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Commit 6b0310fb authored by Eric Sandeen's avatar Eric Sandeen Committed by Theodore Ts'o
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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: [<ffffffff811c6214>]
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: default avatarEric Sandeen <sandeen@redhat.com>
Signed-off-by: default avatar"Theodore Ts'o" <tytso@mit.edu>
parent 256a4535

fs/ext4/super.c

+10 −10
Original line number Original line Diff line number Diff line
@@ -241,6 +241,7 @@ handle_t *ext4_journal_start_sb(struct super_block *sb, int nblocks) 
	if (sb->s_flags & MS_RDONLY)

	if (sb->s_flags & MS_RDONLY)

		return ERR_PTR(-EROFS);

		return ERR_PTR(-EROFS);





	vfs_check_frozen(sb, SB_FREEZE_WRITE);

	/* Special case here: if the journal has aborted behind our

	/* Special case here: if the journal has aborted behind our

	 * backs (eg. EIO in the commit thread), then we still need to

	 * backs (eg. EIO in the commit thread), then we still need to

	 * take the FS itself readonly cleanly. */

	 * take the FS itself readonly cleanly. */
@@ -3485,8 +3486,10 @@ int ext4_force_commit(struct super_block *sb) 
		return 0;

		return 0;





	journal = EXT4_SB(sb)->s_journal;

	journal = EXT4_SB(sb)->s_journal;

	if (journal)

	if (journal) {

		vfs_check_frozen(sb, SB_FREEZE_WRITE);

		ret = ext4_journal_force_commit(journal);

		ret = ext4_journal_force_commit(journal);

	}





	return ret;

	return ret;

}

}
@@ -3535,18 +3538,16 @@ static int ext4_freeze(struct super_block *sb) 
	 * the journal.

	 * the journal.

	 */

	 */

	error = jbd2_journal_flush(journal);

	error = jbd2_journal_flush(journal);

	if (error < 0) {

	if (error < 0)

	out:

		goto out;

		jbd2_journal_unlock_updates(journal);

		return error;

	}





	/* Journal blocked and flushed, clear needs_recovery flag. */

	/* Journal blocked and flushed, clear needs_recovery flag. */

	EXT4_CLEAR_INCOMPAT_FEATURE(sb, EXT4_FEATURE_INCOMPAT_RECOVER);

	EXT4_CLEAR_INCOMPAT_FEATURE(sb, EXT4_FEATURE_INCOMPAT_RECOVER);

	error = ext4_commit_super(sb, 1);

	error = ext4_commit_super(sb, 1);

	if (error)

out:

		goto out;

	/* we rely on s_frozen to stop further updates */

	return 0;

	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_SET_INCOMPAT_FEATURE(sb, EXT4_FEATURE_INCOMPAT_RECOVER);

	ext4_commit_super(sb, 1);

	ext4_commit_super(sb, 1);

	unlock_super(sb);

	unlock_super(sb);

	jbd2_journal_unlock_updates(EXT4_SB(sb)->s_journal);

	return 0;

	return 0;

}

}