From: Matthew Wilcox <matthew@xxxxxx>
New features are being added to the READ CAPACITY 16 results, so we
want to issue it in preference to READ CAPACITY 10. Unfortunately, some
devices misbehave when they see a READ CAPACITY 16, so we restrict this
command to devices which claim conformance to SPC-3 (aka SBC-2), or claim
they have features which are only reported in the READ CAPACITY 16 data.
The READ CAPACITY 16 command is optional, even for SBC-2 devices, so
we fall back to READ CAPACITY 10 if READ CAPACITY 16 fails.
Signed-off-by: Matthew Wilcox <willy@xxxxxxxxxxxxxxx>
Tested-by: Martin K. Petersen <martin.petersen@xxxxxxxxxx>
---
drivers/scsi/sd.c | 16 ++++++++++++++--
1 files changed, 14 insertions(+), 2 deletions(-)
diff --git a/drivers/scsi/sd.c b/drivers/scsi/sd.c
index 6cf0c25..b155488 100644
--- a/drivers/scsi/sd.c
+++ b/drivers/scsi/sd.c
@@ -1418,6 +1418,15 @@ static int read_capacity_10(struct scsi_disk *sdkp, struct scsi_device *sdp,
return sector_size;
}
+static int sd_try_rc16_first(struct scsi_device *sdp)
+{
+ if (sdp->scsi_level > SCSI_SPC_2)
+ return 1;
+ if (scsi_device_protection(sdp))
+ return 1;
+ return 0;
+}
+
/*
* read disk capacity
*/
@@ -1427,11 +1436,14 @@ sd_read_capacity(struct scsi_disk *sdkp, unsigned char *buffer)
int sector_size;
struct scsi_device *sdp = sdkp->device;
- /* Force READ CAPACITY(16) when PROTECT=1 */
- if (scsi_device_protection(sdp)) {
+ if (sd_try_rc16_first(sdp)) {
sector_size = read_capacity_16(sdkp, sdp, buffer);
if (sector_size == -EOVERFLOW)
goto got_data;
+ if (sector_size == -ENODEV)
+ return;
+ if (sector_size < 0)
+ sector_size = read_capacity_10(sdkp, sdp, buffer);
if (sector_size < 0)
return;
} else {
--
1.6.1.3
--
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