Btrfs: Handle data checksumming on bios that span multiple ordered extents

Data checksumming is done right before the bio is sent down the IO stack,
which means a single bio might span more than one ordered extent.  In
this case, the checksumming data is split between two ordered extents.

Signed-off-by: Chris Mason <chris.mason@oracle.com>

1 files changed, 39 insertions, 4 deletions

diff --git a/fs/btrfs/file-item.c b/fs/btrfs/file-item.c
index 345caf8ff516..e02f1e5acb0a 100644
--- a/fs/btrfs/file-item.c
+++ b/fs/btrfs/file-item.c
@@ -134,26 +134,53 @@ int btrfs_lookup_file_extent(struct btrfs_trans_handle *trans,
         return ret;
 }
 
-int btrfs_csum_one_bio(struct btrfs_root *root,
-                       struct bio *bio, struct btrfs_ordered_sum **sums_ret)
+int btrfs_csum_one_bio(struct btrfs_root *root, struct inode *inode,
+                       struct bio *bio)
 {
         struct btrfs_ordered_sum *sums;
         struct btrfs_sector_sum *sector_sum;
+        struct btrfs_ordered_extent *ordered;
         char *data;
         struct bio_vec *bvec = bio->bi_io_vec;
         int bio_index = 0;
+        unsigned long total_bytes = 0;
+        unsigned long this_sum_bytes = 0;
+        u64 offset;
 
         WARN_ON(bio->bi_vcnt <= 0);
         sums = kzalloc(btrfs_ordered_sum_size(root, bio->bi_size), GFP_NOFS);
         if (!sums)
                 return -ENOMEM;
-        *sums_ret = sums;
+
         sector_sum = &sums->sums;
-        sums->file_offset = page_offset(bvec->bv_page);
+        sums->file_offset = page_offset(bvec->bv_page) + bvec->bv_offset;
         sums->len = bio->bi_size;
         INIT_LIST_HEAD(&sums->list);
+        ordered = btrfs_lookup_ordered_extent(inode, sums->file_offset);
+        BUG_ON(!ordered);
 
         while(bio_index < bio->bi_vcnt) {
+                offset = page_offset(bvec->bv_page) + bvec->bv_offset;
+                if (offset >= ordered->file_offset + ordered->len) {
+                        unsigned long bytes_left;
+                        sums->len = this_sum_bytes;
+                        this_sum_bytes = 0;
+                        btrfs_add_ordered_sum(inode, ordered, sums);
+                        btrfs_put_ordered_extent(ordered);
+
+                        bytes_left = bio->bi_size - total_bytes;
+
+                        sums = kzalloc(btrfs_ordered_sum_size(root, bytes_left),
+                                       GFP_NOFS);
+                        BUG_ON(!sums);
+                        sector_sum = &sums->sums;
+                        sums->len = bytes_left;
+                        sums->file_offset = offset;
+                        ordered = btrfs_lookup_ordered_extent(inode,
+                                                      sums->file_offset);
+                        BUG_ON(!ordered);
+                }
+
                 data = kmap_atomic(bvec->bv_page, KM_USER0);
                 sector_sum->sum = ~(u32)0;
                 sector_sum->sum = btrfs_csum_data(root,
@@ -165,10 +192,18 @@ int btrfs_csum_one_bio(struct btrfs_root *root,
                                  (char *)&sector_sum->sum);
                 sector_sum->offset = page_offset(bvec->bv_page) +
                         bvec->bv_offset;
+
                 sector_sum++;
                 bio_index++;
+                total_bytes += bvec->bv_len;
+                this_sum_bytes += bvec->bv_len;
                 bvec++;
         }
+        btrfs_add_ordered_sum(inode, ordered, sums);
+        btrfs_put_ordered_extent(ordered);
+        if (total_bytes != bio->bi_size) {
+printk("warning, total bytes %lu bio size %u\n", total_bytes, bio->bi_size);
+        }
         return 0;
 }