From 437f88cc031ffe7f37f3e705367f4fe1f4be8b0f Mon Sep 17 00:00:00 2001 From: Eric Sandeen Date: Sun, 1 Aug 2010 17:33:29 -0400 Subject: [PATCH] ext4: fix freeze deadlock under IO Commit 6b0310fbf087ad6 caused a regression resulting in deadlocks when freezing a filesystem which had active IO; the vfs_check_frozen level (SB_FREEZE_WRITE) did not let the freeze-related IO syncing through. Duh. Changing the test to FREEZE_TRANS should let the normal freeze syncing get through the fs, but still block any transactions from starting once the fs is completely frozen. I tested this by running fsstress in the background while periodically snapshotting the fs and running fsck on the result. I ran into occasional deadlocks, but different ones. I think this is a fine fix for the problem at hand, and the other deadlocky things will need more investigation. Reported-by: Phillip Susi Signed-off-by: Eric Sandeen Signed-off-by: "Theodore Ts'o" --- fs/ext4/super.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) diff --git a/fs/ext4/super.c b/fs/ext4/super.c index e046eba2478..282a2704be2 100644 --- a/fs/ext4/super.c +++ b/fs/ext4/super.c @@ -241,7 +241,7 @@ handle_t *ext4_journal_start_sb(struct super_block *sb, int nblocks) if (sb->s_flags & MS_RDONLY) return ERR_PTR(-EROFS); - vfs_check_frozen(sb, SB_FREEZE_WRITE); + vfs_check_frozen(sb, SB_FREEZE_TRANS); /* Special case here: if the journal has aborted behind our * backs (eg. EIO in the commit thread), then we still need to * take the FS itself readonly cleanly. */ @@ -3608,7 +3608,7 @@ int ext4_force_commit(struct super_block *sb) journal = EXT4_SB(sb)->s_journal; if (journal) { - vfs_check_frozen(sb, SB_FREEZE_WRITE); + vfs_check_frozen(sb, SB_FREEZE_TRANS); ret = ext4_journal_force_commit(journal); } -- 2.11.4.GIT