Commit ae643a74 authored by Qu Wenruo's avatar Qu Wenruo Committed by David Sterba
Browse files

btrfs: introduce a data checksum checking helper 



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: default avatarNikolay Borisov <nborisov@suse.com>
Signed-off-by: default avatarQu 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: default avatarChristoph Hellwig <hch@lst.de>
Reviewed-by: default avatarDavid Sterba <dsterba@suse.com>
Signed-off-by: default avatarDavid Sterba <dsterba@suse.com>
parent b036f479

fs/btrfs/compression.c

+4 −9
Original line number Diff line number Diff line
@@ -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)

fs/btrfs/ctree.h

+2 −0
Original line number Diff line number Diff line
@@ -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);

fs/btrfs/inode.c

+28 −10
Original line number Diff line number Diff line
@@ -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);