• Alan Stern's avatar
    usb-storage: use max_hw_sectors instead of max_sectors · 49d6271b
    Alan Stern authored
    This patch (as1347) makes some adjustments to the way usb-storage
    handles the request-queue parameters.
    
    USB host controllers are able to handle arbitrarily long
    scatter-gather lists, since they are limited only by main memory and
    not by the controller hardware.  Hence the sg_tablesize field in the
    host template can be increased to the maximum value.
    
    Drivers like usb-storage aren't supposed to touch the queue's
    max_sectors parameter; instead they are supposed to use the
    max_hw_sectors value.  Accordingly, the patch replaces calls of
    queue_max_sectors() with calls of queue_max_hw_sectors().  Oddly
    enough, the blk_queue_max_sectors() routine is nevertheless still
    appropriate.
    
    The existing code imposes a limit of SCSI_DEFAULT_MAX_SECTORS (1024)
    on the values accepted by the max_sectors attribute file.  There's no
    reason not to accept larger values, so the limit is removed.  (It
    would be nice to change the file's name to max_hw_sectors, but the old
    name is already a well-established API.)
    Signed-off-by: default avatarAlan Stern <stern@rowland.harvard.edu>
    CC: Matthew Dharm <mdharm-usb@one-eyed-alien.net>
    Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@suse.de>
    49d6271b
scsiglue.c 18.2 KB