summaryrefslogtreecommitdiffstats
diff options
context:
space:
mode:
authorArtem Bityutskiy <Artem.Bityutskiy@nokia.com>2011-05-15 14:51:54 +0300
committerArtem Bityutskiy <Artem.Bityutskiy@nokia.com>2011-05-16 10:31:41 +0300
commitcb14a18465686ea6add51b1008865b8174c28bd7 (patch)
tree9e1b7aa466e83c77628fa74af00049893db84c40
parentc49139d8096dc1c392455dbc3f158b46038fc9d4 (diff)
downloadlinux-cb14a18465686ea6add51b1008865b8174c28bd7.tar.bz2
UBIFS: synchronize write-buffer before switching to the next bud
Currently when UBIFS fills up the current bud (which is the last in the journal head) and switches to the next bud, it first writes the log reference node for the next bud and only after this synchronizes the write-buffer of the previous bud. This is not a big deal, but an unclean power cut may lead to a situation when we have corruption in a next-to-last bud, although it is much more logical that we have to have corruption only in the last bud. This patch also removes write-buffer synchronization from 'ubifs_wbuf_seek_nolock()' because this is not needed anymore (we synchronize the write-buffer explicitly everywhere now) and also because this is just prone to various errors. Signed-off-by: Artem Bityutskiy <Artem.Bityutskiy@nokia.com>
-rw-r--r--fs/ubifs/gc.c4
-rw-r--r--fs/ubifs/io.c12
-rw-r--r--fs/ubifs/journal.c25
3 files changed, 22 insertions, 19 deletions
diff --git a/fs/ubifs/gc.c b/fs/ubifs/gc.c
index d70937b3f8e9..ded29f6224c2 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 67bbde3550cf..166951e0dcd3 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 ce55a4807cdc..34b1679e6e3a 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;