1 files changed, 10 insertions, 0 deletions

diff --git a/fs/xfs/xfs_file.c b/fs/xfs/xfs_file.c
index eed073cc4778..e70fb8ccecea 100644
--- a/fs/xfs/xfs_file.c
+++ b/fs/xfs/xfs_file.c
@@ -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)