[dm-devel] [PATCH] dm-zoned: remove test for impossible conditions

[Mikulas Patocka]

Hi

Here I send a patch that removes some impossible code from dm-zoned. The 
target also contains large number of GFP_KERNEL allocations, they should 
be changed to GFP_NOIO, if I/O processing could be delayed because of the 
allocation (i.e. anywhere except initialization you should use GFP_NOIO).

Regarding this "if (!nr_sectors && bio_op(bio) != REQ_OP_WRITE)" - could 
this be removed too? Does it really process some zero-sized requests that 
are not flushes? It doesn't seem so.

Mikulas


From: Mikulas Patocka <mpatocka at redhat.com>

The value REQ_OP_FLUSH is used by the block code in the request structure. 
It is not used in the bio structure.

This patch removes the tests for REQ_OP_FLUSH from dm-zoned-target.

Signed-off-by: Mikulas Patocka <mpatocka at redhat.com>

---
 drivers/md/dm-zoned-target.c |    4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

Index: linux-2.6/drivers/md/dm-zoned-target.c
===================================================================
--- linux-2.6.orig/drivers/md/dm-zoned-target.c
+++ linux-2.6/drivers/md/dm-zoned-target.c
@@ -588,7 +588,7 @@ static int dmz_map(struct dm_target *ti,
 
 	bio->bi_bdev = dev->bdev;
 
-	if (!nr_sectors && (bio_op(bio) != REQ_OP_FLUSH) && (bio_op(bio) != REQ_OP_WRITE))
+	if (!nr_sectors && bio_op(bio) != REQ_OP_WRITE)
 		return DM_MAPIO_REMAPPED;
 
 	/* The BIO should be block aligned */
@@ -603,7 +603,7 @@ static int dmz_map(struct dm_target *ti,
 	bioctx->status = BLK_STS_OK;
 
 	/* Set the BIO pending in the flush list */
-	if (bio_op(bio) == REQ_OP_FLUSH || (!nr_sectors && bio_op(bio) == REQ_OP_WRITE)) {
+	if (!nr_sectors && bio_op(bio) == REQ_OP_WRITE) {
 		spin_lock(&dmz->flush_lock);
 		bio_list_add(&dmz->flush_list, bio);
 		spin_unlock(&dmz->flush_lock);