On Dec 09, 2019 / 10:04, Chao Yu wrote:
> On 2019/12/2 17:40, Shin'ichiro Kawasaki wrote:
> > To catch f2fs bugs in write pointer handling code for zoned block
> > devices, check write pointers of non-open zones that current segments do
> > not point to. Do this check at mount time, after the fsync data recovery
> > and current segments' write pointer consistency fix. Or when fsync data
> > recovery is disabled by mount option, do the check when there is no fsync
> > data.
> >
> > Check two items comparing write pointers 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 write pointer
> > to place at the zone start.
> >
> > The second item is check between the 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 a bug.
> > Fix is not required for such zone, because the zone is not selected for
> > next write operation until the zone get discarded.
> >
> > Signed-off-by: Shin'ichiro Kawasaki <[email protected]>
> > ---
> > fs/f2fs/f2fs.h | 1 +
> > fs/f2fs/segment.c | 126 ++++++++++++++++++++++++++++++++++++++++++++++
> > fs/f2fs/super.c | 11 ++++
> > 3 files changed, 138 insertions(+)
> >
> > diff --git a/fs/f2fs/f2fs.h b/fs/f2fs/f2fs.h
> > index 002c417b0a53..23a84d7f17b8 100644
> > --- a/fs/f2fs/f2fs.h
> > +++ b/fs/f2fs/f2fs.h
> > @@ -3156,6 +3156,7 @@ int f2fs_lookup_journal_in_cursum(struct f2fs_journal
> > *journal, int type,
> > unsigned int val, int alloc);
> > void f2fs_flush_sit_entries(struct f2fs_sb_info *sbi, struct cp_control
> > *cpc);
> > int f2fs_fix_curseg_write_pointer(struct f2fs_sb_info *sbi);
> > +int f2fs_check_write_pointer(struct f2fs_sb_info *sbi);
> > int f2fs_build_segment_manager(struct f2fs_sb_info *sbi);
> > void f2fs_destroy_segment_manager(struct f2fs_sb_info *sbi);
> > int __init f2fs_create_segment_manager_caches(void);
> > diff --git a/fs/f2fs/segment.c b/fs/f2fs/segment.c
> > index 9b6c7ab67b93..48903b7a9d25 100644
> > --- a/fs/f2fs/segment.c
> > +++ b/fs/f2fs/segment.c
> > @@ -4370,6 +4370,90 @@ static int sanity_check_curseg(struct f2fs_sb_info
> > *sbi)
> >
> > #ifdef CONFIG_BLK_DEV_ZONED
> >
> > +static int check_zone_write_pointer(struct f2fs_sb_info *sbi,
> > + struct f2fs_dev_info *fdev,
> > + struct blk_zone *zone)
> > +{
> > + unsigned int wp_segno, wp_blkoff, zone_secno, zone_segno, segno;
> > + block_t zone_block, wp_block, last_valid_block;
> > + unsigned int log_sectors_per_block = sbi->log_blocksize - SECTOR_SHIFT;
> > + int i, s, b, ret;
> > + struct seg_entry *se;
> > +
> > + if (zone->type != BLK_ZONE_TYPE_SEQWRITE_REQ)
> > + return 0;
> > +
> > + wp_block = fdev->start_blk + (zone->wp >> log_sectors_per_block);
> > + wp_segno = GET_SEGNO(sbi, wp_block);
> > + wp_blkoff = wp_block - START_BLOCK(sbi, wp_segno);
> > + zone_block = fdev->start_blk + (zone->start >> log_sectors_per_block);
> > + zone_segno = GET_SEGNO(sbi, zone_block);
> > + zone_secno = GET_SEC_FROM_SEG(sbi, zone_segno);
> > +
> > + if (zone_segno >= MAIN_SEGS(sbi))
> > + return 0;
> > +
> > + /*
> > + * Skip check of zones cursegs point to, since
> > + * fix_curseg_write_pointer() checks them.
> > + */
> > + for (i = 0; i < NO_CHECK_TYPE; i++)
> > + if (zone_secno == GET_SEC_FROM_SEG(sbi,
> > + CURSEG_I(sbi, i)->segno))
> > + return 0;
> > +
> > + /*
> > + * Get last valid block of the zone.
> > + */
> > + last_valid_block = zone_block - 1;
> > + for (s = sbi->segs_per_sec - 1; s >= 0; s--) {
> > + segno = zone_segno + s;
> > + se = get_seg_entry(sbi, segno);
> > + for (b = sbi->blocks_per_seg - 1; b >= 0; b--)
> > + if (f2fs_test_bit(b, se->cur_valid_map)) {
> > + last_valid_block = START_BLOCK(sbi, segno) + b;
> > + break;
> > + }
> > + if (last_valid_block >= zone_block)
> > + break;
> > + }
> > +
> > + /*
> > + * If last valid block is beyond the write pointer, report the
> > + * inconsistency. This inconsistency does not cause write error
> > + * because the zone will not be selected for write operation until
> > + * it get discarded. Just report it.
> > + */
> > + if (last_valid_block >= wp_block) {
> > + f2fs_notice(sbi, "Valid block beyond write pointer: "
> > + "valid block[0x%x,0x%x] wp[0x%x,0x%x]",
> > + GET_SEGNO(sbi, last_valid_block),
> > + GET_BLKOFF_FROM_SEG0(sbi, last_valid_block),
> > + wp_segno, wp_blkoff);
> > + return 0;
> > + }
> > +
> > + /*
> > + * If there is no valid block in the zone and if write pointer is
> > + * not at zone start, reset the write pointer.
> > + */
> > + if (last_valid_block + 1 == zone_block && zone->wp != zone->start) {
> > + f2fs_notice(sbi,
> > + "Zone without valid block has non-zero write "
> > + "pointer. Reset the write pointer: wp[0x%x,0x%x]",
> > + wp_segno, wp_blkoff);
> > + ret = blkdev_zone_mgmt(fdev->bdev, REQ_OP_ZONE_RESET,
> > + zone->start, zone->len, GFP_NOFS);
>
> Should use __f2fs_issue_discard_zone() to cover multi-device support?
Yes, __f2fs_issue_discard_zone() for each device adds more check and I think
it is safer for multi-device case. Will re-post the patch with you suggest.
>
> > + if (ret) {
> > + f2fs_notice(sbi, "Reset zone failed: %s (errno=%d)",
> > + fdev->path, ret);
> > + return ret;
> > + }
>
> Just out of curiosity, how long will RESET command take normally?
Though I don't have accurate numbers, it takes around 10 milliseconds to
complete one RESET command for one zone with my system. Assuming the number
of zones to discard here is small, I think the additional overhead is small
enough to ignore.
Thanks!
>
> Thanks,
>
> > + }
> > +
> > + return 0;
> > +}
> > +
> > static struct f2fs_dev_info *get_target_zoned_dev(struct f2fs_sb_info *sbi,
> > block_t zone_blkaddr)
> > {
> > @@ -4442,6 +4526,10 @@ static int fix_curseg_write_pointer(struct
> > f2fs_sb_info *sbi, int type)
> > "curseg[0x%x,0x%x]", type, cs->segno, cs->next_blkoff);
> > allocate_segment_by_default(sbi, type, true);
> >
> > + /* check consistency of the zone curseg pointed to */
> > + if (check_zone_write_pointer(sbi, zbd, &zone))
> > + return -EIO;
> > +
> > /* check newly assigned zone */
> > cs_section = GET_SEC_FROM_SEG(sbi, cs->segno);
> > cs_zone_block = START_BLOCK(sbi, GET_SEG_FROM_SEC(sbi, cs_section));
> > @@ -4492,11 +4580,49 @@ int f2fs_fix_curseg_write_pointer(struct
> > f2fs_sb_info *sbi)
> >
> > return 0;
> > }
> > +
> > +struct check_zone_write_pointer_args {
> > + struct f2fs_sb_info *sbi;
> > + struct f2fs_dev_info *fdev;
> > +};
> > +
> > +static int check_zone_write_pointer_cb(struct blk_zone *zone, unsigned int
> > idx,
> > + void *data) {
> > + struct check_zone_write_pointer_args *args;
> > + args = (struct check_zone_write_pointer_args *)data;
> > +
> > + return check_zone_write_pointer(args->sbi, args->fdev, zone);
> > +}
> > +
> > +int f2fs_check_write_pointer(struct f2fs_sb_info *sbi)
> > +{
> > + int i, ret;
> > + struct check_zone_write_pointer_args args;
> > +
> > + for (i = 0; i < sbi->s_ndevs; i++) {
> > + if (!bdev_is_zoned(FDEV(i).bdev))
> > + continue;
> > +
> > + args.sbi = sbi;
> > + args.fdev = &FDEV(i);
> > + ret = blkdev_report_zones(FDEV(i).bdev, 0, BLK_ALL_ZONES,
> > + check_zone_write_pointer_cb, &args);
> > + if (ret < 0)
> > + return ret;
> > + }
> > +
> > + return 0;
> > +}
> > #else
> > int f2fs_fix_curseg_write_pointer(struct f2fs_sb_info *sbi)
> > {
> > return 0;
> > }
> > +
> > +int f2fs_check_write_pointer(struct f2fs_sb_info *sbi)
> > +{
> > + return 0;
> > +}
> > #endif
> >
> > /*
> > diff --git a/fs/f2fs/super.c b/fs/f2fs/super.c
> > index 5111e1ffe58a..755ad57c795b 100644
> > --- a/fs/f2fs/super.c
> > +++ b/fs/f2fs/super.c
> > @@ -3544,6 +3544,17 @@ static int f2fs_fill_super(struct super_block *sb,
> > void *data, int silent)
> > goto free_meta;
> > }
> > }
> > +
> > + /*
> > + * If the f2fs is not readonly and fsync data recovery succeeds,
> > + * check zoned block devices' write pointer consistency.
> > + */
> > + if (!err && !f2fs_readonly(sb) && f2fs_sb_has_blkzoned(sbi)) {
> > + err = f2fs_check_write_pointer(sbi);
> > + if (err)
> > + goto free_meta;
> > + }
> > +
> > reset_checkpoint:
> > /* f2fs_recover_fsync_data() cleared this already */
> > clear_sbi_flag(sbi, SBI_POR_DOING);
> >
--
Best Regards,
Shin'ichiro Kawasaki
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