From: Hannes Reinecke <hare@suse.de>
To: Bart Van Assche <bart.vanassche@sandisk.com>,
"Martin K. Petersen" <martin.petersen@oracle.com>
Cc: Christoph Hellwig <hch@lst.de>, Ewan Milne <emilne@redhat.com>,
James Bottomley <james.bottomley@hansenpartnership.com>,
"linux-scsi@vger.kernel.org" <linux-scsi@vger.kernel.org>
Subject: Re: [PATCHv8 20/23] scsi: Add 'access_state' attribute
Date: Sun, 21 Feb 2016 09:27:55 +0100 [thread overview]
Message-ID: <56C9750B.9010200@suse.de> (raw)
In-Reply-To: <56C8834F.50304@sandisk.com>
On 02/20/2016 04:16 PM, Bart Van Assche wrote:
> On 02/20/16 00:03, Hannes Reinecke wrote:
>> Also when using your suggestion the 'access_state' attribute will only
>> be created _after_ the 'ADD' uevent, making it impossible to use it from
>> udev events.
>
> Can you give an example in which it would be useful to read the ALUA
> state from a udev handler ? I'm not sure such an example exists.
>
When evaluating the 'access_state' from an uevent we can avoid sending
I/O if the path is unavailable; eg if the path is in 'transitioning' I/O
will be queued until that path becomes available again.
Which means that the uevent will be delayed during udev processing, so
that the event will never be read by multipathing (as it's being invoked
only after udev event processing has finished).
And in extreme cases (like OnTap takeover/giveback) it will even drop
the event completely due to a timeout.
>> If you're absolutely against it we can drop the 'access_state' patches
>> (ie patch 20-22) and have them folded into a separate patchset.
>
> That sounds like a good idea to me.
>
Ok, let's do this.
Martin, can you please ignore patches 20-22 when pulling the patchset?
I'll be resubmitting a new patchset with them once these issues are
sorted out.
Or do you need a new patch submission?
Cheers,
Hannes
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Dr. Hannes Reinecke zSeries & Storage
hare@suse.de +49 911 74053 688
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next prev parent reply other threads:[~2016-02-21 17:23 UTC|newest]
Thread overview: 35+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-02-19 8:16 [PATCHv8 00/23] ALUA device handler update, part II Hannes Reinecke
2016-02-19 8:16 ` [PATCHv8 01/23] scsi_dh_alua: Pass buffer as function argument Hannes Reinecke
2016-02-19 8:16 ` [PATCHv8 02/23] scsi_dh_alua: separate out alua_stpg() Hannes Reinecke
2016-02-19 8:17 ` [PATCHv8 03/23] scsi_dh_alua: Make stpg synchronous Hannes Reinecke
2016-02-19 8:17 ` [PATCHv8 04/23] scsi_dh_alua: call alua_rtpg() if stpg fails Hannes Reinecke
2016-02-19 8:17 ` [PATCHv8 05/23] scsi_dh_alua: switch to scsi_execute_req_flags() Hannes Reinecke
2016-02-19 8:17 ` [PATCHv8 06/23] scsi_dh_alua: allocate RTPG buffer separately Hannes Reinecke
2016-02-19 8:17 ` [PATCHv8 07/23] scsi_dh_alua: Use separate alua_port_group structure Hannes Reinecke
2016-02-19 8:17 ` [PATCHv8 08/23] scsi_dh_alua: use unique device id Hannes Reinecke
2016-02-19 8:17 ` [PATCHv8 09/23] scsi_dh_alua: simplify alua_initialize() Hannes Reinecke
2016-02-19 8:17 ` [PATCHv8 10/23] revert commit a8e5a2d593cb ("[SCSI] scsi_dh_alua: ALUA handler attach should succeed while TPG is transitioning") Hannes Reinecke
2016-02-19 8:17 ` [PATCHv8 11/23] scsi_dh_alua: move optimize_stpg evaluation Hannes Reinecke
2016-02-19 8:17 ` [PATCHv8 12/23] scsi_dh_alua: remove 'rel_port' from alua_dh_data structure Hannes Reinecke
2016-02-19 8:17 ` [PATCHv8 13/23] scsi_dh_alua: Use workqueue for RTPG Hannes Reinecke
2016-02-19 8:17 ` [PATCHv8 14/23] scsi_dh_alua: Allow workqueue to run synchronously Hannes Reinecke
2016-02-19 8:17 ` [PATCHv8 15/23] scsi_dh_alua: Add new blacklist flag 'BLIST_SYNC_ALUA' Hannes Reinecke
2016-02-19 8:17 ` [PATCHv8 16/23] scsi_dh_alua: Recheck state on unit attention Hannes Reinecke
2016-02-19 8:17 ` [PATCHv8 17/23] scsi_dh_alua: update all port states Hannes Reinecke
2016-02-19 8:17 ` [PATCHv8 18/23] scsi_dh_alua: Send TEST UNIT READY to poll for transitioning Hannes Reinecke
2016-02-19 8:17 ` [PATCHv8 19/23] scsi_dh: add 'rescan' callback Hannes Reinecke
2016-02-19 8:17 ` [PATCHv8 20/23] scsi: Add 'access_state' attribute Hannes Reinecke
2016-02-19 19:10 ` Bart Van Assche
2016-02-20 8:03 ` Hannes Reinecke
2016-02-20 15:16 ` Bart Van Assche
2016-02-21 8:27 ` Hannes Reinecke [this message]
2016-02-22 3:05 ` Martin K. Petersen
2016-02-22 4:45 ` Bart Van Assche
2016-02-22 6:59 ` Hannes Reinecke
2016-02-22 15:34 ` Bart Van Assche
2016-02-23 10:27 ` Hannes Reinecke
2016-02-23 14:12 ` Ewan Milne
2016-02-19 8:17 ` [PATCHv8 21/23] scsi_dh_alua: use common definitions for ALUA state Hannes Reinecke
2016-02-19 8:17 ` [PATCHv8 22/23] scsi_dh_alua: update 'access_state' field Hannes Reinecke
2016-02-19 8:17 ` [PATCHv8 23/23] scsi_dh_alua: Update version to 2.0 Hannes Reinecke
2016-02-24 1:50 ` [PATCHv8 00/23] ALUA device handler update, part II Martin K. Petersen
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