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, 90 insertions, 41 deletions

diff --git a/fs/btrfs/transaction.c b/fs/btrfs/transaction.c
index 21ad37c05199..2616491a5c5b 100644
--- a/fs/btrfs/transaction.c
+++ b/fs/btrfs/transaction.c
@@ -165,53 +165,89 @@ enum btrfs_trans_type {
         TRANS_USERSPACE,
 };
 
+static int may_wait_transaction(struct btrfs_root *root, int type)
+{
+        if (!root->fs_info->log_root_recovering &&
+            ((type == TRANS_START && !root->fs_info->open_ioctl_trans) ||
+             type == TRANS_USERSPACE))
+                return 1;
+        return 0;
+}
+
 static struct btrfs_trans_handle *start_transaction(struct btrfs_root *root,
-                                             int num_blocks, int type)
+                                                    u64 num_items, int type)
 {
-        struct btrfs_trans_handle *h =
-                kmem_cache_alloc(btrfs_trans_handle_cachep, GFP_NOFS);
+        struct btrfs_trans_handle *h;
+        struct btrfs_transaction *cur_trans;
+        int retries = 0;
         int ret;
+again:
+        h = kmem_cache_alloc(btrfs_trans_handle_cachep, GFP_NOFS);
+        if (!h)
+                return ERR_PTR(-ENOMEM);
 
         mutex_lock(&root->fs_info->trans_mutex);
-        if (!root->fs_info->log_root_recovering &&
-            ((type == TRANS_START && !root->fs_info->open_ioctl_trans) ||
-             type == TRANS_USERSPACE))
+        if (may_wait_transaction(root, type))
                 wait_current_trans(root);
+
         ret = join_transaction(root);
         BUG_ON(ret);
 
-        h->transid = root->fs_info->running_transaction->transid;
-        h->transaction = root->fs_info->running_transaction;
-        h->blocks_reserved = num_blocks;
+        cur_trans = root->fs_info->running_transaction;
+        cur_trans->use_count++;
+        mutex_unlock(&root->fs_info->trans_mutex);
+
+        h->transid = cur_trans->transid;
+        h->transaction = cur_trans;
         h->blocks_used = 0;
         h->block_group = 0;
+        h->bytes_reserved = 0;
         h->delayed_ref_updates = 0;
         h->block_rsv = NULL;
 
-        if (!current->journal_info && type != TRANS_USERSPACE)
-                current->journal_info = h;
+        smp_mb();
+        if (cur_trans->blocked && may_wait_transaction(root, type)) {
+                btrfs_commit_transaction(h, root);
+                goto again;
+        }
+
+        if (num_items > 0) {
+                ret = btrfs_trans_reserve_metadata(h, root, num_items,
+                                                   &retries);
+                if (ret == -EAGAIN) {
+                        btrfs_commit_transaction(h, root);
+                        goto again;
+                }
+                if (ret < 0) {
+                        btrfs_end_transaction(h, root);
+                        return ERR_PTR(ret);
+                }
+        }
 
-        root->fs_info->running_transaction->use_count++;
+        mutex_lock(&root->fs_info->trans_mutex);
         record_root_in_trans(h, root);
         mutex_unlock(&root->fs_info->trans_mutex);
+
+        if (!current->journal_info && type != TRANS_USERSPACE)
+                current->journal_info = h;
         return h;
 }
 
 struct btrfs_trans_handle *btrfs_start_transaction(struct btrfs_root *root,
-                                                   int num_blocks)
+                                                   int num_items)
 {
-        return start_transaction(root, num_blocks, TRANS_START);
+        return start_transaction(root, num_items, TRANS_START);
 }
 struct btrfs_trans_handle *btrfs_join_transaction(struct btrfs_root *root,
                                                    int num_blocks)
 {
-        return start_transaction(root, num_blocks, TRANS_JOIN);
+        return start_transaction(root, 0, TRANS_JOIN);
 }
 
 struct btrfs_trans_handle *btrfs_start_ioctl_transaction(struct btrfs_root *r,
                                                          int num_blocks)
 {
-        return start_transaction(r, num_blocks, TRANS_USERSPACE);
+        return start_transaction(r, 0, TRANS_USERSPACE);
 }
 
 /* wait for a transaction commit to be fully complete */
@@ -312,6 +348,8 @@ static int __btrfs_end_transaction(struct btrfs_trans_handle *trans,
                 count++;
         }
 
+        btrfs_trans_release_metadata(trans, root);
+
         mutex_lock(&info->trans_mutex);
         cur_trans = info->running_transaction;
         WARN_ON(cur_trans != trans->transaction);
@@ -757,47 +795,49 @@ static noinline int create_pending_snapshot(struct btrfs_trans_handle *trans,
         struct btrfs_root *root = pending->root;
         struct btrfs_root *parent_root;
         struct inode *parent_inode;
+        struct dentry *dentry;
         struct extent_buffer *tmp;
         struct extent_buffer *old;
         int ret;
-        u64 objectid;
-        int namelen;
         u64 index = 0;
-
-        parent_inode = pending->dentry->d_parent->d_inode;
-        parent_root = BTRFS_I(parent_inode)->root;
+        u64 objectid;
 
         new_root_item = kmalloc(sizeof(*new_root_item), GFP_NOFS);
         if (!new_root_item) {
-                ret = -ENOMEM;
+                pending->error = -ENOMEM;
                 goto fail;
         }
+
         ret = btrfs_find_free_objectid(trans, tree_root, 0, &objectid);
-        if (ret)
+        if (ret) {
+                pending->error = ret;
                 goto fail;
+        }
 
         key.objectid = objectid;
-        /* record when the snapshot was created in key.offset */
-        key.offset = trans->transid;
-        btrfs_set_key_type(&key, BTRFS_ROOT_ITEM_KEY);
+        key.offset = (u64)-1;
+        key.type = BTRFS_ROOT_ITEM_KEY;
 
-        memcpy(&pending->root_key, &key, sizeof(key));
-        pending->root_key.offset = (u64)-1;
+        trans->block_rsv = &pending->block_rsv;
 
+        dentry = pending->dentry;
+        parent_inode = dentry->d_parent->d_inode;
+        parent_root = BTRFS_I(parent_inode)->root;
         record_root_in_trans(trans, parent_root);
+
         /*
          * insert the directory item
          */
-        namelen = strlen(pending->name);
         ret = btrfs_set_inode_index(parent_inode, &index);
         BUG_ON(ret);
         ret = btrfs_insert_dir_item(trans, parent_root,
-                            pending->name, namelen,
-                            parent_inode->i_ino,
-                            &pending->root_key, BTRFS_FT_DIR, index);
+                                dentry->d_name.name, dentry->d_name.len,
+                                parent_inode->i_ino, &key,
+                                BTRFS_FT_DIR, index);
         BUG_ON(ret);
 
-        btrfs_i_size_write(parent_inode, parent_inode->i_size + namelen * 2);
+        btrfs_i_size_write(parent_inode, parent_inode->i_size +
+                                         dentry->d_name.len * 2);
         ret = btrfs_update_inode(trans, parent_root, parent_inode);
         BUG_ON(ret);
 
@@ -814,22 +854,29 @@ static noinline int create_pending_snapshot(struct btrfs_trans_handle *trans,
         free_extent_buffer(old);
 
         btrfs_set_root_node(new_root_item, tmp);
-        ret = btrfs_insert_root(trans, root->fs_info->tree_root, &key,
-                                new_root_item);
-        BUG_ON(ret);
+        /* record when the snapshot was created in key.offset */
+        key.offset = trans->transid;
+        ret = btrfs_insert_root(trans, tree_root, &key, new_root_item);
         btrfs_tree_unlock(tmp);
         free_extent_buffer(tmp);
+        BUG_ON(ret);
 
-        ret = btrfs_add_root_ref(trans, parent_root->fs_info->tree_root,
-                                 pending->root_key.objectid,
+        /*
+         * insert root back/forward references
+         */
+        ret = btrfs_add_root_ref(trans, tree_root, objectid,
                                  parent_root->root_key.objectid,
-                                 parent_inode->i_ino, index, pending->name,
-                                 namelen);
+                                 parent_inode->i_ino, index,
+                                 dentry->d_name.name, dentry->d_name.len);
         BUG_ON(ret);
 
+        key.offset = (u64)-1;
+        pending->snap = btrfs_read_fs_root_no_name(root->fs_info, &key);
+        BUG_ON(IS_ERR(pending->snap));
 fail:
         kfree(new_root_item);
-        return ret;
+        btrfs_block_rsv_release(root, &pending->block_rsv, (u64)-1);
+        return 0;
 }
 
 /*
@@ -898,6 +945,8 @@ int btrfs_commit_transaction(struct btrfs_trans_handle *trans,
         ret = btrfs_run_delayed_refs(trans, root, 0);
         BUG_ON(ret);
 
+        btrfs_trans_release_metadata(trans, root);
+
         cur_trans = trans->transaction;
         /*
          * set the flushing flag so procs in this transaction have to