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Date: Wed, 22 Jul 2020 16:13:52 -0700
From: "Darrick J. Wong" <darrick.wong@...cle.com>
To: "Theodore Ts'o" <tytso@....edu>
Cc: Dave Chinner <david@...morbit.com>,
Goldwyn Rodrigues <rgoldwyn@...e.de>,
Damien Le Moal <damien.lemoal@....com>,
Naohiro Aota <naohiro.aota@....com>,
Johannes Thumshirn <jth@...nel.org>,
Matthew Wilcox <willy@...radead.org>,
linux-btrfs@...r.kernel.org, linux-fsdevel@...r.kernel.org,
cluster-devel@...hat.com, linux-ext4@...r.kernel.org,
linux-xfs@...r.kernel.org, Dave Chinner <dchinner@...hat.com>,
Goldwyn Rodrigues <rgoldwyn@...e.com>,
Christoph Hellwig <hch@...radead.org>
Subject: Re: [PATCH 3/3] iomap: fall back to buffered writes for invalidation
failures
Hey Ted,
Could you please review the fs/ext4/ part of this patch (it's the
follow-on to the directio discussion I had with you last week) so that I
can get this moving for 5.9? Thx,
--D
On Tue, Jul 21, 2020 at 08:31:57PM +0200, Christoph Hellwig wrote:
> Failing to invalid the page cache means data in incoherent, which is
> a very bad state for the system. Always fall back to buffered I/O
> through the page cache if we can't invalidate mappings.
>
> Signed-off-by: Christoph Hellwig <hch@....de>
> Acked-by: Dave Chinner <dchinner@...hat.com>
> Reviewed-by: Goldwyn Rodrigues <rgoldwyn@...e.com>
> ---
> fs/ext4/file.c | 2 ++
> fs/gfs2/file.c | 3 ++-
> fs/iomap/direct-io.c | 16 +++++++++++-----
> fs/iomap/trace.h | 1 +
> fs/xfs/xfs_file.c | 4 ++--
> fs/zonefs/super.c | 7 +++++--
> 6 files changed, 23 insertions(+), 10 deletions(-)
>
> diff --git a/fs/ext4/file.c b/fs/ext4/file.c
> index 2a01e31a032c4c..129cc1dd6b7952 100644
> --- a/fs/ext4/file.c
> +++ b/fs/ext4/file.c
> @@ -544,6 +544,8 @@ static ssize_t ext4_dio_write_iter(struct kiocb *iocb, struct iov_iter *from)
> iomap_ops = &ext4_iomap_overwrite_ops;
> ret = iomap_dio_rw(iocb, from, iomap_ops, &ext4_dio_write_ops,
> is_sync_kiocb(iocb) || unaligned_io || extend);
> + if (ret == -ENOTBLK)
> + ret = 0;
>
> if (extend)
> ret = ext4_handle_inode_extension(inode, offset, ret, count);
> diff --git a/fs/gfs2/file.c b/fs/gfs2/file.c
> index bebde537ac8cf2..b085a3bea4f0fd 100644
> --- a/fs/gfs2/file.c
> +++ b/fs/gfs2/file.c
> @@ -835,7 +835,8 @@ static ssize_t gfs2_file_direct_write(struct kiocb *iocb, struct iov_iter *from)
>
> ret = iomap_dio_rw(iocb, from, &gfs2_iomap_ops, NULL,
> is_sync_kiocb(iocb));
> -
> + if (ret == -ENOTBLK)
> + ret = 0;
> out:
> gfs2_glock_dq(&gh);
> out_uninit:
> diff --git a/fs/iomap/direct-io.c b/fs/iomap/direct-io.c
> index 190967e87b69e4..c1aafb2ab99072 100644
> --- a/fs/iomap/direct-io.c
> +++ b/fs/iomap/direct-io.c
> @@ -10,6 +10,7 @@
> #include <linux/backing-dev.h>
> #include <linux/uio.h>
> #include <linux/task_io_accounting_ops.h>
> +#include "trace.h"
>
> #include "../internal.h"
>
> @@ -401,6 +402,9 @@ iomap_dio_actor(struct inode *inode, loff_t pos, loff_t length,
> * can be mapped into multiple disjoint IOs and only a subset of the IOs issued
> * may be pure data writes. In that case, we still need to do a full data sync
> * completion.
> + *
> + * Returns -ENOTBLK In case of a page invalidation invalidation failure for
> + * writes. The callers needs to fall back to buffered I/O in this case.
> */
> ssize_t
> iomap_dio_rw(struct kiocb *iocb, struct iov_iter *iter,
> @@ -478,13 +482,15 @@ iomap_dio_rw(struct kiocb *iocb, struct iov_iter *iter,
> if (iov_iter_rw(iter) == WRITE) {
> /*
> * Try to invalidate cache pages for the range we are writing.
> - * If this invalidation fails, tough, the write will still work,
> - * but racing two incompatible write paths is a pretty crazy
> - * thing to do, so we don't support it 100%.
> + * If this invalidation fails, let the caller fall back to
> + * buffered I/O.
> */
> if (invalidate_inode_pages2_range(mapping, pos >> PAGE_SHIFT,
> - end >> PAGE_SHIFT))
> - dio_warn_stale_pagecache(iocb->ki_filp);
> + end >> PAGE_SHIFT)) {
> + trace_iomap_dio_invalidate_fail(inode, pos, count);
> + ret = -ENOTBLK;
> + goto out_free_dio;
> + }
>
> if (!wait_for_completion && !inode->i_sb->s_dio_done_wq) {
> ret = sb_init_dio_done_wq(inode->i_sb);
> diff --git a/fs/iomap/trace.h b/fs/iomap/trace.h
> index 5693a39d52fb63..fdc7ae388476f5 100644
> --- a/fs/iomap/trace.h
> +++ b/fs/iomap/trace.h
> @@ -74,6 +74,7 @@ DEFINE_EVENT(iomap_range_class, name, \
> DEFINE_RANGE_EVENT(iomap_writepage);
> DEFINE_RANGE_EVENT(iomap_releasepage);
> DEFINE_RANGE_EVENT(iomap_invalidatepage);
> +DEFINE_RANGE_EVENT(iomap_dio_invalidate_fail);
>
> #define IOMAP_TYPE_STRINGS \
> { IOMAP_HOLE, "HOLE" }, \
> diff --git a/fs/xfs/xfs_file.c b/fs/xfs/xfs_file.c
> index a6ef90457abf97..1b4517fc55f1b9 100644
> --- a/fs/xfs/xfs_file.c
> +++ b/fs/xfs/xfs_file.c
> @@ -553,8 +553,8 @@ xfs_file_dio_aio_write(
> xfs_iunlock(ip, iolock);
>
> /*
> - * No fallback to buffered IO on errors for XFS, direct IO will either
> - * complete fully or fail.
> + * No fallback to buffered IO after short writes for XFS, direct I/O
> + * will either complete fully or return an error.
> */
> ASSERT(ret < 0 || ret == count);
> return ret;
> diff --git a/fs/zonefs/super.c b/fs/zonefs/super.c
> index 07bc42d62673ce..d0a04528a7e18e 100644
> --- a/fs/zonefs/super.c
> +++ b/fs/zonefs/super.c
> @@ -786,8 +786,11 @@ static ssize_t zonefs_file_write_iter(struct kiocb *iocb, struct iov_iter *from)
> if (iocb->ki_pos >= ZONEFS_I(inode)->i_max_size)
> return -EFBIG;
>
> - if (iocb->ki_flags & IOCB_DIRECT)
> - return zonefs_file_dio_write(iocb, from);
> + if (iocb->ki_flags & IOCB_DIRECT) {
> + ssize_t ret = zonefs_file_dio_write(iocb, from);
> + if (ret != -ENOTBLK)
> + return ret;
> + }
>
> return zonefs_file_buffered_write(iocb, from);
> }
> --
> 2.27.0
>
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