[PATCH 0/2] scsi/libata: A potential tagging fix and improvement

John Garry
2022-03-15T10:49:28Z

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(-)

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2.26.2