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Commit 833ff408 authored by Jaegeuk Kim's avatar Jaegeuk Kim Committed by Greg Kroah-Hartman
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dm verity fec: fix misaligned RS roots IO 



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: default avatarJaegeuk Kim <jaegeuk@google.com>
Signed-off-by: default avatarMike Snitzer <snitzer@redhat.com>
Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
parent 38ece8ce

drivers/md/dm-verity-fec.c

+8 −3
Original line number Diff line number Diff line
@@ -69,7 +69,7 @@ static u8 *fec_read_parity(struct dm_verity *v, u64 rsb, int index, 
	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);
@@ -158,7 +158,7 @@ static int fec_decode_bufs(struct dm_verity *v, struct dm_verity_fec_io *fio, 


		/* 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);
@@ -743,8 +743,13 @@ 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";

drivers/md/dm-verity-fec.h

+1 −0
Original line number Diff line number Diff line
@@ -40,6 +40,7 @@ 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 */