From: Eric Sandeen Date: Sun, 16 May 2010 06:00:00 +0000 (-0400) Subject: ext4: don't return to userspace after freezing the fs with a mutex held X-Git-Url: https://git.karo-electronics.de/?a=commitdiff_plain;h=6b0310fbf087ad6;p=linux-beck.git ext4: don't return to userspace after freezing the fs with a mutex held ext4_freeze() used jbd2_journal_lock_updates() which takes the j_barrier mutex, and then returns to userspace. The kernel does not like this: ================================================ [ BUG: lock held when returning to user space! ] ------------------------------------------------ lvcreate/1075 is leaving the kernel with locks still held! 1 lock held by lvcreate/1075: #0: (&journal->j_barrier){+.+...}, at: [] jbd2_journal_lock_updates+0xe1/0xf0 Use vfs_check_frozen() added to ext4_journal_start_sb() and ext4_force_commit() instead. Addresses-Red-Hat-Bugzilla: #568503 Signed-off-by: Eric Sandeen Signed-off-by: "Theodore Ts'o" --- diff --git a/fs/ext4/super.c b/fs/ext4/super.c index e14d22c170d5..00d09f58f188 100644 --- a/fs/ext4/super.c +++ b/fs/ext4/super.c @@ -241,6 +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); /* 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. */ @@ -3485,8 +3486,10 @@ int ext4_force_commit(struct super_block *sb) return 0; journal = EXT4_SB(sb)->s_journal; - if (journal) + if (journal) { + vfs_check_frozen(sb, SB_FREEZE_WRITE); ret = ext4_journal_force_commit(journal); + } return ret; } @@ -3535,18 +3538,16 @@ static int ext4_freeze(struct super_block *sb) * the journal. */ error = jbd2_journal_flush(journal); - if (error < 0) { - out: - jbd2_journal_unlock_updates(journal); - return error; - } + if (error < 0) + goto out; /* Journal blocked and flushed, clear needs_recovery flag. */ EXT4_CLEAR_INCOMPAT_FEATURE(sb, EXT4_FEATURE_INCOMPAT_RECOVER); error = ext4_commit_super(sb, 1); - if (error) - goto out; - return 0; +out: + /* we rely on s_frozen to stop further updates */ + jbd2_journal_unlock_updates(EXT4_SB(sb)->s_journal); + return error; } /* @@ -3563,7 +3564,6 @@ static int ext4_unfreeze(struct super_block *sb) EXT4_SET_INCOMPAT_FEATURE(sb, EXT4_FEATURE_INCOMPAT_RECOVER); ext4_commit_super(sb, 1); unlock_super(sb); - jbd2_journal_unlock_updates(EXT4_SB(sb)->s_journal); return 0; }