From d19de7edf59cdd586777b009e0e8fbe5412dd35f Mon Sep 17 00:00:00 2001 From: Christoph Hellwig Date: Tue, 8 Jun 2010 18:14:58 +0200 Subject: [PATCH] writeback: fix writeback_inodes_wb from writeback_inodes_sb When we call writeback_inodes_wb from writeback_inodes_sb we always have s_umount held, which currently makes the whole operation a no-op. But if we are called to write out inodes for a specific superblock we always have s_umount held, so replace the incorrect logic checking for WB_SYNC_ALL which only worked by coincidence with the proper check for an explicit superblock argument. Signed-off-by: Christoph Hellwig Signed-off-by: Jens Axboe --- fs/fs-writeback.c | 61 ++++++++++++++++++----------------------------- 1 file changed, 23 insertions(+), 38 deletions(-) diff --git a/fs/fs-writeback.c b/fs/fs-writeback.c index 2627f0dfcd9c..68ece4b18916 100644 --- a/fs/fs-writeback.c +++ b/fs/fs-writeback.c @@ -518,39 +518,19 @@ select_queue: return ret; } -static void unpin_sb_for_writeback(struct super_block *sb) -{ - 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 + * For background 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. */ -static enum sb_pin_state pin_sb_for_writeback(struct writeback_control *wbc, - struct super_block *sb) +static bool pin_sb_for_writeback(struct super_block *sb) { - /* - * Caller must already hold the ref for this - */ - if (wbc->sync_mode == WB_SYNC_ALL) { - WARN_ON(!rwsem_is_locked(&sb->s_umount)); - 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); - return SB_PINNED; + return true; } /* * umounted, drop rwsem again and fall through to failure @@ -559,7 +539,7 @@ static enum sb_pin_state pin_sb_for_writeback(struct writeback_control *wbc, } sb->s_count--; spin_unlock(&sb_lock); - return SB_PIN_FAILED; + return false; } /* @@ -638,24 +618,29 @@ static void writeback_inodes_wb(struct bdi_writeback *wb, 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; - 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 (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; + } - if (state == SB_PIN_FAILED) { - requeue_io(inode); - continue; + WARN_ON(!rwsem_is_locked(&sb->s_umount)); + + ret = writeback_sb_inodes(sb, wb, wbc); + } else { + if (!pin_sb_for_writeback(sb)) + continue; + ret = writeback_sb_inodes(sb, wb, wbc); + drop_super(sb); } - ret = writeback_sb_inodes(sb, wb, wbc); - if (state == SB_PINNED) - unpin_sb_for_writeback(sb); if (ret) break; } -- 2.20.1