Introduce functions to remove reserved ranges for later btrfs-convert rework.
The reserved ranges includes: 1. [0,1M) 2. [btrfs_sb_offset(1), +BTRFS_STRIP_LEN) 3. [btrfs_sb_offset(2), +BTRFS_STRIP_LEN) Signed-off-by: Qu Wenruo <[email protected]> --- utils.c | 115 ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 115 insertions(+) diff --git a/utils.c b/utils.c index 60235d8..5ab5ede 100644 --- a/utils.c +++ b/utils.c @@ -177,6 +177,121 @@ int test_uuid_unique(char *fs_uuid) } /* + * Remove one reserve range from given cache tree + * if min_stripe_size is non-zero, it will ensure for split case, + * all its split cache extent is no smaller than @min_strip_size / 2. + * + */ +static int wipe_one_reserved_range(struct cache_tree *tree, + u64 start, u64 len, u64 min_stripe_size, + int ensure_size) +{ + struct cache_extent *cache; + int ret; + + /* The logical here is simplified to handle special cases only */ + BUG_ON(min_stripe_size < len * 2 || + min_stripe_size / 2 < BTRFS_STRIPE_LEN); + + /* Also, wipe range should already be aligned */ + BUG_ON(start != round_down(start, BTRFS_STRIPE_LEN) || + start + len != round_up(start + len, BTRFS_STRIPE_LEN)); + + min_stripe_size /= 2; + + cache = lookup_cache_extent(tree, start, len); + if (!cache) + return 0; + + if (start <= cache->start) { + /* + * |--------cache---------| + * |-wipe-| + */ + BUG_ON(start + len <= cache->start); + + /* + * The wipe size is smaller than min_stripe_size / 2, + * so the result length should still meet min_stripe_size + * And no need to do alignment + */ + cache->size -= (start + len - cache->start); + if (cache->size == 0) { + remove_cache_extent(tree, cache); + free(cache); + return 0; + } + + BUG_ON(ensure_size && cache->size < min_stripe_size); + + cache->start = start + len; + return 0; + } else if (start > cache->start && start + len < cache->start + + cache->size) { + /* + * |-------cache-----| + * |-wipe-| + */ + u64 old_len = cache->size; + u64 insert_start = start + len; + u64 insert_len; + + cache->size = start - cache->start; + if (ensure_size) + cache->size = max(cache->size, min_stripe_size); + cache->start = start - cache->size; + + /* And insert the new one */ + insert_len = old_len - start - len; + if (ensure_size) + insert_len = max(insert_len, min_stripe_size); + + ret = add_merge_cache_extent(tree, insert_start, insert_len); + return ret; + } else { + /* + * |----cache-----| + * |--wipe-| + * Wipe len should be small enough and no need to expand the + * remaining extent + */ + cache->size = start - cache->start; + BUG_ON(ensure_size && cache->size < min_stripe_size); + return 0; + } +} + +/* + * Remove reserved ranges from given cache_tree + * + * It will remove the following ranges + * 1) 0~1M + * 2) 2nd superblock, +64K(make sure chunks are 64K aligned) + * 3) 3rd superblock, +64K + * + * @min_stripe must be given for safety check + * and if @ensure_size is given, it will ensure affected cache_extent will be + * larger than min_stripe_size + */ +static int wipe_reserved_ranges(struct cache_tree *tree, u64 min_stripe_size, + int ensure_size) +{ + int ret; + + ret = wipe_one_reserved_range(tree, 0, 1024 * 1024, min_stripe_size, + ensure_size); + if (ret < 0) + return ret; + ret = wipe_one_reserved_range(tree, btrfs_sb_offset(1), BTRFS_STRIPE_LEN, + min_stripe_size, ensure_size); + if (ret < 0) + return ret; + ret = wipe_one_reserved_range(tree, btrfs_sb_offset(2), BTRFS_STRIPE_LEN, + min_stripe_size, ensure_size); + return ret; +} + +/* * @fs_uuid - if NULL, generates a UUID, returns back the new filesystem UUID */ int make_btrfs(int fd, struct btrfs_mkfs_config *cfg) -- 2.6.2 -- To unsubscribe from this list: send the line "unsubscribe linux-btrfs" in the body of a message to [email protected] More majordomo info at http://vger.kernel.org/majordomo-info.html
