From: "Darrick J. Wong" <darrick.wong@oracle.com>
To: Chandan Babu R <chandanrlinux@gmail.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: Thu, 15 Oct 2020 11:41:07 -0700 [thread overview]
Message-ID: <20201015184107.GB9832@magnolia> (raw)
In-Reply-To: <3688628.2sUYEX9xRT@garuda>
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. :/
--D
> >
>
> Ok. I will try to get this implemented.
>
> --
> chandan
>
>
>
next prev parent reply other threads:[~2020-10-15 18:41 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 [this message]
2020-10-16 11:31 ` Chandan Babu R
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