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SubjectRe: [PATCH 07/19] btrfs: do sequential extent allocation in HMZONED mode
Date
On 2019/06/13 23:07, Josef Bacik wrote:
> On Fri, Jun 07, 2019 at 10:10:13PM +0900, Naohiro Aota wrote:
>> @@ -9616,7 +9701,8 @@ static int inc_block_group_ro(struct btrfs_block_group_cache *cache, int force)
>> }
>>
>> num_bytes = cache->key.offset - cache->reserved - cache->pinned -
>> - cache->bytes_super - btrfs_block_group_used(&cache->item);
>> + cache->bytes_super - cache->unusable -
>> + btrfs_block_group_used(&cache->item);
>> sinfo_used = btrfs_space_info_used(sinfo, true);
>>
>> if (sinfo_used + num_bytes + min_allocable_bytes <=
>> @@ -9766,6 +9852,7 @@ void btrfs_dec_block_group_ro(struct btrfs_block_group_cache *cache)
>> if (!--cache->ro) {
>> num_bytes = cache->key.offset - cache->reserved -
>> cache->pinned - cache->bytes_super -
>> + cache->unusable -
>> btrfs_block_group_used(&cache->item);
>
> You've done this in a few places, but not all the places, most notably
> btrfs_space_info_used() which is used in the space reservation code a lot.

I added "unsable" to struct btrfs_block_group_cache, but added
nothing to struct btrfs_space_info. Once extent is allocated and
freed in an ALLOC_SEQ Block Group, such extent is never resued
until we remove the BG. I'm accounting the size of such region
in "cache->unusable" and in "space_info->bytes_readonly". So,
btrfs_space_info_used() does not need the modify.

I admit it's confusing here. I can add "bytes_zone_unusable" to
struct btrfs_space_info, if it's better.

>> sinfo->bytes_readonly -= num_bytes;
>> list_del_init(&cache->ro_list);
>> @@ -10200,11 +10287,240 @@ static void link_block_group(struct btrfs_block_group_cache *cache)
>> }
>> }
>>
>> +static int
>> +btrfs_get_block_group_alloc_offset(struct btrfs_block_group_cache *cache)
>> +{
>> + struct btrfs_fs_info *fs_info = cache->fs_info;
>> + struct extent_map_tree *em_tree = &fs_info->mapping_tree.map_tree;
>> + struct extent_map *em;
>> + struct map_lookup *map;
>> + struct btrfs_device *device;
>> + u64 logical = cache->key.objectid;
>> + u64 length = cache->key.offset;
>> + u64 physical = 0;
>> + int ret, alloc_type;
>> + int i, j;
>> + u64 *alloc_offsets = NULL;
>> +
>> +#define WP_MISSING_DEV ((u64)-1)
>> +
>> + /* 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 */
>> + em_tree = &fs_info->mapping_tree.map_tree;
>> + 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_type = -1;
>> + 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++) {
>> + int 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 (alloc_type == -1)
>> + alloc_type = is_sequential ?
>> + BTRFS_ALLOC_SEQ : BTRFS_ALLOC_FIT;
>> +
>> + if ((is_sequential && alloc_type != BTRFS_ALLOC_SEQ) ||
>> + (!is_sequential && alloc_type == BTRFS_ALLOC_SEQ)) {
>> + btrfs_err(fs_info, "found block group of mixed zone types");
>> + ret = -EIO;
>> + goto out;
>> + }
>> +
>> + if (!is_sequential)
>> + continue;
>> +
>> + /* this zone will be used for allocation, so mark this
>> + * zone non-empty
>> + */
>> + clear_bit(physical >> device->zone_size_shift,
>> + device->empty_zones);
>> +
>> + /*
>> + * 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));
>> + ret = btrfs_get_dev_zone(device, physical, &zone, GFP_NOFS);
>> + 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_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 (alloc_type == BTRFS_ALLOC_FIT)
>> + goto out;
>> +
>> + switch (map->type & BTRFS_BLOCK_GROUP_PROFILE_MASK) {
>> + case 0: /* single */
>> + case BTRFS_BLOCK_GROUP_DUP:
>> + case BTRFS_BLOCK_GROUP_RAID1:
>> + cache->alloc_offset = WP_MISSING_DEV;
>> + for (i = 0; i < map->num_stripes; i++) {
>> + if (alloc_offsets[i] == WP_MISSING_DEV)
>> + continue;
>> + if (cache->alloc_offset == WP_MISSING_DEV)
>> + cache->alloc_offset = alloc_offsets[i];
>> + if (alloc_offsets[i] == cache->alloc_offset)
>> + continue;
>> +
>> + btrfs_err(fs_info,
>> + "write pointer mismatch: block group %llu",
>> + logical);
>> + cache->wp_broken = 1;
>> + }
>> + break;
>> + case BTRFS_BLOCK_GROUP_RAID0:
>> + cache->alloc_offset = 0;
>> + for (i = 0; i < map->num_stripes; i++) {
>> + if (alloc_offsets[i] == WP_MISSING_DEV) {
>> + btrfs_err(fs_info,
>> + "cannot recover write pointer: block group %llu",
>> + logical);
>> + cache->wp_broken = 1;
>> + continue;
>> + }
>> +
>> + if (alloc_offsets[0] < alloc_offsets[i]) {
>> + btrfs_err(fs_info,
>> + "write pointer mismatch: block group %llu",
>> + logical);
>> + cache->wp_broken = 1;
>> + continue;
>> + }
>> +
>> + cache->alloc_offset += alloc_offsets[i];
>> + }
>> + break;
>> + case BTRFS_BLOCK_GROUP_RAID10:
>> + /*
>> + * Pass1: check write pointer of RAID1 level: each pointer
>> + * should be equal.
>> + */
>> + for (i = 0; i < map->num_stripes / map->sub_stripes; i++) {
>> + int base = i*map->sub_stripes;
>> + u64 offset = WP_MISSING_DEV;
>> +
>> + for (j = 0; j < map->sub_stripes; j++) {
>> + if (alloc_offsets[base+j] == WP_MISSING_DEV)
>> + continue;
>> + if (offset == WP_MISSING_DEV)
>> + offset = alloc_offsets[base+j];
>> + if (alloc_offsets[base+j] == offset)
>> + continue;
>> +
>> + btrfs_err(fs_info,
>> + "write pointer mismatch: block group %llu",
>> + logical);
>> + cache->wp_broken = 1;
>> + }
>> + for (j = 0; j < map->sub_stripes; j++)
>> + alloc_offsets[base+j] = offset;
>> + }
>> +
>> + /* Pass2: check write pointer of RAID1 level */
>> + cache->alloc_offset = 0;
>> + for (i = 0; i < map->num_stripes / map->sub_stripes; i++) {
>> + int base = i*map->sub_stripes;
>> +
>> + if (alloc_offsets[base] == WP_MISSING_DEV) {
>> + btrfs_err(fs_info,
>> + "cannot recover write pointer: block group %llu",
>> + logical);
>> + cache->wp_broken = 1;
>> + continue;
>> + }
>> +
>> + if (alloc_offsets[0] < alloc_offsets[base]) {
>> + btrfs_err(fs_info,
>> + "write pointer mismatch: block group %llu",
>> + logical);
>> + cache->wp_broken = 1;
>> + continue;
>> + }
>> +
>> + cache->alloc_offset += alloc_offsets[base];
>> + }
>> + break;
>> + case BTRFS_BLOCK_GROUP_RAID5:
>> + case BTRFS_BLOCK_GROUP_RAID6:
>> + /* RAID5/6 is not supported yet */
>> + default:
>> + btrfs_err(fs_info, "Unsupported profile on HMZONED %llu",
>> + map->type & BTRFS_BLOCK_GROUP_PROFILE_MASK);
>> + ret = -EINVAL;
>> + goto out;
>> + }
>> +
>> +out:
>> + cache->alloc_type = alloc_type;
>> + kfree(alloc_offsets);
>> + free_extent_map(em);
>> +
>> + return ret;
>> +}
>> +
>
> Move this to the zoned device file that you create.

Sure.

>> static struct btrfs_block_group_cache *
>> btrfs_create_block_group_cache(struct btrfs_fs_info *fs_info,
>> u64 start, u64 size)
>> {
>> struct btrfs_block_group_cache *cache;
>> + int ret;
>>
>> cache = kzalloc(sizeof(*cache), GFP_NOFS);
>> if (!cache)
>> @@ -10238,6 +10554,16 @@ btrfs_create_block_group_cache(struct btrfs_fs_info *fs_info,
>> atomic_set(&cache->trimming, 0);
>> mutex_init(&cache->free_space_lock);
>> btrfs_init_full_stripe_locks_tree(&cache->full_stripe_locks_root);
>> + cache->alloc_type = BTRFS_ALLOC_FIT;
>> + cache->alloc_offset = 0;
>> +
>> + if (btrfs_fs_incompat(fs_info, HMZONED)) {
>> + ret = btrfs_get_block_group_alloc_offset(cache);
>> + if (ret) {
>> + kfree(cache);
>> + return NULL;
>> + }
>> + }
>>
>> return cache;
>> }
>> @@ -10310,6 +10636,7 @@ int btrfs_read_block_groups(struct btrfs_fs_info *info)
>> int need_clear = 0;
>> u64 cache_gen;
>> u64 feature;
>> + u64 unusable;
>> int mixed;
>>
>> feature = btrfs_super_incompat_flags(info->super_copy);
>> @@ -10415,6 +10742,26 @@ int btrfs_read_block_groups(struct btrfs_fs_info *info)
>> free_excluded_extents(cache);
>> }
>>
>> + switch (cache->alloc_type) {
>> + case BTRFS_ALLOC_FIT:
>> + unusable = cache->bytes_super;
>> + break;
>> + case BTRFS_ALLOC_SEQ:
>> + WARN_ON(cache->bytes_super != 0);
>> + unusable = cache->alloc_offset -
>> + btrfs_block_group_used(&cache->item);
>> + /* we only need ->free_space in ALLOC_SEQ BGs */
>> + cache->last_byte_to_unpin = (u64)-1;
>> + cache->cached = BTRFS_CACHE_FINISHED;
>> + cache->free_space_ctl->free_space =
>> + cache->key.offset - cache->alloc_offset;
>> + cache->unusable = unusable;
>> + free_excluded_extents(cache);
>> + break;
>> + default:
>> + BUG();
>> + }
>> +
>> ret = btrfs_add_block_group_cache(info, cache);
>> if (ret) {
>> btrfs_remove_free_space_cache(cache);
>> @@ -10425,7 +10772,7 @@ int btrfs_read_block_groups(struct btrfs_fs_info *info)
>> trace_btrfs_add_block_group(info, cache, 0);
>> update_space_info(info, cache->flags, found_key.offset,
>> btrfs_block_group_used(&cache->item),
>> - cache->bytes_super, &space_info);
>> + unusable, &space_info);
>>
>> cache->space_info = space_info;
>>
>> @@ -10438,6 +10785,9 @@ int btrfs_read_block_groups(struct btrfs_fs_info *info)
>> ASSERT(list_empty(&cache->bg_list));
>> btrfs_mark_bg_unused(cache);
>> }
>> +
>> + if (cache->wp_broken)
>> + inc_block_group_ro(cache, 1);
>> }
>>
>> list_for_each_entry_rcu(space_info, &info->space_info, list) {
>> diff --git a/fs/btrfs/free-space-cache.c b/fs/btrfs/free-space-cache.c
>> index f74dc259307b..cc69dc71f4c1 100644
>> --- a/fs/btrfs/free-space-cache.c
>> +++ b/fs/btrfs/free-space-cache.c
>> @@ -2326,8 +2326,11 @@ int __btrfs_add_free_space(struct btrfs_fs_info *fs_info,
>> u64 offset, u64 bytes)
>> {
>> struct btrfs_free_space *info;
>> + struct btrfs_block_group_cache *block_group = ctl->private;
>> int ret = 0;
>>
>> + WARN_ON(block_group && block_group->alloc_type == BTRFS_ALLOC_SEQ);
>> +
>> info = kmem_cache_zalloc(btrfs_free_space_cachep, GFP_NOFS);
>> if (!info)
>> return -ENOMEM;
>> @@ -2376,6 +2379,28 @@ int __btrfs_add_free_space(struct btrfs_fs_info *fs_info,
>> return ret;
>> }
>>
>> +int __btrfs_add_free_space_seq(struct btrfs_block_group_cache *block_group,
>> + u64 bytenr, u64 size)
>> +{
>> + struct btrfs_free_space_ctl *ctl = block_group->free_space_ctl;
>> + u64 offset = bytenr - block_group->key.objectid;
>> + u64 to_free, to_unusable;
>> +
>> + spin_lock(&ctl->tree_lock);
>> + if (offset >= block_group->alloc_offset)
>> + to_free = size;
>> + else if (offset + size <= block_group->alloc_offset)
>> + to_free = 0;
>> + else
>> + to_free = offset + size - block_group->alloc_offset;
>> + to_unusable = size - to_free;
>> + ctl->free_space += to_free;
>> + block_group->unusable += to_unusable;
>> + spin_unlock(&ctl->tree_lock);
>> + return 0;
>> +
>> +}
>> +
>> int btrfs_remove_free_space(struct btrfs_block_group_cache *block_group,
>> u64 offset, u64 bytes)
>> {
>> @@ -2384,6 +2409,8 @@ int btrfs_remove_free_space(struct btrfs_block_group_cache *block_group,
>> int ret;
>> bool re_search = false;
>>
>> + WARN_ON(block_group->alloc_type == BTRFS_ALLOC_SEQ);
>> +
>
> These should probably be ASSERT() right? Want to make sure the developers
> really notice a problem when testing. Thanks,
>
> Josef
>

Agree. I will use ASSERT.


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