Btrfs: fix wrong reserved space in qgroup during snap/subv creation

There are two problems in the space reservation of the snapshot/
subvolume creation.
- don't reserve the space for the root item insertion
- the space which is reserved in the qgroup is different with
  the free space reservation. we need reserve free space for
  7 items, but in qgroup reservation, we need reserve space only
  for 3 items.

So we implement new metadata reservation functions for the
snapshot/subvolume creation.

Signed-off-by: Miao Xie <miaox@cn.fujitsu.com>
Signed-off-by: Josef Bacik <jbacik@fusionio.com>

diff --git a/fs/btrfs/ctree.h b/fs/btrfs/ctree.h
index ae8dcc4..0d82922 100644 (file)
--- a/fs/btrfs/ctree.h
+++ b/fs/btrfs/ctree.h
@@ -3106,8 +3106,13 @@ void btrfs_trans_release_metadata(struct btrfs_trans_handle *trans,
 int btrfs_orphan_reserve_metadata(struct btrfs_trans_handle *trans,
                                  struct inode *inode);
 void btrfs_orphan_release_metadata(struct inode *inode);
-int btrfs_snap_reserve_metadata(struct btrfs_trans_handle *trans,
-                               struct btrfs_pending_snapshot *pending);
+int btrfs_subvolume_reserve_metadata(struct btrfs_root *root,
+                                    struct btrfs_block_rsv *rsv,
+                                    int nitems,
+                                    u64 *qgroup_reserved);
+void btrfs_subvolume_release_metadata(struct btrfs_root *root,
+                                     struct btrfs_block_rsv *rsv,
+                                     u64 qgroup_reserved);
 int btrfs_delalloc_reserve_metadata(struct inode *inode, u64 num_bytes);
 void btrfs_delalloc_release_metadata(struct inode *inode, u64 num_bytes);
 int btrfs_delalloc_reserve_space(struct inode *inode, u64 num_bytes);

diff --git a/fs/btrfs/extent-tree.c b/fs/btrfs/extent-tree.c
index 5681a91..7cb9d73 100644 (file)
--- a/fs/btrfs/extent-tree.c
+++ b/fs/btrfs/extent-tree.c
@@ -4560,19 +4560,60 @@ void btrfs_orphan_release_metadata(struct inode *inode)
        btrfs_block_rsv_release(root, root->orphan_block_rsv, num_bytes);
 }
 
-int btrfs_snap_reserve_metadata(struct btrfs_trans_handle *trans,
-                               struct btrfs_pending_snapshot *pending)
+/*
+ * btrfs_subvolume_reserve_metadata() - reserve space for subvolume operation
+ * root: the root of the parent directory
+ * rsv: block reservation
+ * items: the number of items that we need do reservation
+ * qgroup_reserved: used to return the reserved size in qgroup
+ *
+ * This function is used to reserve the space for snapshot/subvolume
+ * creation and deletion. Those operations are different with the
+ * common file/directory operations, they change two fs/file trees
+ * and root tree, the number of items that the qgroup reserves is
+ * different with the free space reservation. So we can not use
+ * the space reseravtion mechanism in start_transaction().
+ */
+int btrfs_subvolume_reserve_metadata(struct btrfs_root *root,
+                                    struct btrfs_block_rsv *rsv,
+                                    int items,
+                                    u64 *qgroup_reserved)
 {
-       struct btrfs_root *root = pending->root;
-       struct btrfs_block_rsv *src_rsv = get_block_rsv(trans, root);
-       struct btrfs_block_rsv *dst_rsv = &pending->block_rsv;
-       /*
-        * two for root back/forward refs, two for directory entries,
-        * one for root of the snapshot and one for parent inode.
-        */
-       u64 num_bytes = btrfs_calc_trans_metadata_size(root, 6);
-       dst_rsv->space_info = src_rsv->space_info;
-       return block_rsv_migrate_bytes(src_rsv, dst_rsv, num_bytes);
+       u64 num_bytes;
+       int ret;
+
+       if (root->fs_info->quota_enabled) {
+               /* One for parent inode, two for dir entries */
+               num_bytes = 3 * root->leafsize;
+               ret = btrfs_qgroup_reserve(root, num_bytes);
+               if (ret)
+                       return ret;
+       } else {
+               num_bytes = 0;
+       }
+
+       *qgroup_reserved = num_bytes;
+
+       num_bytes = btrfs_calc_trans_metadata_size(root, items);
+       rsv->space_info = __find_space_info(root->fs_info,
+                                           BTRFS_BLOCK_GROUP_METADATA);
+       ret = btrfs_block_rsv_add(root, rsv, num_bytes,
+                                 BTRFS_RESERVE_FLUSH_ALL);
+       if (ret) {
+               if (*qgroup_reserved)
+                       btrfs_qgroup_free(root, *qgroup_reserved);
+       }
+
+       return ret;
+}
+
+void btrfs_subvolume_release_metadata(struct btrfs_root *root,
+                                     struct btrfs_block_rsv *rsv,
+                                     u64 qgroup_reserved)
+{
+       btrfs_block_rsv_release(root, rsv, (u64)-1);
+       if (qgroup_reserved)
+               btrfs_qgroup_free(root, qgroup_reserved);
 }
 
 /**

diff --git a/fs/btrfs/ioctl.c b/fs/btrfs/ioctl.c
index 8dcd4ff..56d9254 100644 (file)
--- a/fs/btrfs/ioctl.c
+++ b/fs/btrfs/ioctl.c
@@ -363,7 +363,7 @@ static noinline int btrfs_ioctl_fitrim(struct file *file, void __user *arg)
        return 0;
 }
 
-static noinline int create_subvol(struct btrfs_root *root,
+static noinline int create_subvol(struct inode *dir,
                                  struct dentry *dentry,
                                  char *name, int namelen,
                                  u64 *async_transid,
@@ -374,32 +374,39 @@ static noinline int create_subvol(struct btrfs_root *root,
        struct btrfs_root_item root_item;
        struct btrfs_inode_item *inode_item;
        struct extent_buffer *leaf;
+       struct btrfs_root *root = BTRFS_I(dir)->root;
        struct btrfs_root *new_root;
-       struct dentry *parent = dentry->d_parent;
-       struct inode *dir;
+       struct btrfs_block_rsv block_rsv;
        struct timespec cur_time = CURRENT_TIME;
        int ret;
        int err;
        u64 objectid;
        u64 new_dirid = BTRFS_FIRST_FREE_OBJECTID;
        u64 index = 0;
+       u64 qgroup_reserved;
        uuid_le new_uuid;
 
        ret = btrfs_find_free_objectid(root->fs_info->tree_root, &objectid);
        if (ret)
                return ret;
 
-       dir = parent->d_inode;
-
+       btrfs_init_block_rsv(&block_rsv, BTRFS_BLOCK_RSV_TEMP);
        /*
-        * 1 - inode item
-        * 2 - refs
-        * 1 - root item
-        * 2 - dir items
+        * The same as the snapshot creation, please see the comment
+        * of create_snapshot().
         */
-       trans = btrfs_start_transaction(root, 6);
-       if (IS_ERR(trans))
-               return PTR_ERR(trans);
+       ret = btrfs_subvolume_reserve_metadata(root, &block_rsv,
+                                              7, &qgroup_reserved);
+       if (ret)
+               return ret;
+
+       trans = btrfs_start_transaction(root, 0);
+       if (IS_ERR(trans)) {
+               ret = PTR_ERR(trans);
+               goto out;
+       }
+       trans->block_rsv = &block_rsv;
+       trans->bytes_reserved = block_rsv.size;
 
        ret = btrfs_qgroup_inherit(trans, root->fs_info, 0, objectid, inherit);
        if (ret)
@@ -515,6 +522,8 @@ static noinline int create_subvol(struct btrfs_root *root,
        BUG_ON(ret);
 
 fail:
+       trans->block_rsv = NULL;
+       trans->bytes_reserved = 0;
        if (async_transid) {
                *async_transid = trans->transid;
                err = btrfs_commit_transaction_async(trans, root, 1);
@@ -526,7 +535,8 @@ fail:
 
        if (!ret)
                d_instantiate(dentry, btrfs_lookup_dentry(dir, dentry));
-
+out:
+       btrfs_subvolume_release_metadata(root, &block_rsv, qgroup_reserved);
        return ret;
 }
 
@@ -549,21 +559,31 @@ static int create_snapshot(struct btrfs_root *root, struct inode *dir,
 
        btrfs_init_block_rsv(&pending_snapshot->block_rsv,
                             BTRFS_BLOCK_RSV_TEMP);
+       /*
+        * 1 - parent dir inode
+        * 2 - dir entries
+        * 1 - root item
+        * 2 - root ref/backref
+        * 1 - root of snapshot
+        */
+       ret = btrfs_subvolume_reserve_metadata(BTRFS_I(dir)->root,
+                                       &pending_snapshot->block_rsv, 7,
+                                       &pending_snapshot->qgroup_reserved);
+       if (ret)
+               goto out;
+
        pending_snapshot->dentry = dentry;
        pending_snapshot->root = root;
        pending_snapshot->readonly = readonly;
        pending_snapshot->dir = dir;
        pending_snapshot->inherit = inherit;
 
-       trans = btrfs_start_transaction(root->fs_info->extent_root, 6);
+       trans = btrfs_start_transaction(root, 0);
        if (IS_ERR(trans)) {
                ret = PTR_ERR(trans);
                goto fail;
        }
 
-       ret = btrfs_snap_reserve_metadata(trans, pending_snapshot);
-       BUG_ON(ret);
-
        spin_lock(&root->fs_info->trans_lock);
        list_add(&pending_snapshot->list,
                 &trans->transaction->pending_snapshots);
@@ -600,6 +620,10 @@ static int create_snapshot(struct btrfs_root *root, struct inode *dir,
        d_instantiate(dentry, inode);
        ret = 0;
 fail:
+       btrfs_subvolume_release_metadata(BTRFS_I(dir)->root,
+                                        &pending_snapshot->block_rsv,
+                                        pending_snapshot->qgroup_reserved);
+out:
        kfree(pending_snapshot);
        return ret;
 }
@@ -733,8 +757,8 @@ static noinline int btrfs_mksubvol(struct path *parent,
                error = create_snapshot(snap_src, dir, dentry, name, namelen,
                                        async_transid, readonly, inherit);
        } else {
-               error = create_subvol(BTRFS_I(dir)->root, dentry,
-                                     name, namelen, async_transid, inherit);
+               error = create_subvol(dir, dentry, name, namelen,
+                                     async_transid, inherit);
        }
        if (!error)
                fsnotify_mkdir(dir, dentry);

diff --git a/fs/btrfs/transaction.c b/fs/btrfs/transaction.c
index 71de435..f11c2e0 100644 (file)
--- a/fs/btrfs/transaction.c
+++ b/fs/btrfs/transaction.c
@@ -1082,7 +1082,7 @@ static noinline int create_pending_snapshot(struct btrfs_trans_handle *trans,
        path = btrfs_alloc_path();
        if (!path) {
                ret = pending->error = -ENOMEM;
-               goto path_alloc_fail;
+               return ret;
        }
 
        new_root_item = kmalloc(sizeof(*new_root_item), GFP_NOFS);
@@ -1279,8 +1279,6 @@ no_free_objectid:
        kfree(new_root_item);
 root_item_alloc_fail:
        btrfs_free_path(path);
-path_alloc_fail:
-       btrfs_block_rsv_release(root, &pending->block_rsv, (u64)-1);
        return ret;
 }
 

diff --git a/fs/btrfs/transaction.h b/fs/btrfs/transaction.h
index 5f67fba..3c8e0d2 100644 (file)
--- a/fs/btrfs/transaction.h
+++ b/fs/btrfs/transaction.h
@@ -90,6 +90,7 @@ struct btrfs_pending_snapshot {
        struct btrfs_qgroup_inherit *inherit;
        /* block reservation for the operation */
        struct btrfs_block_rsv block_rsv;
+       u64 qgroup_reserved;
        /* extra metadata reseration for relocation */
        int error;
        bool readonly;