f2fs: revert summary entry count from 2048 to 512 in 16kb block support

The recent increase in the number of Segment Summary Area (SSA) entries
from 512 to 2048 was an unintentional change in logic of 16kb block
support. This commit corrects the issue.

To better utilize the space available from the erroneous 2048-entry
calculation, we are implementing a solution to share the currently
unused SSA space with neighboring segments. This enhances overall
SSA utilization without impacting the established 8MB segment size.

Fixes: d7e9a90 ("f2fs: Support Block Size == Page Size")
Signed-off-by: Daeho Jeong <daehojeong@google.com>
Reviewed-by: Chao Yu <chao@kernel.org>
Signed-off-by: Jaegeuk Kim <jaegeuk@kernel.org>

Author: Daeho Jeong

fs/f2fs/f2fs.h

@@ -245,6 +245,7 @@ struct f2fs_mount_info {
 #define F2FS_FEATURE_COMPRESSION		0x00002000
 #define F2FS_FEATURE_RO				0x00004000
 #define F2FS_FEATURE_DEVICE_ALIAS		0x00008000
+#define F2FS_FEATURE_PACKED_SSA			0x00010000
 
 #define __F2FS_HAS_FEATURE(raw_super, mask)				\
 	((raw_super->feature & cpu_to_le32(mask)) != 0)
@@ -4704,6 +4705,7 @@ F2FS_FEATURE_FUNCS(casefold, CASEFOLD);
 F2FS_FEATURE_FUNCS(compression, COMPRESSION);
 F2FS_FEATURE_FUNCS(readonly, RO);
 F2FS_FEATURE_FUNCS(device_alias, DEVICE_ALIAS);
+F2FS_FEATURE_FUNCS(packed_ssa, PACKED_SSA);
 
 #ifdef CONFIG_BLK_DEV_ZONED
 static inline bool f2fs_zone_is_seq(struct f2fs_sb_info *sbi, int devi,

fs/f2fs/gc.c

@@ -1735,7 +1735,7 @@ static int do_garbage_collect(struct f2fs_sb_info *sbi,
 	unsigned char type = IS_DATASEG(get_seg_entry(sbi, segno)->type) ?
 						SUM_TYPE_DATA : SUM_TYPE_NODE;
 	unsigned char data_type = (type == SUM_TYPE_DATA) ? DATA : NODE;
-	int submitted = 0;
+	int submitted = 0, sum_blk_cnt;
 
 	if (__is_large_section(sbi)) {
 		sec_end_segno = rounddown(end_segno, SEGS_PER_SEC(sbi));
@@ -1769,22 +1769,28 @@ static int do_garbage_collect(struct f2fs_sb_info *sbi,
 
 	sanity_check_seg_type(sbi, get_seg_entry(sbi, segno)->type);
 
+	segno = rounddown(segno, SUMS_PER_BLOCK);
+	sum_blk_cnt = DIV_ROUND_UP(end_segno - segno, SUMS_PER_BLOCK);
 	/* readahead multi ssa blocks those have contiguous address */
 	if (__is_large_section(sbi))
 		f2fs_ra_meta_pages(sbi, GET_SUM_BLOCK(sbi, segno),
-					end_segno - segno, META_SSA, true);
+					sum_blk_cnt, META_SSA, true);
 
 	/* reference all summary page */
 	while (segno < end_segno) {
-		struct folio *sum_folio = f2fs_get_sum_folio(sbi, segno++);
+		struct folio *sum_folio = f2fs_get_sum_folio(sbi, segno);
+
+		segno += SUMS_PER_BLOCK;
 		if (IS_ERR(sum_folio)) {
 			int err = PTR_ERR(sum_folio);
 
-			end_segno = segno - 1;
-			for (segno = start_segno; segno < end_segno; segno++) {
+			end_segno = segno - SUMS_PER_BLOCK;
+			segno = rounddown(start_segno, SUMS_PER_BLOCK);
+			while (segno < end_segno) {
 				sum_folio = filemap_get_folio(META_MAPPING(sbi),
 						GET_SUM_BLOCK(sbi, segno));
 				folio_put_refs(sum_folio, 2);
+				segno += SUMS_PER_BLOCK;
 			}
 			return err;
 		}
@@ -1793,68 +1799,83 @@ static int do_garbage_collect(struct f2fs_sb_info *sbi,
 
 	blk_start_plug(&plug);
 
-	for (segno = start_segno; segno < end_segno; segno++) {
-		struct f2fs_summary_block *sum;
+	segno = start_segno;
+	while (segno < end_segno) {
+		unsigned int cur_segno;
 
 		/* find segment summary of victim */
 		struct folio *sum_folio = filemap_get_folio(META_MAPPING(sbi),
 					GET_SUM_BLOCK(sbi, segno));
+		unsigned int block_end_segno = rounddown(segno, SUMS_PER_BLOCK)
+					+ SUMS_PER_BLOCK;
+
+		if (block_end_segno > end_segno)
+			block_end_segno = end_segno;
 
 		if (is_cursec(sbi, GET_SEC_FROM_SEG(sbi, segno))) {
 			f2fs_err(sbi, "%s: segment %u is used by log",
 							__func__, segno);
 			f2fs_bug_on(sbi, 1);
-			goto skip;
+			goto next_block;
 		}
 
-		if (get_valid_blocks(sbi, segno, false) == 0)
-			goto freed;
-		if (gc_type == BG_GC && __is_large_section(sbi) &&
-				migrated >= sbi->migration_granularity)
-			goto skip;
 		if (!folio_test_uptodate(sum_folio) ||
 		    unlikely(f2fs_cp_error(sbi)))
-			goto skip;
+			goto next_block;
 
-		sum = folio_address(sum_folio);
-		if (type != GET_SUM_TYPE((&sum->footer))) {
-			f2fs_err(sbi, "Inconsistent segment (%u) type [%d, %d] in SIT and SSA",
-				 segno, type, GET_SUM_TYPE((&sum->footer)));
-			f2fs_stop_checkpoint(sbi, false,
-				STOP_CP_REASON_CORRUPTED_SUMMARY);
-			goto skip;
-		}
+		for (cur_segno = segno; cur_segno < block_end_segno;
+				cur_segno++) {
+			struct f2fs_summary_block *sum;
 
-		/*
-		 * this is to avoid deadlock:
-		 * - lock_page(sum_page)         - f2fs_replace_block
-		 *  - check_valid_map()            - down_write(sentry_lock)
-		 *   - down_read(sentry_lock)     - change_curseg()
-		 *                                  - lock_page(sum_page)
-		 */
-		if (type == SUM_TYPE_NODE)
-			submitted += gc_node_segment(sbi, sum->entries, segno,
-								gc_type);
-		else
-			submitted += gc_data_segment(sbi, sum->entries, gc_list,
-							segno, gc_type,
-							force_migrate);
+			if (get_valid_blocks(sbi, cur_segno, false) == 0)
+				goto freed;
+			if (gc_type == BG_GC && __is_large_section(sbi) &&
+					migrated >= sbi->migration_granularity)
+				continue;
 
-		stat_inc_gc_seg_count(sbi, data_type, gc_type);
-		sbi->gc_reclaimed_segs[sbi->gc_mode]++;
-		migrated++;
+			sum = SUM_BLK_PAGE_ADDR(sum_folio, cur_segno);
+			if (type != GET_SUM_TYPE((&sum->footer))) {
+				f2fs_err(sbi, "Inconsistent segment (%u) type "
+						"[%d, %d] in SSA and SIT",
+						cur_segno, type,
+						GET_SUM_TYPE((&sum->footer)));
+				f2fs_stop_checkpoint(sbi, false,
+						STOP_CP_REASON_CORRUPTED_SUMMARY);
+				continue;
+			}
 
-freed:
-		if (gc_type == FG_GC &&
-				get_valid_blocks(sbi, segno, false) == 0)
-			seg_freed++;
+			/*
+			 * this is to avoid deadlock:
+			 *  - lock_page(sum_page)     - f2fs_replace_block
+			 *   - check_valid_map()        - down_write(sentry_lock)
+			 *    - down_read(sentry_lock) - change_curseg()
+			 *                               - lock_page(sum_page)
+			 */
+			if (type == SUM_TYPE_NODE)
+				submitted += gc_node_segment(sbi, sum->entries,
+						cur_segno, gc_type);
+			else
+				submitted += gc_data_segment(sbi, sum->entries,
+						gc_list, cur_segno,
+						gc_type, force_migrate);
 
-		if (__is_large_section(sbi))
-			sbi->next_victim_seg[gc_type] =
-				(segno + 1 < sec_end_segno) ?
-					segno + 1 : NULL_SEGNO;
-skip:
+			stat_inc_gc_seg_count(sbi, data_type, gc_type);
+			sbi->gc_reclaimed_segs[sbi->gc_mode]++;
+			migrated++;
+
+freed:
+			if (gc_type == FG_GC &&
+					get_valid_blocks(sbi, cur_segno, false) == 0)
+				seg_freed++;
+
+			if (__is_large_section(sbi))
+				sbi->next_victim_seg[gc_type] =
+					(cur_segno + 1 < sec_end_segno) ?
+					cur_segno + 1 : NULL_SEGNO;
+		}
+next_block:
 		folio_put_refs(sum_folio, 2);
+		segno = block_end_segno;
 	}
 
 	if (submitted)

fs/f2fs/recovery.c

@@ -522,7 +522,7 @@ static int check_index_in_prev_nodes(struct f2fs_sb_info *sbi,
 	sum_folio = f2fs_get_sum_folio(sbi, segno);
 	if (IS_ERR(sum_folio))
 		return PTR_ERR(sum_folio);
-	sum_node = folio_address(sum_folio);
+	sum_node = SUM_BLK_PAGE_ADDR(sum_folio, segno);
 	sum = sum_node->entries[blkoff];
 	f2fs_folio_put(sum_folio, true);
 got_it:

fs/f2fs/segment.c

@@ -2712,17 +2712,37 @@ struct folio *f2fs_get_sum_folio(struct f2fs_sb_info *sbi, unsigned int segno)
 void f2fs_update_meta_page(struct f2fs_sb_info *sbi,
 					void *src, block_t blk_addr)
 {
-	struct folio *folio = f2fs_grab_meta_folio(sbi, blk_addr);
+	struct folio *folio;
+
+	if (SUMS_PER_BLOCK == 1)
+		folio = f2fs_grab_meta_folio(sbi, blk_addr);
+	else
+		folio = f2fs_get_meta_folio_retry(sbi, blk_addr);
+
+	if (IS_ERR(folio))
+		return;
 
 	memcpy(folio_address(folio), src, PAGE_SIZE);
 	folio_mark_dirty(folio);
 	f2fs_folio_put(folio, true);
 }
 
 static void write_sum_page(struct f2fs_sb_info *sbi,
-			struct f2fs_summary_block *sum_blk, block_t blk_addr)
+		struct f2fs_summary_block *sum_blk, unsigned int segno)
 {
-	f2fs_update_meta_page(sbi, (void *)sum_blk, blk_addr);
+	struct folio *folio;
+
+	if (SUMS_PER_BLOCK == 1)
+		return f2fs_update_meta_page(sbi, (void *)sum_blk,
+				GET_SUM_BLOCK(sbi, segno));
+
+	folio = f2fs_get_sum_folio(sbi, segno);
+	if (IS_ERR(folio))
+		return;
+
+	memcpy(SUM_BLK_PAGE_ADDR(folio, segno), sum_blk, sizeof(*sum_blk));
+	folio_mark_dirty(folio);
+	f2fs_folio_put(folio, true);
 }
 
 static void write_current_sum_page(struct f2fs_sb_info *sbi,
@@ -2987,7 +3007,7 @@ static int new_curseg(struct f2fs_sb_info *sbi, int type, bool new_sec)
 	int ret;
 
 	if (curseg->inited)
-		write_sum_page(sbi, curseg->sum_blk, GET_SUM_BLOCK(sbi, segno));
+		write_sum_page(sbi, curseg->sum_blk, segno);
 
 	segno = __get_next_segno(sbi, type);
 	ret = get_new_segment(sbi, &segno, new_sec, pinning);
@@ -3046,7 +3066,7 @@ static int change_curseg(struct f2fs_sb_info *sbi, int type)
 	struct folio *sum_folio;
 
 	if (curseg->inited)
-		write_sum_page(sbi, curseg->sum_blk, GET_SUM_BLOCK(sbi, curseg->segno));
+		write_sum_page(sbi, curseg->sum_blk, curseg->segno);
 
 	__set_test_and_inuse(sbi, new_segno);
 
@@ -3065,7 +3085,7 @@ static int change_curseg(struct f2fs_sb_info *sbi, int type)
 		memset(curseg->sum_blk, 0, SUM_ENTRY_SIZE);
 		return PTR_ERR(sum_folio);
 	}
-	sum_node = folio_address(sum_folio);
+	sum_node = SUM_BLK_PAGE_ADDR(sum_folio, new_segno);
 	memcpy(curseg->sum_blk, sum_node, SUM_ENTRY_SIZE);
 	f2fs_folio_put(sum_folio, true);
 	return 0;
@@ -3154,8 +3174,7 @@ static void __f2fs_save_inmem_curseg(struct f2fs_sb_info *sbi, int type)
 		goto out;
 
 	if (get_valid_blocks(sbi, curseg->segno, false)) {
-		write_sum_page(sbi, curseg->sum_blk,
-				GET_SUM_BLOCK(sbi, curseg->segno));
+		write_sum_page(sbi, curseg->sum_blk, curseg->segno);
 	} else {
 		mutex_lock(&DIRTY_I(sbi)->seglist_lock);
 		__set_test_and_free(sbi, curseg->segno, true);
@@ -3833,8 +3852,7 @@ int f2fs_allocate_data_block(struct f2fs_sb_info *sbi, struct folio *folio,
 	if (segment_full) {
 		if (type == CURSEG_COLD_DATA_PINNED &&
 		    !((curseg->segno + 1) % sbi->segs_per_sec)) {
-			write_sum_page(sbi, curseg->sum_blk,
-					GET_SUM_BLOCK(sbi, curseg->segno));
+			write_sum_page(sbi, curseg->sum_blk, curseg->segno);
 			reset_curseg_fields(curseg);
 			goto skip_new_segment;
 		}

fs/f2fs/segment.h

@@ -85,8 +85,12 @@ static inline void sanity_check_seg_type(struct f2fs_sb_info *sbi,
 #define GET_ZONE_FROM_SEG(sbi, segno)				\
 	GET_ZONE_FROM_SEC(sbi, GET_SEC_FROM_SEG(sbi, segno))
 
-#define GET_SUM_BLOCK(sbi, segno)				\
-	((sbi)->sm_info->ssa_blkaddr + (segno))
+#define SUMS_PER_BLOCK (F2FS_BLKSIZE / F2FS_SUM_BLKSIZE)
+#define GET_SUM_BLOCK(sbi, segno)	\
+	(SM_I(sbi)->ssa_blkaddr + (segno / SUMS_PER_BLOCK))
+#define GET_SUM_BLKOFF(segno) (segno % SUMS_PER_BLOCK)
+#define SUM_BLK_PAGE_ADDR(folio, segno)	\
+	(folio_address(folio) + GET_SUM_BLKOFF(segno) * F2FS_SUM_BLKSIZE)
 
 #define GET_SUM_TYPE(footer) ((footer)->entry_type)
 #define SET_SUM_TYPE(footer, type) ((footer)->entry_type = (type))

fs/f2fs/super.c

@@ -4080,6 +4080,20 @@ static int sanity_check_raw_super(struct f2fs_sb_info *sbi,
 	if (sanity_check_area_boundary(sbi, folio, index))
 		return -EFSCORRUPTED;
 
+	/*
+	 * Check for legacy summary layout on 16KB+ block devices.
+	 * Modern f2fs-tools packs multiple 4KB summary areas into one block,
+	 * whereas legacy versions used one block per summary, leading
+	 * to a much larger SSA.
+	 */
+	if (SUMS_PER_BLOCK > 1 &&
+		    !(__F2FS_HAS_FEATURE(raw_super, F2FS_FEATURE_PACKED_SSA))) {
+		f2fs_info(sbi, "Error: Device formatted with a legacy version. "
+			"Please reformat with a tool supporting the packed ssa "
+			"feature for block sizes larger than 4kb.");
+		return -EOPNOTSUPP;
+	}
+
 	return 0;
 }
 

fs/f2fs/sysfs.c

@@ -235,6 +235,9 @@ static ssize_t features_show(struct f2fs_attr *a,
 	if (f2fs_sb_has_compression(sbi))
 		len += sysfs_emit_at(buf, len, "%s%s",
 				len ? ", " : "", "compression");
+	if (f2fs_sb_has_packed_ssa(sbi))
+		len += sysfs_emit_at(buf, len, "%s%s",
+				len ? ", " : "", "packed_ssa");
 	len += sysfs_emit_at(buf, len, "%s%s",
 				len ? ", " : "", "pin_file");
 	len += sysfs_emit_at(buf, len, "\n");
@@ -1296,6 +1299,7 @@ F2FS_FEATURE_RO_ATTR(pin_file);
 #ifdef CONFIG_UNICODE
 F2FS_FEATURE_RO_ATTR(linear_lookup);
 #endif
+F2FS_FEATURE_RO_ATTR(packed_ssa);
 
 #define ATTR_LIST(name) (&f2fs_attr_##name.attr)
 static struct attribute *f2fs_attrs[] = {
@@ -1455,6 +1459,7 @@ static struct attribute *f2fs_feat_attrs[] = {
 #ifdef CONFIG_UNICODE
 	BASE_ATTR_LIST(linear_lookup),
 #endif
+	BASE_ATTR_LIST(packed_ssa),
 	NULL,
 };
 ATTRIBUTE_GROUPS(f2fs_feat);
@@ -1490,6 +1495,7 @@ F2FS_SB_FEATURE_RO_ATTR(casefold, CASEFOLD);
 F2FS_SB_FEATURE_RO_ATTR(compression, COMPRESSION);
 F2FS_SB_FEATURE_RO_ATTR(readonly, RO);
 F2FS_SB_FEATURE_RO_ATTR(device_alias, DEVICE_ALIAS);
+F2FS_SB_FEATURE_RO_ATTR(packed_ssa, PACKED_SSA);
 
 static struct attribute *f2fs_sb_feat_attrs[] = {
 	ATTR_LIST(sb_encryption),
@@ -1507,6 +1513,7 @@ static struct attribute *f2fs_sb_feat_attrs[] = {
 	ATTR_LIST(sb_compression),
 	ATTR_LIST(sb_readonly),
 	ATTR_LIST(sb_device_alias),
+	ATTR_LIST(sb_packed_ssa),
 	NULL,
 };
 ATTRIBUTE_GROUPS(f2fs_sb_feat);

include/linux/f2fs_fs.h

@@ -17,6 +17,7 @@
 #define F2FS_LOG_SECTORS_PER_BLOCK	(PAGE_SHIFT - 9) /* log number for sector/blk */
 #define F2FS_BLKSIZE			PAGE_SIZE /* support only block == page */
 #define F2FS_BLKSIZE_BITS		PAGE_SHIFT /* bits for F2FS_BLKSIZE */
+#define F2FS_SUM_BLKSIZE		4096	/* only support 4096 byte sum block */
 #define F2FS_MAX_EXTENSION		64	/* # of extension entries */
 #define F2FS_EXTENSION_LEN		8	/* max size of extension */
 
@@ -441,7 +442,7 @@ struct f2fs_sit_block {
  * from node's page's beginning to get a data block address.
  * ex) data_blkaddr = (block_t)(nodepage_start_address + ofs_in_node)
  */
-#define ENTRIES_IN_SUM		(F2FS_BLKSIZE / 8)
+#define ENTRIES_IN_SUM		(F2FS_SUM_BLKSIZE / 8)
 #define	SUMMARY_SIZE		(7)	/* sizeof(struct f2fs_summary) */
 #define	SUM_FOOTER_SIZE		(5)	/* sizeof(struct summary_footer) */
 #define SUM_ENTRY_SIZE		(SUMMARY_SIZE * ENTRIES_IN_SUM)
@@ -467,7 +468,7 @@ struct summary_footer {
 	__le32 check_sum;		/* summary checksum */
 } __packed;
 
-#define SUM_JOURNAL_SIZE	(F2FS_BLKSIZE - SUM_FOOTER_SIZE -\
+#define SUM_JOURNAL_SIZE	(F2FS_SUM_BLKSIZE - SUM_FOOTER_SIZE -\
 				SUM_ENTRY_SIZE)
 #define NAT_JOURNAL_ENTRIES	((SUM_JOURNAL_SIZE - 2) /\
 				sizeof(struct nat_journal_entry))