On Sat, Jul 30, 2011 at 12:16:44AM +0800, Zhong, Xin wrote: > I believe I have submit a similar patch months ago: > http://marc.info/?l=linux-btrfs&m=130208585106572&w=2
You did! I was not aware of that. I believe adding a helper make things more clear (if it were used all over the code). > Hope it can be integrated this time, :-). mehopes too, david > > > > -----Original Message----- > > From: linux-btrfs-ow...@vger.kernel.org [mailto:linux-btrfs- > > ow...@vger.kernel.org] On Behalf Of David Sterba > > Sent: Friday, July 29, 2011 6:14 PM > > To: linux-btrfs@vger.kernel.org > > Cc: chris.ma...@oracle.com; 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 <dste...@suse.cz> > > --- > > > > 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 majord...@vger.kernel.org > > 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 majord...@vger.kernel.org > 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 majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
