linux-ext4 - Re: [PATCH v5 1/2] ext4: Discard preallocations before releasing group lock

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Date:   Thu, 24 Sep 2020 10:58:23 -0400
From:   "Theodore Y. Ts'o" <tytso@....edu>
To:     Ye Bin <yebin10@...wei.com>
Cc:     riteshh@...ux.ibm.com, jack@...e.cz, adilger.kernel@...ger.ca,
        jack@...e.com, linux-ext4@...r.kernel.org
Subject: Re: [PATCH v5 1/2] ext4: Discard preallocations before releasing
 group lock

On Wed, Sep 16, 2020 at 07:38:58PM +0800, Ye Bin wrote:
> From: Jan Kara <jack@...e.cz>
> 
> ext4_mb_discard_group_preallocations() can be releasing group lock with
> preallocations accumulated on its local list. Thus although
> discard_pa_seq was incremented and concurrent allocating processes will
> be retrying allocations, it can happen that premature ENOSPC error is
> returned because blocks used for preallocations are not available for
> reuse yet. Make sure we always free locally accumulated preallocations
> before releasing group lock.
> 
> Fixes: 07b5b8e1ac40 ("ext4: mballoc: introduce pcpu seqcnt for freeing PA to improve ENOSPC handling")
> Signed-off-by: Jan Kara <jack@...e.cz>
> Signed-off-by: Ye Bin <yebin10@...wei.com>
> Reviewed-by: Ritesh Harjani <riteshh@...ux.ibm.com>

Thanks, applied.

					- Ted