On 2020/05/23 0:39, Hannes Reinecke wrote:
> Checking the teriary superblock just consists of validating UUIDs,
s/teriary/tertiary
> crcs, and the generation number; it doesn't have contents which
> would be required during the actual operation.
> So we should use an on-stack superblock and avoid having to store
> it together with the 'real' superblocks.
...a temoprary in-memory superblock allocation...
The entire structure should not be on stack... see below.
>
> Signed-off-by: Hannes Reinecke <hare@xxxxxxx>
> ---
> drivers/md/dm-zoned-metadata.c | 98 +++++++++++++++++++++++-------------------
> 1 file changed, 53 insertions(+), 45 deletions(-)
>
> diff --git a/drivers/md/dm-zoned-metadata.c b/drivers/md/dm-zoned-metadata.c
> index 3da6702bb1ae..b70a988fa771 100644
> --- a/drivers/md/dm-zoned-metadata.c
> +++ b/drivers/md/dm-zoned-metadata.c
> @@ -174,7 +174,7 @@ struct dmz_metadata {
> /* Zone information array */
> struct xarray zones;
>
> - struct dmz_sb sb[3];
> + struct dmz_sb sb[2];
> unsigned int mblk_primary;
> unsigned int sb_version;
> u64 sb_gen;
> @@ -995,10 +995,11 @@ int dmz_flush_metadata(struct dmz_metadata *zmd)
> /*
> * Check super block.
> */
> -static int dmz_check_sb(struct dmz_metadata *zmd, unsigned int set)
> +static int dmz_check_sb(struct dmz_metadata *zmd, struct dmz_sb *dsb,
> + bool tertiary)
> {
> - struct dmz_super *sb = zmd->sb[set].sb;
> - struct dmz_dev *dev = zmd->sb[set].dev;
> + struct dmz_super *sb = dsb->sb;
> + struct dmz_dev *dev = dsb->dev;
> unsigned int nr_meta_zones, nr_data_zones;
> u32 crc, stored_crc;
> u64 gen;
> @@ -1015,7 +1016,7 @@ static int dmz_check_sb(struct dmz_metadata *zmd, unsigned int set)
> DMZ_META_VER, zmd->sb_version);
> return -EINVAL;
> }
> - if ((zmd->sb_version < 1) && (set == 2)) {
> + if ((zmd->sb_version < 1) && tertiary) {
> dmz_dev_err(dev, "Tertiary superblocks are not supported");
> return -EINVAL;
> }
> @@ -1059,7 +1060,7 @@ static int dmz_check_sb(struct dmz_metadata *zmd, unsigned int set)
> return -ENXIO;
> }
>
> - if (set == 2) {
> + if (tertiary) {
> /*
> * Generation number should be 0, but it doesn't
> * really matter if it isn't.
> @@ -1108,13 +1109,13 @@ static int dmz_check_sb(struct dmz_metadata *zmd, unsigned int set)
> /*
> * Read the first or second super block from disk.
> */
> -static int dmz_read_sb(struct dmz_metadata *zmd, unsigned int set)
> +static int dmz_read_sb(struct dmz_metadata *zmd, struct dmz_sb *sb, int set)
> {
> DMDEBUG("(%s): read superblock set %d dev %s block %llu",
> zmd->devname, set, zmd->sb[set].dev->name,
> zmd->sb[set].block);
> - return dmz_rdwr_block(zmd->sb[set].dev, REQ_OP_READ,
> - zmd->sb[set].block, zmd->sb[set].mblk->page);
> + return dmz_rdwr_block(sb->dev, REQ_OP_READ,
> + sb->block, sb->mblk->page);
> }
>
> /*
> @@ -1142,7 +1143,7 @@ static int dmz_lookup_secondary_sb(struct dmz_metadata *zmd)
> zmd->sb[1].zone = xa_load(&zmd->zones, zone_id + 1);
> zmd->sb[1].dev = dmz_zone_to_dev(zmd, zmd->sb[1].zone);
> for (i = 1; i < zmd->nr_rnd_zones; i++) {
> - if (dmz_read_sb(zmd, 1) != 0)
> + if (dmz_read_sb(zmd, &zmd->sb[1], 1) != 0)
> break;
> if (le32_to_cpu(zmd->sb[1].sb->magic) == DMZ_MAGIC)
> return 0;
> @@ -1160,9 +1161,9 @@ static int dmz_lookup_secondary_sb(struct dmz_metadata *zmd)
> }
>
> /*
> - * Read the first or second super block from disk.
> + * Read a super block from disk.
> */
> -static int dmz_get_sb(struct dmz_metadata *zmd, unsigned int set)
> +static int dmz_get_sb(struct dmz_metadata *zmd, struct dmz_sb *sb, int set)
> {
> struct dmz_mblock *mblk;
> int ret;
> @@ -1172,14 +1173,14 @@ static int dmz_get_sb(struct dmz_metadata *zmd, unsigned int set)
> if (!mblk)
> return -ENOMEM;
>
> - zmd->sb[set].mblk = mblk;
> - zmd->sb[set].sb = mblk->data;
> + sb->mblk = mblk;
> + sb->sb = mblk->data;
>
> /* Read super block */
> - ret = dmz_read_sb(zmd, set);
> + ret = dmz_read_sb(zmd, sb, set);
> if (ret) {
> dmz_free_mblock(zmd, mblk);
> - zmd->sb[set].mblk = NULL;
> + sb->mblk = NULL;
> return ret;
> }
>
> @@ -1253,13 +1254,13 @@ static int dmz_load_sb(struct dmz_metadata *zmd)
> /* Read and check the primary super block */
> zmd->sb[0].block = dmz_start_block(zmd, zmd->sb[0].zone);
> zmd->sb[0].dev = dmz_zone_to_dev(zmd, zmd->sb[0].zone);
> - ret = dmz_get_sb(zmd, 0);
> + ret = dmz_get_sb(zmd, &zmd->sb[0], 0);
> if (ret) {
> dmz_dev_err(zmd->sb[0].dev, "Read primary super block failed");
> return ret;
> }
>
> - ret = dmz_check_sb(zmd, 0);
> + ret = dmz_check_sb(zmd, &zmd->sb[0], false);
>
> /* Read and check secondary super block */
> if (ret == 0) {
> @@ -1272,7 +1273,7 @@ static int dmz_load_sb(struct dmz_metadata *zmd)
> }
> zmd->sb[1].block = dmz_start_block(zmd, zmd->sb[1].zone);
> zmd->sb[1].dev = dmz_zone_to_dev(zmd, zmd->sb[1].zone);
> - ret = dmz_get_sb(zmd, 1);
> + ret = dmz_get_sb(zmd, &zmd->sb[1], 1);
> } else
> ret = dmz_lookup_secondary_sb(zmd);
>
> @@ -1281,7 +1282,7 @@ static int dmz_load_sb(struct dmz_metadata *zmd)
> return ret;
> }
>
> - ret = dmz_check_sb(zmd, 1);
> + ret = dmz_check_sb(zmd, &zmd->sb[1], false);
> if (ret == 0)
> sb_good[1] = true;
>
> @@ -1326,18 +1327,32 @@ static int dmz_load_sb(struct dmz_metadata *zmd)
> "Using super block %u (gen %llu)",
> zmd->mblk_primary, zmd->sb_gen);
>
> - if ((zmd->sb_version > 1) && zmd->sb[2].zone) {
> - zmd->sb[2].block = dmz_start_block(zmd, zmd->sb[2].zone);
> - zmd->sb[2].dev = dmz_zone_to_dev(zmd, zmd->sb[2].zone);
> - ret = dmz_get_sb(zmd, 2);
> - if (ret) {
> - dmz_dev_err(zmd->sb[2].dev,
> - "Read tertiary super block failed");
> - return ret;
> + if (zmd->sb_version > 1) {
> + int i;
> +
> + for (i = 1; i < zmd->nr_devs; i++) {
> + struct dmz_sb sb;
I would rather have dmz_get_sb() allocate this struct than have it on stack...
It is not big, but still. To be symetric, we can add dmz_put_sb() for freeing it.
> +
> + sb.block = 0;
> + sb.zone = dmz_get(zmd, zmd->dev[i].zone_offset);
> + sb.dev = &zmd->dev[i];
> + if (!dmz_is_meta(sb.zone)) {
> + dmz_dev_err(sb.dev,
> + "Tertiary super block zone %u not marked as metadata zone",
> + sb.zone->id);
> + return -EINVAL;
> + }
> + ret = dmz_get_sb(zmd, &sb, i + 1);
> + if (ret) {
> + dmz_dev_err(sb.dev,
> + "Read tertiary super block failed");
> + return ret;
> + }
> + ret = dmz_check_sb(zmd, &sb, true);
> + dmz_free_mblock(zmd, sb.mblk);
> + if (ret == -EINVAL)
> + return ret;
> }
> - ret = dmz_check_sb(zmd, 2);
> - if (ret == -EINVAL)
> - return ret;
> }
> return 0;
> }
> @@ -1402,12 +1417,15 @@ static int dmz_init_zone(struct blk_zone *blkz, unsigned int num, void *data)
> zmd->sb[0].zone = zone;
> }
> }
> - if (zmd->nr_devs > 1 && !zmd->sb[2].zone) {
> - /* Tertiary superblock zone */
> - zmd->sb[2].zone = zone;
> + if (zmd->nr_devs > 1 && num == 0) {
> + /*
> + * Tertiary superblock zones are always at the
> + * start of the zoned devices, so mark them
> + * as metadata zone.
> + */
> + set_bit(DMZ_META, &zone->flags);
> }
> }
> -
> return 0;
> }
>
> @@ -2850,16 +2868,6 @@ int dmz_ctr_metadata(struct dmz_dev *dev, int num_dev,
> }
> set_bit(DMZ_META, &zone->flags);
> }
> - if (zmd->sb[2].zone) {
> - zone = dmz_get(zmd, zmd->sb[2].zone->id);
> - if (!zone) {
> - dmz_zmd_err(zmd,
> - "Tertiary metadata zone not present");
> - ret = -ENXIO;
> - goto err;
> - }
> - set_bit(DMZ_META, &zone->flags);
> - }
> /* Load mapping table */
> ret = dmz_load_mapping(zmd);
> if (ret)
>
--
Damien Le Moal
Western Digital Research
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