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From:   John Garry <john.garry@huawei.com>
To:     <damien.lemoal@opensource.wdc.com>, <jejb@linux.ibm.com>,
        <martin.petersen@oracle.com>, <bvanassche@acm.org>,
        <ming.lei@redhat.com>, <hch@lst.de>, <hare@suse.de>
CC:     <linux-ide@vger.kernel.org>, <linux-kernel@vger.kernel.org>,
        <linux-scsi@vger.kernel.org>, <martin.wilck@suse.com>,
        John Garry <john.garry@huawei.com>
Subject: [PATCH 0/2] scsi/libata: A potential tagging fix and improvement
Date:   Tue, 15 Mar 2022 18:39:04 +0800
Message-ID: <1647340746-17600-1-git-send-email-john.garry@huawei.com>
MIME-Version: 1.0
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Two loosely related patches are included:

- Fix for scsi_realloc_sdev_budget_map(). I noticed that the budget token
  for scsi commands was way in excess of the device queue depth, so I
  think we need to fix the sbitmap depth. I need to test this more.

- libata change to use scsi command budget token for qc tag for SAS host.
  I marked this as RFC as for SAS hosts I don't see anything which
  guarantees that the budget size is <= 32 always.
  For libsas hosts we resize the device depth to 32 in the slave configure
  callback, but this seems an unreliable approach since not all hosts may
  call this.
  In addition, I am worried that even if we resize the device depth
  properly in the slave config callback, we may still try to alloc qc tag
  prior to this - in lun scan, for example.
  So we need a way to guarantee that the device queue depth is <= 32
  always, which I would be open to suggestions for.

John Garry (2):
  scsi: core: Fix sbitmap depth in scsi_realloc_sdev_budget_map()
  libata: Use scsi cmnd budget token for qc tag for SAS host

 drivers/ata/libata-core.c |  5 +++--
 drivers/ata/libata-sata.c | 21 ++++-----------------
 drivers/ata/libata-scsi.c |  2 +-
 drivers/ata/libata.h      |  4 ++--
 drivers/scsi/scsi_scan.c  |  5 +++++
 include/linux/libata.h    |  1 -
 6 files changed, 15 insertions(+), 23 deletions(-)

-- 
2.26.2