From: "Darrick J. Wong" <darrick.wong@oracle.com>
To: Chandan Babu R <chandanrlinux@gmail.com>
Cc: linux-xfs@vger.kernel.org, david@fromorbit.com, hch@infradead.org
Subject: Re: [PATCH V3 08/10] xfs: Check for extent overflow when moving extent from cow to data fork
Date: Mon, 31 Aug 2020 09:29:08 -0700 [thread overview]
Message-ID: <20200831162908.GK6096@magnolia> (raw)
In-Reply-To: <20200820054349.5525-9-chandanrlinux@gmail.com>
On Thu, Aug 20, 2020 at 11:13:47AM +0530, Chandan Babu R wrote:
> Moving an extent to data fork can cause a sub-interval of an existing
> extent to be unmapped. This will increase extent count by 1. Mapping in
> the new extent can increase the extent count by 1 again i.e.
> | Old extent | New extent | Old extent |
> Hence number of extents increases by 2.
>
> Signed-off-by: Chandan Babu R <chandanrlinux@gmail.com>
> ---
> fs/xfs/libxfs/xfs_inode_fork.h | 9 ++++++++-
> fs/xfs/xfs_reflink.c | 5 +++++
> 2 files changed, 13 insertions(+), 1 deletion(-)
>
> diff --git a/fs/xfs/libxfs/xfs_inode_fork.h b/fs/xfs/libxfs/xfs_inode_fork.h
> index d0e49b015b62..850d53162545 100644
> --- a/fs/xfs/libxfs/xfs_inode_fork.h
> +++ b/fs/xfs/libxfs/xfs_inode_fork.h
> @@ -78,7 +78,14 @@ struct xfs_ifork {
> * split into two extents causing extent count to increase by 1.
> */
> #define XFS_IEXT_INSERT_HOLE_CNT (1)
> -
> +/*
> + * Moving an extent to data fork can cause a sub-interval of an existing extent
> + * to be unmapped. This will increase extent count by 1. Mapping in the new
> + * extent can increase the extent count by 1 again i.e.
> + * | Old extent | New extent | Old extent |
> + * Hence number of extents increases by 2.
> + */
> +#define XFS_IEXT_REFLINK_END_COW_CNT (2)
>
> /*
> * Fork handling.
> diff --git a/fs/xfs/xfs_reflink.c b/fs/xfs/xfs_reflink.c
> index aac83f9d6107..c1d2a741e1af 100644
> --- a/fs/xfs/xfs_reflink.c
> +++ b/fs/xfs/xfs_reflink.c
> @@ -628,6 +628,11 @@ xfs_reflink_end_cow_extent(
> xfs_ilock(ip, XFS_ILOCK_EXCL);
> xfs_trans_ijoin(tp, ip, 0);
>
> + error = xfs_iext_count_may_overflow(ip, XFS_DATA_FORK,
> + XFS_IEXT_REFLINK_END_COW_CNT);
> + if (error)
> + goto out_cancel;
What happens if we fail here? I think for buffered writes this means
that writeback fails and we store an EIO in the address space for
eventual return via fsync()? And for a direct write this means that
EIO gets sent back to the caller, right?
Assuming I understood that correctly, I think this is a reasonable
enough place to check for overflows, and hence
Reviewed-by: Darrick J. Wong <darrick.wong@oracle.com>
It would be nicer to check this kind of thing at write() time to put all
the EFBIG errors up front, but I don't think you can do that without
tracking extent count "reservations" incore.
--D
> +
> /*
> * In case of racing, overlapping AIO writes no COW extents might be
> * left by the time I/O completes for the loser of the race. In that
> --
> 2.28.0
>
next prev parent reply other threads:[~2020-08-31 16:29 UTC|newest]
Thread overview: 29+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-08-20 5:43 [PATCH V3 00/10] Bail out if transaction can cause extent count to overflow Chandan Babu R
2020-08-20 5:43 ` [PATCH V3 01/10] xfs: Add helper for checking per-inode extent count overflow Chandan Babu R
2020-08-31 16:08 ` Darrick J. Wong
2020-08-31 16:44 ` Darrick J. Wong
2020-09-01 9:44 ` Chandan Babu R
2020-08-20 5:43 ` [PATCH V3 02/10] xfs: Check for extent overflow when trivally adding a new extent Chandan Babu R
2020-08-31 16:12 ` Darrick J. Wong
2020-08-20 5:43 ` [PATCH V3 03/10] xfs: Check for extent overflow when deleting an extent Chandan Babu R
2020-08-31 16:34 ` Darrick J. Wong
2020-09-01 9:44 ` Chandan Babu R
2020-08-20 5:43 ` [PATCH V3 04/10] xfs: Check for extent overflow when adding/removing xattrs Chandan Babu R
2020-08-31 16:37 ` Darrick J. Wong
2020-09-01 9:44 ` Chandan Babu R
2020-08-20 5:43 ` [PATCH V3 05/10] xfs: Check for extent overflow when adding/removing dir entries Chandan Babu R
2020-08-31 16:41 ` Darrick J. Wong
2020-08-20 5:43 ` [PATCH V3 06/10] xfs: Check for extent overflow when writing to unwritten extent Chandan Babu R
2020-08-31 16:45 ` Darrick J. Wong
2020-08-20 5:43 ` [PATCH V3 07/10] xfs: Check for extent overflow when inserting a hole Chandan Babu R
2020-08-31 16:46 ` Darrick J. Wong
2020-09-01 9:44 ` Chandan Babu R
2020-08-20 5:43 ` [PATCH V3 08/10] xfs: Check for extent overflow when moving extent from cow to data fork Chandan Babu R
2020-08-31 16:29 ` Darrick J. Wong [this message]
2020-09-01 9:45 ` Chandan Babu R
2020-08-20 5:43 ` [PATCH V3 09/10] xfs: Check for extent overflow when remapping an extent Chandan Babu R
2020-08-31 16:23 ` Darrick J. Wong
2020-09-01 9:45 ` Chandan Babu R
2020-08-20 5:43 ` [PATCH V3 10/10] xfs: Check for extent overflow when swapping extents Chandan Babu R
2020-08-31 16:20 ` Darrick J. Wong
2020-09-01 9:45 ` Chandan Babu R
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=20200831162908.GK6096@magnolia \
--to=darrick.wong@oracle.com \
--cc=chandanrlinux@gmail.com \
--cc=david@fromorbit.com \
--cc=hch@infradead.org \
--cc=linux-xfs@vger.kernel.org \
/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