Btrfs: add snapshot/subvolume destroy ioctl
This patch adds snapshot/subvolume destroy ioctl. A subvolume that isn't being
used and doesn't contains links to other subvolumes can be destroyed.
Signed-off-by: Yan Zheng <zheng.yan@oracle.com>
Signed-off-by: Chris Mason <chris.mason@oracle.com>
diff --git a/fs/btrfs/ioctl.c b/fs/btrfs/ioctl.c
index 9b3a887..a13fd55 100644
--- a/fs/btrfs/ioctl.c
+++ b/fs/btrfs/ioctl.c
@@ -230,8 +230,8 @@
struct btrfs_root_item root_item;
struct btrfs_inode_item *inode_item;
struct extent_buffer *leaf;
- struct btrfs_root *new_root = root;
- struct inode *dir;
+ struct btrfs_root *new_root;
+ struct inode *dir = dentry->d_parent->d_inode;
int ret;
int err;
u64 objectid;
@@ -241,7 +241,7 @@
ret = btrfs_check_metadata_free_space(root);
if (ret)
- goto fail_commit;
+ return ret;
trans = btrfs_start_transaction(root, 1);
BUG_ON(!trans);
@@ -304,11 +304,17 @@
if (ret)
goto fail;
+ key.offset = (u64)-1;
+ new_root = btrfs_read_fs_root_no_name(root->fs_info, &key);
+ BUG_ON(IS_ERR(new_root));
+
+ btrfs_record_root_in_trans(trans, new_root);
+
+ ret = btrfs_create_subvol_root(trans, new_root, new_dirid,
+ BTRFS_I(dir)->block_group);
/*
* insert the directory item
*/
- key.offset = (u64)-1;
- dir = dentry->d_parent->d_inode;
ret = btrfs_set_inode_index(dir, &index);
BUG_ON(ret);
@@ -325,30 +331,15 @@
ret = btrfs_add_root_ref(trans, root->fs_info->tree_root,
objectid, root->root_key.objectid,
dir->i_ino, index, name, namelen);
+
BUG_ON(ret);
- ret = btrfs_commit_transaction(trans, root);
- if (ret)
- goto fail_commit;
-
- new_root = btrfs_read_fs_root_no_name(root->fs_info, &key);
- BUG_ON(!new_root);
-
- trans = btrfs_start_transaction(new_root, 1);
- BUG_ON(!trans);
-
- ret = btrfs_create_subvol_root(trans, new_root, dentry, new_dirid,
- BTRFS_I(dir)->block_group);
- if (ret)
- goto fail;
-
+ d_instantiate(dentry, btrfs_lookup_dentry(dir, dentry));
fail:
nr = trans->blocks_used;
- err = btrfs_commit_transaction(trans, new_root);
+ err = btrfs_commit_transaction(trans, root);
if (err && !ret)
ret = err;
-fail_commit:
- btrfs_btree_balance_dirty(root, nr);
return ret;
}
@@ -409,14 +400,15 @@
* sys_mkdirat and vfs_mkdir, but we only do a single component lookup
* inside this filesystem so it's quite a bit simpler.
*/
-static noinline int btrfs_mksubvol(struct path *parent, char *name,
- int mode, int namelen,
+static noinline int btrfs_mksubvol(struct path *parent,
+ char *name, int namelen,
struct btrfs_root *snap_src)
{
+ struct inode *dir = parent->dentry->d_inode;
struct dentry *dentry;
int error;
- mutex_lock_nested(&parent->dentry->d_inode->i_mutex, I_MUTEX_PARENT);
+ mutex_lock_nested(&dir->i_mutex, I_MUTEX_PARENT);
dentry = lookup_one_len(name, parent->dentry, namelen);
error = PTR_ERR(dentry);
@@ -427,99 +419,39 @@
if (dentry->d_inode)
goto out_dput;
- if (!IS_POSIXACL(parent->dentry->d_inode))
- mode &= ~current_umask();
-
error = mnt_want_write(parent->mnt);
if (error)
goto out_dput;
- error = btrfs_may_create(parent->dentry->d_inode, dentry);
+ error = btrfs_may_create(dir, dentry);
if (error)
goto out_drop_write;
- /*
- * Actually perform the low-level subvolume creation after all
- * this VFS fuzz.
- *
- * Eventually we want to pass in an inode under which we create this
- * subvolume, but for now all are under the filesystem root.
- *
- * Also we should pass on the mode eventually to allow creating new
- * subvolume with specific mode bits.
- */
+ down_read(&BTRFS_I(dir)->root->fs_info->subvol_sem);
+
+ if (btrfs_root_refs(&BTRFS_I(dir)->root->root_item) == 0)
+ goto out_up_read;
+
if (snap_src) {
- struct dentry *dir = dentry->d_parent;
- struct dentry *test = dir->d_parent;
- struct btrfs_path *path = btrfs_alloc_path();
- int ret;
- u64 test_oid;
- u64 parent_oid = BTRFS_I(dir->d_inode)->root->root_key.objectid;
-
- test_oid = snap_src->root_key.objectid;
-
- ret = btrfs_find_root_ref(snap_src->fs_info->tree_root,
- path, parent_oid, test_oid);
- if (ret == 0)
- goto create;
- btrfs_release_path(snap_src->fs_info->tree_root, path);
-
- /* we need to make sure we aren't creating a directory loop
- * by taking a snapshot of something that has our current
- * subvol in its directory tree. So, this loops through
- * the dentries and checks the forward refs for each subvolume
- * to see if is references the subvolume where we are
- * placing this new snapshot.
- */
- while (1) {
- if (!test ||
- dir == snap_src->fs_info->sb->s_root ||
- test == snap_src->fs_info->sb->s_root ||
- test->d_inode->i_sb != snap_src->fs_info->sb) {
- break;
- }
- if (S_ISLNK(test->d_inode->i_mode)) {
- printk(KERN_INFO "Btrfs symlink in snapshot "
- "path, failed\n");
- error = -EMLINK;
- btrfs_free_path(path);
- goto out_drop_write;
- }
- test_oid =
- BTRFS_I(test->d_inode)->root->root_key.objectid;
- ret = btrfs_find_root_ref(snap_src->fs_info->tree_root,
- path, test_oid, parent_oid);
- if (ret == 0) {
- printk(KERN_INFO "Btrfs snapshot creation "
- "failed, looping\n");
- error = -EMLINK;
- btrfs_free_path(path);
- goto out_drop_write;
- }
- btrfs_release_path(snap_src->fs_info->tree_root, path);
- test = test->d_parent;
- }
-create:
- btrfs_free_path(path);
- error = create_snapshot(snap_src, dentry, name, namelen);
+ error = create_snapshot(snap_src, dentry,
+ name, namelen);
} else {
- error = create_subvol(BTRFS_I(parent->dentry->d_inode)->root,
- dentry, name, namelen);
+ error = create_subvol(BTRFS_I(dir)->root, dentry,
+ name, namelen);
}
- if (error)
- goto out_drop_write;
-
- fsnotify_mkdir(parent->dentry->d_inode, dentry);
+ if (!error)
+ fsnotify_mkdir(dir, dentry);
+out_up_read:
+ up_read(&BTRFS_I(dir)->root->fs_info->subvol_sem);
out_drop_write:
mnt_drop_write(parent->mnt);
out_dput:
dput(dentry);
out_unlock:
- mutex_unlock(&parent->dentry->d_inode->i_mutex);
+ mutex_unlock(&dir->i_mutex);
return error;
}
-
static int btrfs_defrag_file(struct file *file)
{
struct inode *inode = fdentry(file)->d_inode;
@@ -597,7 +529,8 @@
return 0;
}
-static int btrfs_ioctl_resize(struct btrfs_root *root, void __user *arg)
+static noinline int btrfs_ioctl_resize(struct btrfs_root *root,
+ void __user *arg)
{
u64 new_size;
u64 old_size;
@@ -706,10 +639,7 @@
{
struct btrfs_root *root = BTRFS_I(fdentry(file)->d_inode)->root;
struct btrfs_ioctl_vol_args *vol_args;
- struct btrfs_dir_item *di;
- struct btrfs_path *path;
struct file *src_file;
- u64 root_dirid;
int namelen;
int ret = 0;
@@ -727,32 +657,9 @@
goto out;
}
- path = btrfs_alloc_path();
- if (!path) {
- ret = -ENOMEM;
- goto out;
- }
-
- root_dirid = root->fs_info->sb->s_root->d_inode->i_ino,
- di = btrfs_lookup_dir_item(NULL, root->fs_info->tree_root,
- path, root_dirid,
- vol_args->name, namelen, 0);
- btrfs_free_path(path);
-
- if (di && !IS_ERR(di)) {
- ret = -EEXIST;
- goto out;
- }
-
- if (IS_ERR(di)) {
- ret = PTR_ERR(di);
- goto out;
- }
-
if (subvol) {
- ret = btrfs_mksubvol(&file->f_path, vol_args->name,
- file->f_path.dentry->d_inode->i_mode,
- namelen, NULL);
+ ret = btrfs_mksubvol(&file->f_path, vol_args->name, namelen,
+ NULL);
} else {
struct inode *src_inode;
src_file = fget(vol_args->fd);
@@ -769,17 +676,156 @@
fput(src_file);
goto out;
}
- ret = btrfs_mksubvol(&file->f_path, vol_args->name,
- file->f_path.dentry->d_inode->i_mode,
- namelen, BTRFS_I(src_inode)->root);
+ ret = btrfs_mksubvol(&file->f_path, vol_args->name, namelen,
+ BTRFS_I(src_inode)->root);
fput(src_file);
}
-
out:
kfree(vol_args);
return ret;
}
+/*
+ * helper to check if the subvolume references other subvolumes
+ */
+static noinline int may_destroy_subvol(struct btrfs_root *root)
+{
+ struct btrfs_path *path;
+ struct btrfs_key key;
+ int ret;
+
+ path = btrfs_alloc_path();
+ if (!path)
+ return -ENOMEM;
+
+ key.objectid = root->root_key.objectid;
+ key.type = BTRFS_ROOT_REF_KEY;
+ key.offset = (u64)-1;
+
+ ret = btrfs_search_slot(NULL, root->fs_info->tree_root,
+ &key, path, 0, 0);
+ if (ret < 0)
+ goto out;
+ BUG_ON(ret == 0);
+
+ ret = 0;
+ if (path->slots[0] > 0) {
+ path->slots[0]--;
+ btrfs_item_key_to_cpu(path->nodes[0], &key, path->slots[0]);
+ if (key.objectid == root->root_key.objectid &&
+ key.type == BTRFS_ROOT_REF_KEY)
+ ret = -ENOTEMPTY;
+ }
+out:
+ btrfs_free_path(path);
+ return ret;
+}
+
+static noinline int btrfs_ioctl_snap_destroy(struct file *file,
+ void __user *arg)
+{
+ struct dentry *parent = fdentry(file);
+ struct dentry *dentry;
+ struct inode *dir = parent->d_inode;
+ struct inode *inode;
+ struct btrfs_root *root = BTRFS_I(dir)->root;
+ struct btrfs_root *dest = NULL;
+ struct btrfs_ioctl_vol_args *vol_args;
+ struct btrfs_trans_handle *trans;
+ int namelen;
+ int ret;
+ int err = 0;
+
+ if (!capable(CAP_SYS_ADMIN))
+ return -EPERM;
+
+ vol_args = memdup_user(arg, sizeof(*vol_args));
+ if (IS_ERR(vol_args))
+ return PTR_ERR(vol_args);
+
+ vol_args->name[BTRFS_PATH_NAME_MAX] = '\0';
+ namelen = strlen(vol_args->name);
+ if (strchr(vol_args->name, '/') ||
+ strncmp(vol_args->name, "..", namelen) == 0) {
+ err = -EINVAL;
+ goto out;
+ }
+
+ err = mnt_want_write(file->f_path.mnt);
+ if (err)
+ goto out;
+
+ mutex_lock_nested(&dir->i_mutex, I_MUTEX_PARENT);
+ dentry = lookup_one_len(vol_args->name, parent, namelen);
+ if (IS_ERR(dentry)) {
+ err = PTR_ERR(dentry);
+ goto out_unlock_dir;
+ }
+
+ if (!dentry->d_inode) {
+ err = -ENOENT;
+ goto out_dput;
+ }
+
+ inode = dentry->d_inode;
+ if (inode->i_ino != BTRFS_FIRST_FREE_OBJECTID) {
+ err = -EINVAL;
+ goto out_dput;
+ }
+
+ dest = BTRFS_I(inode)->root;
+
+ mutex_lock(&inode->i_mutex);
+ err = d_invalidate(dentry);
+ if (err)
+ goto out_unlock;
+
+ down_write(&root->fs_info->subvol_sem);
+
+ err = may_destroy_subvol(dest);
+ if (err)
+ goto out_up_write;
+
+ trans = btrfs_start_transaction(root, 1);
+ ret = btrfs_unlink_subvol(trans, root, dir,
+ dest->root_key.objectid,
+ dentry->d_name.name,
+ dentry->d_name.len);
+ BUG_ON(ret);
+
+ btrfs_record_root_in_trans(trans, dest);
+
+ memset(&dest->root_item.drop_progress, 0,
+ sizeof(dest->root_item.drop_progress));
+ dest->root_item.drop_level = 0;
+ btrfs_set_root_refs(&dest->root_item, 0);
+
+ ret = btrfs_insert_orphan_item(trans,
+ root->fs_info->tree_root,
+ dest->root_key.objectid);
+ BUG_ON(ret);
+
+ ret = btrfs_commit_transaction(trans, root);
+ BUG_ON(ret);
+ inode->i_flags |= S_DEAD;
+out_up_write:
+ up_write(&root->fs_info->subvol_sem);
+out_unlock:
+ mutex_unlock(&inode->i_mutex);
+ if (!err) {
+ btrfs_invalidate_inodes(dest);
+ d_delete(dentry);
+ }
+out_dput:
+ dput(dentry);
+out_unlock_dir:
+ mutex_unlock(&dir->i_mutex);
+ mnt_drop_write(file->f_path.mnt);
+out:
+ kfree(vol_args);
+ return err;
+}
+
static int btrfs_ioctl_defrag(struct file *file)
{
struct inode *inode = fdentry(file)->d_inode;
@@ -853,8 +899,8 @@
return ret;
}
-static long btrfs_ioctl_clone(struct file *file, unsigned long srcfd,
- u64 off, u64 olen, u64 destoff)
+static noinline long btrfs_ioctl_clone(struct file *file, unsigned long srcfd,
+ u64 off, u64 olen, u64 destoff)
{
struct inode *inode = fdentry(file)->d_inode;
struct btrfs_root *root = BTRFS_I(inode)->root;
@@ -1246,6 +1292,8 @@
return btrfs_ioctl_snap_create(file, argp, 0);
case BTRFS_IOC_SUBVOL_CREATE:
return btrfs_ioctl_snap_create(file, argp, 1);
+ case BTRFS_IOC_SNAP_DESTROY:
+ return btrfs_ioctl_snap_destroy(file, argp);
case BTRFS_IOC_DEFRAG:
return btrfs_ioctl_defrag(file);
case BTRFS_IOC_RESIZE: