btrfs: use on-stack variable for block reserve in btrfs_evict_inode()

We can avoid potential memory allocation failure in btrfs_evict_inode()
as the block reserve lifetime is limited to the scope of the function.
This requires +48 bytes on stack.

Signed-off-by: David Sterba <dsterba@suse.com>

diff --git a/fs/btrfs/inode.c b/fs/btrfs/inode.c
index b66eee5ab5d851e117429a428bd4bbd28b4875be..868c9dba16d4600f45709940a4618c6dcd234c80 100644 (file)
--- a/fs/btrfs/inode.c
+++ b/fs/btrfs/inode.c
@@ -5435,7 +5435,7 @@ void btrfs_evict_inode(struct inode *inode)
        struct btrfs_fs_info *fs_info;
        struct btrfs_trans_handle *trans;
        struct btrfs_root *root = BTRFS_I(inode)->root;
-       struct btrfs_block_rsv *rsv = NULL;
+       struct btrfs_block_rsv rsv;
        int ret;
 
        trace_btrfs_inode_evict(inode);
@@ -5483,11 +5483,9 @@ void btrfs_evict_inode(struct inode *inode)
         */
        btrfs_kill_delayed_inode_items(BTRFS_I(inode));
 
-       rsv = btrfs_alloc_block_rsv(fs_info, BTRFS_BLOCK_RSV_TEMP);
-       if (!rsv)
-               goto out;
-       rsv->size = btrfs_calc_metadata_size(fs_info, 1);
-       rsv->failfast = true;
+       btrfs_init_metadata_block_rsv(fs_info, &rsv, BTRFS_BLOCK_RSV_TEMP);
+       rsv.size = btrfs_calc_metadata_size(fs_info, 1);
+       rsv.failfast = true;
 
        btrfs_i_size_write(BTRFS_I(inode), 0);
 
@@ -5499,11 +5497,11 @@ void btrfs_evict_inode(struct inode *inode)
                        .min_type = 0,
                };
 
-               trans = evict_refill_and_join(root, rsv);
+               trans = evict_refill_and_join(root, &rsv);
                if (IS_ERR(trans))
-                       goto out;
+                       goto out_release;
 
-               trans->block_rsv = rsv;
+               trans->block_rsv = &rsv;
 
                ret = btrfs_truncate_inode_items(trans, root, &control);
                trans->block_rsv = &fs_info->trans_block_rsv;
@@ -5515,7 +5513,7 @@ void btrfs_evict_inode(struct inode *inode)
                 */
                btrfs_btree_balance_dirty_nodelay(fs_info);
                if (ret && ret != -ENOSPC && ret != -EAGAIN)
-                       goto out;
+                       goto out_release;
                else if (!ret)
                        break;
        }
@@ -5529,16 +5527,17 @@ void btrfs_evict_inode(struct inode *inode)
         * If it turns out that we are dropping too many of these, we might want
         * to add a mechanism for retrying these after a commit.
         */
-       trans = evict_refill_and_join(root, rsv);
+       trans = evict_refill_and_join(root, &rsv);
        if (!IS_ERR(trans)) {
-               trans->block_rsv = rsv;
+               trans->block_rsv = &rsv;
                btrfs_orphan_del(trans, BTRFS_I(inode));
                trans->block_rsv = &fs_info->trans_block_rsv;
                btrfs_end_transaction(trans);
        }
 
+out_release:
+       btrfs_block_rsv_release(fs_info, &rsv, (u64)-1, NULL);
 out:
-       btrfs_free_block_rsv(fs_info, rsv);
        /*
         * If we didn't successfully delete, the orphan item will still be in
         * the tree and we'll retry on the next mount. Again, we might also want