[PATCH] fs/gfs2: use scnprintf() in show functions

[PATCH] fs/gfs2: use scnprintf() in show functions

[Pranav Tyagi]

Replace all snprintf() instances with scnprintf(). snprintf() returns
the number of bytes that would have been written had there been enough
space. For sysfs attributes, snprintf() should not be used with the
show() method. Instead use scnprintf() which returns the number of bytes
actually written.

Signed-off-by: Pranav Tyagi <pranav.tyagi03@gmail.com>
---
 fs/gfs2/sys.c | 16 ++++++++--------
 1 file changed, 8 insertions(+), 8 deletions(-)

diff --git a/fs/gfs2/sys.c b/fs/gfs2/sys.c
index c3c8842920d2..25c1d71359ed 100644
--- a/fs/gfs2/sys.c
+++ b/fs/gfs2/sys.c
@@ -59,7 +59,7 @@ static struct kset *gfs2_kset;
 
 static ssize_t id_show(struct gfs2_sbd *sdp, char *buf)
 {
-	return snprintf(buf, PAGE_SIZE, "%u:%u\n",
+	return scnprintf(buf, PAGE_SIZE, "%u:%u\n",
 			MAJOR(sdp->sd_vfs->s_dev), MINOR(sdp->sd_vfs->s_dev));
 }
 
@@ -68,7 +68,7 @@ static ssize_t status_show(struct gfs2_sbd *sdp, char *buf)
 	unsigned long f = sdp->sd_flags;
 	ssize_t s;
 
-	s = snprintf(buf, PAGE_SIZE,
+	s = scnprintf(buf, PAGE_SIZE,
 		     "Journal Checked:          %d\n"
 		     "Journal Live:             %d\n"
 		     "Journal ID:               %d\n"
@@ -140,7 +140,7 @@ static ssize_t status_show(struct gfs2_sbd *sdp, char *buf)
 
 static ssize_t fsname_show(struct gfs2_sbd *sdp, char *buf)
 {
-	return snprintf(buf, PAGE_SIZE, "%s\n", sdp->sd_fsname);
+	return scnprintf(buf, PAGE_SIZE, "%s\n", sdp->sd_fsname);
 }
 
 static ssize_t uuid_show(struct gfs2_sbd *sdp, char *buf)
@@ -150,7 +150,7 @@ static ssize_t uuid_show(struct gfs2_sbd *sdp, char *buf)
 	buf[0] = '\0';
 	if (uuid_is_null(&s->s_uuid))
 		return 0;
-	return snprintf(buf, PAGE_SIZE, "%pUB\n", &s->s_uuid);
+	return scnprintf(buf, PAGE_SIZE, "%pUB\n", &s->s_uuid);
 }
 
 static ssize_t freeze_show(struct gfs2_sbd *sdp, char *buf)
@@ -158,7 +158,7 @@ static ssize_t freeze_show(struct gfs2_sbd *sdp, char *buf)
 	struct super_block *sb = sdp->sd_vfs;
 	int frozen = (sb->s_writers.frozen == SB_UNFROZEN) ? 0 : 1;
 
-	return snprintf(buf, PAGE_SIZE, "%d\n", frozen);
+	return scnprintf(buf, PAGE_SIZE, "%d\n", frozen);
 }
 
 static ssize_t freeze_store(struct gfs2_sbd *sdp, const char *buf, size_t len)
@@ -194,7 +194,7 @@ static ssize_t freeze_store(struct gfs2_sbd *sdp, const char *buf, size_t len)
 static ssize_t withdraw_show(struct gfs2_sbd *sdp, char *buf)
 {
 	unsigned int b = gfs2_withdrawing_or_withdrawn(sdp);
-	return snprintf(buf, PAGE_SIZE, "%u\n", b);
+	return scnprintf(buf, PAGE_SIZE, "%u\n", b);
 }
 
 static ssize_t withdraw_store(struct gfs2_sbd *sdp, const char *buf, size_t len)
@@ -626,7 +626,7 @@ static struct attribute *lock_module_attrs[] = {
 
 static ssize_t quota_scale_show(struct gfs2_sbd *sdp, char *buf)
 {
-	return snprintf(buf, PAGE_SIZE, "%u %u\n",
+	return scnprintf(buf, PAGE_SIZE, "%u %u\n",
 			sdp->sd_tune.gt_quota_scale_num,
 			sdp->sd_tune.gt_quota_scale_den);
 }
@@ -679,7 +679,7 @@ static struct gfs2_attr tune_attr_##name = __ATTR(name, 0644, show, store)
 #define TUNE_ATTR_2(name, store)                                              \
 static ssize_t name##_show(struct gfs2_sbd *sdp, char *buf)                   \
 {                                                                             \
-	return snprintf(buf, PAGE_SIZE, "%u\n", sdp->sd_tune.gt_##name);      \
+	return scnprintf(buf, PAGE_SIZE, "%u\n", sdp->sd_tune.gt_##name);     \
 }                                                                             \
 TUNE_ATTR_3(name, name##_show, store)
 
-- 
2.49.0

Re: [PATCH] fs/gfs2: use scnprintf() in show functions

[Greg KH]

On Mon, Jun 16, 2025 at 04:26:26PM +0530, Pranav Tyagi wrote:
> Replace all snprintf() instances with scnprintf(). snprintf() returns
> the number of bytes that would have been written had there been enough
> space. For sysfs attributes, snprintf() should not be used with the
> show() method. Instead use scnprintf() which returns the number of bytes
> actually written.
> 
> Signed-off-by: Pranav Tyagi <pranav.tyagi03@gmail.com>
> ---
>  fs/gfs2/sys.c | 16 ++++++++--------
>  1 file changed, 8 insertions(+), 8 deletions(-)

sysfs_emit() or no change at all please.