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Qu Wenruo authored
Due to the complex nature of btrfs extent tree, when we want to iterate all backrefs of one extent, this involves quite a lot of work, like searching the EXTENT_ITEM/METADATA_ITEM, iteration through inline and keyed backrefs. Normally this would result in a complex code, something like: btrfs_search_slot() /* Ensure we are at EXTENT_ITEM/METADATA_ITEM */ while (1) { /* Loop for extent tree items */ while (ptr < end) { /* Loop for inlined items */ /* Real work here */ } next: ret = btrfs_next_item() /* Ensure we're still at keyed item for specified bytenr */ } The idea of btrfs_backref_iter is to avoid such complex and hard to read code structure, but something like the following: iter = btrfs_backref_iter_alloc(); ret = btrfs_backref_iter_start(iter, bytenr); if (ret < 0) goto out; for (; ; ret = btrfs_backref_iter_next(iter)) { /* Real work here */ } out: btrfs_backref_iter_free(iter); This patch is just the skeleton + btrfs_backref_iter_start() code. Reviewed-by:
Johannes Thumshirn <johannes.thumshirn@wdc.com> Reviewed-by:
Josef Bacik <josef@toxicpanda.com> Signed-off-by:
Qu Wenruo <wqu@suse.com> Reviewed-by:
David Sterba <dsterba@suse.com> Signed-off-by:
David Sterba <dsterba@suse.com>
a37f232b