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btrfs-progs: remove an unnecessary branch to silent the clang warning

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[FALSE ALERT]
With clang 15.0.7, there is a false alert on uninitialized value in
ctree.c:

  kernel-shared/ctree.c:3418:13: warning: variable 'offset' is used uninitialized whenever 'if' condition is false [-Wsometimes-uninitialized]
          } else if (ret < 0) {
                     ^~~~~~~
  kernel-shared/ctree.c:3428:41: note: uninitialized use occurs here
          write_extent_buffer(eb, &subvol_id_le, offset, sizeof(subvol_id_le));
                                                 ^~~~~~
  kernel-shared/ctree.c:3418:9: note: remove the 'if' if its condition is always true
          } else if (ret < 0) {
                 ^~~~~~~~~~~~~
  kernel-shared/ctree.c:3380:22: note: initialize the variable 'offset' to silence this warning
          unsigned long offset;
                              ^
                               = 0
  kernel-shared/ctree.c:3418:13: warning: variable 'eb' is used uninitialized whenever 'if' condition is false [-Wsometimes-uninitialized]
          } else if (ret < 0) {
                     ^~~~~~~
  kernel-shared/ctree.c:3429:26: note: uninitialized use occurs here
          btrfs_mark_buffer_dirty(eb);
                                  ^~
  kernel-shared/ctree.c:3418:9: note: remove the 'if' if its condition is always true
          } else if (ret < 0) {
                 ^~~~~~~~~~~~~
  kernel-shared/ctree.c:3378:26: note: initialize the variable 'eb' to silence this warning
          struct extent_buffer *eb;
                                  ^
                                   = NULL

[CAUSE]
The original code is handling the return value from
btrfs_insert_empty_item() like this:

	ret = btrfs_insert_empty_item();
	if (ret >= 0) {
		/* Do something for it. */
	} else if (ret == -EEXIST) {
		/* Do something else. */
	} else if (ret < 0) {
		/* Error handling. */
	}

But the problem is, the last one check is always true if we can reach
there.

Thus clang is providing the hint to remove the if () check.

[FIX]
Normally we prefer to do error handling first, so move the error
handling first so we don't need the if () else if () chain.

Signed-off-by: Qu Wenruo <wqu@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
This commit is contained in:
Qu Wenruo 2023-01-27 13:41:14 +08:00 committed by David Sterba
parent e3209f8792
commit e2806fd624
1 changed files with 10 additions and 8 deletions
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18
kernel-shared/ctree.c
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@ -3400,14 +3400,22 @@ int btrfs_uuid_tree_add(struct btrfs_trans_handle *trans, u8 *uuid, u8 type,
ret = btrfs_insert_empty_item(trans, uuid_root, path, &key,
sizeof(subvol_id_le));
if (ret < 0 && ret != -EEXIST) {
warning(
"inserting uuid item failed (0x%016llx, 0x%016llx) type %u: %d",
(unsigned long long)key.objectid,
(unsigned long long)key.offset, type, ret);
goto out;
}
if (ret >= 0) {
/* Add an item for the type for the first time */
eb = path->nodes[0];
slot = path->slots[0];
offset = btrfs_item_ptr_offset(eb, slot);
} else if (ret == -EEXIST) {
} else {
/*
* An item with that type already exists.
* ret == -EEXIST case, An item with that type already exists.
* Extend the item and store the new subvol_id at the end.
*/
btrfs_extend_item(uuid_root, path, sizeof(subvol_id_le));
@ -3415,12 +3423,6 @@ int btrfs_uuid_tree_add(struct btrfs_trans_handle *trans, u8 *uuid, u8 type,
slot = path->slots[0];
offset = btrfs_item_ptr_offset(eb, slot);
offset += btrfs_item_size(eb, slot) - sizeof(subvol_id_le);
} else if (ret < 0) {
warning(
"inserting uuid item failed (0x%016llx, 0x%016llx) type %u: %d",
(unsigned long long)key.objectid,
(unsigned long long)key.offset, type, ret);
goto out;
}
ret = 0;