tree 304851d932a594759898f98b01757ca96c78b1ef
parent da5567369fb686eb050da15364f11ef561f9a03e
author Ming Lei <ming.lei@redhat.com> 1560821871 +0800
committer Martin K. Petersen <martin.petersen@oracle.com> 1561058493 -0400

scsi: s390: zfcp_fc: use sg helper to iterate over scatterlist

Unlike the legacy I/O path, scsi-mq preallocates a large array to hold
the scatterlist for each request. This static allocation can consume
substantial amounts of memory on modern controllers which support a
large number of concurrently outstanding requests.

To facilitate a switch to a smaller static allocation combined with a
dynamic allocation for requests that need it, we need to make sure all
SCSI drivers handle chained scatterlists correctly.

Convert remaining drivers that directly dereference the scatterlist
array to using the iterator functions.

[mkp: clarified commit message]

Cc: Steffen Maier <maier@linux.ibm.com>
Cc: Benjamin Block <bblock@linux.ibm.com>
Cc: Martin Schwidefsky <schwidefsky@de.ibm.com>
Cc: Heiko Carstens <heiko.carstens@de.ibm.com>
Cc: linux-s390@vger.kernel.org
Acked-by: Benjamin Block <bblock@linux.ibm.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Bart Van Assche <bvanassche@acm.org>
Signed-off-by: Ming Lei <ming.lei@redhat.com>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>