Re: [PATCH v6 02/28] btrfs: Get zone information of zoned block devices

Josef Bacik
2019-12-13T20:39:11Z

On 12/12/19 11:08 PM, Naohiro Aota wrote:
> If a zoned block device is found, get its zone information (number of zones
> and zone size) using the new helper function btrfs_get_dev_zone_info(). To
> avoid costly run-time zone report commands to test the device zones type
> during block allocation, attach the seq_zones bitmap to the device
> structure to indicate if a zone is sequential or accept random writes. Also
> it attaches the empty_zones bitmap to indicate if a zone is empty or not.
>
> This patch also introduces the helper function btrfs_dev_is_sequential() to
> test if the zone storing a block is a sequential write required zone and
> btrfs_dev_is_empty_zone() to test if the zone is a empty zone.
>
> Signed-off-by: Damien Le Moal <damien.lemoal@wdc.com>
> Signed-off-by: Naohiro Aota <naohiro.aota@wdc.com>
> ---
> fs/btrfs/Makefile | 1 +
> fs/btrfs/hmzoned.c | 168 +++++++++++++++++++++++++++++++++++++++++++++
> fs/btrfs/hmzoned.h | 92 +++++++++++++++++++++++++
> fs/btrfs/volumes.c | 18 ++++-
> fs/btrfs/volumes.h | 4 ++
> 5 files changed, 281 insertions(+), 2 deletions(-)
> create mode 100644 fs/btrfs/hmzoned.c
> create mode 100644 fs/btrfs/hmzoned.h
>
> diff --git a/fs/btrfs/Makefile b/fs/btrfs/Makefile
> index 82200dbca5ac..64aaeed397a4 100644
> --- a/fs/btrfs/Makefile
> +++ b/fs/btrfs/Makefile
> @@ -16,6 +16,7 @@ btrfs-y += super.o ctree.o extent-tree.o print-tree.o root-tree.o dir-item.o \
> btrfs-$(CONFIG_BTRFS_FS_POSIX_ACL) += acl.o
> btrfs-$(CONFIG_BTRFS_FS_CHECK_INTEGRITY) += check-integrity.o
> btrfs-$(CONFIG_BTRFS_FS_REF_VERIFY) += ref-verify.o
> +btrfs-$(CONFIG_BLK_DEV_ZONED) += hmzoned.o
>
> btrfs-$(CONFIG_BTRFS_FS_RUN_SANITY_TESTS) += tests/free-space-tests.o \
> tests/extent-buffer-tests.o tests/btrfs-tests.o \
> diff --git a/fs/btrfs/hmzoned.c b/fs/btrfs/hmzoned.c
> new file mode 100644
> index 000000000000..6a13763d2916
> --- /dev/null
> +++ b/fs/btrfs/hmzoned.c
> @@ -0,0 +1,168 @@
> +// SPDX-License-Identifier: GPL-2.0
> +/*
> + * Copyright (C) 2019 Western Digital Corporation or its affiliates.
> + * Authors:
> + * Naohiro Aota <naohiro.aota@wdc.com>
> + * Damien Le Moal <damien.lemoal@wdc.com>
> + */
> +
> +#include <linux/slab.h>
> +#include <linux/blkdev.h>
> +#include "ctree.h"
> +#include "volumes.h"
> +#include "hmzoned.h"
> +#include "rcu-string.h"
> +
> +/* Maximum number of zones to report per blkdev_report_zones() call */
> +#define BTRFS_REPORT_NR_ZONES 4096
> +
> +static int btrfs_get_dev_zones(struct btrfs_device *device, u64 pos,
> + struct blk_zone *zones, unsigned int *nr_zones)
> +{
> + int ret;
> +
> + ret = blkdev_report_zones(device->bdev, pos >> SECTOR_SHIFT, zones,
> + nr_zones);
> + if (ret != 0) {
> + btrfs_err_in_rcu(device->fs_info,
> + "get zone at %llu on %s failed %d", pos,
> + rcu_str_deref(device->name), ret);
> + return ret;
> + }
> + if (!*nr_zones)
> + return -EIO;
> +
> + return 0;
> +}
> +
> +int btrfs_get_dev_zone_info(struct btrfs_device *device)
> +{
> + struct btrfs_zoned_device_info *zone_info = NULL;
> + struct block_device *bdev = device->bdev;
> + sector_t nr_sectors = bdev->bd_part->nr_sects;
> + sector_t sector = 0;
> + struct blk_zone *zones = NULL;
> + unsigned int i, nreported = 0, nr_zones;
> + unsigned int zone_sectors;
> + int ret;
> + char devstr[sizeof(device->fs_info->sb->s_id) +
> + sizeof(" (device )") - 1];
> +
> + if (!bdev_is_zoned(bdev))
> + return 0;
> +
> + zone_info = kzalloc(sizeof(*zone_info), GFP_KERNEL);
> + if (!zone_info)
> + return -ENOMEM;
> +
> + zone_sectors = bdev_zone_sectors(bdev);
> + ASSERT(is_power_of_2(zone_sectors));
> + zone_info->zone_size = (u64)zone_sectors << SECTOR_SHIFT;
> + zone_info->zone_size_shift = ilog2(zone_info->zone_size);
> + zone_info->nr_zones = nr_sectors >> ilog2(bdev_zone_sectors(bdev));
> + if (!IS_ALIGNED(nr_sectors, zone_sectors))
> + zone_info->nr_zones++;
> +
> + zone_info->seq_zones = bitmap_zalloc(zone_info->nr_zones, GFP_KERNEL);
> + if (!zone_info->seq_zones) {
> + ret = -ENOMEM;
> + goto free_zone_info;
> + }
> +
> + zone_info->empty_zones = bitmap_zalloc(zone_info->nr_zones, GFP_KERNEL);
> + if (!zone_info->empty_zones) {
> + ret = -ENOMEM;
> + goto free_seq_zones;
> + }
> +
> + zones = kcalloc(BTRFS_REPORT_NR_ZONES,
> + sizeof(struct blk_zone), GFP_KERNEL);
> + if (!zones) {
> + ret = -ENOMEM;
> + goto free_empty_zones;
> + }
> +
> + /* Get zones type */
> + while (sector < nr_sectors) {
> + nr_zones = BTRFS_REPORT_NR_ZONES;
> + ret = btrfs_get_dev_zones(device, sector << SECTOR_SHIFT, zones,
> + &nr_zones);
> + if (ret)
> + goto free_zones;
> +
> + for (i = 0; i < nr_zones; i++) {
> + if (zones[i].type == BLK_ZONE_TYPE_SEQWRITE_REQ)
> + set_bit(nreported, zone_info->seq_zones);
> + if (zones[i].cond == BLK_ZONE_COND_EMPTY)
> + set_bit(nreported, zone_info->empty_zones);
> + nreported++;
> + }
> + sector = zones[nr_zones - 1].start + zones[nr_zones - 1].len;
> + }
> +
> + if (nreported != zone_info->nr_zones) {
> + btrfs_err_in_rcu(device->fs_info,
> + "inconsistent number of zones on %s (%u / %u)",
> + rcu_str_deref(device->name), nreported,
> + zone_info->nr_zones);
> + ret = -EIO;
> + goto free_zones;
> + }
> +
> + kfree(zones);
> +
> + device->zone_info = zone_info;
> +
> + devstr[0] = 0;
> + if (device->fs_info)
> + snprintf(devstr, sizeof(devstr), " (device %s)",
> + device->fs_info->sb->s_id);
> +
> + rcu_read_lock();
> + pr_info(
> +"BTRFS info%s: host-%s zoned block device %s, %u zones of %llu sectors",
> + devstr,
> + bdev_zoned_model(bdev) == BLK_ZONED_HM ? "managed" : "aware",
> + rcu_str_deref(device->name), zone_info->nr_zones,
> + zone_info->zone_size >> SECTOR_SHIFT);
> + rcu_read_unlock();
> +
> + return 0;
> +
> +free_zones:
> + kfree(zones);
> +free_empty_zones:
> + bitmap_free(zone_info->empty_zones);
> +free_seq_zones:
> + bitmap_free(zone_info->seq_zones);
> +free_zone_info:

bitmap_free is just a kfree which handles NULL pointers properly, so you only
need one goto here for cleaning up the zone_info. Once that's fixed you can add

Reviewed-by: Josef Bacik <josef@toxicpanda.com>

Josef