[PATCH 4/5] btrfs: extent_io: Unify the return value of alloc_test_extent_buffer() with alloc_extent_buffer()

[Qu Wenruo]

The function only get called in two locations:
1) free-space-tree-tests.c
2) qgroup-tests.c
   These call sites are stubs.

3) btrfs_find_create_tree_block()
   Since all existing btrfs_find_create_tree_block() callers handles
   the return value correctly, it's also a stub.

So all alloc_test_extent_buffer() callers should be covered by this
patch.

Reported-by: Dan Carpenter <dan.carpen...@oracle.com>
Signed-off-by: Qu Wenruo <w...@suse.com>
---
 fs/btrfs/extent_io.c                   | 21 +++++++++++----------
 fs/btrfs/tests/free-space-tree-tests.c |  3 ++-
 fs/btrfs/tests/qgroup-tests.c          |  3 ++-
 3 files changed, 15 insertions(+), 12 deletions(-)

diff --git a/fs/btrfs/extent_io.c b/fs/btrfs/extent_io.c
index f9c9da9b84a3..a19bd8bc3b32 100644
--- a/fs/btrfs/extent_io.c
+++ b/fs/btrfs/extent_io.c
@@ -4863,6 +4863,7 @@ struct extent_buffer *find_extent_buffer(struct 
btrfs_fs_info *fs_info,
 }
 
 #ifdef CONFIG_BTRFS_FS_RUN_SANITY_TESTS
+/* Will either return valid pointer or PTR_ERR(), NEVER NULL pointer. */
 struct extent_buffer *alloc_test_extent_buffer(struct btrfs_fs_info *fs_info,
                                        u64 start)
 {
@@ -4874,12 +4875,14 @@ struct extent_buffer *alloc_test_extent_buffer(struct 
btrfs_fs_info *fs_info,
                return eb;
        eb = alloc_dummy_extent_buffer(fs_info, start);
        if (IS_ERR(eb))
-               return NULL;
+               return eb;
        eb->fs_info = fs_info;
 again:
        ret = radix_tree_preload(GFP_NOFS);
-       if (ret)
-               goto free_eb;
+       if (ret) {
+               btrfs_release_extent_buffer(eb);
+               return ERR_PTR(ret);
+       }
        spin_lock(&fs_info->buffer_lock);
        ret = radix_tree_insert(&fs_info->buffer_radix,
                                start >> PAGE_SHIFT, eb);
@@ -4887,18 +4890,16 @@ struct extent_buffer *alloc_test_extent_buffer(struct 
btrfs_fs_info *fs_info,
        radix_tree_preload_end();
        if (ret == -EEXIST) {
                exists = find_extent_buffer(fs_info, start);
-               if (exists)
-                       goto free_eb;
-               else
-                       goto again;
+               if (exists) {
+                       btrfs_release_extent_buffer(eb);
+                       return exists;
+               }
+               goto again;
        }
        check_buffer_tree_ref(eb);
        set_bit(EXTENT_BUFFER_IN_TREE, &eb->bflags);
 
        return eb;
-free_eb:
-       btrfs_release_extent_buffer(eb);
-       return exists;
 }
 #endif
 
diff --git a/fs/btrfs/tests/free-space-tree-tests.c 
b/fs/btrfs/tests/free-space-tree-tests.c
index 89346da890cf..025fce63959a 100644
--- a/fs/btrfs/tests/free-space-tree-tests.c
+++ b/fs/btrfs/tests/free-space-tree-tests.c
@@ -462,7 +462,8 @@ static int run_test(test_func_t test_func, int bitmaps, u32 
sectorsize,
        root->fs_info->tree_root = root;
 
        root->node = alloc_test_extent_buffer(root->fs_info, nodesize);
-       if (!root->node) {
+       if (IS_ERR(root->node)) {
+               root->node = NULL;
                test_err("couldn't allocate dummy buffer");
                ret = -ENOMEM;
                goto out;
diff --git a/fs/btrfs/tests/qgroup-tests.c b/fs/btrfs/tests/qgroup-tests.c
index 412b910b04cc..536600eb4d9d 100644
--- a/fs/btrfs/tests/qgroup-tests.c
+++ b/fs/btrfs/tests/qgroup-tests.c
@@ -484,7 +484,8 @@ int btrfs_test_qgroups(u32 sectorsize, u32 nodesize)
         * *cough*backref walking code*cough*
         */
        root->node = alloc_test_extent_buffer(root->fs_info, nodesize);
-       if (!root->node) {
+       if (IS_ERR(root->node)) {
+               root->node = NULL;
                test_err("couldn't allocate dummy buffer");
                ret = -ENOMEM;
                goto out;
-- 
2.20.1