Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1 | /* |
| 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 Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 21 | #include <linux/kernel.h> |
| 22 | #include <linux/syscalls.h> |
| 23 | #include <linux/fs.h> |
| 24 | #include <linux/mm.h> |
| 25 | #include <linux/percpu.h> |
| 26 | #include <linux/slab.h> |
| 27 | #include <linux/smp_lock.h> |
Randy Dunlap | 16f7e0f | 2006-01-11 12:17:46 -0800 | [diff] [blame] | 28 | #include <linux/capability.h> |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 29 | #include <linux/blkdev.h> |
| 30 | #include <linux/file.h> |
| 31 | #include <linux/quotaops.h> |
| 32 | #include <linux/highmem.h> |
| 33 | #include <linux/module.h> |
| 34 | #include <linux/writeback.h> |
| 35 | #include <linux/hash.h> |
| 36 | #include <linux/suspend.h> |
| 37 | #include <linux/buffer_head.h> |
Andrew Morton | 55e829a | 2006-12-10 02:19:27 -0800 | [diff] [blame] | 38 | #include <linux/task_io_accounting_ops.h> |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 39 | #include <linux/bio.h> |
| 40 | #include <linux/notifier.h> |
| 41 | #include <linux/cpu.h> |
| 42 | #include <linux/bitops.h> |
| 43 | #include <linux/mpage.h> |
Ingo Molnar | fb1c8f9 | 2005-09-10 00:25:56 -0700 | [diff] [blame] | 44 | #include <linux/bit_spinlock.h> |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 45 | |
| 46 | static int fsync_buffers_list(spinlock_t *lock, struct list_head *list); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 47 | |
| 48 | #define BH_ENTRY(list) list_entry((list), struct buffer_head, b_assoc_buffers) |
| 49 | |
| 50 | inline void |
| 51 | init_buffer(struct buffer_head *bh, bh_end_io_t *handler, void *private) |
| 52 | { |
| 53 | bh->b_end_io = handler; |
| 54 | bh->b_private = private; |
| 55 | } |
| 56 | |
| 57 | static int sync_buffer(void *word) |
| 58 | { |
| 59 | struct block_device *bd; |
| 60 | struct buffer_head *bh |
| 61 | = container_of(word, struct buffer_head, b_state); |
| 62 | |
| 63 | smp_mb(); |
| 64 | bd = bh->b_bdev; |
| 65 | if (bd) |
| 66 | blk_run_address_space(bd->bd_inode->i_mapping); |
| 67 | io_schedule(); |
| 68 | return 0; |
| 69 | } |
| 70 | |
| 71 | void fastcall __lock_buffer(struct buffer_head *bh) |
| 72 | { |
| 73 | wait_on_bit_lock(&bh->b_state, BH_Lock, sync_buffer, |
| 74 | TASK_UNINTERRUPTIBLE); |
| 75 | } |
| 76 | EXPORT_SYMBOL(__lock_buffer); |
| 77 | |
| 78 | void fastcall unlock_buffer(struct buffer_head *bh) |
| 79 | { |
Nick Piggin | 72ed3d0 | 2007-02-10 01:46:22 -0800 | [diff] [blame] | 80 | smp_mb__before_clear_bit(); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 81 | clear_buffer_locked(bh); |
| 82 | smp_mb__after_clear_bit(); |
| 83 | wake_up_bit(&bh->b_state, BH_Lock); |
| 84 | } |
| 85 | |
| 86 | /* |
| 87 | * Block until a buffer comes unlocked. This doesn't stop it |
| 88 | * from becoming locked again - you have to lock it yourself |
| 89 | * if you want to preserve its state. |
| 90 | */ |
| 91 | void __wait_on_buffer(struct buffer_head * bh) |
| 92 | { |
| 93 | wait_on_bit(&bh->b_state, BH_Lock, sync_buffer, TASK_UNINTERRUPTIBLE); |
| 94 | } |
| 95 | |
| 96 | static void |
| 97 | __clear_page_buffers(struct page *page) |
| 98 | { |
| 99 | ClearPagePrivate(page); |
Hugh Dickins | 4c21e2f | 2005-10-29 18:16:40 -0700 | [diff] [blame] | 100 | set_page_private(page, 0); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 101 | page_cache_release(page); |
| 102 | } |
| 103 | |
| 104 | static void buffer_io_error(struct buffer_head *bh) |
| 105 | { |
| 106 | char b[BDEVNAME_SIZE]; |
| 107 | |
| 108 | printk(KERN_ERR "Buffer I/O error on device %s, logical block %Lu\n", |
| 109 | bdevname(bh->b_bdev, b), |
| 110 | (unsigned long long)bh->b_blocknr); |
| 111 | } |
| 112 | |
| 113 | /* |
| 114 | * Default synchronous end-of-IO handler.. Just mark it up-to-date and |
| 115 | * unlock the buffer. This is what ll_rw_block uses too. |
| 116 | */ |
| 117 | void end_buffer_read_sync(struct buffer_head *bh, int uptodate) |
| 118 | { |
| 119 | if (uptodate) { |
| 120 | set_buffer_uptodate(bh); |
| 121 | } else { |
| 122 | /* This happens, due to failed READA attempts. */ |
| 123 | clear_buffer_uptodate(bh); |
| 124 | } |
| 125 | unlock_buffer(bh); |
| 126 | put_bh(bh); |
| 127 | } |
| 128 | |
| 129 | void end_buffer_write_sync(struct buffer_head *bh, int uptodate) |
| 130 | { |
| 131 | char b[BDEVNAME_SIZE]; |
| 132 | |
| 133 | if (uptodate) { |
| 134 | set_buffer_uptodate(bh); |
| 135 | } else { |
| 136 | if (!buffer_eopnotsupp(bh) && printk_ratelimit()) { |
| 137 | buffer_io_error(bh); |
| 138 | printk(KERN_WARNING "lost page write due to " |
| 139 | "I/O error on %s\n", |
| 140 | bdevname(bh->b_bdev, b)); |
| 141 | } |
| 142 | set_buffer_write_io_error(bh); |
| 143 | clear_buffer_uptodate(bh); |
| 144 | } |
| 145 | unlock_buffer(bh); |
| 146 | put_bh(bh); |
| 147 | } |
| 148 | |
| 149 | /* |
| 150 | * Write out and wait upon all the dirty data associated with a block |
| 151 | * device via its mapping. Does not take the superblock lock. |
| 152 | */ |
| 153 | int sync_blockdev(struct block_device *bdev) |
| 154 | { |
| 155 | int ret = 0; |
| 156 | |
OGAWA Hirofumi | 28fd129 | 2006-01-08 01:02:14 -0800 | [diff] [blame] | 157 | if (bdev) |
| 158 | ret = filemap_write_and_wait(bdev->bd_inode->i_mapping); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 159 | return ret; |
| 160 | } |
| 161 | EXPORT_SYMBOL(sync_blockdev); |
| 162 | |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 163 | /* |
| 164 | * Write out and wait upon all dirty data associated with this |
| 165 | * device. Filesystem data as well as the underlying block |
| 166 | * device. Takes the superblock lock. |
| 167 | */ |
| 168 | int fsync_bdev(struct block_device *bdev) |
| 169 | { |
| 170 | struct super_block *sb = get_super(bdev); |
| 171 | if (sb) { |
| 172 | int res = fsync_super(sb); |
| 173 | drop_super(sb); |
| 174 | return res; |
| 175 | } |
| 176 | return sync_blockdev(bdev); |
| 177 | } |
| 178 | |
| 179 | /** |
| 180 | * freeze_bdev -- lock a filesystem and force it into a consistent state |
| 181 | * @bdev: blockdevice to lock |
| 182 | * |
David Chinner | f73ca1b | 2007-01-10 23:15:41 -0800 | [diff] [blame] | 183 | * This takes the block device bd_mount_sem to make sure no new mounts |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 184 | * happen on bdev until thaw_bdev() is called. |
| 185 | * If a superblock is found on this device, we take the s_umount semaphore |
| 186 | * on it to make sure nobody unmounts until the snapshot creation is done. |
| 187 | */ |
| 188 | struct super_block *freeze_bdev(struct block_device *bdev) |
| 189 | { |
| 190 | struct super_block *sb; |
| 191 | |
David Chinner | f73ca1b | 2007-01-10 23:15:41 -0800 | [diff] [blame] | 192 | down(&bdev->bd_mount_sem); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 193 | sb = get_super(bdev); |
| 194 | if (sb && !(sb->s_flags & MS_RDONLY)) { |
| 195 | sb->s_frozen = SB_FREEZE_WRITE; |
akpm@osdl.org | d59dd46 | 2005-05-01 08:58:47 -0700 | [diff] [blame] | 196 | smp_wmb(); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 197 | |
OGAWA Hirofumi | d25b9a1 | 2006-03-25 03:07:44 -0800 | [diff] [blame] | 198 | __fsync_super(sb); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 199 | |
| 200 | sb->s_frozen = SB_FREEZE_TRANS; |
akpm@osdl.org | d59dd46 | 2005-05-01 08:58:47 -0700 | [diff] [blame] | 201 | smp_wmb(); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 202 | |
| 203 | sync_blockdev(sb->s_bdev); |
| 204 | |
| 205 | if (sb->s_op->write_super_lockfs) |
| 206 | sb->s_op->write_super_lockfs(sb); |
| 207 | } |
| 208 | |
| 209 | sync_blockdev(bdev); |
| 210 | return sb; /* thaw_bdev releases s->s_umount and bd_mount_sem */ |
| 211 | } |
| 212 | EXPORT_SYMBOL(freeze_bdev); |
| 213 | |
| 214 | /** |
| 215 | * thaw_bdev -- unlock filesystem |
| 216 | * @bdev: blockdevice to unlock |
| 217 | * @sb: associated superblock |
| 218 | * |
| 219 | * Unlocks the filesystem and marks it writeable again after freeze_bdev(). |
| 220 | */ |
| 221 | void thaw_bdev(struct block_device *bdev, struct super_block *sb) |
| 222 | { |
| 223 | if (sb) { |
| 224 | BUG_ON(sb->s_bdev != bdev); |
| 225 | |
| 226 | if (sb->s_op->unlockfs) |
| 227 | sb->s_op->unlockfs(sb); |
| 228 | sb->s_frozen = SB_UNFROZEN; |
akpm@osdl.org | d59dd46 | 2005-05-01 08:58:47 -0700 | [diff] [blame] | 229 | smp_wmb(); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 230 | wake_up(&sb->s_wait_unfrozen); |
| 231 | drop_super(sb); |
| 232 | } |
| 233 | |
David Chinner | f73ca1b | 2007-01-10 23:15:41 -0800 | [diff] [blame] | 234 | up(&bdev->bd_mount_sem); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 235 | } |
| 236 | EXPORT_SYMBOL(thaw_bdev); |
| 237 | |
| 238 | /* |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 239 | * Various filesystems appear to want __find_get_block to be non-blocking. |
| 240 | * But it's the page lock which protects the buffers. To get around this, |
| 241 | * we get exclusion from try_to_free_buffers with the blockdev mapping's |
| 242 | * private_lock. |
| 243 | * |
| 244 | * Hack idea: for the blockdev mapping, i_bufferlist_lock contention |
| 245 | * may be quite high. This code could TryLock the page, and if that |
| 246 | * succeeds, there is no need to take private_lock. (But if |
| 247 | * private_lock is contended then so is mapping->tree_lock). |
| 248 | */ |
| 249 | static struct buffer_head * |
Coywolf Qi Hunt | 385fd4c | 2005-11-07 00:59:39 -0800 | [diff] [blame] | 250 | __find_get_block_slow(struct block_device *bdev, sector_t block) |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 251 | { |
| 252 | struct inode *bd_inode = bdev->bd_inode; |
| 253 | struct address_space *bd_mapping = bd_inode->i_mapping; |
| 254 | struct buffer_head *ret = NULL; |
| 255 | pgoff_t index; |
| 256 | struct buffer_head *bh; |
| 257 | struct buffer_head *head; |
| 258 | struct page *page; |
| 259 | int all_mapped = 1; |
| 260 | |
| 261 | index = block >> (PAGE_CACHE_SHIFT - bd_inode->i_blkbits); |
| 262 | page = find_get_page(bd_mapping, index); |
| 263 | if (!page) |
| 264 | goto out; |
| 265 | |
| 266 | spin_lock(&bd_mapping->private_lock); |
| 267 | if (!page_has_buffers(page)) |
| 268 | goto out_unlock; |
| 269 | head = page_buffers(page); |
| 270 | bh = head; |
| 271 | do { |
| 272 | if (bh->b_blocknr == block) { |
| 273 | ret = bh; |
| 274 | get_bh(bh); |
| 275 | goto out_unlock; |
| 276 | } |
| 277 | if (!buffer_mapped(bh)) |
| 278 | all_mapped = 0; |
| 279 | bh = bh->b_this_page; |
| 280 | } while (bh != head); |
| 281 | |
| 282 | /* we might be here because some of the buffers on this page are |
| 283 | * not mapped. This is due to various races between |
| 284 | * file io on the block device and getblk. It gets dealt with |
| 285 | * elsewhere, don't buffer_error if we had some unmapped buffers |
| 286 | */ |
| 287 | if (all_mapped) { |
| 288 | printk("__find_get_block_slow() failed. " |
| 289 | "block=%llu, b_blocknr=%llu\n", |
Badari Pulavarty | 205f87f | 2006-03-26 01:38:00 -0800 | [diff] [blame] | 290 | (unsigned long long)block, |
| 291 | (unsigned long long)bh->b_blocknr); |
| 292 | printk("b_state=0x%08lx, b_size=%zu\n", |
| 293 | bh->b_state, bh->b_size); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 294 | printk("device blocksize: %d\n", 1 << bd_inode->i_blkbits); |
| 295 | } |
| 296 | out_unlock: |
| 297 | spin_unlock(&bd_mapping->private_lock); |
| 298 | page_cache_release(page); |
| 299 | out: |
| 300 | return ret; |
| 301 | } |
| 302 | |
| 303 | /* If invalidate_buffers() will trash dirty buffers, it means some kind |
| 304 | of fs corruption is going on. Trashing dirty data always imply losing |
| 305 | information that was supposed to be just stored on the physical layer |
| 306 | by the user. |
| 307 | |
| 308 | Thus invalidate_buffers in general usage is not allwowed to trash |
| 309 | dirty buffers. For example ioctl(FLSBLKBUF) expects dirty data to |
| 310 | be preserved. These buffers are simply skipped. |
| 311 | |
| 312 | We also skip buffers which are still in use. For example this can |
| 313 | happen if a userspace program is reading the block device. |
| 314 | |
| 315 | NOTE: In the case where the user removed a removable-media-disk even if |
| 316 | there's still dirty data not synced on disk (due a bug in the device driver |
| 317 | or due an error of the user), by not destroying the dirty buffers we could |
| 318 | generate corruption also on the next media inserted, thus a parameter is |
| 319 | necessary to handle this case in the most safe way possible (trying |
| 320 | to not corrupt also the new disk inserted with the data belonging to |
| 321 | the old now corrupted disk). Also for the ramdisk the natural thing |
| 322 | to do in order to release the ramdisk memory is to destroy dirty buffers. |
| 323 | |
| 324 | These are two special cases. Normal usage imply the device driver |
| 325 | to issue a sync on the device (without waiting I/O completion) and |
| 326 | then an invalidate_buffers call that doesn't trash dirty buffers. |
| 327 | |
| 328 | For handling cache coherency with the blkdev pagecache the 'update' case |
| 329 | is been introduced. It is needed to re-read from disk any pinned |
| 330 | buffer. NOTE: re-reading from disk is destructive so we can do it only |
| 331 | when we assume nobody is changing the buffercache under our I/O and when |
| 332 | we think the disk contains more recent information than the buffercache. |
| 333 | The update == 1 pass marks the buffers we need to update, the update == 2 |
| 334 | pass does the actual I/O. */ |
Peter Zijlstra | f98393a | 2007-05-06 14:49:54 -0700 | [diff] [blame] | 335 | void invalidate_bdev(struct block_device *bdev) |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 336 | { |
Andrew Morton | 0e1dfc6 | 2006-07-30 03:03:28 -0700 | [diff] [blame] | 337 | struct address_space *mapping = bdev->bd_inode->i_mapping; |
| 338 | |
| 339 | if (mapping->nrpages == 0) |
| 340 | return; |
| 341 | |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 342 | invalidate_bh_lrus(); |
Andrew Morton | fc0ecff | 2007-02-10 01:45:39 -0800 | [diff] [blame] | 343 | invalidate_mapping_pages(mapping, 0, -1); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 344 | } |
| 345 | |
| 346 | /* |
| 347 | * Kick pdflush then try to free up some ZONE_NORMAL memory. |
| 348 | */ |
| 349 | static void free_more_memory(void) |
| 350 | { |
| 351 | struct zone **zones; |
| 352 | pg_data_t *pgdat; |
| 353 | |
Pekka J Enberg | 687a21c | 2005-06-28 20:44:55 -0700 | [diff] [blame] | 354 | wakeup_pdflush(1024); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 355 | yield(); |
| 356 | |
KAMEZAWA Hiroyuki | ec936fc | 2006-03-27 01:15:59 -0800 | [diff] [blame] | 357 | for_each_online_pgdat(pgdat) { |
Al Viro | af4ca45 | 2005-10-21 02:55:38 -0400 | [diff] [blame] | 358 | zones = pgdat->node_zonelists[gfp_zone(GFP_NOFS)].zones; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 359 | if (*zones) |
Darren Hart | 1ad539b | 2005-06-21 17:14:53 -0700 | [diff] [blame] | 360 | try_to_free_pages(zones, GFP_NOFS); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 361 | } |
| 362 | } |
| 363 | |
| 364 | /* |
| 365 | * I/O completion handler for block_read_full_page() - pages |
| 366 | * which come unlocked at the end of I/O. |
| 367 | */ |
| 368 | static void end_buffer_async_read(struct buffer_head *bh, int uptodate) |
| 369 | { |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 370 | unsigned long flags; |
Nick Piggin | a397220 | 2005-07-07 17:56:56 -0700 | [diff] [blame] | 371 | struct buffer_head *first; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 372 | struct buffer_head *tmp; |
| 373 | struct page *page; |
| 374 | int page_uptodate = 1; |
| 375 | |
| 376 | BUG_ON(!buffer_async_read(bh)); |
| 377 | |
| 378 | page = bh->b_page; |
| 379 | if (uptodate) { |
| 380 | set_buffer_uptodate(bh); |
| 381 | } else { |
| 382 | clear_buffer_uptodate(bh); |
| 383 | if (printk_ratelimit()) |
| 384 | buffer_io_error(bh); |
| 385 | SetPageError(page); |
| 386 | } |
| 387 | |
| 388 | /* |
| 389 | * Be _very_ careful from here on. Bad things can happen if |
| 390 | * two buffer heads end IO at almost the same time and both |
| 391 | * decide that the page is now completely done. |
| 392 | */ |
Nick Piggin | a397220 | 2005-07-07 17:56:56 -0700 | [diff] [blame] | 393 | first = page_buffers(page); |
| 394 | local_irq_save(flags); |
| 395 | bit_spin_lock(BH_Uptodate_Lock, &first->b_state); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 396 | clear_buffer_async_read(bh); |
| 397 | unlock_buffer(bh); |
| 398 | tmp = bh; |
| 399 | do { |
| 400 | if (!buffer_uptodate(tmp)) |
| 401 | page_uptodate = 0; |
| 402 | if (buffer_async_read(tmp)) { |
| 403 | BUG_ON(!buffer_locked(tmp)); |
| 404 | goto still_busy; |
| 405 | } |
| 406 | tmp = tmp->b_this_page; |
| 407 | } while (tmp != bh); |
Nick Piggin | a397220 | 2005-07-07 17:56:56 -0700 | [diff] [blame] | 408 | bit_spin_unlock(BH_Uptodate_Lock, &first->b_state); |
| 409 | local_irq_restore(flags); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 410 | |
| 411 | /* |
| 412 | * If none of the buffers had errors and they are all |
| 413 | * uptodate then we can set the page uptodate. |
| 414 | */ |
| 415 | if (page_uptodate && !PageError(page)) |
| 416 | SetPageUptodate(page); |
| 417 | unlock_page(page); |
| 418 | return; |
| 419 | |
| 420 | still_busy: |
Nick Piggin | a397220 | 2005-07-07 17:56:56 -0700 | [diff] [blame] | 421 | bit_spin_unlock(BH_Uptodate_Lock, &first->b_state); |
| 422 | local_irq_restore(flags); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 423 | return; |
| 424 | } |
| 425 | |
| 426 | /* |
| 427 | * Completion handler for block_write_full_page() - pages which are unlocked |
| 428 | * during I/O, and which have PageWriteback cleared upon I/O completion. |
| 429 | */ |
Adrian Bunk | b6cd0b7 | 2006-06-27 02:53:54 -0700 | [diff] [blame] | 430 | static void end_buffer_async_write(struct buffer_head *bh, int uptodate) |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 431 | { |
| 432 | char b[BDEVNAME_SIZE]; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 433 | unsigned long flags; |
Nick Piggin | a397220 | 2005-07-07 17:56:56 -0700 | [diff] [blame] | 434 | struct buffer_head *first; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 435 | struct buffer_head *tmp; |
| 436 | struct page *page; |
| 437 | |
| 438 | BUG_ON(!buffer_async_write(bh)); |
| 439 | |
| 440 | page = bh->b_page; |
| 441 | if (uptodate) { |
| 442 | set_buffer_uptodate(bh); |
| 443 | } else { |
| 444 | if (printk_ratelimit()) { |
| 445 | buffer_io_error(bh); |
| 446 | printk(KERN_WARNING "lost page write due to " |
| 447 | "I/O error on %s\n", |
| 448 | bdevname(bh->b_bdev, b)); |
| 449 | } |
| 450 | set_bit(AS_EIO, &page->mapping->flags); |
Jan Kara | 58ff407 | 2006-10-17 00:10:19 -0700 | [diff] [blame] | 451 | set_buffer_write_io_error(bh); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 452 | clear_buffer_uptodate(bh); |
| 453 | SetPageError(page); |
| 454 | } |
| 455 | |
Nick Piggin | a397220 | 2005-07-07 17:56:56 -0700 | [diff] [blame] | 456 | first = page_buffers(page); |
| 457 | local_irq_save(flags); |
| 458 | bit_spin_lock(BH_Uptodate_Lock, &first->b_state); |
| 459 | |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 460 | clear_buffer_async_write(bh); |
| 461 | unlock_buffer(bh); |
| 462 | tmp = bh->b_this_page; |
| 463 | while (tmp != bh) { |
| 464 | if (buffer_async_write(tmp)) { |
| 465 | BUG_ON(!buffer_locked(tmp)); |
| 466 | goto still_busy; |
| 467 | } |
| 468 | tmp = tmp->b_this_page; |
| 469 | } |
Nick Piggin | a397220 | 2005-07-07 17:56:56 -0700 | [diff] [blame] | 470 | bit_spin_unlock(BH_Uptodate_Lock, &first->b_state); |
| 471 | local_irq_restore(flags); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 472 | end_page_writeback(page); |
| 473 | return; |
| 474 | |
| 475 | still_busy: |
Nick Piggin | a397220 | 2005-07-07 17:56:56 -0700 | [diff] [blame] | 476 | bit_spin_unlock(BH_Uptodate_Lock, &first->b_state); |
| 477 | local_irq_restore(flags); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 478 | return; |
| 479 | } |
| 480 | |
| 481 | /* |
| 482 | * If a page's buffers are under async readin (end_buffer_async_read |
| 483 | * completion) then there is a possibility that another thread of |
| 484 | * control could lock one of the buffers after it has completed |
| 485 | * but while some of the other buffers have not completed. This |
| 486 | * locked buffer would confuse end_buffer_async_read() into not unlocking |
| 487 | * the page. So the absence of BH_Async_Read tells end_buffer_async_read() |
| 488 | * that this buffer is not under async I/O. |
| 489 | * |
| 490 | * The page comes unlocked when it has no locked buffer_async buffers |
| 491 | * left. |
| 492 | * |
| 493 | * PageLocked prevents anyone starting new async I/O reads any of |
| 494 | * the buffers. |
| 495 | * |
| 496 | * PageWriteback is used to prevent simultaneous writeout of the same |
| 497 | * page. |
| 498 | * |
| 499 | * PageLocked prevents anyone from starting writeback of a page which is |
| 500 | * under read I/O (PageWriteback is only ever set against a locked page). |
| 501 | */ |
| 502 | static void mark_buffer_async_read(struct buffer_head *bh) |
| 503 | { |
| 504 | bh->b_end_io = end_buffer_async_read; |
| 505 | set_buffer_async_read(bh); |
| 506 | } |
| 507 | |
| 508 | void mark_buffer_async_write(struct buffer_head *bh) |
| 509 | { |
| 510 | bh->b_end_io = end_buffer_async_write; |
| 511 | set_buffer_async_write(bh); |
| 512 | } |
| 513 | EXPORT_SYMBOL(mark_buffer_async_write); |
| 514 | |
| 515 | |
| 516 | /* |
| 517 | * fs/buffer.c contains helper functions for buffer-backed address space's |
| 518 | * fsync functions. A common requirement for buffer-based filesystems is |
| 519 | * that certain data from the backing blockdev needs to be written out for |
| 520 | * a successful fsync(). For example, ext2 indirect blocks need to be |
| 521 | * written back and waited upon before fsync() returns. |
| 522 | * |
| 523 | * The functions mark_buffer_inode_dirty(), fsync_inode_buffers(), |
| 524 | * inode_has_buffers() and invalidate_inode_buffers() are provided for the |
| 525 | * management of a list of dependent buffers at ->i_mapping->private_list. |
| 526 | * |
| 527 | * Locking is a little subtle: try_to_free_buffers() will remove buffers |
| 528 | * from their controlling inode's queue when they are being freed. But |
| 529 | * try_to_free_buffers() will be operating against the *blockdev* mapping |
| 530 | * at the time, not against the S_ISREG file which depends on those buffers. |
| 531 | * So the locking for private_list is via the private_lock in the address_space |
| 532 | * which backs the buffers. Which is different from the address_space |
| 533 | * against which the buffers are listed. So for a particular address_space, |
| 534 | * mapping->private_lock does *not* protect mapping->private_list! In fact, |
| 535 | * mapping->private_list will always be protected by the backing blockdev's |
| 536 | * ->private_lock. |
| 537 | * |
| 538 | * Which introduces a requirement: all buffers on an address_space's |
| 539 | * ->private_list must be from the same address_space: the blockdev's. |
| 540 | * |
| 541 | * address_spaces which do not place buffers at ->private_list via these |
| 542 | * utility functions are free to use private_lock and private_list for |
| 543 | * whatever they want. The only requirement is that list_empty(private_list) |
| 544 | * be true at clear_inode() time. |
| 545 | * |
| 546 | * FIXME: clear_inode should not call invalidate_inode_buffers(). The |
| 547 | * filesystems should do that. invalidate_inode_buffers() should just go |
| 548 | * BUG_ON(!list_empty). |
| 549 | * |
| 550 | * FIXME: mark_buffer_dirty_inode() is a data-plane operation. It should |
| 551 | * take an address_space, not an inode. And it should be called |
| 552 | * mark_buffer_dirty_fsync() to clearly define why those buffers are being |
| 553 | * queued up. |
| 554 | * |
| 555 | * FIXME: mark_buffer_dirty_inode() doesn't need to add the buffer to the |
| 556 | * list if it is already on a list. Because if the buffer is on a list, |
| 557 | * it *must* already be on the right one. If not, the filesystem is being |
| 558 | * silly. This will save a ton of locking. But first we have to ensure |
| 559 | * that buffers are taken *off* the old inode's list when they are freed |
| 560 | * (presumably in truncate). That requires careful auditing of all |
| 561 | * filesystems (do it inside bforget()). It could also be done by bringing |
| 562 | * b_inode back. |
| 563 | */ |
| 564 | |
| 565 | /* |
| 566 | * The buffer's backing address_space's private_lock must be held |
| 567 | */ |
| 568 | static inline void __remove_assoc_queue(struct buffer_head *bh) |
| 569 | { |
| 570 | list_del_init(&bh->b_assoc_buffers); |
Jan Kara | 58ff407 | 2006-10-17 00:10:19 -0700 | [diff] [blame] | 571 | WARN_ON(!bh->b_assoc_map); |
| 572 | if (buffer_write_io_error(bh)) |
| 573 | set_bit(AS_EIO, &bh->b_assoc_map->flags); |
| 574 | bh->b_assoc_map = NULL; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 575 | } |
| 576 | |
| 577 | int inode_has_buffers(struct inode *inode) |
| 578 | { |
| 579 | return !list_empty(&inode->i_data.private_list); |
| 580 | } |
| 581 | |
| 582 | /* |
| 583 | * osync is designed to support O_SYNC io. It waits synchronously for |
| 584 | * all already-submitted IO to complete, but does not queue any new |
| 585 | * writes to the disk. |
| 586 | * |
| 587 | * To do O_SYNC writes, just queue the buffer writes with ll_rw_block as |
| 588 | * you dirty the buffers, and then use osync_inode_buffers to wait for |
| 589 | * completion. Any other dirty buffers which are not yet queued for |
| 590 | * write will not be flushed to disk by the osync. |
| 591 | */ |
| 592 | static int osync_buffers_list(spinlock_t *lock, struct list_head *list) |
| 593 | { |
| 594 | struct buffer_head *bh; |
| 595 | struct list_head *p; |
| 596 | int err = 0; |
| 597 | |
| 598 | spin_lock(lock); |
| 599 | repeat: |
| 600 | list_for_each_prev(p, list) { |
| 601 | bh = BH_ENTRY(p); |
| 602 | if (buffer_locked(bh)) { |
| 603 | get_bh(bh); |
| 604 | spin_unlock(lock); |
| 605 | wait_on_buffer(bh); |
| 606 | if (!buffer_uptodate(bh)) |
| 607 | err = -EIO; |
| 608 | brelse(bh); |
| 609 | spin_lock(lock); |
| 610 | goto repeat; |
| 611 | } |
| 612 | } |
| 613 | spin_unlock(lock); |
| 614 | return err; |
| 615 | } |
| 616 | |
| 617 | /** |
| 618 | * sync_mapping_buffers - write out and wait upon a mapping's "associated" |
| 619 | * buffers |
Martin Waitz | 67be2dd | 2005-05-01 08:59:26 -0700 | [diff] [blame] | 620 | * @mapping: the mapping which wants those buffers written |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 621 | * |
| 622 | * Starts I/O against the buffers at mapping->private_list, and waits upon |
| 623 | * that I/O. |
| 624 | * |
Martin Waitz | 67be2dd | 2005-05-01 08:59:26 -0700 | [diff] [blame] | 625 | * Basically, this is a convenience function for fsync(). |
| 626 | * @mapping is a file or directory which needs those buffers to be written for |
| 627 | * a successful fsync(). |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 628 | */ |
| 629 | int sync_mapping_buffers(struct address_space *mapping) |
| 630 | { |
| 631 | struct address_space *buffer_mapping = mapping->assoc_mapping; |
| 632 | |
| 633 | if (buffer_mapping == NULL || list_empty(&mapping->private_list)) |
| 634 | return 0; |
| 635 | |
| 636 | return fsync_buffers_list(&buffer_mapping->private_lock, |
| 637 | &mapping->private_list); |
| 638 | } |
| 639 | EXPORT_SYMBOL(sync_mapping_buffers); |
| 640 | |
| 641 | /* |
| 642 | * Called when we've recently written block `bblock', and it is known that |
| 643 | * `bblock' was for a buffer_boundary() buffer. This means that the block at |
| 644 | * `bblock + 1' is probably a dirty indirect block. Hunt it down and, if it's |
| 645 | * dirty, schedule it for IO. So that indirects merge nicely with their data. |
| 646 | */ |
| 647 | void write_boundary_block(struct block_device *bdev, |
| 648 | sector_t bblock, unsigned blocksize) |
| 649 | { |
| 650 | struct buffer_head *bh = __find_get_block(bdev, bblock + 1, blocksize); |
| 651 | if (bh) { |
| 652 | if (buffer_dirty(bh)) |
| 653 | ll_rw_block(WRITE, 1, &bh); |
| 654 | put_bh(bh); |
| 655 | } |
| 656 | } |
| 657 | |
| 658 | void mark_buffer_dirty_inode(struct buffer_head *bh, struct inode *inode) |
| 659 | { |
| 660 | struct address_space *mapping = inode->i_mapping; |
| 661 | struct address_space *buffer_mapping = bh->b_page->mapping; |
| 662 | |
| 663 | mark_buffer_dirty(bh); |
| 664 | if (!mapping->assoc_mapping) { |
| 665 | mapping->assoc_mapping = buffer_mapping; |
| 666 | } else { |
Eric Sesterhenn | e827f92 | 2006-03-26 18:24:46 +0200 | [diff] [blame] | 667 | BUG_ON(mapping->assoc_mapping != buffer_mapping); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 668 | } |
| 669 | if (list_empty(&bh->b_assoc_buffers)) { |
| 670 | spin_lock(&buffer_mapping->private_lock); |
| 671 | list_move_tail(&bh->b_assoc_buffers, |
| 672 | &mapping->private_list); |
Jan Kara | 58ff407 | 2006-10-17 00:10:19 -0700 | [diff] [blame] | 673 | bh->b_assoc_map = mapping; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 674 | spin_unlock(&buffer_mapping->private_lock); |
| 675 | } |
| 676 | } |
| 677 | EXPORT_SYMBOL(mark_buffer_dirty_inode); |
| 678 | |
| 679 | /* |
| 680 | * Add a page to the dirty page list. |
| 681 | * |
| 682 | * It is a sad fact of life that this function is called from several places |
| 683 | * deeply under spinlocking. It may not sleep. |
| 684 | * |
| 685 | * If the page has buffers, the uptodate buffers are set dirty, to preserve |
| 686 | * dirty-state coherency between the page and the buffers. It the page does |
| 687 | * not have buffers then when they are later attached they will all be set |
| 688 | * dirty. |
| 689 | * |
| 690 | * The buffers are dirtied before the page is dirtied. There's a small race |
| 691 | * window in which a writepage caller may see the page cleanness but not the |
| 692 | * buffer dirtiness. That's fine. If this code were to set the page dirty |
| 693 | * before the buffers, a concurrent writepage caller could clear the page dirty |
| 694 | * bit, see a bunch of clean buffers and we'd end up with dirty buffers/clean |
| 695 | * page on the dirty page list. |
| 696 | * |
| 697 | * We use private_lock to lock against try_to_free_buffers while using the |
| 698 | * page's buffer list. Also use this to protect against clean buffers being |
| 699 | * added to the page after it was set dirty. |
| 700 | * |
| 701 | * FIXME: may need to call ->reservepage here as well. That's rather up to the |
| 702 | * address_space though. |
| 703 | */ |
| 704 | int __set_page_dirty_buffers(struct page *page) |
| 705 | { |
Nick Piggin | ebf7a22 | 2006-10-10 04:36:54 +0200 | [diff] [blame] | 706 | struct address_space * const mapping = page_mapping(page); |
| 707 | |
| 708 | if (unlikely(!mapping)) |
| 709 | return !TestSetPageDirty(page); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 710 | |
| 711 | spin_lock(&mapping->private_lock); |
| 712 | if (page_has_buffers(page)) { |
| 713 | struct buffer_head *head = page_buffers(page); |
| 714 | struct buffer_head *bh = head; |
| 715 | |
| 716 | do { |
| 717 | set_buffer_dirty(bh); |
| 718 | bh = bh->b_this_page; |
| 719 | } while (bh != head); |
| 720 | } |
| 721 | spin_unlock(&mapping->private_lock); |
| 722 | |
Andrew Morton | 8c08540 | 2006-12-10 02:19:24 -0800 | [diff] [blame] | 723 | if (TestSetPageDirty(page)) |
| 724 | return 0; |
| 725 | |
| 726 | write_lock_irq(&mapping->tree_lock); |
| 727 | if (page->mapping) { /* Race with truncate? */ |
Andrew Morton | 55e829a | 2006-12-10 02:19:27 -0800 | [diff] [blame] | 728 | if (mapping_cap_account_dirty(mapping)) { |
Andrew Morton | 8c08540 | 2006-12-10 02:19:24 -0800 | [diff] [blame] | 729 | __inc_zone_page_state(page, NR_FILE_DIRTY); |
Andrew Morton | 55e829a | 2006-12-10 02:19:27 -0800 | [diff] [blame] | 730 | task_io_account_write(PAGE_CACHE_SIZE); |
| 731 | } |
Andrew Morton | 8c08540 | 2006-12-10 02:19:24 -0800 | [diff] [blame] | 732 | radix_tree_tag_set(&mapping->page_tree, |
| 733 | page_index(page), PAGECACHE_TAG_DIRTY); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 734 | } |
Andrew Morton | 8c08540 | 2006-12-10 02:19:24 -0800 | [diff] [blame] | 735 | write_unlock_irq(&mapping->tree_lock); |
| 736 | __mark_inode_dirty(mapping->host, I_DIRTY_PAGES); |
| 737 | return 1; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 738 | } |
| 739 | EXPORT_SYMBOL(__set_page_dirty_buffers); |
| 740 | |
| 741 | /* |
| 742 | * Write out and wait upon a list of buffers. |
| 743 | * |
| 744 | * We have conflicting pressures: we want to make sure that all |
| 745 | * initially dirty buffers get waited on, but that any subsequently |
| 746 | * dirtied buffers don't. After all, we don't want fsync to last |
| 747 | * forever if somebody is actively writing to the file. |
| 748 | * |
| 749 | * Do this in two main stages: first we copy dirty buffers to a |
| 750 | * temporary inode list, queueing the writes as we go. Then we clean |
| 751 | * up, waiting for those writes to complete. |
| 752 | * |
| 753 | * During this second stage, any subsequent updates to the file may end |
| 754 | * up refiling the buffer on the original inode's dirty list again, so |
| 755 | * there is a chance we will end up with a buffer queued for write but |
| 756 | * not yet completed on that list. So, as a final cleanup we go through |
| 757 | * the osync code to catch these locked, dirty buffers without requeuing |
| 758 | * any newly dirty buffers for write. |
| 759 | */ |
| 760 | static int fsync_buffers_list(spinlock_t *lock, struct list_head *list) |
| 761 | { |
| 762 | struct buffer_head *bh; |
| 763 | struct list_head tmp; |
| 764 | int err = 0, err2; |
| 765 | |
| 766 | INIT_LIST_HEAD(&tmp); |
| 767 | |
| 768 | spin_lock(lock); |
| 769 | while (!list_empty(list)) { |
| 770 | bh = BH_ENTRY(list->next); |
Jan Kara | 58ff407 | 2006-10-17 00:10:19 -0700 | [diff] [blame] | 771 | __remove_assoc_queue(bh); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 772 | if (buffer_dirty(bh) || buffer_locked(bh)) { |
| 773 | list_add(&bh->b_assoc_buffers, &tmp); |
| 774 | if (buffer_dirty(bh)) { |
| 775 | get_bh(bh); |
| 776 | spin_unlock(lock); |
| 777 | /* |
| 778 | * Ensure any pending I/O completes so that |
| 779 | * ll_rw_block() actually writes the current |
| 780 | * contents - it is a noop if I/O is still in |
| 781 | * flight on potentially older contents. |
| 782 | */ |
Jan Kara | a766223 | 2005-09-06 15:19:10 -0700 | [diff] [blame] | 783 | ll_rw_block(SWRITE, 1, &bh); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 784 | brelse(bh); |
| 785 | spin_lock(lock); |
| 786 | } |
| 787 | } |
| 788 | } |
| 789 | |
| 790 | while (!list_empty(&tmp)) { |
| 791 | bh = BH_ENTRY(tmp.prev); |
Jan Kara | 58ff407 | 2006-10-17 00:10:19 -0700 | [diff] [blame] | 792 | list_del_init(&bh->b_assoc_buffers); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 793 | get_bh(bh); |
| 794 | spin_unlock(lock); |
| 795 | wait_on_buffer(bh); |
| 796 | if (!buffer_uptodate(bh)) |
| 797 | err = -EIO; |
| 798 | brelse(bh); |
| 799 | spin_lock(lock); |
| 800 | } |
| 801 | |
| 802 | spin_unlock(lock); |
| 803 | err2 = osync_buffers_list(lock, list); |
| 804 | if (err) |
| 805 | return err; |
| 806 | else |
| 807 | return err2; |
| 808 | } |
| 809 | |
| 810 | /* |
| 811 | * Invalidate any and all dirty buffers on a given inode. We are |
| 812 | * probably unmounting the fs, but that doesn't mean we have already |
| 813 | * done a sync(). Just drop the buffers from the inode list. |
| 814 | * |
| 815 | * NOTE: we take the inode's blockdev's mapping's private_lock. Which |
| 816 | * assumes that all the buffers are against the blockdev. Not true |
| 817 | * for reiserfs. |
| 818 | */ |
| 819 | void invalidate_inode_buffers(struct inode *inode) |
| 820 | { |
| 821 | if (inode_has_buffers(inode)) { |
| 822 | struct address_space *mapping = &inode->i_data; |
| 823 | struct list_head *list = &mapping->private_list; |
| 824 | struct address_space *buffer_mapping = mapping->assoc_mapping; |
| 825 | |
| 826 | spin_lock(&buffer_mapping->private_lock); |
| 827 | while (!list_empty(list)) |
| 828 | __remove_assoc_queue(BH_ENTRY(list->next)); |
| 829 | spin_unlock(&buffer_mapping->private_lock); |
| 830 | } |
| 831 | } |
| 832 | |
| 833 | /* |
| 834 | * Remove any clean buffers from the inode's buffer list. This is called |
| 835 | * when we're trying to free the inode itself. Those buffers can pin it. |
| 836 | * |
| 837 | * Returns true if all buffers were removed. |
| 838 | */ |
| 839 | int remove_inode_buffers(struct inode *inode) |
| 840 | { |
| 841 | int ret = 1; |
| 842 | |
| 843 | if (inode_has_buffers(inode)) { |
| 844 | struct address_space *mapping = &inode->i_data; |
| 845 | struct list_head *list = &mapping->private_list; |
| 846 | struct address_space *buffer_mapping = mapping->assoc_mapping; |
| 847 | |
| 848 | spin_lock(&buffer_mapping->private_lock); |
| 849 | while (!list_empty(list)) { |
| 850 | struct buffer_head *bh = BH_ENTRY(list->next); |
| 851 | if (buffer_dirty(bh)) { |
| 852 | ret = 0; |
| 853 | break; |
| 854 | } |
| 855 | __remove_assoc_queue(bh); |
| 856 | } |
| 857 | spin_unlock(&buffer_mapping->private_lock); |
| 858 | } |
| 859 | return ret; |
| 860 | } |
| 861 | |
| 862 | /* |
| 863 | * Create the appropriate buffers when given a page for data area and |
| 864 | * the size of each buffer.. Use the bh->b_this_page linked list to |
| 865 | * follow the buffers created. Return NULL if unable to create more |
| 866 | * buffers. |
| 867 | * |
| 868 | * The retry flag is used to differentiate async IO (paging, swapping) |
| 869 | * which may not fail from ordinary buffer allocations. |
| 870 | */ |
| 871 | struct buffer_head *alloc_page_buffers(struct page *page, unsigned long size, |
| 872 | int retry) |
| 873 | { |
| 874 | struct buffer_head *bh, *head; |
| 875 | long offset; |
| 876 | |
| 877 | try_again: |
| 878 | head = NULL; |
| 879 | offset = PAGE_SIZE; |
| 880 | while ((offset -= size) >= 0) { |
| 881 | bh = alloc_buffer_head(GFP_NOFS); |
| 882 | if (!bh) |
| 883 | goto no_grow; |
| 884 | |
| 885 | bh->b_bdev = NULL; |
| 886 | bh->b_this_page = head; |
| 887 | bh->b_blocknr = -1; |
| 888 | head = bh; |
| 889 | |
| 890 | bh->b_state = 0; |
| 891 | atomic_set(&bh->b_count, 0); |
Chris Mason | fc5cd58 | 2006-02-01 03:06:48 -0800 | [diff] [blame] | 892 | bh->b_private = NULL; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 893 | bh->b_size = size; |
| 894 | |
| 895 | /* Link the buffer to its page */ |
| 896 | set_bh_page(bh, page, offset); |
| 897 | |
Nathan Scott | 01ffe33 | 2006-01-17 09:02:07 +1100 | [diff] [blame] | 898 | init_buffer(bh, NULL, NULL); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 899 | } |
| 900 | return head; |
| 901 | /* |
| 902 | * In case anything failed, we just free everything we got. |
| 903 | */ |
| 904 | no_grow: |
| 905 | if (head) { |
| 906 | do { |
| 907 | bh = head; |
| 908 | head = head->b_this_page; |
| 909 | free_buffer_head(bh); |
| 910 | } while (head); |
| 911 | } |
| 912 | |
| 913 | /* |
| 914 | * Return failure for non-async IO requests. Async IO requests |
| 915 | * are not allowed to fail, so we have to wait until buffer heads |
| 916 | * become available. But we don't want tasks sleeping with |
| 917 | * partially complete buffers, so all were released above. |
| 918 | */ |
| 919 | if (!retry) |
| 920 | return NULL; |
| 921 | |
| 922 | /* We're _really_ low on memory. Now we just |
| 923 | * wait for old buffer heads to become free due to |
| 924 | * finishing IO. Since this is an async request and |
| 925 | * the reserve list is empty, we're sure there are |
| 926 | * async buffer heads in use. |
| 927 | */ |
| 928 | free_more_memory(); |
| 929 | goto try_again; |
| 930 | } |
| 931 | EXPORT_SYMBOL_GPL(alloc_page_buffers); |
| 932 | |
| 933 | static inline void |
| 934 | link_dev_buffers(struct page *page, struct buffer_head *head) |
| 935 | { |
| 936 | struct buffer_head *bh, *tail; |
| 937 | |
| 938 | bh = head; |
| 939 | do { |
| 940 | tail = bh; |
| 941 | bh = bh->b_this_page; |
| 942 | } while (bh); |
| 943 | tail->b_this_page = head; |
| 944 | attach_page_buffers(page, head); |
| 945 | } |
| 946 | |
| 947 | /* |
| 948 | * Initialise the state of a blockdev page's buffers. |
| 949 | */ |
| 950 | static void |
| 951 | init_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); |
| 957 | |
| 958 | do { |
| 959 | if (!buffer_mapped(bh)) { |
| 960 | init_buffer(bh, NULL, NULL); |
| 961 | bh->b_bdev = bdev; |
| 962 | bh->b_blocknr = block; |
| 963 | if (uptodate) |
| 964 | set_buffer_uptodate(bh); |
| 965 | set_buffer_mapped(bh); |
| 966 | } |
| 967 | block++; |
| 968 | bh = bh->b_this_page; |
| 969 | } while (bh != head); |
| 970 | } |
| 971 | |
| 972 | /* |
| 973 | * Create the page-cache page that contains the requested block. |
| 974 | * |
| 975 | * This is user purely for blockdev mappings. |
| 976 | */ |
| 977 | static struct page * |
| 978 | grow_dev_page(struct block_device *bdev, sector_t block, |
| 979 | pgoff_t index, int size) |
| 980 | { |
| 981 | struct inode *inode = bdev->bd_inode; |
| 982 | struct page *page; |
| 983 | struct buffer_head *bh; |
| 984 | |
| 985 | page = find_or_create_page(inode->i_mapping, index, GFP_NOFS); |
| 986 | if (!page) |
| 987 | return NULL; |
| 988 | |
Eric Sesterhenn | e827f92 | 2006-03-26 18:24:46 +0200 | [diff] [blame] | 989 | BUG_ON(!PageLocked(page)); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 990 | |
| 991 | if (page_has_buffers(page)) { |
| 992 | bh = page_buffers(page); |
| 993 | if (bh->b_size == size) { |
| 994 | init_page_buffers(page, bdev, block, size); |
| 995 | return page; |
| 996 | } |
| 997 | if (!try_to_free_buffers(page)) |
| 998 | goto failed; |
| 999 | } |
| 1000 | |
| 1001 | /* |
| 1002 | * Allocate some buffers for this page |
| 1003 | */ |
| 1004 | bh = alloc_page_buffers(page, size, 0); |
| 1005 | if (!bh) |
| 1006 | goto failed; |
| 1007 | |
| 1008 | /* |
| 1009 | * Link the page to the buffers and initialise them. Take the |
| 1010 | * lock to be atomic wrt __find_get_block(), which does not |
| 1011 | * run under the page lock. |
| 1012 | */ |
| 1013 | spin_lock(&inode->i_mapping->private_lock); |
| 1014 | link_dev_buffers(page, bh); |
| 1015 | init_page_buffers(page, bdev, block, size); |
| 1016 | spin_unlock(&inode->i_mapping->private_lock); |
| 1017 | return page; |
| 1018 | |
| 1019 | failed: |
| 1020 | BUG(); |
| 1021 | unlock_page(page); |
| 1022 | page_cache_release(page); |
| 1023 | return NULL; |
| 1024 | } |
| 1025 | |
| 1026 | /* |
| 1027 | * Create buffers for the specified block device block's page. If |
| 1028 | * that page was dirty, the buffers are set dirty also. |
| 1029 | * |
| 1030 | * Except that's a bug. Attaching dirty buffers to a dirty |
| 1031 | * blockdev's page can result in filesystem corruption, because |
| 1032 | * some of those buffers may be aliases of filesystem data. |
| 1033 | * grow_dev_page() will go BUG() if this happens. |
| 1034 | */ |
Arjan van de Ven | 858119e | 2006-01-14 13:20:43 -0800 | [diff] [blame] | 1035 | static int |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1036 | grow_buffers(struct block_device *bdev, sector_t block, int size) |
| 1037 | { |
| 1038 | struct page *page; |
| 1039 | pgoff_t index; |
| 1040 | int sizebits; |
| 1041 | |
| 1042 | sizebits = -1; |
| 1043 | do { |
| 1044 | sizebits++; |
| 1045 | } while ((size << sizebits) < PAGE_SIZE); |
| 1046 | |
| 1047 | index = block >> sizebits; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1048 | |
Andrew Morton | e565793 | 2006-10-11 01:21:46 -0700 | [diff] [blame] | 1049 | /* |
| 1050 | * Check for a block which wants to lie outside our maximum possible |
| 1051 | * pagecache index. (this comparison is done using sector_t types). |
| 1052 | */ |
| 1053 | if (unlikely(index != block >> sizebits)) { |
| 1054 | char b[BDEVNAME_SIZE]; |
| 1055 | |
| 1056 | printk(KERN_ERR "%s: requested out-of-range block %llu for " |
| 1057 | "device %s\n", |
| 1058 | __FUNCTION__, (unsigned long long)block, |
| 1059 | bdevname(bdev, b)); |
| 1060 | return -EIO; |
| 1061 | } |
| 1062 | block = index << sizebits; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1063 | /* Create a page with the proper size buffers.. */ |
| 1064 | page = grow_dev_page(bdev, block, index, size); |
| 1065 | if (!page) |
| 1066 | return 0; |
| 1067 | unlock_page(page); |
| 1068 | page_cache_release(page); |
| 1069 | return 1; |
| 1070 | } |
| 1071 | |
Adrian Bunk | 75c96f8 | 2005-05-05 16:16:09 -0700 | [diff] [blame] | 1072 | static struct buffer_head * |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1073 | __getblk_slow(struct block_device *bdev, sector_t block, int size) |
| 1074 | { |
| 1075 | /* Size must be multiple of hard sectorsize */ |
| 1076 | if (unlikely(size & (bdev_hardsect_size(bdev)-1) || |
| 1077 | (size < 512 || size > PAGE_SIZE))) { |
| 1078 | printk(KERN_ERR "getblk(): invalid block size %d requested\n", |
| 1079 | size); |
| 1080 | printk(KERN_ERR "hardsect size: %d\n", |
| 1081 | bdev_hardsect_size(bdev)); |
| 1082 | |
| 1083 | dump_stack(); |
| 1084 | return NULL; |
| 1085 | } |
| 1086 | |
| 1087 | for (;;) { |
| 1088 | struct buffer_head * bh; |
Andrew Morton | e565793 | 2006-10-11 01:21:46 -0700 | [diff] [blame] | 1089 | int ret; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1090 | |
| 1091 | bh = __find_get_block(bdev, block, size); |
| 1092 | if (bh) |
| 1093 | return bh; |
| 1094 | |
Andrew Morton | e565793 | 2006-10-11 01:21:46 -0700 | [diff] [blame] | 1095 | ret = grow_buffers(bdev, block, size); |
| 1096 | if (ret < 0) |
| 1097 | return NULL; |
| 1098 | if (ret == 0) |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1099 | free_more_memory(); |
| 1100 | } |
| 1101 | } |
| 1102 | |
| 1103 | /* |
| 1104 | * The relationship between dirty buffers and dirty pages: |
| 1105 | * |
| 1106 | * Whenever a page has any dirty buffers, the page's dirty bit is set, and |
| 1107 | * the page is tagged dirty in its radix tree. |
| 1108 | * |
| 1109 | * At all times, the dirtiness of the buffers represents the dirtiness of |
| 1110 | * subsections of the page. If the page has buffers, the page dirty bit is |
| 1111 | * merely a hint about the true dirty state. |
| 1112 | * |
| 1113 | * When a page is set dirty in its entirety, all its buffers are marked dirty |
| 1114 | * (if the page has buffers). |
| 1115 | * |
| 1116 | * When a buffer is marked dirty, its page is dirtied, but the page's other |
| 1117 | * buffers are not. |
| 1118 | * |
| 1119 | * Also. When blockdev buffers are explicitly read with bread(), they |
| 1120 | * individually become uptodate. But their backing page remains not |
| 1121 | * uptodate - even if all of its buffers are uptodate. A subsequent |
| 1122 | * block_read_full_page() against that page will discover all the uptodate |
| 1123 | * buffers, will set the page uptodate and will perform no I/O. |
| 1124 | */ |
| 1125 | |
| 1126 | /** |
| 1127 | * mark_buffer_dirty - mark a buffer_head as needing writeout |
Martin Waitz | 67be2dd | 2005-05-01 08:59:26 -0700 | [diff] [blame] | 1128 | * @bh: the buffer_head to mark dirty |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1129 | * |
| 1130 | * mark_buffer_dirty() will set the dirty bit against the buffer, then set its |
| 1131 | * backing page dirty, then tag the page as dirty in its address_space's radix |
| 1132 | * tree and then attach the address_space's inode to its superblock's dirty |
| 1133 | * inode list. |
| 1134 | * |
| 1135 | * mark_buffer_dirty() is atomic. It takes bh->b_page->mapping->private_lock, |
| 1136 | * mapping->tree_lock and the global inode_lock. |
| 1137 | */ |
| 1138 | void fastcall mark_buffer_dirty(struct buffer_head *bh) |
| 1139 | { |
| 1140 | if (!buffer_dirty(bh) && !test_set_buffer_dirty(bh)) |
| 1141 | __set_page_dirty_nobuffers(bh->b_page); |
| 1142 | } |
| 1143 | |
| 1144 | /* |
| 1145 | * Decrement a buffer_head's reference count. If all buffers against a page |
| 1146 | * have zero reference count, are clean and unlocked, and if the page is clean |
| 1147 | * and unlocked then try_to_free_buffers() may strip the buffers from the page |
| 1148 | * in preparation for freeing it (sometimes, rarely, buffers are removed from |
| 1149 | * a page but it ends up not being freed, and buffers may later be reattached). |
| 1150 | */ |
| 1151 | void __brelse(struct buffer_head * buf) |
| 1152 | { |
| 1153 | if (atomic_read(&buf->b_count)) { |
| 1154 | put_bh(buf); |
| 1155 | return; |
| 1156 | } |
| 1157 | printk(KERN_ERR "VFS: brelse: Trying to free free buffer\n"); |
| 1158 | WARN_ON(1); |
| 1159 | } |
| 1160 | |
| 1161 | /* |
| 1162 | * bforget() is like brelse(), except it discards any |
| 1163 | * potentially dirty data. |
| 1164 | */ |
| 1165 | void __bforget(struct buffer_head *bh) |
| 1166 | { |
| 1167 | clear_buffer_dirty(bh); |
| 1168 | if (!list_empty(&bh->b_assoc_buffers)) { |
| 1169 | struct address_space *buffer_mapping = bh->b_page->mapping; |
| 1170 | |
| 1171 | spin_lock(&buffer_mapping->private_lock); |
| 1172 | list_del_init(&bh->b_assoc_buffers); |
Jan Kara | 58ff407 | 2006-10-17 00:10:19 -0700 | [diff] [blame] | 1173 | bh->b_assoc_map = NULL; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1174 | spin_unlock(&buffer_mapping->private_lock); |
| 1175 | } |
| 1176 | __brelse(bh); |
| 1177 | } |
| 1178 | |
| 1179 | static struct buffer_head *__bread_slow(struct buffer_head *bh) |
| 1180 | { |
| 1181 | lock_buffer(bh); |
| 1182 | if (buffer_uptodate(bh)) { |
| 1183 | unlock_buffer(bh); |
| 1184 | return bh; |
| 1185 | } else { |
| 1186 | get_bh(bh); |
| 1187 | bh->b_end_io = end_buffer_read_sync; |
| 1188 | submit_bh(READ, bh); |
| 1189 | wait_on_buffer(bh); |
| 1190 | if (buffer_uptodate(bh)) |
| 1191 | return bh; |
| 1192 | } |
| 1193 | brelse(bh); |
| 1194 | return NULL; |
| 1195 | } |
| 1196 | |
| 1197 | /* |
| 1198 | * Per-cpu buffer LRU implementation. To reduce the cost of __find_get_block(). |
| 1199 | * The bhs[] array is sorted - newest buffer is at bhs[0]. Buffers have their |
| 1200 | * refcount elevated by one when they're in an LRU. A buffer can only appear |
| 1201 | * once in a particular CPU's LRU. A single buffer can be present in multiple |
| 1202 | * CPU's LRUs at the same time. |
| 1203 | * |
| 1204 | * This is a transparent caching front-end to sb_bread(), sb_getblk() and |
| 1205 | * sb_find_get_block(). |
| 1206 | * |
| 1207 | * The LRUs themselves only need locking against invalidate_bh_lrus. We use |
| 1208 | * a local interrupt disable for that. |
| 1209 | */ |
| 1210 | |
| 1211 | #define BH_LRU_SIZE 8 |
| 1212 | |
| 1213 | struct bh_lru { |
| 1214 | struct buffer_head *bhs[BH_LRU_SIZE]; |
| 1215 | }; |
| 1216 | |
| 1217 | static DEFINE_PER_CPU(struct bh_lru, bh_lrus) = {{ NULL }}; |
| 1218 | |
| 1219 | #ifdef CONFIG_SMP |
| 1220 | #define bh_lru_lock() local_irq_disable() |
| 1221 | #define bh_lru_unlock() local_irq_enable() |
| 1222 | #else |
| 1223 | #define bh_lru_lock() preempt_disable() |
| 1224 | #define bh_lru_unlock() preempt_enable() |
| 1225 | #endif |
| 1226 | |
| 1227 | static inline void check_irqs_on(void) |
| 1228 | { |
| 1229 | #ifdef irqs_disabled |
| 1230 | BUG_ON(irqs_disabled()); |
| 1231 | #endif |
| 1232 | } |
| 1233 | |
| 1234 | /* |
| 1235 | * The LRU management algorithm is dopey-but-simple. Sorry. |
| 1236 | */ |
| 1237 | static void bh_lru_install(struct buffer_head *bh) |
| 1238 | { |
| 1239 | struct buffer_head *evictee = NULL; |
| 1240 | struct bh_lru *lru; |
| 1241 | |
| 1242 | check_irqs_on(); |
| 1243 | bh_lru_lock(); |
| 1244 | lru = &__get_cpu_var(bh_lrus); |
| 1245 | if (lru->bhs[0] != bh) { |
| 1246 | struct buffer_head *bhs[BH_LRU_SIZE]; |
| 1247 | int in; |
| 1248 | int out = 0; |
| 1249 | |
| 1250 | get_bh(bh); |
| 1251 | bhs[out++] = bh; |
| 1252 | for (in = 0; in < BH_LRU_SIZE; in++) { |
| 1253 | struct buffer_head *bh2 = lru->bhs[in]; |
| 1254 | |
| 1255 | if (bh2 == bh) { |
| 1256 | __brelse(bh2); |
| 1257 | } else { |
| 1258 | if (out >= BH_LRU_SIZE) { |
| 1259 | BUG_ON(evictee != NULL); |
| 1260 | evictee = bh2; |
| 1261 | } else { |
| 1262 | bhs[out++] = bh2; |
| 1263 | } |
| 1264 | } |
| 1265 | } |
| 1266 | while (out < BH_LRU_SIZE) |
| 1267 | bhs[out++] = NULL; |
| 1268 | memcpy(lru->bhs, bhs, sizeof(bhs)); |
| 1269 | } |
| 1270 | bh_lru_unlock(); |
| 1271 | |
| 1272 | if (evictee) |
| 1273 | __brelse(evictee); |
| 1274 | } |
| 1275 | |
| 1276 | /* |
| 1277 | * Look up the bh in this cpu's LRU. If it's there, move it to the head. |
| 1278 | */ |
Arjan van de Ven | 858119e | 2006-01-14 13:20:43 -0800 | [diff] [blame] | 1279 | static struct buffer_head * |
Tomasz Kvarsin | 3991d3b | 2007-02-12 00:52:14 -0800 | [diff] [blame] | 1280 | lookup_bh_lru(struct block_device *bdev, sector_t block, unsigned size) |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1281 | { |
| 1282 | struct buffer_head *ret = NULL; |
| 1283 | struct bh_lru *lru; |
Tomasz Kvarsin | 3991d3b | 2007-02-12 00:52:14 -0800 | [diff] [blame] | 1284 | unsigned int i; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1285 | |
| 1286 | check_irqs_on(); |
| 1287 | bh_lru_lock(); |
| 1288 | lru = &__get_cpu_var(bh_lrus); |
| 1289 | for (i = 0; i < BH_LRU_SIZE; i++) { |
| 1290 | struct buffer_head *bh = lru->bhs[i]; |
| 1291 | |
| 1292 | if (bh && bh->b_bdev == bdev && |
| 1293 | bh->b_blocknr == block && bh->b_size == size) { |
| 1294 | if (i) { |
| 1295 | while (i) { |
| 1296 | lru->bhs[i] = lru->bhs[i - 1]; |
| 1297 | i--; |
| 1298 | } |
| 1299 | lru->bhs[0] = bh; |
| 1300 | } |
| 1301 | get_bh(bh); |
| 1302 | ret = bh; |
| 1303 | break; |
| 1304 | } |
| 1305 | } |
| 1306 | bh_lru_unlock(); |
| 1307 | return ret; |
| 1308 | } |
| 1309 | |
| 1310 | /* |
| 1311 | * Perform a pagecache lookup for the matching buffer. If it's there, refresh |
| 1312 | * it in the LRU and mark it as accessed. If it is not present then return |
| 1313 | * NULL |
| 1314 | */ |
| 1315 | struct buffer_head * |
Tomasz Kvarsin | 3991d3b | 2007-02-12 00:52:14 -0800 | [diff] [blame] | 1316 | __find_get_block(struct block_device *bdev, sector_t block, unsigned size) |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1317 | { |
| 1318 | struct buffer_head *bh = lookup_bh_lru(bdev, block, size); |
| 1319 | |
| 1320 | if (bh == NULL) { |
Coywolf Qi Hunt | 385fd4c | 2005-11-07 00:59:39 -0800 | [diff] [blame] | 1321 | bh = __find_get_block_slow(bdev, block); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1322 | if (bh) |
| 1323 | bh_lru_install(bh); |
| 1324 | } |
| 1325 | if (bh) |
| 1326 | touch_buffer(bh); |
| 1327 | return bh; |
| 1328 | } |
| 1329 | EXPORT_SYMBOL(__find_get_block); |
| 1330 | |
| 1331 | /* |
| 1332 | * __getblk will locate (and, if necessary, create) the buffer_head |
| 1333 | * which corresponds to the passed block_device, block and size. The |
| 1334 | * returned buffer has its reference count incremented. |
| 1335 | * |
| 1336 | * __getblk() cannot fail - it just keeps trying. If you pass it an |
| 1337 | * illegal block number, __getblk() will happily return a buffer_head |
| 1338 | * which represents the non-existent block. Very weird. |
| 1339 | * |
| 1340 | * __getblk() will lock up the machine if grow_dev_page's try_to_free_buffers() |
| 1341 | * attempt is failing. FIXME, perhaps? |
| 1342 | */ |
| 1343 | struct buffer_head * |
Tomasz Kvarsin | 3991d3b | 2007-02-12 00:52:14 -0800 | [diff] [blame] | 1344 | __getblk(struct block_device *bdev, sector_t block, unsigned size) |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1345 | { |
| 1346 | struct buffer_head *bh = __find_get_block(bdev, block, size); |
| 1347 | |
| 1348 | might_sleep(); |
| 1349 | if (bh == NULL) |
| 1350 | bh = __getblk_slow(bdev, block, size); |
| 1351 | return bh; |
| 1352 | } |
| 1353 | EXPORT_SYMBOL(__getblk); |
| 1354 | |
| 1355 | /* |
| 1356 | * Do async read-ahead on a buffer.. |
| 1357 | */ |
Tomasz Kvarsin | 3991d3b | 2007-02-12 00:52:14 -0800 | [diff] [blame] | 1358 | void __breadahead(struct block_device *bdev, sector_t block, unsigned size) |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1359 | { |
| 1360 | struct buffer_head *bh = __getblk(bdev, block, size); |
Andrew Morton | a3e713b | 2005-10-30 15:03:15 -0800 | [diff] [blame] | 1361 | if (likely(bh)) { |
| 1362 | ll_rw_block(READA, 1, &bh); |
| 1363 | brelse(bh); |
| 1364 | } |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1365 | } |
| 1366 | EXPORT_SYMBOL(__breadahead); |
| 1367 | |
| 1368 | /** |
| 1369 | * __bread() - reads a specified block and returns the bh |
Martin Waitz | 67be2dd | 2005-05-01 08:59:26 -0700 | [diff] [blame] | 1370 | * @bdev: the block_device to read from |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1371 | * @block: number of block |
| 1372 | * @size: size (in bytes) to read |
| 1373 | * |
| 1374 | * Reads a specified block, and returns buffer head that contains it. |
| 1375 | * It returns NULL if the block was unreadable. |
| 1376 | */ |
| 1377 | struct buffer_head * |
Tomasz Kvarsin | 3991d3b | 2007-02-12 00:52:14 -0800 | [diff] [blame] | 1378 | __bread(struct block_device *bdev, sector_t block, unsigned size) |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1379 | { |
| 1380 | struct buffer_head *bh = __getblk(bdev, block, size); |
| 1381 | |
Andrew Morton | a3e713b | 2005-10-30 15:03:15 -0800 | [diff] [blame] | 1382 | if (likely(bh) && !buffer_uptodate(bh)) |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1383 | bh = __bread_slow(bh); |
| 1384 | return bh; |
| 1385 | } |
| 1386 | EXPORT_SYMBOL(__bread); |
| 1387 | |
| 1388 | /* |
| 1389 | * invalidate_bh_lrus() is called rarely - but not only at unmount. |
| 1390 | * This doesn't race because it runs in each cpu either in irq |
| 1391 | * or with preempt disabled. |
| 1392 | */ |
| 1393 | static void invalidate_bh_lru(void *arg) |
| 1394 | { |
| 1395 | struct bh_lru *b = &get_cpu_var(bh_lrus); |
| 1396 | int i; |
| 1397 | |
| 1398 | for (i = 0; i < BH_LRU_SIZE; i++) { |
| 1399 | brelse(b->bhs[i]); |
| 1400 | b->bhs[i] = NULL; |
| 1401 | } |
| 1402 | put_cpu_var(bh_lrus); |
| 1403 | } |
| 1404 | |
Peter Zijlstra | f9a1439 | 2007-05-06 14:49:55 -0700 | [diff] [blame] | 1405 | void invalidate_bh_lrus(void) |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1406 | { |
| 1407 | on_each_cpu(invalidate_bh_lru, NULL, 1, 1); |
| 1408 | } |
| 1409 | |
| 1410 | void set_bh_page(struct buffer_head *bh, |
| 1411 | struct page *page, unsigned long offset) |
| 1412 | { |
| 1413 | bh->b_page = page; |
Eric Sesterhenn | e827f92 | 2006-03-26 18:24:46 +0200 | [diff] [blame] | 1414 | BUG_ON(offset >= PAGE_SIZE); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1415 | if (PageHighMem(page)) |
| 1416 | /* |
| 1417 | * This catches illegal uses and preserves the offset: |
| 1418 | */ |
| 1419 | bh->b_data = (char *)(0 + offset); |
| 1420 | else |
| 1421 | bh->b_data = page_address(page) + offset; |
| 1422 | } |
| 1423 | EXPORT_SYMBOL(set_bh_page); |
| 1424 | |
| 1425 | /* |
| 1426 | * Called when truncating a buffer on a page completely. |
| 1427 | */ |
Arjan van de Ven | 858119e | 2006-01-14 13:20:43 -0800 | [diff] [blame] | 1428 | static void discard_buffer(struct buffer_head * bh) |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1429 | { |
| 1430 | lock_buffer(bh); |
| 1431 | clear_buffer_dirty(bh); |
| 1432 | bh->b_bdev = NULL; |
| 1433 | clear_buffer_mapped(bh); |
| 1434 | clear_buffer_req(bh); |
| 1435 | clear_buffer_new(bh); |
| 1436 | clear_buffer_delay(bh); |
David Chinner | 33a266d | 2007-02-12 00:51:41 -0800 | [diff] [blame] | 1437 | clear_buffer_unwritten(bh); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1438 | unlock_buffer(bh); |
| 1439 | } |
| 1440 | |
| 1441 | /** |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1442 | * block_invalidatepage - invalidate part of all of a buffer-backed page |
| 1443 | * |
| 1444 | * @page: the page which is affected |
| 1445 | * @offset: the index of the truncation point |
| 1446 | * |
| 1447 | * block_invalidatepage() is called when all or part of the page has become |
| 1448 | * invalidatedby a truncate operation. |
| 1449 | * |
| 1450 | * block_invalidatepage() does not have to release all buffers, but it must |
| 1451 | * ensure that no dirty buffer is left outside @offset and that no I/O |
| 1452 | * is underway against any of the blocks which are outside the truncation |
| 1453 | * point. Because the caller is about to free (and possibly reuse) those |
| 1454 | * blocks on-disk. |
| 1455 | */ |
NeilBrown | 2ff28e2 | 2006-03-26 01:37:18 -0800 | [diff] [blame] | 1456 | void block_invalidatepage(struct page *page, unsigned long offset) |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1457 | { |
| 1458 | struct buffer_head *head, *bh, *next; |
| 1459 | unsigned int curr_off = 0; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1460 | |
| 1461 | BUG_ON(!PageLocked(page)); |
| 1462 | if (!page_has_buffers(page)) |
| 1463 | goto out; |
| 1464 | |
| 1465 | head = page_buffers(page); |
| 1466 | bh = head; |
| 1467 | do { |
| 1468 | unsigned int next_off = curr_off + bh->b_size; |
| 1469 | next = bh->b_this_page; |
| 1470 | |
| 1471 | /* |
| 1472 | * is this block fully invalidated? |
| 1473 | */ |
| 1474 | if (offset <= curr_off) |
| 1475 | discard_buffer(bh); |
| 1476 | curr_off = next_off; |
| 1477 | bh = next; |
| 1478 | } while (bh != head); |
| 1479 | |
| 1480 | /* |
| 1481 | * We release buffers only if the entire page is being invalidated. |
| 1482 | * The get_block cached value has been unconditionally invalidated, |
| 1483 | * so real IO is not possible anymore. |
| 1484 | */ |
| 1485 | if (offset == 0) |
NeilBrown | 2ff28e2 | 2006-03-26 01:37:18 -0800 | [diff] [blame] | 1486 | try_to_release_page(page, 0); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1487 | out: |
NeilBrown | 2ff28e2 | 2006-03-26 01:37:18 -0800 | [diff] [blame] | 1488 | return; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1489 | } |
| 1490 | EXPORT_SYMBOL(block_invalidatepage); |
| 1491 | |
| 1492 | /* |
| 1493 | * We attach and possibly dirty the buffers atomically wrt |
| 1494 | * __set_page_dirty_buffers() via private_lock. try_to_free_buffers |
| 1495 | * is already excluded via the page lock. |
| 1496 | */ |
| 1497 | void create_empty_buffers(struct page *page, |
| 1498 | unsigned long blocksize, unsigned long b_state) |
| 1499 | { |
| 1500 | struct buffer_head *bh, *head, *tail; |
| 1501 | |
| 1502 | head = alloc_page_buffers(page, blocksize, 1); |
| 1503 | bh = head; |
| 1504 | do { |
| 1505 | bh->b_state |= b_state; |
| 1506 | tail = bh; |
| 1507 | bh = bh->b_this_page; |
| 1508 | } while (bh); |
| 1509 | tail->b_this_page = head; |
| 1510 | |
| 1511 | spin_lock(&page->mapping->private_lock); |
| 1512 | if (PageUptodate(page) || PageDirty(page)) { |
| 1513 | bh = head; |
| 1514 | do { |
| 1515 | if (PageDirty(page)) |
| 1516 | set_buffer_dirty(bh); |
| 1517 | if (PageUptodate(page)) |
| 1518 | set_buffer_uptodate(bh); |
| 1519 | bh = bh->b_this_page; |
| 1520 | } while (bh != head); |
| 1521 | } |
| 1522 | attach_page_buffers(page, head); |
| 1523 | spin_unlock(&page->mapping->private_lock); |
| 1524 | } |
| 1525 | EXPORT_SYMBOL(create_empty_buffers); |
| 1526 | |
| 1527 | /* |
| 1528 | * We are taking a block for data and we don't want any output from any |
| 1529 | * buffer-cache aliases starting from return from that function and |
| 1530 | * until the moment when something will explicitly mark the buffer |
| 1531 | * dirty (hopefully that will not happen until we will free that block ;-) |
| 1532 | * We don't even need to mark it not-uptodate - nobody can expect |
| 1533 | * anything from a newly allocated buffer anyway. We used to used |
| 1534 | * unmap_buffer() for such invalidation, but that was wrong. We definitely |
| 1535 | * don't want to mark the alias unmapped, for example - it would confuse |
| 1536 | * anyone who might pick it with bread() afterwards... |
| 1537 | * |
| 1538 | * Also.. Note that bforget() doesn't lock the buffer. So there can |
| 1539 | * be writeout I/O going on against recently-freed buffers. We don't |
| 1540 | * wait on that I/O in bforget() - it's more efficient to wait on the I/O |
| 1541 | * only if we really need to. That happens here. |
| 1542 | */ |
| 1543 | void unmap_underlying_metadata(struct block_device *bdev, sector_t block) |
| 1544 | { |
| 1545 | struct buffer_head *old_bh; |
| 1546 | |
| 1547 | might_sleep(); |
| 1548 | |
Coywolf Qi Hunt | 385fd4c | 2005-11-07 00:59:39 -0800 | [diff] [blame] | 1549 | old_bh = __find_get_block_slow(bdev, block); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1550 | if (old_bh) { |
| 1551 | clear_buffer_dirty(old_bh); |
| 1552 | wait_on_buffer(old_bh); |
| 1553 | clear_buffer_req(old_bh); |
| 1554 | __brelse(old_bh); |
| 1555 | } |
| 1556 | } |
| 1557 | EXPORT_SYMBOL(unmap_underlying_metadata); |
| 1558 | |
| 1559 | /* |
| 1560 | * NOTE! All mapped/uptodate combinations are valid: |
| 1561 | * |
| 1562 | * Mapped Uptodate Meaning |
| 1563 | * |
| 1564 | * No No "unknown" - must do get_block() |
| 1565 | * No Yes "hole" - zero-filled |
| 1566 | * Yes No "allocated" - allocated on disk, not read in |
| 1567 | * Yes Yes "valid" - allocated and up-to-date in memory. |
| 1568 | * |
| 1569 | * "Dirty" is valid only with the last case (mapped+uptodate). |
| 1570 | */ |
| 1571 | |
| 1572 | /* |
| 1573 | * While block_write_full_page is writing back the dirty buffers under |
| 1574 | * the page lock, whoever dirtied the buffers may decide to clean them |
| 1575 | * again at any time. We handle that by only looking at the buffer |
| 1576 | * state inside lock_buffer(). |
| 1577 | * |
| 1578 | * If block_write_full_page() is called for regular writeback |
| 1579 | * (wbc->sync_mode == WB_SYNC_NONE) then it will redirty a page which has a |
| 1580 | * locked buffer. This only can happen if someone has written the buffer |
| 1581 | * directly, with submit_bh(). At the address_space level PageWriteback |
| 1582 | * prevents this contention from occurring. |
| 1583 | */ |
| 1584 | static int __block_write_full_page(struct inode *inode, struct page *page, |
| 1585 | get_block_t *get_block, struct writeback_control *wbc) |
| 1586 | { |
| 1587 | int err; |
| 1588 | sector_t block; |
| 1589 | sector_t last_block; |
Andrew Morton | f0fbd5f | 2005-05-05 16:15:48 -0700 | [diff] [blame] | 1590 | struct buffer_head *bh, *head; |
Badari Pulavarty | b0cf232 | 2006-03-26 01:38:00 -0800 | [diff] [blame] | 1591 | const unsigned blocksize = 1 << inode->i_blkbits; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1592 | int nr_underway = 0; |
| 1593 | |
| 1594 | BUG_ON(!PageLocked(page)); |
| 1595 | |
| 1596 | last_block = (i_size_read(inode) - 1) >> inode->i_blkbits; |
| 1597 | |
| 1598 | if (!page_has_buffers(page)) { |
Badari Pulavarty | b0cf232 | 2006-03-26 01:38:00 -0800 | [diff] [blame] | 1599 | create_empty_buffers(page, blocksize, |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1600 | (1 << BH_Dirty)|(1 << BH_Uptodate)); |
| 1601 | } |
| 1602 | |
| 1603 | /* |
| 1604 | * Be very careful. We have no exclusion from __set_page_dirty_buffers |
| 1605 | * here, and the (potentially unmapped) buffers may become dirty at |
| 1606 | * any time. If a buffer becomes dirty here after we've inspected it |
| 1607 | * then we just miss that fact, and the page stays dirty. |
| 1608 | * |
| 1609 | * Buffers outside i_size may be dirtied by __set_page_dirty_buffers; |
| 1610 | * handle that here by just cleaning them. |
| 1611 | */ |
| 1612 | |
Andrew Morton | 54b21a7 | 2006-01-08 01:03:05 -0800 | [diff] [blame] | 1613 | block = (sector_t)page->index << (PAGE_CACHE_SHIFT - inode->i_blkbits); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1614 | head = page_buffers(page); |
| 1615 | bh = head; |
| 1616 | |
| 1617 | /* |
| 1618 | * Get all the dirty buffers mapped to disk addresses and |
| 1619 | * handle any aliases from the underlying blockdev's mapping. |
| 1620 | */ |
| 1621 | do { |
| 1622 | if (block > last_block) { |
| 1623 | /* |
| 1624 | * mapped buffers outside i_size will occur, because |
| 1625 | * this page can be outside i_size when there is a |
| 1626 | * truncate in progress. |
| 1627 | */ |
| 1628 | /* |
| 1629 | * The buffer was zeroed by block_write_full_page() |
| 1630 | */ |
| 1631 | clear_buffer_dirty(bh); |
| 1632 | set_buffer_uptodate(bh); |
| 1633 | } else if (!buffer_mapped(bh) && buffer_dirty(bh)) { |
Badari Pulavarty | b0cf232 | 2006-03-26 01:38:00 -0800 | [diff] [blame] | 1634 | WARN_ON(bh->b_size != blocksize); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1635 | err = get_block(inode, block, bh, 1); |
| 1636 | if (err) |
| 1637 | goto recover; |
| 1638 | if (buffer_new(bh)) { |
| 1639 | /* blockdev mappings never come here */ |
| 1640 | clear_buffer_new(bh); |
| 1641 | unmap_underlying_metadata(bh->b_bdev, |
| 1642 | bh->b_blocknr); |
| 1643 | } |
| 1644 | } |
| 1645 | bh = bh->b_this_page; |
| 1646 | block++; |
| 1647 | } while (bh != head); |
| 1648 | |
| 1649 | do { |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1650 | if (!buffer_mapped(bh)) |
| 1651 | continue; |
| 1652 | /* |
| 1653 | * If it's a fully non-blocking write attempt and we cannot |
| 1654 | * lock the buffer then redirty the page. Note that this can |
| 1655 | * potentially cause a busy-wait loop from pdflush and kswapd |
| 1656 | * activity, but those code paths have their own higher-level |
| 1657 | * throttling. |
| 1658 | */ |
| 1659 | if (wbc->sync_mode != WB_SYNC_NONE || !wbc->nonblocking) { |
| 1660 | lock_buffer(bh); |
| 1661 | } else if (test_set_buffer_locked(bh)) { |
| 1662 | redirty_page_for_writepage(wbc, page); |
| 1663 | continue; |
| 1664 | } |
| 1665 | if (test_clear_buffer_dirty(bh)) { |
| 1666 | mark_buffer_async_write(bh); |
| 1667 | } else { |
| 1668 | unlock_buffer(bh); |
| 1669 | } |
| 1670 | } while ((bh = bh->b_this_page) != head); |
| 1671 | |
| 1672 | /* |
| 1673 | * The page and its buffers are protected by PageWriteback(), so we can |
| 1674 | * drop the bh refcounts early. |
| 1675 | */ |
| 1676 | BUG_ON(PageWriteback(page)); |
| 1677 | set_page_writeback(page); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1678 | |
| 1679 | do { |
| 1680 | struct buffer_head *next = bh->b_this_page; |
| 1681 | if (buffer_async_write(bh)) { |
| 1682 | submit_bh(WRITE, bh); |
| 1683 | nr_underway++; |
| 1684 | } |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1685 | bh = next; |
| 1686 | } while (bh != head); |
Andrew Morton | 05937ba | 2005-05-05 16:15:47 -0700 | [diff] [blame] | 1687 | unlock_page(page); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1688 | |
| 1689 | err = 0; |
| 1690 | done: |
| 1691 | if (nr_underway == 0) { |
| 1692 | /* |
| 1693 | * The page was marked dirty, but the buffers were |
| 1694 | * clean. Someone wrote them back by hand with |
| 1695 | * ll_rw_block/submit_bh. A rare case. |
| 1696 | */ |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1697 | end_page_writeback(page); |
Nick Piggin | 3d67f2d | 2007-05-06 14:49:05 -0700 | [diff] [blame] | 1698 | |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1699 | /* |
| 1700 | * The page and buffer_heads can be released at any time from |
| 1701 | * here on. |
| 1702 | */ |
| 1703 | wbc->pages_skipped++; /* We didn't write this page */ |
| 1704 | } |
| 1705 | return err; |
| 1706 | |
| 1707 | recover: |
| 1708 | /* |
| 1709 | * ENOSPC, or some other error. We may already have added some |
| 1710 | * blocks to the file, so we need to write these out to avoid |
| 1711 | * exposing stale data. |
| 1712 | * The page is currently locked and not marked for writeback |
| 1713 | */ |
| 1714 | bh = head; |
| 1715 | /* Recovery: lock and submit the mapped buffers */ |
| 1716 | do { |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1717 | if (buffer_mapped(bh) && buffer_dirty(bh)) { |
| 1718 | lock_buffer(bh); |
| 1719 | mark_buffer_async_write(bh); |
| 1720 | } else { |
| 1721 | /* |
| 1722 | * The buffer may have been set dirty during |
| 1723 | * attachment to a dirty page. |
| 1724 | */ |
| 1725 | clear_buffer_dirty(bh); |
| 1726 | } |
| 1727 | } while ((bh = bh->b_this_page) != head); |
| 1728 | SetPageError(page); |
| 1729 | BUG_ON(PageWriteback(page)); |
Andrew Morton | 7e4c369 | 2007-05-08 00:23:27 -0700 | [diff] [blame^] | 1730 | mapping_set_error(page->mapping, err); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1731 | set_page_writeback(page); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1732 | do { |
| 1733 | struct buffer_head *next = bh->b_this_page; |
| 1734 | if (buffer_async_write(bh)) { |
| 1735 | clear_buffer_dirty(bh); |
| 1736 | submit_bh(WRITE, bh); |
| 1737 | nr_underway++; |
| 1738 | } |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1739 | bh = next; |
| 1740 | } while (bh != head); |
Nick Piggin | ffda9d3 | 2007-02-20 13:57:54 -0800 | [diff] [blame] | 1741 | unlock_page(page); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1742 | goto done; |
| 1743 | } |
| 1744 | |
| 1745 | static int __block_prepare_write(struct inode *inode, struct page *page, |
| 1746 | unsigned from, unsigned to, get_block_t *get_block) |
| 1747 | { |
| 1748 | unsigned block_start, block_end; |
| 1749 | sector_t block; |
| 1750 | int err = 0; |
| 1751 | unsigned blocksize, bbits; |
| 1752 | struct buffer_head *bh, *head, *wait[2], **wait_bh=wait; |
| 1753 | |
| 1754 | BUG_ON(!PageLocked(page)); |
| 1755 | BUG_ON(from > PAGE_CACHE_SIZE); |
| 1756 | BUG_ON(to > PAGE_CACHE_SIZE); |
| 1757 | BUG_ON(from > to); |
| 1758 | |
| 1759 | blocksize = 1 << inode->i_blkbits; |
| 1760 | if (!page_has_buffers(page)) |
| 1761 | create_empty_buffers(page, blocksize, 0); |
| 1762 | head = page_buffers(page); |
| 1763 | |
| 1764 | bbits = inode->i_blkbits; |
| 1765 | block = (sector_t)page->index << (PAGE_CACHE_SHIFT - bbits); |
| 1766 | |
| 1767 | for(bh = head, block_start = 0; bh != head || !block_start; |
| 1768 | block++, block_start=block_end, bh = bh->b_this_page) { |
| 1769 | block_end = block_start + blocksize; |
| 1770 | if (block_end <= from || block_start >= to) { |
| 1771 | if (PageUptodate(page)) { |
| 1772 | if (!buffer_uptodate(bh)) |
| 1773 | set_buffer_uptodate(bh); |
| 1774 | } |
| 1775 | continue; |
| 1776 | } |
| 1777 | if (buffer_new(bh)) |
| 1778 | clear_buffer_new(bh); |
| 1779 | if (!buffer_mapped(bh)) { |
Badari Pulavarty | b0cf232 | 2006-03-26 01:38:00 -0800 | [diff] [blame] | 1780 | WARN_ON(bh->b_size != blocksize); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1781 | err = get_block(inode, block, bh, 1); |
| 1782 | if (err) |
Nick Piggin | f3ddbdc | 2005-05-05 16:15:45 -0700 | [diff] [blame] | 1783 | break; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1784 | if (buffer_new(bh)) { |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1785 | unmap_underlying_metadata(bh->b_bdev, |
| 1786 | bh->b_blocknr); |
| 1787 | if (PageUptodate(page)) { |
| 1788 | set_buffer_uptodate(bh); |
| 1789 | continue; |
| 1790 | } |
| 1791 | if (block_end > to || block_start < from) { |
| 1792 | void *kaddr; |
| 1793 | |
| 1794 | kaddr = kmap_atomic(page, KM_USER0); |
| 1795 | if (block_end > to) |
| 1796 | memset(kaddr+to, 0, |
| 1797 | block_end-to); |
| 1798 | if (block_start < from) |
| 1799 | memset(kaddr+block_start, |
| 1800 | 0, from-block_start); |
| 1801 | flush_dcache_page(page); |
| 1802 | kunmap_atomic(kaddr, KM_USER0); |
| 1803 | } |
| 1804 | continue; |
| 1805 | } |
| 1806 | } |
| 1807 | if (PageUptodate(page)) { |
| 1808 | if (!buffer_uptodate(bh)) |
| 1809 | set_buffer_uptodate(bh); |
| 1810 | continue; |
| 1811 | } |
| 1812 | if (!buffer_uptodate(bh) && !buffer_delay(bh) && |
David Chinner | 33a266d | 2007-02-12 00:51:41 -0800 | [diff] [blame] | 1813 | !buffer_unwritten(bh) && |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1814 | (block_start < from || block_end > to)) { |
| 1815 | ll_rw_block(READ, 1, &bh); |
| 1816 | *wait_bh++=bh; |
| 1817 | } |
| 1818 | } |
| 1819 | /* |
| 1820 | * If we issued read requests - let them complete. |
| 1821 | */ |
| 1822 | while(wait_bh > wait) { |
| 1823 | wait_on_buffer(*--wait_bh); |
| 1824 | if (!buffer_uptodate(*wait_bh)) |
Nick Piggin | f3ddbdc | 2005-05-05 16:15:45 -0700 | [diff] [blame] | 1825 | err = -EIO; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1826 | } |
Anton Altaparmakov | 152becd | 2005-06-23 00:10:21 -0700 | [diff] [blame] | 1827 | if (!err) { |
| 1828 | bh = head; |
| 1829 | do { |
| 1830 | if (buffer_new(bh)) |
| 1831 | clear_buffer_new(bh); |
| 1832 | } while ((bh = bh->b_this_page) != head); |
| 1833 | return 0; |
| 1834 | } |
Nick Piggin | f3ddbdc | 2005-05-05 16:15:45 -0700 | [diff] [blame] | 1835 | /* Error case: */ |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1836 | /* |
| 1837 | * Zero out any newly allocated blocks to avoid exposing stale |
| 1838 | * data. If BH_New is set, we know that the block was newly |
| 1839 | * allocated in the above loop. |
| 1840 | */ |
| 1841 | bh = head; |
| 1842 | block_start = 0; |
| 1843 | do { |
| 1844 | block_end = block_start+blocksize; |
| 1845 | if (block_end <= from) |
| 1846 | goto next_bh; |
| 1847 | if (block_start >= to) |
| 1848 | break; |
| 1849 | if (buffer_new(bh)) { |
| 1850 | void *kaddr; |
| 1851 | |
| 1852 | clear_buffer_new(bh); |
| 1853 | kaddr = kmap_atomic(page, KM_USER0); |
| 1854 | memset(kaddr+block_start, 0, bh->b_size); |
Monakhov Dmitriy | 8c58165 | 2006-10-11 01:22:00 -0700 | [diff] [blame] | 1855 | flush_dcache_page(page); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1856 | kunmap_atomic(kaddr, KM_USER0); |
| 1857 | set_buffer_uptodate(bh); |
| 1858 | mark_buffer_dirty(bh); |
| 1859 | } |
| 1860 | next_bh: |
| 1861 | block_start = block_end; |
| 1862 | bh = bh->b_this_page; |
| 1863 | } while (bh != head); |
| 1864 | return err; |
| 1865 | } |
| 1866 | |
| 1867 | static int __block_commit_write(struct inode *inode, struct page *page, |
| 1868 | unsigned from, unsigned to) |
| 1869 | { |
| 1870 | unsigned block_start, block_end; |
| 1871 | int partial = 0; |
| 1872 | unsigned blocksize; |
| 1873 | struct buffer_head *bh, *head; |
| 1874 | |
| 1875 | blocksize = 1 << inode->i_blkbits; |
| 1876 | |
| 1877 | for(bh = head = page_buffers(page), block_start = 0; |
| 1878 | bh != head || !block_start; |
| 1879 | block_start=block_end, bh = bh->b_this_page) { |
| 1880 | block_end = block_start + blocksize; |
| 1881 | if (block_end <= from || block_start >= to) { |
| 1882 | if (!buffer_uptodate(bh)) |
| 1883 | partial = 1; |
| 1884 | } else { |
| 1885 | set_buffer_uptodate(bh); |
| 1886 | mark_buffer_dirty(bh); |
| 1887 | } |
| 1888 | } |
| 1889 | |
| 1890 | /* |
| 1891 | * If this is a partial write which happened to make all buffers |
| 1892 | * uptodate then we can optimize away a bogus readpage() for |
| 1893 | * the next read(). Here we 'discover' whether the page went |
| 1894 | * uptodate as a result of this (potentially partial) write. |
| 1895 | */ |
| 1896 | if (!partial) |
| 1897 | SetPageUptodate(page); |
| 1898 | return 0; |
| 1899 | } |
| 1900 | |
| 1901 | /* |
| 1902 | * Generic "read page" function for block devices that have the normal |
| 1903 | * get_block functionality. This is most of the block device filesystems. |
| 1904 | * Reads the page asynchronously --- the unlock_buffer() and |
| 1905 | * set/clear_buffer_uptodate() functions propagate buffer state into the |
| 1906 | * page struct once IO has completed. |
| 1907 | */ |
| 1908 | int block_read_full_page(struct page *page, get_block_t *get_block) |
| 1909 | { |
| 1910 | struct inode *inode = page->mapping->host; |
| 1911 | sector_t iblock, lblock; |
| 1912 | struct buffer_head *bh, *head, *arr[MAX_BUF_PER_PAGE]; |
| 1913 | unsigned int blocksize; |
| 1914 | int nr, i; |
| 1915 | int fully_mapped = 1; |
| 1916 | |
Matt Mackall | cd7619d | 2005-05-01 08:59:01 -0700 | [diff] [blame] | 1917 | BUG_ON(!PageLocked(page)); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1918 | blocksize = 1 << inode->i_blkbits; |
| 1919 | if (!page_has_buffers(page)) |
| 1920 | create_empty_buffers(page, blocksize, 0); |
| 1921 | head = page_buffers(page); |
| 1922 | |
| 1923 | iblock = (sector_t)page->index << (PAGE_CACHE_SHIFT - inode->i_blkbits); |
| 1924 | lblock = (i_size_read(inode)+blocksize-1) >> inode->i_blkbits; |
| 1925 | bh = head; |
| 1926 | nr = 0; |
| 1927 | i = 0; |
| 1928 | |
| 1929 | do { |
| 1930 | if (buffer_uptodate(bh)) |
| 1931 | continue; |
| 1932 | |
| 1933 | if (!buffer_mapped(bh)) { |
Andrew Morton | c64610b | 2005-05-16 21:53:49 -0700 | [diff] [blame] | 1934 | int err = 0; |
| 1935 | |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1936 | fully_mapped = 0; |
| 1937 | if (iblock < lblock) { |
Badari Pulavarty | b0cf232 | 2006-03-26 01:38:00 -0800 | [diff] [blame] | 1938 | WARN_ON(bh->b_size != blocksize); |
Andrew Morton | c64610b | 2005-05-16 21:53:49 -0700 | [diff] [blame] | 1939 | err = get_block(inode, iblock, bh, 0); |
| 1940 | if (err) |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1941 | SetPageError(page); |
| 1942 | } |
| 1943 | if (!buffer_mapped(bh)) { |
| 1944 | void *kaddr = kmap_atomic(page, KM_USER0); |
| 1945 | memset(kaddr + i * blocksize, 0, blocksize); |
| 1946 | flush_dcache_page(page); |
| 1947 | kunmap_atomic(kaddr, KM_USER0); |
Andrew Morton | c64610b | 2005-05-16 21:53:49 -0700 | [diff] [blame] | 1948 | if (!err) |
| 1949 | set_buffer_uptodate(bh); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1950 | continue; |
| 1951 | } |
| 1952 | /* |
| 1953 | * get_block() might have updated the buffer |
| 1954 | * synchronously |
| 1955 | */ |
| 1956 | if (buffer_uptodate(bh)) |
| 1957 | continue; |
| 1958 | } |
| 1959 | arr[nr++] = bh; |
| 1960 | } while (i++, iblock++, (bh = bh->b_this_page) != head); |
| 1961 | |
| 1962 | if (fully_mapped) |
| 1963 | SetPageMappedToDisk(page); |
| 1964 | |
| 1965 | if (!nr) { |
| 1966 | /* |
| 1967 | * All buffers are uptodate - we can set the page uptodate |
| 1968 | * as well. But not if get_block() returned an error. |
| 1969 | */ |
| 1970 | if (!PageError(page)) |
| 1971 | SetPageUptodate(page); |
| 1972 | unlock_page(page); |
| 1973 | return 0; |
| 1974 | } |
| 1975 | |
| 1976 | /* Stage two: lock the buffers */ |
| 1977 | for (i = 0; i < nr; i++) { |
| 1978 | bh = arr[i]; |
| 1979 | lock_buffer(bh); |
| 1980 | mark_buffer_async_read(bh); |
| 1981 | } |
| 1982 | |
| 1983 | /* |
| 1984 | * Stage 3: start the IO. Check for uptodateness |
| 1985 | * inside the buffer lock in case another process reading |
| 1986 | * the underlying blockdev brought it uptodate (the sct fix). |
| 1987 | */ |
| 1988 | for (i = 0; i < nr; i++) { |
| 1989 | bh = arr[i]; |
| 1990 | if (buffer_uptodate(bh)) |
| 1991 | end_buffer_async_read(bh, 1); |
| 1992 | else |
| 1993 | submit_bh(READ, bh); |
| 1994 | } |
| 1995 | return 0; |
| 1996 | } |
| 1997 | |
| 1998 | /* utility function for filesystems that need to do work on expanding |
| 1999 | * truncates. Uses prepare/commit_write to allow the filesystem to |
| 2000 | * deal with the hole. |
| 2001 | */ |
OGAWA Hirofumi | 05eb0b5 | 2006-01-08 01:02:13 -0800 | [diff] [blame] | 2002 | static int __generic_cont_expand(struct inode *inode, loff_t size, |
| 2003 | pgoff_t index, unsigned int offset) |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 2004 | { |
| 2005 | struct address_space *mapping = inode->i_mapping; |
| 2006 | struct page *page; |
OGAWA Hirofumi | 05eb0b5 | 2006-01-08 01:02:13 -0800 | [diff] [blame] | 2007 | unsigned long limit; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 2008 | int err; |
| 2009 | |
| 2010 | err = -EFBIG; |
| 2011 | limit = current->signal->rlim[RLIMIT_FSIZE].rlim_cur; |
| 2012 | if (limit != RLIM_INFINITY && size > (loff_t)limit) { |
| 2013 | send_sig(SIGXFSZ, current, 0); |
| 2014 | goto out; |
| 2015 | } |
| 2016 | if (size > inode->i_sb->s_maxbytes) |
| 2017 | goto out; |
| 2018 | |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 2019 | err = -ENOMEM; |
| 2020 | page = grab_cache_page(mapping, index); |
| 2021 | if (!page) |
| 2022 | goto out; |
| 2023 | err = mapping->a_ops->prepare_write(NULL, page, offset, offset); |
OGAWA Hirofumi | 05eb0b5 | 2006-01-08 01:02:13 -0800 | [diff] [blame] | 2024 | if (err) { |
| 2025 | /* |
| 2026 | * ->prepare_write() may have instantiated a few blocks |
| 2027 | * outside i_size. Trim these off again. |
| 2028 | */ |
| 2029 | unlock_page(page); |
| 2030 | page_cache_release(page); |
| 2031 | vmtruncate(inode, inode->i_size); |
| 2032 | goto out; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 2033 | } |
OGAWA Hirofumi | 05eb0b5 | 2006-01-08 01:02:13 -0800 | [diff] [blame] | 2034 | |
| 2035 | err = mapping->a_ops->commit_write(NULL, page, offset, offset); |
| 2036 | |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 2037 | unlock_page(page); |
| 2038 | page_cache_release(page); |
| 2039 | if (err > 0) |
| 2040 | err = 0; |
| 2041 | out: |
| 2042 | return err; |
| 2043 | } |
| 2044 | |
OGAWA Hirofumi | 05eb0b5 | 2006-01-08 01:02:13 -0800 | [diff] [blame] | 2045 | int generic_cont_expand(struct inode *inode, loff_t size) |
| 2046 | { |
| 2047 | pgoff_t index; |
| 2048 | unsigned int offset; |
| 2049 | |
| 2050 | offset = (size & (PAGE_CACHE_SIZE - 1)); /* Within page */ |
| 2051 | |
| 2052 | /* ugh. in prepare/commit_write, if from==to==start of block, we |
| 2053 | ** skip the prepare. make sure we never send an offset for the start |
| 2054 | ** of a block |
| 2055 | */ |
| 2056 | if ((offset & (inode->i_sb->s_blocksize - 1)) == 0) { |
| 2057 | /* caller must handle this extra byte. */ |
| 2058 | offset++; |
| 2059 | } |
| 2060 | index = size >> PAGE_CACHE_SHIFT; |
| 2061 | |
| 2062 | return __generic_cont_expand(inode, size, index, offset); |
| 2063 | } |
| 2064 | |
| 2065 | int generic_cont_expand_simple(struct inode *inode, loff_t size) |
| 2066 | { |
| 2067 | loff_t pos = size - 1; |
| 2068 | pgoff_t index = pos >> PAGE_CACHE_SHIFT; |
| 2069 | unsigned int offset = (pos & (PAGE_CACHE_SIZE - 1)) + 1; |
| 2070 | |
| 2071 | /* prepare/commit_write can handle even if from==to==start of block. */ |
| 2072 | return __generic_cont_expand(inode, size, index, offset); |
| 2073 | } |
| 2074 | |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 2075 | /* |
| 2076 | * For moronic filesystems that do not allow holes in file. |
| 2077 | * We may have to extend the file. |
| 2078 | */ |
| 2079 | |
| 2080 | int cont_prepare_write(struct page *page, unsigned offset, |
| 2081 | unsigned to, get_block_t *get_block, loff_t *bytes) |
| 2082 | { |
| 2083 | struct address_space *mapping = page->mapping; |
| 2084 | struct inode *inode = mapping->host; |
| 2085 | struct page *new_page; |
| 2086 | pgoff_t pgpos; |
| 2087 | long status; |
| 2088 | unsigned zerofrom; |
| 2089 | unsigned blocksize = 1 << inode->i_blkbits; |
| 2090 | void *kaddr; |
| 2091 | |
| 2092 | while(page->index > (pgpos = *bytes>>PAGE_CACHE_SHIFT)) { |
| 2093 | status = -ENOMEM; |
| 2094 | new_page = grab_cache_page(mapping, pgpos); |
| 2095 | if (!new_page) |
| 2096 | goto out; |
| 2097 | /* we might sleep */ |
| 2098 | if (*bytes>>PAGE_CACHE_SHIFT != pgpos) { |
| 2099 | unlock_page(new_page); |
| 2100 | page_cache_release(new_page); |
| 2101 | continue; |
| 2102 | } |
| 2103 | zerofrom = *bytes & ~PAGE_CACHE_MASK; |
| 2104 | if (zerofrom & (blocksize-1)) { |
| 2105 | *bytes |= (blocksize-1); |
| 2106 | (*bytes)++; |
| 2107 | } |
| 2108 | status = __block_prepare_write(inode, new_page, zerofrom, |
| 2109 | PAGE_CACHE_SIZE, get_block); |
| 2110 | if (status) |
| 2111 | goto out_unmap; |
| 2112 | kaddr = kmap_atomic(new_page, KM_USER0); |
| 2113 | memset(kaddr+zerofrom, 0, PAGE_CACHE_SIZE-zerofrom); |
| 2114 | flush_dcache_page(new_page); |
| 2115 | kunmap_atomic(kaddr, KM_USER0); |
| 2116 | generic_commit_write(NULL, new_page, zerofrom, PAGE_CACHE_SIZE); |
| 2117 | unlock_page(new_page); |
| 2118 | page_cache_release(new_page); |
| 2119 | } |
| 2120 | |
| 2121 | if (page->index < pgpos) { |
| 2122 | /* completely inside the area */ |
| 2123 | zerofrom = offset; |
| 2124 | } else { |
| 2125 | /* page covers the boundary, find the boundary offset */ |
| 2126 | zerofrom = *bytes & ~PAGE_CACHE_MASK; |
| 2127 | |
| 2128 | /* if we will expand the thing last block will be filled */ |
| 2129 | if (to > zerofrom && (zerofrom & (blocksize-1))) { |
| 2130 | *bytes |= (blocksize-1); |
| 2131 | (*bytes)++; |
| 2132 | } |
| 2133 | |
| 2134 | /* starting below the boundary? Nothing to zero out */ |
| 2135 | if (offset <= zerofrom) |
| 2136 | zerofrom = offset; |
| 2137 | } |
| 2138 | status = __block_prepare_write(inode, page, zerofrom, to, get_block); |
| 2139 | if (status) |
| 2140 | goto out1; |
| 2141 | if (zerofrom < offset) { |
| 2142 | kaddr = kmap_atomic(page, KM_USER0); |
| 2143 | memset(kaddr+zerofrom, 0, offset-zerofrom); |
| 2144 | flush_dcache_page(page); |
| 2145 | kunmap_atomic(kaddr, KM_USER0); |
| 2146 | __block_commit_write(inode, page, zerofrom, offset); |
| 2147 | } |
| 2148 | return 0; |
| 2149 | out1: |
| 2150 | ClearPageUptodate(page); |
| 2151 | return status; |
| 2152 | |
| 2153 | out_unmap: |
| 2154 | ClearPageUptodate(new_page); |
| 2155 | unlock_page(new_page); |
| 2156 | page_cache_release(new_page); |
| 2157 | out: |
| 2158 | return status; |
| 2159 | } |
| 2160 | |
| 2161 | int block_prepare_write(struct page *page, unsigned from, unsigned to, |
| 2162 | get_block_t *get_block) |
| 2163 | { |
| 2164 | struct inode *inode = page->mapping->host; |
| 2165 | int err = __block_prepare_write(inode, page, from, to, get_block); |
| 2166 | if (err) |
| 2167 | ClearPageUptodate(page); |
| 2168 | return err; |
| 2169 | } |
| 2170 | |
| 2171 | int block_commit_write(struct page *page, unsigned from, unsigned to) |
| 2172 | { |
| 2173 | struct inode *inode = page->mapping->host; |
| 2174 | __block_commit_write(inode,page,from,to); |
| 2175 | return 0; |
| 2176 | } |
| 2177 | |
| 2178 | int generic_commit_write(struct file *file, struct page *page, |
| 2179 | unsigned from, unsigned to) |
| 2180 | { |
| 2181 | struct inode *inode = page->mapping->host; |
| 2182 | loff_t pos = ((loff_t)page->index << PAGE_CACHE_SHIFT) + to; |
| 2183 | __block_commit_write(inode,page,from,to); |
| 2184 | /* |
| 2185 | * No need to use i_size_read() here, the i_size |
Jes Sorensen | 1b1dcc1 | 2006-01-09 15:59:24 -0800 | [diff] [blame] | 2186 | * cannot change under us because we hold i_mutex. |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 2187 | */ |
| 2188 | if (pos > inode->i_size) { |
| 2189 | i_size_write(inode, pos); |
| 2190 | mark_inode_dirty(inode); |
| 2191 | } |
| 2192 | return 0; |
| 2193 | } |
| 2194 | |
| 2195 | |
| 2196 | /* |
| 2197 | * nobh_prepare_write()'s prereads are special: the buffer_heads are freed |
| 2198 | * immediately, while under the page lock. So it needs a special end_io |
| 2199 | * handler which does not touch the bh after unlocking it. |
| 2200 | * |
| 2201 | * Note: unlock_buffer() sort-of does touch the bh after unlocking it, but |
| 2202 | * a race there is benign: unlock_buffer() only use the bh's address for |
| 2203 | * hashing after unlocking the buffer, so it doesn't actually touch the bh |
| 2204 | * itself. |
| 2205 | */ |
| 2206 | static void end_buffer_read_nobh(struct buffer_head *bh, int uptodate) |
| 2207 | { |
| 2208 | if (uptodate) { |
| 2209 | set_buffer_uptodate(bh); |
| 2210 | } else { |
| 2211 | /* This happens, due to failed READA attempts. */ |
| 2212 | clear_buffer_uptodate(bh); |
| 2213 | } |
| 2214 | unlock_buffer(bh); |
| 2215 | } |
| 2216 | |
| 2217 | /* |
| 2218 | * On entry, the page is fully not uptodate. |
| 2219 | * On exit the page is fully uptodate in the areas outside (from,to) |
| 2220 | */ |
| 2221 | int nobh_prepare_write(struct page *page, unsigned from, unsigned to, |
| 2222 | get_block_t *get_block) |
| 2223 | { |
| 2224 | struct inode *inode = page->mapping->host; |
| 2225 | const unsigned blkbits = inode->i_blkbits; |
| 2226 | const unsigned blocksize = 1 << blkbits; |
| 2227 | struct buffer_head map_bh; |
| 2228 | struct buffer_head *read_bh[MAX_BUF_PER_PAGE]; |
| 2229 | unsigned block_in_page; |
| 2230 | unsigned block_start; |
| 2231 | sector_t block_in_file; |
| 2232 | char *kaddr; |
| 2233 | int nr_reads = 0; |
| 2234 | int i; |
| 2235 | int ret = 0; |
| 2236 | int is_mapped_to_disk = 1; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 2237 | |
| 2238 | if (PageMappedToDisk(page)) |
| 2239 | return 0; |
| 2240 | |
| 2241 | block_in_file = (sector_t)page->index << (PAGE_CACHE_SHIFT - blkbits); |
| 2242 | map_bh.b_page = page; |
| 2243 | |
| 2244 | /* |
| 2245 | * We loop across all blocks in the page, whether or not they are |
| 2246 | * part of the affected region. This is so we can discover if the |
| 2247 | * page is fully mapped-to-disk. |
| 2248 | */ |
| 2249 | for (block_start = 0, block_in_page = 0; |
| 2250 | block_start < PAGE_CACHE_SIZE; |
| 2251 | block_in_page++, block_start += blocksize) { |
| 2252 | unsigned block_end = block_start + blocksize; |
| 2253 | int create; |
| 2254 | |
| 2255 | map_bh.b_state = 0; |
| 2256 | create = 1; |
| 2257 | if (block_start >= to) |
| 2258 | create = 0; |
Badari Pulavarty | b0cf232 | 2006-03-26 01:38:00 -0800 | [diff] [blame] | 2259 | map_bh.b_size = blocksize; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 2260 | ret = get_block(inode, block_in_file + block_in_page, |
| 2261 | &map_bh, create); |
| 2262 | if (ret) |
| 2263 | goto failed; |
| 2264 | if (!buffer_mapped(&map_bh)) |
| 2265 | is_mapped_to_disk = 0; |
| 2266 | if (buffer_new(&map_bh)) |
| 2267 | unmap_underlying_metadata(map_bh.b_bdev, |
| 2268 | map_bh.b_blocknr); |
| 2269 | if (PageUptodate(page)) |
| 2270 | continue; |
| 2271 | if (buffer_new(&map_bh) || !buffer_mapped(&map_bh)) { |
| 2272 | kaddr = kmap_atomic(page, KM_USER0); |
Nick Piggin | 22c8ca7 | 2007-02-20 13:58:09 -0800 | [diff] [blame] | 2273 | if (block_start < from) |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 2274 | memset(kaddr+block_start, 0, from-block_start); |
Nick Piggin | 22c8ca7 | 2007-02-20 13:58:09 -0800 | [diff] [blame] | 2275 | if (block_end > to) |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 2276 | memset(kaddr + to, 0, block_end - to); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 2277 | flush_dcache_page(page); |
| 2278 | kunmap_atomic(kaddr, KM_USER0); |
| 2279 | continue; |
| 2280 | } |
| 2281 | if (buffer_uptodate(&map_bh)) |
| 2282 | continue; /* reiserfs does this */ |
| 2283 | if (block_start < from || block_end > to) { |
| 2284 | struct buffer_head *bh = alloc_buffer_head(GFP_NOFS); |
| 2285 | |
| 2286 | if (!bh) { |
| 2287 | ret = -ENOMEM; |
| 2288 | goto failed; |
| 2289 | } |
| 2290 | bh->b_state = map_bh.b_state; |
| 2291 | atomic_set(&bh->b_count, 0); |
| 2292 | bh->b_this_page = NULL; |
| 2293 | bh->b_page = page; |
| 2294 | bh->b_blocknr = map_bh.b_blocknr; |
| 2295 | bh->b_size = blocksize; |
| 2296 | bh->b_data = (char *)(long)block_start; |
| 2297 | bh->b_bdev = map_bh.b_bdev; |
| 2298 | bh->b_private = NULL; |
| 2299 | read_bh[nr_reads++] = bh; |
| 2300 | } |
| 2301 | } |
| 2302 | |
| 2303 | if (nr_reads) { |
| 2304 | struct buffer_head *bh; |
| 2305 | |
| 2306 | /* |
| 2307 | * The page is locked, so these buffers are protected from |
| 2308 | * any VM or truncate activity. Hence we don't need to care |
| 2309 | * for the buffer_head refcounts. |
| 2310 | */ |
| 2311 | for (i = 0; i < nr_reads; i++) { |
| 2312 | bh = read_bh[i]; |
| 2313 | lock_buffer(bh); |
| 2314 | bh->b_end_io = end_buffer_read_nobh; |
| 2315 | submit_bh(READ, bh); |
| 2316 | } |
| 2317 | for (i = 0; i < nr_reads; i++) { |
| 2318 | bh = read_bh[i]; |
| 2319 | wait_on_buffer(bh); |
| 2320 | if (!buffer_uptodate(bh)) |
| 2321 | ret = -EIO; |
| 2322 | free_buffer_head(bh); |
| 2323 | read_bh[i] = NULL; |
| 2324 | } |
| 2325 | if (ret) |
| 2326 | goto failed; |
| 2327 | } |
| 2328 | |
| 2329 | if (is_mapped_to_disk) |
| 2330 | SetPageMappedToDisk(page); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 2331 | |
| 2332 | return 0; |
| 2333 | |
| 2334 | failed: |
| 2335 | for (i = 0; i < nr_reads; i++) { |
| 2336 | if (read_bh[i]) |
| 2337 | free_buffer_head(read_bh[i]); |
| 2338 | } |
| 2339 | |
| 2340 | /* |
| 2341 | * Error recovery is pretty slack. Clear the page and mark it dirty |
| 2342 | * so we'll later zero out any blocks which _were_ allocated. |
| 2343 | */ |
| 2344 | kaddr = kmap_atomic(page, KM_USER0); |
| 2345 | memset(kaddr, 0, PAGE_CACHE_SIZE); |
Monakhov Dmitriy | 8c58165 | 2006-10-11 01:22:00 -0700 | [diff] [blame] | 2346 | flush_dcache_page(page); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 2347 | kunmap_atomic(kaddr, KM_USER0); |
| 2348 | SetPageUptodate(page); |
| 2349 | set_page_dirty(page); |
| 2350 | return ret; |
| 2351 | } |
| 2352 | EXPORT_SYMBOL(nobh_prepare_write); |
| 2353 | |
Dave Kleikamp | 57bf63d | 2007-03-06 01:42:12 -0800 | [diff] [blame] | 2354 | /* |
| 2355 | * Make sure any changes to nobh_commit_write() are reflected in |
| 2356 | * nobh_truncate_page(), since it doesn't call commit_write(). |
| 2357 | */ |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 2358 | int nobh_commit_write(struct file *file, struct page *page, |
| 2359 | unsigned from, unsigned to) |
| 2360 | { |
| 2361 | struct inode *inode = page->mapping->host; |
| 2362 | loff_t pos = ((loff_t)page->index << PAGE_CACHE_SHIFT) + to; |
| 2363 | |
Nick Piggin | 22c8ca7 | 2007-02-20 13:58:09 -0800 | [diff] [blame] | 2364 | SetPageUptodate(page); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 2365 | set_page_dirty(page); |
| 2366 | if (pos > inode->i_size) { |
| 2367 | i_size_write(inode, pos); |
| 2368 | mark_inode_dirty(inode); |
| 2369 | } |
| 2370 | return 0; |
| 2371 | } |
| 2372 | EXPORT_SYMBOL(nobh_commit_write); |
| 2373 | |
| 2374 | /* |
| 2375 | * nobh_writepage() - based on block_full_write_page() except |
| 2376 | * that it tries to operate without attaching bufferheads to |
| 2377 | * the page. |
| 2378 | */ |
| 2379 | int nobh_writepage(struct page *page, get_block_t *get_block, |
| 2380 | struct writeback_control *wbc) |
| 2381 | { |
| 2382 | struct inode * const inode = page->mapping->host; |
| 2383 | loff_t i_size = i_size_read(inode); |
| 2384 | const pgoff_t end_index = i_size >> PAGE_CACHE_SHIFT; |
| 2385 | unsigned offset; |
| 2386 | void *kaddr; |
| 2387 | int ret; |
| 2388 | |
| 2389 | /* Is the page fully inside i_size? */ |
| 2390 | if (page->index < end_index) |
| 2391 | goto out; |
| 2392 | |
| 2393 | /* Is the page fully outside i_size? (truncate in progress) */ |
| 2394 | offset = i_size & (PAGE_CACHE_SIZE-1); |
| 2395 | if (page->index >= end_index+1 || !offset) { |
| 2396 | /* |
| 2397 | * The page may have dirty, unmapped buffers. For example, |
| 2398 | * they may have been added in ext3_writepage(). Make them |
| 2399 | * freeable here, so the page does not leak. |
| 2400 | */ |
| 2401 | #if 0 |
| 2402 | /* Not really sure about this - do we need this ? */ |
| 2403 | if (page->mapping->a_ops->invalidatepage) |
| 2404 | page->mapping->a_ops->invalidatepage(page, offset); |
| 2405 | #endif |
| 2406 | unlock_page(page); |
| 2407 | return 0; /* don't care */ |
| 2408 | } |
| 2409 | |
| 2410 | /* |
| 2411 | * The page straddles i_size. It must be zeroed out on each and every |
| 2412 | * writepage invocation because it may be mmapped. "A file is mapped |
| 2413 | * in multiples of the page size. For a file that is not a multiple of |
| 2414 | * the page size, the remaining memory is zeroed when mapped, and |
| 2415 | * writes to that region are not written out to the file." |
| 2416 | */ |
| 2417 | kaddr = kmap_atomic(page, KM_USER0); |
| 2418 | memset(kaddr + offset, 0, PAGE_CACHE_SIZE - offset); |
| 2419 | flush_dcache_page(page); |
| 2420 | kunmap_atomic(kaddr, KM_USER0); |
| 2421 | out: |
| 2422 | ret = mpage_writepage(page, get_block, wbc); |
| 2423 | if (ret == -EAGAIN) |
| 2424 | ret = __block_write_full_page(inode, page, get_block, wbc); |
| 2425 | return ret; |
| 2426 | } |
| 2427 | EXPORT_SYMBOL(nobh_writepage); |
| 2428 | |
| 2429 | /* |
| 2430 | * This function assumes that ->prepare_write() uses nobh_prepare_write(). |
| 2431 | */ |
| 2432 | int nobh_truncate_page(struct address_space *mapping, loff_t from) |
| 2433 | { |
| 2434 | struct inode *inode = mapping->host; |
| 2435 | unsigned blocksize = 1 << inode->i_blkbits; |
| 2436 | pgoff_t index = from >> PAGE_CACHE_SHIFT; |
| 2437 | unsigned offset = from & (PAGE_CACHE_SIZE-1); |
| 2438 | unsigned to; |
| 2439 | struct page *page; |
Christoph Hellwig | f5e54d6 | 2006-06-28 04:26:44 -0700 | [diff] [blame] | 2440 | const struct address_space_operations *a_ops = mapping->a_ops; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 2441 | char *kaddr; |
| 2442 | int ret = 0; |
| 2443 | |
| 2444 | if ((offset & (blocksize - 1)) == 0) |
| 2445 | goto out; |
| 2446 | |
| 2447 | ret = -ENOMEM; |
| 2448 | page = grab_cache_page(mapping, index); |
| 2449 | if (!page) |
| 2450 | goto out; |
| 2451 | |
| 2452 | to = (offset + blocksize) & ~(blocksize - 1); |
| 2453 | ret = a_ops->prepare_write(NULL, page, offset, to); |
| 2454 | if (ret == 0) { |
| 2455 | kaddr = kmap_atomic(page, KM_USER0); |
| 2456 | memset(kaddr + offset, 0, PAGE_CACHE_SIZE - offset); |
| 2457 | flush_dcache_page(page); |
| 2458 | kunmap_atomic(kaddr, KM_USER0); |
Dave Kleikamp | 57bf63d | 2007-03-06 01:42:12 -0800 | [diff] [blame] | 2459 | /* |
| 2460 | * It would be more correct to call aops->commit_write() |
| 2461 | * here, but this is more efficient. |
| 2462 | */ |
| 2463 | SetPageUptodate(page); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 2464 | set_page_dirty(page); |
| 2465 | } |
| 2466 | unlock_page(page); |
| 2467 | page_cache_release(page); |
| 2468 | out: |
| 2469 | return ret; |
| 2470 | } |
| 2471 | EXPORT_SYMBOL(nobh_truncate_page); |
| 2472 | |
| 2473 | int block_truncate_page(struct address_space *mapping, |
| 2474 | loff_t from, get_block_t *get_block) |
| 2475 | { |
| 2476 | pgoff_t index = from >> PAGE_CACHE_SHIFT; |
| 2477 | unsigned offset = from & (PAGE_CACHE_SIZE-1); |
| 2478 | unsigned blocksize; |
Andrew Morton | 54b21a7 | 2006-01-08 01:03:05 -0800 | [diff] [blame] | 2479 | sector_t iblock; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 2480 | unsigned length, pos; |
| 2481 | struct inode *inode = mapping->host; |
| 2482 | struct page *page; |
| 2483 | struct buffer_head *bh; |
| 2484 | void *kaddr; |
| 2485 | int err; |
| 2486 | |
| 2487 | blocksize = 1 << inode->i_blkbits; |
| 2488 | length = offset & (blocksize - 1); |
| 2489 | |
| 2490 | /* Block boundary? Nothing to do */ |
| 2491 | if (!length) |
| 2492 | return 0; |
| 2493 | |
| 2494 | length = blocksize - length; |
Andrew Morton | 54b21a7 | 2006-01-08 01:03:05 -0800 | [diff] [blame] | 2495 | iblock = (sector_t)index << (PAGE_CACHE_SHIFT - inode->i_blkbits); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 2496 | |
| 2497 | page = grab_cache_page(mapping, index); |
| 2498 | err = -ENOMEM; |
| 2499 | if (!page) |
| 2500 | goto out; |
| 2501 | |
| 2502 | if (!page_has_buffers(page)) |
| 2503 | create_empty_buffers(page, blocksize, 0); |
| 2504 | |
| 2505 | /* Find the buffer that contains "offset" */ |
| 2506 | bh = page_buffers(page); |
| 2507 | pos = blocksize; |
| 2508 | while (offset >= pos) { |
| 2509 | bh = bh->b_this_page; |
| 2510 | iblock++; |
| 2511 | pos += blocksize; |
| 2512 | } |
| 2513 | |
| 2514 | err = 0; |
| 2515 | if (!buffer_mapped(bh)) { |
Badari Pulavarty | b0cf232 | 2006-03-26 01:38:00 -0800 | [diff] [blame] | 2516 | WARN_ON(bh->b_size != blocksize); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 2517 | err = get_block(inode, iblock, bh, 0); |
| 2518 | if (err) |
| 2519 | goto unlock; |
| 2520 | /* unmapped? It's a hole - nothing to do */ |
| 2521 | if (!buffer_mapped(bh)) |
| 2522 | goto unlock; |
| 2523 | } |
| 2524 | |
| 2525 | /* Ok, it's mapped. Make sure it's up-to-date */ |
| 2526 | if (PageUptodate(page)) |
| 2527 | set_buffer_uptodate(bh); |
| 2528 | |
David Chinner | 33a266d | 2007-02-12 00:51:41 -0800 | [diff] [blame] | 2529 | if (!buffer_uptodate(bh) && !buffer_delay(bh) && !buffer_unwritten(bh)) { |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 2530 | err = -EIO; |
| 2531 | ll_rw_block(READ, 1, &bh); |
| 2532 | wait_on_buffer(bh); |
| 2533 | /* Uhhuh. Read error. Complain and punt. */ |
| 2534 | if (!buffer_uptodate(bh)) |
| 2535 | goto unlock; |
| 2536 | } |
| 2537 | |
| 2538 | kaddr = kmap_atomic(page, KM_USER0); |
| 2539 | memset(kaddr + offset, 0, length); |
| 2540 | flush_dcache_page(page); |
| 2541 | kunmap_atomic(kaddr, KM_USER0); |
| 2542 | |
| 2543 | mark_buffer_dirty(bh); |
| 2544 | err = 0; |
| 2545 | |
| 2546 | unlock: |
| 2547 | unlock_page(page); |
| 2548 | page_cache_release(page); |
| 2549 | out: |
| 2550 | return err; |
| 2551 | } |
| 2552 | |
| 2553 | /* |
| 2554 | * The generic ->writepage function for buffer-backed address_spaces |
| 2555 | */ |
| 2556 | int block_write_full_page(struct page *page, get_block_t *get_block, |
| 2557 | struct writeback_control *wbc) |
| 2558 | { |
| 2559 | struct inode * const inode = page->mapping->host; |
| 2560 | loff_t i_size = i_size_read(inode); |
| 2561 | const pgoff_t end_index = i_size >> PAGE_CACHE_SHIFT; |
| 2562 | unsigned offset; |
| 2563 | void *kaddr; |
| 2564 | |
| 2565 | /* Is the page fully inside i_size? */ |
| 2566 | if (page->index < end_index) |
| 2567 | return __block_write_full_page(inode, page, get_block, wbc); |
| 2568 | |
| 2569 | /* Is the page fully outside i_size? (truncate in progress) */ |
| 2570 | offset = i_size & (PAGE_CACHE_SIZE-1); |
| 2571 | if (page->index >= end_index+1 || !offset) { |
| 2572 | /* |
| 2573 | * The page may have dirty, unmapped buffers. For example, |
| 2574 | * they may have been added in ext3_writepage(). Make them |
| 2575 | * freeable here, so the page does not leak. |
| 2576 | */ |
Jan Kara | aaa4059 | 2005-10-30 15:00:16 -0800 | [diff] [blame] | 2577 | do_invalidatepage(page, 0); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 2578 | unlock_page(page); |
| 2579 | return 0; /* don't care */ |
| 2580 | } |
| 2581 | |
| 2582 | /* |
| 2583 | * The page straddles i_size. It must be zeroed out on each and every |
| 2584 | * writepage invokation because it may be mmapped. "A file is mapped |
| 2585 | * in multiples of the page size. For a file that is not a multiple of |
| 2586 | * the page size, the remaining memory is zeroed when mapped, and |
| 2587 | * writes to that region are not written out to the file." |
| 2588 | */ |
| 2589 | kaddr = kmap_atomic(page, KM_USER0); |
| 2590 | memset(kaddr + offset, 0, PAGE_CACHE_SIZE - offset); |
| 2591 | flush_dcache_page(page); |
| 2592 | kunmap_atomic(kaddr, KM_USER0); |
| 2593 | return __block_write_full_page(inode, page, get_block, wbc); |
| 2594 | } |
| 2595 | |
| 2596 | sector_t generic_block_bmap(struct address_space *mapping, sector_t block, |
| 2597 | get_block_t *get_block) |
| 2598 | { |
| 2599 | struct buffer_head tmp; |
| 2600 | struct inode *inode = mapping->host; |
| 2601 | tmp.b_state = 0; |
| 2602 | tmp.b_blocknr = 0; |
Badari Pulavarty | b0cf232 | 2006-03-26 01:38:00 -0800 | [diff] [blame] | 2603 | tmp.b_size = 1 << inode->i_blkbits; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 2604 | get_block(inode, block, &tmp, 0); |
| 2605 | return tmp.b_blocknr; |
| 2606 | } |
| 2607 | |
| 2608 | static int end_bio_bh_io_sync(struct bio *bio, unsigned int bytes_done, int err) |
| 2609 | { |
| 2610 | struct buffer_head *bh = bio->bi_private; |
| 2611 | |
| 2612 | if (bio->bi_size) |
| 2613 | return 1; |
| 2614 | |
| 2615 | if (err == -EOPNOTSUPP) { |
| 2616 | set_bit(BIO_EOPNOTSUPP, &bio->bi_flags); |
| 2617 | set_bit(BH_Eopnotsupp, &bh->b_state); |
| 2618 | } |
| 2619 | |
| 2620 | bh->b_end_io(bh, test_bit(BIO_UPTODATE, &bio->bi_flags)); |
| 2621 | bio_put(bio); |
| 2622 | return 0; |
| 2623 | } |
| 2624 | |
| 2625 | int submit_bh(int rw, struct buffer_head * bh) |
| 2626 | { |
| 2627 | struct bio *bio; |
| 2628 | int ret = 0; |
| 2629 | |
| 2630 | BUG_ON(!buffer_locked(bh)); |
| 2631 | BUG_ON(!buffer_mapped(bh)); |
| 2632 | BUG_ON(!bh->b_end_io); |
| 2633 | |
| 2634 | if (buffer_ordered(bh) && (rw == WRITE)) |
| 2635 | rw = WRITE_BARRIER; |
| 2636 | |
| 2637 | /* |
| 2638 | * Only clear out a write error when rewriting, should this |
| 2639 | * include WRITE_SYNC as well? |
| 2640 | */ |
| 2641 | if (test_set_buffer_req(bh) && (rw == WRITE || rw == WRITE_BARRIER)) |
| 2642 | clear_buffer_write_io_error(bh); |
| 2643 | |
| 2644 | /* |
| 2645 | * from here on down, it's all bio -- do the initial mapping, |
| 2646 | * submit_bio -> generic_make_request may further map this bio around |
| 2647 | */ |
| 2648 | bio = bio_alloc(GFP_NOIO, 1); |
| 2649 | |
| 2650 | bio->bi_sector = bh->b_blocknr * (bh->b_size >> 9); |
| 2651 | bio->bi_bdev = bh->b_bdev; |
| 2652 | bio->bi_io_vec[0].bv_page = bh->b_page; |
| 2653 | bio->bi_io_vec[0].bv_len = bh->b_size; |
| 2654 | bio->bi_io_vec[0].bv_offset = bh_offset(bh); |
| 2655 | |
| 2656 | bio->bi_vcnt = 1; |
| 2657 | bio->bi_idx = 0; |
| 2658 | bio->bi_size = bh->b_size; |
| 2659 | |
| 2660 | bio->bi_end_io = end_bio_bh_io_sync; |
| 2661 | bio->bi_private = bh; |
| 2662 | |
| 2663 | bio_get(bio); |
| 2664 | submit_bio(rw, bio); |
| 2665 | |
| 2666 | if (bio_flagged(bio, BIO_EOPNOTSUPP)) |
| 2667 | ret = -EOPNOTSUPP; |
| 2668 | |
| 2669 | bio_put(bio); |
| 2670 | return ret; |
| 2671 | } |
| 2672 | |
| 2673 | /** |
| 2674 | * ll_rw_block: low-level access to block devices (DEPRECATED) |
Jan Kara | a766223 | 2005-09-06 15:19:10 -0700 | [diff] [blame] | 2675 | * @rw: whether to %READ or %WRITE or %SWRITE or maybe %READA (readahead) |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 2676 | * @nr: number of &struct buffer_heads in the array |
| 2677 | * @bhs: array of pointers to &struct buffer_head |
| 2678 | * |
Jan Kara | a766223 | 2005-09-06 15:19:10 -0700 | [diff] [blame] | 2679 | * ll_rw_block() takes an array of pointers to &struct buffer_heads, and |
| 2680 | * requests an I/O operation on them, either a %READ or a %WRITE. The third |
| 2681 | * %SWRITE is like %WRITE only we make sure that the *current* data in buffers |
| 2682 | * are sent to disk. The fourth %READA option is described in the documentation |
| 2683 | * for generic_make_request() which ll_rw_block() calls. |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 2684 | * |
| 2685 | * This function drops any buffer that it cannot get a lock on (with the |
Jan Kara | a766223 | 2005-09-06 15:19:10 -0700 | [diff] [blame] | 2686 | * BH_Lock state bit) unless SWRITE is required, any buffer that appears to be |
| 2687 | * clean when doing a write request, and any buffer that appears to be |
| 2688 | * up-to-date when doing read request. Further it marks as clean buffers that |
| 2689 | * are processed for writing (the buffer cache won't assume that they are |
| 2690 | * actually clean until the buffer gets unlocked). |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 2691 | * |
| 2692 | * ll_rw_block sets b_end_io to simple completion handler that marks |
| 2693 | * the buffer up-to-date (if approriate), unlocks the buffer and wakes |
| 2694 | * any waiters. |
| 2695 | * |
| 2696 | * All of the buffers must be for the same device, and must also be a |
| 2697 | * multiple of the current approved size for the device. |
| 2698 | */ |
| 2699 | void ll_rw_block(int rw, int nr, struct buffer_head *bhs[]) |
| 2700 | { |
| 2701 | int i; |
| 2702 | |
| 2703 | for (i = 0; i < nr; i++) { |
| 2704 | struct buffer_head *bh = bhs[i]; |
| 2705 | |
Jan Kara | a766223 | 2005-09-06 15:19:10 -0700 | [diff] [blame] | 2706 | if (rw == SWRITE) |
| 2707 | lock_buffer(bh); |
| 2708 | else if (test_set_buffer_locked(bh)) |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 2709 | continue; |
| 2710 | |
Jan Kara | a766223 | 2005-09-06 15:19:10 -0700 | [diff] [blame] | 2711 | if (rw == WRITE || rw == SWRITE) { |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 2712 | if (test_clear_buffer_dirty(bh)) { |
akpm@osdl.org | 76c3073 | 2005-04-16 15:24:07 -0700 | [diff] [blame] | 2713 | bh->b_end_io = end_buffer_write_sync; |
OGAWA Hirofumi | e60e5c5 | 2006-02-03 03:04:43 -0800 | [diff] [blame] | 2714 | get_bh(bh); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 2715 | submit_bh(WRITE, bh); |
| 2716 | continue; |
| 2717 | } |
| 2718 | } else { |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 2719 | if (!buffer_uptodate(bh)) { |
akpm@osdl.org | 76c3073 | 2005-04-16 15:24:07 -0700 | [diff] [blame] | 2720 | bh->b_end_io = end_buffer_read_sync; |
OGAWA Hirofumi | e60e5c5 | 2006-02-03 03:04:43 -0800 | [diff] [blame] | 2721 | get_bh(bh); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 2722 | submit_bh(rw, bh); |
| 2723 | continue; |
| 2724 | } |
| 2725 | } |
| 2726 | unlock_buffer(bh); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 2727 | } |
| 2728 | } |
| 2729 | |
| 2730 | /* |
| 2731 | * For a data-integrity writeout, we need to wait upon any in-progress I/O |
| 2732 | * and then start new I/O and then wait upon it. The caller must have a ref on |
| 2733 | * the buffer_head. |
| 2734 | */ |
| 2735 | int sync_dirty_buffer(struct buffer_head *bh) |
| 2736 | { |
| 2737 | int ret = 0; |
| 2738 | |
| 2739 | WARN_ON(atomic_read(&bh->b_count) < 1); |
| 2740 | lock_buffer(bh); |
| 2741 | if (test_clear_buffer_dirty(bh)) { |
| 2742 | get_bh(bh); |
| 2743 | bh->b_end_io = end_buffer_write_sync; |
| 2744 | ret = submit_bh(WRITE, bh); |
| 2745 | wait_on_buffer(bh); |
| 2746 | if (buffer_eopnotsupp(bh)) { |
| 2747 | clear_buffer_eopnotsupp(bh); |
| 2748 | ret = -EOPNOTSUPP; |
| 2749 | } |
| 2750 | if (!ret && !buffer_uptodate(bh)) |
| 2751 | ret = -EIO; |
| 2752 | } else { |
| 2753 | unlock_buffer(bh); |
| 2754 | } |
| 2755 | return ret; |
| 2756 | } |
| 2757 | |
| 2758 | /* |
| 2759 | * try_to_free_buffers() checks if all the buffers on this particular page |
| 2760 | * are unused, and releases them if so. |
| 2761 | * |
| 2762 | * Exclusion against try_to_free_buffers may be obtained by either |
| 2763 | * locking the page or by holding its mapping's private_lock. |
| 2764 | * |
| 2765 | * If the page is dirty but all the buffers are clean then we need to |
| 2766 | * be sure to mark the page clean as well. This is because the page |
| 2767 | * may be against a block device, and a later reattachment of buffers |
| 2768 | * to a dirty page will set *all* buffers dirty. Which would corrupt |
| 2769 | * filesystem data on the same device. |
| 2770 | * |
| 2771 | * The same applies to regular filesystem pages: if all the buffers are |
| 2772 | * clean then we set the page clean and proceed. To do that, we require |
| 2773 | * total exclusion from __set_page_dirty_buffers(). That is obtained with |
| 2774 | * private_lock. |
| 2775 | * |
| 2776 | * try_to_free_buffers() is non-blocking. |
| 2777 | */ |
| 2778 | static inline int buffer_busy(struct buffer_head *bh) |
| 2779 | { |
| 2780 | return atomic_read(&bh->b_count) | |
| 2781 | (bh->b_state & ((1 << BH_Dirty) | (1 << BH_Lock))); |
| 2782 | } |
| 2783 | |
| 2784 | static int |
| 2785 | drop_buffers(struct page *page, struct buffer_head **buffers_to_free) |
| 2786 | { |
| 2787 | struct buffer_head *head = page_buffers(page); |
| 2788 | struct buffer_head *bh; |
| 2789 | |
| 2790 | bh = head; |
| 2791 | do { |
akpm@osdl.org | de7d5a3 | 2005-05-01 08:58:39 -0700 | [diff] [blame] | 2792 | if (buffer_write_io_error(bh) && page->mapping) |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 2793 | set_bit(AS_EIO, &page->mapping->flags); |
| 2794 | if (buffer_busy(bh)) |
| 2795 | goto failed; |
| 2796 | bh = bh->b_this_page; |
| 2797 | } while (bh != head); |
| 2798 | |
| 2799 | do { |
| 2800 | struct buffer_head *next = bh->b_this_page; |
| 2801 | |
| 2802 | if (!list_empty(&bh->b_assoc_buffers)) |
| 2803 | __remove_assoc_queue(bh); |
| 2804 | bh = next; |
| 2805 | } while (bh != head); |
| 2806 | *buffers_to_free = head; |
| 2807 | __clear_page_buffers(page); |
| 2808 | return 1; |
| 2809 | failed: |
| 2810 | return 0; |
| 2811 | } |
| 2812 | |
| 2813 | int try_to_free_buffers(struct page *page) |
| 2814 | { |
| 2815 | struct address_space * const mapping = page->mapping; |
| 2816 | struct buffer_head *buffers_to_free = NULL; |
| 2817 | int ret = 0; |
| 2818 | |
| 2819 | BUG_ON(!PageLocked(page)); |
Linus Torvalds | ecdfc97 | 2007-01-26 12:47:06 -0800 | [diff] [blame] | 2820 | if (PageWriteback(page)) |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 2821 | return 0; |
| 2822 | |
| 2823 | if (mapping == NULL) { /* can this still happen? */ |
| 2824 | ret = drop_buffers(page, &buffers_to_free); |
| 2825 | goto out; |
| 2826 | } |
| 2827 | |
| 2828 | spin_lock(&mapping->private_lock); |
| 2829 | ret = drop_buffers(page, &buffers_to_free); |
Linus Torvalds | ecdfc97 | 2007-01-26 12:47:06 -0800 | [diff] [blame] | 2830 | |
| 2831 | /* |
| 2832 | * If the filesystem writes its buffers by hand (eg ext3) |
| 2833 | * then we can have clean buffers against a dirty page. We |
| 2834 | * clean the page here; otherwise the VM will never notice |
| 2835 | * that the filesystem did any IO at all. |
| 2836 | * |
| 2837 | * Also, during truncate, discard_buffer will have marked all |
| 2838 | * the page's buffers clean. We discover that here and clean |
| 2839 | * the page also. |
Nick Piggin | 87df724 | 2007-01-30 14:36:27 +1100 | [diff] [blame] | 2840 | * |
| 2841 | * private_lock must be held over this entire operation in order |
| 2842 | * to synchronise against __set_page_dirty_buffers and prevent the |
| 2843 | * dirty bit from being lost. |
Linus Torvalds | ecdfc97 | 2007-01-26 12:47:06 -0800 | [diff] [blame] | 2844 | */ |
| 2845 | if (ret) |
| 2846 | cancel_dirty_page(page, PAGE_CACHE_SIZE); |
Nick Piggin | 87df724 | 2007-01-30 14:36:27 +1100 | [diff] [blame] | 2847 | spin_unlock(&mapping->private_lock); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 2848 | out: |
| 2849 | if (buffers_to_free) { |
| 2850 | struct buffer_head *bh = buffers_to_free; |
| 2851 | |
| 2852 | do { |
| 2853 | struct buffer_head *next = bh->b_this_page; |
| 2854 | free_buffer_head(bh); |
| 2855 | bh = next; |
| 2856 | } while (bh != buffers_to_free); |
| 2857 | } |
| 2858 | return ret; |
| 2859 | } |
| 2860 | EXPORT_SYMBOL(try_to_free_buffers); |
| 2861 | |
NeilBrown | 3978d71 | 2006-03-26 01:37:17 -0800 | [diff] [blame] | 2862 | void block_sync_page(struct page *page) |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 2863 | { |
| 2864 | struct address_space *mapping; |
| 2865 | |
| 2866 | smp_mb(); |
| 2867 | mapping = page_mapping(page); |
| 2868 | if (mapping) |
| 2869 | blk_run_backing_dev(mapping->backing_dev_info, page); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 2870 | } |
| 2871 | |
| 2872 | /* |
| 2873 | * There are no bdflush tunables left. But distributions are |
| 2874 | * still running obsolete flush daemons, so we terminate them here. |
| 2875 | * |
| 2876 | * Use of bdflush() is deprecated and will be removed in a future kernel. |
| 2877 | * The `pdflush' kernel threads fully replace bdflush daemons and this call. |
| 2878 | */ |
| 2879 | asmlinkage long sys_bdflush(int func, long data) |
| 2880 | { |
| 2881 | static int msg_count; |
| 2882 | |
| 2883 | if (!capable(CAP_SYS_ADMIN)) |
| 2884 | return -EPERM; |
| 2885 | |
| 2886 | if (msg_count < 5) { |
| 2887 | msg_count++; |
| 2888 | printk(KERN_INFO |
| 2889 | "warning: process `%s' used the obsolete bdflush" |
| 2890 | " system call\n", current->comm); |
| 2891 | printk(KERN_INFO "Fix your initscripts?\n"); |
| 2892 | } |
| 2893 | |
| 2894 | if (func == 1) |
| 2895 | do_exit(0); |
| 2896 | return 0; |
| 2897 | } |
| 2898 | |
| 2899 | /* |
| 2900 | * Buffer-head allocation |
| 2901 | */ |
Christoph Lameter | e18b890 | 2006-12-06 20:33:20 -0800 | [diff] [blame] | 2902 | static struct kmem_cache *bh_cachep; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 2903 | |
| 2904 | /* |
| 2905 | * Once the number of bh's in the machine exceeds this level, we start |
| 2906 | * stripping them in writeback. |
| 2907 | */ |
| 2908 | static int max_buffer_heads; |
| 2909 | |
| 2910 | int buffer_heads_over_limit; |
| 2911 | |
| 2912 | struct bh_accounting { |
| 2913 | int nr; /* Number of live bh's */ |
| 2914 | int ratelimit; /* Limit cacheline bouncing */ |
| 2915 | }; |
| 2916 | |
| 2917 | static DEFINE_PER_CPU(struct bh_accounting, bh_accounting) = {0, 0}; |
| 2918 | |
| 2919 | static void recalc_bh_state(void) |
| 2920 | { |
| 2921 | int i; |
| 2922 | int tot = 0; |
| 2923 | |
| 2924 | if (__get_cpu_var(bh_accounting).ratelimit++ < 4096) |
| 2925 | return; |
| 2926 | __get_cpu_var(bh_accounting).ratelimit = 0; |
Eric Dumazet | 8a14342 | 2006-03-24 03:18:10 -0800 | [diff] [blame] | 2927 | for_each_online_cpu(i) |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 2928 | tot += per_cpu(bh_accounting, i).nr; |
| 2929 | buffer_heads_over_limit = (tot > max_buffer_heads); |
| 2930 | } |
| 2931 | |
Al Viro | dd0fc66 | 2005-10-07 07:46:04 +0100 | [diff] [blame] | 2932 | struct buffer_head *alloc_buffer_head(gfp_t gfp_flags) |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 2933 | { |
| 2934 | struct buffer_head *ret = kmem_cache_alloc(bh_cachep, gfp_flags); |
| 2935 | if (ret) { |
Coywolf Qi Hunt | 736c7b8 | 2005-09-06 15:18:17 -0700 | [diff] [blame] | 2936 | get_cpu_var(bh_accounting).nr++; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 2937 | recalc_bh_state(); |
Coywolf Qi Hunt | 736c7b8 | 2005-09-06 15:18:17 -0700 | [diff] [blame] | 2938 | put_cpu_var(bh_accounting); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 2939 | } |
| 2940 | return ret; |
| 2941 | } |
| 2942 | EXPORT_SYMBOL(alloc_buffer_head); |
| 2943 | |
| 2944 | void free_buffer_head(struct buffer_head *bh) |
| 2945 | { |
| 2946 | BUG_ON(!list_empty(&bh->b_assoc_buffers)); |
| 2947 | kmem_cache_free(bh_cachep, bh); |
Coywolf Qi Hunt | 736c7b8 | 2005-09-06 15:18:17 -0700 | [diff] [blame] | 2948 | get_cpu_var(bh_accounting).nr--; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 2949 | recalc_bh_state(); |
Coywolf Qi Hunt | 736c7b8 | 2005-09-06 15:18:17 -0700 | [diff] [blame] | 2950 | put_cpu_var(bh_accounting); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 2951 | } |
| 2952 | EXPORT_SYMBOL(free_buffer_head); |
| 2953 | |
| 2954 | static void |
Christoph Lameter | e18b890 | 2006-12-06 20:33:20 -0800 | [diff] [blame] | 2955 | init_buffer_head(void *data, struct kmem_cache *cachep, unsigned long flags) |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 2956 | { |
Christoph Lameter | 50953fe | 2007-05-06 14:50:16 -0700 | [diff] [blame] | 2957 | if (flags & SLAB_CTOR_CONSTRUCTOR) { |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 2958 | struct buffer_head * bh = (struct buffer_head *)data; |
| 2959 | |
| 2960 | memset(bh, 0, sizeof(*bh)); |
| 2961 | INIT_LIST_HEAD(&bh->b_assoc_buffers); |
| 2962 | } |
| 2963 | } |
| 2964 | |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 2965 | static void buffer_exit_cpu(int cpu) |
| 2966 | { |
| 2967 | int i; |
| 2968 | struct bh_lru *b = &per_cpu(bh_lrus, cpu); |
| 2969 | |
| 2970 | for (i = 0; i < BH_LRU_SIZE; i++) { |
| 2971 | brelse(b->bhs[i]); |
| 2972 | b->bhs[i] = NULL; |
| 2973 | } |
Eric Dumazet | 8a14342 | 2006-03-24 03:18:10 -0800 | [diff] [blame] | 2974 | get_cpu_var(bh_accounting).nr += per_cpu(bh_accounting, cpu).nr; |
| 2975 | per_cpu(bh_accounting, cpu).nr = 0; |
| 2976 | put_cpu_var(bh_accounting); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 2977 | } |
| 2978 | |
| 2979 | static int buffer_cpu_notify(struct notifier_block *self, |
| 2980 | unsigned long action, void *hcpu) |
| 2981 | { |
| 2982 | if (action == CPU_DEAD) |
| 2983 | buffer_exit_cpu((unsigned long)hcpu); |
| 2984 | return NOTIFY_OK; |
| 2985 | } |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 2986 | |
| 2987 | void __init buffer_init(void) |
| 2988 | { |
| 2989 | int nrpages; |
| 2990 | |
| 2991 | bh_cachep = kmem_cache_create("buffer_head", |
Paul Jackson | b019600 | 2006-03-24 03:16:09 -0800 | [diff] [blame] | 2992 | sizeof(struct buffer_head), 0, |
| 2993 | (SLAB_RECLAIM_ACCOUNT|SLAB_PANIC| |
| 2994 | SLAB_MEM_SPREAD), |
| 2995 | init_buffer_head, |
| 2996 | NULL); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 2997 | |
| 2998 | /* |
| 2999 | * Limit the bh occupancy to 10% of ZONE_NORMAL |
| 3000 | */ |
| 3001 | nrpages = (nr_free_buffer_pages() * 10) / 100; |
| 3002 | max_buffer_heads = nrpages * (PAGE_SIZE / sizeof(struct buffer_head)); |
| 3003 | hotcpu_notifier(buffer_cpu_notify, 0); |
| 3004 | } |
| 3005 | |
| 3006 | EXPORT_SYMBOL(__bforget); |
| 3007 | EXPORT_SYMBOL(__brelse); |
| 3008 | EXPORT_SYMBOL(__wait_on_buffer); |
| 3009 | EXPORT_SYMBOL(block_commit_write); |
| 3010 | EXPORT_SYMBOL(block_prepare_write); |
| 3011 | EXPORT_SYMBOL(block_read_full_page); |
| 3012 | EXPORT_SYMBOL(block_sync_page); |
| 3013 | EXPORT_SYMBOL(block_truncate_page); |
| 3014 | EXPORT_SYMBOL(block_write_full_page); |
| 3015 | EXPORT_SYMBOL(cont_prepare_write); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 3016 | EXPORT_SYMBOL(end_buffer_read_sync); |
| 3017 | EXPORT_SYMBOL(end_buffer_write_sync); |
| 3018 | EXPORT_SYMBOL(file_fsync); |
| 3019 | EXPORT_SYMBOL(fsync_bdev); |
| 3020 | EXPORT_SYMBOL(generic_block_bmap); |
| 3021 | EXPORT_SYMBOL(generic_commit_write); |
| 3022 | EXPORT_SYMBOL(generic_cont_expand); |
OGAWA Hirofumi | 05eb0b5 | 2006-01-08 01:02:13 -0800 | [diff] [blame] | 3023 | EXPORT_SYMBOL(generic_cont_expand_simple); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 3024 | EXPORT_SYMBOL(init_buffer); |
| 3025 | EXPORT_SYMBOL(invalidate_bdev); |
| 3026 | EXPORT_SYMBOL(ll_rw_block); |
| 3027 | EXPORT_SYMBOL(mark_buffer_dirty); |
| 3028 | EXPORT_SYMBOL(submit_bh); |
| 3029 | EXPORT_SYMBOL(sync_dirty_buffer); |
| 3030 | EXPORT_SYMBOL(unlock_buffer); |