• Nicholas Bellinger's avatar
    target: Drop arbitrary maximum I/O size limit · 046ba642
    Nicholas Bellinger authored
    This patch drops the arbitrary maximum I/O size limit in sbc_parse_cdb(),
    which currently for fabric_max_sectors is hardcoded to 8192 (4 MB for 512
    byte sector devices), and for hw_max_sectors is a backend driver dependent
    value.
    
    This limit is problematic because Linux initiators have only recently
    started to honor block limits MAXIMUM TRANSFER LENGTH, and other non-Linux
    based initiators (eg: MSFT Fibre Channel) can also generate I/Os larger
    than 4 MB in size.
    
    Currently when this happens, the following message will appear on the
    target resulting in I/Os being returned with non recoverable status:
    
      SCSI OP 28h with too big sectors 16384 exceeds fabric_max_sectors: 8192
    
    Instead, drop both [fabric,hw]_max_sector checks in sbc_parse_cdb(),
    and convert the existing hw_max_sectors into a purely informational
    attribute used to represent the granuality that backend driver and/or
    subsystem code is splitting I/Os upon.
    
    Also, update FILEIO with an explicit FD_MAX_BYTES check in fd_execute_rw()
    to deal with the one special iovec limitiation case.
    
    v2 changes:
      - Drop hw_max_sectors check in sbc_parse_cdb()
    Reported-by: default avatarLance Gropper <lance.gropper@qosserver.com>
    Reported-by: default avatarStefan Priebe <s.priebe@profihost.ag>
    Cc: Christoph Hellwig <hch@lst.de>
    Cc: Martin K. Petersen <martin.petersen@oracle.com>
    Cc: Roland Dreier <roland@purestorage.com>
    Cc: stable@vger.kernel.org # 3.4
    Signed-off-by: default avatarNicholas Bellinger <nab@linux-iscsi.org>
    046ba642
target_core_device.c 45.7 KB