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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>
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1 changed files with 16 additions and 2 deletions
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@ -545,14 +545,28 @@ static int adjoin(struct dm_table *table, struct dm_target *ti)
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/*
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* Used to dynamically allocate the arg array.
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*
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* We do first allocation with GFP_NOIO because dm-mpath and dm-thin must
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* process messages even if some device is suspended. These messages have a
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* small fixed number of arguments.
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*
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* On the other hand, dm-switch needs to process bulk data using messages and
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* excessive use of GFP_NOIO could cause trouble.
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*/
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static char **realloc_argv(unsigned *array_size, char **old_argv)
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{
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char **argv;
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unsigned new_size;
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gfp_t gfp;
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new_size = *array_size ? *array_size * 2 : 64;
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argv = kmalloc(new_size * sizeof(*argv), GFP_KERNEL);
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if (*array_size) {
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new_size = *array_size * 2;
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gfp = GFP_KERNEL;
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} else {
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new_size = 8;
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gfp = GFP_NOIO;
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}
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argv = kmalloc(new_size * sizeof(*argv), gfp);
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if (argv) {
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memcpy(argv, old_argv, *array_size * sizeof(*argv));
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*array_size = new_size;
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