[PATCH] 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>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>

diff --git a/fs/jfs/jfs_dmap.c b/fs/jfs/jfs_dmap.c
index 2967b73..79b5404 100644 (file)
--- a/fs/jfs/jfs_dmap.c
+++ b/fs/jfs/jfs_dmap.c
@@ -532,10 +532,10 @@ dbUpdatePMap(struct inode *ipbmap,
 
                lastlblkno = lblkno;
 
+               LOGSYNC_LOCK(log, flags);
                if (mp->lsn != 0) {
                        /* inherit older/smaller lsn */
                        logdiff(diffp, mp->lsn, log);
-                       LOGSYNC_LOCK(log, flags);
                        if (difft < diffp) {
                                mp->lsn = lsn;
 
@@ -548,20 +548,17 @@ dbUpdatePMap(struct inode *ipbmap,
                        logdiff(diffp, mp->clsn, log);
                        if (difft > diffp)
                                mp->clsn = tblk->clsn;
-                       LOGSYNC_UNLOCK(log, flags);
                } else {
                        mp->log = log;
                        mp->lsn = lsn;
 
                        /* insert bp 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 the last buffer. */

diff --git a/fs/jfs/jfs_imap.c b/fs/jfs/jfs_imap.c
index 31b4aa1..4efa0d0 100644 (file)
--- a/fs/jfs/jfs_imap.c
+++ b/fs/jfs/jfs_imap.c
@@ -2844,11 +2844,11 @@ diUpdatePMap(struct inode *ipimap,
         */
        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 @@ diUpdatePMap(struct inode *ipimap,
                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);
 }