[PATCH 5.11 059/122] dm verity fec: fix misaligned RS roots IO

Greg Kroah-Hartman
2021-04-19T13:11:45Z

From: Jaegeuk Kim <jaegeuk@google.com>

commit 8ca7cab82bda4eb0b8064befeeeaa38106cac637 upstream.

commit df7b59ba9245 ("dm verity: fix FEC for RS roots unaligned to
block size") introduced the possibility for misaligned roots IO
relative to the underlying device's logical block size. E.g. Android's
default RS roots=2 results in dm_bufio->block_size=1024, which causes
the following EIO if the logical block size of the device is 4096,
given v->data_dev_block_bits=12:

E sd 0 : 0:0:0: [sda] tag#30 request not aligned to the logical block size
E blk_update_request: I/O error, dev sda, sector 10368424 op 0x0:(READ) flags 0x0 phys_seg 1 prio class 0
E device-mapper: verity-fec: 254:8: FEC 9244672: parity read failed (block 18056): -5

Fix this by onlu using f->roots for dm_bufio blocksize IFF it is
aligned to v->data_dev_block_bits.

Fixes: df7b59ba9245 ("dm verity: fix FEC for RS roots unaligned to block size")
Cc: stable@vger.kernel.org
Signed-off-by: Jaegeuk Kim <jaegeuk@google.com>
Signed-off-by: Mike Snitzer <snitzer@redhat.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
drivers/md/dm-verity-fec.c | 11 ++++++++---
drivers/md/dm-verity-fec.h | 1 +
2 files changed, 9 insertions(+), 3 deletions(-)

--- a/drivers/md/dm-verity-fec.c
+++ b/drivers/md/dm-verity-fec.c
@@ -65,7 +65,7 @@ static u8 *fec_read_parity(struct dm_ver
u8 *res;

position = (index + rsb) * v->fec->roots;
- block = div64_u64_rem(position, v->fec->roots << SECTOR_SHIFT, &rem);
+ block = div64_u64_rem(position, v->fec->io_size, &rem);
*offset = (unsigned)rem;

res = dm_bufio_read(v->fec->bufio, block, buf);
@@ -154,7 +154,7 @@ static int fec_decode_bufs(struct dm_ver

/* read the next block when we run out of parity bytes */
offset += v->fec->roots;
- if (offset >= v->fec->roots << SECTOR_SHIFT) {
+ if (offset >= v->fec->io_size) {
dm_bufio_release(buf);

par = fec_read_parity(v, rsb, block_offset, &offset, &buf);
@@ -742,8 +742,13 @@ int verity_fec_ctr(struct dm_verity *v)
return -E2BIG;
}

+ if ((f->roots << SECTOR_SHIFT) & ((1 << v->data_dev_block_bits) - 1))
+ f->io_size = 1 << v->data_dev_block_bits;
+ else
+ f->io_size = v->fec->roots << SECTOR_SHIFT;
+
f->bufio = dm_bufio_client_create(f->dev->bdev,
- f->roots << SECTOR_SHIFT,
+ f->io_size,
1, 0, NULL, NULL);
if (IS_ERR(f->bufio)) {
ti->error = "Cannot initialize FEC bufio client";
--- a/drivers/md/dm-verity-fec.h
+++ b/drivers/md/dm-verity-fec.h
@@ -36,6 +36,7 @@ struct dm_verity_fec {
struct dm_dev *dev; /* parity data device */
struct dm_bufio_client *data_bufio; /* for data dev access */
struct dm_bufio_client *bufio; /* for parity data access */
+ size_t io_size; /* IO size for roots */
sector_t start; /* parity data start in blocks */
sector_t blocks; /* number of blocks covered */
sector_t rounds; /* number of interleaving rounds */