From c39c2ddc67024979915c4df4e30da96a3e7619b0 Mon Sep 17 00:00:00 2001 From: Qu Wenruo Date: Thu, 13 Feb 2020 15:04:04 +0800 Subject: [PATCH] btrfs: backref: implement btrfs_backref_iter_next() This function will go to the next inline/keyed backref for btrfs_backref_iter infrastructure. Reviewed-by: Johannes Thumshirn Reviewed-by: Josef Bacik Signed-off-by: Qu Wenruo Reviewed-by: David Sterba Signed-off-by: David Sterba --- fs/btrfs/backref.c | 60 ++++++++++++++++++++++++++++++++++++++++++++++++++++++ fs/btrfs/backref.h | 34 +++++++++++++++++++++++++++++++ 2 files changed, 94 insertions(+) diff --git a/fs/btrfs/backref.c b/fs/btrfs/backref.c index a1bac1b..27f9a59 100644 --- a/fs/btrfs/backref.c +++ b/fs/btrfs/backref.c @@ -2405,3 +2405,63 @@ release: btrfs_backref_iter_release(iter); return ret; } + +/* + * Go to the next backref item of current bytenr, can be either inlined or + * keyed. + * + * Caller needs to check whether it's inline ref or not by iter->cur_key. + * + * Return 0 if we get next backref without problem. + * Return >0 if there is no extra backref for this bytenr. + * Return <0 if there is something wrong happened. + */ +int btrfs_backref_iter_next(struct btrfs_backref_iter *iter) +{ + struct extent_buffer *eb = btrfs_backref_get_eb(iter); + struct btrfs_path *path = iter->path; + struct btrfs_extent_inline_ref *iref; + int ret; + u32 size; + + if (btrfs_backref_iter_is_inline_ref(iter)) { + /* We're still inside the inline refs */ + ASSERT(iter->cur_ptr < iter->end_ptr); + + if (btrfs_backref_has_tree_block_info(iter)) { + /* First tree block info */ + size = sizeof(struct btrfs_tree_block_info); + } else { + /* Use inline ref type to determine the size */ + int type; + + iref = (struct btrfs_extent_inline_ref *) + ((unsigned long)iter->cur_ptr); + type = btrfs_extent_inline_ref_type(eb, iref); + + size = btrfs_extent_inline_ref_size(type); + } + iter->cur_ptr += size; + if (iter->cur_ptr < iter->end_ptr) + return 0; + + /* All inline items iterated, fall through */ + } + + /* We're at keyed items, there is no inline item, go to the next one */ + ret = btrfs_next_item(iter->fs_info->extent_root, iter->path); + if (ret) + return ret; + + btrfs_item_key_to_cpu(path->nodes[0], &iter->cur_key, path->slots[0]); + if (iter->cur_key.objectid != iter->bytenr || + (iter->cur_key.type != BTRFS_TREE_BLOCK_REF_KEY && + iter->cur_key.type != BTRFS_SHARED_BLOCK_REF_KEY)) + return 1; + iter->item_ptr = (u32)btrfs_item_ptr_offset(path->nodes[0], + path->slots[0]); + iter->cur_ptr = iter->item_ptr; + iter->end_ptr = iter->item_ptr + (u32)btrfs_item_size_nr(path->nodes[0], + path->slots[0]); + return 0; +} diff --git a/fs/btrfs/backref.h b/fs/btrfs/backref.h index 4ae37fa..46faf9b 100644 --- a/fs/btrfs/backref.h +++ b/fs/btrfs/backref.h @@ -104,8 +104,42 @@ static inline void btrfs_backref_iter_free(struct btrfs_backref_iter *iter) kfree(iter); } +static inline struct extent_buffer *btrfs_backref_get_eb( + struct btrfs_backref_iter *iter) +{ + if (!iter) + return NULL; + return iter->path->nodes[0]; +} + +/* + * For metadata with EXTENT_ITEM key (non-skinny) case, the first inline data + * is btrfs_tree_block_info, without a btrfs_extent_inline_ref header. + * + * This helper determines if that's the case. + */ +static inline bool btrfs_backref_has_tree_block_info( + struct btrfs_backref_iter *iter) +{ + if (iter->cur_key.type == BTRFS_EXTENT_ITEM_KEY && + iter->cur_ptr - iter->item_ptr == sizeof(struct btrfs_extent_item)) + return true; + return false; +} + int btrfs_backref_iter_start(struct btrfs_backref_iter *iter, u64 bytenr); +int btrfs_backref_iter_next(struct btrfs_backref_iter *iter); + +static inline bool btrfs_backref_iter_is_inline_ref( + struct btrfs_backref_iter *iter) +{ + if (iter->cur_key.type == BTRFS_EXTENT_ITEM_KEY || + iter->cur_key.type == BTRFS_METADATA_ITEM_KEY) + return true; + return false; +} + static inline void btrfs_backref_iter_release(struct btrfs_backref_iter *iter) { iter->bytenr = 0; -- 2.7.4