msync: fix incorrect fstart calculation

Fix a regression caused by 7fc34a6 ("mm/msync.c: sync only the requested range in msync()"). xfstests generic/075 fail occured on ext4 data=journal mode because the intended range was not syncing due to wrong fstart calculation. Signed-off-by: Namjae Jeon <[email protected]> Signed-off-by: Ashish Sangwan <[email protected]> Reported-by: Eric Whitney <[email protected]> Tested-by: Eric Whitney <[email protected]> Acked-by: Matthew Wilcox <[email protected]> Reviewed-by: Lukas Czerner <[email protected]> Tested-by: Lukas Czerner <[email protected]> Reviewed-by: Theodore Ts'o <[email protected]> Signed-off-by: Andrew Morton <[email protected]> Signed-off-by: Linus Torvalds <[email protected]>
grate-driver · Jul 3, 2014 · 496a8e6 · 496a8e6
1 parent 2e32bae
commit 496a8e6
Showing 1 changed file with 2 additions and 1 deletion.
diff --git a/mm/msync.c b/mm/msync.c
@@ -78,7 +78,8 @@ SYSCALL_DEFINE3(msync, unsigned long, start, size_t, len, int, flags)
 			goto out_unlock;
 		}
 		file = vma->vm_file;
-		fstart = start + ((loff_t)vma->vm_pgoff << PAGE_SHIFT);
+		fstart = (start - vma->vm_start) +
+			 ((loff_t)vma->vm_pgoff << PAGE_SHIFT);
 		fend = fstart + (min(end, vma->vm_end) - start) - 1;
 		start = vma->vm_end;
 		if ((flags & MS_SYNC) && file &&