We've avoided data losing raid profile when doing balance, but it turns out that deleting a device could also result in the same problem.
This fixes the problem by creating an empty data chunk before relocating the data chunk. Metadata/System chunk are supposed to have non-zero bytes all the time so their raid profile is persistent. Reported-by: James Alandt <james.ala...@wdc.com> Signed-off-by: Liu Bo <bo.li....@oracle.com> --- v2: - return the correct error. - move helper ahead of __btrfs_balance(). fs/btrfs/volumes.c | 84 ++++++++++++++++++++++++++++++++++++++++++------------ 1 file changed, 65 insertions(+), 19 deletions(-) diff --git a/fs/btrfs/volumes.c b/fs/btrfs/volumes.c index 4a72c45..a74396d 100644 --- a/fs/btrfs/volumes.c +++ b/fs/btrfs/volumes.c @@ -3018,6 +3018,48 @@ static int btrfs_relocate_sys_chunks(struct btrfs_fs_info *fs_info) return ret; } +/* + * return 1 : allocate a data chunk successfully, + * return <0: errors during allocating a data chunk, + * return 0 : no need to allocate a data chunk. + */ +static int btrfs_may_alloc_data_chunk(struct btrfs_fs_info *fs_info, + u64 chunk_offset) +{ + struct btrfs_block_group_cache *cache; + u64 bytes_used; + u64 chunk_type; + + cache = btrfs_lookup_block_group(fs_info, chunk_offset); + ASSERT(cache); + chunk_type = cache->flags; + btrfs_put_block_group(cache); + + if (chunk_type & BTRFS_BLOCK_GROUP_DATA) { + spin_lock(&fs_info->data_sinfo->lock); + bytes_used = fs_info->data_sinfo->bytes_used; + spin_unlock(&fs_info->data_sinfo->lock); + + if (!bytes_used) { + struct btrfs_trans_handle *trans; + int ret; + + trans = btrfs_join_transaction(fs_info->tree_root); + if (IS_ERR(trans)) + return PTR_ERR(trans); + + ret = btrfs_force_chunk_alloc(trans, fs_info, + BTRFS_BLOCK_GROUP_DATA); + btrfs_end_transaction(trans); + if (ret < 0) + return ret; + + return 1; + } + } + return 0; +} + static int insert_balance_item(struct btrfs_fs_info *fs_info, struct btrfs_balance_control *bctl) { @@ -3476,7 +3518,6 @@ static int __btrfs_balance(struct btrfs_fs_info *fs_info) u32 count_meta = 0; u32 count_sys = 0; int chunk_reserved = 0; - u64 bytes_used = 0; /* step one make some room on all the devices */ devices = &fs_info->fs_devices->devices; @@ -3635,28 +3676,21 @@ static int __btrfs_balance(struct btrfs_fs_info *fs_info) goto loop; } - ASSERT(fs_info->data_sinfo); - spin_lock(&fs_info->data_sinfo->lock); - bytes_used = fs_info->data_sinfo->bytes_used; - spin_unlock(&fs_info->data_sinfo->lock); - - if ((chunk_type & BTRFS_BLOCK_GROUP_DATA) && - !chunk_reserved && !bytes_used) { - trans = btrfs_start_transaction(chunk_root, 0); - if (IS_ERR(trans)) { - mutex_unlock(&fs_info->delete_unused_bgs_mutex); - ret = PTR_ERR(trans); - goto error; - } - - ret = btrfs_force_chunk_alloc(trans, fs_info, - BTRFS_BLOCK_GROUP_DATA); - btrfs_end_transaction(trans); + if (!chunk_reserved) { + /* + * We may be relocating the only data chunk we have, + * which could potentially end up with losing data's + * raid profile, so lets allocate an empty one in + * advance. + */ + ret = btrfs_may_alloc_data_chunk(fs_info, + found_key.offset); if (ret < 0) { mutex_unlock(&fs_info->delete_unused_bgs_mutex); goto error; + } else if (ret == 1) { + chunk_reserved = 1; } - chunk_reserved = 1; } ret = btrfs_relocate_chunk(fs_info, found_key.offset); @@ -4419,6 +4453,18 @@ int btrfs_shrink_device(struct btrfs_device *device, u64 new_size) chunk_offset = btrfs_dev_extent_chunk_offset(l, dev_extent); btrfs_release_path(path); + /* + * We may be relocating the only data chunk we have, + * which could potentially end up with losing data's + * raid profile, so lets allocate an empty one in + * advance. + */ + ret = btrfs_may_alloc_data_chunk(fs_info, chunk_offset); + if (ret < 0) { + mutex_unlock(&fs_info->delete_unused_bgs_mutex); + goto done; + } + ret = btrfs_relocate_chunk(fs_info, chunk_offset); mutex_unlock(&fs_info->delete_unused_bgs_mutex); if (ret && ret != -ENOSPC) -- 2.9.4 -- To unsubscribe from this list: send the line "unsubscribe linux-btrfs" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html