From: "Darrick J. Wong" <darrick.wong@oracle.com>
To: Christoph Hellwig <hch@lst.de>
Cc: Goldwyn Rodrigues <rgoldwyn@suse.com>,
linux-xfs@vger.kernel.org, linux-fsdevel@vger.kernel.org
Subject: Re: [PATCH 09/19] xfs: remove xfs_reflink_dirty_extents
Date: Wed, 18 Sep 2019 10:31:59 -0700 [thread overview]
Message-ID: <20190918173159.GD2229799@magnolia> (raw)
In-Reply-To: <20190918172545.GA19884@lst.de>
On Wed, Sep 18, 2019 at 07:25:45PM +0200, Christoph Hellwig wrote:
> On Wed, Sep 18, 2019 at 10:17:33AM -0700, Darrick J. Wong wrote:
> > > /*
> > > * Pre-COW all shared blocks within a given byte range of a file and turn off
> > > * the reflink flag if we unshare all of the file's blocks.
> > > + *
> > > + * Let iomap iterate all extents to see which are shared and not unwritten or
> > > + * delalloc and read them into the page cache, dirty them, fsync them back out,
> > > + * and then we can update the inode flag. What happens if we run out of
> > > + * memory? :)
> >
> > I don't know, what /does/ happen? :)
> >
> > It /should/ be fine, right? Writeback will start pushing the dirty
> > cache pages to disk, and since writeback only takes the ILOCK, it should
> > be able to perform the COW even while the unshare process sits on the
> > IOLOCK/MMAPLOCK. True, the unshare process and writeback will both be
> > contending on the ILOCK, but that shouldn't be a problem...
> >
> > ...unless I'm missing something? It sure does look nice to drain all
> > this other code out.
>
> No idea. This is your old code just moved down to this function. But
> yes, the comment looks rather confusing and maybe we should just remove
> it.
I know. I remember testing it way back in 4.9 when we first merged it
to make sure it really did work that way, and I think the locking model
hasn't changed so it should be fine. But just wanted another set of
eyes to make sure things haven't subtlely shifted since then. :)
--D
next prev parent reply other threads:[~2019-09-18 17:32 UTC|newest]
Thread overview: 54+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-09-09 18:27 iomap and xfs COW cleanups Christoph Hellwig
2019-09-09 18:27 ` [PATCH 01/19] iomap: better document the IOMAP_F_* flags Christoph Hellwig
2019-09-14 0:42 ` Allison Collins
2019-09-16 18:08 ` Darrick J. Wong
2019-09-09 18:27 ` [PATCH 02/19] iomap: remove the unused iomap argument to __iomap_write_end Christoph Hellwig
2019-09-14 0:42 ` Allison Collins
2019-09-16 18:10 ` Darrick J. Wong
2019-09-09 18:27 ` [PATCH 03/19] iomap: always use AOP_FLAG_NOFS in iomap_write_begin Christoph Hellwig
2019-09-16 18:11 ` Darrick J. Wong
2019-09-09 18:27 ` [PATCH 04/19] iomap: ignore non-shared or non-data blocks in xfs_file_dirty Christoph Hellwig
2019-09-16 18:12 ` Darrick J. Wong
2019-09-09 18:27 ` [PATCH 05/19] iomap: move the zeroing case out of iomap_read_page_sync Christoph Hellwig
2019-09-16 18:17 ` Darrick J. Wong
2019-09-09 18:27 ` [PATCH 06/19] iomap: use write_begin to read pages to unshare Christoph Hellwig
2019-09-16 18:34 ` Darrick J. Wong
2019-09-30 11:07 ` Christoph Hellwig
2019-10-08 15:12 ` Darrick J. Wong
2019-09-09 18:27 ` [PATCH 07/19] iomap: use a srcmap for a read-modify-write I/O Christoph Hellwig
2019-09-10 12:48 ` Goldwyn Rodrigues
2019-09-10 14:39 ` hch
2019-09-16 17:57 ` Darrick J. Wong
2019-09-16 18:42 ` Darrick J. Wong
2019-09-18 18:15 ` Darrick J. Wong
2019-09-09 18:27 ` [PATCH 08/19] xfs: also call xfs_file_iomap_end_delalloc for zeroing operations Christoph Hellwig
2019-09-18 17:09 ` Darrick J. Wong
2019-09-09 18:27 ` [PATCH 09/19] xfs: remove xfs_reflink_dirty_extents Christoph Hellwig
2019-09-18 17:17 ` Darrick J. Wong
2019-09-18 17:25 ` Christoph Hellwig
2019-09-18 17:31 ` Darrick J. Wong [this message]
2019-09-09 18:27 ` [PATCH 10/19] xfs: pass two imaps to xfs_reflink_allocate_cow Christoph Hellwig
2019-09-18 17:26 ` Darrick J. Wong
2019-09-30 11:10 ` Christoph Hellwig
2019-09-09 18:27 ` [PATCH 11/19] xfs: refactor xfs_file_iomap_begin_delay Christoph Hellwig
2019-09-18 17:30 ` Darrick J. Wong
2019-09-09 18:27 ` [PATCH 12/19] xfs: fill out the srcmap in iomap_begin Christoph Hellwig
2019-09-18 17:52 ` Darrick J. Wong
2019-10-01 6:26 ` Christoph Hellwig
2019-09-09 18:27 ` [PATCH 13/19] xfs: factor out a helper to calculate the end_fsb Christoph Hellwig
2019-09-14 0:42 ` Allison Collins
2019-09-18 17:55 ` Darrick J. Wong
2019-09-09 18:27 ` [PATCH 14/19] xfs: split out a new set of read-only iomap ops Christoph Hellwig
2019-09-18 17:56 ` Darrick J. Wong
2019-09-09 18:27 ` [PATCH 15/19] xfs: move xfs_file_iomap_begin_delay around Christoph Hellwig
2019-09-18 17:59 ` Darrick J. Wong
2019-09-30 11:14 ` Christoph Hellwig
2019-09-09 18:27 ` [PATCH 16/19] xfs: split the iomap ops for buffered vs direct writes Christoph Hellwig
2019-09-18 18:00 ` Darrick J. Wong
2019-09-09 18:27 ` [PATCH 17/19] xfs: rename the whichfork variable in xfs_buffered_write_iomap_begin Christoph Hellwig
2019-09-14 0:42 ` Allison Collins
2019-09-18 18:00 ` Darrick J. Wong
2019-09-09 18:27 ` [PATCH 18/19] xfs: cleanup xfs_iomap_write_unwritten Christoph Hellwig
2019-09-18 18:06 ` Darrick J. Wong
2019-09-09 18:27 ` [PATCH 19/19] xfs: improve the IOMAP_NOWAIT check for COW inodes Christoph Hellwig
2019-09-18 18:09 ` Darrick J. Wong
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=20190918173159.GD2229799@magnolia \
--to=darrick.wong@oracle.com \
--cc=hch@lst.de \
--cc=linux-fsdevel@vger.kernel.org \
--cc=linux-xfs@vger.kernel.org \
--cc=rgoldwyn@suse.com \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).