On Wed, Jan 15, 2014 at 08:00:58PM +0800, Miao Xie wrote:
> When we mounted the filesystem after the crash, we got the following
> message:
> BTRFS error (device xxx): block group 4315938816 has wrong amount of free
> space
> BTRFS error (device xxx): failed to load free space cache for block group
> 4315938816
The code itself is fine.
But I'm not sure if it's worth doing so, I mean those memory allocation and lock
acquire and release in our core endio path.
To fallback to rebuild space cache is fairly acceptable to me in the case of
crash.
-liubo
>
> It is because we didn't update the metadata of the allocated space until
> the file data was written into the disk. During this time, there was no
> information about the allocated spaces in either the extent tree nor the
> free space cache. when we wrote out the free space cache at this time, those
> spaces were lost.
>
> In ordered to fix this problem, I use a state tree for every block group
> to record those allocated spaces. We record the information when they are
> allocated, and clean up the information after the metadata update. Besides
> that, we also introduce a read-write semaphore to avoid the race between
> the allocation and the free space cache write out.
>
> Only data block groups had this problem, so the above change is just
> for data space allocation.
>
> Signed-off-by: Miao Xie <mi...@cn.fujitsu.com>
> ---
> fs/btrfs/ctree.h | 15 ++++++++++++++-
> fs/btrfs/disk-io.c | 2 +-
> fs/btrfs/extent-tree.c | 24 ++++++++++++++++++++----
> fs/btrfs/free-space-cache.c | 42 ++++++++++++++++++++++++++++++++++++++----
> fs/btrfs/inode.c | 42 +++++++++++++++++++++++++++++++++++-------
> 5 files changed, 108 insertions(+), 17 deletions(-)
>
> diff --git a/fs/btrfs/ctree.h b/fs/btrfs/ctree.h
> index 1667c9a..f58e1f7 100644
> --- a/fs/btrfs/ctree.h
> +++ b/fs/btrfs/ctree.h
> @@ -1244,6 +1244,12 @@ struct btrfs_block_group_cache {
> /* free space cache stuff */
> struct btrfs_free_space_ctl *free_space_ctl;
>
> + /*
> + * It is used to record the extents that are allocated for
> + * the data, but don/t update its metadata.
> + */
> + struct extent_io_tree pinned_extents;
> +
> /* block group cache stuff */
> struct rb_node cache_node;
>
> @@ -1540,6 +1546,13 @@ struct btrfs_fs_info {
> */
> struct list_head space_info;
>
> + /*
> + * It is just used for the delayed data space allocation
> + * because only the data space allocation can be done during
> + * we write out the free space cache.
> + */
> + struct rw_semaphore data_rwsem;
> +
> struct btrfs_space_info *data_sinfo;
>
> struct reloc_control *reloc_ctl;
> @@ -3183,7 +3196,7 @@ int btrfs_alloc_logged_file_extent(struct
> btrfs_trans_handle *trans,
> struct btrfs_key *ins);
> int btrfs_reserve_extent(struct btrfs_root *root, u64 num_bytes,
> u64 min_alloc_size, u64 empty_size, u64 hint_byte,
> - struct btrfs_key *ins, int is_data);
> + struct btrfs_key *ins, int is_data, bool need_pin);
> int btrfs_inc_ref(struct btrfs_trans_handle *trans, struct btrfs_root *root,
> struct extent_buffer *buf, int full_backref, int for_cow);
> int btrfs_dec_ref(struct btrfs_trans_handle *trans, struct btrfs_root *root,
> diff --git a/fs/btrfs/disk-io.c b/fs/btrfs/disk-io.c
> index 8072cfa..426b558 100644
> --- a/fs/btrfs/disk-io.c
> +++ b/fs/btrfs/disk-io.c
> @@ -2276,7 +2276,6 @@ int open_ctree(struct super_block *sb,
> fs_info->pinned_extents = &fs_info->freed_extents[0];
> fs_info->do_barriers = 1;
>
> -
> mutex_init(&fs_info->ordered_operations_mutex);
> mutex_init(&fs_info->ordered_extent_flush_mutex);
> mutex_init(&fs_info->tree_log_mutex);
> @@ -2287,6 +2286,7 @@ int open_ctree(struct super_block *sb,
> init_rwsem(&fs_info->extent_commit_sem);
> init_rwsem(&fs_info->cleanup_work_sem);
> init_rwsem(&fs_info->subvol_sem);
> + init_rwsem(&fs_info->data_rwsem);
> sema_init(&fs_info->uuid_tree_rescan_sem, 1);
> fs_info->dev_replace.lock_owner = 0;
> atomic_set(&fs_info->dev_replace.nesting_level, 0);
> diff --git a/fs/btrfs/extent-tree.c b/fs/btrfs/extent-tree.c
> index 3664cfb..7b07876 100644
> --- a/fs/btrfs/extent-tree.c
> +++ b/fs/btrfs/extent-tree.c
> @@ -6173,7 +6173,7 @@ enum btrfs_loop_type {
> static noinline int find_free_extent(struct btrfs_root *orig_root,
> u64 num_bytes, u64 empty_size,
> u64 hint_byte, struct btrfs_key *ins,
> - u64 flags)
> + u64 flags, bool need_pin)
> {
> int ret = 0;
> struct btrfs_root *root = orig_root->fs_info->extent_root;
> @@ -6502,6 +6502,16 @@ checks:
> ins->objectid = search_start;
> ins->offset = num_bytes;
>
> + if (need_pin) {
> + ASSERT(search_start >= block_group->key.objectid &&
> + search_start < block_group->key.objectid +
> + block_group->key.offset);
> + set_extent_dirty(&block_group->pinned_extents,
> + search_start,
> + search_start + num_bytes - 1,
> + GFP_NOFS);
> + }
> +
> trace_btrfs_reserve_extent(orig_root, block_group,
> search_start, num_bytes);
> btrfs_put_block_group(block_group);
> @@ -6614,17 +6624,20 @@ again:
> int btrfs_reserve_extent(struct btrfs_root *root,
> u64 num_bytes, u64 min_alloc_size,
> u64 empty_size, u64 hint_byte,
> - struct btrfs_key *ins, int is_data)
> + struct btrfs_key *ins, int is_data, bool need_pin)
> {
> bool final_tried = false;
> u64 flags;
> int ret;
>
> flags = btrfs_get_alloc_profile(root, is_data);
> +
> + if (need_pin)
> + down_read(&root->fs_info->data_rwsem);
> again:
> WARN_ON(num_bytes < root->sectorsize);
> ret = find_free_extent(root, num_bytes, empty_size, hint_byte, ins,
> - flags);
> + flags, need_pin);
>
> if (ret == -ENOSPC) {
> if (!final_tried && ins->offset) {
> @@ -6645,6 +6658,8 @@ again:
> }
> }
>
> + if (need_pin)
> + up_read(&root->fs_info->data_rwsem);
> return ret;
> }
>
> @@ -7016,7 +7031,7 @@ struct extent_buffer *btrfs_alloc_free_block(struct
> btrfs_trans_handle *trans,
> return ERR_CAST(block_rsv);
>
> ret = btrfs_reserve_extent(root, blocksize, blocksize,
> - empty_size, hint, &ins, 0);
> + empty_size, hint, &ins, 0, false);
> if (ret) {
> unuse_block_rsv(root->fs_info, block_rsv, blocksize);
> return ERR_PTR(ret);
> @@ -8387,6 +8402,7 @@ btrfs_create_block_group_cache(struct btrfs_root *root,
> u64 start, u64 size)
> INIT_LIST_HEAD(&cache->cluster_list);
> INIT_LIST_HEAD(&cache->new_bg_list);
> btrfs_init_free_space_ctl(cache);
> + extent_io_tree_init(&cache->pinned_extents, NULL);
>
> return cache;
> }
> diff --git a/fs/btrfs/free-space-cache.c b/fs/btrfs/free-space-cache.c
> index 057be95..486e12a3 100644
> --- a/fs/btrfs/free-space-cache.c
> +++ b/fs/btrfs/free-space-cache.c
> @@ -875,6 +875,7 @@ static int __btrfs_write_out_cache(struct btrfs_root
> *root, struct inode *inode,
> struct rb_node *node;
> struct list_head *pos, *n;
> struct extent_state *cached_state = NULL;
> + struct extent_state *pinned_extent = NULL;
> struct btrfs_free_cluster *cluster = NULL;
> struct extent_io_tree *unpin = NULL;
> struct io_ctl io_ctl;
> @@ -948,17 +949,17 @@ static int __btrfs_write_out_cache(struct btrfs_root
> *root, struct inode *inode,
> * so we don't leak the space
> */
>
> + if (!block_group)
> + goto bitmap;
> /*
> * We shouldn't have switched the pinned extents yet so this is the
> * right one
> */
> unpin = root->fs_info->pinned_extents;
>
> - if (block_group)
> - start = block_group->key.objectid;
> + start = block_group->key.objectid;
>
> - while (block_group && (start < block_group->key.objectid +
> - block_group->key.offset)) {
> + while (start < block_group->key.objectid + block_group->key.offset) {
> ret = find_first_extent_bit(unpin, start,
> &extent_start, &extent_end,
> EXTENT_DIRTY, NULL);
> @@ -985,6 +986,33 @@ static int __btrfs_write_out_cache(struct btrfs_root
> *root, struct inode *inode,
> start = extent_end;
> }
>
> + if (!(block_group->flags & BTRFS_BLOCK_GROUP_DATA))
> + goto bitmap;
> +
> + start = block_group->key.objectid;
> + unpin = &block_group->pinned_extents;
> + while (1) {
> + ret = find_first_extent_bit(unpin, start,
> + &extent_start, &extent_end,
> + EXTENT_DIRTY, &pinned_extent);
> + if (ret) {
> + ret = 0;
> + break;
> + }
> +
> + len = extent_end - extent_start + 1;
> +
> + entries++;
> + ret = io_ctl_add_entry(&io_ctl, extent_start, len, NULL);
> + if (ret) {
> + free_extent_state(pinned_extent);
> + goto out_nospc;
> + }
> +
> + start = extent_end + 1;
> + }
> + free_extent_state(pinned_extent);
> +bitmap:
> /* Write out the bitmaps */
> list_for_each_safe(pos, n, &bitmap_list) {
> struct btrfs_free_space *entry =
> @@ -1097,6 +1125,9 @@ int btrfs_write_out_cache(struct btrfs_root *root,
> if (IS_ERR(inode))
> return 0;
>
> + if (block_group->flags & BTRFS_BLOCK_GROUP_DATA)
> + down_write(&root->fs_info->data_rwsem);
> +
> ret = __btrfs_write_out_cache(root, inode, ctl, block_group, trans,
> path, block_group->key.objectid);
> if (ret) {
> @@ -1111,6 +1142,9 @@ int btrfs_write_out_cache(struct btrfs_root *root,
> #endif
> }
>
> + if (block_group->flags & BTRFS_BLOCK_GROUP_DATA)
> + up_write(&root->fs_info->data_rwsem);
> +
> iput(inode);
> return ret;
> }
> diff --git a/fs/btrfs/inode.c b/fs/btrfs/inode.c
> index f1a7744..8172ca6 100644
> --- a/fs/btrfs/inode.c
> +++ b/fs/btrfs/inode.c
> @@ -592,6 +592,28 @@ free_pages_out:
> goto out;
> }
>
> +static void btrfs_unpin_data_extent(struct btrfs_root *root, u64 start,
> + u64 len)
> +{
> + struct btrfs_block_group_cache *cache;
> +
> + cache = btrfs_lookup_block_group(root->fs_info, start);
> + BUG_ON(!cache);
> + clear_extent_dirty(&cache->pinned_extents, start, start + len - 1,
> + GFP_NOFS);
> + btrfs_put_block_group(cache);
> +}
> +
> +/* it is not used for free space cache file */
> +static void btrfs_free_reserved_data_extent(struct btrfs_root *root, u64
> start,
> + u64 len)
> +{
> + down_read(&root->fs_info->data_rwsem);
> + btrfs_unpin_data_extent(root, start, len);
> + btrfs_free_reserved_extent(root, start, len);
> + up_read(&root->fs_info->data_rwsem);
> +}
> +
> /*
> * phase two of compressed writeback. This is the ordered portion
> * of the code, which only gets called in the order the work was
> @@ -666,7 +688,7 @@ retry:
> ret = btrfs_reserve_extent(root,
> async_extent->compressed_size,
> async_extent->compressed_size,
> - 0, alloc_hint, &ins, 1);
> + 0, alloc_hint, &ins, 1, true);
> if (ret) {
> int i;
>
> @@ -767,7 +789,7 @@ retry:
> out:
> return ret;
> out_free_reserve:
> - btrfs_free_reserved_extent(root, ins.objectid, ins.offset);
> + btrfs_free_reserved_data_extent(root, ins.objectid, ins.offset);
> out_free:
> extent_clear_unlock_delalloc(inode, async_extent->start,
> async_extent->start +
> @@ -889,7 +911,7 @@ static noinline int cow_file_range(struct inode *inode,
> cur_alloc_size = disk_num_bytes;
> ret = btrfs_reserve_extent(root, cur_alloc_size,
> root->sectorsize, 0, alloc_hint,
> - &ins, 1);
> + &ins, 1, true);
> if (ret < 0)
> goto out_unlock;
>
> @@ -967,6 +989,7 @@ out:
> return ret;
>
> out_reserve:
> + btrfs_unpin_data_extent(root, ins.objectid, ins.offset);
> btrfs_free_reserved_extent(root, ins.objectid, ins.offset);
> out_unlock:
> extent_clear_unlock_delalloc(inode, start, end, locked_page,
> @@ -2647,6 +2670,9 @@ static int btrfs_finish_ordered_io(struct
> btrfs_ordered_extent *ordered_extent)
> logical_len, logical_len,
> compress_type, 0, 0,
> BTRFS_FILE_EXTENT_REG);
> + BUG_ON(nolock);
> + btrfs_unpin_data_extent(root, ordered_extent->start,
> + ordered_extent->disk_len);
> }
> unpin_extent_cache(&BTRFS_I(inode)->extent_tree,
> ordered_extent->file_offset, ordered_extent->len,
> @@ -2698,8 +2724,9 @@ out:
> if ((ret || !logical_len) &&
> !test_bit(BTRFS_ORDERED_NOCOW, &ordered_extent->flags) &&
> !test_bit(BTRFS_ORDERED_PREALLOC, &ordered_extent->flags))
> - btrfs_free_reserved_extent(root, ordered_extent->start,
> - ordered_extent->disk_len);
> + btrfs_free_reserved_data_extent(root,
> + ordered_extent->start,
> +
> ordered_extent->disk_len);
> }
>
>
> @@ -6342,7 +6369,7 @@ static struct extent_map
> *btrfs_new_extent_direct(struct inode *inode,
>
> alloc_hint = get_extent_allocation_hint(inode, start, len);
> ret = btrfs_reserve_extent(root, len, root->sectorsize, 0,
> - alloc_hint, &ins, 1);
> + alloc_hint, &ins, 1, true);
> if (ret)
> return ERR_PTR(ret);
>
> @@ -6356,6 +6383,7 @@ static struct extent_map
> *btrfs_new_extent_direct(struct inode *inode,
> ret = btrfs_add_ordered_extent_dio(inode, start, ins.objectid,
> ins.offset, ins.offset, 0);
> if (ret) {
> + btrfs_unpin_data_extent(root, ins.objectid, ins.offset);
> btrfs_free_reserved_extent(root, ins.objectid, ins.offset);
> free_extent_map(em);
> return ERR_PTR(ret);
> @@ -8507,7 +8535,7 @@ static int __btrfs_prealloc_file_range(struct inode
> *inode, int mode,
> cur_bytes = min(num_bytes, 256ULL * 1024 * 1024);
> cur_bytes = max(cur_bytes, min_size);
> ret = btrfs_reserve_extent(root, cur_bytes, min_size, 0,
> - *alloc_hint, &ins, 1);
> + *alloc_hint, &ins, 1, false);
> if (ret) {
> if (own_trans)
> btrfs_end_transaction(trans, root);
> --
> 1.8.3.1
>
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