Commit e75d5546 authored by Eric Biggers's avatar Eric Biggers Committed by Mikulas Patocka
Browse files

dm-verity-fec: replace io_size with block_size 



dm-verity's FEC implementation assumes that data_block_size ==
hash_block_size, and it accesses the FEC device in units of the same
size.  Many places in the code want that size and compute it on-demand
as '1 << v->data_dev_block_bits'.  However, it's actually already
available in v->fec->io_size.  Rename that field to block_size,
initialize it a bit earlier, and use it in the appropriate places.

Note that while these sizes could in principle be different, that case
is not supported.  So there's no need to complicate the code for it.

Signed-off-by: default avatarEric Biggers <ebiggers@kernel.org>
Signed-off-by: default avatarMikulas Patocka <mpatocka@redhat.com>
parent 9b6098ad

drivers/md/dm-verity-fec.c

+13 −17
Original line number Diff line number Diff line
@@ -84,11 +84,11 @@ static int fec_decode_bufs(struct dm_verity *v, struct dm_verity_io *io, 
	 * Compute the index of the first parity block that will be needed and

	 * the starting position in that block.  Then read that block.

	 *

	 * io_size is always a power of 2, but roots might not be.  Note that

	 * block_size is always a power of 2, but roots might not be.  Note that

	 * when it's not, a codeword's parity bytes can span a block boundary.

	 */

	parity_block = (rsb + block_offset) * v->fec->roots;

	parity_pos = parity_block & (v->fec->io_size - 1);

	parity_pos = parity_block & (v->fec->block_size - 1);

	parity_block >>= v->data_dev_block_bits;

	par = dm_bufio_read_with_ioprio(v->fec->bufio, parity_block, &buf,

					bio->bi_ioprio);
@@ -110,7 +110,7 @@ static int fec_decode_bufs(struct dm_verity *v, struct dm_verity_io *io, 
		 * Copy the next 'roots' parity bytes to 'par_buf', reading

		 * another parity block if needed.

		 */

		to_copy = min(v->fec->io_size - parity_pos, v->fec->roots);

		to_copy = min(v->fec->block_size - parity_pos, v->fec->roots);

		for (j = 0; j < to_copy; j++)

			par_buf[j] = par[parity_pos++];

		if (to_copy < v->fec->roots) {
@@ -143,7 +143,7 @@ static int fec_decode_bufs(struct dm_verity *v, struct dm_verity_io *io, 
		fio->output[block_offset] = msg_buf[byte_index];



		block_offset++;

		if (block_offset >= 1 << v->data_dev_block_bits)

		if (block_offset >= v->fec->block_size)

			goto done;

	}

done:
@@ -167,7 +167,7 @@ static int fec_decode_bufs(struct dm_verity *v, struct dm_verity_io *io, 
static int fec_is_erasure(struct dm_verity *v, struct dm_verity_io *io,

			  const u8 *want_digest, const u8 *data)

{

	if (unlikely(verity_hash(v, io, data, 1 << v->data_dev_block_bits,

	if (unlikely(verity_hash(v, io, data, v->fec->block_size,

				 io->tmp_digest)))

		return 0;
@@ -268,7 +268,7 @@ static int fec_read_bufs(struct dm_verity *v, struct dm_verity_io *io, 
		fec_for_each_buffer_rs_message(fio, n, j) {

			k = fec_buffer_rs_index(n, j) + block_offset;



			if (k >= 1 << v->data_dev_block_bits)

			if (k >= v->fec->block_size)

				goto done;



			fec_buffer_rs_message(v, fio, n, j)[i] = bbuf[k];
@@ -341,7 +341,7 @@ static int fec_decode_rsb(struct dm_verity *v, struct dm_verity_io *io, 
	int r, neras = 0;

	unsigned int pos;



	for (pos = 0; pos < 1 << v->data_dev_block_bits; ) {

	for (pos = 0; pos < v->fec->block_size;) {

		fec_init_bufs(v, fio);



		r = fec_read_bufs(v, io, rsb, offset, pos,
@@ -357,8 +357,7 @@ static int fec_decode_rsb(struct dm_verity *v, struct dm_verity_io *io, 
	}



	/* Always re-validate the corrected block against the expected hash */

	r = verity_hash(v, io, fio->output, 1 << v->data_dev_block_bits,

			io->tmp_digest);

	r = verity_hash(v, io, fio->output, v->fec->block_size, io->tmp_digest);

	if (unlikely(r < 0))

		return r;
@@ -426,7 +425,7 @@ int verity_fec_decode(struct dm_verity *v, struct dm_verity_io *io, 
			goto done;

	}



	memcpy(dest, fio->output, 1 << v->data_dev_block_bits);

	memcpy(dest, fio->output, v->fec->block_size);

	atomic64_inc(&v->fec->corrected);



done:
@@ -647,6 +646,7 @@ int verity_fec_ctr(struct dm_verity *v) 
		ti->error = "Block sizes must match to use FEC";

		return -EINVAL;

	}

	f->block_size = 1 << v->data_dev_block_bits;



	if (!f->roots) {

		ti->error = "Missing " DM_VERITY_OPT_FEC_ROOTS;
@@ -684,10 +684,7 @@ int verity_fec_ctr(struct dm_verity *v) 
		return -E2BIG;

	}



	f->io_size = 1 << v->data_dev_block_bits;



	f->bufio = dm_bufio_client_create(f->dev->bdev,

					  f->io_size,

	f->bufio = dm_bufio_client_create(f->dev->bdev, f->block_size,

					  1, 0, NULL, NULL, 0);

	if (IS_ERR(f->bufio)) {

		ti->error = "Cannot initialize FEC bufio client";
@@ -701,8 +698,7 @@ int verity_fec_ctr(struct dm_verity *v) 
		return -E2BIG;

	}



	f->data_bufio = dm_bufio_client_create(v->data_dev->bdev,

					       1 << v->data_dev_block_bits,

	f->data_bufio = dm_bufio_client_create(v->data_dev->bdev, f->block_size,

					       1, 0, NULL, NULL, 0);

	if (IS_ERR(f->data_bufio)) {

		ti->error = "Cannot initialize FEC data bufio client";
@@ -749,7 +745,7 @@ int verity_fec_ctr(struct dm_verity *v) 


	/* Preallocate an output buffer for each thread */

	ret = mempool_init_kmalloc_pool(&f->output_pool, num_online_cpus(),

					1 << v->data_dev_block_bits);

					f->block_size);

	if (ret) {

		ti->error = "Cannot allocate FEC output pool";

		return ret;

drivers/md/dm-verity-fec.h

+1 −1
Original line number Diff line number Diff line
@@ -29,7 +29,7 @@ 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 */

	size_t block_size;	/* size of data, hash, and parity blocks in bytes */

	sector_t start;		/* parity data start in blocks */

	sector_t blocks;	/* number of blocks covered */

	sector_t rounds;	/* number of interleaving rounds */