From 25cb5d7a6b37b7bf378b61eac709abe087a03a3d Mon Sep 17 00:00:00 2001 From: Ian Dowse Date: Sun, 30 Nov 2003 23:30:09 +0000 Subject: [PATCH] In dounmount(), only call checkdirs() prior to VFS_UNMOUNT() in the forced unmount case. Otherwise, a file system that is referenced only by process fd_cdir/fd_rdir references to the file system root vnode will be successfully unmounted without the MNT_FORCE flag. The previous behaviour was not compatible with the unmount semantics required by amd(8), so file systems could be unexpectedly unmounted while there were still references to the file system root directory. Reported by: Erez Zadok Approved by: re (scottl) --- sys/kern/vfs_mount.c | 10 +++++++--- 1 file changed, 7 insertions(+), 3 deletions(-) diff --git a/sys/kern/vfs_mount.c b/sys/kern/vfs_mount.c index b265fc313d6..c1bf0b9b900 100644 --- a/sys/kern/vfs_mount.c +++ b/sys/kern/vfs_mount.c @@ -1110,8 +1110,12 @@ dounmount(mp, flags, td) cache_purgevfs(mp); /* remove cache entries for this file sys */ if (mp->mnt_syncer != NULL) vrele(mp->mnt_syncer); - /* Move process cdir/rdir refs on fs root to underlying vnode. */ - if (VFS_ROOT(mp, &fsrootvp) == 0) { + /* + * For forced unmounts, move process cdir/rdir refs on the fs root + * vnode to the covered vnode. For non-forced unmounts we want + * such references to cause an EBUSY error. + */ + if ((flags & MNT_FORCE) && VFS_ROOT(mp, &fsrootvp) == 0) { if (mp->mnt_vnodecovered != NULL) checkdirs(fsrootvp, mp->mnt_vnodecovered); if (fsrootvp == rootvnode) { @@ -1128,7 +1132,7 @@ dounmount(mp, flags, td) vn_finished_write(mp); if (error) { /* Undo cdir/rdir and rootvnode changes made above. */ - if (VFS_ROOT(mp, &fsrootvp) == 0) { + if ((flags & MNT_FORCE) && VFS_ROOT(mp, &fsrootvp) == 0) { if (mp->mnt_vnodecovered != NULL) checkdirs(mp->mnt_vnodecovered, fsrootvp); if (rootvnode == NULL) {