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    SubjectRe: [PATCH 02/19] btrfs: Get zone information of zoned block devices
    On Fri, Jun 07, 2019 at 10:10:08PM +0900, 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_zonetypes(). To
    > avoid costly run-time zone report commands to test the device zones type
    > during block allocation, attach the seqzones bitmap to the device structure
    > to indicate if a zone is sequential or accept random writes.
    >
    > 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.
    >
    > Signed-off-by: Damien Le Moal <damien.lemoal@wdc.com>
    > Signed-off-by: Naohiro Aota <naohiro.aota@wdc.com>
    > ---
    > fs/btrfs/volumes.c | 143 +++++++++++++++++++++++++++++++++++++++++++++
    > fs/btrfs/volumes.h | 33 +++++++++++
    > 2 files changed, 176 insertions(+)
    >
    > diff --git a/fs/btrfs/volumes.c b/fs/btrfs/volumes.c
    > index 1c2a6e4b39da..b673178718e3 100644
    > --- a/fs/btrfs/volumes.c
    > +++ b/fs/btrfs/volumes.c
    > @@ -786,6 +786,135 @@ static int btrfs_free_stale_devices(const char *path,
    > return ret;
    > }
    >
    > +static int __btrfs_get_dev_zones(struct btrfs_device *device, u64 pos,
    > + struct blk_zone **zones,
    > + unsigned int *nr_zones, gfp_t gfp_mask)
    > +{
    > + struct blk_zone *z = *zones;
    > + int ret;
    > +
    > + if (!z) {
    > + z = kcalloc(*nr_zones, sizeof(struct blk_zone), GFP_KERNEL);
    > + if (!z)
    > + return -ENOMEM;
    > + }
    > +
    > + ret = blkdev_report_zones(device->bdev, pos >> SECTOR_SHIFT,
    > + z, nr_zones, gfp_mask);
    > + if (ret != 0) {
    > + btrfs_err(device->fs_info, "Get zone at %llu failed %d\n",
    > + pos, ret);
    > + return ret;
    > + }
    > +
    > + *zones = z;
    > +
    > + return 0;
    > +}
    > +
    > +static void btrfs_destroy_dev_zonetypes(struct btrfs_device *device)
    > +{
    > + kfree(device->seq_zones);
    > + kfree(device->empty_zones);
    > + device->seq_zones = NULL;
    > + device->empty_zones = NULL;
    > + device->nr_zones = 0;
    > + device->zone_size = 0;
    > + device->zone_size_shift = 0;
    > +}
    > +
    > +int btrfs_get_dev_zone(struct btrfs_device *device, u64 pos,
    > + struct blk_zone *zone, gfp_t gfp_mask)
    > +{
    > + unsigned int nr_zones = 1;
    > + int ret;
    > +
    > + ret = __btrfs_get_dev_zones(device, pos, &zone, &nr_zones, gfp_mask);
    > + if (ret != 0 || !nr_zones)
    > + return ret ? ret : -EIO;
    > +
    > + return 0;
    > +}
    > +
    > +int btrfs_get_dev_zonetypes(struct btrfs_device *device)
    > +{
    > + 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, n = 0, nr_zones;
    > + int ret;
    > +
    > + device->zone_size = 0;
    > + device->zone_size_shift = 0;
    > + device->nr_zones = 0;
    > + device->seq_zones = NULL;
    > + device->empty_zones = NULL;
    > +
    > + if (!bdev_is_zoned(bdev))
    > + return 0;
    > +
    > + device->zone_size = (u64)bdev_zone_sectors(bdev) << SECTOR_SHIFT;
    > + device->zone_size_shift = ilog2(device->zone_size);
    > + device->nr_zones = nr_sectors >> ilog2(bdev_zone_sectors(bdev));
    > + if (nr_sectors & (bdev_zone_sectors(bdev) - 1))
    > + device->nr_zones++;
    > +
    > + device->seq_zones = kcalloc(BITS_TO_LONGS(device->nr_zones),
    > + sizeof(*device->seq_zones), GFP_KERNEL);
    > + if (!device->seq_zones)
    > + return -ENOMEM;
    > +
    > + device->empty_zones = kcalloc(BITS_TO_LONGS(device->nr_zones),
    > + sizeof(*device->empty_zones), GFP_KERNEL);
    > + if (!device->empty_zones)
    > + return -ENOMEM;
    > +
    > +#define BTRFS_REPORT_NR_ZONES 4096
    > +
    > + /* 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, GFP_KERNEL);
    > + if (ret != 0 || !nr_zones) {
    > + if (!ret)
    > + ret = -EIO;
    > + goto out;
    > + }
    > +
    > + for (i = 0; i < nr_zones; i++) {
    > + if (zones[i].type == BLK_ZONE_TYPE_SEQWRITE_REQ)
    > + set_bit(n, device->seq_zones);
    > + if (zones[i].cond == BLK_ZONE_COND_EMPTY)
    > + set_bit(n, device->empty_zones);
    > + sector = zones[i].start + zones[i].len;
    > + n++;
    > + }
    > + }
    > +
    > + if (n != device->nr_zones) {
    > + btrfs_err(device->fs_info,
    > + "Inconsistent number of zones (%u / %u)\n", n,
    > + device->nr_zones);
    > + ret = -EIO;
    > + goto out;
    > + }
    > +
    > + btrfs_info(device->fs_info,
    > + "host-%s zoned block device, %u zones of %llu sectors\n",
    > + bdev_zoned_model(bdev) == BLK_ZONED_HM ? "managed" : "aware",
    > + device->nr_zones, device->zone_size >> SECTOR_SHIFT);
    > +
    > +out:
    > + kfree(zones);
    > +
    > + if (ret)
    > + btrfs_destroy_dev_zonetypes(device);
    > +
    > + return ret;
    > +}
    > +
    > static int btrfs_open_one_device(struct btrfs_fs_devices *fs_devices,
    > struct btrfs_device *device, fmode_t flags,
    > void *holder)
    > @@ -842,6 +971,11 @@ static int btrfs_open_one_device(struct btrfs_fs_devices *fs_devices,
    > clear_bit(BTRFS_DEV_STATE_IN_FS_METADATA, &device->dev_state);
    > device->mode = flags;
    >
    > + /* Get zone type information of zoned block devices */
    > + ret = btrfs_get_dev_zonetypes(device);
    > + if (ret != 0)
    > + goto error_brelse;
    > +
    > fs_devices->open_devices++;
    > if (test_bit(BTRFS_DEV_STATE_WRITEABLE, &device->dev_state) &&
    > device->devid != BTRFS_DEV_REPLACE_DEVID) {
    > @@ -1243,6 +1377,7 @@ static void btrfs_close_bdev(struct btrfs_device *device)
    > }
    >
    > blkdev_put(device->bdev, device->mode);
    > + btrfs_destroy_dev_zonetypes(device);
    > }
    >
    > static void btrfs_close_one_device(struct btrfs_device *device)
    > @@ -2664,6 +2799,13 @@ int btrfs_init_new_device(struct btrfs_fs_info *fs_info, const char *device_path
    > mutex_unlock(&fs_info->chunk_mutex);
    > mutex_unlock(&fs_devices->device_list_mutex);
    >
    > + /* Get zone type information of zoned block devices */
    > + ret = btrfs_get_dev_zonetypes(device);
    > + if (ret) {
    > + btrfs_abort_transaction(trans, ret);
    > + goto error_sysfs;
    > + }
    > +
    > if (seeding_dev) {
    > mutex_lock(&fs_info->chunk_mutex);
    > ret = init_first_rw_device(trans);
    > @@ -2729,6 +2871,7 @@ int btrfs_init_new_device(struct btrfs_fs_info *fs_info, const char *device_path
    > return ret;
    >
    > error_sysfs:
    > + btrfs_destroy_dev_zonetypes(device);
    > btrfs_sysfs_rm_device_link(fs_devices, device);
    > mutex_lock(&fs_info->fs_devices->device_list_mutex);
    > mutex_lock(&fs_info->chunk_mutex);
    > diff --git a/fs/btrfs/volumes.h b/fs/btrfs/volumes.h
    > index b8a0e8d0672d..1599641e216c 100644
    > --- a/fs/btrfs/volumes.h
    > +++ b/fs/btrfs/volumes.h
    > @@ -62,6 +62,16 @@ struct btrfs_device {
    >
    > struct block_device *bdev;
    >
    > + /*
    > + * Number of zones, zone size and types of zones if bdev is a
    > + * zoned block device.
    > + */
    > + u64 zone_size;
    > + u8 zone_size_shift;
    > + u32 nr_zones;
    > + unsigned long *seq_zones;
    > + unsigned long *empty_zones;
    > +

    Also make a struct btrfs_zone_info and have a pointer to one here if we have
    zone devices. Thanks,

    Josef

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