On 08/07/2015 03:05 AM, Chandan Rajendra wrote:
Checksums are applicable to sectorsize units. The current code uses
bio->bv_len units to compute and look up checksums. This works on machines
where sectorsize == PAGE_SIZE. This patch makes the checksum computation and
look up code to work with sectorsize units.

Reviewed-by: Liu Bo <[email protected]>
Signed-off-by: Chandan Rajendra <[email protected]>
---
  fs/btrfs/file-item.c | 90 +++++++++++++++++++++++++++++++++-------------------
  1 file changed, 57 insertions(+), 33 deletions(-)

diff --git a/fs/btrfs/file-item.c b/fs/btrfs/file-item.c
index 58ece65..d752051 100644
--- a/fs/btrfs/file-item.c
+++ b/fs/btrfs/file-item.c
@@ -172,6 +172,7 @@ static int __btrfs_lookup_bio_sums(struct btrfs_root *root,
        u64 item_start_offset = 0;
        u64 item_last_offset = 0;
        u64 disk_bytenr;
+       u64 page_bytes_left;
        u32 diff;
        int nblocks;
        int bio_index = 0;
@@ -220,6 +221,8 @@ static int __btrfs_lookup_bio_sums(struct btrfs_root *root,
        disk_bytenr = (u64)bio->bi_iter.bi_sector << 9;
        if (dio)
                offset = logical_offset;
+
+       page_bytes_left = bvec->bv_len;
        while (bio_index < bio->bi_vcnt) {
                if (!dio)
                        offset = page_offset(bvec->bv_page) + bvec->bv_offset;
@@ -243,7 +246,7 @@ static int __btrfs_lookup_bio_sums(struct btrfs_root *root,
                                if (BTRFS_I(inode)->root->root_key.objectid ==
                                    BTRFS_DATA_RELOC_TREE_OBJECTID) {
                                        set_extent_bits(io_tree, offset,
-                                               offset + bvec->bv_len - 1,
+                                               offset + root->sectorsize - 1,
                                                EXTENT_NODATASUM, GFP_NOFS);
                                } else {
                                        
btrfs_info(BTRFS_I(inode)->root->fs_info,
@@ -281,11 +284,17 @@ static int __btrfs_lookup_bio_sums(struct btrfs_root 
*root,
  found:
                csum += count * csum_size;
                nblocks -= count;
-               bio_index += count;
+
                while (count--) {
-                       disk_bytenr += bvec->bv_len;
-                       offset += bvec->bv_len;
-                       bvec++;
+                       disk_bytenr += root->sectorsize;
+                       offset += root->sectorsize;
+                       page_bytes_left -= root->sectorsize;
+                       if (!page_bytes_left) {
+                               bio_index++;
+                               bvec++;
+                               page_bytes_left = bvec->bv_len;
+                       }
+
                }
        }
        btrfs_free_path(path);
@@ -432,6 +441,8 @@ int btrfs_csum_one_bio(struct btrfs_root *root, struct 
inode *inode,
        struct bio_vec *bvec = bio->bi_io_vec;
        int bio_index = 0;
        int index;
+       int nr_sectors;
+       int i;
        unsigned long total_bytes = 0;
        unsigned long this_sum_bytes = 0;
        u64 offset;
@@ -459,41 +470,54 @@ int btrfs_csum_one_bio(struct btrfs_root *root, struct 
inode *inode,
                if (!contig)
                        offset = page_offset(bvec->bv_page) + bvec->bv_offset;

-               if (offset >= ordered->file_offset + ordered->len ||
-                   offset < ordered->file_offset) {
-                       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);
+               data = kmap_atomic(bvec->bv_page);


I don't think we can have something kmap_atomic()'ed and then do allocations under it right? That's why we only kmap_atomic(), do the copy, and then unmap, unless I'm forgetting something? Thanks,

Josef
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