[v2] btrfs: Fix btrfs_find_create_tree_block() testing
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Message ID 20191203112457.GF1787@kadam
State New
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  • [v2] btrfs: Fix btrfs_find_create_tree_block() testing
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Commit Message

Dan Carpenter Dec. 3, 2019, 11:24 a.m. UTC
The btrfs_find_create_tree_block() uses alloc_test_extent_buffer() for
testing and alloc_extent_buffer() for production.  The problem is that
the test code returns NULL and the production code returns error
pointers.  The callers only check for error pointers.

I have changed alloc_test_extent_buffer() to return error pointers and
updated the two callers which use it directly.

Fixes: faa2dbf004e8 ("Btrfs: add sanity tests for new qgroup accounting code")
Signed-off-by: Dan Carpenter <dan.carpenter@oracle.com>
---
v2: Correct the commit message.  alloc_test_extent_buffer() instead of
alloc_dummy_extent_buffer().

 fs/btrfs/extent_io.c                   | 6 ++++--
 fs/btrfs/tests/free-space-tree-tests.c | 4 ++--
 fs/btrfs/tests/qgroup-tests.c          | 4 ++--
 3 files changed, 8 insertions(+), 6 deletions(-)

Comments

David Sterba Dec. 3, 2019, 6:40 p.m. UTC | #1
On Tue, Dec 03, 2019 at 02:24:58PM +0300, Dan Carpenter wrote:
> The btrfs_find_create_tree_block() uses alloc_test_extent_buffer() for
> testing and alloc_extent_buffer() for production.  The problem is that
> the test code returns NULL and the production code returns error
> pointers.  The callers only check for error pointers.
> 
> I have changed alloc_test_extent_buffer() to return error pointers and
> updated the two callers which use it directly.
> 
> Fixes: faa2dbf004e8 ("Btrfs: add sanity tests for new qgroup accounting code")
> Signed-off-by: Dan Carpenter <dan.carpenter@oracle.com>

I edited the changelog because btrfs_find_create_tree_block is
misleading and seems to be unrelated to the actual fix that's just for
alloc_test_extent_buffer. Patch added to misc-next, thanks.
Dan Carpenter Dec. 3, 2019, 6:46 p.m. UTC | #2
On Tue, Dec 03, 2019 at 07:40:39PM +0100, David Sterba wrote:
> On Tue, Dec 03, 2019 at 02:24:58PM +0300, Dan Carpenter wrote:
> > The btrfs_find_create_tree_block() uses alloc_test_extent_buffer() for
> > testing and alloc_extent_buffer() for production.  The problem is that
> > the test code returns NULL and the production code returns error
> > pointers.  The callers only check for error pointers.
> > 
> > I have changed alloc_test_extent_buffer() to return error pointers and
> > updated the two callers which use it directly.
> > 
> > Fixes: faa2dbf004e8 ("Btrfs: add sanity tests for new qgroup accounting code")
> > Signed-off-by: Dan Carpenter <dan.carpenter@oracle.com>
> 
> I edited the changelog because btrfs_find_create_tree_block is
> misleading and seems to be unrelated to the actual fix that's just for
> alloc_test_extent_buffer. Patch added to misc-next, thanks.

The bug is in btrfs_find_create_tree_block()

fs/btrfs/disk-io.c
  1046  struct extent_buffer *btrfs_find_create_tree_block(
  1047                                                  struct btrfs_fs_info *fs_info,
  1048                                                  u64 bytenr)
  1049  {
  1050          if (btrfs_is_testing(fs_info))
  1051                  return alloc_test_extent_buffer(fs_info, bytenr);
                        ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
NULL

  1052          return alloc_extent_buffer(fs_info, bytenr);
                ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
Error pointers.

  1053  }

None of the callers of btrfs_find_create_tree_block() check for NULL.

regards,
dan carpenter
David Sterba Dec. 3, 2019, 7:06 p.m. UTC | #3
On Tue, Dec 03, 2019 at 09:46:01PM +0300, Dan Carpenter wrote:
> On Tue, Dec 03, 2019 at 07:40:39PM +0100, David Sterba wrote:
> > On Tue, Dec 03, 2019 at 02:24:58PM +0300, Dan Carpenter wrote:
> > > The btrfs_find_create_tree_block() uses alloc_test_extent_buffer() for
> > > testing and alloc_extent_buffer() for production.  The problem is that
> > > the test code returns NULL and the production code returns error
> > > pointers.  The callers only check for error pointers.
> > > 
> > > I have changed alloc_test_extent_buffer() to return error pointers and
> > > updated the two callers which use it directly.
> > > 
> > > Fixes: faa2dbf004e8 ("Btrfs: add sanity tests for new qgroup accounting code")
> > > Signed-off-by: Dan Carpenter <dan.carpenter@oracle.com>
> > 
> > I edited the changelog because btrfs_find_create_tree_block is
> > misleading and seems to be unrelated to the actual fix that's just for
> > alloc_test_extent_buffer. Patch added to misc-next, thanks.
> 
> The bug is in btrfs_find_create_tree_block()
> 
> fs/btrfs/disk-io.c
>   1046  struct extent_buffer *btrfs_find_create_tree_block(
>   1047                                                  struct btrfs_fs_info *fs_info,
>   1048                                                  u64 bytenr)
>   1049  {
>   1050          if (btrfs_is_testing(fs_info))
>   1051                  return alloc_test_extent_buffer(fs_info, bytenr);
>                         ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
> NULL
> 
>   1052          return alloc_extent_buffer(fs_info, bytenr);
>                 ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
> Error pointers.
> 
>   1053  }
> 
> None of the callers of btrfs_find_create_tree_block() check for NULL.

I see, though my view is a bug in alloc_test_extent_buffer that should
follow alloc_extent_buffer semantics, and this gets fixed. I'll update
the changelog again, makes sense to mention that it namely affects
btrfs_find_create_tree_block.

Patch
diff mbox series

diff --git a/fs/btrfs/extent_io.c b/fs/btrfs/extent_io.c
index eb8bd0258360..2f4802f405a2 100644
--- a/fs/btrfs/extent_io.c
+++ b/fs/btrfs/extent_io.c
@@ -5074,12 +5074,14 @@  struct extent_buffer *alloc_test_extent_buffer(struct btrfs_fs_info *fs_info,
 		return eb;
 	eb = alloc_dummy_extent_buffer(fs_info, start);
 	if (!eb)
-		return NULL;
+		return ERR_PTR(-ENOMEM);
 	eb->fs_info = fs_info;
 again:
 	ret = radix_tree_preload(GFP_NOFS);
-	if (ret)
+	if (ret) {
+		exists = ERR_PTR(ret);
 		goto free_eb;
+	}
 	spin_lock(&fs_info->buffer_lock);
 	ret = radix_tree_insert(&fs_info->buffer_radix,
 				start >> PAGE_SHIFT, eb);
diff --git a/fs/btrfs/tests/free-space-tree-tests.c b/fs/btrfs/tests/free-space-tree-tests.c
index 1a846bf6e197..914eea5ba6a7 100644
--- a/fs/btrfs/tests/free-space-tree-tests.c
+++ b/fs/btrfs/tests/free-space-tree-tests.c
@@ -452,9 +452,9 @@  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)) {
 		test_std_err(TEST_ALLOC_EXTENT_BUFFER);
-		ret = -ENOMEM;
+		ret = PTR_ERR(root->node);
 		goto out;
 	}
 	btrfs_set_header_level(root->node, 0);
diff --git a/fs/btrfs/tests/qgroup-tests.c b/fs/btrfs/tests/qgroup-tests.c
index 09aaca1efd62..ac035a6fa003 100644
--- a/fs/btrfs/tests/qgroup-tests.c
+++ b/fs/btrfs/tests/qgroup-tests.c
@@ -484,9 +484,9 @@  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)) {
 		test_err("couldn't allocate dummy buffer");
-		ret = -ENOMEM;
+		ret = PTR_ERR(root->node);
 		goto out;
 	}
 	btrfs_set_header_level(root->node, 0);