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From: Brian Foster <bfoster@redhat.com>
To: "Darrick J. Wong" <darrick.wong@oracle.com>
Cc: xfs <linux-xfs@vger.kernel.org>,
	Matthew Wilcox <willy@infradead.org>,
	linux-fsdevel@vger.kernel.org, fstests@vger.kernel.org,
	Jeff Layton <jlayton@kernel.org>
Subject: Re: [PATCH v3] fs: clear writeback errors in inode_init_always
Date: Tue, 22 May 2018 14:40:09 -0400	[thread overview]
Message-ID: <20180522184009.GC25403@bfoster.bfoster> (raw)
In-Reply-To: <20180522164359.GB12940@magnolia>

On Tue, May 22, 2018 at 09:43:59AM -0700, Darrick J. Wong wrote:
> From: Darrick J. Wong <darrick.wong@oracle.com>
> 
> In inode_init_always(), we clear the inode mapping flags, which clears
> any retained error (AS_EIO, AS_ENOSPC) bits.  Unfortunately, we do not
> also clear wb_err, which means that old mapping errors can leak through
> to new inodes.
> 
> This is crucial for the XFS inode allocation path because we recycle old
> in-core inodes and we do not want error state from an old file to leak
> into the new file.  This bug was discovered by running generic/036 and
> generic/047 in a loop and noticing that the EIOs generated by the
> collision of direct and buffered writes in generic/036 would survive the
> remount between 036 and 047, and get reported to the fsyncs (on
> different files!) in generic/047.
> 
> Since we're changing the semantics of inode_init_always, we must also
> change xfs_reinit_inode to retain the writeback error state when we go
> to recover an inode that has been torn down in the vfs but not yet
> disposed of by XFS.
> 
> Signed-off-by: Darrick J. Wong <darrick.wong@oracle.com>
> Reviewed-by: Jeff Layton <jlayton@kernel.org>
> ---
> v3: clear error state when allocating new inode
> v2: retain AS_EIO/AS_ENOSPC across xfs inode reinit
> ---
>  fs/inode.c          |    1 +
>  fs/xfs/xfs_icache.c |    9 +++++++++
>  fs/xfs/xfs_inode.c  |    5 +++++
>  3 files changed, 15 insertions(+)
> 
> diff --git a/fs/inode.c b/fs/inode.c
> index 13ceb98c3bd3..3b55391072f3 100644
> --- a/fs/inode.c
> +++ b/fs/inode.c
> @@ -178,6 +178,7 @@ int inode_init_always(struct super_block *sb, struct inode *inode)
>  	mapping->a_ops = &empty_aops;
>  	mapping->host = inode;
>  	mapping->flags = 0;
> +	mapping->wb_err = 0;
>  	atomic_set(&mapping->i_mmap_writable, 0);
>  	mapping_set_gfp_mask(mapping, GFP_HIGHUSER_MOVABLE);
>  	mapping->private_data = NULL;
> diff --git a/fs/xfs/xfs_icache.c b/fs/xfs/xfs_icache.c
> index 164350d91efc..d01f9544ff01 100644
> --- a/fs/xfs/xfs_icache.c
> +++ b/fs/xfs/xfs_icache.c
> @@ -298,6 +298,10 @@ xfs_reinit_inode(
>  	uint64_t	version = inode_peek_iversion(inode);
>  	umode_t		mode = inode->i_mode;
>  	dev_t		dev = inode->i_rdev;
> +	errseq_t	old_err = inode->i_mapping->wb_err;
> +	bool		as_eio = test_bit(AS_EIO, &inode->i_mapping->flags);
> +	bool		as_enospc = test_bit(AS_ENOSPC,
> +					     &inode->i_mapping->flags);
>  
>  	error = inode_init_always(mp->m_super, inode);
>  
> @@ -306,6 +310,11 @@ xfs_reinit_inode(
>  	inode_set_iversion_queried(inode, version);
>  	inode->i_mode = mode;
>  	inode->i_rdev = dev;
> +	inode->i_mapping->wb_err = old_err;
> +	if (as_eio)
> +		set_bit(AS_EIO, &inode->i_mapping->flags);
> +	if (as_enospc)
> +		set_bit(AS_ENOSPC, &inode->i_mapping->flags);
>  	return error;
>  }
>  
> diff --git a/fs/xfs/xfs_inode.c b/fs/xfs/xfs_inode.c
> index 02eae5059231..6c47ea3e577b 100644
> --- a/fs/xfs/xfs_inode.c
> +++ b/fs/xfs/xfs_inode.c
> @@ -835,6 +835,11 @@ xfs_ialloc(
>  			inode->i_mode |= S_ISGID;
>  	}
>  
> +	/* Reset all vfs error state. */

I'd prefer a comment that reminds why we have to do this. E.g.,
something like:

	/*
	 * In-core inode reinit carries over vfs error state. Reset it
	 * so we don't leak error state from a previous generation of
	 * the inode.
	 */

... but feel free to reword that.

> +	inode->i_mapping->wb_err = 0;
> +	clear_bit(AS_EIO, &inode->i_mapping->flags);
> +	clear_bit(AS_ENOSPC, &inode->i_mapping->flags);
> +

I also wonder whether it might be cleaner to just reset this stuff in
xfs_ifree() where we kill the i_mode and bump the gen and whatnot, but
afaict this should work too. With the comment fix, at least:

Reviewed-by: Brian Foster <bfoster@redhat.com>

>  	/*
>  	 * If the group ID of the new file does not match the effective group
>  	 * ID or one of the supplementary group IDs, the S_ISGID bit is cleared
> --
> To unsubscribe from this list: send the line "unsubscribe linux-xfs" in
> the body of a message to majordomo@vger.kernel.org
> More majordomo info at  http://vger.kernel.org/majordomo-info.html

  reply	other threads:[~2018-05-22 18:40 UTC|newest]

Thread overview: 30+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2018-05-18 22:50 commit b4678df184b causing xfstests regressions Theodore Y. Ts'o
2018-05-19  2:17 ` Matthew Wilcox
2018-05-19 13:09 ` Jeff Layton
2018-05-19 15:25   ` Darrick J. Wong
2018-05-19 15:27   ` [PATCH] fs: clear writeback errors in inode_init_always Darrick J. Wong
2018-05-19 15:36     ` Matthew Wilcox
2018-05-21 17:54       ` Darrick J. Wong
2018-05-22 10:30         ` Jeff Layton
2018-05-22 22:09           ` Dave Chinner
2018-05-23 10:56             ` Jeff Layton
2018-05-24  3:59               ` Dave Chinner
2018-05-19 23:19     ` Theodore Y. Ts'o
2018-05-20 11:45       ` Jeff Layton
2018-05-20 12:58         ` Matthew Wilcox
2018-05-20 13:18           ` Jeff Layton
2018-05-20 16:29           ` Theodore Y. Ts'o
2018-05-20 19:20             ` Matthew Wilcox
2018-05-20 19:41               ` Theodore Y. Ts'o
2018-05-21 11:20                 ` Jeff Layton
2018-05-21 14:43                   ` Theodore Y. Ts'o
2018-05-20 17:57         ` Theodore Y. Ts'o
2018-05-22  4:06     ` [PATCH v2] " Darrick J. Wong
2018-05-22 10:14       ` Jeff Layton
2018-05-22 12:14       ` Brian Foster
2018-05-22 14:37         ` Darrick J. Wong
2018-05-22 16:43     ` [PATCH v3] " Darrick J. Wong
2018-05-22 18:40       ` Brian Foster [this message]
2018-05-22 18:47         ` Darrick J. Wong
2018-05-22 22:05       ` Dave Chinner
2018-05-23  3:00         ` Darrick J. Wong

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