From c04e61b5e41b0e8ace4aa4b67685fbe68ac37a46 Mon Sep 17 00:00:00 2001 From: Liu Bo Date: Fri, 5 Jan 2018 12:51:11 -0700 Subject: Btrfs: move extent map specific code to extent_map.c These helpers are extent map specific, move them to extent_map.c. Signed-off-by: Liu Bo Reviewed-by: Josef Bacik Signed-off-by: David Sterba --- fs/btrfs/extent_map.c | 125 ++++++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 125 insertions(+) (limited to 'fs/btrfs/extent_map.c') diff --git a/fs/btrfs/extent_map.c b/fs/btrfs/extent_map.c index 2e348fb0b280..6fe8b14e11cf 100644 --- a/fs/btrfs/extent_map.c +++ b/fs/btrfs/extent_map.c @@ -454,3 +454,128 @@ void replace_extent_mapping(struct extent_map_tree *tree, setup_extent_mapping(tree, new, modified); } + +static struct extent_map *next_extent_map(struct extent_map *em) +{ + struct rb_node *next; + + next = rb_next(&em->rb_node); + if (!next) + return NULL; + return container_of(next, struct extent_map, rb_node); +} + +static struct extent_map *prev_extent_map(struct extent_map *em) +{ + struct rb_node *prev; + + prev = rb_prev(&em->rb_node); + if (!prev) + return NULL; + return container_of(prev, struct extent_map, rb_node); +} + +/* helper for btfs_get_extent. Given an existing extent in the tree, + * the existing extent is the nearest extent to map_start, + * and an extent that you want to insert, deal with overlap and insert + * the best fitted new extent into the tree. + */ +static int merge_extent_mapping(struct extent_map_tree *em_tree, + struct extent_map *existing, + struct extent_map *em, + u64 map_start) +{ + struct extent_map *prev; + struct extent_map *next; + u64 start; + u64 end; + u64 start_diff; + + BUG_ON(map_start < em->start || map_start >= extent_map_end(em)); + + if (existing->start > map_start) { + next = existing; + prev = prev_extent_map(next); + } else { + prev = existing; + next = next_extent_map(prev); + } + + start = prev ? extent_map_end(prev) : em->start; + start = max_t(u64, start, em->start); + end = next ? next->start : extent_map_end(em); + end = min_t(u64, end, extent_map_end(em)); + start_diff = start - em->start; + em->start = start; + em->len = end - start; + if (em->block_start < EXTENT_MAP_LAST_BYTE && + !test_bit(EXTENT_FLAG_COMPRESSED, &em->flags)) { + em->block_start += start_diff; + em->block_len = em->len; + } + return add_extent_mapping(em_tree, em, 0); +} + +/** + * btrfs_add_extent_mapping - add extent mapping into em_tree + * @em_tree - the extent tree into which we want to insert the extent mapping + * @em_in - extent we are inserting + * @start - start of the logical range btrfs_get_extent() is requesting + * @len - length of the logical range btrfs_get_extent() is requesting + * + * Note that @em_in's range may be different from [start, start+len), + * but they must be overlapped. + * + * Insert @em_in into @em_tree. In case there is an overlapping range, handle + * the -EEXIST by either: + * a) Returning the existing extent in @em_in if @start is within the + * existing em. + * b) Merge the existing extent with @em_in passed in. + * + * Return 0 on success, otherwise -EEXIST. + * + */ +int btrfs_add_extent_mapping(struct extent_map_tree *em_tree, + struct extent_map **em_in, u64 start, u64 len) +{ + int ret; + struct extent_map *em = *em_in; + + ret = add_extent_mapping(em_tree, em, 0); + /* it is possible that someone inserted the extent into the tree + * while we had the lock dropped. It is also possible that + * an overlapping map exists in the tree + */ + if (ret == -EEXIST) { + struct extent_map *existing; + + ret = 0; + + existing = search_extent_mapping(em_tree, start, len); + /* + * existing will always be non-NULL, since there must be + * extent causing the -EEXIST. + */ + if (start >= existing->start && + start < extent_map_end(existing)) { + free_extent_map(em); + *em_in = existing; + ret = 0; + } else { + /* + * The existing extent map is the one nearest to + * the [start, start + len) range which overlaps + */ + ret = merge_extent_mapping(em_tree, existing, + em, start); + free_extent_map(existing); + if (ret) { + free_extent_map(em); + *em_in = NULL; + } + } + } + + ASSERT(ret == 0 || ret == -EEXIST); + return ret; +} -- cgit v1.2.1