On Thu, Apr 09, 2015 at 02:34:51PM -0700, Omar Sandoval wrote: > Since commit 0723a0473fb4 ("btrfs: allow mounting btrfs subvolumes with > different ro/rw options"), when mounting a subvolume read/write when > another subvolume has previously been mounted read-only, we first do a > remount. However, this should be done with the superblock locked, as per > sync_filesystem(): > > /* > * We need to be protected against the filesystem going from > * r/o to r/w or vice versa. > */ > WARN_ON(!rwsem_is_locked(&sb->s_umount)); > > This WARN_ON can easily be hit with: > > mkfs.btrfs -f /dev/vdb > mount /dev/vdb /mnt > btrfs subvol create /mnt/vol1 > btrfs subvol create /mnt/vol2 > umount /mnt > mount -oro,subvol=/vol1 /dev/vdb /mnt > mount -orw,subvol=/vol2 /dev/vdb /mnt2 > > Fixes: 0723a0473fb4 ("btrfs: allow mounting btrfs subvolumes with different > ro/rw options") > Signed-off-by: Omar Sandoval <osan...@osandov.com>
Reviewed-by: David Sterba <dste...@suse.cz> -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/