Re: [PATCH v9 14/41] btrfs: load zone's alloction offset

[Naohiro Aota <naohiro.aota@wdc.com>]

On Mon, Nov 02, 2020 at 03:25:42PM -0500, Josef Bacik wrote:
>On 10/30/20 9:51 AM, Naohiro Aota wrote:
>>Zoned btrfs must allocate blocks at the zones' write pointer. The device's
>>write pointer position can be mapped to a logical address within a block
>>group. This commit adds "alloc_offset" to track the logical address.
>>
>>This logical address is populated in btrfs_load_block-group_zone_info()
>
>btrfs_load_block_group_zone_info()
>

Fixed. Thanks.

>>from write pointers of corresponding zones.
>>
>>For now, zoned btrfs only support the SINGLE profile. Supporting non-SINGLE
>>profile with zone append writing is not trivial. For example, in the DUP
>>profile, we send a zone append writing IO to two zones on a device. The
>>device reply with written LBAs for the IOs. If the offsets of the returned
>>addresses from the beginning of the zone are different, then it results in
>>different logical addresses.
>>
>>We need fine-grained logical to physical mapping to support such separated
>>physical address issue. Since it should require additional metadata type,
>>disable non-SINGLE profiles for now.
>>
>>Signed-off-by: Naohiro Aota <naohiro.aota@wdc.com>
>>---
>>  fs/btrfs/block-group.c |  15 ++++
>>  fs/btrfs/block-group.h |   6 ++
>>  fs/btrfs/zoned.c       | 153 +++++++++++++++++++++++++++++++++++++++++
>>  fs/btrfs/zoned.h       |   6 ++
>>  4 files changed, 180 insertions(+)
>>
>>diff --git a/fs/btrfs/block-group.c b/fs/btrfs/block-group.c
>>index e989c66aa764..920b2708c7f2 100644
>>--- a/fs/btrfs/block-group.c
>>+++ b/fs/btrfs/block-group.c
>>@@ -15,6 +15,7 @@
>>  #include "delalloc-space.h"
>>  #include "discard.h"
>>  #include "raid56.h"
>>+#include "zoned.h"
>>  /*
>>   * Return target flags in extended format or 0 if restripe for this chunk_type
>>@@ -1935,6 +1936,13 @@ static int read_one_block_group(struct btrfs_fs_info *info,
>>  			goto error;
>>  	}
>>+	ret = btrfs_load_block_group_zone_info(cache);
>>+	if (ret) {
>>+		btrfs_err(info, "failed to load zone info of bg %llu",
>>+			  cache->start);
>>+		goto error;
>>+	}
>>+
>>  	/*
>>  	 * We need to exclude the super stripes now so that the space info has
>>  	 * super bytes accounted for, otherwise we'll think we have more space
>>@@ -2161,6 +2169,13 @@ int btrfs_make_block_group(struct btrfs_trans_handle *trans, u64 bytes_used,
>>  	cache->last_byte_to_unpin = (u64)-1;
>>  	cache->cached = BTRFS_CACHE_FINISHED;
>>  	cache->needs_free_space = 1;
>>+
>>+	ret = btrfs_load_block_group_zone_info(cache);
>>+	if (ret) {
>>+		btrfs_put_block_group(cache);
>>+		return ret;
>>+	}
>>+
>>  	ret = exclude_super_stripes(cache);
>>  	if (ret) {
>>  		/* We may have excluded something, so call this just in case */
>>diff --git a/fs/btrfs/block-group.h b/fs/btrfs/block-group.h
>>index adfd7583a17b..14e3043c9ce7 100644
>>--- a/fs/btrfs/block-group.h
>>+++ b/fs/btrfs/block-group.h
>>@@ -183,6 +183,12 @@ struct btrfs_block_group {
>>  	/* Record locked full stripes for RAID5/6 block group */
>>  	struct btrfs_full_stripe_locks_tree full_stripe_locks_root;
>>+
>>+	/*
>>+	 * Allocation offset for the block group to implement sequential
>>+	 * allocation. This is used only with ZONED mode enabled.
>>+	 */
>>+	u64 alloc_offset;
>>  };
>>  static inline u64 btrfs_block_group_end(struct btrfs_block_group *block_group)
>>diff --git a/fs/btrfs/zoned.c b/fs/btrfs/zoned.c
>>index 4411d786597a..0aa821893a51 100644
>>--- a/fs/btrfs/zoned.c
>>+++ b/fs/btrfs/zoned.c
>>@@ -3,14 +3,20 @@
>>  #include <linux/bitops.h>
>>  #include <linux/slab.h>
>>  #include <linux/blkdev.h>
>>+#include <linux/sched/mm.h>
>>  #include "ctree.h"
>>  #include "volumes.h"
>>  #include "zoned.h"
>>  #include "rcu-string.h"
>>  #include "disk-io.h"
>>+#include "block-group.h"
>>  /* Maximum number of zones to report per blkdev_report_zones() call */
>>  #define BTRFS_REPORT_NR_ZONES   4096
>>+/* Invalid allocation pointer value for missing devices */
>>+#define WP_MISSING_DEV ((u64)-1)
>>+/* Pseudo write pointer value for conventional zone */
>>+#define WP_CONVENTIONAL ((u64)-2)
>>  static int copy_zone_info_cb(struct blk_zone *zone, unsigned int idx,
>>  			     void *data)
>>@@ -733,3 +739,150 @@ int btrfs_ensure_empty_zones(struct btrfs_device *device, u64 start, u64 size)
>>  	return 0;
>>  }
>>+
>>+int btrfs_load_block_group_zone_info(struct btrfs_block_group *cache)
>>+{
>>+	struct btrfs_fs_info *fs_info = cache->fs_info;
>>+	struct extent_map_tree *em_tree = &fs_info->mapping_tree;
>>+	struct extent_map *em;
>>+	struct map_lookup *map;
>>+	struct btrfs_device *device;
>>+	u64 logical = cache->start;
>>+	u64 length = cache->length;
>>+	u64 physical = 0;
>>+	int ret;
>>+	int i;
>>+	unsigned int nofs_flag;
>>+	u64 *alloc_offsets = NULL;
>>+	u32 num_sequential = 0, num_conventional = 0;
>>+
>>+	if (!btrfs_is_zoned(fs_info))
>>+		return 0;
>>+
>>+	/* Sanity check */
>>+	if (!IS_ALIGNED(length, fs_info->zone_size)) {
>>+		btrfs_err(fs_info, "unaligned block group at %llu + %llu",
>>+			  logical, length);
>>+		return -EIO;
>>+	}
>>+
>>+	/* Get the chunk mapping */
>>+	read_lock(&em_tree->lock);
>>+	em = lookup_extent_mapping(em_tree, logical, length);
>>+	read_unlock(&em_tree->lock);
>>+
>>+	if (!em)
>>+		return -EINVAL;
>>+
>>+	map = em->map_lookup;
>>+
>>+	/*
>>+	 * Get the zone type: if the group is mapped to a non-sequential zone,
>>+	 * there is no need for the allocation offset (fit allocation is OK).
>>+	 */
>>+	alloc_offsets = kcalloc(map->num_stripes, sizeof(*alloc_offsets),
>>+				GFP_NOFS);
>>+	if (!alloc_offsets) {
>>+		free_extent_map(em);
>>+		return -ENOMEM;
>>+	}
>>+
>>+	for (i = 0; i < map->num_stripes; i++) {
>>+		bool is_sequential;
>>+		struct blk_zone zone;
>>+
>>+		device = map->stripes[i].dev;
>>+		physical = map->stripes[i].physical;
>>+
>>+		if (device->bdev == NULL) {
>>+			alloc_offsets[i] = WP_MISSING_DEV;
>>+			continue;
>>+		}
>>+
>>+		is_sequential = btrfs_dev_is_sequential(device, physical);
>>+		if (is_sequential)
>>+			num_sequential++;
>>+		else
>>+			num_conventional++;
>>+
>>+		if (!is_sequential) {
>>+			alloc_offsets[i] = WP_CONVENTIONAL;
>>+			continue;
>>+		}
>>+
>>+		/*
>>+		 * This zone will be used for allocation, so mark this
>>+		 * zone non-empty.
>>+		 */
>>+		btrfs_dev_clear_zone_empty(device, physical);
>>+
>>+		/*
>>+		 * The group is mapped to a sequential zone. Get the zone write
>>+		 * pointer to determine the allocation offset within the zone.
>>+		 */
>>+		WARN_ON(!IS_ALIGNED(physical, fs_info->zone_size));
>>+		nofs_flag = memalloc_nofs_save();
>>+		ret = btrfs_get_dev_zone(device, physical, &zone);
>>+		memalloc_nofs_restore(nofs_flag);
>>+		if (ret == -EIO || ret == -EOPNOTSUPP) {
>>+			ret = 0;
>>+			alloc_offsets[i] = WP_MISSING_DEV;
>>+			continue;
>>+		} else if (ret) {
>>+			goto out;
>>+		}
>>+
>>+		switch (zone.cond) {
>>+		case BLK_ZONE_COND_OFFLINE:
>>+		case BLK_ZONE_COND_READONLY:
>>+			btrfs_err(fs_info, "Offline/readonly zone %llu",
>>+				  physical >> device->zone_info->zone_size_shift);
>>+			alloc_offsets[i] = WP_MISSING_DEV;
>>+			break;
>>+		case BLK_ZONE_COND_EMPTY:
>>+			alloc_offsets[i] = 0;
>>+			break;
>>+		case BLK_ZONE_COND_FULL:
>>+			alloc_offsets[i] = fs_info->zone_size;
>>+			break;
>>+		default:
>>+			/* Partially used zone */
>>+			alloc_offsets[i] =
>>+				((zone.wp - zone.start) << SECTOR_SHIFT);
>>+			break;
>>+		}
>>+	}
>>+
>>+	if (num_conventional > 0) {
>>+		/*
>>+		 * Since conventional zones does not have write pointer, we
>>+		 * cannot determine alloc_offset from the pointer
>>+		 */
>>+		ret = -EINVAL;
>>+		goto out;
>>+	}
>
>Does this mean we can't have zoned with a device that has conventional 
>and sequential zones?  I thought such things existed currently?  
>Thanks,
>
>Josef