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Commit f36afb39 authored by Mikulas Patocka's avatar Mikulas Patocka Committed by Mike Snitzer
Browse files

dm: allocate buffer for messages with small number of arguments using GFP_NOIO 



dm-mpath and dm-thin must process messages even if some device is
suspended, so we allocate argv buffer with GFP_NOIO. These messages have
a small fixed number of arguments.

On the other hand, dm-switch needs to process bulk data using messages
so excessive use of GFP_NOIO could cause trouble.

The patch also lowers the default number of arguments from 64 to 8, so
that there is smaller load on GFP_NOIO allocations.

Signed-off-by: default avatarMikulas Patocka <mpatocka@redhat.com>
Cc: stable@vger.kernel.org
Acked-by: default avatarAlasdair G Kergon <agk@redhat.com>
Signed-off-by: default avatarMike Snitzer <snitzer@redhat.com>
parent 61e6cfa8

drivers/md/dm-table.c

+16 −2
Original line number Diff line number Diff line
@@ -545,14 +545,28 @@ static int adjoin(struct dm_table *table, struct dm_target *ti) 


/*

 * Used to dynamically allocate the arg array.

 *

 * We do first allocation with GFP_NOIO because dm-mpath and dm-thin must

 * process messages even if some device is suspended. These messages have a

 * small fixed number of arguments.

 *

 * On the other hand, dm-switch needs to process bulk data using messages and

 * excessive use of GFP_NOIO could cause trouble.

 */

static char **realloc_argv(unsigned *array_size, char **old_argv)

{

	char **argv;

	unsigned new_size;

	gfp_t gfp;



	new_size = *array_size ? *array_size * 2 : 64;

	argv = kmalloc(new_size * sizeof(*argv), GFP_KERNEL);

	if (*array_size) {

		new_size = *array_size * 2;

		gfp = GFP_KERNEL;

	} else {

		new_size = 8;

		gfp = GFP_NOIO;

	}

	argv = kmalloc(new_size * sizeof(*argv), gfp);

	if (argv) {

		memcpy(argv, old_argv, *array_size * sizeof(*argv));

		*array_size = new_size;