procfs: Use the proc generic infrastructure for proc/self.

I had visions at one point of splitting proc into two filesystems.  If
that had happened proc/self being the the part of proc that actually deals
with pids would have been a nice cleanup.  As it is proc/self requires
a lot of unnecessary infrastructure for a single file.

The only user visible change is that a mounted /proc for a pid namespace
that is dead now shows a broken proc symlink, instead of being completely
invisible.  I don't think anyone will notice or care.

Signed-off-by: Eric W. Biederman <ebiederm@xmission.com>

diff --git a/fs/proc/Makefile b/fs/proc/Makefile
index 99349ef..981b056 100644 (file)
--- a/fs/proc/Makefile
+++ b/fs/proc/Makefile
@@ -21,6 +21,7 @@ proc-y        += uptime.o
 proc-y += version.o
 proc-y += softirqs.o
 proc-y += namespaces.o
+proc-y += self.o
 proc-$(CONFIG_PROC_SYSCTL)     += proc_sysctl.o
 proc-$(CONFIG_NET)             += proc_net.o
 proc-$(CONFIG_PROC_KCORE)      += kcore.o

diff --git a/fs/proc/base.c b/fs/proc/base.c
index 144a967..cbe454e 100644 (file)
--- a/fs/proc/base.c
+++ b/fs/proc/base.c
@@ -2237,146 +2237,6 @@ static const struct file_operations proc_coredump_filter_operations = {
 };
 #endif
 
-/*
- * /proc/self:
- */
-static int proc_self_readlink(struct dentry *dentry, char __user *buffer,
-                             int buflen)
-{
-       struct pid_namespace *ns = dentry->d_sb->s_fs_info;
-       pid_t tgid = task_tgid_nr_ns(current, ns);
-       char tmp[PROC_NUMBUF];
-       if (!tgid)
-               return -ENOENT;
-       sprintf(tmp, "%d", tgid);
-       return vfs_readlink(dentry,buffer,buflen,tmp);
-}
-
-static void *proc_self_follow_link(struct dentry *dentry, struct nameidata *nd)
-{
-       struct pid_namespace *ns = dentry->d_sb->s_fs_info;
-       pid_t tgid = task_tgid_nr_ns(current, ns);
-       char *name = ERR_PTR(-ENOENT);
-       if (tgid) {
-               /* 11 for max length of signed int in decimal + NULL term */
-               name = kmalloc(12, GFP_KERNEL);
-               if (!name)
-                       name = ERR_PTR(-ENOMEM);
-               else
-                       sprintf(name, "%d", tgid);
-       }
-       nd_set_link(nd, name);
-       return NULL;
-}
-
-static void proc_self_put_link(struct dentry *dentry, struct nameidata *nd,
-                               void *cookie)
-{
-       char *s = nd_get_link(nd);
-       if (!IS_ERR(s))
-               kfree(s);
-}
-
-static const struct inode_operations proc_self_inode_operations = {
-       .readlink       = proc_self_readlink,
-       .follow_link    = proc_self_follow_link,
-       .put_link       = proc_self_put_link,
-};
-
-/*
- * proc base
- *
- * These are the directory entries in the root directory of /proc
- * that properly belong to the /proc filesystem, as they describe
- * describe something that is process related.
- */
-static const struct pid_entry proc_base_stuff[] = {
-       NOD("self", S_IFLNK|S_IRWXUGO,
-               &proc_self_inode_operations, NULL, {}),
-};
-
-static struct dentry *proc_base_instantiate(struct inode *dir,
-       struct dentry *dentry, struct task_struct *task, const void *ptr)
-{
-       const struct pid_entry *p = ptr;
-       struct inode *inode;
-       struct proc_inode *ei;
-       struct dentry *error;
-
-       /* Allocate the inode */
-       error = ERR_PTR(-ENOMEM);
-       inode = new_inode(dir->i_sb);
-       if (!inode)
-               goto out;
-
-       /* Initialize the inode */
-       ei = PROC_I(inode);
-       inode->i_ino = get_next_ino();
-       inode->i_mtime = inode->i_atime = inode->i_ctime = CURRENT_TIME;
-
-       /*
-        * grab the reference to the task.
-        */
-       ei->pid = get_task_pid(task, PIDTYPE_PID);
-       if (!ei->pid)
-               goto out_iput;
-
-       inode->i_mode = p->mode;
-       if (S_ISDIR(inode->i_mode))
-               set_nlink(inode, 2);
-       if (S_ISLNK(inode->i_mode))
-               inode->i_size = 64;
-       if (p->iop)
-               inode->i_op = p->iop;
-       if (p->fop)
-               inode->i_fop = p->fop;
-       ei->op = p->op;
-       d_add(dentry, inode);
-       error = NULL;
-out:
-       return error;
-out_iput:
-       iput(inode);
-       goto out;
-}
-
-static struct dentry *proc_base_lookup(struct inode *dir, struct dentry *dentry)
-{
-       struct dentry *error;
-       struct task_struct *task = get_proc_task(dir);
-       const struct pid_entry *p, *last;
-
-       error = ERR_PTR(-ENOENT);
-
-       if (!task)
-               goto out_no_task;
-
-       /* Lookup the directory entry */
-       last = &proc_base_stuff[ARRAY_SIZE(proc_base_stuff) - 1];
-       for (p = proc_base_stuff; p <= last; p++) {
-               if (p->len != dentry->d_name.len)
-                       continue;
-               if (!memcmp(dentry->d_name.name, p->name, p->len))
-                       break;
-       }
-       if (p > last)
-               goto out;
-
-       error = proc_base_instantiate(dir, dentry, task, p);
-
-out:
-       put_task_struct(task);
-out_no_task:
-       return error;
-}
-
-static int proc_base_fill_cache(struct file *filp, void *dirent,
-       filldir_t filldir, struct task_struct *task, const struct pid_entry *p)
-{
-       return proc_fill_cache(filp, dirent, filldir, p->name, p->len,
-                               proc_base_instantiate, task, p);
-}
-
 #ifdef CONFIG_TASK_IO_ACCOUNTING
 static int do_io_accounting(struct task_struct *task, char *buffer, int whole)
 {
@@ -2767,15 +2627,11 @@ out:
 
 struct dentry *proc_pid_lookup(struct inode *dir, struct dentry * dentry, unsigned int flags)
 {
-       struct dentry *result;
+       struct dentry *result = NULL;
        struct task_struct *task;
        unsigned tgid;
        struct pid_namespace *ns;
 
-       result = proc_base_lookup(dir, dentry);
-       if (!IS_ERR(result) || PTR_ERR(result) != -ENOENT)
-               goto out;
-
        tgid = name_to_int(dentry);
        if (tgid == ~0U)
                goto out;
@@ -2838,7 +2694,7 @@ retry:
        return iter;
 }
 
-#define TGID_OFFSET (FIRST_PROCESS_ENTRY + ARRAY_SIZE(proc_base_stuff))
+#define TGID_OFFSET (FIRST_PROCESS_ENTRY)
 
 static int proc_pid_fill_cache(struct file *filp, void *dirent, filldir_t filldir,
        struct tgid_iter iter)
@@ -2872,12 +2728,6 @@ int proc_pid_readdir(struct file * filp, void * dirent, filldir_t filldir)
        if (!reaper)
                goto out_no_task;
 
-       for (; nr < ARRAY_SIZE(proc_base_stuff); filp->f_pos++, nr++) {
-               const struct pid_entry *p = &proc_base_stuff[nr];
-               if (proc_base_fill_cache(filp, dirent, filldir, reaper, p) < 0)
-                       goto out;
-       }
-
        ns = filp->f_dentry->d_sb->s_fs_info;
        iter.task = NULL;
        iter.tgid = filp->f_pos - TGID_OFFSET;

diff --git a/fs/proc/internal.h b/fs/proc/internal.h
index 43973b0..252544c 100644 (file)
--- a/fs/proc/internal.h
+++ b/fs/proc/internal.h
@@ -15,6 +15,7 @@ struct  ctl_table_header;
 struct  mempolicy;
 
 extern struct proc_dir_entry proc_root;
+extern void proc_self_init(void);
 #ifdef CONFIG_PROC_SYSCTL
 extern int proc_sys_init(void);
 extern void sysctl_head_put(struct ctl_table_header *head);

diff --git a/fs/proc/root.c b/fs/proc/root.c
index 9889a92..5da9849 100644 (file)
--- a/fs/proc/root.c
+++ b/fs/proc/root.c
@@ -169,6 +169,7 @@ void __init proc_root_init(void)
                return;
        }
 
+       proc_self_init();
        proc_symlink("mounts", NULL, "self/mounts");
 
        proc_net_init();

diff --git a/fs/proc/self.c b/fs/proc/self.c
new file mode 100644 (file)
index 0000000..aa5cc3b
--- /dev/null
+++ b/fs/proc/self.c
@@ -0,0 +1,59 @@
+#include <linux/proc_fs.h>
+#include <linux/sched.h>
+#include <linux/namei.h>
+
+/*
+ * /proc/self:
+ */
+static int proc_self_readlink(struct dentry *dentry, char __user *buffer,
+                             int buflen)
+{
+       struct pid_namespace *ns = dentry->d_sb->s_fs_info;
+       pid_t tgid = task_tgid_nr_ns(current, ns);
+       char tmp[PROC_NUMBUF];
+       if (!tgid)
+               return -ENOENT;
+       sprintf(tmp, "%d", tgid);
+       return vfs_readlink(dentry,buffer,buflen,tmp);
+}
+
+static void *proc_self_follow_link(struct dentry *dentry, struct nameidata *nd)
+{
+       struct pid_namespace *ns = dentry->d_sb->s_fs_info;
+       pid_t tgid = task_tgid_nr_ns(current, ns);
+       char *name = ERR_PTR(-ENOENT);
+       if (tgid) {
+               /* 11 for max length of signed int in decimal + NULL term */
+               name = kmalloc(12, GFP_KERNEL);
+               if (!name)
+                       name = ERR_PTR(-ENOMEM);
+               else
+                       sprintf(name, "%d", tgid);
+       }
+       nd_set_link(nd, name);
+       return NULL;
+}
+
+static void proc_self_put_link(struct dentry *dentry, struct nameidata *nd,
+                               void *cookie)
+{
+       char *s = nd_get_link(nd);
+       if (!IS_ERR(s))
+               kfree(s);
+}
+
+static const struct inode_operations proc_self_inode_operations = {
+       .readlink       = proc_self_readlink,
+       .follow_link    = proc_self_follow_link,
+       .put_link       = proc_self_put_link,
+};
+
+void __init proc_self_init(void)
+{
+       struct proc_dir_entry *proc_self_symlink;
+       mode_t mode;
+
+       mode = S_IFLNK | S_IRWXUGO;
+       proc_self_symlink = proc_create("self", mode, NULL, NULL );
+       proc_self_symlink->proc_iops = &proc_self_inode_operations;
+}