[PATCH RFC 3/7] fs/btrfs: support `DISABLE_FS_CSUM_VERIFICATION` config option

[Hrutvik Kanabar]

From: Hrutvik Kanabar <hrutvik@xxxxxxxxxx>

When `DISABLE_FS_CSUM_VERIFICATION` is enabled, bypass checksum
verification.

Signed-off-by: Hrutvik Kanabar <hrutvik@xxxxxxxxxx>
---
 fs/btrfs/check-integrity.c  | 3 ++-
 fs/btrfs/disk-io.c          | 6 ++++--
 fs/btrfs/free-space-cache.c | 3 ++-
 fs/btrfs/inode.c            | 3 ++-
 fs/btrfs/scrub.c            | 9 ++++++---
 5 files changed, 16 insertions(+), 8 deletions(-)

diff --git a/fs/btrfs/check-integrity.c b/fs/btrfs/check-integrity.c
index 98c6e5feab19..eab82593a325 100644
--- a/fs/btrfs/check-integrity.c
+++ b/fs/btrfs/check-integrity.c
@@ -1671,7 +1671,8 @@ static noinline_for_stack int btrfsic_test_for_metadata(
 		crypto_shash_update(shash, data, sublen);
 	}
 	crypto_shash_final(shash, csum);
-	if (memcmp(csum, h->csum, fs_info->csum_size))
+	if (!IS_ENABLED(CONFIG_DISABLE_FS_CSUM_VERIFICATION) &&
+	    memcmp(csum, h->csum, fs_info->csum_size))
 		return 1;
 
 	return 0; /* is metadata */
diff --git a/fs/btrfs/disk-io.c b/fs/btrfs/disk-io.c
index a2da9313c694..7cd909d44b24 100644
--- a/fs/btrfs/disk-io.c
+++ b/fs/btrfs/disk-io.c
@@ -184,7 +184,8 @@ static int btrfs_check_super_csum(struct btrfs_fs_info *fs_info,
 	crypto_shash_digest(shash, raw_disk_sb + BTRFS_CSUM_SIZE,
 			    BTRFS_SUPER_INFO_SIZE - BTRFS_CSUM_SIZE, result);
 
-	if (memcmp(disk_sb->csum, result, fs_info->csum_size))
+	if (!IS_ENABLED(CONFIG_DISABLE_FS_CSUM_VERIFICATION) &&
+	    memcmp(disk_sb->csum, result, fs_info->csum_size))
 		return 1;
 
 	return 0;
@@ -494,7 +495,8 @@ static int validate_extent_buffer(struct extent_buffer *eb)
 	header_csum = page_address(eb->pages[0]) +
 		get_eb_offset_in_page(eb, offsetof(struct btrfs_header, csum));
 
-	if (memcmp(result, header_csum, csum_size) != 0) {
+	if (!IS_ENABLED(CONFIG_DISABLE_FS_CSUM_VERIFICATION) &&
+	    memcmp(result, header_csum, csum_size) != 0) {
 		btrfs_warn_rl(fs_info,
 "checksum verify failed on logical %llu mirror %u wanted " CSUM_FMT " found " CSUM_FMT " level %d",
 			      eb->start, eb->read_mirror,
diff --git a/fs/btrfs/free-space-cache.c b/fs/btrfs/free-space-cache.c
index f4023651dd68..203c8a9076a6 100644
--- a/fs/btrfs/free-space-cache.c
+++ b/fs/btrfs/free-space-cache.c
@@ -574,7 +574,8 @@ static int io_ctl_check_crc(struct btrfs_io_ctl *io_ctl, int index)
 	io_ctl_map_page(io_ctl, 0);
 	crc = btrfs_crc32c(crc, io_ctl->orig + offset, PAGE_SIZE - offset);
 	btrfs_crc32c_final(crc, (u8 *)&crc);
-	if (val != crc) {
+	if (!IS_ENABLED(CONFIG_DISABLE_FS_CSUM_VERIFICATION) &&
+	    val != crc) {
 		btrfs_err_rl(io_ctl->fs_info,
 			"csum mismatch on free space cache");
 		io_ctl_unmap_page(io_ctl);
diff --git a/fs/btrfs/inode.c b/fs/btrfs/inode.c
index b0807c59e321..1a49d897b5c1 100644
--- a/fs/btrfs/inode.c
+++ b/fs/btrfs/inode.c
@@ -3434,7 +3434,8 @@ int btrfs_check_sector_csum(struct btrfs_fs_info *fs_info, struct page *page,
 	crypto_shash_digest(shash, kaddr, fs_info->sectorsize, csum);
 	kunmap_local(kaddr);
 
-	if (memcmp(csum, csum_expected, fs_info->csum_size))
+	if (!IS_ENABLED(CONFIG_DISABLE_FS_CSUM_VERIFICATION) &&
+	    memcmp(csum, csum_expected, fs_info->csum_size))
 		return -EIO;
 	return 0;
 }
diff --git a/fs/btrfs/scrub.c b/fs/btrfs/scrub.c
index f260c53829e5..a7607b492f47 100644
--- a/fs/btrfs/scrub.c
+++ b/fs/btrfs/scrub.c
@@ -1997,7 +1997,8 @@ static int scrub_checksum_data(struct scrub_block *sblock)
 
 	crypto_shash_digest(shash, kaddr, fs_info->sectorsize, csum);
 
-	if (memcmp(csum, sector->csum, fs_info->csum_size))
+	if (!IS_ENABLED(CONFIG_DISABLE_FS_CSUM_VERIFICATION) &&
+	    memcmp(csum, sector->csum, fs_info->csum_size))
 		sblock->checksum_error = 1;
 	return sblock->checksum_error;
 }
@@ -2062,7 +2063,8 @@ static int scrub_checksum_tree_block(struct scrub_block *sblock)
 	}
 
 	crypto_shash_final(shash, calculated_csum);
-	if (memcmp(calculated_csum, on_disk_csum, sctx->fs_info->csum_size))
+	if (!IS_ENABLED(CONFIG_DISABLE_FS_CSUM_VERIFICATION) &&
+	    memcmp(calculated_csum, on_disk_csum, sctx->fs_info->csum_size))
 		sblock->checksum_error = 1;
 
 	return sblock->header_error || sblock->checksum_error;
@@ -2099,7 +2101,8 @@ static int scrub_checksum_super(struct scrub_block *sblock)
 	crypto_shash_digest(shash, kaddr + BTRFS_CSUM_SIZE,
 			BTRFS_SUPER_INFO_SIZE - BTRFS_CSUM_SIZE, calculated_csum);
 
-	if (memcmp(calculated_csum, s->csum, sctx->fs_info->csum_size))
+	if (!IS_ENABLED(CONFIG_DISABLE_FS_CSUM_VERIFICATION) &&
+	    memcmp(calculated_csum, s->csum, sctx->fs_info->csum_size))
 		++fail_cor;
 
 	return fail_cor + fail_gen;
-- 
2.38.0.413.g74048e4d9e-goog