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/disk-io.c b/fs/btrfs/disk-io.c
index a4f5310..a0d41e7 100644
--- a/fs/btrfs/disk-io.c
+++ b/fs/btrfs/disk-io.c
@@ -1378,8 +1378,10 @@
err = bdi_register(bdi, NULL, "btrfs-%d",
atomic_inc_return(&btrfs_bdi_num));
- if (err)
+ if (err) {
+ bdi_destroy(bdi);
return err;
+ }
bdi->ra_pages = default_backing_dev_info.ra_pages;
bdi->unplug_io_fn = btrfs_unplug_io_fn;
@@ -1469,9 +1471,12 @@
break;
vfs_check_frozen(root->fs_info->sb, SB_FREEZE_WRITE);
- mutex_lock(&root->fs_info->cleaner_mutex);
- btrfs_clean_old_snapshots(root);
- mutex_unlock(&root->fs_info->cleaner_mutex);
+
+ if (!(root->fs_info->sb->s_flags & MS_RDONLY) &&
+ mutex_trylock(&root->fs_info->cleaner_mutex)) {
+ btrfs_clean_old_snapshots(root);
+ mutex_unlock(&root->fs_info->cleaner_mutex);
+ }
if (freezing(current)) {
refrigerator();
@@ -1576,7 +1581,26 @@
err = -ENOMEM;
goto fail;
}
- INIT_RADIX_TREE(&fs_info->fs_roots_radix, GFP_NOFS);
+
+ ret = init_srcu_struct(&fs_info->subvol_srcu);
+ if (ret) {
+ err = ret;
+ goto fail;
+ }
+
+ ret = setup_bdi(fs_info, &fs_info->bdi);
+ if (ret) {
+ err = ret;
+ goto fail_srcu;
+ }
+
+ fs_info->btree_inode = new_inode(sb);
+ if (!fs_info->btree_inode) {
+ err = -ENOMEM;
+ goto fail_bdi;
+ }
+
+ INIT_RADIX_TREE(&fs_info->fs_roots_radix, GFP_ATOMIC);
INIT_LIST_HEAD(&fs_info->trans_list);
INIT_LIST_HEAD(&fs_info->dead_roots);
INIT_LIST_HEAD(&fs_info->hashers);
@@ -1586,6 +1610,7 @@
spin_lock_init(&fs_info->delalloc_lock);
spin_lock_init(&fs_info->new_trans_lock);
spin_lock_init(&fs_info->ref_cache_lock);
+ spin_lock_init(&fs_info->fs_roots_radix_lock);
init_completion(&fs_info->kobj_unregister);
fs_info->tree_root = tree_root;
@@ -1604,11 +1629,6 @@
fs_info->sb = sb;
fs_info->max_extent = (u64)-1;
fs_info->max_inline = 8192 * 1024;
- if (setup_bdi(fs_info, &fs_info->bdi))
- goto fail_bdi;
- fs_info->btree_inode = new_inode(sb);
- fs_info->btree_inode->i_ino = 1;
- fs_info->btree_inode->i_nlink = 1;
fs_info->metadata_ratio = 8;
fs_info->thread_pool_size = min_t(unsigned long,
@@ -1620,6 +1640,8 @@
sb->s_blocksize = 4096;
sb->s_blocksize_bits = blksize_bits(4096);
+ fs_info->btree_inode->i_ino = BTRFS_BTREE_INODE_OBJECTID;
+ fs_info->btree_inode->i_nlink = 1;
/*
* we set the i_size on the btree inode to the max possible int.
* the real end of the address space is determined by all of
@@ -1638,6 +1660,11 @@
BTRFS_I(fs_info->btree_inode)->io_tree.ops = &btree_extent_io_ops;
+ BTRFS_I(fs_info->btree_inode)->root = tree_root;
+ memset(&BTRFS_I(fs_info->btree_inode)->location, 0,
+ sizeof(struct btrfs_key));
+ BTRFS_I(fs_info->btree_inode)->dummy_inode = 1;
+
spin_lock_init(&fs_info->block_group_cache_lock);
fs_info->block_group_cache_tree.rb_node = NULL;
@@ -1648,21 +1675,16 @@
fs_info->pinned_extents = &fs_info->freed_extents[0];
fs_info->do_barriers = 1;
- BTRFS_I(fs_info->btree_inode)->root = tree_root;
- memset(&BTRFS_I(fs_info->btree_inode)->location, 0,
- sizeof(struct btrfs_key));
- insert_inode_hash(fs_info->btree_inode);
mutex_init(&fs_info->trans_mutex);
mutex_init(&fs_info->ordered_operations_mutex);
mutex_init(&fs_info->tree_log_mutex);
- mutex_init(&fs_info->drop_mutex);
mutex_init(&fs_info->chunk_mutex);
mutex_init(&fs_info->transaction_kthread_mutex);
mutex_init(&fs_info->cleaner_mutex);
mutex_init(&fs_info->volume_mutex);
- mutex_init(&fs_info->tree_reloc_mutex);
init_rwsem(&fs_info->extent_commit_sem);
+ init_rwsem(&fs_info->subvol_sem);
btrfs_init_free_cluster(&fs_info->meta_alloc_cluster);
btrfs_init_free_cluster(&fs_info->data_alloc_cluster);
@@ -1941,6 +1963,9 @@
}
}
+ ret = btrfs_find_orphan_roots(tree_root);
+ BUG_ON(ret);
+
if (!(sb->s_flags & MS_RDONLY)) {
ret = btrfs_recover_relocation(tree_root);
BUG_ON(ret);
@@ -2000,6 +2025,8 @@
btrfs_mapping_tree_free(&fs_info->mapping_tree);
fail_bdi:
bdi_destroy(&fs_info->bdi);
+fail_srcu:
+ cleanup_srcu_struct(&fs_info->subvol_srcu);
fail:
kfree(extent_root);
kfree(tree_root);
@@ -2263,6 +2290,10 @@
radix_tree_delete(&fs_info->fs_roots_radix,
(unsigned long)root->root_key.objectid);
spin_unlock(&fs_info->fs_roots_radix_lock);
+
+ if (btrfs_root_refs(&root->root_item) == 0)
+ synchronize_srcu(&fs_info->subvol_srcu);
+
free_fs_root(root);
return 0;
}
@@ -2286,6 +2317,20 @@
struct btrfs_root *gang[8];
int i;
+ while (!list_empty(&fs_info->dead_roots)) {
+ gang[0] = list_entry(fs_info->dead_roots.next,
+ struct btrfs_root, root_list);
+ list_del(&gang[0]->root_list);
+
+ if (gang[0]->in_radix) {
+ btrfs_free_fs_root(fs_info, gang[0]);
+ } else {
+ free_extent_buffer(gang[0]->node);
+ free_extent_buffer(gang[0]->commit_root);
+ kfree(gang[0]);
+ }
+ }
+
while (1) {
ret = radix_tree_gang_lookup(&fs_info->fs_roots_radix,
(void **)gang, 0,
@@ -2315,9 +2360,6 @@
root_objectid = gang[ret - 1]->root_key.objectid + 1;
for (i = 0; i < ret; i++) {
root_objectid = gang[i]->root_key.objectid;
- ret = btrfs_find_dead_roots(fs_info->tree_root,
- root_objectid);
- BUG_ON(ret);
btrfs_orphan_cleanup(gang[i]);
}
root_objectid++;
@@ -2405,6 +2447,7 @@
btrfs_mapping_tree_free(&fs_info->mapping_tree);
bdi_destroy(&fs_info->bdi);
+ cleanup_srcu_struct(&fs_info->subvol_srcu);
kfree(fs_info->extent_root);
kfree(fs_info->tree_root);