From a94794d50d788d4735fd8f656ac8c0510117457d Mon Sep 17 00:00:00 2001 From: Naohiro Aota Date: Thu, 4 Feb 2021 19:21:51 +0900 Subject: btrfs: zoned: calculate allocation offset for conventional zones Conventional zones do not have a write pointer, so we cannot use it to determine the allocation offset for sequential allocation if a block group contains a conventional zone. But instead, we can consider the end of the highest addressed extent in the block group for the allocation offset. For new block group, we cannot calculate the allocation offset by consulting the extent tree, because it can cause deadlock by taking extent buffer lock after chunk mutex, which is already taken in btrfs_make_block_group(). Since it is a new block group anyways, we can simply set the allocation offset to 0. Reviewed-by: Josef Bacik Reviewed-by: Anand Jain Signed-off-by: Naohiro Aota Signed-off-by: David Sterba --- fs/btrfs/zoned.c | 99 +++++++++++++++++++++++++++++++++++++++++++++++++++++--- 1 file changed, 94 insertions(+), 5 deletions(-) (limited to 'fs/btrfs/zoned.c') diff --git a/fs/btrfs/zoned.c b/fs/btrfs/zoned.c index 0a7cd00f405f..b892566a1c93 100644 --- a/fs/btrfs/zoned.c +++ b/fs/btrfs/zoned.c @@ -927,7 +927,68 @@ 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) +/* + * Calculate an allocation pointer from the extent allocation information + * for a block group consist of conventional zones. It is pointed to the + * end of the highest addressed extent in the block group as an allocation + * offset. + */ +static int calculate_alloc_pointer(struct btrfs_block_group *cache, + u64 *offset_ret) +{ + struct btrfs_fs_info *fs_info = cache->fs_info; + struct btrfs_root *root = fs_info->extent_root; + struct btrfs_path *path; + struct btrfs_key key; + struct btrfs_key found_key; + int ret; + u64 length; + + path = btrfs_alloc_path(); + if (!path) + return -ENOMEM; + + key.objectid = cache->start + cache->length; + key.type = 0; + key.offset = 0; + + ret = btrfs_search_slot(NULL, root, &key, path, 0, 0); + /* We should not find the exact match */ + if (!ret) + ret = -EUCLEAN; + if (ret < 0) + goto out; + + ret = btrfs_previous_extent_item(root, path, cache->start); + if (ret) { + if (ret == 1) { + ret = 0; + *offset_ret = 0; + } + goto out; + } + + btrfs_item_key_to_cpu(path->nodes[0], &found_key, path->slots[0]); + + if (found_key.type == BTRFS_EXTENT_ITEM_KEY) + length = found_key.offset; + else + length = fs_info->nodesize; + + if (!(found_key.objectid >= cache->start && + found_key.objectid + length <= cache->start + cache->length)) { + ret = -EUCLEAN; + goto out; + } + *offset_ret = found_key.objectid + length - cache->start; + ret = 0; + +out: + btrfs_free_path(path); + return ret; +} + +int btrfs_load_block_group_zone_info(struct btrfs_block_group *cache, bool new) { struct btrfs_fs_info *fs_info = cache->fs_info; struct extent_map_tree *em_tree = &fs_info->mapping_tree; @@ -941,6 +1002,7 @@ int btrfs_load_block_group_zone_info(struct btrfs_block_group *cache) int i; unsigned int nofs_flag; u64 *alloc_offsets = NULL; + u64 last_alloc = 0; u32 num_sequential = 0, num_conventional = 0; if (!btrfs_is_zoned(fs_info)) @@ -1040,11 +1102,30 @@ int btrfs_load_block_group_zone_info(struct btrfs_block_group *cache) if (num_conventional > 0) { /* - * Since conventional zones do not have a write pointer, we - * cannot determine alloc_offset from the pointer + * Avoid calling calculate_alloc_pointer() for new BG. It + * is no use for new BG. It must be always 0. + * + * Also, we have a lock chain of extent buffer lock -> + * chunk mutex. For new BG, this function is called from + * btrfs_make_block_group() which is already taking the + * chunk mutex. Thus, we cannot call + * calculate_alloc_pointer() which takes extent buffer + * locks to avoid deadlock. */ - ret = -EINVAL; - goto out; + if (new) { + cache->alloc_offset = 0; + goto out; + } + ret = calculate_alloc_pointer(cache, &last_alloc); + if (ret || map->num_stripes == num_conventional) { + if (!ret) + cache->alloc_offset = last_alloc; + else + btrfs_err(fs_info, + "zoned: failed to determine allocation offset of bg %llu", + cache->start); + goto out; + } } switch (map->type & BTRFS_BLOCK_GROUP_PROFILE_MASK) { @@ -1066,6 +1147,14 @@ int btrfs_load_block_group_zone_info(struct btrfs_block_group *cache) } out: + /* An extent is allocated after the write pointer */ + if (!ret && num_conventional && last_alloc > cache->alloc_offset) { + btrfs_err(fs_info, + "zoned: got wrong write pointer in BG %llu: %llu > %llu", + logical, last_alloc, cache->alloc_offset); + ret = -EIO; + } + kfree(alloc_offsets); free_extent_map(em); -- cgit v1.2.3