diff options
| author | Alan Stern | 2012-06-20 16:04:19 -0400 |
|---|---|---|
| committer | Greg Kroah-Hartman | 2012-06-22 22:05:31 -0700 |
| commit | 6a0bdffa0073857870a4ed1b4489762146359eb4 (patch) | |
| tree | ad189d34420a54cdde107a936e5b10a371bc12ca /drivers | |
| parent | 1e2c4e59d2b8797973471b4a287a43eac12a0f40 (diff) | |
SCSI & usb-storage: add try_rc_10_first flag
Several bug reports have been received recently for USB mass-storage
devices that don't handle READ CAPACITY(16) commands properly. They
report bogus sizes, in some cases becoming unusable as a result.
The bugs were triggered by commit
09b6b51b0b6c1b9bb61815baf205e4d74c89ff04 (SCSI & usb-storage: add
flags for VPD pages and REPORT LUNS), which caused usb-storage to stop
overriding the SCSI level reported by devices. By default, the sd
driver will try READ CAPACITY(16) first for any device whose level is
above SCSI_SPC_2.
It seems likely that any device large enough to require the use of
READ CAPACITY(16) (i.e., 2 TB or more) would be able to handle READ
CAPACITY(10) commands properly. Indeed, I don't know of any devices
that don't handle READ CAPACITY(10) properly.
Therefore this patch (as1559) adds a new flag telling the sd driver
to try READ CAPACITY(10) before READ CAPACITY(16), and sets this flag
for every USB mass-storage device. If a device really is larger than
2 TB, sd will fall back to READ CAPACITY(16) just as it used to.
This fixes Bugzilla #43391.
Signed-off-by: Alan Stern <stern@rowland.harvard.edu>
Acked-by: Hans de Goede <hdegoede@redhat.com>
CC: "James E.J. Bottomley" <JBottomley@parallels.com>
CC: Matthew Dharm <mdharm-usb@one-eyed-alien.net>
Cc: stable <stable@vger.kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Diffstat (limited to 'drivers')
| -rw-r--r-- | drivers/scsi/sd.c | 2 | ||||
| -rw-r--r-- | drivers/usb/storage/scsiglue.c | 6 |
2 files changed, 8 insertions, 0 deletions
diff --git a/drivers/scsi/sd.c b/drivers/scsi/sd.c index 6f0a4c612b3b..6f72b80121a0 100644 --- a/drivers/scsi/sd.c +++ b/drivers/scsi/sd.c @@ -1899,6 +1899,8 @@ static int sd_try_rc16_first(struct scsi_device *sdp) { if (sdp->host->max_cmd_len < 16) return 0; + if (sdp->try_rc_10_first) + return 0; if (sdp->scsi_level > SCSI_SPC_2) return 1; if (scsi_device_protection(sdp)) diff --git a/drivers/usb/storage/scsiglue.c b/drivers/usb/storage/scsiglue.c index a324a5d21e99..11418da9bc09 100644 --- a/drivers/usb/storage/scsiglue.c +++ b/drivers/usb/storage/scsiglue.c @@ -202,6 +202,12 @@ static int slave_configure(struct scsi_device *sdev) if (us->fflags & US_FL_NO_READ_CAPACITY_16) sdev->no_read_capacity_16 = 1; + /* + * Many devices do not respond properly to READ_CAPACITY_16. + * Tell the SCSI layer to try READ_CAPACITY_10 first. + */ + sdev->try_rc_10_first = 1; + /* assume SPC3 or latter devices support sense size > 18 */ if (sdev->scsi_level > SCSI_SPC_2) us->fflags |= US_FL_SANE_SENSE; |