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/inode.c b/fs/btrfs/inode.c
index 6036b36..db9cbd9 100644
--- a/fs/btrfs/inode.c
+++ b/fs/btrfs/inode.c
@@ -3089,6 +3089,11 @@
}
btrfs_wait_ordered_range(inode, 0, (u64)-1);
+ if (inode->i_nlink > 0) {
+ BUG_ON(btrfs_root_refs(&root->root_item) != 0);
+ goto no_delete;
+ }
+
btrfs_i_size_write(inode, 0);
trans = btrfs_join_transaction(root, 1);
@@ -3225,11 +3230,13 @@
struct btrfs_inode *entry;
struct rb_node **p;
struct rb_node *parent;
-
again:
p = &root->inode_tree.rb_node;
parent = NULL;
+ if (hlist_unhashed(&inode->i_hash))
+ return;
+
spin_lock(&root->inode_lock);
while (*p) {
parent = *p;
@@ -3256,13 +3263,87 @@
static void inode_tree_del(struct inode *inode)
{
struct btrfs_root *root = BTRFS_I(inode)->root;
+ int empty = 0;
spin_lock(&root->inode_lock);
if (!RB_EMPTY_NODE(&BTRFS_I(inode)->rb_node)) {
rb_erase(&BTRFS_I(inode)->rb_node, &root->inode_tree);
RB_CLEAR_NODE(&BTRFS_I(inode)->rb_node);
+ empty = RB_EMPTY_ROOT(&root->inode_tree);
}
spin_unlock(&root->inode_lock);
+
+ if (empty && btrfs_root_refs(&root->root_item) == 0) {
+ synchronize_srcu(&root->fs_info->subvol_srcu);
+ spin_lock(&root->inode_lock);
+ empty = RB_EMPTY_ROOT(&root->inode_tree);
+ spin_unlock(&root->inode_lock);
+ if (empty)
+ btrfs_add_dead_root(root);
+ }
+}
+
+int btrfs_invalidate_inodes(struct btrfs_root *root)
+{
+ struct rb_node *node;
+ struct rb_node *prev;
+ struct btrfs_inode *entry;
+ struct inode *inode;
+ u64 objectid = 0;
+
+ WARN_ON(btrfs_root_refs(&root->root_item) != 0);
+
+ spin_lock(&root->inode_lock);
+again:
+ node = root->inode_tree.rb_node;
+ prev = NULL;
+ while (node) {
+ prev = node;
+ entry = rb_entry(node, struct btrfs_inode, rb_node);
+
+ if (objectid < entry->vfs_inode.i_ino)
+ node = node->rb_left;
+ else if (objectid > entry->vfs_inode.i_ino)
+ node = node->rb_right;
+ else
+ break;
+ }
+ if (!node) {
+ while (prev) {
+ entry = rb_entry(prev, struct btrfs_inode, rb_node);
+ if (objectid <= entry->vfs_inode.i_ino) {
+ node = prev;
+ break;
+ }
+ prev = rb_next(prev);
+ }
+ }
+ while (node) {
+ entry = rb_entry(node, struct btrfs_inode, rb_node);
+ objectid = entry->vfs_inode.i_ino + 1;
+ inode = igrab(&entry->vfs_inode);
+ if (inode) {
+ spin_unlock(&root->inode_lock);
+ if (atomic_read(&inode->i_count) > 1)
+ d_prune_aliases(inode);
+ /*
+ * btrfs_drop_inode will remove it from
+ * the inode cache when its usage count
+ * hits zero.
+ */
+ iput(inode);
+ cond_resched();
+ spin_lock(&root->inode_lock);
+ goto again;
+ }
+
+ if (cond_resched_lock(&root->inode_lock))
+ goto again;
+
+ node = rb_next(node);
+ }
+ spin_unlock(&root->inode_lock);
+ return 0;
}
static noinline void init_btrfs_i(struct inode *inode)
@@ -3379,8 +3460,11 @@
struct btrfs_root *root = BTRFS_I(dir)->root;
struct btrfs_root *sub_root = root;
struct btrfs_key location;
+ int index;
int ret;
+ dentry->d_op = &btrfs_dentry_operations;
+
if (dentry->d_name.len > BTRFS_NAME_LEN)
return ERR_PTR(-ENAMETOOLONG);
@@ -3399,6 +3483,7 @@
BUG_ON(location.type != BTRFS_ROOT_ITEM_KEY);
+ index = srcu_read_lock(&root->fs_info->subvol_srcu);
ret = fixup_tree_root_location(root, dir, dentry,
&location, &sub_root);
if (ret < 0) {
@@ -3409,9 +3494,24 @@
} else {
inode = btrfs_iget(dir->i_sb, &location, sub_root);
}
+ srcu_read_unlock(&root->fs_info->subvol_srcu, index);
+
return inode;
}
+static int btrfs_dentry_delete(struct dentry *dentry)
+{
+ struct btrfs_root *root;
+
+ if (!dentry->d_inode)
+ return 0;
+
+ root = BTRFS_I(dentry->d_inode)->root;
+ if (btrfs_root_refs(&root->root_item) == 0)
+ return 1;
+ return 0;
+}
+
static struct dentry *btrfs_lookup(struct inode *dir, struct dentry *dentry,
struct nameidata *nd)
{
@@ -4773,11 +4873,11 @@
* create a new subvolume directory/inode (helper for the ioctl).
*/
int btrfs_create_subvol_root(struct btrfs_trans_handle *trans,
- struct btrfs_root *new_root, struct dentry *dentry,
+ struct btrfs_root *new_root,
u64 new_dirid, u64 alloc_hint)
{
struct inode *inode;
- int error;
+ int err;
u64 index = 0;
inode = btrfs_new_inode(trans, new_root, NULL, "..", 2, new_dirid,
@@ -4790,11 +4890,10 @@
inode->i_nlink = 1;
btrfs_i_size_write(inode, 0);
- error = btrfs_update_inode(trans, new_root, inode);
- if (error)
- return error;
+ err = btrfs_update_inode(trans, new_root, inode);
+ BUG_ON(err);
- d_instantiate(dentry, inode);
+ iput(inode);
return 0;
}
@@ -4872,6 +4971,16 @@
kmem_cache_free(btrfs_inode_cachep, BTRFS_I(inode));
}
+void btrfs_drop_inode(struct inode *inode)
+{
+ struct btrfs_root *root = BTRFS_I(inode)->root;
+
+ if (inode->i_nlink > 0 && btrfs_root_refs(&root->root_item) == 0)
+ generic_delete_inode(inode);
+ else
+ generic_drop_inode(inode);
+}
+
static void init_once(void *foo)
{
struct btrfs_inode *ei = (struct btrfs_inode *) foo;
@@ -4973,6 +5082,10 @@
old_inode->i_size > BTRFS_ORDERED_OPERATIONS_FLUSH_LIMIT)
filemap_flush(old_inode->i_mapping);
+ /* close the racy window with snapshot create/destroy ioctl */
+ if (old_inode->i_ino == BTRFS_FIRST_FREE_OBJECTID)
+ down_read(&root->fs_info->subvol_sem);
+
trans = btrfs_start_transaction(root, 1);
if (dest != root)
@@ -5062,6 +5175,8 @@
btrfs_end_transaction_throttle(trans, root);
+ if (old_inode->i_ino == BTRFS_FIRST_FREE_OBJECTID)
+ up_read(&root->fs_info->subvol_sem);
return ret;
}
@@ -5420,6 +5535,7 @@
.lookup = btrfs_lookup,
.permission = btrfs_permission,
};
+
static struct file_operations btrfs_dir_file_operations = {
.llseek = generic_file_llseek,
.read = generic_read_dir,
@@ -5506,3 +5622,7 @@
.listxattr = btrfs_listxattr,
.removexattr = btrfs_removexattr,
};
+
+struct dentry_operations btrfs_dentry_operations = {
+ .d_delete = btrfs_dentry_delete,
+};