linux-kernel - Re: [PATCH v2 2/3] fs: keep dio_warn_stale_pagecache() when CONFIG

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Message-ID: <20191121162216.GB18158@quack2.suse.cz>
Date:   Thu, 21 Nov 2019 17:22:16 +0100
From:   Jan Kara <jack@...e.cz>
To:     Konstantin Khlebnikov <khlebnikov@...dex-team.ru>
Cc:     linux-mm@...ck.org, Andrew Morton <akpm@...ux-foundation.org>,
        linux-kernel@...r.kernel.org, linux-fsdevel@...r.kernel.org,
        Jens Axboe <axboe@...nel.dk>, Jan Kara <jack@...e.cz>,
        Alexander Viro <viro@...iv.linux.org.uk>
Subject: Re: [PATCH v2 2/3] fs: keep dio_warn_stale_pagecache() when
 CONFIG_BLOCK=n

On Sat 02-11-19 16:13:00, Konstantin Khlebnikov wrote:
> This helper prints warning if direct I/O write failed to invalidate cache,
> and set EIO at inode to warn usersapce about possible data corruption.
> See also commit 5a9d929d6e13 ("iomap: report collisions between directio and
> buffered writes to userspace").
> 
> Direct I/O is supported by non-disk filesystems, for example NFS.
> Thus generic code needs this even in kernel without CONFIG_BLOCK.
> 
> Signed-off-by: Konstantin Khlebnikov <khlebnikov@...dex-team.ru>

Looks good to me. You can add:

Reviewed-by: Jan Kara <jack@...e.cz>

								Honza

> ---
>  fs/direct-io.c     |   21 ---------------------
>  include/linux/fs.h |    6 +++++-
>  mm/filemap.c       |   21 +++++++++++++++++++++
>  3 files changed, 26 insertions(+), 22 deletions(-)
> 
> diff --git a/fs/direct-io.c b/fs/direct-io.c
> index 9329ced91f1d..0ec4f270139f 100644
> --- a/fs/direct-io.c
> +++ b/fs/direct-io.c
> @@ -220,27 +220,6 @@ static inline struct page *dio_get_page(struct dio *dio,
>  	return dio->pages[sdio->head];
>  }
>  
> -/*
> - * Warn about a page cache invalidation failure during a direct io write.
> - */
> -void dio_warn_stale_pagecache(struct file *filp)
> -{
> -	static DEFINE_RATELIMIT_STATE(_rs, 86400 * HZ, DEFAULT_RATELIMIT_BURST);
> -	char pathname[128];
> -	struct inode *inode = file_inode(filp);
> -	char *path;
> -
> -	errseq_set(&inode->i_mapping->wb_err, -EIO);
> -	if (__ratelimit(&_rs)) {
> -		path = file_path(filp, pathname, sizeof(pathname));
> -		if (IS_ERR(path))
> -			path = "(unknown)";
> -		pr_crit("Page cache invalidation failure on direct I/O.  Possible data corruption due to collision with buffered I/O!\n");
> -		pr_crit("File: %s PID: %d Comm: %.20s\n", path, current->pid,
> -			current->comm);
> -	}
> -}
> -
>  /*
>   * dio_complete() - called when all DIO BIO I/O has been completed
>   *
> diff --git a/include/linux/fs.h b/include/linux/fs.h
> index e0d909d35763..b4e4560d1c38 100644
> --- a/include/linux/fs.h
> +++ b/include/linux/fs.h
> @@ -3153,7 +3153,6 @@ enum {
>  };
>  
>  void dio_end_io(struct bio *bio);
> -void dio_warn_stale_pagecache(struct file *filp);
>  
>  ssize_t __blockdev_direct_IO(struct kiocb *iocb, struct inode *inode,
>  			     struct block_device *bdev, struct iov_iter *iter,
> @@ -3198,6 +3197,11 @@ static inline void inode_dio_end(struct inode *inode)
>  		wake_up_bit(&inode->i_state, __I_DIO_WAKEUP);
>  }
>  
> +/*
> + * Warn about a page cache invalidation failure diring a direct I/O write.
> + */
> +void dio_warn_stale_pagecache(struct file *filp);
> +
>  extern void inode_set_flags(struct inode *inode, unsigned int flags,
>  			    unsigned int mask);
>  
> diff --git a/mm/filemap.c b/mm/filemap.c
> index 288e38199068..189b8f318da2 100644
> --- a/mm/filemap.c
> +++ b/mm/filemap.c
> @@ -3161,6 +3161,27 @@ int pagecache_write_end(struct file *file, struct address_space *mapping,
>  }
>  EXPORT_SYMBOL(pagecache_write_end);
>  
> +/*
> + * Warn about a page cache invalidation failure during a direct I/O write.
> + */
> +void dio_warn_stale_pagecache(struct file *filp)
> +{
> +	static DEFINE_RATELIMIT_STATE(_rs, 86400 * HZ, DEFAULT_RATELIMIT_BURST);
> +	char pathname[128];
> +	struct inode *inode = file_inode(filp);
> +	char *path;
> +
> +	errseq_set(&inode->i_mapping->wb_err, -EIO);
> +	if (__ratelimit(&_rs)) {
> +		path = file_path(filp, pathname, sizeof(pathname));
> +		if (IS_ERR(path))
> +			path = "(unknown)";
> +		pr_crit("Page cache invalidation failure on direct I/O.  Possible data corruption due to collision with buffered I/O!\n");
> +		pr_crit("File: %s PID: %d Comm: %.20s\n", path, current->pid,
> +			current->comm);
> +	}
> +}
> +
>  ssize_t
>  generic_file_direct_write(struct kiocb *iocb, struct iov_iter *from)
>  {
> 
-- 
Jan Kara <jack@...e.com>
SUSE Labs, CR