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authorAlan Stern <stern@rowland.harvard.edu>2012-06-20 16:04:19 -0400
committerGreg Kroah-Hartman <gregkh@linuxfoundation.org>2012-06-22 22:05:31 -0700
commit6a0bdffa0073857870a4ed1b4489762146359eb4 (patch)
treead189d34420a54cdde107a936e5b10a371bc12ca /drivers/usb
parent1e2c4e59d2b8797973471b4a287a43eac12a0f40 (diff)
downloadlinux-6a0bdffa0073857870a4ed1b4489762146359eb4.tar.bz2
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/usb')
-rw-r--r--drivers/usb/storage/scsiglue.c6
1 files changed, 6 insertions, 0 deletions
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;