[PATCH v6 3/4 RESEND] SCT Write Same / DSM Trim

Shaun Tancheff
2016-08-24T19:00:13Z

Correct handling of devices with sector_size other that 512 bytes.

In the case of a 4Kn device sector_size it is possible to describe a much
larger DSM Trim than the current fixed default of 512 bytes.

This patch assumes the minimum descriptor is sector_size and fills out
the descriptor accordingly.

The ACS-2 specification is quite clear that the DSM command payload is
sized as number of 512 byte transfers so a 4Kn device will operate
correctly without this patch.

Signed-off-by: Shaun Tancheff <shaun.tancheff@seagate.com>
---
v5:
- Reshuffled descripton.
- Added support for a sector_size descriptor other than 512 bytes.

drivers/ata/libata-scsi.c | 85 +++++++++++++++++++++++++++++++----------------
1 file changed, 57 insertions(+), 28 deletions(-)

diff --git a/drivers/ata/libata-scsi.c b/drivers/ata/libata-scsi.c
index ebf1a04..37f456e 100644
--- a/drivers/ata/libata-scsi.c
+++ b/drivers/ata/libata-scsi.c
@@ -3283,7 +3283,7 @@ static unsigned int ata_scsi_pass_thru(struct ata_queued_cmd *qc)
/**
* ata_format_dsm_trim_descr() - SATL Write Same to DSM Trim
* @cmd: SCSI command being translated
- * @num: Maximum number of entries (nominally 64).
+ * @trmax: Maximum number of entries that will fit in sector_size bytes.
* @sector: Starting sector
* @count: Total Range of request in logical sectors
*
@@ -3298,63 +3298,80 @@ static unsigned int ata_scsi_pass_thru(struct ata_queued_cmd *qc)
* LBA's should be sorted order and not overlap.
*
* NOTE: this is the same format as ADD LBA(S) TO NV CACHE PINNED SET
+ *
+ * Return: Number of bytes copied into sglist.
*/
-static unsigned int ata_format_dsm_trim_descr(struct scsi_cmnd *cmd, u32 num,
- u64 sector, u32 count)
+static size_t ata_format_dsm_trim_descr(struct scsi_cmnd *cmd, u32 trmax,
+ u64 sector, u32 count)
{
- __le64 *buffer;
- u32 i = 0, used_bytes;
+ struct scsi_device *sdp = cmd->device;
+ size_t len = sdp->sector_size;
+ size_t r;
+ __le64 *buf;
+ u32 i = 0;
unsigned long flags;

- BUILD_BUG_ON(512 > ATA_SCSI_RBUF_SIZE);
+ WARN_ON(len > ATA_SCSI_RBUF_SIZE);
+
+ if (len > ATA_SCSI_RBUF_SIZE)
+ len = ATA_SCSI_RBUF_SIZE;

spin_lock_irqsave(&ata_scsi_rbuf_lock, flags);
- buffer = ((void *)ata_scsi_rbuf);
- while (i < num) {
+ buf = ((void *)ata_scsi_rbuf);
+ memset(buf, 0, len);
+ while (i < trmax) {
u64 entry = sector |
((u64)(count > 0xffff ? 0xffff : count) << 48);
- buffer[i++] = __cpu_to_le64(entry);
+ buf[i++] = __cpu_to_le64(entry);
if (count <= 0xffff)
break;
count -= 0xffff;
sector += 0xffff;
}
-
- used_bytes = ALIGN(i * 8, 512);
- memset(buffer + i, 0, used_bytes - i * 8);
- sg_copy_from_buffer(scsi_sglist(cmd), scsi_sg_count(cmd), buffer, 512);
+ r = sg_copy_from_buffer(scsi_sglist(cmd), scsi_sg_count(cmd), buf, len);
spin_unlock_irqrestore(&ata_scsi_rbuf_lock, flags);

- return used_bytes;
+ return r;
}

/**
* ata_format_dsm_trim_descr() - SATL Write Same to ATA SCT Write Same
* @cmd: SCSI command being translated
* @lba: Starting sector
- * @num: Number of logical sectors to be zero'd.
+ * @num: Number of sectors to be zero'd.
*
- * Rewrite the WRITE SAME descriptor to be an SCT Write Same formatted
+ * Rewrite the WRITE SAME payload to be an SCT Write Same formatted
* descriptor.
* NOTE: Writes a pattern (0's) in the foreground.
- * Large write-same requents can timeout.
+ *
+ * Return: Number of bytes copied into sglist.
*/
-static void ata_format_sct_write_same(struct scsi_cmnd *cmd, u64 lba, u64 num)
+static size_t ata_format_sct_write_same(struct scsi_cmnd *cmd, u64 lba, u64 num)
{
- u16 *sctpg;
+ struct scsi_device *sdp = cmd->device;
+ size_t len = sdp->sector_size;
+ size_t r;
+ u16 *buf;
unsigned long flags;

spin_lock_irqsave(&ata_scsi_rbuf_lock, flags);
- sctpg = ((void *)ata_scsi_rbuf);
+ buf = ((void *)ata_scsi_rbuf);
+
+ put_unaligned_le16(0x0002, &buf[0]); /* SCT_ACT_WRITE_SAME */
+ put_unaligned_le16(0x0101, &buf[1]); /* WRITE PTRN FG */
+ put_unaligned_le64(lba, &buf[2]);
+ put_unaligned_le64(num, &buf[6]);
+ put_unaligned_le32(0u, &buf[10]); /* pattern */
+
+ WARN_ON(len > ATA_SCSI_RBUF_SIZE);

- put_unaligned_le16(0x0002, &sctpg[0]); /* SCT_ACT_WRITE_SAME */
- put_unaligned_le16(0x0101, &sctpg[1]); /* WRITE PTRN FG */
- put_unaligned_le64(lba, &sctpg[2]);
- put_unaligned_le64(num, &sctpg[6]);
- put_unaligned_le32(0u, &sctpg[10]);
+ if (len > ATA_SCSI_RBUF_SIZE)
+ len = ATA_SCSI_RBUF_SIZE;

- sg_copy_from_buffer(scsi_sglist(cmd), scsi_sg_count(cmd), sctpg, 512);
+ r = sg_copy_from_buffer(scsi_sglist(cmd), scsi_sg_count(cmd), buf, len);
spin_unlock_irqrestore(&ata_scsi_rbuf_lock, flags);
+
+ return r;
}

/**
@@ -3371,11 +3388,13 @@ static unsigned int ata_scsi_write_same_xlat(struct ata_queued_cmd *qc)
{
struct ata_taskfile *tf = &qc->tf;
struct scsi_cmnd *scmd = qc->scsicmd;
+ struct scsi_device *sdp = scmd->device;
+ size_t len = sdp->sector_size;
struct ata_device *dev = qc->dev;
const u8 *cdb = scmd->cmnd;
u64 block;
u32 n_block;
- const u32 trmax = ATA_MAX_TRIM_RNUM;
+ const u32 trmax = len >> 3;
u32 size;
u16 fp;
u8 bp = 0xff;
@@ -3420,8 +3439,16 @@ static unsigned int ata_scsi_write_same_xlat(struct ata_queued_cmd *qc)
if (!scsi_sg_count(scmd))
goto invalid_param_len;

+ /*
+ * size must match sector size in bytes
+ * For DATA SET MANAGEMENT TRIM in ACS-2 nsect (aka count)
+ * is defined as number of 512 byte blocks to be transferred.
+ */
if (unmap) {
size = ata_format_dsm_trim_descr(scmd, trmax, block, n_block);
+ if (size != len)
+ goto invalid_param_len;
+
if (ata_ncq_enabled(dev) && ata_fpdma_dsm_supported(dev)) {
/* Newer devices support queued TRIM commands */
tf->protocol = ATA_PROT_NCQ;
@@ -3441,7 +3468,9 @@ static unsigned int ata_scsi_write_same_xlat(struct ata_queued_cmd *qc)
tf->command = ATA_CMD_DSM;
}
} else {
- ata_format_sct_write_same(scmd, block, n_block);
+ size = ata_format_sct_write_same(scmd, block, n_block);
+ if (size != len)
+ goto invalid_param_len;

tf->hob_feature = 0;
tf->feature = 0;
--
2.9.3