fsck: Check write pointer consistency of non-open zones

To catch bugs in write pointer handling code for zoned block devices,
have fsck check consistency of write pointers of non-open zones, that
current segments do not point to. Check two items comparing write pointer
positions with valid block maps in SIT.

The first item is check for zones with no valid blocks. When there is no
valid blocks in a zone, the write pointer should be at the start of the
zone. If not, next write operation to the zone will cause unaligned write
error. If write pointer is not at the zone start, reset the zone to move
the write pointer to the zone start.

The second item is check between write pointer position and the last
valid block in the zone. It is unexpected that the last valid block
position is beyond the write pointer. In such a case, report as the bug.
Fix is not required for such zone, because the zone is not selected for
next write operation until the zone get discarded.

In the same manner as the consistency check for current segments, do the
check and fix twice: at the beginning of do_fsck() to avoid unaligned
write error during fsck, and at fsck_verify() to reflect meta data
updates by fsck.

Signed-off-by: Shin'ichiro Kawasaki <shinichiro.kawasaki@wdc.com>
Reviewed-by: Chao Yu <yuchao0@huawei.com>
Signed-off-by: Jaegeuk Kim <jaegeuk@kernel.org>

fsck/fsck.c

@@ -2756,6 +2756,122 @@ out:
 	return cnt;
 }
 
+#ifdef HAVE_LINUX_BLKZONED_H
+
+struct write_pointer_check_data {
+	struct f2fs_sb_info *sbi;
+	int dev_index;
+};
+
+static int chk_and_fix_wp_with_sit(int i, void *blkzone, void *opaque)
+{
+	struct blk_zone *blkz = (struct blk_zone *)blkzone;
+	struct write_pointer_check_data *wpd = opaque;
+	struct f2fs_sb_info *sbi = wpd->sbi;
+	struct device_info *dev = c.devices + wpd->dev_index;
+	struct f2fs_fsck *fsck = F2FS_FSCK(sbi);
+	block_t zone_block, wp_block, wp_blkoff;
+	unsigned int zone_segno, wp_segno;
+	struct curseg_info *cs;
+	int cs_index, ret, last_valid_blkoff;
+	int log_sectors_per_block = sbi->log_blocksize - SECTOR_SHIFT;
+	unsigned int segs_per_zone = sbi->segs_per_sec * sbi->secs_per_zone;
+
+	if (blk_zone_conv(blkz))
+		return 0;
+
+	zone_block = dev->start_blkaddr
+		+ (blk_zone_sector(blkz) >> log_sectors_per_block);
+	zone_segno = GET_SEGNO(sbi, zone_block);
+	if (zone_segno >= MAIN_SEGS(sbi))
+		return 0;
+
+	wp_block = dev->start_blkaddr
+		+ (blk_zone_wp_sector(blkz) >> log_sectors_per_block);
+	wp_segno = GET_SEGNO(sbi, wp_block);
+	wp_blkoff = wp_block - START_BLOCK(sbi, wp_segno);
+
+	/* if a curseg points to the zone, skip the check */
+	for (cs_index = 0; cs_index < NO_CHECK_TYPE; cs_index++) {
+		cs = &SM_I(sbi)->curseg_array[cs_index];
+		if (zone_segno <= cs->segno &&
+		    cs->segno < zone_segno + segs_per_zone)
+			return 0;
+	}
+
+	last_valid_blkoff = last_vblk_off_in_zone(sbi, zone_segno);
+
+	/*
+	 * When there is no valid block in the zone, check write pointer is
+	 * at zone start. If not, reset the write pointer.
+	 */
+	if (last_valid_blkoff < 0 &&
+	    blk_zone_wp_sector(blkz) != blk_zone_sector(blkz)) {
+		if (!c.fix_on) {
+			MSG(0, "Inconsistent write pointer: wp[0x%x,0x%x]\n",
+			    wp_segno, wp_blkoff);
+			fsck->chk.wp_inconsistent_zones++;
+			return 0;
+		}
+
+		FIX_MSG("Reset write pointer of zone at segment 0x%x",
+			zone_segno);
+		ret = f2fs_reset_zone(wpd->dev_index, blkz);
+		if (ret) {
+			printf("[FSCK] Write pointer reset failed: %s\n",
+			       dev->path);
+			return ret;
+		}
+		fsck->chk.wp_fixed = 1;
+		return 0;
+	}
+
+	/*
+	 * If valid blocks exist in the zone beyond the write pointer, it
+	 * is a bug. No need to fix because the zone is not selected for the
+	 * write. Just report it.
+	 */
+	if (last_valid_blkoff + zone_block > wp_block) {
+		MSG(0, "Unexpected invalid write pointer: wp[0x%x,0x%x]\n",
+		    wp_segno, wp_blkoff);
+		return 0;
+	}
+
+	return 0;
+}
+
+static void fix_wp_sit_alignment(struct f2fs_sb_info *sbi)
+{
+	unsigned int i;
+	struct write_pointer_check_data wpd = {	sbi, 0 };
+
+	if (c.zoned_model != F2FS_ZONED_HM)
+		return;
+
+	for (i = 0; i < MAX_DEVICES; i++) {
+		if (!c.devices[i].path)
+			break;
+		if (c.devices[i].zoned_model != F2FS_ZONED_HM)
+			break;
+
+		wpd.dev_index = i;
+		if (f2fs_report_zones(i, chk_and_fix_wp_with_sit, &wpd)) {
+			printf("[FSCK] Write pointer check failed: %s\n",
+			       c.devices[i].path);
+			return;
+		}
+	}
+}
+
+#else
+
+static void fix_wp_sit_alignment(struct f2fs_sb_info *sbi)
+{
+	return;
+}
+
+#endif
+
 /*
  * Check and fix consistency with write pointers at the beginning of
  * fsck so that following writes by fsck do not fail.
@@ -2771,6 +2887,8 @@ void fsck_chk_and_fix_write_pointers(struct f2fs_sb_info *sbi)
 		fix_curseg_info(sbi);
 		fsck->chk.wp_fixed = 1;
 	}
+
+	fix_wp_sit_alignment(sbi);
 }
 
 int fsck_chk_curseg_info(struct f2fs_sb_info *sbi)
@@ -2989,6 +3107,7 @@ int fsck_verify(struct f2fs_sb_info *sbi)
 			fix_hard_links(sbi);
 			fix_nat_entries(sbi);
 			rewrite_sit_area_bitmap(sbi);
+			fix_wp_sit_alignment(sbi);
 			fix_curseg_info(sbi);
 			fix_checksum(sbi);
 			fix_checkpoints(sbi);