[src/trunk]: src/sys/kern Wapbl_register_deallocation(): the taken reader loc...

[hannken <hannken%NetBSD.org@localhost>]

details:   https://anonhg.NetBSD.org/src/rev/31802444a92d
branches:  trunk
changeset: 758582:31802444a92d
user:      hannken <hannken%NetBSD.org@localhost>
date:      Tue Nov 09 16:30:26 2010 +0000

description:
Wapbl_register_deallocation(): the taken reader lock is not sufficient to
protect wl_dealloc* members.  Take the mutex here and change the lock
requirements of these fields to "writer lock or mutex".

This error lead to file system corruption and "freeing free block" panics.

diffstat:

 sys/kern/vfs_wapbl.c |  13 ++++++++-----
 1 files changed, 8 insertions(+), 5 deletions(-)

diffs (55 lines):

diff -r 2f2e34b1757d -r 31802444a92d sys/kern/vfs_wapbl.c
--- a/sys/kern/vfs_wapbl.c      Tue Nov 09 15:26:41 2010 +0000
+++ b/sys/kern/vfs_wapbl.c      Tue Nov 09 16:30:26 2010 +0000
@@ -1,4 +1,4 @@
-/*     $NetBSD: vfs_wapbl.c,v 1.37 2010/09/10 10:14:55 drochner Exp $  */
+/*     $NetBSD: vfs_wapbl.c,v 1.38 2010/11/09 16:30:26 hannken Exp $   */
 
 /*-
  * Copyright (c) 2003, 2008, 2009 The NetBSD Foundation, Inc.
@@ -36,7 +36,7 @@
 #define WAPBL_INTERNAL
 
 #include <sys/cdefs.h>
-__KERNEL_RCSID(0, "$NetBSD: vfs_wapbl.c,v 1.37 2010/09/10 10:14:55 drochner Exp $");
+__KERNEL_RCSID(0, "$NetBSD: vfs_wapbl.c,v 1.38 2010/11/09 16:30:26 hannken Exp $");
 
 #include <sys/param.h>
 #include <sys/bitops.h>
@@ -104,6 +104,7 @@
  *             r = read-only after init
  *             l = rwlock held
  *             m = mutex held
+ *             lm = rwlock held writing or mutex held
  *             u = unlocked access ok
  *             b = bufcache_lock held
  */
@@ -173,9 +174,9 @@
        size_t wl_unsynced_bufbytes; /* Byte count of unsynced buffers */
 #endif
 
-       daddr_t *wl_deallocblks;/* l:   address of block */
-       int *wl_dealloclens;    /* l:   size of block */
-       int wl_dealloccnt;      /* l:   total count */
+       daddr_t *wl_deallocblks;/* lm:  address of block */
+       int *wl_dealloclens;    /* lm:  size of block */
+       int wl_dealloccnt;      /* lm:  total count */
        int wl_dealloclim;      /* l:   max count */
 
        /* hashtable of inode numbers for allocated but unlinked inodes */
@@ -1672,6 +1673,7 @@
 
        wapbl_jlock_assert(wl);
 
+       mutex_enter(&wl->wl_mtx);
        /* XXX should eventually instead tie this into resource estimation */
        /*
         * XXX this panic needs locking/mutex analysis and the
@@ -1686,6 +1688,7 @@
        wl->wl_dealloccnt++;
        WAPBL_PRINTF(WAPBL_PRINT_ALLOC,
            ("wapbl_register_deallocation: blk=%"PRId64" len=%d\n", blk, len));
+       mutex_exit(&wl->wl_mtx);
 }
 
 /****************************************************************/