1 files changed, 15 insertions, 4 deletions

diff --git a/fs/xfs/xfs_log_cil.c b/fs/xfs/xfs_log_cil.c
index cdebd832c3db..4ef6fdbced78 100644
--- a/fs/xfs/xfs_log_cil.c
+++ b/fs/xfs/xfs_log_cil.c
@@ -205,16 +205,25 @@ xlog_cil_insert_format_items(
                 /*
                  * We 64-bit align the length of each iovec so that the start
                  * of the next one is naturally aligned.  We'll need to
-                 * account for that slack space here.
+                 * account for that slack space here. Then round nbytes up
+                 * to 64-bit alignment so that the initial buffer alignment is
+                 * easy to calculate and verify.
                  */
                 nbytes += niovecs * sizeof(uint64_t);
+                nbytes = round_up(nbytes, sizeof(uint64_t));
 
                 /* grab the old item if it exists for reservation accounting */
                 old_lv = lip->li_lv;
 
-                /* calc buffer size */
-                buf_size = sizeof(struct xfs_log_vec) + nbytes +
-                                niovecs * sizeof(struct xfs_log_iovec);
+                /*
+                 * The data buffer needs to start 64-bit aligned, so round up
+                 * that space to ensure we can align it appropriately and not
+                 * overrun the buffer.
+                 */
+                buf_size = nbytes +
+                           round_up((sizeof(struct xfs_log_vec) +
+                                     niovecs * sizeof(struct xfs_log_iovec)),
+                                    sizeof(uint64_t));
 
                 /* compare to existing item size */
                 if (lip->li_lv && buf_size <= lip->li_lv->lv_size) {
@@ -251,6 +260,8 @@ xlog_cil_insert_format_items(
                 /* The allocated data region lies beyond the iovec region */
                 lv->lv_buf_len = 0;
                 lv->lv_buf = (char *)lv + buf_size - nbytes;
+                ASSERT(IS_ALIGNED((unsigned long)lv->lv_buf, sizeof(uint64_t)));
+
                 lip->li_ops->iop_format(lip, lv);
 insert:
                 ASSERT(lv->lv_buf_len <= nbytes);