linux-kernel - [PATCH] cachefiles: fix __cachefiles_prepare

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Message-Id: <20211204220350.633811-1-arnd@kernel.org>
Date:   Sat,  4 Dec 2021 23:03:16 +0100
From:   Arnd Bergmann <arnd@...nel.org>
To:     David Howells <dhowells@...hat.com>
Cc:     Arnd Bergmann <arnd@...db.de>,
        Nathan Chancellor <nathan@...nel.org>,
        Nick Desaulniers <ndesaulniers@...gle.com>,
        Jeff Layton <jlayton@...nel.org>, linux-cachefs@...hat.com,
        linux-kernel@...r.kernel.org, llvm@...ts.linux.dev
Subject: [PATCH] cachefiles: fix __cachefiles_prepare_write() error handling

From: Arnd Bergmann <arnd@...db.de>

clang points out that __cachefiles_prepare_write() returns an
uninitialized error code in one of the code paths:

fs/cachefiles/io.c:489:6: error: variable 'ret' is used uninitialized whenever 'if' condition is false [-Werror,-Wsometimes-uninitialized]
        if (pos == 0)
            ^~~~~~~~
fs/cachefiles/io.c:492:6: note: uninitialized use occurs here
        if (ret < 0) {
            ^~~
fs/cachefiles/io.c:489:2: note: remove the 'if' if its condition is always true
        if (pos == 0)
        ^~~~~~~~~~~~~
fs/cachefiles/io.c:440:9: note: initialize the variable 'ret' to silence this warning
        int ret;
               ^

Rework to return zero for success here and skip the rest of the
function.

Fixes: 0443b01eccbb ("cachefiles: Implement the I/O routines")
Signed-off-by: Arnd Bergmann <arnd@...db.de>
---
 fs/cachefiles/io.c | 8 +++++---
 1 file changed, 5 insertions(+), 3 deletions(-)

diff --git a/fs/cachefiles/io.c b/fs/cachefiles/io.c
index 74ef4d1fc562..0fab313a604d 100644
--- a/fs/cachefiles/io.c
+++ b/fs/cachefiles/io.c
@@ -486,9 +486,11 @@ static int __cachefiles_prepare_write(struct netfs_cache_resources *cres,
 	/* Partially allocated, but insufficient space: cull. */
 	fscache_count_no_write_space();
 	pos = cachefiles_inject_remove_error();
-	if (pos == 0)
-		ret = vfs_fallocate(file, FALLOC_FL_PUNCH_HOLE | FALLOC_FL_KEEP_SIZE,
-				    *_start, *_len);
+	if (pos != 0)
+		return 0;
+
+	ret = vfs_fallocate(file, FALLOC_FL_PUNCH_HOLE | FALLOC_FL_KEEP_SIZE,
+			    *_start, *_len);
 	if (ret < 0) {
 		trace_cachefiles_io_error(object, file_inode(file), ret,
 					  cachefiles_trace_fallocate_error);
-- 
2.29.2