On 2004.03.01 01:54, Neil Brown wrote:
> Another is to add "rootdev" to /proc/*, as in appended patch. Then
> ln -s /proc/self/roodev /dev/root
>
> and providing /proc is mounted, /dev/root will work.
>
> I think I prefer the /proc/self/rootdev approach despite it being the
> bigger patch.
>
> I might try to push it on linux-kernel.
It doesn't work. Here's a version that does:
--- linux-2.6.3/fs/proc/base.c 2004-02-18 04:58:32.000000000 +0100
+++ linux-2.6.3-bk8-mdp/fs/proc/base.c 2004-03-01 15:20:22.000000000 +0100
@@ -50,6 +50,7 @@
PROC_TGID_MEM,
PROC_TGID_CWD,
PROC_TGID_ROOT,
+ PROC_TGID_ROOTDEV,
PROC_TGID_EXE,
PROC_TGID_FD,
PROC_TGID_ENVIRON,
@@ -73,6 +74,7 @@
PROC_TID_MEM,
PROC_TID_CWD,
PROC_TID_ROOT,
+ PROC_TID_ROOTDEV,
PROC_TID_EXE,
PROC_TID_FD,
PROC_TID_ENVIRON,
@@ -115,6 +117,7 @@
E(PROC_TGID_MEM, "mem", S_IFREG|S_IRUSR|S_IWUSR),
E(PROC_TGID_CWD, "cwd", S_IFLNK|S_IRWXUGO),
E(PROC_TGID_ROOT, "root", S_IFLNK|S_IRWXUGO),
+ E(PROC_TGID_ROOTDEV, "rootdev", S_IFBLK|S_IRUSR|S_IWUSR),
E(PROC_TGID_EXE, "exe", S_IFLNK|S_IRWXUGO),
E(PROC_TGID_MOUNTS, "mounts", S_IFREG|S_IRUGO),
#ifdef CONFIG_SECURITY
@@ -137,6 +140,7 @@
E(PROC_TID_MEM, "mem", S_IFREG|S_IRUSR|S_IWUSR),
E(PROC_TID_CWD, "cwd", S_IFLNK|S_IRWXUGO),
E(PROC_TID_ROOT, "root", S_IFLNK|S_IRWXUGO),
+ E(PROC_TID_ROOTDEV, "rootdev", S_IFBLK|S_IRUSR|S_IWUSR),
E(PROC_TID_EXE, "exe", S_IFLNK|S_IRWXUGO),
E(PROC_TID_MOUNTS, "mounts", S_IFREG|S_IRUGO),
#ifdef CONFIG_SECURITY
@@ -771,6 +775,32 @@
.follow_link = proc_pid_follow_link
};
+static int init_pid_rootdev_inode(struct inode *inode)
+{
+ struct fs_struct *fs;
+ struct vfsmount *vmnt;
+ int result = -ENOENT;
+ dev_t rootdev = 0;
+
+ task_lock(proc_task(inode));
+ fs = proc_task(inode)->fs;
+ if(fs)
+ atomic_inc(&fs->count);
+ task_unlock(proc_task(inode));
+ if (fs) {
+ read_lock(&fs->lock);
+ vmnt = mntget(fs->rootmnt);
+ rootdev = vmnt->mnt_sb->s_dev;
+ mntput(vmnt);
+ read_unlock(&fs->lock);
+ result = 0;
+ put_fs_struct(fs);
+ }
+ init_special_inode(inode, inode->i_mode, rootdev);
+
+ return result;
+}
+
static int pid_alive(struct task_struct *p)
{
BUG_ON(p->pids[PIDTYPE_PID].pidptr != &p->pids[PIDTYPE_PID].pid);
@@ -958,7 +988,9 @@
ei->type = ino;
inode->i_uid = 0;
inode->i_gid = 0;
- if (ino == PROC_TGID_INO || ino == PROC_TID_INO || task_dumpable(task)) {
+ if (ino != PROC_TGID_ROOTDEV && ino != PROC_TID_ROOTDEV &&
+ (ino == PROC_TGID_INO || ino == PROC_TID_INO ||
+ task_dumpable(task))) {
inode->i_uid = task->euid;
inode->i_gid = task->egid;
}
@@ -988,7 +1020,10 @@
struct inode *inode = dentry->d_inode;
struct task_struct *task = proc_task(inode);
if (pid_alive(task)) {
- if (proc_type(inode) == PROC_TGID_INO || proc_type(inode) == PROC_TID_INO || task_dumpable(task)) {
+ int ino = proc_type(inode);
+ if (ino != PROC_TGID_ROOTDEV && ino != PROC_TID_ROOTDEV &&
+ (ino == PROC_TGID_INO || ino == PROC_TID_INO ||
+ task_dumpable(task))) {
inode->i_uid = task->euid;
inode->i_gid = task->egid;
} else {
@@ -1319,6 +1354,10 @@
inode->i_op = &proc_pid_link_inode_operations;
ei->op.proc_get_link = proc_root_link;
break;
+ case PROC_TID_ROOTDEV:
+ case PROC_TGID_ROOTDEV:
+ init_pid_rootdev_inode(inode);
+ break;
case PROC_TID_ENVIRON:
case PROC_TGID_ENVIRON:
inode->i_fop = &proc_info_file_operations;
-
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