Commit 021ba8e9 authored Apr 16, 2018 by Darrick J. Wong

xfs: cap the length of deduplication requests



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 1ddae54555b62 ("common/rc: add
missing 'local' keywords").

Reported-by:  <matorola@gmail.com>
Signed-off-by: Darrick J. Wong <darrick.wong@oracle.com>
Reviewed-by: Carlos Maiolino <cmaiolino@redhat.com>

parent 7b38460d

fs/xfs/xfs_file.c

+10 −0

Original line number	Diff line number	Diff line
		@@ -880,8 +880,18 @@ 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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