[PATCH 5.15 147/168] btrfs: sysfs: convert scnprintf and snprintf to sysfs_emit

6 Jan 2025

5.15-stable review patch.  If anyone has any objections, please let me know.
------------------
From: Anand Jain anand.jain@oracle.com
[ Upstream commit 020e5277583dc26d7a5322ff2d334c764ac1faa8 ]
Commit 2efc459d06f1 ("sysfs: Add sysfs_emit and sysfs_emit_at to format
sysfs out") merged in 5.10 introduced two new functions sysfs_emit() and
sysfs_emit_at() which are aware of the PAGE_SIZE limit of the output
buffer.
Use the above two new functions instead of scnprintf() and snprintf()
in various sysfs show().
Reviewed-by: Josef Bacik josef@toxicpanda.com
Signed-off-by: Anand Jain anand.jain@oracle.com
Reviewed-by: David Sterba dsterba@suse.com
Signed-off-by: David Sterba dsterba@suse.com
Stable-dep-of: fca432e73db2 ("btrfs: sysfs: fix direct super block member reads")
Signed-off-by: Sasha Levin sashal@kernel.org
---
 fs/btrfs/sysfs.c | 93 +++++++++++++++++++++++-------------------------
 1 file changed, 44 insertions(+), 49 deletions(-)

diff --git a/fs/btrfs/sysfs.c b/fs/btrfs/sysfs.c
index 93a9dfbc8d13..bc8d5b4c279e 100644
--- a/fs/btrfs/sysfs.c
+++ b/fs/btrfs/sysfs.c
@@ -177,7 +177,7 @@ static ssize_t btrfs_feature_attr_show(struct kobject *kobj,
    } else
    	val = can_modify_feature(fa);
-	return scnprintf(buf, PAGE_SIZE, "%d\n", val);
+	return sysfs_emit(buf, "%d\n", val);
 }
static ssize_t btrfs_feature_attr_store(struct kobject *kobj,
@@ -333,7 +333,7 @@ static const struct attribute_group btrfs_feature_attr_group = {
 static ssize_t rmdir_subvol_show(struct kobject *kobj,
    			 struct kobj_attribute *ka, char *buf)
 {
-	return scnprintf(buf, PAGE_SIZE, "0\n");
+	return sysfs_emit(buf, "0\n");
 }
 BTRFS_ATTR(static_feature, rmdir_subvol, rmdir_subvol_show);
@@ -348,12 +348,12 @@ static ssize_t supported_checksums_show(struct kobject *kobj,
    	 * This "trick" only works as long as 'enum btrfs_csum_type' has
    	 * no holes in it
    	 */
-		ret += scnprintf(buf + ret, PAGE_SIZE - ret, "%s%s",
-				(i == 0 ? "" : " "), btrfs_super_csum_name(i));
+		ret += sysfs_emit_at(buf, ret, "%s%s", (i == 0 ? "" : " "),
+				     btrfs_super_csum_name(i));
}
-	ret += scnprintf(buf + ret, PAGE_SIZE - ret, "\n");
+	ret += sysfs_emit_at(buf, ret, "\n");
    return ret;
 }
 BTRFS_ATTR(static_feature, supported_checksums, supported_checksums_show);
@@ -361,7 +361,7 @@ BTRFS_ATTR(static_feature, supported_checksums, supported_checksums_show);
 static ssize_t send_stream_version_show(struct kobject *kobj,
    				struct kobj_attribute *ka, char *buf)
 {
-	return snprintf(buf, PAGE_SIZE, "%d\n", BTRFS_SEND_STREAM_VERSION);
+	return sysfs_emit(buf, "%d\n", BTRFS_SEND_STREAM_VERSION);
 }
 BTRFS_ATTR(static_feature, send_stream_version, send_stream_version_show);
@@ -381,9 +381,8 @@ static ssize_t supported_rescue_options_show(struct kobject *kobj,
    int i;
for (i = 0; i < ARRAY_SIZE(rescue_opts); i++)
-		ret += scnprintf(buf + ret, PAGE_SIZE - ret, "%s%s",
-				 (i ? " " : ""), rescue_opts[i]);
-	ret += scnprintf(buf + ret, PAGE_SIZE - ret, "\n");
+		ret += sysfs_emit_at(buf, ret, "%s%s", (i ? " " : ""), rescue_opts[i]);
+	ret += sysfs_emit_at(buf, ret, "\n");
    return ret;
 }
 BTRFS_ATTR(static_feature, supported_rescue_options,
@@ -397,10 +396,10 @@ static ssize_t supported_sectorsizes_show(struct kobject *kobj,
/* 4K sector size is also supported with 64K page size */
    if (PAGE_SIZE == SZ_64K)
-		ret += scnprintf(buf + ret, PAGE_SIZE - ret, "%u ", SZ_4K);
+		ret += sysfs_emit_at(buf, ret, "%u ", SZ_4K);
/* Only sectorsize == PAGE_SIZE is now supported */
-	ret += scnprintf(buf + ret, PAGE_SIZE - ret, "%lu\n", PAGE_SIZE);
+	ret += sysfs_emit_at(buf, ret, "%lu\n", PAGE_SIZE);
return ret;
 }
@@ -440,7 +439,7 @@ static ssize_t btrfs_discardable_bytes_show(struct kobject *kobj,
 {
    struct btrfs_fs_info *fs_info = discard_to_fs_info(kobj);
-	return scnprintf(buf, PAGE_SIZE, "%lld\n",
+	return sysfs_emit(buf, "%lld\n",
    		atomic64_read(&fs_info->discard_ctl.discardable_bytes));
 }
 BTRFS_ATTR(discard, discardable_bytes, btrfs_discardable_bytes_show);
@@ -451,7 +450,7 @@ static ssize_t btrfs_discardable_extents_show(struct kobject *kobj,
 {
    struct btrfs_fs_info *fs_info = discard_to_fs_info(kobj);
-	return scnprintf(buf, PAGE_SIZE, "%d\n",
+	return sysfs_emit(buf, "%d\n",
    		atomic_read(&fs_info->discard_ctl.discardable_extents));
 }
 BTRFS_ATTR(discard, discardable_extents, btrfs_discardable_extents_show);
@@ -462,8 +461,8 @@ static ssize_t btrfs_discard_bitmap_bytes_show(struct kobject *kobj,
 {
    struct btrfs_fs_info *fs_info = discard_to_fs_info(kobj);
-	return scnprintf(buf, PAGE_SIZE, "%llu\n",
-			fs_info->discard_ctl.discard_bitmap_bytes);
+	return sysfs_emit(buf, "%llu\n",
+			  fs_info->discard_ctl.discard_bitmap_bytes);
 }
 BTRFS_ATTR(discard, discard_bitmap_bytes, btrfs_discard_bitmap_bytes_show);
@@ -473,7 +472,7 @@ static ssize_t btrfs_discard_bytes_saved_show(struct kobject *kobj,
 {
    struct btrfs_fs_info *fs_info = discard_to_fs_info(kobj);
-	return scnprintf(buf, PAGE_SIZE, "%lld\n",
+	return sysfs_emit(buf, "%lld\n",
    	atomic64_read(&fs_info->discard_ctl.discard_bytes_saved));
 }
 BTRFS_ATTR(discard, discard_bytes_saved, btrfs_discard_bytes_saved_show);
@@ -484,8 +483,8 @@ static ssize_t btrfs_discard_extent_bytes_show(struct kobject *kobj,
 {
    struct btrfs_fs_info *fs_info = discard_to_fs_info(kobj);
-	return scnprintf(buf, PAGE_SIZE, "%llu\n",
-			fs_info->discard_ctl.discard_extent_bytes);
+	return sysfs_emit(buf, "%llu\n",
+			  fs_info->discard_ctl.discard_extent_bytes);
 }
 BTRFS_ATTR(discard, discard_extent_bytes, btrfs_discard_extent_bytes_show);
@@ -495,8 +494,8 @@ static ssize_t btrfs_discard_iops_limit_show(struct kobject *kobj,
 {
    struct btrfs_fs_info *fs_info = discard_to_fs_info(kobj);
-	return scnprintf(buf, PAGE_SIZE, "%u\n",
-			READ_ONCE(fs_info->discard_ctl.iops_limit));
+	return sysfs_emit(buf, "%u\n",
+			  READ_ONCE(fs_info->discard_ctl.iops_limit));
 }
static ssize_t btrfs_discard_iops_limit_store(struct kobject *kobj,
@@ -526,8 +525,8 @@ static ssize_t btrfs_discard_kbps_limit_show(struct kobject *kobj,
 {
    struct btrfs_fs_info *fs_info = discard_to_fs_info(kobj);
-	return scnprintf(buf, PAGE_SIZE, "%u\n",
-			READ_ONCE(fs_info->discard_ctl.kbps_limit));
+	return sysfs_emit(buf, "%u\n",
+			  READ_ONCE(fs_info->discard_ctl.kbps_limit));
 }
static ssize_t btrfs_discard_kbps_limit_store(struct kobject *kobj,
@@ -556,8 +555,8 @@ static ssize_t btrfs_discard_max_discard_size_show(struct kobject *kobj,
 {
    struct btrfs_fs_info *fs_info = discard_to_fs_info(kobj);
-	return scnprintf(buf, PAGE_SIZE, "%llu\n",
-			READ_ONCE(fs_info->discard_ctl.max_discard_size));
+	return sysfs_emit(buf, "%llu\n",
+			  READ_ONCE(fs_info->discard_ctl.max_discard_size));
 }
static ssize_t btrfs_discard_max_discard_size_store(struct kobject *kobj,
@@ -630,7 +629,7 @@ static ssize_t btrfs_show_u64(u64 *value_ptr, spinlock_t *lock, char *buf)
    val = *value_ptr;
    if (lock)
    	spin_unlock(lock);
-	return scnprintf(buf, PAGE_SIZE, "%llu\n", val);
+	return sysfs_emit(buf, "%llu\n", val);
 }
static ssize_t global_rsv_size_show(struct kobject *kobj,
@@ -676,7 +675,7 @@ static ssize_t raid_bytes_show(struct kobject *kobj,
    		val += block_group->used;
    }
    up_read(&sinfo->groups_sem);
-	return scnprintf(buf, PAGE_SIZE, "%llu\n", val);
+	return sysfs_emit(buf, "%llu\n", val);
 }
/*
@@ -774,7 +773,7 @@ static ssize_t btrfs_label_show(struct kobject *kobj,
    ssize_t ret;
spin_lock(&fs_info->super_lock);
-	ret = scnprintf(buf, PAGE_SIZE, label[0] ? "%s\n" : "%s", label);
+	ret = sysfs_emit(buf, label[0] ? "%s\n" : "%s", label);
    spin_unlock(&fs_info->super_lock);
return ret;
@@ -822,7 +821,7 @@ static ssize_t btrfs_nodesize_show(struct kobject *kobj,
 {
    struct btrfs_fs_info *fs_info = to_fs_info(kobj);
-	return scnprintf(buf, PAGE_SIZE, "%u\n", fs_info->super_copy->nodesize);
+	return sysfs_emit(buf, "%u\n", fs_info->super_copy->nodesize);
 }
BTRFS_ATTR(, nodesize, btrfs_nodesize_show);
@@ -832,8 +831,7 @@ static ssize_t btrfs_sectorsize_show(struct kobject *kobj,
 {
    struct btrfs_fs_info *fs_info = to_fs_info(kobj);
-	return scnprintf(buf, PAGE_SIZE, "%u\n",
-			 fs_info->super_copy->sectorsize);
+	return sysfs_emit(buf, "%u\n", fs_info->super_copy->sectorsize);
 }
BTRFS_ATTR(, sectorsize, btrfs_sectorsize_show);
@@ -843,7 +841,7 @@ static ssize_t btrfs_clone_alignment_show(struct kobject *kobj,
 {
    struct btrfs_fs_info *fs_info = to_fs_info(kobj);
-	return scnprintf(buf, PAGE_SIZE, "%u\n", fs_info->super_copy->sectorsize);
+	return sysfs_emit(buf, "%u\n", fs_info->super_copy->sectorsize);
 }
BTRFS_ATTR(, clone_alignment, btrfs_clone_alignment_show);
@@ -855,7 +853,7 @@ static ssize_t quota_override_show(struct kobject *kobj,
    int quota_override;
quota_override = test_bit(BTRFS_FS_QUOTA_OVERRIDE, &fs_info->flags);
-	return scnprintf(buf, PAGE_SIZE, "%d\n", quota_override);
+	return sysfs_emit(buf, "%d\n", quota_override);
 }
static ssize_t quota_override_store(struct kobject *kobj,
@@ -893,8 +891,7 @@ static ssize_t btrfs_metadata_uuid_show(struct kobject *kobj,
 {
    struct btrfs_fs_info *fs_info = to_fs_info(kobj);
-	return scnprintf(buf, PAGE_SIZE, "%pU\n",
-			fs_info->fs_devices->metadata_uuid);
+	return sysfs_emit(buf, "%pU\n", fs_info->fs_devices->metadata_uuid);
 }
BTRFS_ATTR(, metadata_uuid, btrfs_metadata_uuid_show);
@@ -905,9 +902,9 @@ static ssize_t btrfs_checksum_show(struct kobject *kobj,
    struct btrfs_fs_info *fs_info = to_fs_info(kobj);
    u16 csum_type = btrfs_super_csum_type(fs_info->super_copy);
-	return scnprintf(buf, PAGE_SIZE, "%s (%s)\n",
-			btrfs_super_csum_name(csum_type),
-			crypto_shash_driver_name(fs_info->csum_shash));
+	return sysfs_emit(buf, "%s (%s)\n",
+			  btrfs_super_csum_name(csum_type),
+			  crypto_shash_driver_name(fs_info->csum_shash));
 }
BTRFS_ATTR(, checksum, btrfs_checksum_show);
@@ -944,7 +941,7 @@ static ssize_t btrfs_exclusive_operation_show(struct kobject *kobj,
    		str = "UNKNOWN\n";
    		break;
    }
-	return scnprintf(buf, PAGE_SIZE, "%s", str);
+	return sysfs_emit(buf, "%s", str);
 }
 BTRFS_ATTR(, exclusive_operation, btrfs_exclusive_operation_show);
@@ -953,7 +950,7 @@ static ssize_t btrfs_generation_show(struct kobject *kobj,
 {
    struct btrfs_fs_info *fs_info = to_fs_info(kobj);
-	return scnprintf(buf, PAGE_SIZE, "%llu\n", fs_info->generation);
+	return sysfs_emit(buf, "%llu\n", fs_info->generation);
 }
 BTRFS_ATTR(, generation, btrfs_generation_show);
@@ -1031,8 +1028,7 @@ static ssize_t btrfs_bg_reclaim_threshold_show(struct kobject *kobj,
    struct btrfs_fs_info *fs_info = to_fs_info(kobj);
    ssize_t ret;
-	ret = scnprintf(buf, PAGE_SIZE, "%d\n",
-			READ_ONCE(fs_info->bg_reclaim_threshold));
+	ret = sysfs_emit(buf, "%d\n", READ_ONCE(fs_info->bg_reclaim_threshold));
return ret;
 }
@@ -1474,7 +1470,7 @@ static ssize_t btrfs_devinfo_in_fs_metadata_show(struct kobject *kobj,
val = !!test_bit(BTRFS_DEV_STATE_IN_FS_METADATA, &device->dev_state);
-	return scnprintf(buf, PAGE_SIZE, "%d\n", val);
+	return sysfs_emit(buf, "%d\n", val);
 }
 BTRFS_ATTR(devid, in_fs_metadata, btrfs_devinfo_in_fs_metadata_show);
@@ -1487,7 +1483,7 @@ static ssize_t btrfs_devinfo_missing_show(struct kobject *kobj,
val = !!test_bit(BTRFS_DEV_STATE_MISSING, &device->dev_state);
-	return scnprintf(buf, PAGE_SIZE, "%d\n", val);
+	return sysfs_emit(buf, "%d\n", val);
 }
 BTRFS_ATTR(devid, missing, btrfs_devinfo_missing_show);
@@ -1501,7 +1497,7 @@ static ssize_t btrfs_devinfo_replace_target_show(struct kobject *kobj,
val = !!test_bit(BTRFS_DEV_STATE_REPLACE_TGT, &device->dev_state);
-	return scnprintf(buf, PAGE_SIZE, "%d\n", val);
+	return sysfs_emit(buf, "%d\n", val);
 }
 BTRFS_ATTR(devid, replace_target, btrfs_devinfo_replace_target_show);
@@ -1512,8 +1508,7 @@ static ssize_t btrfs_devinfo_scrub_speed_max_show(struct kobject *kobj,
    struct btrfs_device *device = container_of(kobj, struct btrfs_device,
    					   devid_kobj);
-	return scnprintf(buf, PAGE_SIZE, "%llu\n",
-			 READ_ONCE(device->scrub_speed_max));
+	return sysfs_emit(buf, "%llu\n", READ_ONCE(device->scrub_speed_max));
 }
static ssize_t btrfs_devinfo_scrub_speed_max_store(struct kobject *kobj,
@@ -1545,7 +1540,7 @@ static ssize_t btrfs_devinfo_writeable_show(struct kobject *kobj,
val = !!test_bit(BTRFS_DEV_STATE_WRITEABLE, &device->dev_state);
-	return scnprintf(buf, PAGE_SIZE, "%d\n", val);
+	return sysfs_emit(buf, "%d\n", val);
 }
 BTRFS_ATTR(devid, writeable, btrfs_devinfo_writeable_show);
@@ -1556,14 +1551,14 @@ static ssize_t btrfs_devinfo_error_stats_show(struct kobject *kobj,
    					   devid_kobj);
if (!device->dev_stats_valid)
-		return scnprintf(buf, PAGE_SIZE, "invalid\n");
+		return sysfs_emit(buf, "invalid\n");
/*
     * Print all at once so we get a snapshot of all values from the same
     * time. Keep them in sync and in order of definition of
     * btrfs_dev_stat_values.
     */
-	return scnprintf(buf, PAGE_SIZE,
+	return sysfs_emit(buf,
    	"write_errs %d\n"
    	"read_errs %d\n"
    	"flush_errs %d\n"
-- 
2.39.5





    

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[PATCH 5.15 147/168] btrfs: sysfs: convert scnprintf and snprintf to sysfs_emit