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From: Anand Jain <anand.jain@oracle.com>
To: dsterba@suse.cz, linux-btrfs@vger.kernel.org, quwenruo@cn.fujitsu.com
Subject: Re: [PATCH 2/4] btrfs: Communicate back ENOMEM when it occurs
Date: Wed, 29 Mar 2017 18:00:48 +0800	[thread overview]
Message-ID: <77251288-c6e6-cdd7-1a60-3cf3d46ee4d0@oracle.com> (raw)
In-Reply-To: <20170328153842.GA4781@twin.jikos.cz>



On 03/28/2017 11:38 PM, David Sterba wrote:
> On Mon, Mar 13, 2017 at 03:42:12PM +0800, Anand Jain wrote:
>> The only error that write dev flush (send) will fail is due
>> to the ENOMEM then, as its not a device specific error and
>> rather a system wide issue, we should rather stop further
>> iterations and perpetuate the -ENOMEM error to the caller.
>
> I think we should try harder, as flushing is a critical operation and a
> simple yet unlikely memory allocation failure should not stop it.
>
> The device::flush_bio is being allocated each time we start flush and
> freed afterwards. This seems unnecessary. The proper fix IMO is to
> preallocate the bio at the time the device is added to the list. The bio
> lifetime is same as the device'.


  I agree. Also as we are using an empty bio with
  the REQ_PREFLUSH flag we have the opportunity to use
  blkdev_issue_flush() instead. And bio is in fact
  does the prealloc part.
  Will use blkdev_issue_flush() and submit the patch
  again.

Thanks, Anand


  reply	other threads:[~2017-03-29  9:55 UTC|newest]

Thread overview: 22+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2017-03-13  7:42 [PATCH 0/4] cleanup barrier_all_devices() Anand Jain
2017-03-13  7:42 ` [PATCH 1/4] btrfs: REQ_PREFLUSH does not use btrfs_end_bio() completion callback Anand Jain
2017-03-28 15:19   ` David Sterba
2017-03-29 10:00     ` Anand Jain
2017-03-30 10:57       ` Anand Jain
2017-03-13  7:42 ` [PATCH 2/4] btrfs: Communicate back ENOMEM when it occurs Anand Jain
2017-03-14  8:49   ` Qu Wenruo
2017-03-28 15:38   ` David Sterba
2017-03-29 10:00     ` Anand Jain [this message]
2017-03-13  7:42 ` [PATCH 3/4] btrfs: cleanup barrier_all_devices() unify dev error count Anand Jain
2017-03-14  8:53   ` Qu Wenruo
2017-03-13  7:42 ` [PATCH 4/4] btrfs: cleanup barrier_all_devices() to check dev stat flush error Anand Jain
2017-03-13  9:05   ` Qu Wenruo
2017-03-13 16:21     ` Anand Jain
2017-03-14  0:28       ` Qu Wenruo
2017-03-14  3:36         ` Anand Jain
2017-03-14  8:26   ` [PATCH V2 " Anand Jain
2017-03-14  8:47     ` Qu Wenruo
2017-03-28 16:19     ` David Sterba
2017-03-29 10:00       ` Anand Jain
2017-03-31 11:36   ` [PATCH 4/4 V2] " Anand Jain
2017-04-05  4:07   ` [PATCH 4/4 V3] " Anand Jain

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