Re: [PATCH 1/3] libata: Whitelist SSDs that are known to properly return zeroes after TRIM

The whitelist is only meant as a starting point and is by no means
comprehensive:

   - All intel SSD models except for 510
   - Micron M5*
   - Samsung SSDs
   - Seagate SSDs

Signed-off-by: Martin K. Petersen <redacted>
---
 drivers/ata/libata-core.c | 18 ++++++++++++++----
 drivers/ata/libata-scsi.c | 10 ++++++----
 include/linux/libata.h    |  1 +
 3 files changed, 21 insertions(+), 8 deletions(-)

diff --git a/drivers/ata/libata-core.c b/drivers/ata/libata-core.c
index c5ba15af87d3..f41f24a8bc21 100644
--- a/drivers/ata/libata-core.c
+++ b/drivers/ata/libata-core.c

@@ -4225,10 +4225,20 @@ static const struct ata_blacklist_entry ata_device_blacklist [] = {
 	{ "PIONEER DVD-RW  DVR-216D",	NULL,	ATA_HORKAGE_NOSETXFER },
 
 	/* devices that don't properly handle queued TRIM commands */
-	{ "Micron_M500*",		NULL,	ATA_HORKAGE_NO_NCQ_TRIM, },
-	{ "Crucial_CT???M500SSD*",	NULL,	ATA_HORKAGE_NO_NCQ_TRIM, },
-	{ "Micron_M550*",		NULL,	ATA_HORKAGE_NO_NCQ_TRIM, },
-	{ "Crucial_CT*M550SSD*",	NULL,	ATA_HORKAGE_NO_NCQ_TRIM, },
+	{ "Micron_M5?0*",		NULL,	ATA_HORKAGE_NO_NCQ_TRIM |
+						ATA_HORKAGE_ZERO_AFTER_TRIM, },
+	{ "Crucial_CT???M5?0SSD*",	NULL,	ATA_HORKAGE_NO_NCQ_TRIM, },

+
+	/*
+	 * DRAT/RZAT are weak guarantees. Explicitly black/whitelist
+	 * SSDs that provide reliable zero after TRIM.
+	 */
+	{ "INTEL*SSDSC2MH*",		NULL,	0, }, /* Blacklist intel 510 */
+	{ "INTEL*SSD*", 		NULL,	ATA_HORKAGE_ZERO_AFTER_TRIM, },
+	{ "SSD*INTEL*",			NULL,	ATA_HORKAGE_ZERO_AFTER_TRIM, },
+	{ "Samsung*SSD*",		NULL,	ATA_HORKAGE_ZERO_AFTER_TRIM, },
+	{ "SAMSUNG*SSD*",		NULL,	ATA_HORKAGE_ZERO_AFTER_TRIM, },
+	{ "ST[1248][0248]0[FH]*",	NULL,	ATA_HORKAGE_ZERO_AFTER_TRIM, },
 
 	/*
 	 * Some WD SATA-I drives spin up and down erratically when the link

diff --git a/drivers/ata/libata-scsi.c b/drivers/ata/libata-scsi.c
index 0586f66d70fa..deaa6e34ed4d 100644
--- a/drivers/ata/libata-scsi.c
+++ b/drivers/ata/libata-scsi.c

@@ -2515,13 +2515,15 @@ static unsigned int ata_scsiop_read_cap(struct ata_scsi_args *args, u8 *rbuf)
 		rbuf[15] = lowest_aligned;
 
 		if (ata_id_has_trim(args->id)) {
-			rbuf[14] |= 0x80; /* TPE */
+			rbuf[14] |= 0x80; /* LBPME */
 
-			if (ata_id_has_zero_after_trim(args->id))
-				rbuf[14] |= 0x40; /* TPRZ */
+			if (ata_id_has_zero_after_trim(args->id) &&
+			    dev->horkage & ATA_HORKAGE_ZERO_AFTER_TRIM) {
+				ata_dev_warn(dev, "Enabling discard_zeroes_data\n");
+				rbuf[14] |= 0x40; /* LBPRZ */
+			}
 		}
 	}
-
 	return 0;
 }
 

diff --git a/include/linux/libata.h b/include/linux/libata.h
index bd5fefeaf548..45ac825b8366 100644
--- a/include/linux/libata.h
+++ b/include/linux/libata.h

@@ -421,6 +421,7 @@ enum {
 	ATA_HORKAGE_NO_NCQ_TRIM	= (1 << 19),	/* don't use queued TRIM */
 	ATA_HORKAGE_NOLPM	= (1 << 20),	/* don't use LPM */
 	ATA_HORKAGE_WD_BROKEN_LPM = (1 << 21),	/* some WDs have broken LPM */
+	ATA_HORKAGE_ZERO_AFTER_TRIM = (1 << 22),/* guarantees zero after trim */
 
 	 /* DMA mask for user DMA control: User visible values; DO NOT
 	    renumber */