Btrfs: unify subvol= and subvolid= mounting
Currently, mounting a subvolume with subvolid= takes a different code path than mounting with subvol=. This isn't really a big deal except for the fact that mounts done with subvolid= or the default subvolume don't have a dentry that's connected to the dentry tree like in the subvol= case. To unify the code paths, when given subvolid= or using the default subvolume ID, translate it into a subvolume name by walking ROOT_BACKREFs in the root tree and INODE_REFs in the filesystem trees. 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
Chris Mason
parent
bb289b7be6
commit
05dbe6837b
238
fs/btrfs/super.c
238
fs/btrfs/super.c
|
|
@ -836,33 +836,153 @@ out:
|
|||
return error;
|
||||
}
|
||||
|
||||
static struct dentry *get_default_root(struct super_block *sb,
|
||||
u64 subvol_objectid)
|
||||
static char *get_subvol_name_from_objectid(struct btrfs_fs_info *fs_info,
|
||||
u64 subvol_objectid)
|
||||
{
|
||||
struct btrfs_root *root = fs_info->tree_root;
|
||||
struct btrfs_root *fs_root;
|
||||
struct btrfs_root_ref *root_ref;
|
||||
struct btrfs_inode_ref *inode_ref;
|
||||
struct btrfs_key key;
|
||||
struct btrfs_path *path = NULL;
|
||||
char *name = NULL, *ptr;
|
||||
u64 dirid;
|
||||
int len;
|
||||
int ret;
|
||||
|
||||
path = btrfs_alloc_path();
|
||||
if (!path) {
|
||||
ret = -ENOMEM;
|
||||
goto err;
|
||||
}
|
||||
path->leave_spinning = 1;
|
||||
|
||||
name = kmalloc(PATH_MAX, GFP_NOFS);
|
||||
if (!name) {
|
||||
ret = -ENOMEM;
|
||||
goto err;
|
||||
}
|
||||
ptr = name + PATH_MAX - 1;
|
||||
ptr[0] = '\0';
|
||||
|
||||
/*
|
||||
* Walk up the subvolume trees in the tree of tree roots by root
|
||||
* backrefs until we hit the top-level subvolume.
|
||||
*/
|
||||
while (subvol_objectid != BTRFS_FS_TREE_OBJECTID) {
|
||||
key.objectid = subvol_objectid;
|
||||
key.type = BTRFS_ROOT_BACKREF_KEY;
|
||||
key.offset = (u64)-1;
|
||||
|
||||
ret = btrfs_search_slot(NULL, root, &key, path, 0, 0);
|
||||
if (ret < 0) {
|
||||
goto err;
|
||||
} else if (ret > 0) {
|
||||
ret = btrfs_previous_item(root, path, subvol_objectid,
|
||||
BTRFS_ROOT_BACKREF_KEY);
|
||||
if (ret < 0) {
|
||||
goto err;
|
||||
} else if (ret > 0) {
|
||||
ret = -ENOENT;
|
||||
goto err;
|
||||
}
|
||||
}
|
||||
|
||||
btrfs_item_key_to_cpu(path->nodes[0], &key, path->slots[0]);
|
||||
subvol_objectid = key.offset;
|
||||
|
||||
root_ref = btrfs_item_ptr(path->nodes[0], path->slots[0],
|
||||
struct btrfs_root_ref);
|
||||
len = btrfs_root_ref_name_len(path->nodes[0], root_ref);
|
||||
ptr -= len + 1;
|
||||
if (ptr < name) {
|
||||
ret = -ENAMETOOLONG;
|
||||
goto err;
|
||||
}
|
||||
read_extent_buffer(path->nodes[0], ptr + 1,
|
||||
(unsigned long)(root_ref + 1), len);
|
||||
ptr[0] = '/';
|
||||
dirid = btrfs_root_ref_dirid(path->nodes[0], root_ref);
|
||||
btrfs_release_path(path);
|
||||
|
||||
key.objectid = subvol_objectid;
|
||||
key.type = BTRFS_ROOT_ITEM_KEY;
|
||||
key.offset = (u64)-1;
|
||||
fs_root = btrfs_read_fs_root_no_name(fs_info, &key);
|
||||
if (IS_ERR(fs_root)) {
|
||||
ret = PTR_ERR(fs_root);
|
||||
goto err;
|
||||
}
|
||||
|
||||
/*
|
||||
* Walk up the filesystem tree by inode refs until we hit the
|
||||
* root directory.
|
||||
*/
|
||||
while (dirid != BTRFS_FIRST_FREE_OBJECTID) {
|
||||
key.objectid = dirid;
|
||||
key.type = BTRFS_INODE_REF_KEY;
|
||||
key.offset = (u64)-1;
|
||||
|
||||
ret = btrfs_search_slot(NULL, fs_root, &key, path, 0, 0);
|
||||
if (ret < 0) {
|
||||
goto err;
|
||||
} else if (ret > 0) {
|
||||
ret = btrfs_previous_item(fs_root, path, dirid,
|
||||
BTRFS_INODE_REF_KEY);
|
||||
if (ret < 0) {
|
||||
goto err;
|
||||
} else if (ret > 0) {
|
||||
ret = -ENOENT;
|
||||
goto err;
|
||||
}
|
||||
}
|
||||
|
||||
btrfs_item_key_to_cpu(path->nodes[0], &key, path->slots[0]);
|
||||
dirid = key.offset;
|
||||
|
||||
inode_ref = btrfs_item_ptr(path->nodes[0],
|
||||
path->slots[0],
|
||||
struct btrfs_inode_ref);
|
||||
len = btrfs_inode_ref_name_len(path->nodes[0],
|
||||
inode_ref);
|
||||
ptr -= len + 1;
|
||||
if (ptr < name) {
|
||||
ret = -ENAMETOOLONG;
|
||||
goto err;
|
||||
}
|
||||
read_extent_buffer(path->nodes[0], ptr + 1,
|
||||
(unsigned long)(inode_ref + 1), len);
|
||||
ptr[0] = '/';
|
||||
btrfs_release_path(path);
|
||||
}
|
||||
}
|
||||
|
||||
btrfs_free_path(path);
|
||||
if (ptr == name + PATH_MAX - 1) {
|
||||
name[0] = '/';
|
||||
name[1] = '\0';
|
||||
} else {
|
||||
memmove(name, ptr, name + PATH_MAX - ptr);
|
||||
}
|
||||
return name;
|
||||
|
||||
err:
|
||||
btrfs_free_path(path);
|
||||
kfree(name);
|
||||
return ERR_PTR(ret);
|
||||
}
|
||||
|
||||
static int get_default_subvol_objectid(struct btrfs_fs_info *fs_info, u64 *objectid)
|
||||
{
|
||||
struct btrfs_fs_info *fs_info = btrfs_sb(sb);
|
||||
struct btrfs_root *root = fs_info->tree_root;
|
||||
struct btrfs_root *new_root;
|
||||
struct btrfs_dir_item *di;
|
||||
struct btrfs_path *path;
|
||||
struct btrfs_key location;
|
||||
struct inode *inode;
|
||||
u64 dir_id;
|
||||
int new = 0;
|
||||
|
||||
/*
|
||||
* We have a specific subvol we want to mount, just setup location and
|
||||
* go look up the root.
|
||||
*/
|
||||
if (subvol_objectid) {
|
||||
location.objectid = subvol_objectid;
|
||||
location.type = BTRFS_ROOT_ITEM_KEY;
|
||||
location.offset = (u64)-1;
|
||||
goto find_root;
|
||||
}
|
||||
|
||||
path = btrfs_alloc_path();
|
||||
if (!path)
|
||||
return ERR_PTR(-ENOMEM);
|
||||
return -ENOMEM;
|
||||
path->leave_spinning = 1;
|
||||
|
||||
/*
|
||||
|
|
@ -874,58 +994,23 @@ static struct dentry *get_default_root(struct super_block *sb,
|
|||
di = btrfs_lookup_dir_item(NULL, root, path, dir_id, "default", 7, 0);
|
||||
if (IS_ERR(di)) {
|
||||
btrfs_free_path(path);
|
||||
return ERR_CAST(di);
|
||||
return PTR_ERR(di);
|
||||
}
|
||||
if (!di) {
|
||||
/*
|
||||
* Ok the default dir item isn't there. This is weird since
|
||||
* it's always been there, but don't freak out, just try and
|
||||
* mount to root most subvolume.
|
||||
* mount the top-level subvolume.
|
||||
*/
|
||||
btrfs_free_path(path);
|
||||
dir_id = BTRFS_FIRST_FREE_OBJECTID;
|
||||
new_root = fs_info->fs_root;
|
||||
goto setup_root;
|
||||
*objectid = BTRFS_FS_TREE_OBJECTID;
|
||||
return 0;
|
||||
}
|
||||
|
||||
btrfs_dir_item_key_to_cpu(path->nodes[0], di, &location);
|
||||
btrfs_free_path(path);
|
||||
|
||||
find_root:
|
||||
new_root = btrfs_read_fs_root_no_name(fs_info, &location);
|
||||
if (IS_ERR(new_root))
|
||||
return ERR_CAST(new_root);
|
||||
|
||||
if (!(sb->s_flags & MS_RDONLY)) {
|
||||
int ret;
|
||||
down_read(&fs_info->cleanup_work_sem);
|
||||
ret = btrfs_orphan_cleanup(new_root);
|
||||
up_read(&fs_info->cleanup_work_sem);
|
||||
if (ret)
|
||||
return ERR_PTR(ret);
|
||||
}
|
||||
|
||||
dir_id = btrfs_root_dirid(&new_root->root_item);
|
||||
setup_root:
|
||||
location.objectid = dir_id;
|
||||
location.type = BTRFS_INODE_ITEM_KEY;
|
||||
location.offset = 0;
|
||||
|
||||
inode = btrfs_iget(sb, &location, new_root, &new);
|
||||
if (IS_ERR(inode))
|
||||
return ERR_CAST(inode);
|
||||
|
||||
/*
|
||||
* If we're just mounting the root most subvol put the inode and return
|
||||
* a reference to the dentry. We will have already gotten a reference
|
||||
* to the inode in btrfs_fill_super so we're good to go.
|
||||
*/
|
||||
if (!new && d_inode(sb->s_root) == inode) {
|
||||
iput(inode);
|
||||
return dget(sb->s_root);
|
||||
}
|
||||
|
||||
return d_obtain_root(inode);
|
||||
*objectid = location.objectid;
|
||||
return 0;
|
||||
}
|
||||
|
||||
static int btrfs_fill_super(struct super_block *sb,
|
||||
|
|
@ -1211,6 +1296,25 @@ static struct dentry *mount_subvol(const char *subvol_name, u64 subvol_objectid,
|
|||
goto out;
|
||||
}
|
||||
|
||||
if (!subvol_name) {
|
||||
if (!subvol_objectid) {
|
||||
ret = get_default_subvol_objectid(btrfs_sb(mnt->mnt_sb),
|
||||
&subvol_objectid);
|
||||
if (ret) {
|
||||
root = ERR_PTR(ret);
|
||||
goto out;
|
||||
}
|
||||
}
|
||||
subvol_name = get_subvol_name_from_objectid(btrfs_sb(mnt->mnt_sb),
|
||||
subvol_objectid);
|
||||
if (IS_ERR(subvol_name)) {
|
||||
root = ERR_CAST(subvol_name);
|
||||
subvol_name = NULL;
|
||||
goto out;
|
||||
}
|
||||
|
||||
}
|
||||
|
||||
root = mount_subtree(mnt, subvol_name);
|
||||
/* mount_subtree() drops our reference on the vfsmount. */
|
||||
mnt = NULL;
|
||||
|
|
@ -1227,6 +1331,11 @@ static struct dentry *mount_subvol(const char *subvol_name, u64 subvol_objectid,
|
|||
ret = -EINVAL;
|
||||
}
|
||||
if (subvol_objectid && root_objectid != subvol_objectid) {
|
||||
/*
|
||||
* This will also catch a race condition where a
|
||||
* subvolume which was passed by ID is renamed and
|
||||
* another subvolume is renamed over the old location.
|
||||
*/
|
||||
pr_err("BTRFS: subvol '%s' does not match subvolid %llu\n",
|
||||
subvol_name, subvol_objectid);
|
||||
ret = -EINVAL;
|
||||
|
|
@ -1306,7 +1415,6 @@ static struct dentry *btrfs_mount(struct file_system_type *fs_type, int flags,
|
|||
{
|
||||
struct block_device *bdev = NULL;
|
||||
struct super_block *s;
|
||||
struct dentry *root;
|
||||
struct btrfs_fs_devices *fs_devices = NULL;
|
||||
struct btrfs_fs_info *fs_info = NULL;
|
||||
struct security_mnt_opts new_sec_opts;
|
||||
|
|
@ -1326,7 +1434,7 @@ static struct dentry *btrfs_mount(struct file_system_type *fs_type, int flags,
|
|||
return ERR_PTR(error);
|
||||
}
|
||||
|
||||
if (subvol_name) {
|
||||
if (subvol_name || subvol_objectid != BTRFS_FS_TREE_OBJECTID) {
|
||||
/* mount_subvol() will free subvol_name. */
|
||||
return mount_subvol(subvol_name, subvol_objectid, flags,
|
||||
device_name, data);
|
||||
|
|
@ -1395,23 +1503,19 @@ static struct dentry *btrfs_mount(struct file_system_type *fs_type, int flags,
|
|||
error = btrfs_fill_super(s, fs_devices, data,
|
||||
flags & MS_SILENT ? 1 : 0);
|
||||
}
|
||||
|
||||
root = !error ? get_default_root(s, subvol_objectid) : ERR_PTR(error);
|
||||
if (IS_ERR(root)) {
|
||||
if (error) {
|
||||
deactivate_locked_super(s);
|
||||
error = PTR_ERR(root);
|
||||
goto error_sec_opts;
|
||||
}
|
||||
|
||||
fs_info = btrfs_sb(s);
|
||||
error = setup_security_options(fs_info, s, &new_sec_opts);
|
||||
if (error) {
|
||||
dput(root);
|
||||
deactivate_locked_super(s);
|
||||
goto error_sec_opts;
|
||||
}
|
||||
|
||||
return root;
|
||||
return dget(s->s_root);
|
||||
|
||||
error_close_devices:
|
||||
btrfs_close_devices(fs_devices);
|
||||
|
|
|
|||
Loading…
Reference in New Issue