libata: SCT Write Same / DSM Trim

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>
Acked-by: Tejun Heo <tj@kernel.org>

1 files changed, 57 insertions, 28 deletions

diff --git a/drivers/ata/libata-scsi.c b/drivers/ata/libata-scsi.c
index 08d9c8e731b3..35b1f9e475cc 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;