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Btrfs: fail on mismatched subvol and subvolid mount options

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There's nothing to stop a user from passing both subvol= and subvolid=
to mount, but if they don't refer to the same subvolume, someone is
going to be surprised at some point. Error out on this case, but allow
users to pass in both if they do match (which they could, for example,
get out of /proc/mounts).

Reviewed-by: David Sterba <dsterba@suse.cz>
Signed-off-by: Omar Sandoval <osandov@osandov.com>
Signed-off-by: Chris Mason <clm@fb.com>
This commit is contained in:
Omar Sandoval 2015-05-18 02:16:29 -07:00 committed by Chris Mason
parent fa33065950
commit bb289b7be6
1 changed files with 25 additions and 8 deletions
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33
fs/btrfs/super.c
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@ -1167,8 +1167,9 @@ static char *setup_root_args(char *args)
return buf; return buf;
} }
static struct dentry *mount_subvol(const char *subvol_name, int flags, static struct dentry *mount_subvol(const char *subvol_name, u64 subvol_objectid,
const char *device_name, char *data) int flags, const char *device_name,
char *data)
{ {
struct dentry *root; struct dentry *root;
struct vfsmount *mnt = NULL; struct vfsmount *mnt = NULL;
@ -1214,12 +1215,27 @@ static struct dentry *mount_subvol(const char *subvol_name, int flags,
/* mount_subtree() drops our reference on the vfsmount. */ /* mount_subtree() drops our reference on the vfsmount. */
mnt = NULL; mnt = NULL;
if (!IS_ERR(root) && !is_subvolume_inode(d_inode(root))) { if (!IS_ERR(root)) {
struct super_block *s = root->d_sb; struct super_block *s = root->d_sb;
dput(root); struct inode *root_inode = d_inode(root);
root = ERR_PTR(-EINVAL); u64 root_objectid = BTRFS_I(root_inode)->root->root_key.objectid;
deactivate_locked_super(s);
pr_err("BTRFS: '%s' is not a valid subvolume\n", subvol_name); ret = 0;
if (!is_subvolume_inode(root_inode)) {
pr_err("BTRFS: '%s' is not a valid subvolume\n",
subvol_name);
ret = -EINVAL;
}
if (subvol_objectid && root_objectid != subvol_objectid) {
pr_err("BTRFS: subvol '%s' does not match subvolid %llu\n",
subvol_name, subvol_objectid);
ret = -EINVAL;
}
if (ret) {
dput(root);
root = ERR_PTR(ret);
deactivate_locked_super(s);
}
} }
out: out:
@ -1312,7 +1328,8 @@ static struct dentry *btrfs_mount(struct file_system_type *fs_type, int flags,
if (subvol_name) { if (subvol_name) {
/* mount_subvol() will free subvol_name. */ /* mount_subvol() will free subvol_name. */
return mount_subvol(subvol_name, flags, device_name, data); return mount_subvol(subvol_name, subvol_objectid, flags,
device_name, data);
} }
security_init_mnt_opts(&new_sec_opts); security_init_mnt_opts(&new_sec_opts);