From 3a0a529971ec4e2d933e9c7798db101dfb6b1aec Mon Sep 17 00:00:00 2001 From: Bart Van Assche Date: Thu, 9 Nov 2017 10:49:58 -0800 Subject: block, scsi: Make SCSI quiesce and resume work reliably The contexts from which a SCSI device can be quiesced or resumed are: * Writing into /sys/class/scsi_device/*/device/state. * SCSI parallel (SPI) domain validation. * The SCSI device power management methods. See also scsi_bus_pm_ops. It is essential during suspend and resume that neither the filesystem state nor the filesystem metadata in RAM changes. This is why while the hibernation image is being written or restored that SCSI devices are quiesced. The SCSI core quiesces devices through scsi_device_quiesce() and scsi_device_resume(). In the SDEV_QUIESCE state execution of non-preempt requests is deferred. This is realized by returning BLKPREP_DEFER from inside scsi_prep_state_check() for quiesced SCSI devices. Avoid that a full queue prevents power management requests to be submitted by deferring allocation of non-preempt requests for devices in the quiesced state. This patch has been tested by running the following commands and by verifying that after each resume the fio job was still running: for ((i=0; i<10; i++)); do ( cd /sys/block/md0/md && while true; do [ "$( sync_action sleep 1 done ) & pids=($!) for d in /sys/class/block/sd*[a-z]; do bdev=${d#/sys/class/block/} hcil=$(readlink "$d/device") hcil=${hcil#../../../} echo 4 > "$d/queue/nr_requests" echo 1 > "/sys/class/scsi_device/$hcil/device/queue_depth" fio --name="$bdev" --filename="/dev/$bdev" --buffered=0 --bs=512 \ --rw=randread --ioengine=libaio --numjobs=4 --iodepth=16 \ --iodepth_batch=1 --thread --loops=$((2**31)) & pids+=($!) done sleep 1 echo "$(date) Hibernating ..." >>hibernate-test-log.txt systemctl hibernate sleep 10 kill "${pids[@]}" echo idle > /sys/block/md0/md/sync_action wait echo "$(date) Done." >>hibernate-test-log.txt done Reported-by: Oleksandr Natalenko References: "I/O hangs after resuming from suspend-to-ram" (https://marc.info/?l=linux-block&m=150340235201348). Signed-off-by: Bart Van Assche Reviewed-by: Hannes Reinecke Tested-by: Martin Steigerwald Tested-by: Oleksandr Natalenko Cc: Martin K. Petersen Cc: Ming Lei Cc: Christoph Hellwig Cc: Johannes Thumshirn Signed-off-by: Jens Axboe --- include/scsi/scsi_device.h | 1 + 1 file changed, 1 insertion(+) (limited to 'include/scsi/scsi_device.h') diff --git a/include/scsi/scsi_device.h b/include/scsi/scsi_device.h index 82e93ee94708..6f0f1e242e23 100644 --- a/include/scsi/scsi_device.h +++ b/include/scsi/scsi_device.h @@ -219,6 +219,7 @@ struct scsi_device { unsigned char access_state; struct mutex state_mutex; enum scsi_device_state sdev_state; + struct task_struct *quiesced_by; unsigned long sdev_data[0]; } __attribute__((aligned(sizeof(unsigned long)))); -- cgit v1.2.3-59-g8ed1b