[PATCH 1/2] btrfs: cleanup the argument list of scrub_chunk()

Qu Wenruo
2021-12-15T07:00:25Z

The argument list of scrub_chunk() has the following problems:

- Duplicated @chunk_offset
It is the same as btrfs_block_group::start.

- Confusing @length
The most instinctive guess is chunk length, and one may want to delete
it, but the truth is, it's device extent length.

Fix this by:

- Remove @chunk_offset
Use btrfs_block_group::start instead.

- Rename @length to @dev_ext_len
Also rename the caller to remove the ambiguous naming.

- Rename @cache to @bg
The "_cache" suffix for btrfs_block_group is removed for a while.

Signed-off-by: Qu Wenruo <wqu@suse.com>
---
fs/btrfs/scrub.c | 38 +++++++++++++++++++-------------------
1 file changed, 19 insertions(+), 19 deletions(-)

diff --git a/fs/btrfs/scrub.c b/fs/btrfs/scrub.c
index 5e59e27e6bcd..ffbaf6fbf71c 100644
--- a/fs/btrfs/scrub.c
+++ b/fs/btrfs/scrub.c
@@ -3548,10 +3548,10 @@ static noinline_for_stack int scrub_stripe(struct scrub_ctx *sctx,
}

static noinline_for_stack int scrub_chunk(struct scrub_ctx *sctx,
+ struct btrfs_block_group *bg,
struct btrfs_device *scrub_dev,
- u64 chunk_offset, u64 length,
u64 dev_offset,
- struct btrfs_block_group *cache)
+ u64 dev_ext_len)
{
struct btrfs_fs_info *fs_info = sctx->fs_info;
struct extent_map_tree *map_tree = &fs_info->mapping_tree;
@@ -3561,7 +3561,7 @@ static noinline_for_stack int scrub_chunk(struct scrub_ctx *sctx,
int ret = 0;

read_lock(&map_tree->lock);
- em = lookup_extent_mapping(map_tree, chunk_offset, 1);
+ em = lookup_extent_mapping(map_tree, bg->start, bg->length);
read_unlock(&map_tree->lock);

if (!em) {
@@ -3569,26 +3569,24 @@ static noinline_for_stack int scrub_chunk(struct scrub_ctx *sctx,
* Might have been an unused block group deleted by the cleaner
* kthread or relocation.
*/
- spin_lock(&cache->lock);
- if (!cache->removed)
+ spin_lock(&bg->lock);
+ if (!bg->removed)
ret = -EINVAL;
- spin_unlock(&cache->lock);
+ spin_unlock(&bg->lock);

return ret;
}
-
- map = em->map_lookup;
- if (em->start != chunk_offset)
+ if (em->start != bg->start)
goto out;
-
- if (em->len < length)
+ if (em->len < dev_ext_len)
goto out;

+ map = em->map_lookup;
for (i = 0; i < map->num_stripes; ++i) {
if (map->stripes[i].dev->bdev == scrub_dev->bdev &&
map->stripes[i].physical == dev_offset) {
ret = scrub_stripe(sctx, map, scrub_dev, i,
- chunk_offset, length, cache);
+ bg->start, dev_ext_len, bg);
if (ret)
goto out;
}
@@ -3626,7 +3624,6 @@ int scrub_enumerate_chunks(struct scrub_ctx *sctx,
struct btrfs_path *path;
struct btrfs_fs_info *fs_info = sctx->fs_info;
struct btrfs_root *root = fs_info->dev_root;
- u64 length;
u64 chunk_offset;
int ret = 0;
int ro_set;
@@ -3650,6 +3647,8 @@ int scrub_enumerate_chunks(struct scrub_ctx *sctx,
key.type = BTRFS_DEV_EXTENT_KEY;

while (1) {
+ u64 dev_ext_len;
+
ret = btrfs_search_slot(NULL, root, &key, path, 0, 0);
if (ret < 0)
break;
@@ -3686,9 +3685,9 @@ int scrub_enumerate_chunks(struct scrub_ctx *sctx,
break;

dev_extent = btrfs_item_ptr(l, slot, struct btrfs_dev_extent);
- length = btrfs_dev_extent_length(l, dev_extent);
+ dev_ext_len = btrfs_dev_extent_length(l, dev_extent);

- if (found_key.offset + length <= start)
+ if (found_key.offset + dev_ext_len <= start)
goto skip;

chunk_offset = btrfs_dev_extent_chunk_offset(l, dev_extent);
@@ -3822,13 +3821,14 @@ int scrub_enumerate_chunks(struct scrub_ctx *sctx,

scrub_pause_off(fs_info);
down_write(&dev_replace->rwsem);
- dev_replace->cursor_right = found_key.offset + length;
+ dev_replace->cursor_right = found_key.offset + dev_ext_len;
dev_replace->cursor_left = found_key.offset;
dev_replace->item_needs_writeback = 1;
up_write(&dev_replace->rwsem);

- ret = scrub_chunk(sctx, scrub_dev, chunk_offset, length,
- found_key.offset, cache);
+ ASSERT(cache->start == chunk_offset);
+ ret = scrub_chunk(sctx, cache, scrub_dev, found_key.offset,
+ dev_ext_len);

/*
* flush, submit all pending read and write bios, afterwards
@@ -3909,7 +3909,7 @@ int scrub_enumerate_chunks(struct scrub_ctx *sctx,
break;
}
skip:
- key.offset = found_key.offset + length;
+ key.offset = found_key.offset + dev_ext_len;
btrfs_release_path(path);
}

--
2.34.1