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Date: Mon, 17 Sep 2007 11:27:45 -0700
From: Dave Hansen <haveblue@...ibm.com>
To: akpm@...l.org
Cc: linux-kernel@...r.kernel.org, hch@...radead.org,
Dave Hansen <haveblue@...ibm.com>
Subject: [PATCH 20/24] sys_mknodat(): elevate write count for vfs_mknod/create()
This takes care of all of the direct callers of vfs_mknod().
Since a few of these cases also handle normal file creation
as well, this also covers some calls to vfs_create().
So that we don't have to make three mnt_want/drop_write()
calls inside of the switch statement, we move some of its
logic outside of the switch.
Signed-off-by: Dave Hansen <haveblue@...ibm.com>
---
lxc-dave/fs/namei.c | 32 +++++++++++++++++++++-----------
lxc-dave/fs/nfsd/vfs.c | 4 ++++
lxc-dave/net/unix/af_unix.c | 4 ++++
3 files changed, 29 insertions(+), 11 deletions(-)
diff -puN fs/namei.c~sys-mknodat-elevate-write-count-for-vfs-mknod-create fs/namei.c
--- lxc/fs/namei.c~sys-mknodat-elevate-write-count-for-vfs-mknod-create 2007-09-17 09:44:08.000000000 -0700
+++ lxc-dave/fs/namei.c 2007-09-17 09:44:08.000000000 -0700
@@ -1970,12 +1970,25 @@ asmlinkage long sys_mknodat(int dfd, con
if (error)
goto out;
dentry = lookup_create(&nd, 0);
- error = PTR_ERR(dentry);
-
+ if (IS_ERR(dentry)) {
+ error = PTR_ERR(dentry);
+ goto out_unlock;
+ }
if (!IS_POSIXACL(nd.dentry->d_inode))
mode &= ~current->fs->umask;
- if (!IS_ERR(dentry)) {
- switch (mode & S_IFMT) {
+ if (S_ISDIR(mode)) {
+ error = -EPERM;
+ goto out_dput;
+ }
+ if (!S_ISREG(mode) && !S_ISCHR(mode) && !S_ISBLK(mode) &&
+ !S_ISFIFO(mode) && !S_ISSOCK(mode) && mode != 0) {
+ error = -EINVAL;
+ goto out_dput;
+ }
+ error = mnt_want_write(nd.mnt);
+ if (error)
+ goto out_dput;
+ switch (mode & S_IFMT) {
case 0: case S_IFREG:
error = vfs_create(nd.dentry->d_inode,dentry,mode,&nd);
break;
@@ -1986,14 +1999,11 @@ asmlinkage long sys_mknodat(int dfd, con
case S_IFIFO: case S_IFSOCK:
error = vfs_mknod(nd.dentry->d_inode,dentry,mode,0);
break;
- case S_IFDIR:
- error = -EPERM;
- break;
- default:
- error = -EINVAL;
- }
- dput(dentry);
}
+ mnt_drop_write(nd.mnt);
+out_dput:
+ dput(dentry);
+out_unlock:
mutex_unlock(&nd.dentry->d_inode->i_mutex);
path_release(&nd);
out:
diff -puN fs/nfsd/vfs.c~sys-mknodat-elevate-write-count-for-vfs-mknod-create fs/nfsd/vfs.c
--- lxc/fs/nfsd/vfs.c~sys-mknodat-elevate-write-count-for-vfs-mknod-create 2007-09-17 09:44:08.000000000 -0700
+++ lxc-dave/fs/nfsd/vfs.c 2007-09-17 09:44:08.000000000 -0700
@@ -1233,7 +1233,11 @@ nfsd_create(struct svc_rqst *rqstp, stru
case S_IFBLK:
case S_IFIFO:
case S_IFSOCK:
+ host_err = mnt_want_write(fhp->fh_export->ex_mnt);
+ if (host_err)
+ break;
host_err = vfs_mknod(dirp, dchild, iap->ia_mode, rdev);
+ mnt_drop_write(fhp->fh_export->ex_mnt);
break;
default:
printk("nfsd: bad file type %o in nfsd_create\n", type);
diff -puN net/unix/af_unix.c~sys-mknodat-elevate-write-count-for-vfs-mknod-create net/unix/af_unix.c
--- lxc/net/unix/af_unix.c~sys-mknodat-elevate-write-count-for-vfs-mknod-create 2007-09-17 09:44:08.000000000 -0700
+++ lxc-dave/net/unix/af_unix.c 2007-09-17 09:44:08.000000000 -0700
@@ -842,7 +842,11 @@ static int unix_bind(struct socket *sock
*/
mode = S_IFSOCK |
(SOCK_INODE(sock)->i_mode & ~current->fs->umask);
+ err = mnt_want_write(nd.mnt);
+ if (err)
+ goto out_mknod_dput;
err = vfs_mknod(nd.dentry->d_inode, dentry, mode, 0);
+ mnt_drop_write(nd.mnt);
if (err)
goto out_mknod_dput;
mutex_unlock(&nd.dentry->d_inode->i_mutex);
_
-
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