JFS: Take logsync lock before testing mp->lsn
This fixes a race where lsn could be cleared before taking the lock
Signed-off-by: Dave Kleikamp <shaggy@austin.ibm.com>
diff --git a/fs/jfs/jfs_imap.c b/fs/jfs/jfs_imap.c
index 87dd86c..b62a048 100644
--- a/fs/jfs/jfs_imap.c
+++ b/fs/jfs/jfs_imap.c
@@ -2844,11 +2844,11 @@
*/
lsn = tblk->lsn;
log = JFS_SBI(tblk->sb)->log;
+ LOGSYNC_LOCK(log, flags);
if (mp->lsn != 0) {
/* inherit older/smaller lsn */
logdiff(difft, lsn, log);
logdiff(diffp, mp->lsn, log);
- LOGSYNC_LOCK(log, flags);
if (difft < diffp) {
mp->lsn = lsn;
/* move mp after tblock in logsync list */
@@ -2860,17 +2860,15 @@
logdiff(diffp, mp->clsn, log);
if (difft > diffp)
mp->clsn = tblk->clsn;
- LOGSYNC_UNLOCK(log, flags);
} else {
mp->log = log;
mp->lsn = lsn;
/* insert mp after tblock in logsync list */
- LOGSYNC_LOCK(log, flags);
log->count++;
list_add(&mp->synclist, &tblk->synclist);
mp->clsn = tblk->clsn;
- LOGSYNC_UNLOCK(log, flags);
}
+ LOGSYNC_UNLOCK(log, flags);
write_metapage(mp);
return (0);
}