linux-kernel - Re: [PATCH 1/3] mm: add filemap_fdatawait_range_keep

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Date:   Thu, 20 Jun 2019 11:25:52 +0200
From:   Jan Kara <jack@...e.cz>
To:     Ross Zwisler <zwisler@...omium.org>
Cc:     linux-kernel@...r.kernel.org, Ross Zwisler <zwisler@...gle.com>,
        Theodore Ts'o <tytso@....edu>,
        Alexander Viro <viro@...iv.linux.org.uk>,
        Andreas Dilger <adilger.kernel@...ger.ca>,
        Jan Kara <jack@...e.com>, linux-ext4@...r.kernel.org,
        linux-fsdevel@...r.kernel.org, linux-mm@...ck.org,
        Fletcher Woodruff <fletcherw@...gle.com>,
        Justin TerAvest <teravest@...gle.com>
Subject: Re: [PATCH 1/3] mm: add filemap_fdatawait_range_keep_errors()

On Wed 19-06-19 11:21:54, Ross Zwisler wrote:
> In the spirit of filemap_fdatawait_range() and
> filemap_fdatawait_keep_errors(), introduce
> filemap_fdatawait_range_keep_errors() which both takes a range upon
> which to wait and does not clear errors from the address space.
> 
> Signed-off-by: Ross Zwisler <zwisler@...gle.com>

The patch looks good to me. You can add:

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

								Honza

> ---
>  include/linux/fs.h |  2 ++
>  mm/filemap.c       | 22 ++++++++++++++++++++++
>  2 files changed, 24 insertions(+)
> 
> diff --git a/include/linux/fs.h b/include/linux/fs.h
> index f7fdfe93e25d3..79fec8a8413f4 100644
> --- a/include/linux/fs.h
> +++ b/include/linux/fs.h
> @@ -2712,6 +2712,8 @@ extern int filemap_flush(struct address_space *);
>  extern int filemap_fdatawait_keep_errors(struct address_space *mapping);
>  extern int filemap_fdatawait_range(struct address_space *, loff_t lstart,
>  				   loff_t lend);
> +extern int filemap_fdatawait_range_keep_errors(struct address_space *mapping,
> +		loff_t start_byte, loff_t end_byte);
>  
>  static inline int filemap_fdatawait(struct address_space *mapping)
>  {
> diff --git a/mm/filemap.c b/mm/filemap.c
> index df2006ba0cfa5..e87252ca0835a 100644
> --- a/mm/filemap.c
> +++ b/mm/filemap.c
> @@ -553,6 +553,28 @@ int filemap_fdatawait_range(struct address_space *mapping, loff_t start_byte,
>  }
>  EXPORT_SYMBOL(filemap_fdatawait_range);
>  
> +/**
> + * filemap_fdatawait_range_keep_errors - wait for writeback to complete
> + * @mapping:		address space structure to wait for
> + * @start_byte:		offset in bytes where the range starts
> + * @end_byte:		offset in bytes where the range ends (inclusive)
> + *
> + * Walk the list of under-writeback pages of the given address space in the
> + * given range and wait for all of them.  Unlike filemap_fdatawait_range(),
> + * this function does not clear error status of the address space.
> + *
> + * Use this function if callers don't handle errors themselves.  Expected
> + * call sites are system-wide / filesystem-wide data flushers: e.g. sync(2),
> + * fsfreeze(8)
> + */
> +int filemap_fdatawait_range_keep_errors(struct address_space *mapping,
> +		loff_t start_byte, loff_t end_byte)
> +{
> +	__filemap_fdatawait_range(mapping, start_byte, end_byte);
> +	return filemap_check_and_keep_errors(mapping);
> +}
> +EXPORT_SYMBOL(filemap_fdatawait_range_keep_errors);
> +
>  /**
>   * file_fdatawait_range - wait for writeback to complete
>   * @file:		file pointing to address space structure to wait for
> -- 
> 2.22.0.410.gd8fdbe21b5-goog
> 
> 
-- 
Jan Kara <jack@...e.com>
SUSE Labs, CR