| /* |
| * fs/fs-writeback.c |
| * |
| * Copyright (C) 2002, Linus Torvalds. |
| * |
| * Contains all the functions related to writing back and waiting |
| * upon dirty inodes against superblocks, and writing back dirty |
| * pages against inodes. ie: data writeback. Writeout of the |
| * inode itself is not handled here. |
| * |
| * 10Apr2002 Andrew Morton |
| * Split out of fs/inode.c |
| * Additions for address_space-based writeback |
| */ |
| |
| #include <linux/kernel.h> |
| #include <linux/export.h> |
| #include <linux/spinlock.h> |
| #include <linux/slab.h> |
| #include <linux/sched.h> |
| #include <linux/fs.h> |
| #include <linux/mm.h> |
| #include <linux/pagemap.h> |
| #include <linux/kthread.h> |
| #include <linux/writeback.h> |
| #include <linux/blkdev.h> |
| #include <linux/backing-dev.h> |
| #include <linux/tracepoint.h> |
| #include <linux/device.h> |
| #include "internal.h" |
| |
| /* |
| * 4MB minimal write chunk size |
| */ |
| #define MIN_WRITEBACK_PAGES (4096UL >> (PAGE_CACHE_SHIFT - 10)) |
| |
| struct wb_completion { |
| atomic_t cnt; |
| }; |
| |
| /* |
| * Passed into wb_writeback(), essentially a subset of writeback_control |
| */ |
| struct wb_writeback_work { |
| long nr_pages; |
| struct super_block *sb; |
| unsigned long *older_than_this; |
| enum writeback_sync_modes sync_mode; |
| unsigned int tagged_writepages:1; |
| unsigned int for_kupdate:1; |
| unsigned int range_cyclic:1; |
| unsigned int for_background:1; |
| unsigned int for_sync:1; /* sync(2) WB_SYNC_ALL writeback */ |
| unsigned int auto_free:1; /* free on completion */ |
| unsigned int single_wait:1; |
| unsigned int single_done:1; |
| enum wb_reason reason; /* why was writeback initiated? */ |
| |
| struct list_head list; /* pending work list */ |
| struct wb_completion *done; /* set if the caller waits */ |
| }; |
| |
| /* |
| * If one wants to wait for one or more wb_writeback_works, each work's |
| * ->done should be set to a wb_completion defined using the following |
| * macro. Once all work items are issued with wb_queue_work(), the caller |
| * can wait for the completion of all using wb_wait_for_completion(). Work |
| * items which are waited upon aren't freed automatically on completion. |
| */ |
| #define DEFINE_WB_COMPLETION_ONSTACK(cmpl) \ |
| struct wb_completion cmpl = { \ |
| .cnt = ATOMIC_INIT(1), \ |
| } |
| |
| |
| /* |
| * If an inode is constantly having its pages dirtied, but then the |
| * updates stop dirtytime_expire_interval seconds in the past, it's |
| * possible for the worst case time between when an inode has its |
| * timestamps updated and when they finally get written out to be two |
| * dirtytime_expire_intervals. We set the default to 12 hours (in |
| * seconds), which means most of the time inodes will have their |
| * timestamps written to disk after 12 hours, but in the worst case a |
| * few inodes might not their timestamps updated for 24 hours. |
| */ |
| unsigned int dirtytime_expire_interval = 12 * 60 * 60; |
| |
| static inline struct inode *wb_inode(struct list_head *head) |
| { |
| return list_entry(head, struct inode, i_wb_list); |
| } |
| |
| /* |
| * Include the creation of the trace points after defining the |
| * wb_writeback_work structure and inline functions so that the definition |
| * remains local to this file. |
| */ |
| #define CREATE_TRACE_POINTS |
| #include <trace/events/writeback.h> |
| |
| EXPORT_TRACEPOINT_SYMBOL_GPL(wbc_writepage); |
| |
| static bool wb_io_lists_populated(struct bdi_writeback *wb) |
| { |
| if (wb_has_dirty_io(wb)) { |
| return false; |
| } else { |
| set_bit(WB_has_dirty_io, &wb->state); |
| WARN_ON_ONCE(!wb->avg_write_bandwidth); |
| atomic_long_add(wb->avg_write_bandwidth, |
| &wb->bdi->tot_write_bandwidth); |
| return true; |
| } |
| } |
| |
| static void wb_io_lists_depopulated(struct bdi_writeback *wb) |
| { |
| if (wb_has_dirty_io(wb) && list_empty(&wb->b_dirty) && |
| list_empty(&wb->b_io) && list_empty(&wb->b_more_io)) { |
| clear_bit(WB_has_dirty_io, &wb->state); |
| WARN_ON_ONCE(atomic_long_sub_return(wb->avg_write_bandwidth, |
| &wb->bdi->tot_write_bandwidth) < 0); |
| } |
| } |
| |
| /** |
| * inode_wb_list_move_locked - move an inode onto a bdi_writeback IO list |
| * @inode: inode to be moved |
| * @wb: target bdi_writeback |
| * @head: one of @wb->b_{dirty|io|more_io} |
| * |
| * Move @inode->i_wb_list to @list of @wb and set %WB_has_dirty_io. |
| * Returns %true if @inode is the first occupant of the !dirty_time IO |
| * lists; otherwise, %false. |
| */ |
| static bool inode_wb_list_move_locked(struct inode *inode, |
| struct bdi_writeback *wb, |
| struct list_head *head) |
| { |
| assert_spin_locked(&wb->list_lock); |
| |
| list_move(&inode->i_wb_list, head); |
| |
| /* dirty_time doesn't count as dirty_io until expiration */ |
| if (head != &wb->b_dirty_time) |
| return wb_io_lists_populated(wb); |
| |
| wb_io_lists_depopulated(wb); |
| return false; |
| } |
| |
| /** |
| * inode_wb_list_del_locked - remove an inode from its bdi_writeback IO list |
| * @inode: inode to be removed |
| * @wb: bdi_writeback @inode is being removed from |
| * |
| * Remove @inode which may be on one of @wb->b_{dirty|io|more_io} lists and |
| * clear %WB_has_dirty_io if all are empty afterwards. |
| */ |
| static void inode_wb_list_del_locked(struct inode *inode, |
| struct bdi_writeback *wb) |
| { |
| assert_spin_locked(&wb->list_lock); |
| |
| list_del_init(&inode->i_wb_list); |
| wb_io_lists_depopulated(wb); |
| } |
| |
| static void wb_wakeup(struct bdi_writeback *wb) |
| { |
| spin_lock_bh(&wb->work_lock); |
| if (test_bit(WB_registered, &wb->state)) |
| mod_delayed_work(bdi_wq, &wb->dwork, 0); |
| spin_unlock_bh(&wb->work_lock); |
| } |
| |
| static void wb_queue_work(struct bdi_writeback *wb, |
| struct wb_writeback_work *work) |
| { |
| trace_writeback_queue(wb->bdi, work); |
| |
| spin_lock_bh(&wb->work_lock); |
| if (!test_bit(WB_registered, &wb->state)) { |
| if (work->single_wait) |
| work->single_done = 1; |
| goto out_unlock; |
| } |
| if (work->done) |
| atomic_inc(&work->done->cnt); |
| list_add_tail(&work->list, &wb->work_list); |
| mod_delayed_work(bdi_wq, &wb->dwork, 0); |
| out_unlock: |
| spin_unlock_bh(&wb->work_lock); |
| } |
| |
| /** |
| * wb_wait_for_completion - wait for completion of bdi_writeback_works |
| * @bdi: bdi work items were issued to |
| * @done: target wb_completion |
| * |
| * Wait for one or more work items issued to @bdi with their ->done field |
| * set to @done, which should have been defined with |
| * DEFINE_WB_COMPLETION_ONSTACK(). This function returns after all such |
| * work items are completed. Work items which are waited upon aren't freed |
| * automatically on completion. |
| */ |
| static void wb_wait_for_completion(struct backing_dev_info *bdi, |
| struct wb_completion *done) |
| { |
| atomic_dec(&done->cnt); /* put down the initial count */ |
| wait_event(bdi->wb_waitq, !atomic_read(&done->cnt)); |
| } |
| |
| #ifdef CONFIG_CGROUP_WRITEBACK |
| |
| /** |
| * inode_congested - test whether an inode is congested |
| * @inode: inode to test for congestion |
| * @cong_bits: mask of WB_[a]sync_congested bits to test |
| * |
| * Tests whether @inode is congested. @cong_bits is the mask of congestion |
| * bits to test and the return value is the mask of set bits. |
| * |
| * If cgroup writeback is enabled for @inode, the congestion state is |
| * determined by whether the cgwb (cgroup bdi_writeback) for the blkcg |
| * associated with @inode is congested; otherwise, the root wb's congestion |
| * state is used. |
| */ |
| int inode_congested(struct inode *inode, int cong_bits) |
| { |
| if (inode) { |
| struct bdi_writeback *wb = inode_to_wb(inode); |
| if (wb) |
| return wb_congested(wb, cong_bits); |
| } |
| |
| return wb_congested(&inode_to_bdi(inode)->wb, cong_bits); |
| } |
| EXPORT_SYMBOL_GPL(inode_congested); |
| |
| /** |
| * wb_wait_for_single_work - wait for completion of a single bdi_writeback_work |
| * @bdi: bdi the work item was issued to |
| * @work: work item to wait for |
| * |
| * Wait for the completion of @work which was issued to one of @bdi's |
| * bdi_writeback's. The caller must have set @work->single_wait before |
| * issuing it. This wait operates independently fo |
| * wb_wait_for_completion() and also disables automatic freeing of @work. |
| */ |
| static void wb_wait_for_single_work(struct backing_dev_info *bdi, |
| struct wb_writeback_work *work) |
| { |
| if (WARN_ON_ONCE(!work->single_wait)) |
| return; |
| |
| wait_event(bdi->wb_waitq, work->single_done); |
| |
| /* |
| * Paired with smp_wmb() in wb_do_writeback() and ensures that all |
| * modifications to @work prior to assertion of ->single_done is |
| * visible to the caller once this function returns. |
| */ |
| smp_rmb(); |
| } |
| |
| /** |
| * wb_split_bdi_pages - split nr_pages to write according to bandwidth |
| * @wb: target bdi_writeback to split @nr_pages to |
| * @nr_pages: number of pages to write for the whole bdi |
| * |
| * Split @wb's portion of @nr_pages according to @wb's write bandwidth in |
| * relation to the total write bandwidth of all wb's w/ dirty inodes on |
| * @wb->bdi. |
| */ |
| static long wb_split_bdi_pages(struct bdi_writeback *wb, long nr_pages) |
| { |
| unsigned long this_bw = wb->avg_write_bandwidth; |
| unsigned long tot_bw = atomic_long_read(&wb->bdi->tot_write_bandwidth); |
| |
| if (nr_pages == LONG_MAX) |
| return LONG_MAX; |
| |
| /* |
| * This may be called on clean wb's and proportional distribution |
| * may not make sense, just use the original @nr_pages in those |
| * cases. In general, we wanna err on the side of writing more. |
| */ |
| if (!tot_bw || this_bw >= tot_bw) |
| return nr_pages; |
| else |
| return DIV_ROUND_UP_ULL((u64)nr_pages * this_bw, tot_bw); |
| } |
| |
| #else /* CONFIG_CGROUP_WRITEBACK */ |
| |
| static long wb_split_bdi_pages(struct bdi_writeback *wb, long nr_pages) |
| { |
| return nr_pages; |
| } |
| |
| #endif /* CONFIG_CGROUP_WRITEBACK */ |
| |
| void wb_start_writeback(struct bdi_writeback *wb, long nr_pages, |
| bool range_cyclic, enum wb_reason reason) |
| { |
| struct wb_writeback_work *work; |
| |
| if (!wb_has_dirty_io(wb)) |
| return; |
| |
| /* |
| * This is WB_SYNC_NONE writeback, so if allocation fails just |
| * wakeup the thread for old dirty data writeback |
| */ |
| work = kzalloc(sizeof(*work), GFP_ATOMIC); |
| if (!work) { |
| trace_writeback_nowork(wb->bdi); |
| wb_wakeup(wb); |
| return; |
| } |
| |
| work->sync_mode = WB_SYNC_NONE; |
| work->nr_pages = nr_pages; |
| work->range_cyclic = range_cyclic; |
| work->reason = reason; |
| work->auto_free = 1; |
| |
| wb_queue_work(wb, work); |
| } |
| |
| /** |
| * wb_start_background_writeback - start background writeback |
| * @wb: bdi_writback to write from |
| * |
| * Description: |
| * This makes sure WB_SYNC_NONE background writeback happens. When |
| * this function returns, it is only guaranteed that for given wb |
| * some IO is happening if we are over background dirty threshold. |
| * Caller need not hold sb s_umount semaphore. |
| */ |
| void wb_start_background_writeback(struct bdi_writeback *wb) |
| { |
| /* |
| * We just wake up the flusher thread. It will perform background |
| * writeback as soon as there is no other work to do. |
| */ |
| trace_writeback_wake_background(wb->bdi); |
| wb_wakeup(wb); |
| } |
| |
| /* |
| * Remove the inode from the writeback list it is on. |
| */ |
| void inode_wb_list_del(struct inode *inode) |
| { |
| struct bdi_writeback *wb = inode_to_wb(inode); |
| |
| spin_lock(&wb->list_lock); |
| inode_wb_list_del_locked(inode, wb); |
| spin_unlock(&wb->list_lock); |
| } |
| |
| /* |
| * Redirty an inode: set its when-it-was dirtied timestamp and move it to the |
| * furthest end of its superblock's dirty-inode list. |
| * |
| * Before stamping the inode's ->dirtied_when, we check to see whether it is |
| * already the most-recently-dirtied inode on the b_dirty list. If that is |
| * the case then the inode must have been redirtied while it was being written |
| * out and we don't reset its dirtied_when. |
| */ |
| static void redirty_tail(struct inode *inode, struct bdi_writeback *wb) |
| { |
| if (!list_empty(&wb->b_dirty)) { |
| struct inode *tail; |
| |
| tail = wb_inode(wb->b_dirty.next); |
| if (time_before(inode->dirtied_when, tail->dirtied_when)) |
| inode->dirtied_when = jiffies; |
| } |
| inode_wb_list_move_locked(inode, wb, &wb->b_dirty); |
| } |
| |
| /* |
| * requeue inode for re-scanning after bdi->b_io list is exhausted. |
| */ |
| static void requeue_io(struct inode *inode, struct bdi_writeback *wb) |
| { |
| inode_wb_list_move_locked(inode, wb, &wb->b_more_io); |
| } |
| |
| static void inode_sync_complete(struct inode *inode) |
| { |
| inode->i_state &= ~I_SYNC; |
| /* If inode is clean an unused, put it into LRU now... */ |
| inode_add_lru(inode); |
| /* Waiters must see I_SYNC cleared before being woken up */ |
| smp_mb(); |
| wake_up_bit(&inode->i_state, __I_SYNC); |
| } |
| |
| static bool inode_dirtied_after(struct inode *inode, unsigned long t) |
| { |
| bool ret = time_after(inode->dirtied_when, t); |
| #ifndef CONFIG_64BIT |
| /* |
| * For inodes being constantly redirtied, dirtied_when can get stuck. |
| * It _appears_ to be in the future, but is actually in distant past. |
| * This test is necessary to prevent such wrapped-around relative times |
| * from permanently stopping the whole bdi writeback. |
| */ |
| ret = ret && time_before_eq(inode->dirtied_when, jiffies); |
| #endif |
| return ret; |
| } |
| |
| #define EXPIRE_DIRTY_ATIME 0x0001 |
| |
| /* |
| * Move expired (dirtied before work->older_than_this) dirty inodes from |
| * @delaying_queue to @dispatch_queue. |
| */ |
| static int move_expired_inodes(struct list_head *delaying_queue, |
| struct list_head *dispatch_queue, |
| int flags, |
| struct wb_writeback_work *work) |
| { |
| unsigned long *older_than_this = NULL; |
| unsigned long expire_time; |
| LIST_HEAD(tmp); |
| struct list_head *pos, *node; |
| struct super_block *sb = NULL; |
| struct inode *inode; |
| int do_sb_sort = 0; |
| int moved = 0; |
| |
| if ((flags & EXPIRE_DIRTY_ATIME) == 0) |
| older_than_this = work->older_than_this; |
| else if (!work->for_sync) { |
| expire_time = jiffies - (dirtytime_expire_interval * HZ); |
| older_than_this = &expire_time; |
| } |
| while (!list_empty(delaying_queue)) { |
| inode = wb_inode(delaying_queue->prev); |
| if (older_than_this && |
| inode_dirtied_after(inode, *older_than_this)) |
| break; |
| list_move(&inode->i_wb_list, &tmp); |
| moved++; |
| if (flags & EXPIRE_DIRTY_ATIME) |
| set_bit(__I_DIRTY_TIME_EXPIRED, &inode->i_state); |
| if (sb_is_blkdev_sb(inode->i_sb)) |
| continue; |
| if (sb && sb != inode->i_sb) |
| do_sb_sort = 1; |
| sb = inode->i_sb; |
| } |
| |
| /* just one sb in list, splice to dispatch_queue and we're done */ |
| if (!do_sb_sort) { |
| list_splice(&tmp, dispatch_queue); |
| goto out; |
| } |
| |
| /* Move inodes from one superblock together */ |
| while (!list_empty(&tmp)) { |
| sb = wb_inode(tmp.prev)->i_sb; |
| list_for_each_prev_safe(pos, node, &tmp) { |
| inode = wb_inode(pos); |
| if (inode->i_sb == sb) |
| list_move(&inode->i_wb_list, dispatch_queue); |
| } |
| } |
| out: |
| return moved; |
| } |
| |
| /* |
| * Queue all expired dirty inodes for io, eldest first. |
| * Before |
| * newly dirtied b_dirty b_io b_more_io |
| * =============> gf edc BA |
| * After |
| * newly dirtied b_dirty b_io b_more_io |
| * =============> g fBAedc |
| * | |
| * +--> dequeue for IO |
| */ |
| static void queue_io(struct bdi_writeback *wb, struct wb_writeback_work *work) |
| { |
| int moved; |
| |
| assert_spin_locked(&wb->list_lock); |
| list_splice_init(&wb->b_more_io, &wb->b_io); |
| moved = move_expired_inodes(&wb->b_dirty, &wb->b_io, 0, work); |
| moved += move_expired_inodes(&wb->b_dirty_time, &wb->b_io, |
| EXPIRE_DIRTY_ATIME, work); |
| if (moved) |
| wb_io_lists_populated(wb); |
| trace_writeback_queue_io(wb, work, moved); |
| } |
| |
| static int write_inode(struct inode *inode, struct writeback_control *wbc) |
| { |
| int ret; |
| |
| if (inode->i_sb->s_op->write_inode && !is_bad_inode(inode)) { |
| trace_writeback_write_inode_start(inode, wbc); |
| ret = inode->i_sb->s_op->write_inode(inode, wbc); |
| trace_writeback_write_inode(inode, wbc); |
| return ret; |
| } |
| return 0; |
| } |
| |
| /* |
| * Wait for writeback on an inode to complete. Called with i_lock held. |
| * Caller must make sure inode cannot go away when we drop i_lock. |
| */ |
| static void __inode_wait_for_writeback(struct inode *inode) |
| __releases(inode->i_lock) |
| __acquires(inode->i_lock) |
| { |
| DEFINE_WAIT_BIT(wq, &inode->i_state, __I_SYNC); |
| wait_queue_head_t *wqh; |
| |
| wqh = bit_waitqueue(&inode->i_state, __I_SYNC); |
| while (inode->i_state & I_SYNC) { |
| spin_unlock(&inode->i_lock); |
| __wait_on_bit(wqh, &wq, bit_wait, |
| TASK_UNINTERRUPTIBLE); |
| spin_lock(&inode->i_lock); |
| } |
| } |
| |
| /* |
| * Wait for writeback on an inode to complete. Caller must have inode pinned. |
| */ |
| void inode_wait_for_writeback(struct inode *inode) |
| { |
| spin_lock(&inode->i_lock); |
| __inode_wait_for_writeback(inode); |
| spin_unlock(&inode->i_lock); |
| } |
| |
| /* |
| * Sleep until I_SYNC is cleared. This function must be called with i_lock |
| * held and drops it. It is aimed for callers not holding any inode reference |
| * so once i_lock is dropped, inode can go away. |
| */ |
| static void inode_sleep_on_writeback(struct inode *inode) |
| __releases(inode->i_lock) |
| { |
| DEFINE_WAIT(wait); |
| wait_queue_head_t *wqh = bit_waitqueue(&inode->i_state, __I_SYNC); |
| int sleep; |
| |
| prepare_to_wait(wqh, &wait, TASK_UNINTERRUPTIBLE); |
| sleep = inode->i_state & I_SYNC; |
| spin_unlock(&inode->i_lock); |
| if (sleep) |
| schedule(); |
| finish_wait(wqh, &wait); |
| } |
| |
| /* |
| * Find proper writeback list for the inode depending on its current state and |
| * possibly also change of its state while we were doing writeback. Here we |
| * handle things such as livelock prevention or fairness of writeback among |
| * inodes. This function can be called only by flusher thread - noone else |
| * processes all inodes in writeback lists and requeueing inodes behind flusher |
| * thread's back can have unexpected consequences. |
| */ |
| static void requeue_inode(struct inode *inode, struct bdi_writeback *wb, |
| struct writeback_control *wbc) |
| { |
| if (inode->i_state & I_FREEING) |
| return; |
| |
| /* |
| * Sync livelock prevention. Each inode is tagged and synced in one |
| * shot. If still dirty, it will be redirty_tail()'ed below. Update |
| * the dirty time to prevent enqueue and sync it again. |
| */ |
| if ((inode->i_state & I_DIRTY) && |
| (wbc->sync_mode == WB_SYNC_ALL || wbc->tagged_writepages)) |
| inode->dirtied_when = jiffies; |
| |
| if (wbc->pages_skipped) { |
| /* |
| * writeback is not making progress due to locked |
| * buffers. Skip this inode for now. |
| */ |
| redirty_tail(inode, wb); |
| return; |
| } |
| |
| if (mapping_tagged(inode->i_mapping, PAGECACHE_TAG_DIRTY)) { |
| /* |
| * We didn't write back all the pages. nfs_writepages() |
| * sometimes bales out without doing anything. |
| */ |
| if (wbc->nr_to_write <= 0) { |
| /* Slice used up. Queue for next turn. */ |
| requeue_io(inode, wb); |
| } else { |
| /* |
| * Writeback blocked by something other than |
| * congestion. Delay the inode for some time to |
| * avoid spinning on the CPU (100% iowait) |
| * retrying writeback of the dirty page/inode |
| * that cannot be performed immediately. |
| */ |
| redirty_tail(inode, wb); |
| } |
| } else if (inode->i_state & I_DIRTY) { |
| /* |
| * Filesystems can dirty the inode during writeback operations, |
| * such as delayed allocation during submission or metadata |
| * updates after data IO completion. |
| */ |
| redirty_tail(inode, wb); |
| } else if (inode->i_state & I_DIRTY_TIME) { |
| inode->dirtied_when = jiffies; |
| inode_wb_list_move_locked(inode, wb, &wb->b_dirty_time); |
| } else { |
| /* The inode is clean. Remove from writeback lists. */ |
| inode_wb_list_del_locked(inode, wb); |
| } |
| } |
| |
| /* |
| * Write out an inode and its dirty pages. Do not update the writeback list |
| * linkage. That is left to the caller. The caller is also responsible for |
| * setting I_SYNC flag and calling inode_sync_complete() to clear it. |
| */ |
| static int |
| __writeback_single_inode(struct inode *inode, struct writeback_control *wbc) |
| { |
| struct address_space *mapping = inode->i_mapping; |
| long nr_to_write = wbc->nr_to_write; |
| unsigned dirty; |
| int ret; |
| |
| WARN_ON(!(inode->i_state & I_SYNC)); |
| |
| trace_writeback_single_inode_start(inode, wbc, nr_to_write); |
| |
| ret = do_writepages(mapping, wbc); |
| |
| /* |
| * Make sure to wait on the data before writing out the metadata. |
| * This is important for filesystems that modify metadata on data |
| * I/O completion. We don't do it for sync(2) writeback because it has a |
| * separate, external IO completion path and ->sync_fs for guaranteeing |
| * inode metadata is written back correctly. |
| */ |
| if (wbc->sync_mode == WB_SYNC_ALL && !wbc->for_sync) { |
| int err = filemap_fdatawait(mapping); |
| if (ret == 0) |
| ret = err; |
| } |
| |
| /* |
| * Some filesystems may redirty the inode during the writeback |
| * due to delalloc, clear dirty metadata flags right before |
| * write_inode() |
| */ |
| spin_lock(&inode->i_lock); |
| |
| dirty = inode->i_state & I_DIRTY; |
| if (inode->i_state & I_DIRTY_TIME) { |
| if ((dirty & (I_DIRTY_SYNC | I_DIRTY_DATASYNC)) || |
| unlikely(inode->i_state & I_DIRTY_TIME_EXPIRED) || |
| unlikely(time_after(jiffies, |
| (inode->dirtied_time_when + |
| dirtytime_expire_interval * HZ)))) { |
| dirty |= I_DIRTY_TIME | I_DIRTY_TIME_EXPIRED; |
| trace_writeback_lazytime(inode); |
| } |
| } else |
| inode->i_state &= ~I_DIRTY_TIME_EXPIRED; |
| inode->i_state &= ~dirty; |
| |
| /* |
| * Paired with smp_mb() in __mark_inode_dirty(). This allows |
| * __mark_inode_dirty() to test i_state without grabbing i_lock - |
| * either they see the I_DIRTY bits cleared or we see the dirtied |
| * inode. |
| * |
| * I_DIRTY_PAGES is always cleared together above even if @mapping |
| * still has dirty pages. The flag is reinstated after smp_mb() if |
| * necessary. This guarantees that either __mark_inode_dirty() |
| * sees clear I_DIRTY_PAGES or we see PAGECACHE_TAG_DIRTY. |
| */ |
| smp_mb(); |
| |
| if (mapping_tagged(mapping, PAGECACHE_TAG_DIRTY)) |
| inode->i_state |= I_DIRTY_PAGES; |
| |
| spin_unlock(&inode->i_lock); |
| |
| if (dirty & I_DIRTY_TIME) |
| mark_inode_dirty_sync(inode); |
| /* Don't write the inode if only I_DIRTY_PAGES was set */ |
| if (dirty & ~I_DIRTY_PAGES) { |
| int err = write_inode(inode, wbc); |
| if (ret == 0) |
| ret = err; |
| } |
| trace_writeback_single_inode(inode, wbc, nr_to_write); |
| return ret; |
| } |
| |
| /* |
| * Write out an inode's dirty pages. Either the caller has an active reference |
| * on the inode or the inode has I_WILL_FREE set. |
| * |
| * This function is designed to be called for writing back one inode which |
| * we go e.g. from filesystem. Flusher thread uses __writeback_single_inode() |
| * and does more profound writeback list handling in writeback_sb_inodes(). |
| */ |
| static int |
| writeback_single_inode(struct inode *inode, struct bdi_writeback *wb, |
| struct writeback_control *wbc) |
| { |
| int ret = 0; |
| |
| spin_lock(&inode->i_lock); |
| if (!atomic_read(&inode->i_count)) |
| WARN_ON(!(inode->i_state & (I_WILL_FREE|I_FREEING))); |
| else |
| WARN_ON(inode->i_state & I_WILL_FREE); |
| |
| if (inode->i_state & I_SYNC) { |
| if (wbc->sync_mode != WB_SYNC_ALL) |
| goto out; |
| /* |
| * It's a data-integrity sync. We must wait. Since callers hold |
| * inode reference or inode has I_WILL_FREE set, it cannot go |
| * away under us. |
| */ |
| __inode_wait_for_writeback(inode); |
| } |
| WARN_ON(inode->i_state & I_SYNC); |
| /* |
| * Skip inode if it is clean and we have no outstanding writeback in |
| * WB_SYNC_ALL mode. We don't want to mess with writeback lists in this |
| * function since flusher thread may be doing for example sync in |
| * parallel and if we move the inode, it could get skipped. So here we |
| * make sure inode is on some writeback list and leave it there unless |
| * we have completely cleaned the inode. |
| */ |
| if (!(inode->i_state & I_DIRTY_ALL) && |
| (wbc->sync_mode != WB_SYNC_ALL || |
| !mapping_tagged(inode->i_mapping, PAGECACHE_TAG_WRITEBACK))) |
| goto out; |
| inode->i_state |= I_SYNC; |
| spin_unlock(&inode->i_lock); |
| |
| ret = __writeback_single_inode(inode, wbc); |
| |
| spin_lock(&wb->list_lock); |
| spin_lock(&inode->i_lock); |
| /* |
| * If inode is clean, remove it from writeback lists. Otherwise don't |
| * touch it. See comment above for explanation. |
| */ |
| if (!(inode->i_state & I_DIRTY_ALL)) |
| inode_wb_list_del_locked(inode, wb); |
| spin_unlock(&wb->list_lock); |
| inode_sync_complete(inode); |
| out: |
| spin_unlock(&inode->i_lock); |
| return ret; |
| } |
| |
| static long writeback_chunk_size(struct bdi_writeback *wb, |
| struct wb_writeback_work *work) |
| { |
| long pages; |
| |
| /* |
| * WB_SYNC_ALL mode does livelock avoidance by syncing dirty |
| * inodes/pages in one big loop. Setting wbc.nr_to_write=LONG_MAX |
| * here avoids calling into writeback_inodes_wb() more than once. |
| * |
| * The intended call sequence for WB_SYNC_ALL writeback is: |
| * |
| * wb_writeback() |
| * writeback_sb_inodes() <== called only once |
| * write_cache_pages() <== called once for each inode |
| * (quickly) tag currently dirty pages |
| * (maybe slowly) sync all tagged pages |
| */ |
| if (work->sync_mode == WB_SYNC_ALL || work->tagged_writepages) |
| pages = LONG_MAX; |
| else { |
| pages = min(wb->avg_write_bandwidth / 2, |
| global_dirty_limit / DIRTY_SCOPE); |
| pages = min(pages, work->nr_pages); |
| pages = round_down(pages + MIN_WRITEBACK_PAGES, |
| MIN_WRITEBACK_PAGES); |
| } |
| |
| return pages; |
| } |
| |
| /* |
| * Write a portion of b_io inodes which belong to @sb. |
| * |
| * Return the number of pages and/or inodes written. |
| */ |
| static long writeback_sb_inodes(struct super_block *sb, |
| struct bdi_writeback *wb, |
| struct wb_writeback_work *work) |
| { |
| struct writeback_control wbc = { |
| .sync_mode = work->sync_mode, |
| .tagged_writepages = work->tagged_writepages, |
| .for_kupdate = work->for_kupdate, |
| .for_background = work->for_background, |
| .for_sync = work->for_sync, |
| .range_cyclic = work->range_cyclic, |
| .range_start = 0, |
| .range_end = LLONG_MAX, |
| }; |
| unsigned long start_time = jiffies; |
| long write_chunk; |
| long wrote = 0; /* count both pages and inodes */ |
| |
| while (!list_empty(&wb->b_io)) { |
| struct inode *inode = wb_inode(wb->b_io.prev); |
| |
| if (inode->i_sb != sb) { |
| if (work->sb) { |
| /* |
| * We only want to write back data for this |
| * superblock, move all inodes not belonging |
| * to it back onto the dirty list. |
| */ |
| redirty_tail(inode, wb); |
| continue; |
| } |
| |
| /* |
| * The inode belongs to a different superblock. |
| * Bounce back to the caller to unpin this and |
| * pin the next superblock. |
| */ |
| break; |
| } |
| |
| /* |
| * Don't bother with new inodes or inodes being freed, first |
| * kind does not need periodic writeout yet, and for the latter |
| * kind writeout is handled by the freer. |
| */ |
| spin_lock(&inode->i_lock); |
| if (inode->i_state & (I_NEW | I_FREEING | I_WILL_FREE)) { |
| spin_unlock(&inode->i_lock); |
| redirty_tail(inode, wb); |
| continue; |
| } |
| if ((inode->i_state & I_SYNC) && wbc.sync_mode != WB_SYNC_ALL) { |
| /* |
| * If this inode is locked for writeback and we are not |
| * doing writeback-for-data-integrity, move it to |
| * b_more_io so that writeback can proceed with the |
| * other inodes on s_io. |
| * |
| * We'll have another go at writing back this inode |
| * when we completed a full scan of b_io. |
| */ |
| spin_unlock(&inode->i_lock); |
| requeue_io(inode, wb); |
| trace_writeback_sb_inodes_requeue(inode); |
| continue; |
| } |
| spin_unlock(&wb->list_lock); |
| |
| /* |
| * We already requeued the inode if it had I_SYNC set and we |
| * are doing WB_SYNC_NONE writeback. So this catches only the |
| * WB_SYNC_ALL case. |
| */ |
| if (inode->i_state & I_SYNC) { |
| /* Wait for I_SYNC. This function drops i_lock... */ |
| inode_sleep_on_writeback(inode); |
| /* Inode may be gone, start again */ |
| spin_lock(&wb->list_lock); |
| continue; |
| } |
| inode->i_state |= I_SYNC; |
| spin_unlock(&inode->i_lock); |
| |
| write_chunk = writeback_chunk_size(wb, work); |
| wbc.nr_to_write = write_chunk; |
| wbc.pages_skipped = 0; |
| |
| /* |
| * We use I_SYNC to pin the inode in memory. While it is set |
| * evict_inode() will wait so the inode cannot be freed. |
| */ |
| __writeback_single_inode(inode, &wbc); |
| |
| work->nr_pages -= write_chunk - wbc.nr_to_write; |
| wrote += write_chunk - wbc.nr_to_write; |
| spin_lock(&wb->list_lock); |
| spin_lock(&inode->i_lock); |
| if (!(inode->i_state & I_DIRTY_ALL)) |
| wrote++; |
| requeue_inode(inode, wb, &wbc); |
| inode_sync_complete(inode); |
| spin_unlock(&inode->i_lock); |
| cond_resched_lock(&wb->list_lock); |
| /* |
| * bail out to wb_writeback() often enough to check |
| * background threshold and other termination conditions. |
| */ |
| if (wrote) { |
| if (time_is_before_jiffies(start_time + HZ / 10UL)) |
| break; |
| if (work->nr_pages <= 0) |
| break; |
| } |
| } |
| return wrote; |
| } |
| |
| static long __writeback_inodes_wb(struct bdi_writeback *wb, |
| struct wb_writeback_work *work) |
| { |
| unsigned long start_time = jiffies; |
| long wrote = 0; |
| |
| while (!list_empty(&wb->b_io)) { |
| struct inode *inode = wb_inode(wb->b_io.prev); |
| struct super_block *sb = inode->i_sb; |
| |
| if (!trylock_super(sb)) { |
| /* |
| * trylock_super() may fail consistently due to |
| * s_umount being grabbed by someone else. Don't use |
| * requeue_io() to avoid busy retrying the inode/sb. |
| */ |
| redirty_tail(inode, wb); |
| continue; |
| } |
| wrote += writeback_sb_inodes(sb, wb, work); |
| up_read(&sb->s_umount); |
| |
| /* refer to the same tests at the end of writeback_sb_inodes */ |
| if (wrote) { |
| if (time_is_before_jiffies(start_time + HZ / 10UL)) |
| break; |
| if (work->nr_pages <= 0) |
| break; |
| } |
| } |
| /* Leave any unwritten inodes on b_io */ |
| return wrote; |
| } |
| |
| static long writeback_inodes_wb(struct bdi_writeback *wb, long nr_pages, |
| enum wb_reason reason) |
| { |
| struct wb_writeback_work work = { |
| .nr_pages = nr_pages, |
| .sync_mode = WB_SYNC_NONE, |
| .range_cyclic = 1, |
| .reason = reason, |
| }; |
| |
| spin_lock(&wb->list_lock); |
| if (list_empty(&wb->b_io)) |
| queue_io(wb, &work); |
| __writeback_inodes_wb(wb, &work); |
| spin_unlock(&wb->list_lock); |
| |
| return nr_pages - work.nr_pages; |
| } |
| |
| static bool over_bground_thresh(struct bdi_writeback *wb) |
| { |
| unsigned long background_thresh, dirty_thresh; |
| |
| global_dirty_limits(&background_thresh, &dirty_thresh); |
| |
| if (global_page_state(NR_FILE_DIRTY) + |
| global_page_state(NR_UNSTABLE_NFS) > background_thresh) |
| return true; |
| |
| if (wb_stat(wb, WB_RECLAIMABLE) > wb_dirty_limit(wb, background_thresh)) |
| return true; |
| |
| return false; |
| } |
| |
| /* |
| * Called under wb->list_lock. If there are multiple wb per bdi, |
| * only the flusher working on the first wb should do it. |
| */ |
| static void wb_update_bandwidth(struct bdi_writeback *wb, |
| unsigned long start_time) |
| { |
| __wb_update_bandwidth(wb, 0, 0, 0, 0, 0, start_time); |
| } |
| |
| /* |
| * Explicit flushing or periodic writeback of "old" data. |
| * |
| * Define "old": the first time one of an inode's pages is dirtied, we mark the |
| * dirtying-time in the inode's address_space. So this periodic writeback code |
| * just walks the superblock inode list, writing back any inodes which are |
| * older than a specific point in time. |
| * |
| * Try to run once per dirty_writeback_interval. But if a writeback event |
| * takes longer than a dirty_writeback_interval interval, then leave a |
| * one-second gap. |
| * |
| * older_than_this takes precedence over nr_to_write. So we'll only write back |
| * all dirty pages if they are all attached to "old" mappings. |
| */ |
| static long wb_writeback(struct bdi_writeback *wb, |
| struct wb_writeback_work *work) |
| { |
| unsigned long wb_start = jiffies; |
| long nr_pages = work->nr_pages; |
| unsigned long oldest_jif; |
| struct inode *inode; |
| long progress; |
| |
| oldest_jif = jiffies; |
| work->older_than_this = &oldest_jif; |
| |
| spin_lock(&wb->list_lock); |
| for (;;) { |
| /* |
| * Stop writeback when nr_pages has been consumed |
| */ |
| if (work->nr_pages <= 0) |
| break; |
| |
| /* |
| * Background writeout and kupdate-style writeback may |
| * run forever. Stop them if there is other work to do |
| * so that e.g. sync can proceed. They'll be restarted |
| * after the other works are all done. |
| */ |
| if ((work->for_background || work->for_kupdate) && |
| !list_empty(&wb->work_list)) |
| break; |
| |
| /* |
| * For background writeout, stop when we are below the |
| * background dirty threshold |
| */ |
| if (work->for_background && !over_bground_thresh(wb)) |
| break; |
| |
| /* |
| * Kupdate and background works are special and we want to |
| * include all inodes that need writing. Livelock avoidance is |
| * handled by these works yielding to any other work so we are |
| * safe. |
| */ |
| if (work->for_kupdate) { |
| oldest_jif = jiffies - |
| msecs_to_jiffies(dirty_expire_interval * 10); |
| } else if (work->for_background) |
| oldest_jif = jiffies; |
| |
| trace_writeback_start(wb->bdi, work); |
| if (list_empty(&wb->b_io)) |
| queue_io(wb, work); |
| if (work->sb) |
| progress = writeback_sb_inodes(work->sb, wb, work); |
| else |
| progress = __writeback_inodes_wb(wb, work); |
| trace_writeback_written(wb->bdi, work); |
| |
| wb_update_bandwidth(wb, wb_start); |
| |
| /* |
| * Did we write something? Try for more |
| * |
| * Dirty inodes are moved to b_io for writeback in batches. |
| * The completion of the current batch does not necessarily |
| * mean the overall work is done. So we keep looping as long |
| * as made some progress on cleaning pages or inodes. |
| */ |
| if (progress) |
| continue; |
| /* |
| * No more inodes for IO, bail |
| */ |
| if (list_empty(&wb->b_more_io)) |
| break; |
| /* |
| * Nothing written. Wait for some inode to |
| * become available for writeback. Otherwise |
| * we'll just busyloop. |
| */ |
| if (!list_empty(&wb->b_more_io)) { |
| trace_writeback_wait(wb->bdi, work); |
| inode = wb_inode(wb->b_more_io.prev); |
| spin_lock(&inode->i_lock); |
| spin_unlock(&wb->list_lock); |
| /* This function drops i_lock... */ |
| inode_sleep_on_writeback(inode); |
| spin_lock(&wb->list_lock); |
| } |
| } |
| spin_unlock(&wb->list_lock); |
| |
| return nr_pages - work->nr_pages; |
| } |
| |
| /* |
| * Return the next wb_writeback_work struct that hasn't been processed yet. |
| */ |
| static struct wb_writeback_work *get_next_work_item(struct bdi_writeback *wb) |
| { |
| struct wb_writeback_work *work = NULL; |
| |
| spin_lock_bh(&wb->work_lock); |
| if (!list_empty(&wb->work_list)) { |
| work = list_entry(wb->work_list.next, |
| struct wb_writeback_work, list); |
| list_del_init(&work->list); |
| } |
| spin_unlock_bh(&wb->work_lock); |
| return work; |
| } |
| |
| /* |
| * Add in the number of potentially dirty inodes, because each inode |
| * write can dirty pagecache in the underlying blockdev. |
| */ |
| static unsigned long get_nr_dirty_pages(void) |
| { |
| return global_page_state(NR_FILE_DIRTY) + |
| global_page_state(NR_UNSTABLE_NFS) + |
| get_nr_dirty_inodes(); |
| } |
| |
| static long wb_check_background_flush(struct bdi_writeback *wb) |
| { |
| if (over_bground_thresh(wb)) { |
| |
| struct wb_writeback_work work = { |
| .nr_pages = LONG_MAX, |
| .sync_mode = WB_SYNC_NONE, |
| .for_background = 1, |
| .range_cyclic = 1, |
| .reason = WB_REASON_BACKGROUND, |
| }; |
| |
| return wb_writeback(wb, &work); |
| } |
| |
| return 0; |
| } |
| |
| static long wb_check_old_data_flush(struct bdi_writeback *wb) |
| { |
| unsigned long expired; |
| long nr_pages; |
| |
| /* |
| * When set to zero, disable periodic writeback |
| */ |
| if (!dirty_writeback_interval) |
| return 0; |
| |
| expired = wb->last_old_flush + |
| msecs_to_jiffies(dirty_writeback_interval * 10); |
| if (time_before(jiffies, expired)) |
| return 0; |
| |
| wb->last_old_flush = jiffies; |
| nr_pages = get_nr_dirty_pages(); |
| |
| if (nr_pages) { |
| struct wb_writeback_work work = { |
| .nr_pages = nr_pages, |
| .sync_mode = WB_SYNC_NONE, |
| .for_kupdate = 1, |
| .range_cyclic = 1, |
| .reason = WB_REASON_PERIODIC, |
| }; |
| |
| return wb_writeback(wb, &work); |
| } |
| |
| return 0; |
| } |
| |
| /* |
| * Retrieve work items and do the writeback they describe |
| */ |
| static long wb_do_writeback(struct bdi_writeback *wb) |
| { |
| struct wb_writeback_work *work; |
| long wrote = 0; |
| |
| set_bit(WB_writeback_running, &wb->state); |
| while ((work = get_next_work_item(wb)) != NULL) { |
| struct wb_completion *done = work->done; |
| bool need_wake_up = false; |
| |
| trace_writeback_exec(wb->bdi, work); |
| |
| wrote += wb_writeback(wb, work); |
| |
| if (work->single_wait) { |
| WARN_ON_ONCE(work->auto_free); |
| /* paired w/ rmb in wb_wait_for_single_work() */ |
| smp_wmb(); |
| work->single_done = 1; |
| need_wake_up = true; |
| } else if (work->auto_free) { |
| kfree(work); |
| } |
| |
| if (done && atomic_dec_and_test(&done->cnt)) |
| need_wake_up = true; |
| |
| if (need_wake_up) |
| wake_up_all(&wb->bdi->wb_waitq); |
| } |
| |
| /* |
| * Check for periodic writeback, kupdated() style |
| */ |
| wrote += wb_check_old_data_flush(wb); |
| wrote += wb_check_background_flush(wb); |
| clear_bit(WB_writeback_running, &wb->state); |
| |
| return wrote; |
| } |
| |
| /* |
| * Handle writeback of dirty data for the device backed by this bdi. Also |
| * reschedules periodically and does kupdated style flushing. |
| */ |
| void wb_workfn(struct work_struct *work) |
| { |
| struct bdi_writeback *wb = container_of(to_delayed_work(work), |
| struct bdi_writeback, dwork); |
| long pages_written; |
| |
| set_worker_desc("flush-%s", dev_name(wb->bdi->dev)); |
| current->flags |= PF_SWAPWRITE; |
| |
| if (likely(!current_is_workqueue_rescuer() || |
| !test_bit(WB_registered, &wb->state))) { |
| /* |
| * The normal path. Keep writing back @wb until its |
| * work_list is empty. Note that this path is also taken |
| * if @wb is shutting down even when we're running off the |
| * rescuer as work_list needs to be drained. |
| */ |
| do { |
| pages_written = wb_do_writeback(wb); |
| trace_writeback_pages_written(pages_written); |
| } while (!list_empty(&wb->work_list)); |
| } else { |
| /* |
| * bdi_wq can't get enough workers and we're running off |
| * the emergency worker. Don't hog it. Hopefully, 1024 is |
| * enough for efficient IO. |
| */ |
| pages_written = writeback_inodes_wb(wb, 1024, |
| WB_REASON_FORKER_THREAD); |
| trace_writeback_pages_written(pages_written); |
| } |
| |
| if (!list_empty(&wb->work_list)) |
| mod_delayed_work(bdi_wq, &wb->dwork, 0); |
| else if (wb_has_dirty_io(wb) && dirty_writeback_interval) |
| wb_wakeup_delayed(wb); |
| |
| current->flags &= ~PF_SWAPWRITE; |
| } |
| |
| /* |
| * Start writeback of `nr_pages' pages. If `nr_pages' is zero, write back |
| * the whole world. |
| */ |
| void wakeup_flusher_threads(long nr_pages, enum wb_reason reason) |
| { |
| struct backing_dev_info *bdi; |
| |
| if (!nr_pages) |
| nr_pages = get_nr_dirty_pages(); |
| |
| rcu_read_lock(); |
| list_for_each_entry_rcu(bdi, &bdi_list, bdi_list) { |
| struct bdi_writeback *wb; |
| struct wb_iter iter; |
| |
| if (!bdi_has_dirty_io(bdi)) |
| continue; |
| |
| bdi_for_each_wb(wb, bdi, &iter, 0) |
| wb_start_writeback(wb, wb_split_bdi_pages(wb, nr_pages), |
| false, reason); |
| } |
| rcu_read_unlock(); |
| } |
| |
| /* |
| * Wake up bdi's periodically to make sure dirtytime inodes gets |
| * written back periodically. We deliberately do *not* check the |
| * b_dirtytime list in wb_has_dirty_io(), since this would cause the |
| * kernel to be constantly waking up once there are any dirtytime |
| * inodes on the system. So instead we define a separate delayed work |
| * function which gets called much more rarely. (By default, only |
| * once every 12 hours.) |
| * |
| * If there is any other write activity going on in the file system, |
| * this function won't be necessary. But if the only thing that has |
| * happened on the file system is a dirtytime inode caused by an atime |
| * update, we need this infrastructure below to make sure that inode |
| * eventually gets pushed out to disk. |
| */ |
| static void wakeup_dirtytime_writeback(struct work_struct *w); |
| static DECLARE_DELAYED_WORK(dirtytime_work, wakeup_dirtytime_writeback); |
| |
| static void wakeup_dirtytime_writeback(struct work_struct *w) |
| { |
| struct backing_dev_info *bdi; |
| |
| rcu_read_lock(); |
| list_for_each_entry_rcu(bdi, &bdi_list, bdi_list) { |
| struct bdi_writeback *wb; |
| struct wb_iter iter; |
| |
| bdi_for_each_wb(wb, bdi, &iter, 0) |
| if (!list_empty(&bdi->wb.b_dirty_time)) |
| wb_wakeup(&bdi->wb); |
| } |
| rcu_read_unlock(); |
| schedule_delayed_work(&dirtytime_work, dirtytime_expire_interval * HZ); |
| } |
| |
| static int __init start_dirtytime_writeback(void) |
| { |
| schedule_delayed_work(&dirtytime_work, dirtytime_expire_interval * HZ); |
| return 0; |
| } |
| __initcall(start_dirtytime_writeback); |
| |
| int dirtytime_interval_handler(struct ctl_table *table, int write, |
| void __user *buffer, size_t *lenp, loff_t *ppos) |
| { |
| int ret; |
| |
| ret = proc_dointvec_minmax(table, write, buffer, lenp, ppos); |
| if (ret == 0 && write) |
| mod_delayed_work(system_wq, &dirtytime_work, 0); |
| return ret; |
| } |
| |
| static noinline void block_dump___mark_inode_dirty(struct inode *inode) |
| { |
| if (inode->i_ino || strcmp(inode->i_sb->s_id, "bdev")) { |
| struct dentry *dentry; |
| const char *name = "?"; |
| |
| dentry = d_find_alias(inode); |
| if (dentry) { |
| spin_lock(&dentry->d_lock); |
| name = (const char *) dentry->d_name.name; |
| } |
| printk(KERN_DEBUG |
| "%s(%d): dirtied inode %lu (%s) on %s\n", |
| current->comm, task_pid_nr(current), inode->i_ino, |
| name, inode->i_sb->s_id); |
| if (dentry) { |
| spin_unlock(&dentry->d_lock); |
| dput(dentry); |
| } |
| } |
| } |
| |
| /** |
| * __mark_inode_dirty - internal function |
| * @inode: inode to mark |
| * @flags: what kind of dirty (i.e. I_DIRTY_SYNC) |
| * Mark an inode as dirty. Callers should use mark_inode_dirty or |
| * mark_inode_dirty_sync. |
| * |
| * Put the inode on the super block's dirty list. |
| * |
| * CAREFUL! We mark it dirty unconditionally, but move it onto the |
| * dirty list only if it is hashed or if it refers to a blockdev. |
| * If it was not hashed, it will never be added to the dirty list |
| * even if it is later hashed, as it will have been marked dirty already. |
| * |
| * In short, make sure you hash any inodes _before_ you start marking |
| * them dirty. |
| * |
| * Note that for blockdevs, inode->dirtied_when represents the dirtying time of |
| * the block-special inode (/dev/hda1) itself. And the ->dirtied_when field of |
| * the kernel-internal blockdev inode represents the dirtying time of the |
| * blockdev's pages. This is why for I_DIRTY_PAGES we always use |
| * page->mapping->host, so the page-dirtying time is recorded in the internal |
| * blockdev inode. |
| */ |
| #define I_DIRTY_INODE (I_DIRTY_SYNC | I_DIRTY_DATASYNC) |
| void __mark_inode_dirty(struct inode *inode, int flags) |
| { |
| struct super_block *sb = inode->i_sb; |
| struct backing_dev_info *bdi = NULL; |
| int dirtytime; |
| |
| trace_writeback_mark_inode_dirty(inode, flags); |
| |
| /* |
| * Don't do this for I_DIRTY_PAGES - that doesn't actually |
| * dirty the inode itself |
| */ |
| if (flags & (I_DIRTY_SYNC | I_DIRTY_DATASYNC | I_DIRTY_TIME)) { |
| trace_writeback_dirty_inode_start(inode, flags); |
| |
| if (sb->s_op->dirty_inode) |
| sb->s_op->dirty_inode(inode, flags); |
| |
| trace_writeback_dirty_inode(inode, flags); |
| } |
| if (flags & I_DIRTY_INODE) |
| flags &= ~I_DIRTY_TIME; |
| dirtytime = flags & I_DIRTY_TIME; |
| |
| /* |
| * Paired with smp_mb() in __writeback_single_inode() for the |
| * following lockless i_state test. See there for details. |
| */ |
| smp_mb(); |
| |
| if (((inode->i_state & flags) == flags) || |
| (dirtytime && (inode->i_state & I_DIRTY_INODE))) |
| return; |
| |
| if (unlikely(block_dump)) |
| block_dump___mark_inode_dirty(inode); |
| |
| spin_lock(&inode->i_lock); |
| if (dirtytime && (inode->i_state & I_DIRTY_INODE)) |
| goto out_unlock_inode; |
| if ((inode->i_state & flags) != flags) { |
| const int was_dirty = inode->i_state & I_DIRTY; |
| |
| inode_attach_wb(inode, NULL); |
| |
| if (flags & I_DIRTY_INODE) |
| inode->i_state &= ~I_DIRTY_TIME; |
| inode->i_state |= flags; |
| |
| /* |
| * If the inode is being synced, just update its dirty state. |
| * The unlocker will place the inode on the appropriate |
| * superblock list, based upon its state. |
| */ |
| if (inode->i_state & I_SYNC) |
| goto out_unlock_inode; |
| |
| /* |
| * Only add valid (hashed) inodes to the superblock's |
| * dirty list. Add blockdev inodes as well. |
| */ |
| if (!S_ISBLK(inode->i_mode)) { |
| if (inode_unhashed(inode)) |
| goto out_unlock_inode; |
| } |
| if (inode->i_state & I_FREEING) |
| goto out_unlock_inode; |
| |
| /* |
| * If the inode was already on b_dirty/b_io/b_more_io, don't |
| * reposition it (that would break b_dirty time-ordering). |
| */ |
| if (!was_dirty) { |
| struct list_head *dirty_list; |
| bool wakeup_bdi = false; |
| bdi = inode_to_bdi(inode); |
| |
| spin_unlock(&inode->i_lock); |
| spin_lock(&bdi->wb.list_lock); |
| |
| WARN(bdi_cap_writeback_dirty(bdi) && |
| !test_bit(WB_registered, &bdi->wb.state), |
| "bdi-%s not registered\n", bdi->name); |
| |
| inode->dirtied_when = jiffies; |
| if (dirtytime) |
| inode->dirtied_time_when = jiffies; |
| |
| if (inode->i_state & (I_DIRTY_INODE | I_DIRTY_PAGES)) |
| dirty_list = &bdi->wb.b_dirty; |
| else |
| dirty_list = &bdi->wb.b_dirty_time; |
| |
| wakeup_bdi = inode_wb_list_move_locked(inode, &bdi->wb, |
| dirty_list); |
| |
| spin_unlock(&bdi->wb.list_lock); |
| trace_writeback_dirty_inode_enqueue(inode); |
| |
| /* |
| * If this is the first dirty inode for this bdi, |
| * we have to wake-up the corresponding bdi thread |
| * to make sure background write-back happens |
| * later. |
| */ |
| if (bdi_cap_writeback_dirty(bdi) && wakeup_bdi) |
| wb_wakeup_delayed(&bdi->wb); |
| return; |
| } |
| } |
| out_unlock_inode: |
| spin_unlock(&inode->i_lock); |
| |
| } |
| EXPORT_SYMBOL(__mark_inode_dirty); |
| |
| static void wait_sb_inodes(struct super_block *sb) |
| { |
| struct inode *inode, *old_inode = NULL; |
| |
| /* |
| * We need to be protected against the filesystem going from |
| * r/o to r/w or vice versa. |
| */ |
| WARN_ON(!rwsem_is_locked(&sb->s_umount)); |
| |
| spin_lock(&inode_sb_list_lock); |
| |
| /* |
| * Data integrity sync. Must wait for all pages under writeback, |
| * because there may have been pages dirtied before our sync |
| * call, but which had writeout started before we write it out. |
| * In which case, the inode may not be on the dirty list, but |
| * we still have to wait for that writeout. |
| */ |
| list_for_each_entry(inode, &sb->s_inodes, i_sb_list) { |
| struct address_space *mapping = inode->i_mapping; |
| |
| spin_lock(&inode->i_lock); |
| if ((inode->i_state & (I_FREEING|I_WILL_FREE|I_NEW)) || |
| (mapping->nrpages == 0)) { |
| spin_unlock(&inode->i_lock); |
| continue; |
| } |
| __iget(inode); |
| spin_unlock(&inode->i_lock); |
| spin_unlock(&inode_sb_list_lock); |
| |
| /* |
| * We hold a reference to 'inode' so it couldn't have been |
| * removed from s_inodes list while we dropped the |
| * inode_sb_list_lock. We cannot iput the inode now as we can |
| * be holding the last reference and we cannot iput it under |
| * inode_sb_list_lock. So we keep the reference and iput it |
| * later. |
| */ |
| iput(old_inode); |
| old_inode = inode; |
| |
| filemap_fdatawait(mapping); |
| |
| cond_resched(); |
| |
| spin_lock(&inode_sb_list_lock); |
| } |
| spin_unlock(&inode_sb_list_lock); |
| iput(old_inode); |
| } |
| |
| /** |
| * writeback_inodes_sb_nr - writeback dirty inodes from given super_block |
| * @sb: the superblock |
| * @nr: the number of pages to write |
| * @reason: reason why some writeback work initiated |
| * |
| * Start writeback on some inodes on this super_block. No guarantees are made |
| * on how many (if any) will be written, and this function does not wait |
| * for IO completion of submitted IO. |
| */ |
| void writeback_inodes_sb_nr(struct super_block *sb, |
| unsigned long nr, |
| enum wb_reason reason) |
| { |
| DEFINE_WB_COMPLETION_ONSTACK(done); |
| struct wb_writeback_work work = { |
| .sb = sb, |
| .sync_mode = WB_SYNC_NONE, |
| .tagged_writepages = 1, |
| .done = &done, |
| .nr_pages = nr, |
| .reason = reason, |
| }; |
| struct backing_dev_info *bdi = sb->s_bdi; |
| |
| if (!bdi_has_dirty_io(bdi) || bdi == &noop_backing_dev_info) |
| return; |
| WARN_ON(!rwsem_is_locked(&sb->s_umount)); |
| wb_queue_work(&bdi->wb, &work); |
| wb_wait_for_completion(bdi, &done); |
| } |
| EXPORT_SYMBOL(writeback_inodes_sb_nr); |
| |
| /** |
| * writeback_inodes_sb - writeback dirty inodes from given super_block |
| * @sb: the superblock |
| * @reason: reason why some writeback work was initiated |
| * |
| * Start writeback on some inodes on this super_block. No guarantees are made |
| * on how many (if any) will be written, and this function does not wait |
| * for IO completion of submitted IO. |
| */ |
| void writeback_inodes_sb(struct super_block *sb, enum wb_reason reason) |
| { |
| return writeback_inodes_sb_nr(sb, get_nr_dirty_pages(), reason); |
| } |
| EXPORT_SYMBOL(writeback_inodes_sb); |
| |
| /** |
| * try_to_writeback_inodes_sb_nr - try to start writeback if none underway |
| * @sb: the superblock |
| * @nr: the number of pages to write |
| * @reason: the reason of writeback |
| * |
| * Invoke writeback_inodes_sb_nr if no writeback is currently underway. |
| * Returns 1 if writeback was started, 0 if not. |
| */ |
| int try_to_writeback_inodes_sb_nr(struct super_block *sb, |
| unsigned long nr, |
| enum wb_reason reason) |
| { |
| if (writeback_in_progress(&sb->s_bdi->wb)) |
| return 1; |
| |
| if (!down_read_trylock(&sb->s_umount)) |
| return 0; |
| |
| writeback_inodes_sb_nr(sb, nr, reason); |
| up_read(&sb->s_umount); |
| return 1; |
| } |
| EXPORT_SYMBOL(try_to_writeback_inodes_sb_nr); |
| |
| /** |
| * try_to_writeback_inodes_sb - try to start writeback if none underway |
| * @sb: the superblock |
| * @reason: reason why some writeback work was initiated |
| * |
| * Implement by try_to_writeback_inodes_sb_nr() |
| * Returns 1 if writeback was started, 0 if not. |
| */ |
| int try_to_writeback_inodes_sb(struct super_block *sb, enum wb_reason reason) |
| { |
| return try_to_writeback_inodes_sb_nr(sb, get_nr_dirty_pages(), reason); |
| } |
| EXPORT_SYMBOL(try_to_writeback_inodes_sb); |
| |
| /** |
| * sync_inodes_sb - sync sb inode pages |
| * @sb: the superblock |
| * |
| * This function writes and waits on any dirty inode belonging to this |
| * super_block. |
| */ |
| void sync_inodes_sb(struct super_block *sb) |
| { |
| DEFINE_WB_COMPLETION_ONSTACK(done); |
| struct wb_writeback_work work = { |
| .sb = sb, |
| .sync_mode = WB_SYNC_ALL, |
| .nr_pages = LONG_MAX, |
| .range_cyclic = 0, |
| .done = &done, |
| .reason = WB_REASON_SYNC, |
| .for_sync = 1, |
| }; |
| struct backing_dev_info *bdi = sb->s_bdi; |
| |
| /* Nothing to do? */ |
| if (!bdi_has_dirty_io(bdi) || bdi == &noop_backing_dev_info) |
| return; |
| WARN_ON(!rwsem_is_locked(&sb->s_umount)); |
| |
| wb_queue_work(&bdi->wb, &work); |
| wb_wait_for_completion(bdi, &done); |
| |
| wait_sb_inodes(sb); |
| } |
| EXPORT_SYMBOL(sync_inodes_sb); |
| |
| /** |
| * write_inode_now - write an inode to disk |
| * @inode: inode to write to disk |
| * @sync: whether the write should be synchronous or not |
| * |
| * This function commits an inode to disk immediately if it is dirty. This is |
| * primarily needed by knfsd. |
| * |
| * The caller must either have a ref on the inode or must have set I_WILL_FREE. |
| */ |
| int write_inode_now(struct inode *inode, int sync) |
| { |
| struct bdi_writeback *wb = &inode_to_bdi(inode)->wb; |
| struct writeback_control wbc = { |
| .nr_to_write = LONG_MAX, |
| .sync_mode = sync ? WB_SYNC_ALL : WB_SYNC_NONE, |
| .range_start = 0, |
| .range_end = LLONG_MAX, |
| }; |
| |
| if (!mapping_cap_writeback_dirty(inode->i_mapping)) |
| wbc.nr_to_write = 0; |
| |
| might_sleep(); |
| return writeback_single_inode(inode, wb, &wbc); |
| } |
| EXPORT_SYMBOL(write_inode_now); |
| |
| /** |
| * sync_inode - write an inode and its pages to disk. |
| * @inode: the inode to sync |
| * @wbc: controls the writeback mode |
| * |
| * sync_inode() will write an inode and its pages to disk. It will also |
| * correctly update the inode on its superblock's dirty inode lists and will |
| * update inode->i_state. |
| * |
| * The caller must have a ref on the inode. |
| */ |
| int sync_inode(struct inode *inode, struct writeback_control *wbc) |
| { |
| return writeback_single_inode(inode, &inode_to_bdi(inode)->wb, wbc); |
| } |
| EXPORT_SYMBOL(sync_inode); |
| |
| /** |
| * sync_inode_metadata - write an inode to disk |
| * @inode: the inode to sync |
| * @wait: wait for I/O to complete. |
| * |
| * Write an inode to disk and adjust its dirty state after completion. |
| * |
| * Note: only writes the actual inode, no associated data or other metadata. |
| */ |
| int sync_inode_metadata(struct inode *inode, int wait) |
| { |
| struct writeback_control wbc = { |
| .sync_mode = wait ? WB_SYNC_ALL : WB_SYNC_NONE, |
| .nr_to_write = 0, /* metadata-only */ |
| }; |
| |
| return sync_inode(inode, &wbc); |
| } |
| EXPORT_SYMBOL(sync_inode_metadata); |