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Subject[RFC PATCH 02/17] btrfs: Get zone information of zoned block devices
Date
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(). To
avoid costly run-time zone reports 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 <naota@elisp.net>
---
fs/btrfs/volumes.c | 146 +++++++++++++++++++++++++++++++++++++++++++++
fs/btrfs/volumes.h | 32 ++++++++++
2 files changed, 178 insertions(+)

diff --git a/fs/btrfs/volumes.c b/fs/btrfs/volumes.c
index da86706123ff..35b3a2187653 100644
--- a/fs/btrfs/volumes.c
+++ b/fs/btrfs/volumes.c
@@ -677,6 +677,134 @@ static void btrfs_free_stale_devices(const char *path,
}
}

+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 >> 9,
+ z, nr_zones, gfp_mask);
+ if (ret != 0) {
+ pr_err("BTRFS: Get zone at %llu failed %d\n",
+ pos, ret);
+ return ret;
+ }
+
+ *zones = z;
+
+ return 0;
+}
+
+static void btrfs_drop_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;
+}
+
+static 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) << 9;
+ 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 << 9,
+ &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) {
+ pr_err("BTRFS: Inconsistent number of zones (%u / %u)\n",
+ n, device->nr_zones);
+ ret = -EIO;
+ goto out;
+ }
+
+ pr_info("BTRFS: 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 >> 9);
+
+out:
+ kfree(zones);
+
+ if (ret)
+ btrfs_drop_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)
@@ -726,6 +854,13 @@ 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 */
+ if (bdev_is_zoned(bdev)) {
+ 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) {
@@ -1012,6 +1147,7 @@ static void btrfs_close_bdev(struct btrfs_device *device)
}

blkdev_put(device->bdev, device->mode);
+ btrfs_drop_dev_zonetypes(device);
}

static void btrfs_close_one_device(struct btrfs_device *device)
@@ -2439,6 +2575,15 @@ 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 */
+ if (bdev_is_zoned(bdev)) {
+ 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, fs_info);
@@ -2504,6 +2649,7 @@ int btrfs_init_new_device(struct btrfs_fs_info *fs_info, const char *device_path
return ret;

error_sysfs:
+ btrfs_drop_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 23e9285d88de..13d59bff204f 100644
--- a/fs/btrfs/volumes.h
+++ b/fs/btrfs/volumes.h
@@ -61,6 +61,16 @@ 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;
+
/* the mode sent to blkdev_get */
fmode_t mode;

@@ -404,6 +414,8 @@ blk_status_t btrfs_map_bio(struct btrfs_fs_info *fs_info, struct bio *bio,
int mirror_num, int async_submit);
int btrfs_open_devices(struct btrfs_fs_devices *fs_devices,
fmode_t flags, void *holder);
+int btrfs_get_dev_zone(struct btrfs_device *device, u64 pos,
+ struct blk_zone *zone, gfp_t gfp_mask);
struct btrfs_device *btrfs_scan_one_device(const char *path,
fmode_t flags, void *holder);
int btrfs_close_devices(struct btrfs_fs_devices *fs_devices);
@@ -466,6 +478,26 @@ int btrfs_finish_chunk_alloc(struct btrfs_trans_handle *trans,
u64 chunk_offset, u64 chunk_size);
int btrfs_remove_chunk(struct btrfs_trans_handle *trans, u64 chunk_offset);

+static inline int btrfs_dev_is_sequential(struct btrfs_device *device, u64 pos)
+{
+ unsigned int zno = pos >> device->zone_size_shift;
+
+ if (!device->seq_zones)
+ return 1;
+
+ return test_bit(zno, device->seq_zones);
+}
+
+static inline int btrfs_dev_is_empty_zone(struct btrfs_device *device, u64 pos)
+{
+ unsigned int zno = pos >> device->zone_size_shift;
+
+ if (!device->empty_zones)
+ return 0;
+
+ return test_bit(zno, device->empty_zones);
+}
+
static inline void btrfs_dev_stat_inc(struct btrfs_device *dev,
int index)
{
--
2.18.0
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