cachefiles: Clean up in cachefiles_commit_tmpfile()

Currently, cachefiles_commit_tmpfile() will only be called if object->flags
is set to CACHEFILES_OBJECT_USING_TMPFILE. Only cachefiles_create_file()
and cachefiles_invalidate_cookie() set this flag. Both of these functions
replace object->file with the new tmpfile, and both are called by
fscache_cookie_state_machine(), so there are no concurrency issues.

So the equation "d_backing_inode(dentry) == file_inode(object->file)" in
cachefiles_commit_tmpfile() will never hold true according to the above
conditions. This patch removes this part of the redundant code and does not
involve any other logical changes.

Signed-off-by: Zizhi Wo <wozizhi@huawei.com>
Link: https://lore.kernel.org/r/20241107110649.3980193-4-wozizhi@huawei.com
Acked-by: David Howells <dhowells@redhat.com>
Signed-off-by: Christian Brauner <brauner@kernel.org>

Author: Zizhi Wo

fs/cachefiles/namei.c

@@ -691,11 +691,6 @@ bool cachefiles_commit_tmpfile(struct cachefiles_cache *cache,
 	}
 
 	if (!d_is_negative(dentry)) {
-		if (d_backing_inode(dentry) == file_inode(object->file)) {
-			success = true;
-			goto out_dput;
-		}
-
 		ret = cachefiles_unlink(volume->cache, object, fan, dentry,
 					FSCACHE_OBJECT_IS_STALE);
 		if (ret < 0)