• Alan Stern's avatar
    SCSI & usb-storage: add try_rc_10_first flag · 6a0bdffa
    Alan Stern authored
    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
    09b6b51b (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: default avatarAlan Stern <stern@rowland.harvard.edu>
    Acked-by: default avatarHans 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: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
sd.c 78.7 KB