SCSI sg on 20190709
This topic branch covers a fundamental change in how our sg lists are
allocated to make mq more efficient by reducing the size of the
preallocated sg list. This necessitates a large number of driver
changes because the previous guarantee that if a driver specified
SG_ALL as the size of its scatter list, it would get a non-chained
list and didn't need to bother with scatterlist iterators is now
broken and every driver *must* use scatterlist iterators.
This was broken out as a separate topic because we need to convert all
the drivers before pulling the trigger and unconverted drivers kept
being found, necessitating a rebase.
Signed-off-by: James E.J. Bottomley <jejb@linux.ibm.com>
scsi: core: don't preallocate small SGL in case of NO_SG_CHAIN
The preallocated small SGL depends on SG_CHAIN so if the ARCH doesn't
support SG_CHAIN, preallocation of small SGL can't work at all.
Fix this issue by not using small preallocation in case of NO_SG_CHAIN.
Cc: Christoph Hellwig <hch@lst.de>
Cc: Bart Van Assche <bvanassche@acm.org>
Cc: Ewan D. Milne <emilne@redhat.com>
Cc: Hannes Reinecke <hare@suse.com>
Cc: Guenter Roeck <linux@roeck-us.net>
Reported-by: Guenter Roeck <linux@roeck-us.net>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Bart Van Assche <bvanassche@acm.org>
Tested-by: Guenter Roeck <linux@roeck-us.net>
Signed-off-by: Ming Lei <ming.lei@redhat.com>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>
1 file changed
