005-04-16 15:20:36 -07002731}
Nick Piggin03158cd2007-10-16 01:25:25 -07002732EXPORT_SYMBOL(nobh_write_end);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002733
2734/*
2735 * nobh_writepage() - based on block_full_write_page() except
2736 * that it tries to operate without attaching bufferheads to
2737 * the page.
2738 */
2739int nobh_writepage(struct page *page, get_block_t *get_block,
2740 struct writeback_control *wbc)
2741{
2742 struct inode * const inode = page->mapping->host;
2743 loff_t i_size = i_size_read(inode);
Kirill A. Shutemov09cbfea2016-04-01 15:29:47 +03002744 const pgoff_t end_index = i_size >> PAGE_SHIFT;
Linus Torvalds1da177e2005-04-16 15:20:36 -07002745 unsigned offset;
Linus Torvalds1da177e2005-04-16 15:20:36 -07002746 int ret;
2747
2748 /* Is the page fully inside i_size? */
2749 if (page->index < end_index)
2750 goto out;
2751
2752 /* Is the page fully outside i_size? (truncate in progress) */
Kirill A. Shutemov09cbfea2016-04-01 15:29:47 +03002753 offset = i_size & (PAGE_SIZE-1);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002754 if (page->index >= end_index+1 || !offset) {
2755 /*
2756 * The page may have dirty, unmapped buffers. For example,
2757 * they may have been added in ext3_writepage(). Make them
2758 * freeable here, so the page does not leak.
2759 */
2760#if 0
2761 /* Not really sure about this - do we need this ? */
2762 if (page->mapping->a_ops->invalidatepage)
2763 page->mapping->a_ops->invalidatepage(page, offset);
2764#endif
2765 unlock_page(page);
2766 return 0; /* don't care */
2767 }
2768
2769 /*
2770 * The page straddles i_size. It must be zeroed out on each and every
2771 * writepage invocation because it may be mmapped. "A file is mapped
2772 * in multiples of the page size. For a file that is not a multiple of
2773 * the page size, the remaining memory is zeroed when mapped, and
2774 * writes to that region are not written out to the file."
2775 */
Kirill A. Shutemov09cbfea2016-04-01 15:29:47 +03002776 zero_user_segment(page, offset, PAGE_SIZE);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002777out:
2778 ret = mpage_writepage(page, get_block, wbc);
2779 if (ret == -EAGAIN)
Chris Mason35c80d52009-04-15 13:22:38 -04002780 ret = __block_write_full_page(inode, page, get_block, wbc,
2781 end_buffer_async_write);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002782 return ret;
2783}
2784EXPORT_SYMBOL(nobh_writepage);
2785
Nick Piggin03158cd2007-10-16 01:25:25 -07002786int nobh_truncate_page(struct address_space *mapping,
2787 loff_t from, get_block_t *get_block)
Linus Torvalds1da177e2005-04-16 15:20:36 -07002788{
Kirill A. Shutemov09cbfea2016-04-01 15:29:47 +03002789 pgoff_t index = from >> PAGE_SHIFT;
2790 unsigned offset = from & (PAGE_SIZE-1);
Nick Piggin03158cd2007-10-16 01:25:25 -07002791 unsigned blocksize;
2792 sector_t iblock;
2793 unsigned length, pos;
2794 struct inode *inode = mapping->host;
Linus Torvalds1da177e2005-04-16 15:20:36 -07002795 struct page *page;
Nick Piggin03158cd2007-10-16 01:25:25 -07002796 struct buffer_head map_bh;
2797 int err;
Linus Torvalds1da177e2005-04-16 15:20:36 -07002798
Fabian Frederick61604a22017-02-27 14:28:32 -08002799 blocksize = i_blocksize(inode);
Nick Piggin03158cd2007-10-16 01:25:25 -07002800 length = offset & (blocksize - 1);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002801
Nick Piggin03158cd2007-10-16 01:25:25 -07002802 /* Block boundary? Nothing to do */
2803 if (!length)
2804 return 0;
2805
2806 length = blocksize - length;
Kirill A. Shutemov09cbfea2016-04-01 15:29:47 +03002807 iblock = (sector_t)index << (PAGE_SHIFT - inode->i_blkbits);
Nick Piggin03158cd2007-10-16 01:25:25 -07002808
Linus Torvalds1da177e2005-04-16 15:20:36 -07002809 page = grab_cache_page(mapping, index);
Nick Piggin03158cd2007-10-16 01:25:25 -07002810 err = -ENOMEM;
Linus Torvalds1da177e2005-04-16 15:20:36 -07002811 if (!page)
2812 goto out;
2813
Nick Piggin03158cd2007-10-16 01:25:25 -07002814 if (page_has_buffers(page)) {
2815has_buffers:
2816 unlock_page(page);
Kirill A. Shutemov09cbfea2016-04-01 15:29:47 +03002817 put_page(page);
Nick Piggin03158cd2007-10-16 01:25:25 -07002818 return block_truncate_page(mapping, from, get_block);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002819 }
Nick Piggin03158cd2007-10-16 01:25:25 -07002820
2821 /* Find the buffer that contains "offset" */
2822 pos = blocksize;
2823 while (offset >= pos) {
2824 iblock++;
2825 pos += blocksize;
2826 }
2827
Theodore Ts'o460bcf52009-05-12 07:37:56 -04002828 map_bh.b_size = blocksize;
2829 map_bh.b_state = 0;
Nick Piggin03158cd2007-10-16 01:25:25 -07002830 err = get_block(inode, iblock, &map_bh, 0);
2831 if (err)
2832 goto unlock;
2833 /* unmapped? It's a hole - nothing to do */
2834 if (!buffer_mapped(&map_bh))
2835 goto unlock;
2836
2837 /* Ok, it's mapped. Make sure it's up-to-date */
2838 if (!PageUptodate(page)) {
2839 err = mapping->a_ops->readpage(NULL, page);
2840 if (err) {
Kirill A. Shutemov09cbfea2016-04-01 15:29:47 +03002841 put_page(page);
Nick Piggin03158cd2007-10-16 01:25:25 -07002842 goto out;
2843 }
2844 lock_page(page);
2845 if (!PageUptodate(page)) {
2846 err = -EIO;
2847 goto unlock;
2848 }
2849 if (page_has_buffers(page))
2850 goto has_buffers;
2851 }
Christoph Lametereebd2aa2008-02-04 22:28:29 -08002852 zero_user(page, offset, length);
Nick Piggin03158cd2007-10-16 01:25:25 -07002853 set_page_dirty(page);
2854 err = 0;
2855
2856unlock:
Linus Torvalds1da177e2005-04-16 15:20:36 -07002857 unlock_page(page);
Kirill A. Shutemov09cbfea2016-04-01 15:29:47 +03002858 put_page(page);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002859out:
Nick Piggin03158cd2007-10-16 01:25:25 -07002860 return err;
Linus Torvalds1da177e2005-04-16 15:20:36 -07002861}
2862EXPORT_SYMBOL(nobh_truncate_page);
2863
2864int block_truncate_page(struct address_space *mapping,
2865 loff_t from, get_block_t *get_block)
2866{
Kirill A. Shutemov09cbfea2016-04-01 15:29:47 +03002867 pgoff_t index = from >> PAGE_SHIFT;
2868 unsigned offset = from & (PAGE_SIZE-1);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002869 unsigned blocksize;
Andrew Morton54b21a72006-01-08 01:03:05 -08002870 sector_t iblock;
Linus Torvalds1da177e2005-04-16 15:20:36 -07002871 unsigned length, pos;
2872 struct inode *inode = mapping->host;
2873 struct page *page;
2874 struct buffer_head *bh;
Linus Torvalds1da177e2005-04-16 15:20:36 -07002875 int err;
2876
Fabian Frederick61604a22017-02-27 14:28:32 -08002877 blocksize = i_blocksize(inode);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002878 length = offset & (blocksize - 1);
2879
2880 /* Block boundary? Nothing to do */
2881 if (!length)
2882 return 0;
2883
2884 length = blocksize - length;
Kirill A. Shutemov09cbfea2016-04-01 15:29:47 +03002885 iblock = (sector_t)index << (PAGE_SHIFT - inode->i_blkbits);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002886
2887 page = grab_cache_page(mapping, index);
2888 err = -ENOMEM;
2889 if (!page)
2890 goto out;
2891
2892 if (!page_has_buffers(page))
2893 create_empty_buffers(page, blocksize, 0);
2894
2895 /* Find the buffer that contains "offset" */
2896 bh = page_buffers(page);
2897 pos = blocksize;
2898 while (offset >= pos) {
2899 bh = bh->b_this_page;
2900 iblock++;
2901 pos += blocksize;
2902 }
2903
2904 err = 0;
2905 if (!buffer_mapped(bh)) {
Badari Pulavartyb0cf2322006-03-26 01:38:00 -08002906 WARN_ON(bh->b_size != blocksize);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002907 err = get_block(inode, iblock, bh, 0);
2908 if (err)
2909 goto unlock;
2910 /* unmapped? It's a hole - nothing to do */
2911 if (!buffer_mapped(bh))
2912 goto unlock;
2913 }
2914
2915 /* Ok, it's mapped. Make sure it's up-to-date */
2916 if (PageUptodate(page))
2917 set_buffer_uptodate(bh);
2918
David Chinner33a266d2007-02-12 00:51:41 -08002919 if (!buffer_uptodate(bh) && !buffer_delay(bh) && !buffer_unwritten(bh)) {
Linus Torvalds1da177e2005-04-16 15:20:36 -07002920 err = -EIO;
Mike Christiedfec8a12016-06-05 14:31:44 -05002921 ll_rw_block(REQ_OP_READ, 0, 1, &bh);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002922 wait_on_buffer(bh);
2923 /* Uhhuh. Read error. Complain and punt. */
2924 if (!buffer_uptodate(bh))
2925 goto unlock;
2926 }
2927
Christoph Lametereebd2aa2008-02-04 22:28:29 -08002928 zero_user(page, offset, length);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002929 mark_buffer_dirty(bh);
2930 err = 0;
2931
2932unlock:
2933 unlock_page(page);
Kirill A. Shutemov09cbfea2016-04-01 15:29:47 +03002934 put_page(page);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002935out:
2936 return err;
2937}
H Hartley Sweeten1fe72ea2009-09-22 16:43:51 -07002938EXPORT_SYMBOL(block_truncate_page);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002939
2940/*
2941 * The generic ->writepage function for buffer-backed address_spaces
2942 */
Matthew Wilcox1b938c02014-06-04 16:07:43 -07002943int block_write_full_page(struct page *page, get_block_t *get_block,
2944 struct writeback_control *wbc)
Linus Torvalds1da177e2005-04-16 15:20:36 -07002945{
2946 struct inode * const inode = page->mapping->host;
2947 loff_t i_size = i_size_read(inode);
Kirill A. Shutemov09cbfea2016-04-01 15:29:47 +03002948 const pgoff_t end_index = i_size >> PAGE_SHIFT;
Linus Torvalds1da177e2005-04-16 15:20:36 -07002949 unsigned offset;
Linus Torvalds1da177e2005-04-16 15:20:36 -07002950
2951 /* Is the page fully inside i_size? */
2952 if (page->index < end_index)
Chris Mason35c80d52009-04-15 13:22:38 -04002953 return __block_write_full_page(inode, page, get_block, wbc,
Matthew Wilcox1b938c02014-06-04 16:07:43 -07002954 end_buffer_async_write);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002955
2956 /* Is the page fully outside i_size? (truncate in progress) */
Kirill A. Shutemov09cbfea2016-04-01 15:29:47 +03002957 offset = i_size & (PAGE_SIZE-1);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002958 if (page->index >= end_index+1 || !offset) {
2959 /*
2960 * The page may have dirty, unmapped buffers. For example,
2961 * they may have been added in ext3_writepage(). Make them
2962 * freeable here, so the page does not leak.
2963 */
Kirill A. Shutemov09cbfea2016-04-01 15:29:47 +03002964 do_invalidatepage(page, 0, PAGE_SIZE);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002965 unlock_page(page);
2966 return 0; /* don't care */
2967 }
2968
2969 /*
2970 * The page straddles i_size. It must be zeroed out on each and every
Adam Buchbinder2a61aa42009-12-11 16:35:40 -05002971 * writepage invocation because it may be mmapped. "A file is mapped
Linus Torvalds1da177e2005-04-16 15:20:36 -07002972 * in multiples of the page size. For a file that is not a multiple of
2973 * the page size, the remaining memory is zeroed when mapped, and
2974 * writes to that region are not written out to the file."
2975 */
Kirill A. Shutemov09cbfea2016-04-01 15:29:47 +03002976 zero_user_segment(page, offset, PAGE_SIZE);
Matthew Wilcox1b938c02014-06-04 16:07:43 -07002977 return __block_write_full_page(inode, page, get_block, wbc,
2978 end_buffer_async_write);
Chris Mason35c80d52009-04-15 13:22:38 -04002979}
H Hartley Sweeten1fe72ea2009-09-22 16:43:51 -07002980EXPORT_SYMBOL(block_write_full_page);
Chris Mason35c80d52009-04-15 13:22:38 -04002981
Linus Torvalds1da177e2005-04-16 15:20:36 -07002982sector_t generic_block_bmap(struct address_space *mapping, sector_t block,
2983 get_block_t *get_block)
2984{
2985 struct buffer_head tmp;
2986 struct inode *inode = mapping->host;
2987 tmp.b_state = 0;
2988 tmp.b_blocknr = 0;
Fabian Frederick61604a22017-02-27 14:28:32 -08002989 tmp.b_size = i_blocksize(inode);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002990 get_block(inode, block, &tmp, 0);
2991 return tmp.b_blocknr;
2992}
H Hartley Sweeten1fe72ea2009-09-22 16:43:51 -07002993EXPORT_SYMBOL(generic_block_bmap);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002994
Christoph Hellwig4246a0b2015-07-20 15:29:37 +02002995static void end_bio_bh_io_sync(struct bio *bio)
Linus Torvalds1da177e2005-04-16 15:20:36 -07002996{
2997 struct buffer_head *bh = bio->bi_private;
2998
Jens Axboeb7c44ed2015-07-24 12:37:59 -06002999 if (unlikely(bio_flagged(bio, BIO_QUIET)))
Keith Mannthey08bafc02008-11-25 10:24:35 +01003000 set_bit(BH_Quiet, &bh->b_state);
3001
Christoph Hellwig4246a0b2015-07-20 15:29:37 +02003002 bh->b_end_io(bh, !bio->bi_error);
Linus Torvalds1da177e2005-04-16 15:20:36 -07003003 bio_put(bio);
Linus Torvalds1da177e2005-04-16 15:20:36 -07003004}
3005
Linus Torvalds57302e02012-12-04 08:25:11 -08003006/*
3007 * This allows us to do IO even on the odd last sectors
Akinobu Mita59d43912014-10-09 15:26:53 -07003008 * of a device, even if the block size is some multiple
Linus Torvalds57302e02012-12-04 08:25:11 -08003009 * of the physical sector size.
3010 *
3011 * We'll just truncate the bio to the size of the device,
3012 * and clear the end of the buffer head manually.
3013 *
3014 * Truly out-of-range accesses will turn into actual IO
3015 * errors, this only handles the "we need to be able to
3016 * do IO at the final sector" case.
3017 */
Mike Christie2a222ca2016-06-05 14:31:43 -05003018void guard_bio_eod(int op, struct bio *bio)
Linus Torvalds57302e02012-12-04 08:25:11 -08003019{
3020 sector_t maxsector;
Akinobu Mita59d43912014-10-09 15:26:53 -07003021 struct bio_vec *bvec = &bio->bi_io_vec[bio->bi_vcnt - 1];
3022 unsigned truncated_bytes;
Linus Torvalds57302e02012-12-04 08:25:11 -08003023
3024 maxsector = i_size_read(bio->bi_bdev->bd_inode) >> 9;
3025 if (!maxsector)
3026 return;
3027
3028 /*
3029 * If the *whole* IO is past the end of the device,
3030 * let it through, and the IO layer will turn it into
3031 * an EIO.
3032 */
Kent Overstreet4f024f32013-10-11 15:44:27 -07003033 if (unlikely(bio->bi_iter.bi_sector >= maxsector))
Linus Torvalds57302e02012-12-04 08:25:11 -08003034 return;
3035
Kent Overstreet4f024f32013-10-11 15:44:27 -07003036 maxsector -= bio->bi_iter.bi_sector;
Akinobu Mita59d43912014-10-09 15:26:53 -07003037 if (likely((bio->bi_iter.bi_size >> 9) <= maxsector))
Linus Torvalds57302e02012-12-04 08:25:11 -08003038 return;
3039
Akinobu Mita59d43912014-10-09 15:26:53 -07003040 /* Uhhuh. We've got a bio that straddles the device size! */
3041 truncated_bytes = bio->bi_iter.bi_size - (maxsector << 9);
Linus Torvalds57302e02012-12-04 08:25:11 -08003042
3043 /* Truncate the bio.. */
Akinobu Mita59d43912014-10-09 15:26:53 -07003044 bio->bi_iter.bi_size -= truncated_bytes;
3045 bvec->bv_len -= truncated_bytes;
Linus Torvalds57302e02012-12-04 08:25:11 -08003046
3047 /* ..and clear the end of the buffer for reads */
Mike Christie2a222ca2016-06-05 14:31:43 -05003048 if (op == REQ_OP_READ) {
Akinobu Mita59d43912014-10-09 15:26:53 -07003049 zero_user(bvec->bv_page, bvec->bv_offset + bvec->bv_len,
3050 truncated_bytes);
Linus Torvalds57302e02012-12-04 08:25:11 -08003051 }
3052}
3053
Mike Christie2a222ca2016-06-05 14:31:43 -05003054static int submit_bh_wbc(int op, int op_flags, struct buffer_head *bh,
Tejun Heob16b1de2015-06-02 08:39:48 -06003055 unsigned long bio_flags, struct writeback_control *wbc)
Linus Torvalds1da177e2005-04-16 15:20:36 -07003056{
3057 struct bio *bio;
Linus Torvalds1da177e2005-04-16 15:20:36 -07003058
3059 BUG_ON(!buffer_locked(bh));
3060 BUG_ON(!buffer_mapped(bh));
3061 BUG_ON(!bh->b_end_io);
Aneesh Kumar K.V8fb0e342009-05-12 16:22:37 -04003062 BUG_ON(buffer_delay(bh));
3063 BUG_ON(buffer_unwritten(bh));
Linus Torvalds1da177e2005-04-16 15:20:36 -07003064
Jens Axboe48fd4f92008-08-22 10:00:36 +02003065 /*
Jens Axboe48fd4f92008-08-22 10:00:36 +02003066 * Only clear out a write error when rewriting
Linus Torvalds1da177e2005-04-16 15:20:36 -07003067 */
Mike Christie2a222ca2016-06-05 14:31:43 -05003068 if (test_set_buffer_req(bh) && (op == REQ_OP_WRITE))
Linus Torvalds1da177e2005-04-16 15:20:36 -07003069 clear_buffer_write_io_error(bh);
3070
3071 /*
3072 * from here on down, it's all bio -- do the initial mapping,
3073 * submit_bio -> generic_make_request may further map this bio around
3074 */
3075 bio = bio_alloc(GFP_NOIO, 1);
3076
Tejun Heo2a814902015-05-28 14:50:51 -04003077 if (wbc) {
Tejun Heob16b1de2015-06-02 08:39:48 -06003078 wbc_init_bio(wbc, bio);
Tejun Heo2a814902015-05-28 14:50:51 -04003079 wbc_account_io(wbc, bh->b_page, bh->b_size);
3080 }
Tejun Heobafc0db2015-06-02 08:37:23 -06003081
Kent Overstreet4f024f32013-10-11 15:44:27 -07003082 bio->bi_iter.bi_sector = bh->b_blocknr * (bh->b_size >> 9);
Linus Torvalds1da177e2005-04-16 15:20:36 -07003083 bio->bi_bdev = bh->b_bdev;
Linus Torvalds1da177e2005-04-16 15:20:36 -07003084
Kent Overstreet6cf66b42014-12-22 12:48:42 +01003085 bio_add_page(bio, bh->b_page, bh->b_size, bh_offset(bh));
3086 BUG_ON(bio->bi_iter.bi_size != bh->b_size);
Linus Torvalds1da177e2005-04-16 15:20:36 -07003087
3088 bio->bi_end_io = end_bio_bh_io_sync;
3089 bio->bi_private = bh;
Darrick J. Wong7136851112013-04-29 15:07:25 -07003090 bio->bi_flags |= bio_flags;
Linus Torvalds1da177e2005-04-16 15:20:36 -07003091
Linus Torvalds57302e02012-12-04 08:25:11 -08003092 /* Take care of bh's that straddle the end of the device */
Mike Christie2a222ca2016-06-05 14:31:43 -05003093 guard_bio_eod(op, bio);
Linus Torvalds57302e02012-12-04 08:25:11 -08003094
Theodore Ts'o877f9622013-04-20 19:58:37 -04003095 if (buffer_meta(bh))
Mike Christie2a222ca2016-06-05 14:31:43 -05003096 op_flags |= REQ_META;
Theodore Ts'o877f9622013-04-20 19:58:37 -04003097 if (buffer_prio(bh))
Mike Christie2a222ca2016-06-05 14:31:43 -05003098 op_flags |= REQ_PRIO;
3099 bio_set_op_attrs(bio, op, op_flags);
Theodore Ts'o877f9622013-04-20 19:58:37 -04003100
Mike Christie4e49ea42016-06-05 14:31:41 -05003101 submit_bio(bio);
Julia Lawallf6454b02015-05-26 21:59:53 +02003102 return 0;
Linus Torvalds1da177e2005-04-16 15:20:36 -07003103}
Tejun Heobafc0db2015-06-02 08:37:23 -06003104
Mike Christie2a222ca2016-06-05 14:31:43 -05003105int _submit_bh(int op, int op_flags, struct buffer_head *bh,
3106 unsigned long bio_flags)
Tejun Heobafc0db2015-06-02 08:37:23 -06003107{
Mike Christie2a222ca2016-06-05 14:31:43 -05003108 return submit_bh_wbc(op, op_flags, bh, bio_flags, NULL);
Tejun Heobafc0db2015-06-02 08:37:23 -06003109}
Darrick J. Wong7136851112013-04-29 15:07:25 -07003110EXPORT_SYMBOL_GPL(_submit_bh);
3111
Mike Christie2a222ca2016-06-05 14:31:43 -05003112int submit_bh(int op, int op_flags, struct buffer_head *bh)
Darrick J. Wong7136851112013-04-29 15:07:25 -07003113{
Mike Christie2a222ca2016-06-05 14:31:43 -05003114 return submit_bh_wbc(op, op_flags, bh, 0, NULL);
Darrick J. Wong7136851112013-04-29 15:07:25 -07003115}
H Hartley Sweeten1fe72ea2009-09-22 16:43:51 -07003116EXPORT_SYMBOL(submit_bh);
Linus Torvalds1da177e2005-04-16 15:20:36 -07003117
3118/**
3119 * ll_rw_block: low-level access to block devices (DEPRECATED)
Mike Christiedfec8a12016-06-05 14:31:44 -05003120 * @op: whether to %READ or %WRITE
Christoph Hellwig70246282016-07-19 11:28:41 +02003121 * @op_flags: rq_flag_bits
Linus Torvalds1da177e2005-04-16 15:20:36 -07003122 * @nr: number of &struct buffer_heads in the array
3123 * @bhs: array of pointers to &struct buffer_head
3124 *
Jan Karaa7662232005-09-06 15:19:10 -07003125 * ll_rw_block() takes an array of pointers to &struct buffer_heads, and
Christoph Hellwig70246282016-07-19 11:28:41 +02003126 * requests an I/O operation on them, either a %REQ_OP_READ or a %REQ_OP_WRITE.
3127 * @op_flags contains flags modifying the detailed I/O behavior, most notably
3128 * %REQ_RAHEAD.
Linus Torvalds1da177e2005-04-16 15:20:36 -07003129 *
3130 * This function drops any buffer that it cannot get a lock on (with the
Christoph Hellwig9cb569d2010-08-11 17:06:24 +02003131 * BH_Lock state bit), any buffer that appears to be clean when doing a write
3132 * request, and any buffer that appears to be up-to-date when doing read
3133 * request. Further it marks as clean buffers that are processed for
3134 * writing (the buffer cache won't assume that they are actually clean
3135 * until the buffer gets unlocked).
Linus Torvalds1da177e2005-04-16 15:20:36 -07003136 *
3137 * ll_rw_block sets b_end_io to simple completion handler that marks
Masanari Iidae2278672014-02-18 22:54:36 +09003138 * the buffer up-to-date (if appropriate), unlocks the buffer and wakes
Linus Torvalds1da177e2005-04-16 15:20:36 -07003139 * any waiters.
3140 *
3141 * All of the buffers must be for the same device, and must also be a
3142 * multiple of the current approved size for the device.
3143 */
Mike Christiedfec8a12016-06-05 14:31:44 -05003144void ll_rw_block(int op, int op_flags, int nr, struct buffer_head *bhs[])
Linus Torvalds1da177e2005-04-16 15:20:36 -07003145{
3146 int i;
3147
3148 for (i = 0; i < nr; i++) {
3149 struct buffer_head *bh = bhs[i];
3150
Christoph Hellwig9cb569d2010-08-11 17:06:24 +02003151 if (!trylock_buffer(bh))
Linus Torvalds1da177e2005-04-16 15:20:36 -07003152 continue;
Mike Christiedfec8a12016-06-05 14:31:44 -05003153 if (op == WRITE) {
Linus Torvalds1da177e2005-04-16 15:20:36 -07003154 if (test_clear_buffer_dirty(bh)) {
akpm@osdl.org76c30732005-04-16 15:24:07 -07003155 bh->b_end_io = end_buffer_write_sync;
OGAWA Hirofumie60e5c52006-02-03 03:04:43 -08003156 get_bh(bh);
Mike Christiedfec8a12016-06-05 14:31:44 -05003157 submit_bh(op, op_flags, bh);
Linus Torvalds1da177e2005-04-16 15:20:36 -07003158 continue;
3159 }
3160 } else {
Linus Torvalds1da177e2005-04-16 15:20:36 -07003161 if (!buffer_uptodate(bh)) {
akpm@osdl.org76c30732005-04-16 15:24:07 -07003162 bh->b_end_io = end_buffer_read_sync;
OGAWA Hirofumie60e5c52006-02-03 03:04:43 -08003163 get_bh(bh);
Mike Christiedfec8a12016-06-05 14:31:44 -05003164 submit_bh(op, op_flags, bh);
Linus Torvalds1da177e2005-04-16 15:20:36 -07003165 continue;
3166 }
3167 }
3168 unlock_buffer(bh);
Linus Torvalds1da177e2005-04-16 15:20:36 -07003169 }
3170}
H Hartley Sweeten1fe72ea2009-09-22 16:43:51 -07003171EXPORT_SYMBOL(ll_rw_block);
Linus Torvalds1da177e2005-04-16 15:20:36 -07003172
Mike Christie2a222ca2016-06-05 14:31:43 -05003173void write_dirty_buffer(struct buffer_head *bh, int op_flags)
Christoph Hellwig9cb569d2010-08-11 17:06:24 +02003174{
3175 lock_buffer(bh);
3176 if (!test_clear_buffer_dirty(bh)) {
3177 unlock_buffer(bh);
3178 return;
3179 }
3180 bh->b_end_io = end_buffer_write_sync;
3181 get_bh(bh);
Mike Christie2a222ca2016-06-05 14:31:43 -05003182 submit_bh(REQ_OP_WRITE, op_flags, bh);
Christoph Hellwig9cb569d2010-08-11 17:06:24 +02003183}
3184EXPORT_SYMBOL(write_dirty_buffer);
3185
Linus Torvalds1da177e2005-04-16 15:20:36 -07003186/*
3187 * For a data-integrity writeout, we need to wait upon any in-progress I/O
3188 * and then start new I/O and then wait upon it. The caller must have a ref on
3189 * the buffer_head.
3190 */
Mike Christie2a222ca2016-06-05 14:31:43 -05003191int __sync_dirty_buffer(struct buffer_head *bh, int op_flags)
Linus Torvalds1da177e2005-04-16 15:20:36 -07003192{
3193 int ret = 0;
3194
3195 WARN_ON(atomic_read(&bh->b_count) < 1);
3196 lock_buffer(bh);
3197 if (test_clear_buffer_dirty(bh)) {
3198 get_bh(bh);
3199 bh->b_end_io = end_buffer_write_sync;
Mike Christie2a222ca2016-06-05 14:31:43 -05003200 ret = submit_bh(REQ_OP_WRITE, op_flags, bh);
Linus Torvalds1da177e2005-04-16 15:20:36 -07003201 wait_on_buffer(bh);
Linus Torvalds1da177e2005-04-16 15:20:36 -07003202 if (!ret && !buffer_uptodate(bh))
3203 ret = -EIO;
3204 } else {
3205 unlock_buffer(bh);
3206 }
3207 return ret;
3208}
Christoph Hellwig87e99512010-08-11 17:05:45 +02003209EXPORT_SYMBOL(__sync_dirty_buffer);
3210
3211int sync_dirty_buffer(struct buffer_head *bh)
3212{
3213 return __sync_dirty_buffer(bh, WRITE_SYNC);
3214}
H Hartley Sweeten1fe72ea2009-09-22 16:43:51 -07003215EXPORT_SYMBOL(sync_dirty_buffer);
Linus Torvalds1da177e2005-04-16 15:20:36 -07003216
3217/*
3218 * try_to_free_buffers() checks if all the buffers on this particular page
3219 * are unused, and releases them if so.
3220 *
3221 * Exclusion against try_to_free_buffers may be obtained by either
3222 * locking the page or by holding its mapping's private_lock.
3223 *
3224 * If the page is dirty but all the buffers are clean then we need to
3225 * be sure to mark the page clean as well. This is because the page
3226 * may be against a block device, and a later reattachment of buffers
3227 * to a dirty page will set *all* buffers dirty. Which would corrupt
3228 * filesystem data on the same device.
3229 *
3230 * The same applies to regular filesystem pages: if all the buffers are
3231 * clean then we set the page clean and proceed. To do that, we require
3232 * total exclusion from __set_page_dirty_buffers(). That is obtained with
3233 * private_lock.
3234 *
3235 * try_to_free_buffers() is non-blocking.
3236 */
3237static inline int buffer_busy(struct buffer_head *bh)
3238{
3239 return atomic_read(&bh->b_count) |
3240 (bh->b_state & ((1 << BH_Dirty) | (1 << BH_Lock)));
3241}
3242
3243static int
3244drop_buffers(struct page *page, struct buffer_head **buffers_to_free)
3245{
3246 struct buffer_head *head = page_buffers(page);
3247 struct buffer_head *bh;
3248
3249 bh = head;
3250 do {
akpm@osdl.orgde7d5a32005-05-01 08:58:39 -07003251 if (buffer_write_io_error(bh) && page->mapping)
Michal Hocko5114a972016-10-11 13:56:01 -07003252 mapping_set_error(page->mapping, -EIO);
Linus Torvalds1da177e2005-04-16 15:20:36 -07003253 if (buffer_busy(bh))
3254 goto failed;
3255 bh = bh->b_this_page;
3256 } while (bh != head);
3257
3258 do {
3259 struct buffer_head *next = bh->b_this_page;
3260
Jan Kara535ee2f2008-02-08 04:21:59 -08003261 if (bh->b_assoc_map)
Linus Torvalds1da177e2005-04-16 15:20:36 -07003262 __remove_assoc_queue(bh);
3263 bh = next;
3264 } while (bh != head);
3265 *buffers_to_free = head;
3266 __clear_page_buffers(page);
3267 return 1;
3268failed:
3269 return 0;
3270}
3271
3272int try_to_free_buffers(struct page *page)
3273{
3274 struct address_space * const mapping = page->mapping;
3275 struct buffer_head *buffers_to_free = NULL;
3276 int ret = 0;
3277
3278 BUG_ON(!PageLocked(page));
Linus Torvaldsecdfc972007-01-26 12:47:06 -08003279 if (PageWriteback(page))
Linus Torvalds1da177e2005-04-16 15:20:36 -07003280 return 0;
3281
3282 if (mapping == NULL) { /* can this still happen? */
3283 ret = drop_buffers(page, &buffers_to_free);
3284 goto out;
3285 }
3286
3287 spin_lock(&mapping->private_lock);
3288 ret = drop_buffers(page, &buffers_to_free);
Linus Torvaldsecdfc972007-01-26 12:47:06 -08003289
3290 /*
3291 * If the filesystem writes its buffers by hand (eg ext3)
3292 * then we can have clean buffers against a dirty page. We
3293 * clean the page here; otherwise the VM will never notice
3294 * that the filesystem did any IO at all.
3295 *
3296 * Also, during truncate, discard_buffer will have marked all
3297 * the page's buffers clean. We discover that here and clean
3298 * the page also.
Nick Piggin87df7242007-01-30 14:36:27 +11003299 *
3300 * private_lock must be held over this entire operation in order
3301 * to synchronise against __set_page_dirty_buffers and prevent the
3302 * dirty bit from being lost.
Linus Torvaldsecdfc972007-01-26 12:47:06 -08003303 */
Tejun Heo11f81be2015-05-22 17:13:15 -04003304 if (ret)
3305 cancel_dirty_page(page);
Nick Piggin87df7242007-01-30 14:36:27 +11003306 spin_unlock(&mapping->private_lock);
Linus Torvalds1da177e2005-04-16 15:20:36 -07003307out:
3308 if (buffers_to_free) {
3309 struct buffer_head *bh = buffers_to_free;
3310
3311 do {
3312 struct buffer_head *next = bh->b_this_page;
3313 free_buffer_head(bh);
3314 bh = next;
3315 } while (bh != buffers_to_free);
3316 }
3317 return ret;
3318}
3319EXPORT_SYMBOL(try_to_free_buffers);
3320
Linus Torvalds1da177e2005-04-16 15:20:36 -07003321/*
3322 * There are no bdflush tunables left. But distributions are
3323 * still running obsolete flush daemons, so we terminate them here.
3324 *
3325 * Use of bdflush() is deprecated and will be removed in a future kernel.
Jens Axboe5b0830c2009-09-23 19:37:09 +02003326 * The `flush-X' kernel threads fully replace bdflush daemons and this call.
Linus Torvalds1da177e2005-04-16 15:20:36 -07003327 */
Heiko Carstensbdc480e2009-01-14 14:14:12 +01003328SYSCALL_DEFINE2(bdflush, int, func, long, data)
Linus Torvalds1da177e2005-04-16 15:20:36 -07003329{
3330 static int msg_count;
3331
3332 if (!capable(CAP_SYS_ADMIN))
3333 return -EPERM;
3334
3335 if (msg_count < 5) {
3336 msg_count++;
3337 printk(KERN_INFO
3338 "warning: process `%s' used the obsolete bdflush"
3339 " system call\n", current->comm);
3340 printk(KERN_INFO "Fix your initscripts?\n");
3341 }
3342
3343 if (func == 1)
3344 do_exit(0);
3345 return 0;
3346}
3347
3348/*
3349 * Buffer-head allocation
3350 */
Shai Fultheima0a9b042012-05-15 12:29:52 +03003351static struct kmem_cache *bh_cachep __read_mostly;
Linus Torvalds1da177e2005-04-16 15:20:36 -07003352
3353/*
3354 * Once the number of bh's in the machine exceeds this level, we start
3355 * stripping them in writeback.
3356 */
Zhang Yanfei43be5942013-02-22 16:35:46 -08003357static unsigned long max_buffer_heads;
Linus Torvalds1da177e2005-04-16 15:20:36 -07003358
3359int buffer_heads_over_limit;
3360
3361struct bh_accounting {
3362 int nr; /* Number of live bh's */
3363 int ratelimit; /* Limit cacheline bouncing */
3364};
3365
3366static DEFINE_PER_CPU(struct bh_accounting, bh_accounting) = {0, 0};
3367
3368static void recalc_bh_state(void)
3369{
3370 int i;
3371 int tot = 0;
3372
Christoph Lameteree1be862010-12-06 11:40:05 -06003373 if (__this_cpu_inc_return(bh_accounting.ratelimit) - 1 < 4096)
Linus Torvalds1da177e2005-04-16 15:20:36 -07003374 return;
Christoph Lameterc7b92512010-12-06 11:16:28 -06003375 __this_cpu_write(bh_accounting.ratelimit, 0);
Eric Dumazet8a143422006-03-24 03:18:10 -08003376 for_each_online_cpu(i)
Linus Torvalds1da177e2005-04-16 15:20:36 -07003377 tot += per_cpu(bh_accounting, i).nr;
3378 buffer_heads_over_limit = (tot > max_buffer_heads);
3379}
Christoph Lameterc7b92512010-12-06 11:16:28 -06003380
Al Virodd0fc662005-10-07 07:46:04 +01003381struct buffer_head *alloc_buffer_head(gfp_t gfp_flags)
Linus Torvalds1da177e2005-04-16 15:20:36 -07003382{
Richard Kennedy019b4d12010-03-10 15:20:33 -08003383 struct buffer_head *ret = kmem_cache_zalloc(bh_cachep, gfp_flags);
Linus Torvalds1da177e2005-04-16 15:20:36 -07003384 if (ret) {
Christoph Lametera35afb82007-05-16 22:10:57 -07003385 INIT_LIST_HEAD(&ret->b_assoc_buffers);
Christoph Lameterc7b92512010-12-06 11:16:28 -06003386 preempt_disable();
3387 __this_cpu_inc(bh_accounting.nr);
Linus Torvalds1da177e2005-04-16 15:20:36 -07003388 recalc_bh_state();
Christoph Lameterc7b92512010-12-06 11:16:28 -06003389 preempt_enable();
Linus Torvalds1da177e2005-04-16 15:20:36 -07003390 }
3391 return ret;
3392}
3393EXPORT_SYMBOL(alloc_buffer_head);
3394
3395void free_buffer_head(struct buffer_head *bh)
3396{
3397 BUG_ON(!list_empty(&bh->b_assoc_buffers));
3398 kmem_cache_free(bh_cachep, bh);
Christoph Lameterc7b92512010-12-06 11:16:28 -06003399 preempt_disable();
3400 __this_cpu_dec(bh_accounting.nr);
Linus Torvalds1da177e2005-04-16 15:20:36 -07003401 recalc_bh_state();
Christoph Lameterc7b92512010-12-06 11:16:28 -06003402 preempt_enable();
Linus Torvalds1da177e2005-04-16 15:20:36 -07003403}
3404EXPORT_SYMBOL(free_buffer_head);
3405
Linus Torvalds1da177e2005-04-16 15:20:36 -07003406static void buffer_exit_cpu(int cpu)
3407{
3408 int i;
3409 struct bh_lru *b = &per_cpu(bh_lrus, cpu);
3410
3411 for (i = 0; i < BH_LRU_SIZE; i++) {
3412 brelse(b->bhs[i]);
3413 b->bhs[i] = NULL;
3414 }
Christoph Lameterc7b92512010-12-06 11:16:28 -06003415 this_cpu_add(bh_accounting.nr, per_cpu(bh_accounting, cpu).nr);
Eric Dumazet8a143422006-03-24 03:18:10 -08003416 per_cpu(bh_accounting, cpu).nr = 0;
Linus Torvalds1da177e2005-04-16 15:20:36 -07003417}
3418
3419static int buffer_cpu_notify(struct notifier_block *self,
3420 unsigned long action, void *hcpu)
3421{
Rafael J. Wysocki8bb78442007-05-09 02:35:10 -07003422 if (action == CPU_DEAD || action == CPU_DEAD_FROZEN)
Linus Torvalds1da177e2005-04-16 15:20:36 -07003423 buffer_exit_cpu((unsigned long)hcpu);
3424 return NOTIFY_OK;
3425}
Linus Torvalds1da177e2005-04-16 15:20:36 -07003426
Aneesh Kumar K.V389d1b02008-01-28 23:58:26 -05003427/**
Randy Dunlapa6b91912008-03-19 17:01:00 -07003428 * bh_uptodate_or_lock - Test whether the buffer is uptodate
Aneesh Kumar K.V389d1b02008-01-28 23:58:26 -05003429 * @bh: struct buffer_head
3430 *
3431 * Return true if the buffer is up-to-date and false,
3432 * with the buffer locked, if not.
3433 */
3434int bh_uptodate_or_lock(struct buffer_head *bh)
3435{
3436 if (!buffer_uptodate(bh)) {
3437 lock_buffer(bh);
3438 if (!buffer_uptodate(bh))
3439 return 0;
3440 unlock_buffer(bh);
3441 }
3442 return 1;
3443}
3444EXPORT_SYMBOL(bh_uptodate_or_lock);
3445
3446/**
Randy Dunlapa6b91912008-03-19 17:01:00 -07003447 * bh_submit_read - Submit a locked buffer for reading
Aneesh Kumar K.V389d1b02008-01-28 23:58:26 -05003448 * @bh: struct buffer_head
3449 *
3450 * Returns zero on success and -EIO on error.
3451 */
3452int bh_submit_read(struct buffer_head *bh)
3453{
3454 BUG_ON(!buffer_locked(bh));
3455
3456 if (buffer_uptodate(bh)) {
3457 unlock_buffer(bh);
3458 return 0;
3459 }
3460
3461 get_bh(bh);
3462 bh->b_end_io = end_buffer_read_sync;
Mike Christie2a222ca2016-06-05 14:31:43 -05003463 submit_bh(REQ_OP_READ, 0, bh);
Aneesh Kumar K.V389d1b02008-01-28 23:58:26 -05003464 wait_on_buffer(bh);
3465 if (buffer_uptodate(bh))
3466 return 0;
3467 return -EIO;
3468}
3469EXPORT_SYMBOL(bh_submit_read);
3470
Linus Torvalds1da177e2005-04-16 15:20:36 -07003471void __init buffer_init(void)
3472{
Zhang Yanfei43be5942013-02-22 16:35:46 -08003473 unsigned long nrpages;
Linus Torvalds1da177e2005-04-16 15:20:36 -07003474
Christoph Lameterb98938c2008-02-04 22:28:36 -08003475 bh_cachep = kmem_cache_create("buffer_head",
3476 sizeof(struct buffer_head), 0,
3477 (SLAB_RECLAIM_ACCOUNT|SLAB_PANIC|
3478 SLAB_MEM_SPREAD),
Richard Kennedy019b4d12010-03-10 15:20:33 -08003479 NULL);
Linus Torvalds1da177e2005-04-16 15:20:36 -07003480
3481 /*
3482 * Limit the bh occupancy to 10% of ZONE_NORMAL
3483 */
3484 nrpages = (nr_free_buffer_pages() * 10) / 100;
3485 max_buffer_heads = nrpages * (PAGE_SIZE / sizeof(struct buffer_head));
3486 hotcpu_notifier(buffer_cpu_notify, 0);
3487}