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btrfs: introduce a data checksum checking helper

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Although we have several data csum verification code, we never have a
function really just to verify checksum for one sector.

Function check_data_csum() do extra work for error reporting, thus it
requires a lot of extra things like file offset, bio_offset etc.

Function btrfs_verify_data_csum() is even worse, it will utilize page
checked flag, which means it can not be utilized for direct IO pages.

Here we introduce a new helper, btrfs_check_sector_csum(), which really
only accept a sector in page, and expected checksum pointer.

We use this function to implement check_data_csum(), and export it for
incoming patch.

Reviewed-by: Nikolay Borisov <nborisov@suse.com>
Signed-off-by: Qu Wenruo <wqu@suse.com>
[hch: keep passing the csum array as an arguments, as the callers want
      to print it, rename per request]
Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
This commit is contained in:
Qu Wenruo 2022-05-22 13:47:48 +02:00 committed by David Sterba
parent b036f47996
commit ae643a74eb
3 changed files with 34 additions and 19 deletions
repo.diff.show_diff_stats Download patch file Download diff file Expand all files Collapse all files

13
fs/btrfs/compression.c
View file

@ -147,12 +147,10 @@ static int check_compressed_csum(struct btrfs_inode *inode, struct bio *bio,
u64 disk_start)
{
struct btrfs_fs_info *fs_info = inode->root->fs_info;
SHASH_DESC_ON_STACK(shash, fs_info->csum_shash);
const u32 csum_size = fs_info->csum_size;
const u32 sectorsize = fs_info->sectorsize;
struct page *page;
unsigned int i;
char *kaddr;
u8 csum[BTRFS_CSUM_SIZE];
struct compressed_bio *cb = bio->bi_private;
u8 *cb_sum = cb->sums;
@ -161,8 +159,6 @@ static int check_compressed_csum(struct btrfs_inode *inode, struct bio *bio,
test_bit(BTRFS_FS_STATE_NO_CSUMS, &fs_info->fs_state))
return 0;
shash->tfm = fs_info->csum_shash;
for (i = 0; i < cb->nr_pages; i++) {
u32 pg_offset;
u32 bytes_left = PAGE_SIZE;
@ -175,12 +171,11 @@ static int check_compressed_csum(struct btrfs_inode *inode, struct bio *bio,
/* Hash through the page sector by sector */
for (pg_offset = 0; pg_offset < bytes_left;
pg_offset += sectorsize) {
kaddr = kmap_atomic(page);
crypto_shash_digest(shash, kaddr + pg_offset,
sectorsize, csum);
kunmap_atomic(kaddr);
int ret;
if (memcmp(&csum, cb_sum, csum_size) != 0) {
ret = btrfs_check_sector_csum(fs_info, page, pg_offset,
csum, cb_sum);
if (ret) {
btrfs_print_data_csum_error(inode, disk_start,
csum, cb_sum, cb->mirror_num);
if (btrfs_bio(bio)->device)

2
fs/btrfs/ctree.h
View file

@ -3253,6 +3253,8 @@ u64 btrfs_file_extent_end(const struct btrfs_path *path);
/* inode.c */
void btrfs_submit_data_bio(struct inode *inode, struct bio *bio,
int mirror_num, enum btrfs_compression_type compress_type);
int btrfs_check_sector_csum(struct btrfs_fs_info *fs_info, struct page *page,
u32 pgoff, u8 *csum, const u8 * const csum_expected);
unsigned int btrfs_verify_data_csum(struct btrfs_bio *bbio,
u32 bio_offset, struct page *page,
u64 start, u64 end);

38
fs/btrfs/inode.c
View file

@ -3328,6 +3328,29 @@ void btrfs_writepage_endio_finish_ordered(struct btrfs_inode *inode,
finish_ordered_fn, uptodate);
}
/*
* Verify the checksum for a single sector without any extra action that depend
* on the type of I/O.
*/
int btrfs_check_sector_csum(struct btrfs_fs_info *fs_info, struct page *page,
u32 pgoff, u8 *csum, const u8 * const csum_expected)
{
SHASH_DESC_ON_STACK(shash, fs_info->csum_shash);
char *kaddr;
ASSERT(pgoff + fs_info->sectorsize <= PAGE_SIZE);
shash->tfm = fs_info->csum_shash;
kaddr = kmap_local_page(page) + pgoff;
crypto_shash_digest(shash, kaddr, fs_info->sectorsize, csum);
kunmap_local(kaddr);
if (memcmp(csum, csum_expected, fs_info->csum_size))
return -EIO;
return 0;
}
/*
* check_data_csum - verify checksum of one sector of uncompressed data
* @inode: inode
@ -3338,14 +3361,15 @@ void btrfs_writepage_endio_finish_ordered(struct btrfs_inode *inode,
* @start: logical offset in the file
*
* The length of such check is always one sector size.
*
* When csum mismatch is detected, we will also report the error and fill the
* corrupted range with zero. (Thus it needs the extra parameters)
*/
static int check_data_csum(struct inode *inode, struct btrfs_bio *bbio,
u32 bio_offset, struct page *page, u32 pgoff,
u64 start)
{
struct btrfs_fs_info *fs_info = btrfs_sb(inode->i_sb);
SHASH_DESC_ON_STACK(shash, fs_info->csum_shash);
char *kaddr;
u32 len = fs_info->sectorsize;
const u32 csum_size = fs_info->csum_size;
unsigned int offset_sectors;
@ -3357,16 +3381,10 @@ static int check_data_csum(struct inode *inode, struct btrfs_bio *bbio,
offset_sectors = bio_offset >> fs_info->sectorsize_bits;
csum_expected = ((u8 *)bbio->csum) + offset_sectors * csum_size;
kaddr = kmap_atomic(page);
shash->tfm = fs_info->csum_shash;
crypto_shash_digest(shash, kaddr + pgoff, len, csum);
kunmap_atomic(kaddr);
if (memcmp(csum, csum_expected, csum_size))
if (btrfs_check_sector_csum(fs_info, page, pgoff, csum, csum_expected))
goto zeroit;
return 0;
zeroit:
btrfs_print_data_csum_error(BTRFS_I(inode), start, csum, csum_expected,
bbio->mirror_num);