3 files changed, 22 insertions, 19 deletions

diff --git a/fs/ubifs/gc.c b/fs/ubifs/gc.c
index d70937b..ded29f6 100644
--- a/fs/ubifs/gc.c
+++ b/fs/ubifs/gc.c
@@ -100,6 +100,10 @@ static int switch_gc_head(struct ubifs_info *c)
 	if (err)
 		return err;
 
+	err = ubifs_wbuf_sync_nolock(wbuf);
+	if (err)
+		return err;
+
 	err = ubifs_add_bud_to_log(c, GCHD, gc_lnum, 0);
 	if (err)
 		return err;
diff --git a/fs/ubifs/io.c b/fs/ubifs/io.c
index 67bbde3..166951e 100644
--- a/fs/ubifs/io.c
+++ b/fs/ubifs/io.c
@@ -452,8 +452,8 @@ int ubifs_wbuf_sync_nolock(struct ubifs_wbuf *wbuf)
  * @dtype: data type
  *
  * This function targets the write-buffer to logical eraseblock @lnum:@offs.
- * The write-buffer is synchronized if it is not empty. Returns zero in case of
- * success and a negative error code in case of failure.
+ * The write-buffer has to be empty. Returns zero in case of success and a
+ * negative error code in case of failure.
  */
 int ubifs_wbuf_seek_nolock(struct ubifs_wbuf *wbuf, int lnum, int offs,
 			   int dtype)
@@ -465,13 +465,7 @@ int ubifs_wbuf_seek_nolock(struct ubifs_wbuf *wbuf, int lnum, int offs,
 	ubifs_assert(offs >= 0 && offs <= c->leb_size);
 	ubifs_assert(offs % c->min_io_size == 0 && !(offs & 7));
 	ubifs_assert(lnum != wbuf->lnum);
-
-	if (wbuf->used > 0) {
-		int err = ubifs_wbuf_sync_nolock(wbuf);
-
-		if (err)
-			return err;
-	}
+	ubifs_assert(wbuf->used == 0);
 
 	spin_lock(&wbuf->lock);
 	wbuf->lnum = lnum;
diff --git a/fs/ubifs/journal.c b/fs/ubifs/journal.c
index ce55a48..34b1679 100644
--- a/fs/ubifs/journal.c
+++ b/fs/ubifs/journal.c
@@ -141,14 +141,8 @@ again:
 	 * LEB with some empty space.
 	 */
 	lnum = ubifs_find_free_space(c, len, &offs, squeeze);
-	if (lnum >= 0) {
-		/* Found an LEB, add it to the journal head */
-		err = ubifs_add_bud_to_log(c, jhead, lnum, offs);
-		if (err)
-			goto out_return;
-		/* A new bud was successfully allocated and added to the log */
+	if (lnum >= 0)
 		goto out;
-	}
 
 	err = lnum;
 	if (err != -ENOSPC)
@@ -203,12 +197,23 @@ again:
 		return 0;
 	}
 
-	err = ubifs_add_bud_to_log(c, jhead, lnum, 0);
-	if (err)
-		goto out_return;
 	offs = 0;
 
 out:
+	/*
+	 * Make sure we synchronize the write-buffer before we add the new bud
+	 * to the log. Otherwise we may have a power cut after the log
+	 * reference node for the last bud (@lnum) is written but before the
+	 * write-buffer data are written to the next-to-last bud
+	 * (@wbuf->lnum). And the effect would be that the recovery would see
+	 * that there is corruption in the next-to-last bud.
+	 */
+	err = ubifs_wbuf_sync_nolock(wbuf);
+	if (err)
+		goto out_return;
+	err = ubifs_add_bud_to_log(c, jhead, lnum, offs);
+	if (err)
+		goto out_return;
 	err = ubifs_wbuf_seek_nolock(wbuf, lnum, offs, wbuf->dtype);
 	if (err)
 		goto out_unlock;