block: partitions: Replace pp_buf with struct seq_buf

In preparation for removing the strlcat API[1], replace the char *pp_buf with a struct seq_buf, which tracks the current write position and remaining space internally. This allows for:

- Direct use of seq_buf_printf() in place of snprintf()+strlcat() pairs, eliminating local tmp buffers throughout.
- Adjacent strlcat() calls that build strings piece-by-piece (e.g., strlcat("["); strlcat(name); strlcat("]")) to be collapsed into single seq_buf_printf() calls.
- Simpler call sites: seq_buf_puts() takes only the buffer and string, with no need to pass PAGE_SIZE at every call.

The backing buffer allocation is unchanged (__get_free_page), and the output path uses seq_buf_str() to NUL-terminate before passing to printk().

Link https://github.com/KSPP/linux/issues/370 [1]

Cc Andy Shevchenko <[email protected]>

Cc Josh Law <[email protected]>

Signed-off-by Kees Cook <[email protected]>

---
I couldn't help myself. Here's the full patch, as I suggested in
https://lore.kernel.org/lkml/202603201230.74BBFFABAD@keescook/
There are plenty more like this to do...
---

block/partitions/check.h   |  8 ++---
block/partitions/core.c    | 20 ++++++------
block/partitions/acorn.c   | 32 ++++++++----------
block/partitions/aix.c     | 21 +++++-------
block/partitions/amiga.c   | 35 +++++++++-----------
block/partitions/atari.c   | 12 +++----
block/partitions/cmdline.c |  6 ++--
block/partitions/efi.c     |  2 +-
block/partitions/ibm.c     | 27 ++++++---------
block/partitions/karma.c   |  2 +-
block/partitions/ldm.c     |  4 +--
block/partitions/mac.c     |  4 +--
block/partitions/msdos.c   | 67 +++++++++++++-------------------------
block/partitions/of.c      |  6 ++--
block/partitions/osf.c     |  2 +-
block/partitions/sgi.c     |  2 +-
block/partitions/sun.c     |  2 +-
block/partitions/sysv68.c  |  9 ++---
block/partitions/ultrix.c  |  2 +-
19 files changed, 106 insertions(+), 157 deletions(-)

block/partitions/check.h +3 -5

index e5c1c61eb353..b0997467b61a 100644
@@ -1,6 +1,7 @@
 /* SPDX-License-Identifier: GPL-2.0 */
 #include <linux/pagemap.h>
 #include <linux/blkdev.h>
+#include <linux/seq_buf.h>
 #include "../blk.h"
 
 /*

@@ -20,7 +21,7 @@ struct parsed_partitions {
 	int next;
 	int limit;
 	bool access_beyond_eod;
-	char *pp_buf;
+	struct seq_buf pp_buf;
 };
 
 typedef struct {

@@ -37,12 +38,9 @@ static inline void
 put_partition(struct parsed_partitions *p, int n, sector_t from, sector_t size)
 {
 	if (n < p->limit) {
-		char tmp[1 + BDEVNAME_SIZE + 10 + 1];
-
 		p->parts[n].from = from;
 		p->parts[n].size = size;
-		snprintf(tmp, sizeof(tmp), " %s%d", p->name, n);
-		strlcat(p->pp_buf, tmp, PAGE_SIZE);
+		seq_buf_printf(&p->pp_buf, " %s%d", p->name, n);
 	}
 }
 

block/partitions/core.c +10 -10

index 740228750aaf..3b5928836c69 100644
@@ -123,16 +123,16 @@ static struct parsed_partitions *check_partition(struct gendisk *hd)
 	state = allocate_partitions(hd);
 	if (!state)
 		return NULL;
-	state->pp_buf = (char *)__get_free_page(GFP_KERNEL);
-	if (!state->pp_buf) {
+	state->pp_buf.buffer = (char *)__get_free_page(GFP_KERNEL);
+	if (!state->pp_buf.buffer) {
 		free_partitions(state);
 		return NULL;
 	}
-	state->pp_buf[0] = '\0';
+	seq_buf_init(&state->pp_buf, state->pp_buf.buffer, PAGE_SIZE);
 
 	state->disk = hd;
 	strscpy(state->name, hd->disk_name);
-	snprintf(state->pp_buf, PAGE_SIZE, " %s:", state->name);
+	seq_buf_printf(&state->pp_buf, " %s:", state->name);
 	if (isdigit(state->name[strlen(state->name)-1]))
 		sprintf(state->name, "p");
 

@@ -151,9 +151,9 @@ static struct parsed_partitions *check_partition(struct gendisk *hd)
 
 	}
 	if (res > 0) {
-		printk(KERN_INFO "%s", state->pp_buf);
+		printk(KERN_INFO "%s", seq_buf_str(&state->pp_buf));
 
-		free_page((unsigned long)state->pp_buf);
+		free_page((unsigned long)state->pp_buf.buffer);
 		return state;
 	}
 	if (state->access_beyond_eod)

@@ -164,12 +164,12 @@ static struct parsed_partitions *check_partition(struct gendisk *hd)
 	if (err)
 		res = err;
 	if (res) {
-		strlcat(state->pp_buf,
-			" unable to read partition table\n", PAGE_SIZE);
-		printk(KERN_INFO "%s", state->pp_buf);
+		seq_buf_puts(&state->pp_buf,
+			     " unable to read partition table\n");
+		printk(KERN_INFO "%s", seq_buf_str(&state->pp_buf));
 	}
 
-	free_page((unsigned long)state->pp_buf);
+	free_page((unsigned long)state->pp_buf.buffer);
 	free_partitions(state);
 	return ERR_PTR(res);
 }

block/partitions/acorn.c +14 -18

index d2fc122d7426..9f7389f174d0 100644
@@ -40,9 +40,7 @@ adfs_partition(struct parsed_partitions *state, char *name, char *data,
 		   (le32_to_cpu(dr->disc_size) >> 9);
 
 	if (name) {
-		strlcat(state->pp_buf, " [", PAGE_SIZE);
-		strlcat(state->pp_buf, name, PAGE_SIZE);
-		strlcat(state->pp_buf, "]", PAGE_SIZE);
+		seq_buf_printf(&state->pp_buf, " [%s]", name);
 	}
 	put_partition(state, slot, first_sector, nr_sects);
 	return dr;

@@ -78,14 +76,14 @@ static int riscix_partition(struct parsed_partitions *state,
 	if (!rr)
 		return -1;
 
-	strlcat(state->pp_buf, " [RISCiX]", PAGE_SIZE);
+	seq_buf_puts(&state->pp_buf, " [RISCiX]");
 
 
 	if (rr->magic == RISCIX_MAGIC) {
 		unsigned long size = nr_sects > 2 ? 2 : nr_sects;
 		int part;
 
-		strlcat(state->pp_buf, " <", PAGE_SIZE);
+		seq_buf_puts(&state->pp_buf, " <");
 
 		put_partition(state, slot++, first_sect, size);
 		for (part = 0; part < 8; part++) {

@@ -94,13 +92,11 @@ static int riscix_partition(struct parsed_partitions *state,
 				put_partition(state, slot++,
 					le32_to_cpu(rr->part[part].start),
 					le32_to_cpu(rr->part[part].length));
-				strlcat(state->pp_buf, "(", PAGE_SIZE);
-				strlcat(state->pp_buf, rr->part[part].name, PAGE_SIZE);
-				strlcat(state->pp_buf, ")", PAGE_SIZE);
+				seq_buf_printf(&state->pp_buf, "(%s)", rr->part[part].name);
 			}
 		}
 
-		strlcat(state->pp_buf, " >\n", PAGE_SIZE);
+		seq_buf_puts(&state->pp_buf, " >\n");
 	} else {
 		put_partition(state, slot++, first_sect, nr_sects);
 	}

@@ -130,7 +126,7 @@ static int linux_partition(struct parsed_partitions *state,
 	struct linux_part *linuxp;
 	unsigned long size = nr_sects > 2 ? 2 : nr_sects;
 
-	strlcat(state->pp_buf, " [Linux]", PAGE_SIZE);
+	seq_buf_puts(&state->pp_buf, " [Linux]");
 
 	put_partition(state, slot++, first_sect, size);
 

@@ -138,7 +134,7 @@ static int linux_partition(struct parsed_partitions *state,
 	if (!linuxp)
 		return -1;
 
-	strlcat(state->pp_buf, " <", PAGE_SIZE);
+	seq_buf_puts(&state->pp_buf, " <");
 	while (linuxp->magic == cpu_to_le32(LINUX_NATIVE_MAGIC) ||
 	       linuxp->magic == cpu_to_le32(LINUX_SWAP_MAGIC)) {
 		if (slot == state->limit)

@@ -148,7 +144,7 @@ static int linux_partition(struct parsed_partitions *state,
 				 le32_to_cpu(linuxp->nr_sects));
 		linuxp ++;
 	}
-	strlcat(state->pp_buf, " >", PAGE_SIZE);
+	seq_buf_puts(&state->pp_buf, " >");
 
 	put_dev_sector(sect);
 	return slot;

@@ -293,7 +289,7 @@ int adfspart_check_ADFS(struct parsed_partitions *state)
 			break;
 		}
 	}
-	strlcat(state->pp_buf, "\n", PAGE_SIZE);
+	seq_buf_puts(&state->pp_buf, "\n");
 	return 1;
 }
 #endif

@@ -366,7 +362,7 @@ int adfspart_check_ICS(struct parsed_partitions *state)
 		return 0;
 	}
 
-	strlcat(state->pp_buf, " [ICS]", PAGE_SIZE);
+	seq_buf_puts(&state->pp_buf, " [ICS]");
 
 	for (slot = 1, p = (const struct ics_part *)data; p->size; p++) {
 		u32 start = le32_to_cpu(p->start);

@@ -400,7 +396,7 @@ int adfspart_check_ICS(struct parsed_partitions *state)
 	}
 
 	put_dev_sector(sect);
-	strlcat(state->pp_buf, "\n", PAGE_SIZE);
+	seq_buf_puts(&state->pp_buf, "\n");
 	return 1;
 }
 #endif

@@ -460,7 +456,7 @@ int adfspart_check_POWERTEC(struct parsed_partitions *state)
 		return 0;
 	}
 
-	strlcat(state->pp_buf, " [POWERTEC]", PAGE_SIZE);
+	seq_buf_puts(&state->pp_buf, " [POWERTEC]");
 
 	for (i = 0, p = (const struct ptec_part *)data; i < 12; i++, p++) {
 		u32 start = le32_to_cpu(p->start);

@@ -471,7 +467,7 @@ int adfspart_check_POWERTEC(struct parsed_partitions *state)
 	}
 
 	put_dev_sector(sect);
-	strlcat(state->pp_buf, "\n", PAGE_SIZE);
+	seq_buf_puts(&state->pp_buf, "\n");
 	return 1;
 }
 #endif

@@ -542,7 +538,7 @@ int adfspart_check_EESOX(struct parsed_partitions *state)
 
 		size = get_capacity(state->disk);
 		put_partition(state, slot++, start, size - start);
-		strlcat(state->pp_buf, "\n", PAGE_SIZE);
+		seq_buf_puts(&state->pp_buf, "\n");
 	}
 
 	return i ? 1 : 0;

block/partitions/aix.c +8 -13

index a886cefbefbb..29b8f4cebb63 100644
@@ -173,24 +173,22 @@ int aix_partition(struct parsed_partitions *state)
 	if (d) {
 		struct lvm_rec *p = (struct lvm_rec *)d;
 		u16 lvm_version = be16_to_cpu(p->version);
-		char tmp[64];
 
 		if (lvm_version == 1) {
 			int pp_size_log2 = be16_to_cpu(p->pp_size);
 
 			pp_bytes_size = 1 << pp_size_log2;
 			pp_blocks_size = pp_bytes_size / 512;
-			snprintf(tmp, sizeof(tmp),
-				" AIX LVM header version %u found\n",
-				lvm_version);
+			seq_buf_printf(&state->pp_buf,
+				       " AIX LVM header version %u found\n",
+				       lvm_version);
 			vgda_len = be32_to_cpu(p->vgda_len);
 			vgda_sector = be32_to_cpu(p->vgda_psn[0]);
 		} else {
-			snprintf(tmp, sizeof(tmp),
-				" unsupported AIX LVM version %d found\n",
-				lvm_version);
+			seq_buf_printf(&state->pp_buf,
+				       " unsupported AIX LVM version %d found\n",
+				       lvm_version);
 		}
-		strlcat(state->pp_buf, tmp, PAGE_SIZE);
 		put_dev_sector(sect);
 	}
 	if (vgda_sector && (d = read_part_sector(state, vgda_sector, &sect))) {

@@ -251,14 +249,11 @@ int aix_partition(struct parsed_partitions *state)
 				continue;
 			}
 			if (lp_ix == lvip[lv_ix].pps_per_lv) {
-				char tmp[70];
-
 				put_partition(state, lv_ix + 1,
 				  (i + 1 - lp_ix) * pp_blocks_size + psn_part1,
 				  lvip[lv_ix].pps_per_lv * pp_blocks_size);
-				snprintf(tmp, sizeof(tmp), " <%s>\n",
-					 n[lv_ix].name);
-				strlcat(state->pp_buf, tmp, PAGE_SIZE);
+				seq_buf_printf(&state->pp_buf, " <%s>\n",
+					       n[lv_ix].name);
 				lvip[lv_ix].lv_is_contiguous = 1;
 				ret = 1;
 				next_lp_ix = 1;

block/partitions/amiga.c +15 -20

index 506921095412..8325046a14eb 100644
@@ -81,13 +81,8 @@ int amiga_partition(struct parsed_partitions *state)
 	/* blksize is blocks per 512 byte standard block */
 	blksize = be32_to_cpu( rdb->rdb_BlockBytes ) / 512;
 
-	{
-		char tmp[7 + 10 + 1 + 1];
-
-		/* Be more informative */
-		snprintf(tmp, sizeof(tmp), " RDSK (%d)", blksize * 512);
-		strlcat(state->pp_buf, tmp, PAGE_SIZE);
-	}
+	/* Be more informative */
+	seq_buf_printf(&state->pp_buf, " RDSK (%d)", blksize * 512);
 	blk = be32_to_cpu(rdb->rdb_PartitionList);
 	put_dev_sector(sect);
 	for (part = 1; (s32) blk>0 && part<=16; part++, put_dev_sector(sect)) {

@@ -179,27 +174,27 @@ int amiga_partition(struct parsed_partitions *state)
 		{
 			/* Be even more informative to aid mounting */
 			char dostype[4];
-			char tmp[42];
 
 			__be32 *dt = (__be32 *)dostype;
 			*dt = pb->pb_Environment[16];
 			if (dostype[3] < ' ')
-				snprintf(tmp, sizeof(tmp), " (%c%c%c^%c)",
-					dostype[0], dostype[1],
-					dostype[2], dostype[3] + '@' );
+				seq_buf_printf(&state->pp_buf,
+					       " (%c%c%c^%c)",
+					       dostype[0], dostype[1],
+					       dostype[2],
+					       dostype[3] + '@');
 			else
-				snprintf(tmp, sizeof(tmp), " (%c%c%c%c)",
-					dostype[0], dostype[1],
-					dostype[2], dostype[3]);
-			strlcat(state->pp_buf, tmp, PAGE_SIZE);
-			snprintf(tmp, sizeof(tmp), "(res %d spb %d)",
-				be32_to_cpu(pb->pb_Environment[6]),
-				be32_to_cpu(pb->pb_Environment[4]));
-			strlcat(state->pp_buf, tmp, PAGE_SIZE);
+				seq_buf_printf(&state->pp_buf,
+					       " (%c%c%c%c)",
+					       dostype[0], dostype[1],
+					       dostype[2], dostype[3]);
+			seq_buf_printf(&state->pp_buf, "(res %d spb %d)",
+				       be32_to_cpu(pb->pb_Environment[6]),
+				       be32_to_cpu(pb->pb_Environment[4]));
 		}
 		res = 1;
 	}
-	strlcat(state->pp_buf, "\n", PAGE_SIZE);
+	seq_buf_puts(&state->pp_buf, "\n");
 

rdb_done:

	return res;

block/partitions/atari.c +6 -6

index 9655c728262a..2438d1448f38 100644
@@ -70,7 +70,7 @@ int atari_partition(struct parsed_partitions *state)
 	}
 
 	pi = &rs->part[0];
-	strlcat(state->pp_buf, " AHDI", PAGE_SIZE);
+	seq_buf_puts(&state->pp_buf, " AHDI");
 	for (slot = 1; pi < &rs->part[4] && slot < state->limit; slot++, pi++) {
 		struct rootsector *xrs;
 		Sector sect2;

@@ -89,7 +89,7 @@ int atari_partition(struct parsed_partitions *state)
 #ifdef ICD_PARTS
 		part_fmt = 1;
 #endif
-		strlcat(state->pp_buf, " XGM<", PAGE_SIZE);
+		seq_buf_puts(&state->pp_buf, " XGM<");
 		partsect = extensect = be32_to_cpu(pi->st);
 		while (1) {
 			xrs = read_part_sector(state, partsect, &sect2);

@@ -128,14 +128,14 @@ int atari_partition(struct parsed_partitions *state)
 				break;
 			}
 		}
-		strlcat(state->pp_buf, " >", PAGE_SIZE);
+		seq_buf_puts(&state->pp_buf, " >");
 	}
 #ifdef ICD_PARTS
 	if ( part_fmt!=1 ) { /* no extended partitions -> test ICD-format */
 		pi = &rs->icdpart[0];
 		/* sanity check: no ICD format if first partition invalid */
 		if (OK_id(pi->id)) {
-			strlcat(state->pp_buf, " ICD<", PAGE_SIZE);
+			seq_buf_puts(&state->pp_buf, " ICD<");
 			for (; pi < &rs->icdpart[8] && slot < state->limit; slot++, pi++) {
 				/* accept only GEM,BGM,RAW,LNX,SWP partitions */
 				if (!((pi->flg & 1) && OK_id(pi->id)))

@@ -144,13 +144,13 @@ int atari_partition(struct parsed_partitions *state)
 						be32_to_cpu(pi->st),
 						be32_to_cpu(pi->siz));
 			}
-			strlcat(state->pp_buf, " >", PAGE_SIZE);
+			seq_buf_puts(&state->pp_buf, " >");
 		}
 	}
 #endif
 	put_dev_sector(sect);
 
-	strlcat(state->pp_buf, "\n", PAGE_SIZE);
+	seq_buf_puts(&state->pp_buf, "\n");
 
 	return 1;
 }

block/partitions/cmdline.c +2 -4

index a2b1870c3fd4..4fd52ed154b4 100644
@@ -229,7 +229,6 @@ static int add_part(int slot, struct cmdline_subpart *subpart,
 		struct parsed_partitions *state)
 {
 	struct partition_meta_info *info;
-	char tmp[sizeof(info->volname) + 4];
 
 	if (slot >= state->limit)
 		return 1;

@@ -244,8 +243,7 @@ static int add_part(int slot, struct cmdline_subpart *subpart,
 
 	strscpy(info->volname, subpart->name, sizeof(info->volname));
 
-	snprintf(tmp, sizeof(tmp), "(%s)", info->volname);
-	strlcat(state->pp_buf, tmp, PAGE_SIZE);
+	seq_buf_printf(&state->pp_buf, "(%s)", info->volname);
 
 	state->parts[slot].has_info = true;
 

@@ -379,7 +377,7 @@ int cmdline_partition(struct parsed_partitions *state)
 	cmdline_parts_set(parts, disk_size, state);
 	cmdline_parts_verifier(1, state);
 
-	strlcat(state->pp_buf, "\n", PAGE_SIZE);
+	seq_buf_puts(&state->pp_buf, "\n");
 
 	return 1;
 }

block/partitions/efi.c +1 -1

index 75474fb3848e..9865d59093fa 100644
@@ -751,6 +751,6 @@ int efi_partition(struct parsed_partitions *state)
 	}
 	kfree(ptes);
 	kfree(gpt);
-	strlcat(state->pp_buf, "\n", PAGE_SIZE);
+	seq_buf_puts(&state->pp_buf, "\n");
 	return 1;
 }

block/partitions/ibm.c +10 -17

index 9311ad5fb95d..54047e722a9d 100644
@@ -173,15 +173,13 @@ static int find_vol1_partitions(struct parsed_partitions *state,
 {
 	sector_t blk;
 	int counter;
-	char tmp[64];
 	Sector sect;
 	unsigned char *data;
 	loff_t offset, size;
 	struct vtoc_format1_label f1;
 	int secperblk;
 
-	snprintf(tmp, sizeof(tmp), "VOL1/%8s:", name);
-	strlcat(state->pp_buf, tmp, PAGE_SIZE);
+	seq_buf_printf(&state->pp_buf, "VOL1/%8s:", name);
 	/*
 	 * get start of VTOC from the disk label and then search for format1
 	 * and format8 labels

@@ -219,7 +217,7 @@ static int find_vol1_partitions(struct parsed_partitions *state,
 		blk++;
 		data = read_part_sector(state, blk * secperblk, &sect);
 	}
-	strlcat(state->pp_buf, "\n", PAGE_SIZE);
+	seq_buf_puts(&state->pp_buf, "\n");
 
 	if (!data)
 		return -1;

@@ -237,11 +235,9 @@ static int find_lnx1_partitions(struct parsed_partitions *state,
 				dasd_information2_t *info)
 {
 	loff_t offset, geo_size, size;
-	char tmp[64];
 	int secperblk;
 
-	snprintf(tmp, sizeof(tmp), "LNX1/%8s:", name);
-	strlcat(state->pp_buf, tmp, PAGE_SIZE);
+	seq_buf_printf(&state->pp_buf, "LNX1/%8s:", name);
 	secperblk = blocksize >> 9;
 	if (label->lnx.ldl_version == 0xf2) {
 		size = label->lnx.formatted_blocks * secperblk;

@@ -258,7 +254,7 @@ static int find_lnx1_partitions(struct parsed_partitions *state,
 		size = nr_sectors;
 		if (size != geo_size) {
 			if (!info) {
-				strlcat(state->pp_buf, "\n", PAGE_SIZE);
+				seq_buf_puts(&state->pp_buf, "\n");
 				return 1;
 			}
 			if (!strcmp(info->type, "ECKD"))

@@ -270,7 +266,7 @@ static int find_lnx1_partitions(struct parsed_partitions *state,
 	/* first and only partition starts in the first block after the label */
 	offset = labelsect + secperblk;
 	put_partition(state, 1, offset, size - offset);
-	strlcat(state->pp_buf, "\n", PAGE_SIZE);
+	seq_buf_puts(&state->pp_buf, "\n");
 	return 1;
 }
 

@@ -282,7 +278,6 @@ static int find_cms1_partitions(struct parsed_partitions *state,
 				sector_t labelsect)
 {
 	loff_t offset, size;
-	char tmp[64];
 	int secperblk;
 
 	/*

@@ -291,14 +286,12 @@ static int find_cms1_partitions(struct parsed_partitions *state,
 	blocksize = label->cms.block_size;
 	secperblk = blocksize >> 9;
 	if (label->cms.disk_offset != 0) {
-		snprintf(tmp, sizeof(tmp), "CMS1/%8s(MDSK):", name);
-		strlcat(state->pp_buf, tmp, PAGE_SIZE);
+		seq_buf_printf(&state->pp_buf, "CMS1/%8s(MDSK):", name);
 		/* disk is reserved minidisk */
 		offset = label->cms.disk_offset * secperblk;
 		size = (label->cms.block_count - 1) * secperblk;
 	} else {
-		snprintf(tmp, sizeof(tmp), "CMS1/%8s:", name);
-		strlcat(state->pp_buf, tmp, PAGE_SIZE);
+		seq_buf_printf(&state->pp_buf, "CMS1/%8s:", name);
 		/*
 		 * Special case for FBA devices:
 		 * If an FBA device is CMS formatted with blocksize > 512 byte

@@ -314,7 +307,7 @@ static int find_cms1_partitions(struct parsed_partitions *state,
 	}
 
 	put_partition(state, 1, offset, size-offset);
-	strlcat(state->pp_buf, "\n", PAGE_SIZE);
+	seq_buf_puts(&state->pp_buf, "\n");
 	return 1;
 }
 

@@ -391,11 +384,11 @@ int ibm_partition(struct parsed_partitions *state)
 		 */
 		res = 1;
 		if (info->format == DASD_FORMAT_LDL) {
-			strlcat(state->pp_buf, "(nonl)", PAGE_SIZE);
+			seq_buf_puts(&state->pp_buf, "(nonl)");
 			size = nr_sectors;
 			offset = (info->label_block + 1) * (blocksize >> 9);
 			put_partition(state, 1, offset, size-offset);
-			strlcat(state->pp_buf, "\n", PAGE_SIZE);
+			seq_buf_puts(&state->pp_buf, "\n");
 		}
 	} else
 		res = 0;

block/partitions/karma.c +1 -1

index 4d93512f4bd4..a4e3c5050177 100644
@@ -53,7 +53,7 @@ int karma_partition(struct parsed_partitions *state)
 		}
 		slot++;
 	}
-	strlcat(state->pp_buf, "\n", PAGE_SIZE);
+	seq_buf_puts(&state->pp_buf, "\n");
 	put_dev_sector(sect);
 	return 1;
 }

block/partitions/ldm.c +2 -2

index 776b4ad95091..c0bdcae58a3e 100644
@@ -582,7 +582,7 @@ static bool ldm_create_data_partitions (struct parsed_partitions *pp,
 		return false;
 	}
 
-	strlcat(pp->pp_buf, " [LDM]", PAGE_SIZE);
+	seq_buf_puts(&pp->pp_buf, " [LDM]");
 
 	/* Create the data partitions */
 	list_for_each (item, &ldb->v_part) {

@@ -597,7 +597,7 @@ static bool ldm_create_data_partitions (struct parsed_partitions *pp,
 		part_num++;
 	}
 
-	strlcat(pp->pp_buf, "\n", PAGE_SIZE);
+	seq_buf_puts(&pp->pp_buf, "\n");
 	return true;
 }
 

block/partitions/mac.c +2 -2

index b02530d98629..df03ca428e15 100644
@@ -86,7 +86,7 @@ int mac_partition(struct parsed_partitions *state)
 	if (blocks_in_map >= state->limit)
 		blocks_in_map = state->limit - 1;
 
-	strlcat(state->pp_buf, " [mac]", PAGE_SIZE);
+	seq_buf_puts(&state->pp_buf, " [mac]");
 	for (slot = 1; slot <= blocks_in_map; ++slot) {
 		int pos = slot * secsize;
 		put_dev_sector(sect);

@@ -152,6 +152,6 @@ int mac_partition(struct parsed_partitions *state)
 #endif
 
 	put_dev_sector(sect);
-	strlcat(state->pp_buf, "\n", PAGE_SIZE);
+	seq_buf_puts(&state->pp_buf, "\n");
 	return 1;
 }

block/partitions/msdos.c +23 -44

index 073be78ba0b0..200ea53ea6a2 100644
@@ -263,18 +263,11 @@ static void parse_solaris_x86(struct parsed_partitions *state,
 		put_dev_sector(sect);
 		return;
 	}
-	{
-		char tmp[1 + BDEVNAME_SIZE + 10 + 11 + 1];
-
-		snprintf(tmp, sizeof(tmp), " %s%d: <solaris:", state->name, origin);
-		strlcat(state->pp_buf, tmp, PAGE_SIZE);
-	}
+	seq_buf_printf(&state->pp_buf, " %s%d: <solaris:", state->name, origin);
 	if (le32_to_cpu(v->v_version) != 1) {
-		char tmp[64];
-
-		snprintf(tmp, sizeof(tmp), "  cannot handle version %d vtoc>\n",
-			 le32_to_cpu(v->v_version));
-		strlcat(state->pp_buf, tmp, PAGE_SIZE);
+		seq_buf_printf(&state->pp_buf,
+			       "  cannot handle version %d vtoc>\n",
+			       le32_to_cpu(v->v_version));
 		put_dev_sector(sect);
 		return;
 	}

@@ -282,12 +275,10 @@ static void parse_solaris_x86(struct parsed_partitions *state,
 	max_nparts = le16_to_cpu(v->v_nparts) > 8 ? SOLARIS_X86_NUMSLICE : 8;
 	for (i = 0; i < max_nparts && state->next < state->limit; i++) {
 		struct solaris_x86_slice *s = &v->v_slice[i];
-		char tmp[3 + 10 + 1 + 1];
 
 		if (s->s_size == 0)
 			continue;
-		snprintf(tmp, sizeof(tmp), " [s%d]", i);
-		strlcat(state->pp_buf, tmp, PAGE_SIZE);
+		seq_buf_printf(&state->pp_buf, " [s%d]", i);
 		/* solaris partitions are relative to current MS-DOS
 		 * one; must add the offset of the current partition */
 		put_partition(state, state->next++,

@@ -295,7 +286,7 @@ static void parse_solaris_x86(struct parsed_partitions *state,
 				 le32_to_cpu(s->s_size));
 	}
 	put_dev_sector(sect);
-	strlcat(state->pp_buf, " >\n", PAGE_SIZE);
+	seq_buf_puts(&state->pp_buf, " >\n");
 #endif
 }
 

@@ -359,7 +350,6 @@ static void parse_bsd(struct parsed_partitions *state,
 	Sector sect;
 	struct bsd_disklabel *l;
 	struct bsd_partition *p;
-	char tmp[64];
 
 	l = read_part_sector(state, offset + 1, &sect);
 	if (!l)

@@ -369,8 +359,7 @@ static void parse_bsd(struct parsed_partitions *state,
 		return;
 	}
 
-	snprintf(tmp, sizeof(tmp), " %s%d: <%s:", state->name, origin, flavour);
-	strlcat(state->pp_buf, tmp, PAGE_SIZE);
+	seq_buf_printf(&state->pp_buf, " %s%d: <%s:", state->name, origin, flavour);
 
 	if (le16_to_cpu(l->d_npartitions) < max_partitions)
 		max_partitions = le16_to_cpu(l->d_npartitions);

@@ -391,18 +380,16 @@ static void parse_bsd(struct parsed_partitions *state,
 			/* full parent partition, we have it already */
 			continue;
 		if (offset > bsd_start || offset+size < bsd_start+bsd_size) {
-			strlcat(state->pp_buf, "bad subpartition - ignored\n", PAGE_SIZE);
+			seq_buf_puts(&state->pp_buf, "bad subpartition - ignored\n");
 			continue;
 		}
 		put_partition(state, state->next++, bsd_start, bsd_size);
 	}
 	put_dev_sector(sect);
-	if (le16_to_cpu(l->d_npartitions) > max_partitions) {
-		snprintf(tmp, sizeof(tmp), " (ignored %d more)",
-			 le16_to_cpu(l->d_npartitions) - max_partitions);
-		strlcat(state->pp_buf, tmp, PAGE_SIZE);
-	}
-	strlcat(state->pp_buf, " >\n", PAGE_SIZE);
+	if (le16_to_cpu(l->d_npartitions) > max_partitions)
+		seq_buf_printf(&state->pp_buf, " (ignored %d more)",
+			       le16_to_cpu(l->d_npartitions) - max_partitions);
+	seq_buf_puts(&state->pp_buf, " >\n");
 }
 #endif
 

@@ -496,12 +483,7 @@ static void parse_unixware(struct parsed_partitions *state,
 		put_dev_sector(sect);
 		return;
 	}
-	{
-		char tmp[1 + BDEVNAME_SIZE + 10 + 12 + 1];
-
-		snprintf(tmp, sizeof(tmp), " %s%d: <unixware:", state->name, origin);
-		strlcat(state->pp_buf, tmp, PAGE_SIZE);
-	}
+	seq_buf_printf(&state->pp_buf, " %s%d: <unixware:", state->name, origin);
 	p = &l->vtoc.v_slice[1];
 	/* I omit the 0th slice as it is the same as whole disk. */
 	while (p - &l->vtoc.v_slice[0] < UNIXWARE_NUMSLICE) {

@@ -515,7 +497,7 @@ static void parse_unixware(struct parsed_partitions *state,
 		p++;
 	}
 	put_dev_sector(sect);
-	strlcat(state->pp_buf, " >\n", PAGE_SIZE);
+	seq_buf_puts(&state->pp_buf, " >\n");
 #endif
 }
 

@@ -546,10 +528,7 @@ static void parse_minix(struct parsed_partitions *state,
 	 * the normal boot sector. */
 	if (msdos_magic_present(data + 510) &&
 	    p->sys_ind == MINIX_PARTITION) { /* subpartition table present */
-		char tmp[1 + BDEVNAME_SIZE + 10 + 9 + 1];
-
-		snprintf(tmp, sizeof(tmp), " %s%d: <minix:", state->name, origin);
-		strlcat(state->pp_buf, tmp, PAGE_SIZE);
+		seq_buf_printf(&state->pp_buf, " %s%d: <minix:", state->name, origin);
 		for (i = 0; i < MINIX_NR_SUBPARTITIONS; i++, p++) {
 			if (state->next == state->limit)
 				break;

@@ -558,7 +537,7 @@ static void parse_minix(struct parsed_partitions *state,
 				put_partition(state, state->next++,
 					      start_sect(p), nr_sects(p));
 		}
-		strlcat(state->pp_buf, " >\n", PAGE_SIZE);
+		seq_buf_puts(&state->pp_buf, " >\n");
 	}
 	put_dev_sector(sect);
 #endif /* CONFIG_MINIX_SUBPARTITION */

@@ -602,7 +581,7 @@ int msdos_partition(struct parsed_partitions *state)
 #ifdef CONFIG_AIX_PARTITION
 		return aix_partition(state);
 #else
-		strlcat(state->pp_buf, " [AIX]", PAGE_SIZE);
+		seq_buf_puts(&state->pp_buf, " [AIX]");
 		return 0;
 #endif
 	}

@@ -629,7 +608,7 @@ int msdos_partition(struct parsed_partitions *state)
 			fb = (struct fat_boot_sector *) data;
 			if (slot == 1 && fb->reserved && fb->fats
 				&& fat_valid_media(fb->media)) {
-				strlcat(state->pp_buf, "\n", PAGE_SIZE);
+				seq_buf_puts(&state->pp_buf, "\n");
 				put_dev_sector(sect);
 				return 1;
 			} else {

@@ -678,9 +657,9 @@ int msdos_partition(struct parsed_partitions *state)
 			n = min(size, max(sector_size, n));
 			put_partition(state, slot, start, n);
 
-			strlcat(state->pp_buf, " <", PAGE_SIZE);
+			seq_buf_puts(&state->pp_buf, " <");
 			parse_extended(state, start, size, disksig);
-			strlcat(state->pp_buf, " >", PAGE_SIZE);
+			seq_buf_puts(&state->pp_buf, " >");
 			continue;
 		}
 		put_partition(state, slot, start, size);

@@ -688,12 +667,12 @@ int msdos_partition(struct parsed_partitions *state)
 		if (p->sys_ind == LINUX_RAID_PARTITION)
 			state->parts[slot].flags = ADDPART_FLAG_RAID;
 		if (p->sys_ind == DM6_PARTITION)
-			strlcat(state->pp_buf, "[DM]", PAGE_SIZE);
+			seq_buf_puts(&state->pp_buf, "[DM]");
 		if (p->sys_ind == EZD_PARTITION)
-			strlcat(state->pp_buf, "[EZD]", PAGE_SIZE);
+			seq_buf_puts(&state->pp_buf, "[EZD]");
 	}
 
-	strlcat(state->pp_buf, "\n", PAGE_SIZE);
+	seq_buf_puts(&state->pp_buf, "\n");
 
 	/* second pass - output for each on a separate line */
 	p = (struct msdos_partition *) (0x1be + data);

block/partitions/of.c +2 -4

index 4e760fdffb3f..c22b60661098 100644
@@ -36,7 +36,6 @@ static void add_of_partition(struct parsed_partitions *state, int slot,
 			     struct device_node *np)
 {
 	struct partition_meta_info *info;
-	char tmp[sizeof(info->volname) + 4];
 	const char *partname;
 	int len;
 

@@ -63,8 +62,7 @@ static void add_of_partition(struct parsed_partitions *state, int slot,
 		partname = of_get_property(np, "name", &len);
 	strscpy(info->volname, partname, sizeof(info->volname));
 
-	snprintf(tmp, sizeof(tmp), "(%s)", info->volname);
-	strlcat(state->pp_buf, tmp, PAGE_SIZE);
+	seq_buf_printf(&state->pp_buf, "(%s)", info->volname);
 }
 
 int of_partition(struct parsed_partitions *state)

@@ -104,7 +102,7 @@ int of_partition(struct parsed_partitions *state)
 		slot++;
 	}
 
-	strlcat(state->pp_buf, "\n", PAGE_SIZE);
+	seq_buf_puts(&state->pp_buf, "\n");
 
 	return 1;
 }

block/partitions/osf.c +1 -1

index 84560d0765ed..2a692584dba9 100644
@@ -81,7 +81,7 @@ int osf_partition(struct parsed_partitions *state)
 				le32_to_cpu(partition->p_size));
 		slot++;
 	}
-	strlcat(state->pp_buf, "\n", PAGE_SIZE);
+	seq_buf_puts(&state->pp_buf, "\n");
 	put_dev_sector(sect);
 	return 1;
 }

block/partitions/sgi.c +1 -1

index b5ecddd5181a..2383ca63cd66 100644
@@ -79,7 +79,7 @@ int sgi_partition(struct parsed_partitions *state)
 		}
 		slot++;
 	}
-	strlcat(state->pp_buf, "\n", PAGE_SIZE);
+	seq_buf_puts(&state->pp_buf, "\n");
 	put_dev_sector(sect);
 	return 1;
 }

block/partitions/sun.c +1 -1

index 2419af76120f..92c645fcd2e0 100644
@@ -121,7 +121,7 @@ int sun_partition(struct parsed_partitions *state)
 		}
 		slot++;
 	}
-	strlcat(state->pp_buf, "\n", PAGE_SIZE);
+	seq_buf_puts(&state->pp_buf, "\n");
 	put_dev_sector(sect);
 	return 1;
 }

block/partitions/sysv68.c +3 -6

index 6f6257fd4eb4..470e0f9de7be 100644
@@ -54,7 +54,6 @@ int sysv68_partition(struct parsed_partitions *state)
 	unsigned char *data;
 	struct dkblk0 *b;
 	struct slice *slice;
-	char tmp[64];
 
 	data = read_part_sector(state, 0, &sect);
 	if (!data)

@@ -74,8 +73,7 @@ int sysv68_partition(struct parsed_partitions *state)
 		return -1;
 
 	slices -= 1; /* last slice is the whole disk */
-	snprintf(tmp, sizeof(tmp), "sysV68: %s(s%u)", state->name, slices);
-	strlcat(state->pp_buf, tmp, PAGE_SIZE);
+	seq_buf_printf(&state->pp_buf, "sysV68: %s(s%u)", state->name, slices);
 	slice = (struct slice *)data;
 	for (i = 0; i < slices; i++, slice++) {
 		if (slot == state->limit)

@@ -84,12 +82,11 @@ int sysv68_partition(struct parsed_partitions *state)
 			put_partition(state, slot,
 				be32_to_cpu(slice->blkoff),
 				be32_to_cpu(slice->nblocks));
-			snprintf(tmp, sizeof(tmp), "(s%u)", i);
-			strlcat(state->pp_buf, tmp, PAGE_SIZE);
+			seq_buf_printf(&state->pp_buf, "(s%u)", i);
 		}
 		slot++;
 	}
-	strlcat(state->pp_buf, "\n", PAGE_SIZE);
+	seq_buf_puts(&state->pp_buf, "\n");
 	put_dev_sector(sect);
 	return 1;
 }

block/partitions/ultrix.c +0 -0

index 4aaa81043ca0..b4b9ddc57a5d 100644

Reviewed-by Josh Law <[email protected]>

Quoted 1 line · Josh Law

Reviewed-by Josh Law <[email protected]>

Please don't quote 1000 lines just to add that, that's somewhat annoying in terms of scrolling to find wtf was said, and it's hugely wasteful. Prune your replies.

In preparation for removing the strlcat API[1], replace the char *pp_buf with a struct seq_buf, which tracks the current write position and remaining space internally. This allows for:

- Direct use of seq_buf_printf() in place of snprintf()+strlcat() pairs, eliminating local tmp buffers throughout.
- Adjacent strlcat() calls that build strings piece-by-piece (e.g., strlcat("["); strlcat(name); strlcat("]")) to be collapsed into single seq_buf_printf() calls.
- Simpler call sites: seq_buf_puts() takes only the buffer and string, with no need to pass PAGE_SIZE at every call.

[...]

In preparation for removing the strlcat API[1], replace the char *pp_buf with a struct seq_buf, which tracks the current write position and remaining space internally. This allows for:

- Direct use of seq_buf_printf() in place of snprintf()+strlcat() pairs, eliminating local tmp buffers throughout.

- Adjacent strlcat() calls that build strings piece-by-piece (e.g., strlcat("["); strlcat(name); strlcat("]")) to be collapsed into single seq_buf_printf() calls.
- Simpler call sites: seq_buf_puts() takes only the buffer and string, with no need to pass PAGE_SIZE at every call.

The backing buffer allocation is unchanged (__get_free_page),

and the
output path uses seq_buf_str() to NUL-terminate before passing to printk().

Link https://github.com/KSPP/linux/issues/370 [1]

Cc Andy Shevchenko <[email protected]>

Cc Josh Law <[email protected]>

Signed-off-by Kees Cook <[email protected]>

---
I couldn't help myself. Here's the full patch, as I suggested in
https://lore.kernel.org/lkml/202603201230.74BBFFABAD@keescook/
There are plenty more like this to do...

---
 block/partitions/check.h   |  8 ++---
 block/partitions/core.c    | 20 ++++++------
 block/partitions/acorn.c   | 32 ++++++++----------
 block/partitions/aix.c     | 21 +++++-------
 block/partitions/amiga.c   | 35 +++++++++-----------
 block/partitions/atari.c   | 12 +++----
 block/partitions/cmdline.c |  6 ++--
 block/partitions/efi.c     |  2 +-
 block/partitions/ibm.c     | 27 ++++++---------
 block/partitions/karma.c   |  2 +-
 block/partitions/ldm.c     |  4 +--
 block/partitions/mac.c     |  4 +--
 block/partitions/msdos.c   | 67 +++++++++++++-------------------------
 block/partitions/of.c      |  6 ++--
 block/partitions/osf.c     |  2 +-
 block/partitions/sgi.c     |  2 +-
 block/partitions/sun.c     |  2 +-
 block/partitions/sysv68.c  |  9 ++---
 block/partitions/ultrix.c  |  2 +-
 19 files changed, 106 insertions(+), 157 deletions(-)

block/partitions/check.h +3 -5

index e5c1c61eb353..b0997467b61a 100644
@@ -1,6 +1,7 @@
 /* SPDX-License-Identifier: GPL-2.0 */
 #include <linux/pagemap.h>
 #include <linux/blkdev.h>
+#include <linux/seq_buf.h>
 #include "../blk.h"
 
 /*

@@ -20,7 +21,7 @@ struct parsed_partitions {
 	int next;
 	int limit;
 	bool access_beyond_eod;
-	char *pp_buf;
+	struct seq_buf pp_buf;
 };
 
 typedef struct {

@@ -37,12 +38,9 @@ static inline void
 put_partition(struct parsed_partitions *p, int n, sector_t from, sector_t size)
 {
 	if (n < p->limit) {
-		char tmp[1 + BDEVNAME_SIZE + 10 + 1];
-
 		p->parts[n].from = from;
 		p->parts[n].size = size;
-		snprintf(tmp, sizeof(tmp), " %s%d", p->name, n);
-		strlcat(p->pp_buf, tmp, PAGE_SIZE);
+		seq_buf_printf(&p->pp_buf, " %s%d", p->name, n);
 	}
 }
 

block/partitions/core.c +6 -6

index 740228750aaf..3b5928836c69 100644
@@ -123,16 +123,16 @@ static struct parsed_partitions *check_partition(struct gendisk *hd)
 	state = allocate_partitions(hd);
 	if (!state)
 		return NULL;
-	state->pp_buf = (char *)__get_free_page(GFP_KERNEL);
-	if (!state->pp_buf) {
+	state->pp_buf.buffer = (char *)__get_free_page(GFP_KERNEL);
+	if (!state->pp_buf.buffer) {
 		free_partitions(state);
 		return NULL;
 	}
-	state->pp_buf[0] = '\0';
+	seq_buf_init(&state->pp_buf, state->pp_buf.buffer, PAGE_SIZE);
 
 	state->disk = hd;
 	strscpy(state->name, hd->disk_name);
-	snprintf(state->pp_buf, PAGE_SIZE, " %s:", state->name);
+	seq_buf_printf(&state->pp_buf, " %s:", state->name);
 	if (isdigit(state->name[strlen(state->name)-1]))
 		sprintf(state->name, "p");
 

@@ -151,9 +151,9 @@ static struct parsed_partitions *check_partition(struct gendisk *hd)
 
 	}
 	if (res > 0) {
-		printk(KERN_INFO "%s", state->pp_buf);
+		printk(KERN_INFO "%s", seq_buf_str(&state->pp_buf));
 
-		free_page((unsigned long)state->pp_buf);
+		free_page((unsigned long)state->pp_buf.buffer);
 		return state;
 	}
 	if (state->access_beyond_eod)

block/partitions/core.c +1 -1

 	}
 
-	free_page((unsigned long)state->pp_buf);
+	free_page((unsigned long)state->pp_buf.buffer);
 	free_partitions(state);
 	return ERR_PTR(res);
 }

block/partitions/acorn.c +14 -18

index d2fc122d7426..9f7389f174d0 100644
@@ -40,9 +40,7 @@ adfs_partition(struct parsed_partitions *state, char *name, char *data,
 		   (le32_to_cpu(dr->disc_size) >> 9);
 
 	if (name) {
-		strlcat(state->pp_buf, " [", PAGE_SIZE);
-		strlcat(state->pp_buf, name, PAGE_SIZE);
-		strlcat(state->pp_buf, "]", PAGE_SIZE);
+		seq_buf_printf(&state->pp_buf, " [%s]", name);
 	}
 	put_partition(state, slot, first_sector, nr_sects);
 	return dr;

@@ -78,14 +76,14 @@ static int riscix_partition(struct parsed_partitions *state,
 	if (!rr)
 		return -1;
 
-	strlcat(state->pp_buf, " [RISCiX]", PAGE_SIZE);
+	seq_buf_puts(&state->pp_buf, " [RISCiX]");
 
 
 	if (rr->magic == RISCIX_MAGIC) {
 		unsigned long size = nr_sects > 2 ? 2 : nr_sects;
 		int part;
 
-		strlcat(state->pp_buf, " <", PAGE_SIZE);
+		seq_buf_puts(&state->pp_buf, " <");
 
 		put_partition(state, slot++, first_sect, size);
 		for (part = 0; part < 8; part++) {

@@ -94,13 +92,11 @@ static int riscix_partition(struct parsed_partitions *state,
 				put_partition(state, slot++,
 					le32_to_cpu(rr->part[part].start),
 					le32_to_cpu(rr->part[part].length));
-				strlcat(state->pp_buf, "(", PAGE_SIZE);
-				strlcat(state->pp_buf, rr->part[part].name, PAGE_SIZE);
-				strlcat(state->pp_buf, ")", PAGE_SIZE);
+				seq_buf_printf(&state->pp_buf, "(%s)", rr->part[part].name);
 			}
 		}
 
-		strlcat(state->pp_buf, " >\n", PAGE_SIZE);
+		seq_buf_puts(&state->pp_buf, " >\n");
 	} else {
 		put_partition(state, slot++, first_sect, nr_sects);
 	}

@@ -130,7 +126,7 @@ static int linux_partition(struct parsed_partitions *state,
 	struct linux_part *linuxp;
 	unsigned long size = nr_sects > 2 ? 2 : nr_sects;
 
-	strlcat(state->pp_buf, " [Linux]", PAGE_SIZE);
+	seq_buf_puts(&state->pp_buf, " [Linux]");
 
 	put_partition(state, slot++, first_sect, size);
 

@@ -138,7 +134,7 @@ static int linux_partition(struct parsed_partitions *state,
 	if (!linuxp)
 		return -1;
 
-	strlcat(state->pp_buf, " <", PAGE_SIZE);
+	seq_buf_puts(&state->pp_buf, " <");
 	while (linuxp->magic == cpu_to_le32(LINUX_NATIVE_MAGIC) ||
 	       linuxp->magic == cpu_to_le32(LINUX_SWAP_MAGIC)) {
 		if (slot == state->limit)

@@ -148,7 +144,7 @@ static int linux_partition(struct parsed_partitions *state,
 				 le32_to_cpu(linuxp->nr_sects));
 		linuxp ++;
 	}
-	strlcat(state->pp_buf, " >", PAGE_SIZE);
+	seq_buf_puts(&state->pp_buf, " >");
 
 	put_dev_sector(sect);
 	return slot;

@@ -293,7 +289,7 @@ int adfspart_check_ADFS(struct parsed_partitions *state)
 			break;
 		}
 	}
-	strlcat(state->pp_buf, "\n", PAGE_SIZE);
+	seq_buf_puts(&state->pp_buf, "\n");
 	return 1;
 }
 #endif

@@ -366,7 +362,7 @@ int adfspart_check_ICS(struct parsed_partitions *state)
 		return 0;
 	}
 
-	strlcat(state->pp_buf, " [ICS]", PAGE_SIZE);
+	seq_buf_puts(&state->pp_buf, " [ICS]");
 
 	for (slot = 1, p = (const struct ics_part *)data; p->size; p++) {
 		u32 start = le32_to_cpu(p->start);

@@ -400,7 +396,7 @@ int adfspart_check_ICS(struct parsed_partitions *state)
 	}
 
 	put_dev_sector(sect);
-	strlcat(state->pp_buf, "\n", PAGE_SIZE);
+	seq_buf_puts(&state->pp_buf, "\n");
 	return 1;
 }
 #endif

@@ -460,7 +456,7 @@ int adfspart_check_POWERTEC(struct parsed_partitions *state)
 		return 0;
 	}
 
-	strlcat(state->pp_buf, " [POWERTEC]", PAGE_SIZE);
+	seq_buf_puts(&state->pp_buf, " [POWERTEC]");
 
 	for (i = 0, p = (const struct ptec_part *)data; i < 12; i++, p++) {
 		u32 start = le32_to_cpu(p->start);

@@ -471,7 +467,7 @@ int adfspart_check_POWERTEC(struct parsed_partitions *state)
 	}
 
 	put_dev_sector(sect);
-	strlcat(state->pp_buf, "\n", PAGE_SIZE);
+	seq_buf_puts(&state->pp_buf, "\n");
 	return 1;
 }
 #endif

@@ -542,7 +538,7 @@ int adfspart_check_EESOX(struct parsed_partitions *state)
 
 		size = get_capacity(state->disk);
 		put_partition(state, slot++, start, size - start);
-		strlcat(state->pp_buf, "\n", PAGE_SIZE);
+		seq_buf_puts(&state->pp_buf, "\n");
 	}
 
 	return i ? 1 : 0;

block/partitions/aix.c +8 -13

index a886cefbefbb..29b8f4cebb63 100644
@@ -173,24 +173,22 @@ int aix_partition(struct parsed_partitions *state)
 	if (d) {
 		struct lvm_rec *p = (struct lvm_rec *)d;
 		u16 lvm_version = be16_to_cpu(p->version);
-		char tmp[64];
 
 		if (lvm_version == 1) {
 			int pp_size_log2 = be16_to_cpu(p->pp_size);
 
 			pp_bytes_size = 1 << pp_size_log2;
 			pp_blocks_size = pp_bytes_size / 512;
-			snprintf(tmp, sizeof(tmp),
-				" AIX LVM header version %u found\n",
-				lvm_version);
+			seq_buf_printf(&state->pp_buf,
+				       " AIX LVM header version %u found\n",
+				       lvm_version);
 			vgda_len = be32_to_cpu(p->vgda_len);
 			vgda_sector = be32_to_cpu(p->vgda_psn[0]);
 		} else {
-			snprintf(tmp, sizeof(tmp),
-				" unsupported AIX LVM version %d found\n",
-				lvm_version);
+			seq_buf_printf(&state->pp_buf,
+				       " unsupported AIX LVM version %d found\n",
+				       lvm_version);
 		}
-		strlcat(state->pp_buf, tmp, PAGE_SIZE);
 		put_dev_sector(sect);
 	}
 	if (vgda_sector && (d = read_part_sector(state, vgda_sector, &sect))) {

@@ -251,14 +249,11 @@ int aix_partition(struct parsed_partitions *state)
 				continue;
 			}
 			if (lp_ix == lvip[lv_ix].pps_per_lv) {
-				char tmp[70];
-
 				put_partition(state, lv_ix + 1,
 				  (i + 1 - lp_ix) * pp_blocks_size + psn_part1,
 				  lvip[lv_ix].pps_per_lv * pp_blocks_size);
-				snprintf(tmp, sizeof(tmp), " <%s>\n",
-					 n[lv_ix].name);
-				strlcat(state->pp_buf, tmp, PAGE_SIZE);
+				seq_buf_printf(&state->pp_buf, " <%s>\n",
+					       n[lv_ix].name);
 				lvip[lv_ix].lv_is_contiguous = 1;
 				ret = 1;
 				next_lp_ix = 1;

block/partitions/amiga.c +15 -20

index 506921095412..8325046a14eb 100644
@@ -81,13 +81,8 @@ int amiga_partition(struct parsed_partitions *state)
 	/* blksize is blocks per 512 byte standard block */
 	blksize = be32_to_cpu( rdb->rdb_BlockBytes ) / 512;
 
-	{
-		char tmp[7 + 10 + 1 + 1];
-
-		/* Be more informative */
-		snprintf(tmp, sizeof(tmp), " RDSK (%d)", blksize * 512);
-		strlcat(state->pp_buf, tmp, PAGE_SIZE);
-	}
+	/* Be more informative */
+	seq_buf_printf(&state->pp_buf, " RDSK (%d)", blksize * 512);
 	blk = be32_to_cpu(rdb->rdb_PartitionList);
 	put_dev_sector(sect);
 	for (part = 1; (s32) blk>0 && part<=16; part++, put_dev_sector(sect)) {

@@ -179,27 +174,27 @@ int amiga_partition(struct parsed_partitions *state)
 		{
 			/* Be even more informative to aid mounting */
 			char dostype[4];
-			char tmp[42];
 
 			__be32 *dt = (__be32 *)dostype;
 			*dt = pb->pb_Environment[16];
 			if (dostype[3] < ' ')
-				snprintf(tmp, sizeof(tmp), " (%c%c%c^%c)",
-					dostype[0], dostype[1],
-					dostype[2], dostype[3] + '@' );
+				seq_buf_printf(&state->pp_buf,
+					       " (%c%c%c^%c)",
+					       dostype[0], dostype[1],
+					       dostype[2],
+					       dostype[3] + '@');
 			else
-				snprintf(tmp, sizeof(tmp), " (%c%c%c%c)",
-					dostype[0], dostype[1],
-					dostype[2], dostype[3]);
-			strlcat(state->pp_buf, tmp, PAGE_SIZE);
-			snprintf(tmp, sizeof(tmp), "(res %d spb %d)",
-				be32_to_cpu(pb->pb_Environment[6]),
-				be32_to_cpu(pb->pb_Environment[4]));
-			strlcat(state->pp_buf, tmp, PAGE_SIZE);
+				seq_buf_printf(&state->pp_buf,
+					       " (%c%c%c%c)",
+					       dostype[0], dostype[1],
+					       dostype[2], dostype[3]);
+			seq_buf_printf(&state->pp_buf, "(res %d spb %d)",
+				       be32_to_cpu(pb->pb_Environment[6]),
+				       be32_to_cpu(pb->pb_Environment[4]));
 		}
 		res = 1;
 	}
-	strlcat(state->pp_buf, "\n", PAGE_SIZE);
+	seq_buf_puts(&state->pp_buf, "\n");
 
 rdb_done:
 	return res;

block/partitions/atari.c +6 -6

index 9655c728262a..2438d1448f38 100644
@@ -70,7 +70,7 @@ int atari_partition(struct parsed_partitions *state)
 	}
 
 	pi = &rs->part[0];
-	strlcat(state->pp_buf, " AHDI", PAGE_SIZE);
+	seq_buf_puts(&state->pp_buf, " AHDI");
 	for (slot = 1; pi < &rs->part[4] && slot < state->limit; slot++, pi++) {
 		struct rootsector *xrs;
 		Sector sect2;

@@ -89,7 +89,7 @@ int atari_partition(struct parsed_partitions *state)
 #ifdef ICD_PARTS
 		part_fmt = 1;
 #endif
-		strlcat(state->pp_buf, " XGM<", PAGE_SIZE);
+		seq_buf_puts(&state->pp_buf, " XGM<");
 		partsect = extensect = be32_to_cpu(pi->st);
 		while (1) {
 			xrs = read_part_sector(state, partsect, &sect2);

@@ -128,14 +128,14 @@ int atari_partition(struct parsed_partitions *state)
 				break;
 			}
 		}
-		strlcat(state->pp_buf, " >", PAGE_SIZE);
+		seq_buf_puts(&state->pp_buf, " >");
 	}
 #ifdef ICD_PARTS
 	if ( part_fmt!=1 ) { /* no extended partitions -> test ICD-format */
 		pi = &rs->icdpart[0];
 		/* sanity check: no ICD format if first partition invalid */
 		if (OK_id(pi->id)) {
-			strlcat(state->pp_buf, " ICD<", PAGE_SIZE);
+			seq_buf_puts(&state->pp_buf, " ICD<");
 			for (; pi < &rs->icdpart[8] && slot < state->limit; slot++, pi++) {
 				/* accept only GEM,BGM,RAW,LNX,SWP partitions */
 				if (!((pi->flg & 1) && OK_id(pi->id)))

@@ -144,13 +144,13 @@ int atari_partition(struct parsed_partitions *state)
 						be32_to_cpu(pi->st),
 						be32_to_cpu(pi->siz));
 			}
-			strlcat(state->pp_buf, " >", PAGE_SIZE);
+			seq_buf_puts(&state->pp_buf, " >");
 		}
 	}
 #endif
 	put_dev_sector(sect);
 
-	strlcat(state->pp_buf, "\n", PAGE_SIZE);
+	seq_buf_puts(&state->pp_buf, "\n");
 
 	return 1;
 }

block/partitions/cmdline.c +2 -4

index a2b1870c3fd4..4fd52ed154b4 100644
@@ -229,7 +229,6 @@ static int add_part(int slot, struct cmdline_subpart *subpart,
 		struct parsed_partitions *state)
 {
 	struct partition_meta_info *info;
-	char tmp[sizeof(info->volname) + 4];
 
 	if (slot >= state->limit)
 		return 1;

@@ -244,8 +243,7 @@ static int add_part(int slot, struct cmdline_subpart *subpart,
 
 	strscpy(info->volname, subpart->name, sizeof(info->volname));
 
-	snprintf(tmp, sizeof(tmp), "(%s)", info->volname);
-	strlcat(state->pp_buf, tmp, PAGE_SIZE);
+	seq_buf_printf(&state->pp_buf, "(%s)", info->volname);
 
 	state->parts[slot].has_info = true;
 

@@ -379,7 +377,7 @@ int cmdline_partition(struct parsed_partitions *state)
 	cmdline_parts_set(parts, disk_size, state);
 	cmdline_parts_verifier(1, state);
 
-	strlcat(state->pp_buf, "\n", PAGE_SIZE);
+	seq_buf_puts(&state->pp_buf, "\n");
 
 	return 1;
 }

block/partitions/efi.c +1 -1

index 75474fb3848e..9865d59093fa 100644
@@ -751,6 +751,6 @@ int efi_partition(struct parsed_partitions *state)
 	}
 	kfree(ptes);
 	kfree(gpt);
-	strlcat(state->pp_buf, "\n", PAGE_SIZE);
+	seq_buf_puts(&state->pp_buf, "\n");
 	return 1;
 }

block/partitions/ibm.c +10 -17

index 9311ad5fb95d..54047e722a9d 100644
@@ -173,15 +173,13 @@ static int find_vol1_partitions(struct parsed_partitions *state,
 {
 	sector_t blk;
 	int counter;
-	char tmp[64];
 	Sector sect;
 	unsigned char *data;
 	loff_t offset, size;
 	struct vtoc_format1_label f1;
 	int secperblk;
 
-	snprintf(tmp, sizeof(tmp), "VOL1/%8s:", name);
-	strlcat(state->pp_buf, tmp, PAGE_SIZE);
+	seq_buf_printf(&state->pp_buf, "VOL1/%8s:", name);
 	/*
 	 * get start of VTOC from the disk label and then search for format1
 	 * and format8 labels

@@ -219,7 +217,7 @@ static int find_vol1_partitions(struct parsed_partitions *state,
 		blk++;
 		data = read_part_sector(state, blk * secperblk, &sect);
 	}
-	strlcat(state->pp_buf, "\n", PAGE_SIZE);
+	seq_buf_puts(&state->pp_buf, "\n");
 
 	if (!data)
 		return -1;

@@ -237,11 +235,9 @@ static int find_lnx1_partitions(struct parsed_partitions *state,
 				dasd_information2_t *info)
 {
 	loff_t offset, geo_size, size;
-	char tmp[64];
 	int secperblk;
 
-	snprintf(tmp, sizeof(tmp), "LNX1/%8s:", name);
-	strlcat(state->pp_buf, tmp, PAGE_SIZE);
+	seq_buf_printf(&state->pp_buf, "LNX1/%8s:", name);
 	secperblk = blocksize >> 9;
 	if (label->lnx.ldl_version == 0xf2) {
 		size = label->lnx.formatted_blocks * secperblk;

@@ -258,7 +254,7 @@ static int find_lnx1_partitions(struct parsed_partitions *state,
 		size = nr_sectors;
 		if (size != geo_size) {
 			if (!info) {
-				strlcat(state->pp_buf, "\n", PAGE_SIZE);
+				seq_buf_puts(&state->pp_buf, "\n");
 				return 1;
 			}
 			if (!strcmp(info->type, "ECKD"))

@@ -270,7 +266,7 @@ static int find_lnx1_partitions(struct parsed_partitions *state,
 	/* first and only partition starts in the first block after the label */
 	offset = labelsect + secperblk;
 	put_partition(state, 1, offset, size - offset);
-	strlcat(state->pp_buf, "\n", PAGE_SIZE);
+	seq_buf_puts(&state->pp_buf, "\n");
 	return 1;
 }
 

@@ -282,7 +278,6 @@ static int find_cms1_partitions(struct parsed_partitions *state,
 				sector_t labelsect)
 {
 	loff_t offset, size;
-	char tmp[64];
 	int secperblk;
 
 	/*

@@ -291,14 +286,12 @@ static int find_cms1_partitions(struct parsed_partitions *state,
 	blocksize = label->cms.block_size;
 	secperblk = blocksize >> 9;
 	if (label->cms.disk_offset != 0) {
-		snprintf(tmp, sizeof(tmp), "CMS1/%8s(MDSK):", name);
-		strlcat(state->pp_buf, tmp, PAGE_SIZE);
+		seq_buf_printf(&state->pp_buf, "CMS1/%8s(MDSK):", name);
 		/* disk is reserved minidisk */
 		offset = label->cms.disk_offset * secperblk;
 		size = (label->cms.block_count - 1) * secperblk;
 	} else {
-		snprintf(tmp, sizeof(tmp), "CMS1/%8s:", name);
-		strlcat(state->pp_buf, tmp, PAGE_SIZE);
+		seq_buf_printf(&state->pp_buf, "CMS1/%8s:", name);
 		/*
 		 * Special case for FBA devices:
 		 * If an FBA device is CMS formatted with blocksize > 512 byte

@@ -314,7 +307,7 @@ static int find_cms1_partitions(struct parsed_partitions *state,
 	}
 
 	put_partition(state, 1, offset, size-offset);
-	strlcat(state->pp_buf, "\n", PAGE_SIZE);
+	seq_buf_puts(&state->pp_buf, "\n");
 	return 1;
 }
 

@@ -391,11 +384,11 @@ int ibm_partition(struct parsed_partitions *state)
 		 */
 		res = 1;
 		if (info->format == DASD_FORMAT_LDL) {
-			strlcat(state->pp_buf, "(nonl)", PAGE_SIZE);
+			seq_buf_puts(&state->pp_buf, "(nonl)");
 			size = nr_sectors;
 			offset = (info->label_block + 1) * (blocksize >> 9);
 			put_partition(state, 1, offset, size-offset);
-			strlcat(state->pp_buf, "\n", PAGE_SIZE);
+			seq_buf_puts(&state->pp_buf, "\n");
 		}
 	} else
 		res = 0;

block/partitions/karma.c +1 -1

index 4d93512f4bd4..a4e3c5050177 100644
@@ -53,7 +53,7 @@ int karma_partition(struct parsed_partitions *state)
 		}
 		slot++;
 	}
-	strlcat(state->pp_buf, "\n", PAGE_SIZE);
+	seq_buf_puts(&state->pp_buf, "\n");
 	put_dev_sector(sect);
 	return 1;
 }

block/partitions/ldm.c +2 -2

index 776b4ad95091..c0bdcae58a3e 100644
@@ -582,7 +582,7 @@ static bool ldm_create_data_partitions (struct parsed_partitions *pp,
 		return false;
 	}
 
-	strlcat(pp->pp_buf, " [LDM]", PAGE_SIZE);
+	seq_buf_puts(&pp->pp_buf, " [LDM]");
 
 	/* Create the data partitions */
 	list_for_each (item, &ldb->v_part) {

@@ -597,7 +597,7 @@ static bool ldm_create_data_partitions (struct parsed_partitions *pp,
 		part_num++;
 	}
 
-	strlcat(pp->pp_buf, "\n", PAGE_SIZE);
+	seq_buf_puts(&pp->pp_buf, "\n");
 	return true;
 }
 

block/partitions/mac.c +2 -2

index b02530d98629..df03ca428e15 100644
@@ -86,7 +86,7 @@ int mac_partition(struct parsed_partitions *state)
 	if (blocks_in_map >= state->limit)
 		blocks_in_map = state->limit - 1;
 
-	strlcat(state->pp_buf, " [mac]", PAGE_SIZE);
+	seq_buf_puts(&state->pp_buf, " [mac]");
 	for (slot = 1; slot <= blocks_in_map; ++slot) {
 		int pos = slot * secsize;
 		put_dev_sector(sect);

@@ -152,6 +152,6 @@ int mac_partition(struct parsed_partitions *state)
 #endif
 
 	put_dev_sector(sect);
-	strlcat(state->pp_buf, "\n", PAGE_SIZE);
+	seq_buf_puts(&state->pp_buf, "\n");
 	return 1;
 }

block/partitions/msdos.c +23 -44

index 073be78ba0b0..200ea53ea6a2 100644
@@ -263,18 +263,11 @@ static void parse_solaris_x86(struct parsed_partitions *state,
 		put_dev_sector(sect);
 		return;
 	}
-	{
-		char tmp[1 + BDEVNAME_SIZE + 10 + 11 + 1];
-
-		snprintf(tmp, sizeof(tmp), " %s%d: <solaris:", state->name, origin);
-		strlcat(state->pp_buf, tmp, PAGE_SIZE);
-	}
+	seq_buf_printf(&state->pp_buf, " %s%d: <solaris:", state->name, origin);
 	if (le32_to_cpu(v->v_version) != 1) {
-		char tmp[64];
-
-		snprintf(tmp, sizeof(tmp), "  cannot handle version %d vtoc>\n",
-			 le32_to_cpu(v->v_version));
-		strlcat(state->pp_buf, tmp, PAGE_SIZE);
+		seq_buf_printf(&state->pp_buf,
+			       "  cannot handle version %d vtoc>\n",
+			       le32_to_cpu(v->v_version));
 		put_dev_sector(sect);
 		return;
 	}

@@ -282,12 +275,10 @@ static void parse_solaris_x86(struct parsed_partitions *state,
 	max_nparts = le16_to_cpu(v->v_nparts) > 8 ? SOLARIS_X86_NUMSLICE : 8;
 	for (i = 0; i < max_nparts && state->next < state->limit; i++) {
 		struct solaris_x86_slice *s = &v->v_slice[i];
-		char tmp[3 + 10 + 1 + 1];
 
 		if (s->s_size == 0)
 			continue;
-		snprintf(tmp, sizeof(tmp), " [s%d]", i);
-		strlcat(state->pp_buf, tmp, PAGE_SIZE);
+		seq_buf_printf(&state->pp_buf, " [s%d]", i);
 		/* solaris partitions are relative to current MS-DOS
 		 * one; must add the offset of the current partition */
 		put_partition(state, state->next++,

@@ -295,7 +286,7 @@ static void parse_solaris_x86(struct parsed_partitions *state,
 				 le32_to_cpu(s->s_size));
 	}
 	put_dev_sector(sect);
-	strlcat(state->pp_buf, " >\n", PAGE_SIZE);
+	seq_buf_puts(&state->pp_buf, " >\n");
 #endif
 }
 

@@ -359,7 +350,6 @@ static void parse_bsd(struct parsed_partitions *state,
 	Sector sect;
 	struct bsd_disklabel *l;
 	struct bsd_partition *p;
-	char tmp[64];
 
 	l = read_part_sector(state, offset + 1, &sect);
 	if (!l)

@@ -369,8 +359,7 @@ static void parse_bsd(struct parsed_partitions *state,
 		return;
 	}
 
-	snprintf(tmp, sizeof(tmp), " %s%d: <%s:", state->name, origin, flavour);
-	strlcat(state->pp_buf, tmp, PAGE_SIZE);
+	seq_buf_printf(&state->pp_buf, " %s%d: <%s:", state->name, origin, flavour);
 
 	if (le16_to_cpu(l->d_npartitions) < max_partitions)
 		max_partitions = le16_to_cpu(l->d_npartitions);

@@ -391,18 +380,16 @@ static void parse_bsd(struct parsed_partitions *state,
 			/* full parent partition, we have it already */
 			continue;
 		if (offset > bsd_start || offset+size < bsd_start+bsd_size) {
-			strlcat(state->pp_buf, "bad subpartition - ignored\n", PAGE_SIZE);
+			seq_buf_puts(&state->pp_buf, "bad subpartition - ignored\n");
 			continue;
 		}
 		put_partition(state, state->next++, bsd_start, bsd_size);
 	}
 	put_dev_sector(sect);
-	if (le16_to_cpu(l->d_npartitions) > max_partitions) {
-		snprintf(tmp, sizeof(tmp), " (ignored %d more)",
-			 le16_to_cpu(l->d_npartitions) - max_partitions);
-		strlcat(state->pp_buf, tmp, PAGE_SIZE);
-	}
-	strlcat(state->pp_buf, " >\n", PAGE_SIZE);
+	if (le16_to_cpu(l->d_npartitions) > max_partitions)
+		seq_buf_printf(&state->pp_buf, " (ignored %d more)",
+			       le16_to_cpu(l->d_npartitions) - max_partitions);
+	seq_buf_puts(&state->pp_buf, " >\n");
 }
 #endif
 

@@ -496,12 +483,7 @@ static void parse_unixware(struct parsed_partitions *state,
 		put_dev_sector(sect);
 		return;
 	}
-	{
-		char tmp[1 + BDEVNAME_SIZE + 10 + 12 + 1];
-
-		snprintf(tmp, sizeof(tmp), " %s%d: <unixware:", state->name, origin);
-		strlcat(state->pp_buf, tmp, PAGE_SIZE);
-	}
+	seq_buf_printf(&state->pp_buf, " %s%d: <unixware:", state->name, origin);
 	p = &l->vtoc.v_slice[1];
 	/* I omit the 0th slice as it is the same as whole disk. */
 	while (p - &l->vtoc.v_slice[0] < UNIXWARE_NUMSLICE) {

@@ -515,7 +497,7 @@ static void parse_unixware(struct parsed_partitions *state,
 		p++;
 	}
 	put_dev_sector(sect);
-	strlcat(state->pp_buf, " >\n", PAGE_SIZE);
+	seq_buf_puts(&state->pp_buf, " >\n");
 #endif
 }
 

@@ -546,10 +528,7 @@ static void parse_minix(struct parsed_partitions *state,
 	 * the normal boot sector. */
 	if (msdos_magic_present(data + 510) &&
 	    p->sys_ind == MINIX_PARTITION) { /* subpartition table present */
-		char tmp[1 + BDEVNAME_SIZE + 10 + 9 + 1];
-
-		snprintf(tmp, sizeof(tmp), " %s%d: <minix:", state->name, origin);
-		strlcat(state->pp_buf, tmp, PAGE_SIZE);
+		seq_buf_printf(&state->pp_buf, " %s%d: <minix:", state->name, origin);
 		for (i = 0; i < MINIX_NR_SUBPARTITIONS; i++, p++) {
 			if (state->next == state->limit)
 				break;

@@ -558,7 +537,7 @@ static void parse_minix(struct parsed_partitions *state,
 				put_partition(state, state->next++,
 					      start_sect(p), nr_sects(p));
 		}
-		strlcat(state->pp_buf, " >\n", PAGE_SIZE);
+		seq_buf_puts(&state->pp_buf, " >\n");
 	}
 	put_dev_sector(sect);
 #endif /* CONFIG_MINIX_SUBPARTITION */

@@ -602,7 +581,7 @@ int msdos_partition(struct parsed_partitions *state)
 #ifdef CONFIG_AIX_PARTITION
 		return aix_partition(state);
 #else
-		strlcat(state->pp_buf, " [AIX]", PAGE_SIZE);
+		seq_buf_puts(&state->pp_buf, " [AIX]");
 		return 0;
 #endif
 	}

@@ -629,7 +608,7 @@ int msdos_partition(struct parsed_partitions *state)
 			fb = (struct fat_boot_sector *) data;
 			if (slot == 1 && fb->reserved && fb->fats
 				&& fat_valid_media(fb->media)) {
-				strlcat(state->pp_buf, "\n", PAGE_SIZE);
+				seq_buf_puts(&state->pp_buf, "\n");
 				put_dev_sector(sect);
 				return 1;
 			} else {

@@ -678,9 +657,9 @@ int msdos_partition(struct parsed_partitions *state)
 			n = min(size, max(sector_size, n));
 			put_partition(state, slot, start, n);
 
-			strlcat(state->pp_buf, " <", PAGE_SIZE);
+			seq_buf_puts(&state->pp_buf, " <");
 			parse_extended(state, start, size, disksig);
-			strlcat(state->pp_buf, " >", PAGE_SIZE);
+			seq_buf_puts(&state->pp_buf, " >");
 			continue;
 		}
 		put_partition(state, slot, start, size);

@@ -688,12 +667,12 @@ int msdos_partition(struct parsed_partitions *state)
 		if (p->sys_ind == LINUX_RAID_PARTITION)
 			state->parts[slot].flags = ADDPART_FLAG_RAID;
 		if (p->sys_ind == DM6_PARTITION)
-			strlcat(state->pp_buf, "[DM]", PAGE_SIZE);
+			seq_buf_puts(&state->pp_buf, "[DM]");
 		if (p->sys_ind == EZD_PARTITION)
-			strlcat(state->pp_buf, "[EZD]", PAGE_SIZE);
+			seq_buf_puts(&state->pp_buf, "[EZD]");
 	}
 
-	strlcat(state->pp_buf, "\n", PAGE_SIZE);
+	seq_buf_puts(&state->pp_buf, "\n");
 
 	/* second pass - output for each on a separate line */
 	p = (struct msdos_partition *) (0x1be + data);

block/partitions/of.c +2 -4

index 4e760fdffb3f..c22b60661098 100644
@@ -36,7 +36,6 @@ static void add_of_partition(struct parsed_partitions *state, int slot,
 			     struct device_node *np)
 {
 	struct partition_meta_info *info;
-	char tmp[sizeof(info->volname) + 4];
 	const char *partname;
 	int len;
 

@@ -63,8 +62,7 @@ static void add_of_partition(struct parsed_partitions *state, int slot,
 		partname = of_get_property(np, "name", &len);
 	strscpy(info->volname, partname, sizeof(info->volname));
 
-	snprintf(tmp, sizeof(tmp), "(%s)", info->volname);
-	strlcat(state->pp_buf, tmp, PAGE_SIZE);
+	seq_buf_printf(&state->pp_buf, "(%s)", info->volname);
 }
 
 int of_partition(struct parsed_partitions *state)

@@ -104,7 +102,7 @@ int of_partition(struct parsed_partitions *state)
 		slot++;
 	}
 
-	strlcat(state->pp_buf, "\n", PAGE_SIZE);
+	seq_buf_puts(&state->pp_buf, "\n");
 
 	return 1;
 }

block/partitions/osf.c +1 -1

index 84560d0765ed..2a692584dba9 100644
@@ -81,7 +81,7 @@ int osf_partition(struct parsed_partitions *state)
 				le32_to_cpu(partition->p_size));
 		slot++;
 	}
-	strlcat(state->pp_buf, "\n", PAGE_SIZE);
+	seq_buf_puts(&state->pp_buf, "\n");
 	put_dev_sector(sect);
 	return 1;
 }

block/partitions/sgi.c +1 -1

index b5ecddd5181a..2383ca63cd66 100644
@@ -79,7 +79,7 @@ int sgi_partition(struct parsed_partitions *state)
 		}
 		slot++;
 	}
-	strlcat(state->pp_buf, "\n", PAGE_SIZE);
+	seq_buf_puts(&state->pp_buf, "\n");
 	put_dev_sector(sect);
 	return 1;
 }

block/partitions/sun.c +1 -1

index 2419af76120f..92c645fcd2e0 100644
@@ -121,7 +121,7 @@ int sun_partition(struct parsed_partitions *state)
 		}
 		slot++;
 	}
-	strlcat(state->pp_buf, "\n", PAGE_SIZE);
+	seq_buf_puts(&state->pp_buf, "\n");
 	put_dev_sector(sect);
 	return 1;
 }

block/partitions/sysv68.c +3 -6

index 6f6257fd4eb4..470e0f9de7be 100644
@@ -54,7 +54,6 @@ int sysv68_partition(struct parsed_partitions *state)
 	unsigned char *data;
 	struct dkblk0 *b;
 	struct slice *slice;
-	char tmp[64];
 
 	data = read_part_sector(state, 0, &sect);
 	if (!data)

@@ -74,8 +73,7 @@ int sysv68_partition(struct parsed_partitions *state)
 		return -1;
 
 	slices -= 1; /* last slice is the whole disk */
-	snprintf(tmp, sizeof(tmp), "sysV68: %s(s%u)", state->name, slices);
-	strlcat(state->pp_buf, tmp, PAGE_SIZE);
+	seq_buf_printf(&state->pp_buf, "sysV68: %s(s%u)", state->name, slices);
 	slice = (struct slice *)data;
 	for (i = 0; i < slices; i++, slice++) {
 		if (slot == state->limit)

@@ -84,12 +82,11 @@ int sysv68_partition(struct parsed_partitions *state)
 			put_partition(state, slot,
 				be32_to_cpu(slice->blkoff),
 				be32_to_cpu(slice->nblocks));
-			snprintf(tmp, sizeof(tmp), "(s%u)", i);
-			strlcat(state->pp_buf, tmp, PAGE_SIZE);
+			seq_buf_printf(&state->pp_buf, "(s%u)", i);
 		}
 		slot++;
 	}
-	strlcat(state->pp_buf, "\n", PAGE_SIZE);
+	seq_buf_puts(&state->pp_buf, "\n");
 	put_dev_sector(sect);
 	return 1;
 }

block/partitions/ultrix.c +1 -1

index 4aaa81043ca0..b4b9ddc57a5d 100644
@@ -39,7 +39,7 @@ int ultrix_partition(struct parsed_partitions *state)
 					      label->pt_part[i].pi_blkoff,
 					      label->pt_part[i].pi_nblocks);
 		put_dev_sector(sect);
-		strlcat(state->pp_buf, "\n", PAGE_SIZE);
+		seq_buf_puts(&state->pp_buf, "\n");
 		return 1;
 	} else {
 		put_dev_sector(sect);

In preparation for removing the strlcat API[1], replace the char *pp_buf with a struct seq_buf, which tracks the current write position and remaining space internally. This allows for:

- Direct use of seq_buf_printf() in place of snprintf()+strlcat() pairs, eliminating local tmp buffers throughout.
- Adjacent strlcat() calls that build strings piece-by-piece (e.g., strlcat("["); strlcat(name); strlcat("]")) to be collapsed into single seq_buf_printf() calls.
- Simpler call sites: seq_buf_puts() takes only the buffer and string, with no need to pass PAGE_SIZE at every call.

The backing buffer allocation is unchanged (__get_free_page), and the output path uses seq_buf_str() to NUL-terminate before passing to printk().

Link https://github.com/KSPP/linux/issues/370 [1]

Cc Andy Shevchenko <[email protected]>

Cc Josh Law <[email protected]>

Signed-off-by Kees Cook <[email protected]>

---

I couldn't help myself. Here's the full patch, as I suggested in
https://lore.kernel.org/lkml/202603201230.74BBFFABAD@keescook/
There are plenty more like this to do...

block/partitions/acorn.c +1 -1

 	if (rr->magic == RISCIX_MAGIC) {
 		unsigned long size = nr_sects > 2 ? 2 : nr_sects;
 		int part;
 
-		strlcat(state->pp_buf, " <", PAGE_SIZE);
+		seq_buf_puts(&state->pp_buf, " <");
 
 		put_partition(state, slot++, first_sect, size);
 		for (part = 0; part < 8; part++) {

block/partitions/aix.c +0 -1

@@ -173,24 +173,22 @@ int aix_partition(struct parsed_partitions *state)
 	if (d) {
 		struct lvm_rec *p = (struct lvm_rec *)d;
 		u16 lvm_version = be16_to_cpu(p->version);
-		char tmp[64];
 
 		if (lvm_version == 1) {

block/partitions/aix.c +0 -1

 		}
-		strlcat(state->pp_buf, tmp, PAGE_SIZE);
 		put_dev_sector(sect);
 	}
 	if (vgda_sector && (d = read_part_sector(state, vgda_sector, &sect))) {

block/partitions/amiga.c +5 -6

-			char tmp[42];
 
 			__be32 *dt = (__be32 *)dostype;
 			*dt = pb->pb_Environment[16];
 			if (dostype[3] < ' ')
-				snprintf(tmp, sizeof(tmp), " (%c%c%c^%c)",
-					dostype[0], dostype[1],
-					dostype[2], dostype[3] + '@' );
+				seq_buf_printf(&state->pp_buf,
+					       " (%c%c%c^%c)",
+					       dostype[0], dostype[1],
+					       dostype[2],
+					       dostype[3] + '@');
 			else
-				snprintf(tmp, sizeof(tmp), " (%c%c%c%c)",
-					dostype[0], dostype[1],

block/partitions/amiga.c +3 -0

+			seq_buf_printf(&state->pp_buf, "(res %d spb %d)",
+				       be32_to_cpu(pb->pb_Environment[6]),
+				       be32_to_cpu(pb->pb_Environment[4]));
 		}
 		res = 1;

On Fri, Mar 20, 2026 at 05:48:44PM -0700, Kees Cook wrote:

Quoted 16 lines

block/partitions/amiga.c +5 -6

-			char tmp[42];
 
 			__be32 *dt = (__be32 *)dostype;
 			*dt = pb->pb_Environment[16];
 			if (dostype[3] < ' ')
-				snprintf(tmp, sizeof(tmp), " (%c%c%c^%c)",
-					dostype[0], dostype[1],
-					dostype[2], dostype[3] + '@' );
+				seq_buf_printf(&state->pp_buf,
+					       " (%c%c%c^%c)",
+					       dostype[0], dostype[1],
+					       dostype[2],
+					       dostype[3] + '@');
 			else
-				snprintf(tmp, sizeof(tmp), " (%c%c%c%c)",
-					dostype[0], dostype[1],

block/partitions/amiga.c int amiga_partition(struct parsed_partitions *state) · line 190

Quoted 10 lines

block/partitions/amiga.c +4 -6

-					dostype[2], dostype[3]);
-			strlcat(state->pp_buf, tmp, PAGE_SIZE);
-			snprintf(tmp, sizeof(tmp), "(res %d spb %d)",
-				be32_to_cpu(pb->pb_Environment[6]),
-				be32_to_cpu(pb->pb_Environment[4]));
-			strlcat(state->pp_buf, tmp, PAGE_SIZE);
+				seq_buf_printf(&state->pp_buf,
+					       " (%c%c%c%c)",
+					       dostype[0], dostype[1],
+					       dostype[2], dostype[3]);

Wouldn't

				seq_buf_printf(&state->pp_buf, " (%.4s)", dostype);

work?

But probably okay as in the previous branch it needs more work to follow, something like

			char dostype[8];
			...
			if (dostype[3] < ' ') {
				/* Escape control character */
				dostype[4] = dostype[3] + '@';
				dostype[3] = '^';
				seq_buf_printf(&state->pp_buf, " (%.5s)", dostype);
			} else {
				seq_buf_printf(&state->pp_buf, " (%.4s)", dostype);
			}

Taking how invasive is this, it might be better to done separately.

Quoted 3 lines

block/partitions/amiga.c +3 -0

+			seq_buf_printf(&state->pp_buf, "(res %d spb %d)",
+				       be32_to_cpu(pb->pb_Environment[6]),
+				       be32_to_cpu(pb->pb_Environment[4]));

Quoted 12 lines · Kees Cook

In preparation for removing the strlcat API[1], replace the char *pp_buf with a struct seq_buf, which tracks the current write position and remaining space internally. This allows for:

- Direct use of seq_buf_printf() in place of snprintf()+strlcat() pairs, eliminating local tmp buffers throughout.
- Adjacent strlcat() calls that build strings piece-by-piece (e.g., strlcat("["); strlcat(name); strlcat("]")) to be collapsed into single seq_buf_printf() calls.
- Simpler call sites: seq_buf_puts() takes only the buffer and string, with no need to pass PAGE_SIZE at every call.

Quoted 3 lines

The backing buffer allocation is unchanged (__get_free_page), and the output path uses seq_buf_str() to NUL-terminate before passing to printk().

Thanks a lot! A few comments below.
Personally I'm in favour of this patch as it also removes a lot of ugly code (which is scoped string manipulations), FWIW,

Reviewed-by Andy Shevchenko <[email protected]>

Quoted 4 lines

Link https://github.com/KSPP/linux/issues/370 [1]

Cc Andy Shevchenko <[email protected]>

Cc Josh Law <[email protected]>

While not long, this still can be placed...

Quoted 2 lines

Signed-off-by Kees Cook <[email protected]>

---

...somewhere here to reduce unneeded noise in the commit message.

Quoted 3 lines

I couldn't help myself. Here's the full patch, as I suggested in
https://lore.kernel.org/lkml/202603201230.74BBFFABAD@keescook/
There are plenty more like this to do...

Indeed, but thanks for the example on how to do that!

But probably okay as in the previous branch it needs more work to follow, something like

			char dostype[8];
			...
			if (dostype[3] < ' ') {
				/* Escape control character */
				dostype[4] = dostype[3] + '@';
				dostype[3] = '^';
				seq_buf_printf(&state->pp_buf, " (%.5s)", dostype);

			} else {
				seq_buf_printf(&state->pp_buf, " (%.4s)", dostype);
			}

Taking how invasive is this, it might be better to done separately.

Quoted 5 lines

block/partitions/amiga.c +3 -0

+			seq_buf_printf(&state->pp_buf, "(res %d spb %d)",
+				       be32_to_cpu(pb->pb_Environment[6]),
+				       be32_to_cpu(pb->pb_Environment[4]));
 		}
 		res = 1;  

Quoted 40 lines · On Mon, 23 Mar 2026 10:51:44 +0200 Andy Shevchenko…

Quoted 12 lines · Kees Cook

In preparation for removing the strlcat API[1], replace the char *pp_buf with a struct seq_buf, which tracks the current write position and remaining space internally. This allows for:

- Direct use of seq_buf_printf() in place of snprintf()+strlcat() pairs, eliminating local tmp buffers throughout.
- Adjacent strlcat() calls that build strings piece-by-piece (e.g., strlcat("["); strlcat(name); strlcat("]")) to be collapsed into single seq_buf_printf() calls.
- Simpler call sites: seq_buf_puts() takes only the buffer and string, with no need to pass PAGE_SIZE at every call.

Quoted 3 lines

The backing buffer allocation is unchanged (__get_free_page), and the output path uses seq_buf_str() to NUL-terminate before passing to printk().

Thanks a lot! A few comments below.
Personally I'm in favour of this patch as it also removes a lot of ugly code (which is scoped string manipulations), FWIW,

Reviewed-by Andy Shevchenko <[email protected]>

Quoted 4 lines

Link https://github.com/KSPP/linux/issues/370 [1]

Cc Andy Shevchenko <[email protected]>

Cc Josh Law <[email protected]>

While not long, this still can be placed...

Quoted 2 lines

Signed-off-by Kees Cook <[email protected]>

---

...somewhere here to reduce unneeded noise in the commit message.

Quoted 3 lines

I couldn't help myself. Here's the full patch, as I suggested in
https://lore.kernel.org/lkml/202603201230.74BBFFABAD@keescook/
There are plenty more like this to do...

Indeed, but thanks for the example on how to do that!

...

Quoted 10 lines

But probably okay as in the previous branch it needs more work to follow, something like

			char dostype[8];
			...
			if (dostype[3] < ' ') {
				/* Escape control character */
				dostype[4] = dostype[3] + '@';
				dostype[3] = '^';
				seq_buf_printf(&state->pp_buf, " (%.5s)", dostype);

Or just:

				seq_buf_printf(&state->pp_buf, " (%.3s^%c)", dostype, dostype[3] + '@');

	David

Quoted 5 lines

			} else {
				seq_buf_printf(&state->pp_buf, " (%.4s)", dostype);
			}

Taking how invasive is this, it might be better to done separately.