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Message-Id: <1353083750-3621-1-git-send-email-ebiederm@xmission.com>
Date: Fri, 16 Nov 2012 08:35:40 -0800
From: "Eric W. Biederman" <ebiederm@...ssion.com>
To: Linux Containers <containers@...ts.linux-foundation.org>
Cc: <linux-kernel@...r.kernel.org>, Oleg Nesterov <oleg@...sign.ru>,
Serge Hallyn <serge@...lyn.com>,
Gao feng <gaofeng@...fujitsu.com>,
Andrew Morton <akpm@...ux-foundation.org>,
"Eric W. Biederman" <ebiederm@...ssion.com>
Subject: [PATCH 01/11] procfs: Use the proc generic infrastructure for proc/self.
From: "Eric W. Biederman" <ebiederm@...ssion.com>
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@...ssion.com>
---
fs/proc/Makefile | 1 +
fs/proc/base.c | 154 +---------------------------------------------------
fs/proc/internal.h | 1 +
fs/proc/root.c | 1 +
fs/proc/self.c | 59 ++++++++++++++++++++
5 files changed, 64 insertions(+), 152 deletions(-)
create mode 100644 fs/proc/self.c
diff --git a/fs/proc/Makefile b/fs/proc/Makefile
index 99349ef..981b056 100644
--- 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
--- 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
--- 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
--- 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
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;
+}
--
1.7.5.4
--
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