Hello.
On 05-07-2012 13:40, Paolo Bonzini wrote:
The cache_type file in sysfs lets users configure the disk cache in
write-through or write-back modes. However, ata disks do not support
writing to the file because they do not implement the MODE SELECT
command.
This patch adds a translation from MODE SELECT (for the caching page
only) to the ATA SET FEATURES command. The set of changeable parameters
answered by MODE SENSE is also adjusted accordingly.
Cc: Sergei Shtylyov <sshtylyov@xxxxxxxxxx>
Cc: Jeff Garzik <jgarzik@xxxxxxxxx>
Signed-off-by: Paolo Bonzini <pbonzini@xxxxxxxxxx>
---
drivers/ata/libata-scsi.c | 185 +++++++++++++++++++++++++++++++++++++++++++--
1 files changed, 179 insertions(+), 6 deletions(-)
diff --git a/drivers/ata/libata-scsi.c b/drivers/ata/libata-scsi.c
index d5aeb26..1cb88df 100644
--- a/drivers/ata/libata-scsi.c
+++ b/drivers/ata/libata-scsi.c
[...]
+/**
+ * ata_scsiop_mode_select - Simulate MODE SELECT 6, 10 commands
+ * @qc: Storage for translated ATA taskfile
+ *
+ * Converts a MODE SELECT command to an ATA SET FEATURES taskfile.
+ * Assume this is invoked for direct access devices (e.g. disks) only.
+ * There should be no block descriptor for other device types.
+ *
+ * LOCKING:
+ * spin_lock_irqsave(host lock)
+ */
+static unsigned int ata_scsi_mode_select_xlat(struct ata_queued_cmd *qc)
+{
+ struct scsi_cmnd *scmd = qc->scsicmd;
+ const u8 *cdb = scmd->cmnd;
+ const u8 *p;
+ u8 pg, spg;
+ unsigned six_byte, pg_len, hdr_len;
+ int len;
+
+ VPRINTK("ENTER\n");
+
+ six_byte = (cdb[0] == MODE_SELECT);
+ if (six_byte) {
+ if (scmd->cmd_len < 5)
+ goto invalid_fld;
Strictly speaking, it should be "invalid phase" error.
+
+ len = cdb[4];
+ } else {
+ if (scmd->cmd_len < 9)
+ goto invalid_fld;
The same.
+
+ len = (cdb[7] << 8) + cdb[8];
+ }
+ /* Test early for possible overrun. */
+ if (!scsi_sg_count(scmd) || scsi_sglist(scmd)->length < len)
+ goto invalid_param_len;
Strictly speaking, it's "data underrun" error.
+ p = page_address(sg_page(scsi_sglist(scmd)));
What if the S/G list spans multiple non-consecutive pages?
+
+ /* Move past header and block descriptors. */
+ if (six_byte)
+ hdr_len = p[3] + 4;
+ else
+ hdr_len = (p[6] << 8) + p[7] + 8;
+
+ if (len < hdr_len)
+ goto invalid_param_len;
+
+ len -= hdr_len;
+ p += hdr_len;
+ if (len == 0)
+ goto skip;
+
+ /* Parse both possible formats for the mode page headers. */
+ pg = p[0] & 0x3f;
+ if (p[0] & 0x40) {
+ if (len < 4)
+ goto invalid_param_len;
+
+ spg = p[1];
+ pg_len = (p[2] << 8) | p[3];
+ p += 4;
+ len -= 4;
+ } else {
+ if (len < 2)
+ goto invalid_param_len;
+
+ spg = 0;
+ pg_len = p[1];
+ p += 2;
+ len -= 2;
+ }
+
+ /*
+ * Only one page has changeable data, so we only support setting one
+ * page at a time.
+ */
+ if (len < pg_len)
+ goto invalid_param;
Not 'invalid_param_len'?
+
+ /*
+ * No mode subpages supported (yet) but asking for _all_
+ * subpages may be valid
+ */
+ if (spg && (spg != ALL_SUB_MPAGES))
+ goto invalid_param;
Rather "paramater not supported" (0x26/0x01)...
+ if (pg_len > len)
+ goto invalid_param_len;
We have just checked this.
+ switch (pg) {
+ case CACHE_MPAGE:
+ if (ata_mselect_caching(qc, p, pg_len) < 0)
+ goto invalid_param;
Rather "parameter not supported"?
+ break;
+
+ default: /* invalid page code */
+ goto invalid_param;
Rather "paramater not supported"...
+ }
+
+ return 0;
MBR, Sergei
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