diff options
Diffstat (limited to 'fs/btrfs/extent-tree.c')
| -rw-r--r-- | fs/btrfs/extent-tree.c | 19 |
1 files changed, 19 insertions, 0 deletions
diff --git a/fs/btrfs/extent-tree.c b/fs/btrfs/extent-tree.c index 8b7eb22d508a..e1a39fe183c1 100644 --- a/fs/btrfs/extent-tree.c +++ b/fs/btrfs/extent-tree.c @@ -7341,6 +7341,19 @@ static u64 update_block_group_flags(struct btrfs_fs_info *fs_info, u64 flags) return flags; } +/* + * Mark block group @cache read-only, so later write won't happen to block + * group @cache. + * + * If @force is not set, this function will only mark the block group readonly + * if we have enough free space (1M) in other metadata/system block groups. + * If @force is not set, this function will mark the block group readonly + * without checking free space. + * + * NOTE: This function doesn't care if other block groups can contain all the + * data in this block group. That check should be done by relocation routine, + * not this function. + */ static int inc_block_group_ro(struct btrfs_block_group_cache *cache, int force) { struct btrfs_space_info *sinfo = cache->space_info; @@ -7374,6 +7387,12 @@ static int inc_block_group_ro(struct btrfs_block_group_cache *cache, int force) cache->bytes_super - btrfs_block_group_used(&cache->item); sinfo_used = btrfs_space_info_used(sinfo, true); + /* + * sinfo_used + num_bytes should always <= sinfo->total_bytes. + * + * Here we make sure if we mark this bg RO, we still have enough + * free space as buffer (if min_allocable_bytes is not 0). + */ if (sinfo_used + num_bytes + min_allocable_bytes <= sinfo->total_bytes) { sinfo->bytes_readonly += num_bytes; |