btrfs: fix compiler warning on SPARC/PA-RISC handling fscrypt_setup_filename

Commit 1ec49744ba83 ("btrfs: turn on -Wmaybe-uninitialized") exposed
that on SPARC and PA-RISC, gcc is unaware that fscrypt_setup_filename()
only returns negative error values or 0. This ultimately results in a
maybe-uninitialized warning in btrfs_lookup_dentry().

Change to only return negative error values or 0 from
fscrypt_setup_filename() at the relevant call site, and assert that no
positive error codes are returned (which would have wider implications
involving other users).

Reported-by: Guenter Roeck <linux@roeck-us.net>
Link: https://lore.kernel.org/all/481b19b5-83a0-4793-b4fd-194ad7b978c3@roeck-us.net/
Signed-off-by: Sweet Tea Dorminy <sweettea-kernel@dorminy.me>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>

diff --git a/fs/btrfs/inode.c b/fs/btrfs/inode.c
index 44e9acc..e99432e 100644 (file)
--- a/fs/btrfs/inode.c
+++ b/fs/btrfs/inode.c
@@ -5421,8 +5421,13 @@ static int btrfs_inode_by_name(struct btrfs_inode *dir, struct dentry *dentry,
                return -ENOMEM;
 
        ret = fscrypt_setup_filename(&dir->vfs_inode, &dentry->d_name, 1, &fname);
-       if (ret)
+       if (ret < 0)
                goto out;
+       /*
+        * fscrypt_setup_filename() should never return a positive value, but
+        * gcc on sparc/parisc thinks it can, so assert that doesn't happen.
+        */
+       ASSERT(ret == 0);
 
        /* This needs to handle no-key deletions later on */