From 1776ad172e1ff09d4aa57daac74c56b4e1b0c636 Mon Sep 17 00:00:00 2001 From: Nikolay Borisov Date: Tue, 19 Nov 2019 14:05:53 +0200 Subject: [PATCH] btrfs: Refactor btrfs_rmap_block to improve readability Move variables to appropriate scope. Remove last BUG_ON in the function and rework error handling accordingly. Make the duplicate detection code more straightforward. Use in_range macro. And give variables more descriptive name by explicitly distinguishing between IO stripe size (size recorded in the chunk item) and data stripe size (the size of an actual stripe, constituting a logical chunk/block group). Signed-off-by: Nikolay Borisov Reviewed-by: David Sterba Signed-off-by: David Sterba --- fs/btrfs/block-group.c | 55 ++++++++++++++++++++++++++++++-------------------- 1 file changed, 33 insertions(+), 22 deletions(-) diff --git a/fs/btrfs/block-group.c b/fs/btrfs/block-group.c index 00cb402..1485158 100644 --- a/fs/btrfs/block-group.c +++ b/fs/btrfs/block-group.c @@ -1582,34 +1582,43 @@ int btrfs_rmap_block(struct btrfs_fs_info *fs_info, u64 chunk_start, struct map_lookup *map; u64 *buf; u64 bytenr; - u64 length; - u64 stripe_nr; - u64 rmap_len; - int i, j, nr = 0; + u64 data_stripe_length; + u64 io_stripe_size; + int i, nr = 0; + int ret = 0; em = btrfs_get_chunk_map(fs_info, chunk_start, 1); if (IS_ERR(em)) return -EIO; map = em->map_lookup; - length = em->len; - rmap_len = map->stripe_len; + data_stripe_length = em->len; + io_stripe_size = map->stripe_len; if (map->type & BTRFS_BLOCK_GROUP_RAID10) - length = div_u64(length, map->num_stripes / map->sub_stripes); + data_stripe_length = div_u64(data_stripe_length, + map->num_stripes / map->sub_stripes); else if (map->type & BTRFS_BLOCK_GROUP_RAID0) - length = div_u64(length, map->num_stripes); + data_stripe_length = div_u64(data_stripe_length, map->num_stripes); else if (map->type & BTRFS_BLOCK_GROUP_RAID56_MASK) { - length = div_u64(length, nr_data_stripes(map)); - rmap_len = map->stripe_len * nr_data_stripes(map); + data_stripe_length = div_u64(data_stripe_length, + nr_data_stripes(map)); + io_stripe_size = map->stripe_len * nr_data_stripes(map); } buf = kcalloc(map->num_stripes, sizeof(u64), GFP_NOFS); - BUG_ON(!buf); /* -ENOMEM */ + if (!buf) { + ret = -ENOMEM; + goto out; + } for (i = 0; i < map->num_stripes; i++) { - if (map->stripes[i].physical > physical || - map->stripes[i].physical + length <= physical) + bool already_inserted = false; + u64 stripe_nr; + int j; + + if (!in_range(physical, map->stripes[i].physical, + data_stripe_length)) continue; stripe_nr = physical - map->stripes[i].physical; @@ -1627,24 +1636,26 @@ int btrfs_rmap_block(struct btrfs_fs_info *fs_info, u64 chunk_start, * instead of map->stripe_len */ - bytenr = chunk_start + stripe_nr * rmap_len; - WARN_ON(nr >= map->num_stripes); + bytenr = chunk_start + stripe_nr * io_stripe_size; + + /* Ensure we don't add duplicate addresses */ for (j = 0; j < nr; j++) { - if (buf[j] == bytenr) + if (buf[j] == bytenr) { + already_inserted = true; break; + } } - if (j == nr) { - WARN_ON(nr >= map->num_stripes); + + if (!already_inserted) buf[nr++] = bytenr; - } } *logical = buf; *naddrs = nr; - *stripe_len = rmap_len; - + *stripe_len = io_stripe_size; +out: free_extent_map(em); - return 0; + return ret; } static int exclude_super_stripes(struct btrfs_block_group *cache) -- 2.7.4