X-Git-Url: http://ftp.safe.ca/?a=blobdiff_plain;f=fs%2Ffs-writeback.c;h=1d1088f48bc2dfe713d53a9af0fa4d51e1161428;hb=3be2264be3c00865116f997dc53ebcc90fe7fc4b;hp=f6c2155e00267724c94513af7972b2322bad9741;hpb=17bd55d037a02b04d9119511cfd1a4b985d20f63;p=safe%2Fjmp%2Flinux-2.6 diff --git a/fs/fs-writeback.c b/fs/fs-writeback.c index f6c2155..1d1088f 100644 --- a/fs/fs-writeback.c +++ b/fs/fs-writeback.c @@ -16,6 +16,7 @@ #include #include #include +#include #include #include #include @@ -41,9 +42,9 @@ struct wb_writeback_args { long nr_pages; struct super_block *sb; enum writeback_sync_modes sync_mode; - int for_kupdate:1; - int range_cyclic:1; - int for_background:1; + unsigned int for_kupdate:1; + unsigned int range_cyclic:1; + unsigned int for_background:1; }; /* @@ -242,6 +243,7 @@ static void bdi_sync_writeback(struct backing_dev_info *bdi, /** * bdi_start_writeback - start writeback * @bdi: the backing device to write from + * @sb: write inodes from this super_block * @nr_pages: the number of pages to write * * Description: @@ -380,10 +382,10 @@ static void queue_io(struct bdi_writeback *wb, unsigned long *older_than_this) move_expired_inodes(&wb->b_dirty, &wb->b_io, older_than_this); } -static int write_inode(struct inode *inode, int sync) +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, sync); + return inode->i_sb->s_op->write_inode(inode, wbc); return 0; } @@ -396,11 +398,11 @@ static void inode_wait_for_writeback(struct inode *inode) wait_queue_head_t *wqh; wqh = bit_waitqueue(&inode->i_state, __I_SYNC); - do { + while (inode->i_state & I_SYNC) { spin_unlock(&inode_lock); __wait_on_bit(wqh, &wq, inode_wait, TASK_UNINTERRUPTIBLE); spin_lock(&inode_lock); - } while (inode->i_state & I_SYNC); + } } /* @@ -420,7 +422,6 @@ static int writeback_single_inode(struct inode *inode, struct writeback_control *wbc) { struct address_space *mapping = inode->i_mapping; - int wait = wbc->sync_mode == WB_SYNC_ALL; unsigned dirty; int ret; @@ -438,7 +439,7 @@ writeback_single_inode(struct inode *inode, struct writeback_control *wbc) * We'll have another go at writing back this inode when we * completed a full scan of b_io. */ - if (!wait) { + if (wbc->sync_mode != WB_SYNC_ALL) { requeue_io(inode); return 0; } @@ -451,24 +452,36 @@ writeback_single_inode(struct inode *inode, struct writeback_control *wbc) BUG_ON(inode->i_state & I_SYNC); - /* Set I_SYNC, reset I_DIRTY */ - dirty = inode->i_state & I_DIRTY; + /* Set I_SYNC, reset I_DIRTY_PAGES */ inode->i_state |= I_SYNC; - inode->i_state &= ~I_DIRTY; - + inode->i_state &= ~I_DIRTY_PAGES; spin_unlock(&inode_lock); ret = do_writepages(mapping, wbc); - /* 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, wait); + /* + * 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; } - if (wait) { - int err = filemap_fdatawait(mapping); + /* + * Some filesystems may redirty the inode during the writeback + * due to delalloc, clear dirty metadata flags right before + * write_inode() + */ + spin_lock(&inode_lock); + dirty = inode->i_state & I_DIRTY; + inode->i_state &= ~(I_DIRTY_SYNC | I_DIRTY_DATASYNC); + spin_unlock(&inode_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; } @@ -548,108 +561,85 @@ select_queue: return ret; } -static void unpin_sb_for_writeback(struct super_block **psb) +static void unpin_sb_for_writeback(struct super_block *sb) { - struct super_block *sb = *psb; - - if (sb) { - up_read(&sb->s_umount); - put_super(sb); - *psb = NULL; - } + up_read(&sb->s_umount); + put_super(sb); } +enum sb_pin_state { + SB_PINNED, + SB_NOT_PINNED, + SB_PIN_FAILED +}; + /* * For WB_SYNC_NONE writeback, the caller does not have the sb pinned * before calling writeback. So make sure that we do pin it, so it doesn't * go away while we are writing inodes from it. - * - * Returns 0 if the super was successfully pinned (or pinning wasn't needed), - * 1 if we failed. */ -static int pin_sb_for_writeback(struct writeback_control *wbc, - struct inode *inode, struct super_block **psb) +static enum sb_pin_state pin_sb_for_writeback(struct writeback_control *wbc, + struct super_block *sb) { - struct super_block *sb = inode->i_sb; - - /* - * If this sb is already pinned, nothing more to do. If not and - * *psb is non-NULL, unpin the old one first - */ - if (sb == *psb) - return 0; - else if (*psb) - unpin_sb_for_writeback(psb); - /* * Caller must already hold the ref for this */ if (wbc->sync_mode == WB_SYNC_ALL) { WARN_ON(!rwsem_is_locked(&sb->s_umount)); - return 0; + return SB_NOT_PINNED; } - spin_lock(&sb_lock); sb->s_count++; if (down_read_trylock(&sb->s_umount)) { if (sb->s_root) { spin_unlock(&sb_lock); - goto pinned; + return SB_PINNED; } /* * umounted, drop rwsem again and fall through to failure */ up_read(&sb->s_umount); } - sb->s_count--; spin_unlock(&sb_lock); - return 1; -pinned: - *psb = sb; - return 0; + return SB_PIN_FAILED; } -static void writeback_inodes_wb(struct bdi_writeback *wb, - struct writeback_control *wbc) +/* + * Write a portion of b_io inodes which belong to @sb. + * If @wbc->sb != NULL, then find and write all such + * inodes. Otherwise write only ones which go sequentially + * in reverse order. + * Return 1, if the caller writeback routine should be + * interrupted. Otherwise return 0. + */ +static int writeback_sb_inodes(struct super_block *sb, + struct bdi_writeback *wb, + struct writeback_control *wbc) { - struct super_block *sb = wbc->sb, *pin_sb = NULL; - const unsigned long start = jiffies; /* livelock avoidance */ - - spin_lock(&inode_lock); - - if (!wbc->for_kupdate || list_empty(&wb->b_io)) - queue_io(wb, wbc->older_than_this); - while (!list_empty(&wb->b_io)) { - struct inode *inode = list_entry(wb->b_io.prev, - struct inode, i_list); long pages_skipped; - - /* - * super block given and doesn't match, skip this inode - */ - if (sb && sb != inode->i_sb) { + struct inode *inode = list_entry(wb->b_io.prev, + struct inode, i_list); + if (wbc->sb && sb != inode->i_sb) { + /* super block given and doesn't + match, skip this inode */ redirty_tail(inode); continue; } - + if (sb != inode->i_sb) + /* finish with this superblock */ + return 0; if (inode->i_state & (I_NEW | I_WILL_FREE)) { requeue_io(inode); continue; } - /* * Was this inode dirtied after sync_sb_inodes was called? * This keeps sync from extra jobs and livelock. */ - if (inode_dirtied_after(inode, start)) - break; - - if (pin_sb_for_writeback(wbc, inode, &pin_sb)) { - requeue_io(inode); - continue; - } + if (inode_dirtied_after(inode, wbc->wb_start)) + return 1; BUG_ON(inode->i_state & (I_FREEING | I_CLEAR)); __iget(inode); @@ -668,14 +658,50 @@ static void writeback_inodes_wb(struct bdi_writeback *wb, spin_lock(&inode_lock); if (wbc->nr_to_write <= 0) { wbc->more_io = 1; - break; + return 1; } if (!list_empty(&wb->b_more_io)) wbc->more_io = 1; } + /* b_io is empty */ + return 1; +} + +static void writeback_inodes_wb(struct bdi_writeback *wb, + struct writeback_control *wbc) +{ + int ret = 0; + + wbc->wb_start = jiffies; /* livelock avoidance */ + spin_lock(&inode_lock); + if (!wbc->for_kupdate || list_empty(&wb->b_io)) + queue_io(wb, wbc->older_than_this); + + while (!list_empty(&wb->b_io)) { + struct inode *inode = list_entry(wb->b_io.prev, + struct inode, i_list); + struct super_block *sb = inode->i_sb; + enum sb_pin_state state; - unpin_sb_for_writeback(&pin_sb); + if (wbc->sb && sb != wbc->sb) { + /* super block given and doesn't + match, skip this inode */ + redirty_tail(inode); + continue; + } + state = pin_sb_for_writeback(wbc, sb); + + if (state == SB_PIN_FAILED) { + requeue_io(inode); + continue; + } + ret = writeback_sb_inodes(sb, wb, wbc); + if (state == SB_PINNED) + unpin_sb_for_writeback(sb); + if (ret) + break; + } spin_unlock(&inode_lock); /* Leave any unwritten inodes on b_io */ } @@ -833,6 +859,12 @@ 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)) @@ -928,8 +960,17 @@ int bdi_writeback_task(struct bdi_writeback *wb) break; } - wait_jiffies = msecs_to_jiffies(dirty_writeback_interval * 10); - schedule_timeout_interruptible(wait_jiffies); + if (dirty_writeback_interval) { + wait_jiffies = msecs_to_jiffies(dirty_writeback_interval * 10); + schedule_timeout_interruptible(wait_jiffies); + } else { + set_current_state(TASK_INTERRUPTIBLE); + if (list_empty_careful(&wb->bdi->work_list) && + !kthread_should_stop()) + schedule(); + __set_current_state(TASK_RUNNING); + } + try_to_freeze(); }