[patch V3 02/10] dm/verity_fec: Use GFP aware reed solomon init

[Thomas Gleixner]

Allocations from the rs_pool can invoke init_rs() from the mempool
allocation callback. This is problematic in fec_alloc_bufs() which invokes
mempool_alloc() with GFP_NOIO to prevent a swap deadlock because init_rs()
uses GFP_KERNEL allocations.

Switch it to init_rs_gfp() and invoke it with the gfp_t flags which are
handed in from the allocator.

Note: This is not a problem today because the rs control struct is shared
between the instances and its created when the mempool is initialized. But
the upcoming changes which switch to a rs_control struct per instance to
embed decoder buffers will trigger the swap vs. GFP_KERNEL issue.

Signed-off-by: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
Cc: Mike Snitzer <snitzer@xxxxxxxxxx>
Cc: Alasdair Kergon <agk@xxxxxxxxxx>
Cc: Neil Brown <neilb@xxxxxxxx>
---
 drivers/md/dm-verity-fec.c |    2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

--- a/drivers/md/dm-verity-fec.c
+++ b/drivers/md/dm-verity-fec.c
@@ -570,7 +570,7 @@ static void *fec_rs_alloc(gfp_t gfp_mask
 {
 	struct dm_verity *v = (struct dm_verity *)pool_data;
 
-	return init_rs(8, 0x11d, 0, 1, v->fec->roots);
+	return init_rs_gfp(8, 0x11d, 0, 1, v->fec->roots, gfp_mask);
 }
 
 static void fec_rs_free(void *element, void *pool_data)