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scsi: core: Reallocate device's budget map on queue depth change
We currently use ->cmd_per_lun as initial queue depth for setting up the budget_map. Martin Wilck reported that it is common for the queue_depth to be subsequently updated in slave_configure() based on detected hardware characteristics. As a result, for some drivers, the static host template settings for cmd_per_lun and can_queue won't actually get used in practice. And if the default values are used to allocate the budget_map, memory may be consumed unnecessarily. Fix the issue by reallocating the budget_map after ->slave_configure() returns. At that time the device queue_depth should accurately reflect what the hardware needs. Link: https://lore.kernel.org/r/20220127153733.409132-1-ming.lei@redhat.com Cc: Bart Van Assche <bvanassche@acm.org> Reported-by: Martin Wilck <martin.wilck@suse.com> Suggested-by: Martin Wilck <martin.wilck@suse.com> Tested-by: Martin Wilck <mwilck@suse.com> Reviewed-by: Martin Wilck <mwilck@suse.com> 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>
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1 changed files with 50 additions and 5 deletions
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@ -214,6 +214,48 @@ static void scsi_unlock_floptical(struct scsi_device *sdev,
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SCSI_TIMEOUT, 3, NULL);
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}
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static int scsi_realloc_sdev_budget_map(struct scsi_device *sdev,
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unsigned int depth)
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{
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int new_shift = sbitmap_calculate_shift(depth);
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bool need_alloc = !sdev->budget_map.map;
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bool need_free = false;
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int ret;
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struct sbitmap sb_backup;
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/*
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* realloc if new shift is calculated, which is caused by setting
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* up one new default queue depth after calling ->slave_configure
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*/
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if (!need_alloc && new_shift != sdev->budget_map.shift)
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need_alloc = need_free = true;
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if (!need_alloc)
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return 0;
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/*
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* Request queue has to be frozen for reallocating budget map,
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* and here disk isn't added yet, so freezing is pretty fast
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*/
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if (need_free) {
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blk_mq_freeze_queue(sdev->request_queue);
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sb_backup = sdev->budget_map;
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}
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ret = sbitmap_init_node(&sdev->budget_map,
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scsi_device_max_queue_depth(sdev),
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new_shift, GFP_KERNEL,
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sdev->request_queue->node, false, true);
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if (need_free) {
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if (ret)
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sdev->budget_map = sb_backup;
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else
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sbitmap_free(&sb_backup);
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ret = 0;
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blk_mq_unfreeze_queue(sdev->request_queue);
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}
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return ret;
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}
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/**
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* scsi_alloc_sdev - allocate and setup a scsi_Device
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* @starget: which target to allocate a &scsi_device for
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@ -306,11 +348,7 @@ static struct scsi_device *scsi_alloc_sdev(struct scsi_target *starget,
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* default device queue depth to figure out sbitmap shift
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* since we use this queue depth most of times.
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*/
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if (sbitmap_init_node(&sdev->budget_map,
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scsi_device_max_queue_depth(sdev),
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sbitmap_calculate_shift(depth),
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GFP_KERNEL, sdev->request_queue->node,
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false, true)) {
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if (scsi_realloc_sdev_budget_map(sdev, depth)) {
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put_device(&starget->dev);
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kfree(sdev);
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goto out;
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@ -1017,6 +1055,13 @@ static int scsi_add_lun(struct scsi_device *sdev, unsigned char *inq_result,
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}
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return SCSI_SCAN_NO_RESPONSE;
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}
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/*
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* The queue_depth is often changed in ->slave_configure.
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* Set up budget map again since memory consumption of
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* the map depends on actual queue depth.
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*/
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scsi_realloc_sdev_budget_map(sdev, sdev->queue_depth);
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}
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if (sdev->scsi_level >= SCSI_3)
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