From 04d4ba4c90759844fb4ffa735214c1c41508d2f7 Mon Sep 17 00:00:00 2001 From: Qu Wenruo Date: Thu, 4 Feb 2021 15:03:24 +0800 Subject: [PATCH] btrfs: make check_compressed_csum() to be subpage compatible Currently check_compressed_csum() completely relies on sectorsize == PAGE_SIZE to do checksum verification for compressed extents. To make it subpage compatible, this patch will: - Do extra calculation for the csum range Since we have multiple sectors inside a page, we need to only hash the range we want, not the full page anymore. - Do sector-by-sector hash inside the page With this patch and previous conversion on btrfs_submit_compressed_read(), now we can read subpage compressed extents properly, and do proper csum verification. Reviewed-by: Anand Jain Signed-off-by: Qu Wenruo Signed-off-by: David Sterba --- fs/btrfs/compression.c | 39 ++++++++++++++++++++++++++------------- 1 file changed, 26 insertions(+), 13 deletions(-) diff --git a/fs/btrfs/compression.c b/fs/btrfs/compression.c index 5bad3a0..375dee6 100644 --- a/fs/btrfs/compression.c +++ b/fs/btrfs/compression.c @@ -141,6 +141,7 @@ static int check_compressed_csum(struct btrfs_inode *inode, struct bio *bio, 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 long i; char *kaddr; @@ -154,22 +155,34 @@ static int check_compressed_csum(struct btrfs_inode *inode, struct bio *bio, shash->tfm = fs_info->csum_shash; for (i = 0; i < cb->nr_pages; i++) { + u32 pg_offset; + u32 bytes_left = PAGE_SIZE; page = cb->compressed_pages[i]; - kaddr = kmap_atomic(page); - crypto_shash_digest(shash, kaddr, PAGE_SIZE, csum); - kunmap_atomic(kaddr); - - if (memcmp(&csum, cb_sum, csum_size)) { - btrfs_print_data_csum_error(inode, disk_start, - csum, cb_sum, cb->mirror_num); - if (btrfs_io_bio(bio)->device) - btrfs_dev_stat_inc_and_print( - btrfs_io_bio(bio)->device, - BTRFS_DEV_STAT_CORRUPTION_ERRS); - return -EIO; + /* Determine the remaining bytes inside the page first */ + if (i == cb->nr_pages - 1) + bytes_left = cb->compressed_len - i * PAGE_SIZE; + + /* 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); + + if (memcmp(&csum, cb_sum, csum_size) != 0) { + btrfs_print_data_csum_error(inode, disk_start, + csum, cb_sum, cb->mirror_num); + if (btrfs_io_bio(bio)->device) + btrfs_dev_stat_inc_and_print( + btrfs_io_bio(bio)->device, + BTRFS_DEV_STAT_CORRUPTION_ERRS); + return -EIO; + } + cb_sum += csum_size; + disk_start += sectorsize; } - cb_sum += csum_size; } return 0; } -- 2.7.4