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>
3 files changed