On 22.05.2018 10:29, Qu Wenruo wrote: > Introduce a small helper, btrfs_add_unused_bgs(), to accquire needed
This function name sounds a bit awkard, mainly because you use the plural form. How about btrfs_mark_bg_unused() ? The name seems more unambiguous. > locks and add a block group to unused_bgs list. > > No functional modification, and only 3 callers are involved. > > Signed-off-by: Qu Wenruo <w...@suse.com> > --- > This patch should provide the basis for later block group auto-removal > to get more info (mostly transid) to determine should one block group > being removed in current trans. > --- > fs/btrfs/ctree.h | 1 + > fs/btrfs/extent-tree.c | 35 ++++++++++++++++------------------- > fs/btrfs/scrub.c | 9 +-------- > 3 files changed, 18 insertions(+), 27 deletions(-) > > diff --git a/fs/btrfs/ctree.h b/fs/btrfs/ctree.h > index bbb358143ded..701a52034ec6 100644 > --- a/fs/btrfs/ctree.h > +++ b/fs/btrfs/ctree.h > @@ -2827,6 +2827,7 @@ void check_system_chunk(struct btrfs_trans_handle > *trans, > struct btrfs_fs_info *fs_info, const u64 type); > u64 add_new_free_space(struct btrfs_block_group_cache *block_group, > u64 start, u64 end); > +void btrfs_add_unused_bgs(struct btrfs_block_group_cache *bg); > > /* ctree.c */ > int btrfs_bin_search(struct extent_buffer *eb, const struct btrfs_key *key, > diff --git a/fs/btrfs/extent-tree.c b/fs/btrfs/extent-tree.c > index ccf2690f7ca1..484c9d11e5b6 100644 > --- a/fs/btrfs/extent-tree.c > +++ b/fs/btrfs/extent-tree.c > @@ -6312,16 +6312,8 @@ static int update_block_group(struct > btrfs_trans_handle *trans, > * dirty list to avoid races between cleaner kthread and space > * cache writeout. > */ > - if (!alloc && old_val == 0) { > - spin_lock(&info->unused_bgs_lock); > - if (list_empty(&cache->bg_list)) { > - btrfs_get_block_group(cache); > - trace_btrfs_add_unused_block_group(cache); > - list_add_tail(&cache->bg_list, > - &info->unused_bgs); > - } > - spin_unlock(&info->unused_bgs_lock); > - } > + if (!alloc && old_val == 0) > + btrfs_add_unused_bgs(cache); > > btrfs_put_block_group(cache); > total -= num_bytes; > @@ -10144,15 +10136,7 @@ int btrfs_read_block_groups(struct btrfs_fs_info > *info) > if (btrfs_chunk_readonly(info, cache->key.objectid)) { > inc_block_group_ro(cache, 1); > } else if (btrfs_block_group_used(&cache->item) == 0) { > - spin_lock(&info->unused_bgs_lock); > - /* Should always be true but just in case. */ > - if (list_empty(&cache->bg_list)) { > - btrfs_get_block_group(cache); > - trace_btrfs_add_unused_block_group(cache); > - list_add_tail(&cache->bg_list, > - &info->unused_bgs); > - } > - spin_unlock(&info->unused_bgs_lock); > + btrfs_add_unused_bgs(cache); > } > } > > @@ -11071,3 +11055,16 @@ void btrfs_wait_for_snapshot_creation(struct > btrfs_root *root) > !atomic_read(&root->will_be_snapshotted)); > } > } > + > +void btrfs_add_unused_bgs(struct btrfs_block_group_cache *bg) > +{ > + struct btrfs_fs_info *fs_info = bg->fs_info; > + > + spin_lock(&fs_info->unused_bgs_lock); > + if (list_empty(&bg->bg_list)) { Given the comment in btrfs_read_block_groups: /* Should always be true but just in case. */ How about you make it ASSERT(list_empty(&bg->bg_list)); /* code to add the bg */ So right now either : a) The comment is bogus and it is indeed required to check if this bg has already been marked unused. or b) The comment is correct and it's in fact a bug to try and mark a bg as unused twice. > + btrfs_get_block_group(bg); > + trace_btrfs_add_unused_block_group(bg); > + list_add_tail(&bg->bg_list, &fs_info->unused_bgs); > + } > + spin_unlock(&fs_info->unused_bgs_lock); > +} > diff --git a/fs/btrfs/scrub.c b/fs/btrfs/scrub.c > index a59005862010..1044ab2fc71c 100644 > --- a/fs/btrfs/scrub.c > +++ b/fs/btrfs/scrub.c > @@ -3981,14 +3981,7 @@ int scrub_enumerate_chunks(struct scrub_ctx *sctx, > if (!cache->removed && !cache->ro && cache->reserved == 0 && > btrfs_block_group_used(&cache->item) == 0) { > spin_unlock(&cache->lock); > - spin_lock(&fs_info->unused_bgs_lock); > - if (list_empty(&cache->bg_list)) { > - btrfs_get_block_group(cache); > - trace_btrfs_add_unused_block_group(cache); > - list_add_tail(&cache->bg_list, > - &fs_info->unused_bgs); > - } > - spin_unlock(&fs_info->unused_bgs_lock); > + btrfs_add_unused_bgs(cache); > } else { > spin_unlock(&cache->lock); > } > -- 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