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From: Dave Chinner <david@fromorbit.com>
To: Christoph Hellwig <hch@lst.de>
Cc: rpeterso@redhat.com, linux-fsdevel@vger.kernel.org, xfs@oss.sgi.com
Subject: Re: iomap infrastructure and multipage writes V5
Date: Wed, 3 Aug 2016 09:42:47 +1000	[thread overview]
Message-ID: <20160802234247.GO16044@dastard> (raw)
In-Reply-To: <20160731191900.GA29301@lst.de>

On Sun, Jul 31, 2016 at 09:19:00PM +0200, Christoph Hellwig wrote:
> Now after spending this much time I've started wondering why we even
> reserve blocks in xfs_iomap_write_allocate - after all we've reserved
> space for the actual data blocks and the indlen worst case in
> xfs_bmapi_reserve_delalloc.  And in fact a little hack to drop that
> reservation seems to solve both the root cause (depleted reserved pool)
> and the cleanup mess.  I just haven't spend enought time to convince
> myself that it's actually safe, and in fact looking at the allocator
> makes me thing it only works by accident currently despite generally
> postive test results.
> 
> Here is the quick patch if anyone wants to chime in:
> 
> diff --git a/fs/xfs/xfs_iomap.c b/fs/xfs/xfs_iomap.c
> index 620fc91..67c317f 100644
> --- a/fs/xfs/xfs_iomap.c
> +++ b/fs/xfs/xfs_iomap.c
> @@ -717,7 +717,7 @@ xfs_iomap_write_allocate(
>  
>  		nimaps = 0;
>  		while (nimaps == 0) {
> -			nres = XFS_EXTENTADD_SPACE_RES(mp, XFS_DATA_FORK);
> +			nres = 0; // XFS_EXTENTADD_SPACE_RES(mp, XFS_DATA_FORK);
>  
>  			error = xfs_trans_alloc(mp, &M_RES(mp)->tr_write, nres,
>  					0, XFS_TRANS_RESERVE, &tp);
> 

This solves the problem for me, and from history appears to be the
right thing to do. Christoph, can you send a proper patch for this?

Cheers,

Dave.

-- 
Dave Chinner
david@fromorbit.com

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  parent reply	other threads:[~2016-08-02 23:42 UTC|newest]

Thread overview: 33+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2016-06-01 14:44 iomap infrastructure and multipage writes V5 Christoph Hellwig
2016-06-01 14:44 ` [PATCH 01/14] fs: move struct iomap from exportfs.h to a separate header Christoph Hellwig
2016-06-01 14:44 ` [PATCH 02/14] fs: introduce iomap infrastructure Christoph Hellwig
2016-06-16 16:12   ` Jan Kara
2016-06-17 12:01     ` Christoph Hellwig
2016-06-20  2:29       ` Dave Chinner
2016-06-20 12:22         ` Christoph Hellwig
2016-06-01 14:44 ` [PATCH 03/14] fs: support DAX based iomap zeroing Christoph Hellwig
2016-06-01 14:44 ` [PATCH 04/14] xfs: make xfs_bmbt_to_iomap available outside of xfs_pnfs.c Christoph Hellwig
2016-06-01 14:44 ` [PATCH 05/14] xfs: reorder zeroing and flushing sequence in truncate Christoph Hellwig
2016-06-01 14:44 ` [PATCH 06/14] xfs: implement iomap based buffered write path Christoph Hellwig
2016-06-01 14:44 ` [PATCH 07/14] xfs: remove buffered write support from __xfs_get_blocks Christoph Hellwig
2016-06-01 14:44 ` [PATCH 08/14] fs: iomap based fiemap implementation Christoph Hellwig
2016-08-18 13:18   ` Andreas Grünbacher
2016-06-01 14:44 ` [PATCH 09/14] xfs: use iomap " Christoph Hellwig
2016-06-01 14:44 ` [PATCH 10/14] xfs: use iomap infrastructure for DAX zeroing Christoph Hellwig
2016-06-01 14:44 ` [PATCH 11/14] xfs: handle 64-bit length in xfs_iozero Christoph Hellwig
2016-06-01 14:44 ` [PATCH 12/14] xfs: use xfs_zero_range in xfs_zero_eof Christoph Hellwig
2016-06-01 14:44 ` [PATCH 13/14] xfs: split xfs_free_file_space in manageable pieces Christoph Hellwig
2016-06-01 14:44 ` [PATCH 14/14] xfs: kill xfs_zero_remaining_bytes Christoph Hellwig
2016-06-01 14:46 ` iomap infrastructure and multipage writes V5 Christoph Hellwig
2016-06-28  0:26 ` Dave Chinner
2016-06-28 13:28   ` Christoph Hellwig
2016-06-28 13:38     ` Christoph Hellwig
2016-06-30 17:22   ` Christoph Hellwig
2016-06-30 23:16     ` Dave Chinner
2016-07-18 11:14     ` Dave Chinner
2016-07-18 11:18       ` Dave Chinner
2016-07-31 19:19         ` Christoph Hellwig
2016-08-01  0:16           ` Dave Chinner
2016-08-02 23:42           ` Dave Chinner [this message]
2016-07-19  3:50       ` Christoph Hellwig
  -- strict thread matches above, loose matches on Subject: below --
2017-02-13 22:32 xfs-owner

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