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From: Chandan Babu R <chandanrlinux@gmail.com>
To: "Darrick J. Wong" <darrick.wong@oracle.com>
Cc: Christoph Hellwig <hch@infradead.org>,
	linux-xfs@vger.kernel.org, david@fromorbit.com
Subject: Re: [PATCH V6 11/11] xfs: Introduce error injection to allocate only minlen size extents for files
Date: Fri, 16 Oct 2020 17:01:15 +0530	[thread overview]
Message-ID: <7126589.1pso20JOtx@garuda> (raw)
In-Reply-To: <20201015184107.GB9832@magnolia>

On Friday 16 October 2020 12:11:07 AM IST Darrick J. Wong wrote:
> On Thu, Oct 15, 2020 at 03:32:54PM +0530, Chandan Babu R wrote:
> > On Thursday 15 October 2020 2:11:10 PM IST Christoph Hellwig wrote:
> > > On Mon, Oct 12, 2020 at 02:59:38PM +0530, Chandan Babu R wrote:
> > > > This commit adds XFS_ERRTAG_BMAP_ALLOC_MINLEN_EXTENT error tag which
> > > > helps userspace test programs to get xfs_bmap_btalloc() to always
> > > > allocate minlen sized extents.
> > > > 
> > > > This is required for test programs which need a guarantee that minlen
> > > > extents allocated for a file do not get merged with their existing
> > > > neighbours in the inode's BMBT. "Inode fork extent overflow check" for
> > > > Directories, Xattrs and extension of realtime inodes need this since the
> > > > file offset at which the extents are being allocated cannot be
> > > > explicitly controlled from userspace.
> > > > 
> > > > One way to use this error tag is to,
> > > > 1. Consume all of the free space by sequentially writing to a file.
> > > > 2. Punch alternate blocks of the file. This causes CNTBT to contain
> > > >    sufficient number of one block sized extent records.
> > > > 3. Inject XFS_ERRTAG_BMAP_ALLOC_MINLEN_EXTENT error tag.
> > > > After step 3, xfs_bmap_btalloc() will issue space allocation
> > > > requests for minlen sized extents only.
> > > > 
> > > > ENOSPC error code is returned to userspace when there aren't any "one
> > > > block sized" extents left in any of the AGs.
> > > 
> > > Can we figure out a way to only build the extra code for debug kernels?
> 
> Yeah, I was gonna say that too.  You're basically installing a new
> allocator algorithm, but wow it scatters pieces of itself all over the
> place. :/

Right. I have almost completed refactoring the code into relevant functions. I
will execute the test suite and if everything goes well I will be posting the
next version of the patchset soon.

Thanks for the review comments.

-- 
chandan




      reply	other threads:[~2020-10-16 11:31 UTC|newest]

Thread overview: 32+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-10-12  9:29 [PATCH V6 00/11] Bail out if transaction can cause extent count to overflow Chandan Babu R
2020-10-12  9:29 ` [PATCH V6 01/11] xfs: Add helper for checking per-inode extent count overflow Chandan Babu R
2020-10-15  8:34   ` Christoph Hellwig
2020-10-12  9:29 ` [PATCH V6 02/11] xfs: Check for extent overflow when trivally adding a new extent Chandan Babu R
2020-10-15  8:34   ` Christoph Hellwig
2020-10-12  9:29 ` [PATCH V6 03/11] xfs: Check for extent overflow when punching a hole Chandan Babu R
2020-10-15  8:35   ` Christoph Hellwig
2020-10-12  9:29 ` [PATCH V6 04/11] xfs: Check for extent overflow when adding/removing xattrs Chandan Babu R
2020-10-15  8:36   ` Christoph Hellwig
2020-10-12  9:29 ` [PATCH V6 05/11] xfs: Check for extent overflow when adding/removing dir entries Chandan Babu R
2020-10-15  8:36   ` Christoph Hellwig
2020-10-12  9:29 ` [PATCH V6 06/11] xfs: Check for extent overflow when writing to unwritten extent Chandan Babu R
2020-10-15  8:36   ` Christoph Hellwig
2020-10-12  9:29 ` [PATCH V6 07/11] xfs: Check for extent overflow when moving extent from cow to data fork Chandan Babu R
2020-10-15  8:37   ` Christoph Hellwig
2020-10-12  9:29 ` [PATCH V6 08/11] xfs: Check for extent overflow when remapping an extent Chandan Babu R
2020-10-15  8:39   ` Christoph Hellwig
2020-10-15 10:01     ` Chandan Babu R
2020-10-15 18:45       ` Darrick J. Wong
2020-10-16  4:27         ` Chandan Babu R
2020-10-16  7:04       ` Christoph Hellwig
2020-10-16 11:28         ` Chandan Babu R
2020-10-16 15:29           ` Darrick J. Wong
2020-10-17  2:55             ` Chandan Babu R
2020-10-12  9:29 ` [PATCH V6 09/11] xfs: Check for extent overflow when swapping extents Chandan Babu R
2020-10-12  9:29 ` [PATCH V6 10/11] xfs: Introduce error injection to reduce maximum inode fork extent count Chandan Babu R
2020-10-15  8:40   ` Christoph Hellwig
2020-10-12  9:29 ` [PATCH V6 11/11] xfs: Introduce error injection to allocate only minlen size extents for files Chandan Babu R
2020-10-15  8:41   ` Christoph Hellwig
2020-10-15 10:02     ` Chandan Babu R
2020-10-15 18:41       ` Darrick J. Wong
2020-10-16 11:31         ` Chandan Babu R [this message]

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