This patch converts /proc/pid/fdinfo/fd handling routines to seq-files with
ability to plug in additional fdinfo helpers from other subsystems.
For example files created in eventfd/eventpoll/inotify subsystems might print
out additional information, not just file position and flags.
Still if there no fdinfo helpers registered then the output is well known
pos, flags pair.
Signed-off-by: Cyrill Gorcunov <[email protected]>
---
fs/proc/fd.c | 248 +++++++++++++++++++++++++++++++++++++-----------
fs/proc/fd.h | 1
include/linux/proc_fs.h | 31 ++++++
3 files changed, 224 insertions(+), 56 deletions(-)
Index: linux-2.6.git/fs/proc/fd.c
===================================================================
--- linux-2.6.git.orig/fs/proc/fd.c
+++ linux-2.6.git/fs/proc/fd.c
@@ -6,66 +6,194 @@
#include <linux/namei.h>
#include <linux/pid.h>
#include <linux/security.h>
+#include <linux/file.h>
+#include <linux/seq_file.h>
+#include <linux/spinlock.h>
#include <linux/proc_fs.h>
#include "internal.h"
+#include "fd.h"
-#define PROC_FDINFO_MAX 64
+static LIST_HEAD(fdinfo_helpers);
+static DEFINE_RWLOCK(fdinfo_helpers_lock);
-static int proc_fd_info(struct inode *inode, struct path *path, char *info)
+int proc_register_fdinfo_helper(struct proc_fdinfo_helper *helper)
{
- struct task_struct *task = get_proc_task(inode);
- struct files_struct *files = NULL;
- int fd = proc_fd(inode);
- struct file *file;
+ struct proc_fdinfo_helper *item;
+ int ret = 0;
- if (task) {
- files = get_files_struct(task);
- put_task_struct(task);
+ if (!helper->ops || !helper->probe)
+ return -EINVAL;
+
+ write_lock(&fdinfo_helpers_lock);
+ list_for_each_entry(item, &fdinfo_helpers, list) {
+ if (item == helper) {
+ pr_err("procfs fdinfo helper `%s' is already registered\n",
+ item->name);
+ ret = -EINVAL;
+ break;
+ }
}
+ if (!ret)
+ list_add(&helper->list, &fdinfo_helpers);
+ write_unlock(&fdinfo_helpers_lock);
+ return ret;
+}
- if (files) {
- /*
- * We are not taking a ref to the file structure,
- * so we must hold ->file_lock.
- */
- spin_lock(&files->file_lock);
- file = fcheck_files(files, fd);
+void proc_unregister_fdinfo_helper(struct proc_fdinfo_helper *helper)
+{
+ struct proc_fdinfo_helper *item;
- if (file) {
- unsigned int f_flags;
- struct fdtable *fdt;
+ write_lock(&fdinfo_helpers_lock);
+ list_for_each_entry(item, &fdinfo_helpers, list) {
+ if (item == helper) {
+ list_del(&item->list);
+ break;
+ }
+ }
+ write_unlock(&fdinfo_helpers_lock);
+}
- fdt = files_fdtable(files);
- f_flags = file->f_flags & ~O_CLOEXEC;
- if (close_on_exec(fd, fdt))
- f_flags |= O_CLOEXEC;
-
- if (path) {
- *path = file->f_path;
- path_get(&file->f_path);
- }
+static void assign_fdinfo_helper(struct proc_fdinfo_extra *extra)
+{
+ struct proc_fdinfo_helper *item;
+ read_lock(&fdinfo_helpers_lock);
+ list_for_each_entry(item, &fdinfo_helpers, list) {
+ if (item->probe(extra->fd_file)) {
+ extra->helper = item;
+ break;
+ }
+ }
+ read_unlock(&fdinfo_helpers_lock);
+}
+
+static void *seq_start(struct seq_file *m, loff_t *pos)
+{
+ struct proc_fdinfo_extra *extra = m->private;
+
+ read_lock(&fdinfo_helpers_lock);
+
+ if (*pos > 0)
+ extra->hdr_shown = true;
+
+ return *pos == 0 ? extra :
+ (extra->helper ? extra->helper->ops->start(m, pos) : NULL);
+}
+
+static void seq_stop(struct seq_file *m, void *v)
+{
+ struct proc_fdinfo_extra *extra = m->private;
+
+ if (extra->helper && extra->hdr_shown)
+ extra->helper->ops->stop(m, v);
+
+ read_unlock(&fdinfo_helpers_lock);
+}
+
+static void *seq_next(struct seq_file *m, void *p, loff_t *pos)
+{
+ struct proc_fdinfo_extra *extra = m->private;
+
+ if (extra->helper)
+ return extra->helper->ops->next(m, p, pos);
+
+ ++*pos;
+ return NULL;
+}
+
+static int seq_show(struct seq_file *m, void *v)
+{
+ struct proc_fdinfo_extra *extra = m->private;
+
+ if (extra->helper && extra->hdr_shown)
+ return extra->helper->ops->show(m, v);
+
+ seq_printf(m, "pos:\t%lli\nflags:\t0%o\n",
+ (long long)extra->fd_file->f_pos,
+ extra->f_flags);
+
+ extra->hdr_shown = 1;
+ return 0;
+}
+
+static const struct seq_operations fdinfo_seq_ops = {
+ .start = seq_start,
+ .next = seq_next,
+ .stop = seq_stop,
+ .show = seq_show,
+};
- if (info)
- snprintf(info, PROC_FDINFO_MAX,
- "pos:\t%lli\n"
- "flags:\t0%o\n",
- (long long)file->f_pos,
- f_flags);
+static int seq_fdinfo_open(struct inode *inode, struct file *file)
+{
+ struct files_struct *files = NULL;
+ struct proc_fdinfo_extra *extra;
+ struct task_struct *task;
+ struct seq_file *m;
+ int ret;
+
+ extra = kzalloc(sizeof(*extra), GFP_KERNEL);
+ if (!extra)
+ return -ENOMEM;
+ extra->inode = inode;
+
+ ret = seq_open(file, &fdinfo_seq_ops);
+ if (!ret) {
+ ret = -ENOENT;
+ m = file->private_data;
+ m->private = extra;
+
+ task = get_proc_task(inode);
+ if (task) {
+ files = get_files_struct(task);
+ put_task_struct(task);
+ }
+
+ if (files) {
+ int fd = proc_fd(inode);
+ spin_lock(&files->file_lock);
+ extra->fd_file = fcheck_files(files, fd);
+ if (extra->fd_file) {
+ struct fdtable *fdt = files_fdtable(files);
+
+ extra->f_flags = extra->fd_file->f_flags & ~O_CLOEXEC;
+ if (close_on_exec(fd, fdt))
+ extra->f_flags |= O_CLOEXEC;
+ get_file(extra->fd_file);
+ ret = 0;
+ }
spin_unlock(&files->file_lock);
put_files_struct(files);
- return 0;
- }
- spin_unlock(&files->file_lock);
- put_files_struct(files);
+ if (extra->fd_file)
+ assign_fdinfo_helper(extra);
+ }
}
- return -ENOENT;
+ if (ret)
+ kfree(extra);
+ return ret;
}
+static int seq_fdinfo_release(struct inode *inode, struct file *file)
+{
+ struct seq_file *m = file->private_data;
+ struct proc_fdinfo_extra *extra = m->private;
+
+ put_filp(extra->fd_file);
+ kfree(m->private);
+
+ return seq_release(inode, file);
+}
+
+static const struct file_operations proc_fdinfo_file_operations = {
+ .open = seq_fdinfo_open,
+ .read = seq_read,
+ .llseek = seq_lseek,
+ .release = seq_fdinfo_release,
+};
+
static int tid_fd_revalidate(struct dentry *dentry, struct nameidata *nd)
{
struct files_struct *files;
@@ -120,7 +248,31 @@ static const struct dentry_operations ti
static int proc_fd_link(struct dentry *dentry, struct path *path)
{
- return proc_fd_info(dentry->d_inode, path, NULL);
+ struct inode *inode = dentry->d_inode;
+ struct task_struct *task = get_proc_task(inode);
+ struct files_struct *files = NULL;
+ int fd = proc_fd(inode);
+ struct file *file;
+ int err = -ENOENT;
+
+ if (task) {
+ files = get_files_struct(task);
+ put_task_struct(task);
+ }
+
+ if (files) {
+ spin_lock(&files->file_lock);
+ file = fcheck_files(files, fd);
+ if (file) {
+ *path = file->f_path;
+ path_get(&file->f_path);
+ }
+ spin_unlock(&files->file_lock);
+ put_files_struct(files);
+ err = 0;
+ }
+
+ return err;
}
static struct dentry *
@@ -263,22 +415,6 @@ out_no_task:
return retval;
}
-static ssize_t proc_fdinfo_read(struct file *file, char __user *buf,
- size_t len, loff_t *ppos)
-{
- char tmp[PROC_FDINFO_MAX];
- int err = proc_fd_info(file->f_path.dentry->d_inode, NULL, tmp);
- if (!err)
- err = simple_read_from_buffer(buf, len, ppos, tmp, strlen(tmp));
- return err;
-}
-
-static const struct file_operations proc_fdinfo_file_operations = {
- .open = nonseekable_open,
- .read = proc_fdinfo_read,
- .llseek = no_llseek,
-};
-
static int proc_readfd(struct file *filp, void *dirent, filldir_t filldir)
{
return proc_readfd_common(filp, dirent, filldir, proc_fd_instantiate);
Index: linux-2.6.git/fs/proc/fd.h
===================================================================
--- linux-2.6.git.orig/fs/proc/fd.h
+++ linux-2.6.git/fs/proc/fd.h
@@ -1,6 +1,7 @@
#ifndef __PROCFS_FD_H__
#define __PROCFS_FD_H__
+#include <linux/types.h>
#include <linux/fs.h>
extern const struct file_operations proc_fd_operations;
Index: linux-2.6.git/include/linux/proc_fs.h
===================================================================
--- linux-2.6.git.orig/include/linux/proc_fs.h
+++ linux-2.6.git/include/linux/proc_fs.h
@@ -100,6 +100,25 @@ struct vmcore {
loff_t offset;
};
+struct seq_operations;
+struct proc_fdinfo_helper {
+ struct list_head list;
+ const char *name;
+ const struct seq_operations *ops;
+ int (*probe)(struct file *file);
+ int (*init)(void *private);
+ void (*fini)(void *private);
+};
+
+struct proc_fdinfo_extra {
+ struct proc_fdinfo_helper *helper;
+ struct inode *inode;
+ struct file *fd_file;
+ unsigned int f_flags;
+ void *private;
+ int hdr_shown;
+};
+
#ifdef CONFIG_PROC_FS
extern void proc_root_init(void);
@@ -175,6 +194,9 @@ extern struct proc_dir_entry *proc_net_m
extern struct file *proc_ns_fget(int fd);
+extern int proc_register_fdinfo_helper(struct proc_fdinfo_helper *helper);
+extern void proc_unregister_fdinfo_helper(struct proc_fdinfo_helper *helper);
+
#else
#define proc_net_fops_create(net, name, mode, fops) ({ (void)(mode), NULL; })
@@ -229,6 +251,15 @@ static inline struct file *proc_ns_fget(
return ERR_PTR(-EINVAL);
}
+static inline int proc_register_fdinfo_helper(struct proc_fdinfo_helper *helper)
+{
+ return -EINVAL;
+}
+
+static inline void proc_unregister_fdinfo_helper(struct proc_fdinfo_helper *helper)
+{
+}
+
#endif /* CONFIG_PROC_FS */
#if !defined(CONFIG_PROC_KCORE)
On 05/17/2012 08:07 PM, Cyrill Gorcunov wrote:
> This patch converts /proc/pid/fdinfo/fd handling routines to seq-files with
> ability to plug in additional fdinfo helpers from other subsystems.
>
> For example files created in eventfd/eventpoll/inotify subsystems might print
> out additional information, not just file position and flags.
>
> Still if there no fdinfo helpers registered then the output is well known
> pos, flags pair.
>
> Signed-off-by: Cyrill Gorcunov <[email protected]>
I would split this into two parts -- the 1st one turns fdinfo into seq-files
and the 2nd one adds the fdinfo helpers. This will make the review MUCH simpler.
Thanks,
Pavel
On Thu, May 17, 2012 at 08:32:04PM +0400, Pavel Emelyanov wrote:
>
> I would split this into two parts -- the 1st one turns fdinfo into seq-files
> and the 2nd one adds the fdinfo helpers. This will make the review MUCH simpler.
Yeah, will do and send. Thanks.
Cyrill
On Thu, May 17, 2012 at 09:38:48PM +0400, Cyrill Gorcunov wrote:
> On Thu, May 17, 2012 at 08:32:04PM +0400, Pavel Emelyanov wrote:
> >
> > I would split this into two parts -- the 1st one turns fdinfo into seq-files
> > and the 2nd one adds the fdinfo helpers. This will make the review MUCH simpler.
>
> Yeah, will do and send. Thanks.
>
Here are two patches, hope such split will help in review procedure.
(I pushed them on github as well, so the complete fd.c can be seen
here http://goo.gl/mt4q8 ).
Cyrill