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scsi: core: alua: I/O errors for ALUA state transitions
[ Upstream commit 10157b1 ] When a host is configured with a few LUNs and I/O is running, injecting FC faults repeatedly leads to path recovery problems. The LUNs have 4 paths each and 3 of them come back active after say an FC fault which makes 2 of the paths go down, instead of all 4. This happens after several iterations of continuous FC faults. Reason here is that we're returning an I/O error whenever we're encountering sense code 06/04/0a (LOGICAL UNIT NOT ACCESSIBLE, ASYMMETRIC ACCESS STATE TRANSITION) instead of retrying. [mwilck: The original patch was developed by Rajashekhar M A and Hannes Reinecke. I moved the code to alua_check_sense() as suggested by Mike Christie [1]. Evan Milne had raised the question whether pg->state should be set to transitioning in the UA case [2]. I believe that doing this is correct. SCSI_ACCESS_STATE_TRANSITIONING by itself doesn't cause I/O errors. Our handler schedules an RTPG, which will only result in an I/O error condition if the transitioning timeout expires.] [1] https://lore.kernel.org/all/[email protected]/ [2] https://lore.kernel.org/all/CAGtn9r=kicnTDE2o7Gt5Y=yoidHYD7tG8XdMHEBJTBraVEoOCw@mail.gmail.com/ Co-developed-by: Rajashekhar M A <[email protected]> Co-developed-by: Hannes Reinecke <[email protected]> Signed-off-by: Hannes Reinecke <[email protected]> Signed-off-by: Martin Wilck <[email protected]> Link: https://lore.kernel.org/r/[email protected] Reviewed-by: Damien Le Moal <[email protected]> Reviewed-by: Christoph Hellwig <[email protected]> Reviewed-by: Mike Christie <[email protected]> Signed-off-by: Martin K. Petersen <[email protected]> Signed-off-by: Sasha Levin <[email protected]>
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