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authorAlan Stern <stern@rowland.harvard.edu>2012-06-20 16:04:19 -0400
committerGreg Kroah-Hartman <gregkh@linuxfoundation.org>2012-07-16 09:04:10 -0700
commitb18504e4a631e31edd939fe569342274927d4b41 (patch)
tree86d9935b2829f36f4392cdd733cd1ff22c62cdaa /drivers/scsi
parent35733efe3599b30ace9b035eb425be85aaa3ae12 (diff)
SCSI & usb-storage: add try_rc_10_first flag
commit 6a0bdffa0073857870a4ed1b4489762146359eb4 upstream. 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> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Diffstat (limited to 'drivers/scsi')
-rw-r--r--drivers/scsi/sd.c2
1 files changed, 2 insertions, 0 deletions
diff --git a/drivers/scsi/sd.c b/drivers/scsi/sd.c
index 5ba5c2a9e8e9..a239382b2bdd 100644
--- a/drivers/scsi/sd.c
+++ b/drivers/scsi/sd.c
@@ -1898,6 +1898,8 @@ 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))