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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: Mikulas Patocka <mpatocka@redhat.com>
Cc: stable@vger.kernel.org
Acked-by: Alasdair G Kergon <agk@redhat.com>
Signed-off-by: Mike Snitzer <snitzer@redhat.com>
This commit is contained in:
Mikulas Patocka 2013-10-31 13:55:45 -04:00 committed by Mike Snitzer
parent 61e6cfa80d
commit f36afb3957
1 changed files with 16 additions and 2 deletions
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18
drivers/md/dm-table.c
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@ -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;