3 files changed, 19 insertions, 12 deletions

diff --git a/fs/btrfs/compression.c b/fs/btrfs/compression.c
index a8e551ca8798..92291f266324 100644
--- a/fs/btrfs/compression.c
+++ b/fs/btrfs/compression.c
@@ -57,12 +57,14 @@ static int check_compressed_csum(struct btrfs_inode *inode,
                                  struct compressed_bio *cb,
                                  u64 disk_start)
 {
+        struct btrfs_fs_info *fs_info = inode->root->fs_info;
+        const u16 csum_size = btrfs_super_csum_size(fs_info->super_copy);
         int ret;
         struct page *page;
         unsigned long i;
         char *kaddr;
         u32 csum;
-        u32 *cb_sum = &cb->sums;
+        u8 *cb_sum = cb->sums;
 
         if (inode->flags & BTRFS_INODE_NODATASUM)
                 return 0;
@@ -76,13 +78,13 @@ static int check_compressed_csum(struct btrfs_inode *inode,
                 btrfs_csum_final(csum, (u8 *)&csum);
                 kunmap_atomic(kaddr);
 
-                if (csum != *cb_sum) {
+                if (memcmp(&csum, cb_sum, csum_size)) {
                         btrfs_print_data_csum_error(inode, disk_start, csum,
-                                        *cb_sum, cb->mirror_num);
+                                        *(u32 *)cb_sum, cb->mirror_num);
                         ret = -EIO;
                         goto fail;
                 }
-                cb_sum++;
+                cb_sum += csum_size;
 
         }
         ret = 0;
@@ -536,7 +538,8 @@ blk_status_t btrfs_submit_compressed_read(struct inode *inode, struct bio *bio,
         struct extent_map *em;
         blk_status_t ret = BLK_STS_RESOURCE;
         int faili = 0;
-        u32 *sums;
+        const u16 csum_size = btrfs_super_csum_size(fs_info->super_copy);
+        u8 *sums;
 
         em_tree = &BTRFS_I(inode)->extent_tree;
 
@@ -558,7 +561,7 @@ blk_status_t btrfs_submit_compressed_read(struct inode *inode, struct bio *bio,
         cb->errors = 0;
         cb->inode = inode;
         cb->mirror_num = mirror_num;
-        sums = &cb->sums;
+        sums = cb->sums;
 
         cb->start = em->orig_start;
         em_len = em->len;
@@ -617,6 +620,8 @@ blk_status_t btrfs_submit_compressed_read(struct inode *inode, struct bio *bio,
                 page->mapping = NULL;
                 if (submit || bio_add_page(comp_bio, page, PAGE_SIZE, 0) <
                     PAGE_SIZE) {
+                        unsigned int nr_sectors;
+
                         ret = btrfs_bio_wq_end_io(fs_info, comp_bio,
                                                   BTRFS_WQ_ENDIO_DATA);
                         BUG_ON(ret); /* -ENOMEM */
@@ -631,11 +636,13 @@ blk_status_t btrfs_submit_compressed_read(struct inode *inode, struct bio *bio,
 
                         if (!(BTRFS_I(inode)->flags & BTRFS_INODE_NODATASUM)) {
                                 ret = btrfs_lookup_bio_sums(inode, comp_bio,
-                                                            (u8 *)sums);
+                                                            sums);
                                 BUG_ON(ret); /* -ENOMEM */
                         }
-                        sums += DIV_ROUND_UP(comp_bio->bi_iter.bi_size,
-                                             fs_info->sectorsize);
+
+                        nr_sectors = DIV_ROUND_UP(comp_bio->bi_iter.bi_size,
+                                                  fs_info->sectorsize);
+                        sums += csum_size * nr_sectors;
 
                         ret = btrfs_map_bio(fs_info, comp_bio, mirror_num, 0);
                         if (ret) {
@@ -657,7 +664,7 @@ blk_status_t btrfs_submit_compressed_read(struct inode *inode, struct bio *bio,
         BUG_ON(ret); /* -ENOMEM */
 
         if (!(BTRFS_I(inode)->flags & BTRFS_INODE_NODATASUM)) {
-                ret = btrfs_lookup_bio_sums(inode, comp_bio, (u8 *) sums);
+                ret = btrfs_lookup_bio_sums(inode, comp_bio, sums);
                 BUG_ON(ret); /* -ENOMEM */
         }
 
diff --git a/fs/btrfs/compression.h b/fs/btrfs/compression.h
index 9976fe0f7526..191e5f4e3523 100644
--- a/fs/btrfs/compression.h
+++ b/fs/btrfs/compression.h
@@ -61,7 +61,7 @@ struct compressed_bio {
          * the start of a variable length array of checksums only
          * used by reads
          */
-        u32 sums;
+        u8 sums[];
 };
 
 static inline unsigned int btrfs_compress_type(unsigned int type_level)
diff --git a/fs/btrfs/file-item.c b/fs/btrfs/file-item.c
index 0464dd4c0579..de89fd1310a6 100644
--- a/fs/btrfs/file-item.c
+++ b/fs/btrfs/file-item.c
@@ -186,7 +186,7 @@ static blk_status_t __btrfs_lookup_bio_sums(struct inode *inode, struct bio *bio
                 }
                 csum = btrfs_bio->csum;
         } else {
-                csum = (u8 *)dst;
+                csum = dst;
         }
 
         if (bio->bi_iter.bi_size > PAGE_SIZE * 8)