From: Alan Stern Date: Wed, 20 Jun 2012 20:04:19 +0000 (-0400) Subject: SCSI & usb-storage: add try_rc_10_first flag X-Git-Tag: v3.5-rc5~18^2~6 X-Git-Url: http://git.openpandora.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=6a0bdffa0073857870a4ed1b4489762146359eb4;p=pandora-kernel.git 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 Acked-by: Hans de Goede CC: "James E.J. Bottomley" CC: Matthew Dharm Cc: stable Signed-off-by: Greg Kroah-Hartman --- Reading git-diff-tree failed