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authorOmar Sandoval <osandov@fb.com>2018-05-21 17:07:19 -0700
committerDavid Sterba <dsterba@suse.com>2018-05-28 18:24:13 +0200
commit37becec95ac31b209eb1c8e096f1093a7db00f32 (patch)
tree87dc9ed68fd8336c81d16e5edc2e3e19bcb39f28 /fs/btrfs
parentb78e2b78a88ce4982294ceb03c1227810e659a7b (diff)
Btrfs: allow empty subvol= again
I got a report that after upgrading to 4.16, someone's filesystems weren't mounting: [ 23.845852] BTRFS info (device loop0): unrecognized mount option 'subvol=' Before 4.16, this mounted the default subvolume. It turns out that this empty "subvol=" is actually an application bug, but it was causing the application to fail, so it's an ABI break if you squint. The generic parsing code we use for mount options (match_token()) doesn't match an empty string as "%s". Previously, setup_root_args() removed the "subvol=" string, but the mount path was cleaned up to not need that. Add a dummy Opt_subvol_empty to fix this. The simple workaround is to use / or . for the value of 'subvol=' . Fixes: 312c89fbca06 ("btrfs: cleanup btrfs_mount() using btrfs_mount_root()") CC: stable@vger.kernel.org # 4.16+ Signed-off-by: Omar Sandoval <osandov@fb.com> Reviewed-by: David Sterba <dsterba@suse.com> Signed-off-by: David Sterba <dsterba@suse.com>
Diffstat (limited to 'fs/btrfs')
-rw-r--r--fs/btrfs/super.c3
1 files changed, 3 insertions, 0 deletions
diff --git a/fs/btrfs/super.c b/fs/btrfs/super.c
index c67fafaa2fe7..81107ad49f3a 100644
--- a/fs/btrfs/super.c
+++ b/fs/btrfs/super.c
@@ -323,6 +323,7 @@ enum {
Opt_ssd, Opt_nossd,
Opt_ssd_spread, Opt_nossd_spread,
Opt_subvol,
+ Opt_subvol_empty,
Opt_subvolid,
Opt_thread_pool,
Opt_treelog, Opt_notreelog,
@@ -388,6 +389,7 @@ static const match_table_t tokens = {
{Opt_ssd_spread, "ssd_spread"},
{Opt_nossd_spread, "nossd_spread"},
{Opt_subvol, "subvol=%s"},
+ {Opt_subvol_empty, "subvol="},
{Opt_subvolid, "subvolid=%s"},
{Opt_thread_pool, "thread_pool=%u"},
{Opt_treelog, "treelog"},
@@ -461,6 +463,7 @@ int btrfs_parse_options(struct btrfs_fs_info *info, char *options,
btrfs_set_opt(info->mount_opt, DEGRADED);
break;
case Opt_subvol:
+ case Opt_subvol_empty:
case Opt_subvolid:
case Opt_subvolrootid:
case Opt_device: