diff options
Diffstat (limited to 'ANDROID_3.4.5/fs/fs-writeback.c')
| -rw-r--r-- | ANDROID_3.4.5/fs/fs-writeback.c | 1398 |
1 files changed, 0 insertions, 1398 deletions
diff --git a/ANDROID_3.4.5/fs/fs-writeback.c b/ANDROID_3.4.5/fs/fs-writeback.c deleted file mode 100644 index 42a853ee..00000000 --- a/ANDROID_3.4.5/fs/fs-writeback.c +++ /dev/null @@ -1,1398 +0,0 @@ -/* - * 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/freezer.h> -#include <linux/writeback.h> -#include <linux/blkdev.h> -#include <linux/backing-dev.h> -#include <linux/tracepoint.h> -#include "internal.h" - -/* - * 4MB minimal write chunk size - */ -#define MIN_WRITEBACK_PAGES (4096UL >> (PAGE_CACHE_SHIFT - 10)) - -/* - * 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; - enum wb_reason reason; /* why was writeback initiated? */ - - struct list_head list; /* pending work list */ - struct completion *done; /* set if the caller waits */ -}; - -/* - * We don't actually have pdflush, but this one is exported though /proc... - */ -int nr_pdflush_threads; - -/** - * writeback_in_progress - determine whether there is writeback in progress - * @bdi: the device's backing_dev_info structure. - * - * Determine whether there is writeback waiting to be handled against a - * backing device. - */ -int writeback_in_progress(struct backing_dev_info *bdi) -{ - return test_bit(BDI_writeback_running, &bdi->state); -} - -static inline struct backing_dev_info *inode_to_bdi(struct inode *inode) -{ - struct super_block *sb = inode->i_sb; - - if (strcmp(sb->s_type->name, "bdev") == 0) - return inode->i_mapping->backing_dev_info; - - return sb->s_bdi; -} - -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> - -/* Wakeup flusher thread or forker thread to fork it. Requires bdi->wb_lock. */ -static void bdi_wakeup_flusher(struct backing_dev_info *bdi) -{ - if (bdi->wb.task) { - wake_up_process(bdi->wb.task); - } else { - /* - * The bdi thread isn't there, wake up the forker thread which - * will create and run it. - */ - wake_up_process(default_backing_dev_info.wb.task); - } -} - -static void bdi_queue_work(struct backing_dev_info *bdi, - struct wb_writeback_work *work) -{ - trace_writeback_queue(bdi, work); - - spin_lock_bh(&bdi->wb_lock); - list_add_tail(&work->list, &bdi->work_list); - if (!bdi->wb.task) - trace_writeback_nothread(bdi, work); - bdi_wakeup_flusher(bdi); - spin_unlock_bh(&bdi->wb_lock); -} - -static void -__bdi_start_writeback(struct backing_dev_info *bdi, long nr_pages, - bool range_cyclic, enum wb_reason reason) -{ - struct wb_writeback_work *work; - - /* - * 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) { - if (bdi->wb.task) { - trace_writeback_nowork(bdi); - wake_up_process(bdi->wb.task); - } - return; - } - - work->sync_mode = WB_SYNC_NONE; - work->nr_pages = nr_pages; - work->range_cyclic = range_cyclic; - work->reason = reason; - - bdi_queue_work(bdi, work); -} - -/** - * bdi_start_writeback - start writeback - * @bdi: the backing device to write from - * @nr_pages: the number of pages to write - * @reason: reason why some writeback work was initiated - * - * Description: - * This does WB_SYNC_NONE opportunistic writeback. The IO is only - * started when this function returns, we make no guarantees on - * completion. Caller need not hold sb s_umount semaphore. - * - */ -void bdi_start_writeback(struct backing_dev_info *bdi, long nr_pages, - enum wb_reason reason) -{ - __bdi_start_writeback(bdi, nr_pages, true, reason); -} - -/** - * bdi_start_background_writeback - start background writeback - * @bdi: the backing device to write from - * - * Description: - * This makes sure WB_SYNC_NONE background writeback happens. When - * this function returns, it is only guaranteed that for given BDI - * some IO is happening if we are over background dirty threshold. - * Caller need not hold sb s_umount semaphore. - */ -void bdi_start_background_writeback(struct backing_dev_info *bdi) -{ - /* - * 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(bdi); - spin_lock_bh(&bdi->wb_lock); - bdi_wakeup_flusher(bdi); - spin_unlock_bh(&bdi->wb_lock); -} - -/* - * Remove the inode from the writeback list it is on. - */ -void inode_wb_list_del(struct inode *inode) -{ - struct backing_dev_info *bdi = inode_to_bdi(inode); - - spin_lock(&bdi->wb.list_lock); - list_del_init(&inode->i_wb_list); - spin_unlock(&bdi->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) -{ - assert_spin_locked(&wb->list_lock); - 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; - } - list_move(&inode->i_wb_list, &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) -{ - assert_spin_locked(&wb->list_lock); - list_move(&inode->i_wb_list, &wb->b_more_io); -} - -static void inode_sync_complete(struct inode *inode) -{ - /* - * Prevent speculative execution through - * spin_unlock(&wb->list_lock); - */ - - 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; -} - -/* - * Move expired (dirtied after 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, - struct wb_writeback_work *work) -{ - LIST_HEAD(tmp); - struct list_head *pos, *node; - struct super_block *sb = NULL; - struct inode *inode; - int do_sb_sort = 0; - int moved = 0; - - while (!list_empty(delaying_queue)) { - inode = wb_inode(delaying_queue->prev); - if (work->older_than_this && - inode_dirtied_after(inode, *work->older_than_this)) - break; - if (sb && sb != inode->i_sb) - do_sb_sort = 1; - sb = inode->i_sb; - list_move(&inode->i_wb_list, &tmp); - moved++; - } - - /* 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, work); - trace_writeback_queue_io(wb, work, moved); -} - -static int write_inode(struct inode *inode, struct writeback_control *wbc) -{ - if (inode->i_sb->s_op->write_inode && !is_bad_inode(inode)) - return inode->i_sb->s_op->write_inode(inode, wbc); - return 0; -} - -/* - * Wait for writeback on an inode to complete. - */ -static void inode_wait_for_writeback(struct inode *inode, - struct bdi_writeback *wb) -{ - 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); - spin_unlock(&wb->list_lock); - __wait_on_bit(wqh, &wq, inode_wait, TASK_UNINTERRUPTIBLE); - spin_lock(&wb->list_lock); - spin_lock(&inode->i_lock); - } -} - -/* - * Write out an inode's dirty pages. Called under wb->list_lock and - * inode->i_lock. Either the caller has an active reference on the inode or - * the inode has I_WILL_FREE set. - * - * If `wait' is set, wait on the writeout. - * - * The whole writeout design is quite complex and fragile. We want to avoid - * starvation of particular inodes when others are being redirtied, prevent - * livelocks, etc. - */ -static int -writeback_single_inode(struct inode *inode, struct bdi_writeback *wb, - struct writeback_control *wbc) -{ - struct address_space *mapping = inode->i_mapping; - long nr_to_write = wbc->nr_to_write; - unsigned dirty; - int ret; - - assert_spin_locked(&wb->list_lock); - assert_spin_locked(&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 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. - */ - if (wbc->sync_mode != WB_SYNC_ALL) { - requeue_io(inode, wb); - trace_writeback_single_inode_requeue(inode, wbc, - nr_to_write); - return 0; - } - - /* - * It's a data-integrity sync. We must wait. - */ - inode_wait_for_writeback(inode, wb); - } - - BUG_ON(inode->i_state & I_SYNC); - - /* Set I_SYNC, reset I_DIRTY_PAGES */ - inode->i_state |= I_SYNC; - inode->i_state &= ~I_DIRTY_PAGES; - spin_unlock(&inode->i_lock); - spin_unlock(&wb->list_lock); - - 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. - */ - if (wbc->sync_mode == WB_SYNC_ALL) { - 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; - inode->i_state &= ~(I_DIRTY_SYNC | I_DIRTY_DATASYNC); - spin_unlock(&inode->i_lock); - /* Don't write the inode if only I_DIRTY_PAGES was set */ - if (dirty & (I_DIRTY_SYNC | I_DIRTY_DATASYNC)) { - int err = write_inode(inode, wbc); - if (ret == 0) - ret = err; - } - - spin_lock(&wb->list_lock); - spin_lock(&inode->i_lock); - inode->i_state &= ~I_SYNC; - if (!(inode->i_state & I_FREEING)) { - /* - * 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 (mapping_tagged(mapping, PAGECACHE_TAG_DIRTY)) { - /* - * We didn't write back all the pages. nfs_writepages() - * sometimes bales out without doing anything. - */ - inode->i_state |= I_DIRTY_PAGES; - 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 { - /* - * The inode is clean. At this point we either have - * a reference to the inode or it's on it's way out. - * No need to add it back to the LRU. - */ - list_del_init(&inode->i_wb_list); - } - } - inode_sync_complete(inode); - trace_writeback_single_inode(inode, wbc, nr_to_write); - return ret; -} - -static long writeback_chunk_size(struct backing_dev_info *bdi, - 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(bdi->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. - * - * If @only_this_sb is true, then find and write all such - * inodes. Otherwise write only ones which go sequentially - * in reverse order. - * - * 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, - .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 beeing freed, first - * kind does not need peridic 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; - } - __iget(inode); - write_chunk = writeback_chunk_size(wb->bdi, work); - wbc.nr_to_write = write_chunk; - wbc.pages_skipped = 0; - - writeback_single_inode(inode, wb, &wbc); - - work->nr_pages -= write_chunk - wbc.nr_to_write; - wrote += write_chunk - wbc.nr_to_write; - if (!(inode->i_state & I_DIRTY)) - wrote++; - if (wbc.pages_skipped) { - /* - * writeback is not making progress due to locked - * buffers. Skip this inode for now. - */ - redirty_tail(inode, wb); - } - spin_unlock(&inode->i_lock); - spin_unlock(&wb->list_lock); - iput(inode); - cond_resched(); - spin_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 (!grab_super_passive(sb)) { - /* - * grab_super_passive() 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); - drop_super(sb); - - /* 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; -} - -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 backing_dev_info *bdi) -{ - 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 (bdi_stat(bdi, BDI_RECLAIMABLE) > - bdi_dirty_limit(bdi, 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) -{ - __bdi_update_bandwidth(wb->bdi, 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->bdi->work_list)) - break; - - /* - * For background writeout, stop when we are below the - * background dirty threshold - */ - if (work->for_background && !over_bground_thresh(wb->bdi)) - 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); - inode_wait_for_writeback(inode, wb); - spin_unlock(&inode->i_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 backing_dev_info *bdi) -{ - struct wb_writeback_work *work = NULL; - - spin_lock_bh(&bdi->wb_lock); - if (!list_empty(&bdi->work_list)) { - work = list_entry(bdi->work_list.next, - struct wb_writeback_work, list); - list_del_init(&work->list); - } - spin_unlock_bh(&bdi->wb_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->bdi)) { - - 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 - */ -long wb_do_writeback(struct bdi_writeback *wb, int force_wait) -{ - struct backing_dev_info *bdi = wb->bdi; - struct wb_writeback_work *work; - long wrote = 0; - - set_bit(BDI_writeback_running, &wb->bdi->state); - while ((work = get_next_work_item(bdi)) != NULL) { - /* - * Override sync mode, in case we must wait for completion - * because this thread is exiting now. - */ - if (force_wait) - work->sync_mode = WB_SYNC_ALL; - - trace_writeback_exec(bdi, work); - - wrote += wb_writeback(wb, work); - - /* - * Notify the caller of completion if this is a synchronous - * work item, otherwise just free it. - */ - if (work->done) - complete(work->done); - else - kfree(work); - } - - /* - * Check for periodic writeback, kupdated() style - */ - wrote += wb_check_old_data_flush(wb); - wrote += wb_check_background_flush(wb); - clear_bit(BDI_writeback_running, &wb->bdi->state); - - return wrote; -} - -/* - * Handle writeback of dirty data for the device backed by this bdi. Also - * wakes up periodically and does kupdated style flushing. - */ -int bdi_writeback_thread(void *data) -{ - struct bdi_writeback *wb = data; - struct backing_dev_info *bdi = wb->bdi; - long pages_written; - - current->flags |= PF_SWAPWRITE; - set_freezable(); - wb->last_active = jiffies; - - /* - * Our parent may run at a different priority, just set us to normal - */ - set_user_nice(current, 0); - - trace_writeback_thread_start(bdi); - - while (!kthread_freezable_should_stop(NULL)) { - /* - * Remove own delayed wake-up timer, since we are already awake - * and we'll take care of the preriodic write-back. - */ - del_timer(&wb->wakeup_timer); - - pages_written = wb_do_writeback(wb, 0); - - trace_writeback_pages_written(pages_written); - - if (pages_written) - wb->last_active = jiffies; - - set_current_state(TASK_INTERRUPTIBLE); - if (!list_empty(&bdi->work_list) || kthread_should_stop()) { - __set_current_state(TASK_RUNNING); - continue; - } - - if (wb_has_dirty_io(wb) && dirty_writeback_interval) - schedule_timeout(msecs_to_jiffies(dirty_writeback_interval * 10)); - else { - /* - * We have nothing to do, so can go sleep without any - * timeout and save power. When a work is queued or - * something is made dirty - we will be woken up. - */ - schedule(); - } - } - - /* Flush any work that raced with us exiting */ - if (!list_empty(&bdi->work_list)) - wb_do_writeback(wb, 1); - - trace_writeback_thread_stop(bdi); - return 0; -} - - -/* - * 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 = global_page_state(NR_FILE_DIRTY) + - global_page_state(NR_UNSTABLE_NFS); - } - - rcu_read_lock(); - list_for_each_entry_rcu(bdi, &bdi_list, bdi_list) { - if (!bdi_has_dirty_io(bdi)) - continue; - __bdi_start_writeback(bdi, nr_pages, false, reason); - } - rcu_read_unlock(); -} - -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. - */ -void __mark_inode_dirty(struct inode *inode, int flags) -{ - struct super_block *sb = inode->i_sb; - struct backing_dev_info *bdi = NULL; - - /* - * Don't do this for I_DIRTY_PAGES - that doesn't actually - * dirty the inode itself - */ - if (flags & (I_DIRTY_SYNC | I_DIRTY_DATASYNC)) { - if (sb->s_op->dirty_inode) - sb->s_op->dirty_inode(inode, flags); - } - - /* - * make sure that changes are seen by all cpus before we test i_state - * -- mikulas - */ - smp_mb(); - - /* avoid the locking if we can */ - if ((inode->i_state & flags) == flags) - return; - - if (unlikely(block_dump > 1)) - block_dump___mark_inode_dirty(inode); - - spin_lock(&inode->i_lock); - if ((inode->i_state & flags) != flags) { - const int was_dirty = inode->i_state & I_DIRTY; - - 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) { - bool wakeup_bdi = false; - bdi = inode_to_bdi(inode); - - if (bdi_cap_writeback_dirty(bdi)) { - WARN(!test_bit(BDI_registered, &bdi->state), - "bdi-%s not registered\n", bdi->name); - - /* - * 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 (!wb_has_dirty_io(&bdi->wb)) - wakeup_bdi = true; - } - - spin_unlock(&inode->i_lock); - spin_lock(&bdi->wb.list_lock); - inode->dirtied_when = jiffies; - list_move(&inode->i_wb_list, &bdi->wb.b_dirty); - spin_unlock(&bdi->wb.list_lock); - - if (wakeup_bdi) - bdi_wakeup_thread_delayed(bdi); - 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) -{ - DECLARE_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, - }; - - WARN_ON(!rwsem_is_locked(&sb->s_umount)); - bdi_queue_work(sb->s_bdi, &work); - wait_for_completion(&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); - -/** - * writeback_inodes_sb_if_idle - start writeback if none underway - * @sb: the superblock - * @reason: reason why some writeback work was initiated - * - * Invoke writeback_inodes_sb if no writeback is currently underway. - * Returns 1 if writeback was started, 0 if not. - */ -int writeback_inodes_sb_if_idle(struct super_block *sb, enum wb_reason reason) -{ - if (!writeback_in_progress(sb->s_bdi)) { - down_read(&sb->s_umount); - writeback_inodes_sb(sb, reason); - up_read(&sb->s_umount); - return 1; - } else - return 0; -} -EXPORT_SYMBOL(writeback_inodes_sb_if_idle); - -/** - * writeback_inodes_sb_nr_if_idle - start writeback if none underway - * @sb: the superblock - * @nr: the number of pages to write - * @reason: reason why some writeback work was initiated - * - * Invoke writeback_inodes_sb if no writeback is currently underway. - * Returns 1 if writeback was started, 0 if not. - */ -int writeback_inodes_sb_nr_if_idle(struct super_block *sb, - unsigned long nr, - enum wb_reason reason) -{ - if (!writeback_in_progress(sb->s_bdi)) { - down_read(&sb->s_umount); - writeback_inodes_sb_nr(sb, nr, reason); - up_read(&sb->s_umount); - return 1; - } else - return 0; -} -EXPORT_SYMBOL(writeback_inodes_sb_nr_if_idle); - -/** - * 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) -{ - DECLARE_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, - }; - - WARN_ON(!rwsem_is_locked(&sb->s_umount)); - - bdi_queue_work(sb->s_bdi, &work); - wait_for_completion(&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; - int ret; - 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(); - spin_lock(&wb->list_lock); - spin_lock(&inode->i_lock); - ret = writeback_single_inode(inode, wb, &wbc); - spin_unlock(&inode->i_lock); - spin_unlock(&wb->list_lock); - return ret; -} -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) -{ - struct bdi_writeback *wb = &inode_to_bdi(inode)->wb; - int ret; - - spin_lock(&wb->list_lock); - spin_lock(&inode->i_lock); - ret = writeback_single_inode(inode, wb, wbc); - spin_unlock(&inode->i_lock); - spin_unlock(&wb->list_lock); - return ret; -} -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); |