I believe I have submit a similar patch months ago: http://marc.info/?l=linux-btrfs&m=130208585106572&w=2 Hope it can be integrated this time, :-). > -----Original Message----- > From: linux-btrfs-owner@xxxxxxxxxxxxxxx [mailto:linux-btrfs- > owner@xxxxxxxxxxxxxxx] On Behalf Of David Sterba > Sent: Friday, July 29, 2011 6:14 PM > To: linux-btrfs@xxxxxxxxxxxxxxx > Cc: chris.mason@xxxxxxxxxx; David Sterba > Subject: [PATCH] btrfs: do not allow mounting non-subvolumes via subvol > option > > There's a missing test whether the path passed to subvol=path option > during mount is a real subvolume, allowing any directory located in > default subovlume to be passed and accepted for mount. > > (current btrfs progs prevent this early) > $ btrfs subvol snapshot . p1-snap > ERROR: '.' is not a subvolume > > (with "is subvolume?" test bypassed) > $ btrfs subvol snapshot . p1-snap > Create a snapshot of '.' in './p1-snap' > > $ btrfs subvol list -p . > ID 258 parent 5 top level 5 path subvol > ID 259 parent 5 top level 5 path subvol1 > ID 260 parent 5 top level 5 path default-subvol1 > ID 262 parent 5 top level 5 path p1/p1-snapshot > ID 263 parent 259 top level 5 path subvol1/subvol1-snap > > The problem I see is that this makes a false impression of snapshotting > the > given subvolume but in fact snapshots the default one: a user expects > outcome > like ID 263 but in fact gets ID 262 . > > This patch makes mount fail with EINVAL with a message in syslog. > > Signed-off-by: David Sterba <dsterba@xxxxxxx> > --- > > I did not find a better errno than EINVAL, probably adding someting > like > ENSUBVOL would be better so that other filesystems with such > functionality may > use it in future. > > fs/btrfs/super.c | 19 +++++++++++++++++++ > 1 files changed, 19 insertions(+), 0 deletions(-) > > diff --git a/fs/btrfs/super.c b/fs/btrfs/super.c > index 15634d4..0c2a1d1 100644 > --- a/fs/btrfs/super.c > +++ b/fs/btrfs/super.c > @@ -753,6 +753,15 @@ static int btrfs_set_super(struct super_block *s, > void *data) > return set_anon_super(s, data); > } > > +/* > + * subvolumes are identified by ino 256 > + */ > +static inline int is_subvolume_inode(struct inode *inode) > +{ > + if (inode && inode->i_ino == BTRFS_FIRST_FREE_OBJECTID) > + return 1; > + return 0; > +} > > /* > * Find a superblock for the given device / mount point. > @@ -873,6 +882,16 @@ static struct dentry *btrfs_mount(struct > file_system_type *fs_type, int flags, > error = -ENXIO; > goto error_free_subvol_name; > } > + > + if (!is_subvolume_inode(new_root->d_inode)) { > + dput(root); > + dput(new_root); > + deactivate_locked_super(s); > + error = -EINVAL; > + printk(KERN_ERR "btrfs: '%s' is not a valid > subvolume\n", > + subvol_name); > + goto error_free_subvol_name; > + } > dput(root); > root = new_root; > } else { > -- > 1.7.6 > > -- > To unsubscribe from this list: send the line "unsubscribe linux-btrfs" > in > the body of a message to majordomo@xxxxxxxxxxxxxxx > More majordomo info at http://vger.kernel.org/majordomo-info.html -- To unsubscribe from this list: send the line "unsubscribe linux-btrfs" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
