From 021ba8e98fe5c6691b3cc3669faafa02403aa211 Mon Sep 17 00:00:00 2001
From: "Darrick J. Wong" <darrick.wong@oracle.com>
Date: Mon, 16 Apr 2018 23:07:36 -0700
Subject: 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>
---
fs/xfs/xfs_file.c | 10 ++++++++++
1 file changed, 10 insertions(+)
(limited to 'fs')
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)
--
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