GFS2: Fix direct IO write rounding error

The fsx test in xfstests was failing because it was using direct IO
writes which were using a bad calculation. It was using
loff_t lstart = offset & (PAGE_CACHE_SIZE - 1); when it should be
loff_t lstart = offset & ~(PAGE_CACHE_SIZE - 1);
Thus, the write at offset 0x67e00 was calculating lstart to be
0xe00, the address of our corruption. Instead, it should have been
0x67000. This patch fixes the calculation.

Signed-off-by: Bob Peterson <rpeterso@redhat.com>
Acked-by: Steven Whitehouse <swhiteho@redhat.com>

diff --git a/fs/gfs2/aops.c b/fs/gfs2/aops.c
index 93f07465e5a682618844fa53bba03c859526141e..aa016e4b8bec976d57b8a36cdbb3c12c7e8e39ff 100644 (file)
--- a/fs/gfs2/aops.c
+++ b/fs/gfs2/aops.c
@@ -1082,7 +1082,7 @@ static ssize_t gfs2_direct_IO(struct kiocb *iocb, struct iov_iter *iter,
         * the first place, mapping->nr_pages will always be zero.
         */
        if (mapping->nrpages) {
-               loff_t lstart = offset & (PAGE_CACHE_SIZE - 1);
+               loff_t lstart = offset & ~(PAGE_CACHE_SIZE - 1);
                loff_t len = iov_iter_count(iter);
                loff_t end = PAGE_ALIGN(offset + len) - 1;