[src/bouyer-quota2]: src/sys/ufs Do not update disk quotas for snapshot inode...

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

details:   https://anonhg.NetBSD.org/src/rev/f2c0ca5f0501
branches:  bouyer-quota2
changeset: 761167:f2c0ca5f0501
user:      bouyer <bouyer%NetBSD.org@localhost>
date:      Sat Feb 12 19:52:39 2011 +0000

description:
Do not update disk quotas for snapshot inodes, as this may require a
write to the same filesystem, which will trigger a copy on write,
which will trigger another update to the same block.
Set SF_SNAPSHOT just after truncating the snapshot inode, so that this
inode always account for 0 blocks in quotas.

diffstat:

 sys/ufs/ffs/ffs_snapshot.c |  18 ++++++++++--------
 sys/ufs/ufs/ufs_quota.c    |   8 ++++++--
 2 files changed, 16 insertions(+), 10 deletions(-)

diffs (82 lines):

diff -r d3d701306fad -r f2c0ca5f0501 sys/ufs/ffs/ffs_snapshot.c
--- a/sys/ufs/ffs/ffs_snapshot.c        Fri Feb 11 17:28:29 2011 +0000
+++ b/sys/ufs/ffs/ffs_snapshot.c        Sat Feb 12 19:52:39 2011 +0000
@@ -1,4 +1,4 @@
-/*     $NetBSD: ffs_snapshot.c,v 1.102 2010/12/20 00:25:47 matt Exp $  */
+/*     $NetBSD: ffs_snapshot.c,v 1.102.4.1 2011/02/12 19:52:39 bouyer Exp $    */
 
 /*
  * Copyright 2000 Marshall Kirk McKusick. All Rights Reserved.
@@ -38,7 +38,7 @@
  */
 
 #include <sys/cdefs.h>
-__KERNEL_RCSID(0, "$NetBSD: ffs_snapshot.c,v 1.102 2010/12/20 00:25:47 matt Exp $");
+__KERNEL_RCSID(0, "$NetBSD: ffs_snapshot.c,v 1.102.4.1 2011/02/12 19:52:39 bouyer Exp $");
 
 #if defined(_KERNEL_OPT)
 #include "opt_ffs.h"
@@ -214,12 +214,6 @@
        if (error)
                goto out;
        /*
-        * Change inode to snapshot type file.
-        */
-       ip->i_flags |= SF_SNAPSHOT;
-       DIP_ASSIGN(ip, flags, ip->i_flags);
-       ip->i_flag |= IN_CHANGE | IN_UPDATE;
-       /*
         * Copy all the cylinder group maps. Although the
         * filesystem is still active, we hope that only a few
         * cylinder groups will change between now and when we
@@ -408,6 +402,7 @@
        struct buf *ibp, *nbp;
        struct fs *fs = VFSTOUFS(mp)->um_fs;
        struct lwp *l = curlwp;
+       struct inode *ip = VTOI(vp);
 
        /*
         * Check mount, exclusive reference and owner.
@@ -427,6 +422,13 @@
                        return error;
        }
        /*
+        * Change inode to snapshot type file.
+        * Do it now so that allocations below are not recorded in quotas
+        */
+       ip->i_flags |= SF_SNAPSHOT;
+       DIP_ASSIGN(ip, flags, ip->i_flags);
+       ip->i_flag |= IN_CHANGE | IN_UPDATE;
+       /*
         * Write an empty list of preallocated blocks to the end of
         * the snapshot to set size to at least that of the filesystem.
         */
diff -r d3d701306fad -r f2c0ca5f0501 sys/ufs/ufs/ufs_quota.c
--- a/sys/ufs/ufs/ufs_quota.c   Fri Feb 11 17:28:29 2011 +0000
+++ b/sys/ufs/ufs/ufs_quota.c   Sat Feb 12 19:52:39 2011 +0000
@@ -1,4 +1,4 @@
-/*     $NetBSD: ufs_quota.c,v 1.68.4.11 2011/02/09 16:15:01 bouyer Exp $       */
+/*     $NetBSD: ufs_quota.c,v 1.68.4.12 2011/02/12 19:52:40 bouyer Exp $       */
 
 /*
  * Copyright (c) 1982, 1986, 1990, 1993, 1995
@@ -35,7 +35,7 @@
  */
 
 #include <sys/cdefs.h>
-__KERNEL_RCSID(0, "$NetBSD: ufs_quota.c,v 1.68.4.11 2011/02/09 16:15:01 bouyer Exp $");
+__KERNEL_RCSID(0, "$NetBSD: ufs_quota.c,v 1.68.4.12 2011/02/12 19:52:40 bouyer Exp $");
 
 #if defined(_KERNEL_OPT)
 #include "opt_quota.h"
@@ -118,6 +118,10 @@
 int
 chkdq(struct inode *ip, int64_t change, kauth_cred_t cred, int flags)
 {
+       /* do not track snapshot usage, or we will deadlock */
+       if ((ip->i_flags & SF_SNAPSHOT) != 0)
+               return 0;
+
 #ifdef QUOTA
        if (ip->i_ump->um_flags & UFS_QUOTA)
                return chkdq1(ip, change, cred, flags);