From: Josef Bacik josef@toxicpanda.com
[ Upstream commit 3ef3959b29c4a5bd65526ab310a1a18ae533172a ]
Chris Murphy reported a problem where rpm ostree will bind mount a bunch of things for whatever voodoo it's doing. But when it does this /proc/mounts shows something like
/dev/sda /mnt/test btrfs rw,relatime,subvolid=256,subvol=/foo 0 0 /dev/sda /mnt/test/baz btrfs rw,relatime,subvolid=256,subvol=/foo/bar 0 0
Despite subvolid=256 being subvol=/foo. This is because we're just spitting out the dentry of the mount point, which in the case of bind mounts is the source path for the mountpoint. Instead we should spit out the path to the actual subvol. Fix this by looking up the name for the subvolid we have mounted. With this fix the same test looks like this
/dev/sda /mnt/test btrfs rw,relatime,subvolid=256,subvol=/foo 0 0 /dev/sda /mnt/test/baz btrfs rw,relatime,subvolid=256,subvol=/foo 0 0
Reported-by: Chris Murphy chris@colorremedies.com CC: stable@vger.kernel.org # 4.4+ Signed-off-by: Josef Bacik josef@toxicpanda.com Reviewed-by: David Sterba dsterba@suse.com Signed-off-by: David Sterba dsterba@suse.com Signed-off-by: Sasha Levin sashal@kernel.org --- fs/btrfs/super.c | 10 ++++++++-- 1 file changed, 8 insertions(+), 2 deletions(-)
diff --git a/fs/btrfs/super.c b/fs/btrfs/super.c index 540e6f141745a..77e6ce0e1e351 100644 --- a/fs/btrfs/super.c +++ b/fs/btrfs/super.c @@ -1120,6 +1120,7 @@ static int btrfs_show_options(struct seq_file *seq, struct dentry *dentry) struct btrfs_fs_info *info = btrfs_sb(dentry->d_sb); struct btrfs_root *root = info->tree_root; char *compress_type; + const char *subvol_name;
if (btrfs_test_opt(root, DEGRADED)) seq_puts(seq, ",degraded"); @@ -1204,8 +1205,13 @@ static int btrfs_show_options(struct seq_file *seq, struct dentry *dentry) #endif seq_printf(seq, ",subvolid=%llu", BTRFS_I(d_inode(dentry))->root->root_key.objectid); - seq_puts(seq, ",subvol="); - seq_dentry(seq, dentry, " \t\n\"); + subvol_name = btrfs_get_subvol_name_from_objectid(info, + BTRFS_I(d_inode(dentry))->root->root_key.objectid); + if (!IS_ERR(subvol_name)) { + seq_puts(seq, ",subvol="); + seq_escape(seq, subvol_name, " \t\n\"); + kfree(subvol_name); + } return 0; }