Set the allocation length to 255 for the ATA Information VPD page
requested in the WRITE SAME handler, so as not to limit information
examined by `scsi_get_vpd_page' in the supported vital product data
pages unnecessarily.
Originally it was thought that Areca hardware may have issues with a
valid allocation length supplied for a VPD inquiry, however older SCSI
standard revisions[1] consider 255 the maximum length allowed and what
has later become the high order byte is considered reserved and must be
zero with the INQUIRY command. Therefore it was unnecessary to reduce
the amount of data requested from 512 as far down as to 64, arbitrarily
chosen, and 255 would as well do.
With commit b3ae8780b429 ("[SCSI] Add EVPD page 0x83 and 0x80 to sysfs")
we have since got the SCSI_VPD_PG_LEN macro, so use that instead.
References:
[1] "Information technology - Small Computer System Interface - 2",
WORKING DRAFT, X3T9.2, Project 375D, Revision 10L, 7-SEP-93, Section
8.2.5 "INQUIRY command", pp.104-108
Signed-off-by: Maciej W. Rozycki <macro@xxxxxxxxxxx>
Fixes: af73623f5f10 ("[SCSI] sd: Reduce buffer size for vpd request")
---
Nix,
I can see you're still around. Would you therefore please be so kind
as to verify this change with your Areca hardware if you still have it?
It looks to me like you were thinking in the right direction with:
<https://lore.kernel.org/linux-scsi/87vc3nuipg.fsf@xxxxxxxxxxxxxxxx/>.
Sadly nobody seemed to have paid attention to your observation and neither
were different buffer sizes considered (or at least it wasn't mentioned in
the discussion).
Maciej
---
drivers/scsi/sd.c | 5 +----
1 file changed, 1 insertion(+), 4 deletions(-)
linux-scsi-write-same-vpd-buffer.diff
Index: linux-macro-ide/drivers/scsi/sd.c
===================================================================
--- linux-macro-ide.orig/drivers/scsi/sd.c
+++ linux-macro-ide/drivers/scsi/sd.c
@@ -3076,16 +3076,13 @@ static void sd_read_write_same(struct sc
}
if (scsi_report_opcode(sdev, buffer, SD_BUF_SIZE, INQUIRY) < 0) {
- /* too large values might cause issues with arcmsr */
- int vpd_buf_len = 64;
-
sdev->no_report_opcodes = 1;
/* Disable WRITE SAME if REPORT SUPPORTED OPERATION
* CODES is unsupported and the device has an ATA
* Information VPD page (SAT).
*/
- if (!scsi_get_vpd_page(sdev, 0x89, buffer, vpd_buf_len))
+ if (!scsi_get_vpd_page(sdev, 0x89, buffer, SCSI_VPD_PG_LEN))
sdev->no_write_same = 1;
}
