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

Hannes Reinecke
2016-08-22T06:31:00Z

On 08/22/2016 06:23 AM, Shaun Tancheff wrote:
> Correct handling of devices with sector_size other that 512 bytes.
>
> Signed-off-by: Shaun Tancheff <shaun.tancheff@seagate.com>
> ---
> 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.
>
Can you please reshuffle the description to have the 'Signed-off-by'
line following the entire description?
This makes things easier to read and avoid the last part of the
description being killed by overzealous patch programs.
THX.

> v5:
> - 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;
>
Why is this not folded into the previous patches?
This mostly patches code which you've already modified and/or initiated,
right?

Cheers,

Hannes
--
Dr. Hannes Reinecke Teamlead Storage & Networking
hare@suse.de +49 911 74053 688
SUSE LINUX GmbH, Maxfeldstr. 5, 90409 Nürnberg
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