btrfs: remove the extent_buffer lookup in btree block checksumming

The checksumming of btree blocks always operates on the entire
extent_buffer, and because btree blocks are always allocated contiguously
on disk they are never split by btrfs_submit_bio.

Simplify the checksumming code by finding the extent_buffer in the
btrfs_bio private data instead of trying to search through the bio_vec.

Reviewed-by: Johannes Thumshirn <johannes.thumshirn@wdc.com>
Reviewed-by: Qu Wenruo <wqu@suse.com>
Reviewed-by: Josef Bacik <josef@toxicpanda.com>
Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>

diff --git a/fs/btrfs/disk-io.c b/fs/btrfs/disk-io.c
index db04a95..384c811 100644 (file)
--- a/fs/btrfs/disk-io.c
+++ b/fs/btrfs/disk-io.c
@@ -254,12 +254,34 @@ int btrfs_read_extent_buffer(struct extent_buffer *eb,
        return ret;
 }
 
-static int csum_one_extent_buffer(struct extent_buffer *eb)
+/*
+ * Checksum a dirty tree block before IO.
+ */
+blk_status_t btree_csum_one_bio(struct btrfs_bio *bbio)
 {
+       struct extent_buffer *eb = bbio->private;
        struct btrfs_fs_info *fs_info = eb->fs_info;
+       u64 found_start = btrfs_header_bytenr(eb);
        u8 result[BTRFS_CSUM_SIZE];
        int ret;
 
+       /* Btree blocks are always contiguous on disk. */
+       if (WARN_ON_ONCE(bbio->file_offset != eb->start))
+               return BLK_STS_IOERR;
+       if (WARN_ON_ONCE(bbio->bio.bi_iter.bi_size != eb->len))
+               return BLK_STS_IOERR;
+
+       if (test_bit(EXTENT_BUFFER_NO_CHECK, &eb->bflags)) {
+               WARN_ON_ONCE(found_start != 0);
+               return BLK_STS_OK;
+       }
+
+       if (WARN_ON_ONCE(found_start != eb->start))
+               return BLK_STS_IOERR;
+       if (WARN_ON(!btrfs_page_test_uptodate(fs_info, eb->pages[0], eb->start,
+                                             eb->len)))
+               return BLK_STS_IOERR;
+
        ASSERT(memcmp_extent_buffer(eb, fs_info->fs_devices->metadata_uuid,
                                    offsetof(struct btrfs_header, fsid),
                                    BTRFS_FSID_SIZE) == 0);
@@ -286,8 +308,7 @@ static int csum_one_extent_buffer(struct extent_buffer *eb)
                goto error;
        }
        write_extent_buffer(eb, result, 0, fs_info->csum_size);
-
-       return 0;
+       return BLK_STS_OK;
 
 error:
        btrfs_print_tree(eb, 0);
@@ -301,99 +322,6 @@ error:
         */
        WARN_ON(IS_ENABLED(CONFIG_BTRFS_DEBUG) ||
                btrfs_header_owner(eb) == BTRFS_TREE_LOG_OBJECTID);
-       return ret;
-}
-
-/* Checksum all dirty extent buffers in one bio_vec */
-static int csum_dirty_subpage_buffers(struct btrfs_fs_info *fs_info,
-                                     struct bio_vec *bvec)
-{
-       struct page *page = bvec->bv_page;
-       u64 bvec_start = page_offset(page) + bvec->bv_offset;
-       u64 cur;
-       int ret = 0;
-
-       for (cur = bvec_start; cur < bvec_start + bvec->bv_len;
-            cur += fs_info->nodesize) {
-               struct extent_buffer *eb;
-               bool uptodate;
-
-               eb = find_extent_buffer(fs_info, cur);
-               uptodate = btrfs_subpage_test_uptodate(fs_info, page, cur,
-                                                      fs_info->nodesize);
-
-               /* A dirty eb shouldn't disappear from buffer_radix */
-               if (WARN_ON(!eb))
-                       return -EUCLEAN;
-
-               if (WARN_ON(cur != btrfs_header_bytenr(eb))) {
-                       free_extent_buffer(eb);
-                       return -EUCLEAN;
-               }
-               if (WARN_ON(!uptodate)) {
-                       free_extent_buffer(eb);
-                       return -EUCLEAN;
-               }
-
-               ret = csum_one_extent_buffer(eb);
-               free_extent_buffer(eb);
-               if (ret < 0)
-                       return ret;
-       }
-       return ret;
-}
-
-/*
- * Checksum a dirty tree block before IO.  This has extra checks to make sure
- * we only fill in the checksum field in the first page of a multi-page block.
- * For subpage extent buffers we need bvec to also read the offset in the page.
- */
-static int csum_dirty_buffer(struct btrfs_fs_info *fs_info, struct bio_vec *bvec)
-{
-       struct page *page = bvec->bv_page;
-       u64 start = page_offset(page);
-       u64 found_start;
-       struct extent_buffer *eb;
-
-       if (fs_info->nodesize < PAGE_SIZE)
-               return csum_dirty_subpage_buffers(fs_info, bvec);
-
-       eb = (struct extent_buffer *)page->private;
-       if (page != eb->pages[0])
-               return 0;
-
-       found_start = btrfs_header_bytenr(eb);
-
-       if (test_bit(EXTENT_BUFFER_NO_CHECK, &eb->bflags)) {
-               WARN_ON(found_start != 0);
-               return 0;
-       }
-
-       /*
-        * Please do not consolidate these warnings into a single if.
-        * It is useful to know what went wrong.
-        */
-       if (WARN_ON(found_start != start))
-               return -EUCLEAN;
-       if (WARN_ON(!PageUptodate(page)))
-               return -EUCLEAN;
-
-       return csum_one_extent_buffer(eb);
-}
-
-blk_status_t btree_csum_one_bio(struct btrfs_bio *bbio)
-{
-       struct btrfs_fs_info *fs_info = bbio->inode->root->fs_info;
-       struct bvec_iter iter;
-       struct bio_vec bv;
-       int ret = 0;
-
-       bio_for_each_segment(bv, &bbio->bio, iter) {
-               ret = csum_dirty_buffer(fs_info, &bv);
-               if (ret)
-                       break;
-       }
-
        return errno_to_blk_status(ret);
 }