From patchwork Wed Dec 19 21:07:11 2012
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Subject: dm-crypt: never use write same (was Re: [v3.7 Regression] [SCSI] sd:
 Implement support for WRITE SAME)
Date: Wed, 19 Dec 2012 11:07:11 -0000
From: Milan Broz <mbroz@redhat.com>
X-Patchwork-Id: 207803
Message-Id: <50D22C7F.2020201@redhat.com>
To: Mike Snitzer <snitzer@redhat.com>
Cc: "Martin K. Petersen" <martin.petersen@oracle.com>,
 linux-kernel@vger.kernel.org, JBottomley@Parallels.com,
 Kernel Team <kernel-team@lists.ubuntu.com>, jgarzik@redhat.com

Does this help?

dm-crypt: never use write same

Ciphertext device is not compatible with WRITE SAME,
disable it for all dmcrypt devices.

Signed-off-by: Milan Broz <mbroz@redhat.com>
Acked-by: Martin K. Petersen <martin.petersen@oracle.com>


--- a/drivers/md/dm-crypt.c
+++ b/drivers/md/dm-crypt.c
@@ -1844,6 +1844,12 @@ static int crypt_iterate_devices(struct dm_target *ti,
 	return fn(ti, cc->dev, cc->start, ti->len, data);
 }
 
+static void crypt_io_hints(struct dm_target *ti,
+			    struct queue_limits *limits)
+{
+	limits->max_write_same_sectors = 0;
+}
+
 static struct target_type crypt_target = {
 	.name   = "crypt",
 	.version = {1, 11, 0},
@@ -1858,6 +1864,7 @@ static struct target_type crypt_target = {
 	.message = crypt_message,
 	.merge  = crypt_merge,
 	.iterate_devices = crypt_iterate_devices,
+	.io_hints = crypt_io_hints,
 };
 
 static int __init dm_crypt_init(void)