Commit 2e171ffc authored May 04, 2018 by Linus Torvalds

xfs-linux

Pull xfs fixes from Darrick Wong:
 "I've got one more bug fix for xfs for 4.17-rc4, which caps the amount
  of data we try to handle in one dedupe request so that userspace can't
  livelock the kernel.

  This series has been run through a full xfstests run during the week
  and through a quick xfstests run against this morning's master, with
  no ajor failures reported.

  Summary:

  - Cap the maximum length of a deduplication request at MAX_RW_COUNT/2
    to avoid kernel livelock due to excessively large IO requests"

* tag 'xfs-4.17-fixes-2' of git://git.kernel.org/pub/scm/fs/xfs/xfs-linux:
  xfs: cap the length of deduplication requests

parents 4148d388 021ba8e9

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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