Btrfs: Integrate metadata reservation with start_transaction

Besides simplify the code, this change makes sure all metadata
reservation for normal metadata operations are released after
committing transaction.

Changes since V1:

Add code that check if unlink and rmdir will free space.

Add ENOSPC handling for clone ioctl.

Signed-off-by: Yan Zheng <zheng.yan@oracle.com>
Signed-off-by: Chris Mason <chris.mason@oracle.com>

1 files changed, 80 insertions, 77 deletions

diff --git a/fs/btrfs/ioctl.c b/fs/btrfs/ioctl.c
index 97a97839a867..3066da468c6d 100644
--- a/fs/btrfs/ioctl.c
+++ b/fs/btrfs/ioctl.c
@@ -239,23 +239,19 @@ static noinline int create_subvol(struct btrfs_root *root,
         u64 new_dirid = BTRFS_FIRST_FREE_OBJECTID;
         u64 index = 0;
 
+        ret = btrfs_find_free_objectid(NULL, root->fs_info->tree_root,
+                                       0, &objectid);
+        if (ret)
+                return ret;
         /*
          * 1 - inode item
          * 2 - refs
          * 1 - root item
          * 2 - dir items
          */
-        ret = btrfs_reserve_metadata_space(root, 6);
-        if (ret)
-                return ret;
-
-        trans = btrfs_start_transaction(root, 1);
-        BUG_ON(!trans);
-
-        ret = btrfs_find_free_objectid(trans, root->fs_info->tree_root,
-                                       0, &objectid);
-        if (ret)
-                goto fail;
+        trans = btrfs_start_transaction(root, 6);
+        if (IS_ERR(trans))
+                return PTR_ERR(trans);
 
         leaf = btrfs_alloc_free_block(trans, root, root->leafsize,
                                       0, objectid, NULL, 0, 0, 0);
@@ -345,13 +341,10 @@ fail:
         err = btrfs_commit_transaction(trans, root);
         if (err && !ret)
                 ret = err;
-
-        btrfs_unreserve_metadata_space(root, 6);
         return ret;
 }
 
-static int create_snapshot(struct btrfs_root *root, struct dentry *dentry,
-                           char *name, int namelen)
+static int create_snapshot(struct btrfs_root *root, struct dentry *dentry)
 {
         struct inode *inode;
         struct btrfs_pending_snapshot *pending_snapshot;
@@ -361,40 +354,33 @@ static int create_snapshot(struct btrfs_root *root, struct dentry *dentry,
         if (!root->ref_cows)
                 return -EINVAL;
 
-        /*
-         * 1 - inode item
-         * 2 - refs
-         * 1 - root item
-         * 2 - dir items
-         */
-        ret = btrfs_reserve_metadata_space(root, 6);
-        if (ret)
-                goto fail;
-
         pending_snapshot = kzalloc(sizeof(*pending_snapshot), GFP_NOFS);
-        if (!pending_snapshot) {
-                ret = -ENOMEM;
-                btrfs_unreserve_metadata_space(root, 6);
-                goto fail;
-        }
-        pending_snapshot->name = kmalloc(namelen + 1, GFP_NOFS);
-        if (!pending_snapshot->name) {
-                ret = -ENOMEM;
-                kfree(pending_snapshot);
-                btrfs_unreserve_metadata_space(root, 6);
-                goto fail;
-        }
-        memcpy(pending_snapshot->name, name, namelen);
-        pending_snapshot->name[namelen] = '\0';
+        if (!pending_snapshot)
+                return -ENOMEM;
+
+        btrfs_init_block_rsv(&pending_snapshot->block_rsv);
         pending_snapshot->dentry = dentry;
-        trans = btrfs_start_transaction(root, 1);
-        BUG_ON(!trans);
         pending_snapshot->root = root;
+
+        trans = btrfs_start_transaction(root->fs_info->extent_root, 5);
+        if (IS_ERR(trans)) {
+                ret = PTR_ERR(trans);
+                goto fail;
+        }
+
+        ret = btrfs_snap_reserve_metadata(trans, pending_snapshot);
+        BUG_ON(ret);
+
         list_add(&pending_snapshot->list,
                  &trans->transaction->pending_snapshots);
-        ret = btrfs_commit_transaction(trans, root);
+        ret = btrfs_commit_transaction(trans, root->fs_info->extent_root);
         BUG_ON(ret);
-        btrfs_unreserve_metadata_space(root, 6);
+
+        ret = pending_snapshot->error;
+        if (ret)
+                goto fail;
+
+        btrfs_orphan_cleanup(pending_snapshot->snap);
 
         inode = btrfs_lookup_dentry(dentry->d_parent->d_inode, dentry);
         if (IS_ERR(inode)) {
@@ -405,6 +391,7 @@ static int create_snapshot(struct btrfs_root *root, struct dentry *dentry,
         d_instantiate(dentry, inode);
         ret = 0;
 fail:
+        kfree(pending_snapshot);
         return ret;
 }
 
@@ -456,8 +443,7 @@ static noinline int btrfs_mksubvol(struct path *parent,
                 goto out_up_read;
 
         if (snap_src) {
-                error = create_snapshot(snap_src, dentry,
-                                        name, namelen);
+                error = create_snapshot(snap_src, dentry);
         } else {
                 error = create_subvol(BTRFS_I(dir)->root, dentry,
                                       name, namelen);
@@ -811,7 +797,7 @@ static noinline int btrfs_ioctl_resize(struct btrfs_root *root,
                 device->name, (unsigned long long)new_size);
 
         if (new_size > old_size) {
-                trans = btrfs_start_transaction(root, 1);
+                trans = btrfs_start_transaction(root, 0);
                 ret = btrfs_grow_device(trans, device, new_size);
                 btrfs_commit_transaction(trans, root);
         } else {
@@ -1300,7 +1286,13 @@ static noinline int btrfs_ioctl_snap_destroy(struct file *file,
         if (err)
                 goto out_up_write;
 
-        trans = btrfs_start_transaction(root, 1);
+        trans = btrfs_start_transaction(root, 0);
+        if (IS_ERR(trans)) {
+                err = PTR_ERR(trans);
+                goto out;
+        }
+        trans->block_rsv = &root->fs_info->global_block_rsv;
+
         ret = btrfs_unlink_subvol(trans, root, dir,
                                 dest->root_key.objectid,
                                 dentry->d_name.name,
@@ -1550,12 +1542,6 @@ static noinline long btrfs_ioctl_clone(struct file *file, unsigned long srcfd,
                 btrfs_wait_ordered_range(src, off, off+len);
         }
 
-        trans = btrfs_start_transaction(root, 1);
-        BUG_ON(!trans);
-
-        /* punch hole in destination first */
-        btrfs_drop_extents(trans, inode, off, off + len, &hint_byte, 1);
-
         /* clone data */
         key.objectid = src->i_ino;
         key.type = BTRFS_EXTENT_DATA_KEY;
@@ -1566,7 +1552,7 @@ static noinline long btrfs_ioctl_clone(struct file *file, unsigned long srcfd,
                  * note the key will change type as we walk through the
                  * tree.
                  */
-                ret = btrfs_search_slot(trans, root, &key, path, 0, 0);
+                ret = btrfs_search_slot(NULL, root, &key, path, 0, 0);
                 if (ret < 0)
                         goto out;
 
@@ -1629,12 +1615,31 @@ static noinline long btrfs_ioctl_clone(struct file *file, unsigned long srcfd,
                         new_key.objectid = inode->i_ino;
                         new_key.offset = key.offset + destoff - off;
 
+                        trans = btrfs_start_transaction(root, 1);
+                        if (IS_ERR(trans)) {
+                                ret = PTR_ERR(trans);
+                                goto out;
+                        }
+
                         if (type == BTRFS_FILE_EXTENT_REG ||
                             type == BTRFS_FILE_EXTENT_PREALLOC) {
+                                if (off > key.offset) {
+                                        datao += off - key.offset;
+                                        datal -= off - key.offset;
+                                }
+
+                                if (key.offset + datal > off + len)
+                                        datal = off + len - key.offset;
+
+                                ret = btrfs_drop_extents(trans, inode,
+                                                         new_key.offset,
+                                                         new_key.offset + datal,
+                                                         &hint_byte, 1);
+                                BUG_ON(ret);
+
                                 ret = btrfs_insert_empty_item(trans, root, path,
                                                               &new_key, size);
-                                if (ret)
-                                        goto out;
+                                BUG_ON(ret);
 
                                 leaf = path->nodes[0];
                                 slot = path->slots[0];
@@ -1645,14 +1650,6 @@ static noinline long btrfs_ioctl_clone(struct file *file, unsigned long srcfd,
                                 extent = btrfs_item_ptr(leaf, slot,
                                                 struct btrfs_file_extent_item);
 
-                                if (off > key.offset) {
-                                        datao += off - key.offset;
-                                        datal -= off - key.offset;
-                                }
-
-                                if (key.offset + datal > off + len)
-                                        datal = off + len - key.offset;
-
                                 /* disko == 0 means it's a hole */
                                 if (!disko)
                                         datao = 0;
@@ -1683,14 +1680,21 @@ static noinline long btrfs_ioctl_clone(struct file *file, unsigned long srcfd,
 
                                 if (comp && (skip || trim)) {
                                         ret = -EINVAL;
+                                        btrfs_end_transaction(trans, root);
                                         goto out;
                                 }
                                 size -= skip + trim;
                                 datal -= skip + trim;
+
+                                ret = btrfs_drop_extents(trans, inode,
+                                                         new_key.offset,
+                                                         new_key.offset + datal,
+                                                         &hint_byte, 1);
+                                BUG_ON(ret);
+
                                 ret = btrfs_insert_empty_item(trans, root, path,
                                                               &new_key, size);
-                                if (ret)
-                                        goto out;
+                                BUG_ON(ret);
 
                                 if (skip) {
                                         u32 start =
@@ -1708,8 +1712,17 @@ static noinline long btrfs_ioctl_clone(struct file *file, unsigned long srcfd,
                         }
 
                         btrfs_mark_buffer_dirty(leaf);
-                }
+                        btrfs_release_path(root, path);
 
+                        inode->i_mtime = inode->i_ctime = CURRENT_TIME;
+                        if (new_key.offset + datal > inode->i_size)
+                                btrfs_i_size_write(inode,
+                                                   new_key.offset + datal);
+                        BTRFS_I(inode)->flags = BTRFS_I(src)->flags;
+                        ret = btrfs_update_inode(trans, root, inode);
+                        BUG_ON(ret);
+                        btrfs_end_transaction(trans, root);
+                }
 next:
                 btrfs_release_path(root, path);
                 key.offset++;
@@ -1717,17 +1730,7 @@ next:
         ret = 0;
 out:
         btrfs_release_path(root, path);
-        if (ret == 0) {
-                inode->i_mtime = inode->i_ctime = CURRENT_TIME;
-                if (destoff + olen > inode->i_size)
-                        btrfs_i_size_write(inode, destoff + olen);
-                BTRFS_I(inode)->flags = BTRFS_I(src)->flags;
-                ret = btrfs_update_inode(trans, root, inode);
-        }
-        btrfs_end_transaction(trans, root);
         unlock_extent(&BTRFS_I(src)->io_tree, off, off+len, GFP_NOFS);
-        if (ret)
-                vmtruncate(inode, 0);
 out_unlock:
         mutex_unlock(&src->i_mutex);
         mutex_unlock(&inode->i_mutex);