On Tue, Apr 17, 2018 at 07:57:55PM -0700, Darrick J. Wong wrote:
> From: Darrick J. Wong <darrick.wong@xxxxxxxxxx>
>
> Since deduplication potentially has to read in all the pages in both
> files in order to compare the contents, cap the deduplication request
> length at MAX_RW_COUNT/2 (roughly 1GB) so that we have /some/ upper bound
> on the request length and can't just lock up the kernel forever. Found
> by running generic/304 after commit 1ddae54555b62a ("common/rc: add
> missing 'local' keywords").
>
> Signed-off-by: Darrick J. Wong <darrick.wong@xxxxxxxxxx>
Looks good,
Reviewed-by: Carlos Maiolino <cmaiolino@xxxxxxxxxx>
> ---
> v2: halve the amount so that we do MAX_RW_COUNT IO max
> ---
> fs/xfs/xfs_file.c | 10 ++++++++++
> 1 file changed, 10 insertions(+)
>
> diff --git a/fs/xfs/xfs_file.c b/fs/xfs/xfs_file.c
> index 299aee4..9cafad4 100644
> --- a/fs/xfs/xfs_file.c
> +++ b/fs/xfs/xfs_file.c
> @@ -876,8 +876,18 @@ xfs_file_dedupe_range(
> struct file *dst_file,
> u64 dst_loff)
> {
> + struct inode *srci = file_inode(src_file);
> + u64 max_dedupe;
> int error;
>
> + /*
> + * Since we have to read all these pages in to compare them, cut
> + * it off at MAX_RW_COUNT/2 rounded down to the nearest block.
> + * That means we won't do more than MAX_RW_COUNT IO per request.
> + */
> + max_dedupe = (MAX_RW_COUNT >> 1) & ~(i_blocksize(srci) - 1);
> + if (len > max_dedupe)
> + len = max_dedupe;
> error = xfs_reflink_remap_range(src_file, loff, dst_file, dst_loff,
> len, true);
> if (error)
> --
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--
Carlos
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