fs/jfs/jfs_dtree.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-)
From: Arnd Bergmann <arnd@arndb.de>
A recent change for the range check started triggering a clang warning:
fs/jfs/jfs_dtree.c:2906:31: error: result of comparison of constant 128 with expression of type 's8' (aka 'signed char') is always false [-Werror,-Wtautological-constant-out-of-range-compare]
2906 | if (stbl[i] < 0 || stbl[i] >= DTPAGEMAXSLOT) {
| ~~~~~~~ ^ ~~~~~~~~~~~~~
fs/jfs/jfs_dtree.c:3111:30: error: result of comparison of constant 128 with expression of type 's8' (aka 'signed char') is always false [-Werror,-Wtautological-constant-out-of-range-compare]
3111 | if (stbl[0] < 0 || stbl[0] >= DTPAGEMAXSLOT) {
| ~~~~~~~ ^ ~~~~~~~~~~~~~
Both the old and the new check were useless, but the previous version
apparently did not lead to the warning.
Rephrase this again by adding a cast. The check is still always false,
but the compiler shuts up about it.
Fixes: cafc6679824a ("jfs: replace hardcoded magic number with DTPAGEMAXSLOT constant")
Signed-off-by: Arnd Bergmann <arnd@arndb.de>
---
fs/jfs/jfs_dtree.c | 4 ++--
1 file changed, 2 insertions(+), 2 deletions(-)
diff --git a/fs/jfs/jfs_dtree.c b/fs/jfs/jfs_dtree.c
index 0ab83bb7bbdf..e3301e5fa037 100644
--- a/fs/jfs/jfs_dtree.c
+++ b/fs/jfs/jfs_dtree.c
@@ -2903,7 +2903,7 @@ int jfs_readdir(struct file *file, struct dir_context *ctx)
stbl = DT_GETSTBL(p);
for (i = index; i < p->header.nextindex; i++) {
- if (stbl[i] < 0 || stbl[i] >= DTPAGEMAXSLOT) {
+ if (stbl[i] < 0 || (unsigned char)stbl[i] >= DTPAGEMAXSLOT) {
jfs_err("JFS: Invalid stbl[%d] = %d for inode %ld, block = %lld",
i, stbl[i], (long)ip->i_ino, (long long)bn);
free_page(dirent_buf);
@@ -3108,7 +3108,7 @@ static int dtReadFirst(struct inode *ip, struct btstack * btstack)
/* get the leftmost entry */
stbl = DT_GETSTBL(p);
- if (stbl[0] < 0 || stbl[0] >= DTPAGEMAXSLOT) {
+ if (stbl[0] < 0 || (unsigned char)stbl[0] >= DTPAGEMAXSLOT) {
DT_PUTPAGE(mp);
jfs_error(ip->i_sb, "stbl[0] out of bound\n");
return -EIO;
--
2.39.5On 2/2/26 3:49AM, Arnd Bergmann wrote:
> From: Arnd Bergmann <arnd@arndb.de>
>
> A recent change for the range check started triggering a clang warning:
>
> fs/jfs/jfs_dtree.c:2906:31: error: result of comparison of constant 128 with expression of type 's8' (aka 'signed char') is always false [-Werror,-Wtautological-constant-out-of-range-compare]
> 2906 | if (stbl[i] < 0 || stbl[i] >= DTPAGEMAXSLOT) {
> | ~~~~~~~ ^ ~~~~~~~~~~~~~
> fs/jfs/jfs_dtree.c:3111:30: error: result of comparison of constant 128 with expression of type 's8' (aka 'signed char') is always false [-Werror,-Wtautological-constant-out-of-range-compare]
> 3111 | if (stbl[0] < 0 || stbl[0] >= DTPAGEMAXSLOT) {
> | ~~~~~~~ ^ ~~~~~~~~~~~~~
>
> Both the old and the new check were useless, but the previous version
> apparently did not lead to the warning.
>
> Rephrase this again by adding a cast. The check is still always false,
> but the compiler shuts up about it.
I think it would be better to just drop the useless part of these tests.
Shaggy
>
> Fixes: cafc6679824a ("jfs: replace hardcoded magic number with DTPAGEMAXSLOT constant")
> Signed-off-by: Arnd Bergmann <arnd@arndb.de>
> ---
> fs/jfs/jfs_dtree.c | 4 ++--
> 1 file changed, 2 insertions(+), 2 deletions(-)
>
> diff --git a/fs/jfs/jfs_dtree.c b/fs/jfs/jfs_dtree.c
> index 0ab83bb7bbdf..e3301e5fa037 100644
> --- a/fs/jfs/jfs_dtree.c
> +++ b/fs/jfs/jfs_dtree.c
> @@ -2903,7 +2903,7 @@ int jfs_readdir(struct file *file, struct dir_context *ctx)
> stbl = DT_GETSTBL(p);
>
> for (i = index; i < p->header.nextindex; i++) {
> - if (stbl[i] < 0 || stbl[i] >= DTPAGEMAXSLOT) {
> + if (stbl[i] < 0 || (unsigned char)stbl[i] >= DTPAGEMAXSLOT) {
> jfs_err("JFS: Invalid stbl[%d] = %d for inode %ld, block = %lld",
> i, stbl[i], (long)ip->i_ino, (long long)bn);
> free_page(dirent_buf);
> @@ -3108,7 +3108,7 @@ static int dtReadFirst(struct inode *ip, struct btstack * btstack)
> /* get the leftmost entry */
> stbl = DT_GETSTBL(p);
>
> - if (stbl[0] < 0 || stbl[0] >= DTPAGEMAXSLOT) {
> + if (stbl[0] < 0 || (unsigned char)stbl[0] >= DTPAGEMAXSLOT) {
> DT_PUTPAGE(mp);
> jfs_error(ip->i_sb, "stbl[0] out of bound\n");
> return -EIO;
On Mon, Feb 2, 2026, at 18:34, Dave Kleikamp wrote:
> On 2/2/26 3:49AM, Arnd Bergmann wrote:
>> From: Arnd Bergmann <arnd@arndb.de>
>>
>> A recent change for the range check started triggering a clang warning:
>>
>> fs/jfs/jfs_dtree.c:2906:31: error: result of comparison of constant 128 with expression of type 's8' (aka 'signed char') is always false [-Werror,-Wtautological-constant-out-of-range-compare]
>> 2906 | if (stbl[i] < 0 || stbl[i] >= DTPAGEMAXSLOT) {
>> | ~~~~~~~ ^ ~~~~~~~~~~~~~
>> fs/jfs/jfs_dtree.c:3111:30: error: result of comparison of constant 128 with expression of type 's8' (aka 'signed char') is always false [-Werror,-Wtautological-constant-out-of-range-compare]
>> 3111 | if (stbl[0] < 0 || stbl[0] >= DTPAGEMAXSLOT) {
>> | ~~~~~~~ ^ ~~~~~~~~~~~~~
>>
>> Both the old and the new check were useless, but the previous version
>> apparently did not lead to the warning.
>>
>> Rephrase this again by adding a cast. The check is still always false,
>> but the compiler shuts up about it.
>
> I think it would be better to just drop the useless part of these tests.
Fair enough, sent v2 now.
Arnd
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