From edadfb10ba35da7253541e4155aa92eff758ebe6 Mon Sep 17 00:00:00 2001 From: Christoph Hellwig Date: Thu, 10 Jun 2010 12:07:54 +0200 Subject: writeback: split writeback_inodes_wb The case where we have a superblock doesn't require a loop here as we scan over all inodes in writeback_sb_inodes. Split it out into a separate helper to make the code simpler. This also allows to get rid of the sb member in struct writeback_control, which was rather out of place there. Also update the comments in writeback_sb_inodes that explain the handling of inodes from wrong superblocks. Signed-off-by: Christoph Hellwig Signed-off-by: Jens Axboe --- fs/fs-writeback.c | 82 +++++++++++++++++++++++++++++++------------------------ 1 file changed, 46 insertions(+), 36 deletions(-) (limited to 'fs/fs-writeback.c') diff --git a/fs/fs-writeback.c b/fs/fs-writeback.c index 94a602e98bb5..8cc06d5432b5 100644 --- a/fs/fs-writeback.c +++ b/fs/fs-writeback.c @@ -554,29 +554,41 @@ static bool pin_sb_for_writeback(struct super_block *sb) /* * Write a portion of b_io inodes which belong to @sb. - * If @wbc->sb != NULL, then find and write all such + * + * If @only_this_sb is true, 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) +static int writeback_sb_inodes(struct super_block *sb, struct bdi_writeback *wb, + struct writeback_control *wbc, bool only_this_sb) { while (!list_empty(&wb->b_io)) { long pages_skipped; 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 */ + + if (inode->i_sb != sb) { + if (only_this_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); + continue; + } + + /* + * The inode belongs to a different superblock. + * Bounce back to the caller to unpin this and + * pin the next superblock. + */ return 0; + } + if (inode->i_state & (I_NEW | I_WILL_FREE)) { requeue_io(inode); continue; @@ -629,29 +641,12 @@ void writeback_inodes_wb(struct bdi_writeback *wb, struct inode, i_list); struct super_block *sb = inode->i_sb; - if (wbc->sb) { - /* - * We are requested to write out inodes for a specific - * superblock. This means we already have s_umount - * taken by the caller which also waits for us to - * complete the writeout. - */ - if (sb != wbc->sb) { - redirty_tail(inode); - continue; - } - - WARN_ON(!rwsem_is_locked(&sb->s_umount)); - - ret = writeback_sb_inodes(sb, wb, wbc); - } else { - if (!pin_sb_for_writeback(sb)) { - requeue_io(inode); - continue; - } - ret = writeback_sb_inodes(sb, wb, wbc); - drop_super(sb); + if (!pin_sb_for_writeback(sb)) { + requeue_io(inode); + continue; } + ret = writeback_sb_inodes(sb, wb, wbc, false); + drop_super(sb); if (ret) break; @@ -660,6 +655,19 @@ void writeback_inodes_wb(struct bdi_writeback *wb, /* Leave any unwritten inodes on b_io */ } +static void __writeback_inodes_sb(struct super_block *sb, + struct bdi_writeback *wb, struct writeback_control *wbc) +{ + WARN_ON(!rwsem_is_locked(&sb->s_umount)); + + 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); + writeback_sb_inodes(sb, wb, wbc, true); + spin_unlock(&inode_lock); +} + /* * The maximum number of pages to writeout in a single bdi flush/kupdate * operation. We do this so we don't hold I_SYNC against an inode for @@ -698,7 +706,6 @@ static long wb_writeback(struct bdi_writeback *wb, struct wb_writeback_args *args) { struct writeback_control wbc = { - .sb = args->sb, .sync_mode = args->sync_mode, .older_than_this = NULL, .for_kupdate = args->for_kupdate, @@ -736,7 +743,10 @@ static long wb_writeback(struct bdi_writeback *wb, wbc.more_io = 0; wbc.nr_to_write = MAX_WRITEBACK_PAGES; wbc.pages_skipped = 0; - writeback_inodes_wb(wb, &wbc); + if (args->sb) + __writeback_inodes_sb(args->sb, wb, &wbc); + else + writeback_inodes_wb(wb, &wbc); args->nr_pages -= MAX_WRITEBACK_PAGES - wbc.nr_to_write; wrote += MAX_WRITEBACK_PAGES - wbc.nr_to_write; -- cgit v1.2.3