Zhong, Xin
2011-Apr-06 09:34 UTC
[PATCH] Btrfs: fix subvolume fake mount problem when default subvolume is set
We create two subvolumes (meego_root and meego_home) in
btrfs root directory. And set meego_root as default mount
subvolume. After we remount btrfs, meego_root is mounted
to top directory by default. Then if we create a directory with
the same name as meego_home, we can mount meego_home subvolume
sucessfully (subvol=meego_home). But this is incorrect. What we
do in this mount point will not change anything in meego_home
subvolume. The problem is when default mount subvolume is set to
meego_root, we search meego_home in meego_root. But if we find a
directory with the same name, we will treat it as subvolume. So
the solution is to check if what we find is really a subvolume.
Signed-off-by: Zhong, Xin <xin.zhong@intel.com>
---
fs/btrfs/super.c | 4 +++-
1 files changed, 3 insertions(+), 1 deletions(-)
diff --git a/fs/btrfs/super.c b/fs/btrfs/super.c
index b85fe78..66a76b7 100644
--- a/fs/btrfs/super.c
+++ b/fs/btrfs/super.c
@@ -823,7 +823,9 @@ static int btrfs_get_sb(struct file_system_type *fs_type,
int flags,
error = PTR_ERR(new_root);
goto error_free_subvol_name;
}
- if (!new_root->d_inode) {
+ if (!new_root->d_inode ||
+ /* new_root is a directory, not subvolume */
+ new_root->d_inode->i_ino != BTRFS_FIRST_FREE_OBJECTID) {
dput(root);
dput(new_root);
deactivate_locked_super(s);
--
1.7.0.4
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Goffredo Baroncelli
2011-Apr-07 05:55 UTC
Re: [PATCH] Btrfs: fix subvolume fake mount problem when default subvolume is set
Hi On 04/06/2011 11:34 AM, Zhong, Xin wrote:> We create two subvolumes (meego_root and meego_home) in > btrfs root directory. And set meego_root as default mount > subvolume. After we remount btrfs, meego_root is mounted > to top directory by default. Then if we create a directory with > the same name as meego_home, we can mount meego_home subvolume > sucessfully (subvol=meego_home). But this is incorrect. What we > do in this mount point will not change anything in meego_home > subvolume. The problem is when default mount subvolume is set to > meego_root, we search meego_home in meego_root. But if we find a > directory with the same name, we will treat it as subvolume. So > the solution is to check if what we find is really a subvolume.I think that this a bug, so a warning should be raised. We had a lot of problem because "btrfsctl -s " did the same thing: if we referred to a directory, they snapshot the directory''s subvolume and the user didn''t understood what happened. Personally I prefer that in case a wrong option the kernel raises a warning and stops, not that it makes a choice about which default is more reasonable. Reagrds G.Baroncelli> > Signed-off-by: Zhong, Xin <xin.zhong@intel.com> > --- > fs/btrfs/super.c | 4 +++- > 1 files changed, 3 insertions(+), 1 deletions(-) > > diff --git a/fs/btrfs/super.c b/fs/btrfs/super.c > index b85fe78..66a76b7 100644 > --- a/fs/btrfs/super.c > +++ b/fs/btrfs/super.c > @@ -823,7 +823,9 @@ static int btrfs_get_sb(struct file_system_type *fs_type, int flags, > error = PTR_ERR(new_root); > goto error_free_subvol_name; > } > - if (!new_root->d_inode) { > + if (!new_root->d_inode || > + /* new_root is a directory, not subvolume */ > + new_root->d_inode->i_ino != BTRFS_FIRST_FREE_OBJECTID) { > dput(root); > dput(new_root); > deactivate_locked_super(s);-- To unsubscribe from this list: send the line "unsubscribe linux-btrfs" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html