The patch titled
Subject: fs: use seq_open_private() for proc_mounts
has been added to the -mm tree. Its filename is
fs-use-seq_open_private-for-proc_mounts.patch
This patch should soon appear at
http://ozlabs.org/~akpm/mmots/broken-out/fs-use-seq_open_private-for-proc_mounts.patch
and later at
http://ozlabs.org/~akpm/mmotm/broken-out/fs-use-seq_open_private-for-proc_mounts.patch
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------------------------------------------------------
From: Yann Droneaud <ydroneaud@xxxxxxxxxx>
Subject: fs: use seq_open_private() for proc_mounts
A patchset to remove support for passing pre-allocated struct seq_file to
seq_open(). Such feature is undocumented and prone to error.
In particular, if seq_release() is used in release handler, it will
kfree() a pointer which was not allocated by seq_open().
So this patchset drops support for pre-allocated struct seq_file: it's
only of use in proc_namespace.c and can be easily replaced by using
seq_open_private()/seq_release_private().
Additionally, it documents the use of file->private_data to hold pointer
to struct seq_file by seq_open().
This patch (of 3):
Since patch described below, from v2.6.15-rc1, seq_open() could use a
struct seq_file already allocated by the caller if the pointer to the
structure is stored in file->private_data before calling the function.
Commit 1abe77b0fc4b485927f1f798ae81a752677e1d05
Author: Al Viro <viro@xxxxxxxxxxxxxxxxxx>
Date: Mon Nov 7 17:15:34 2005 -0500
[PATCH] allow callers of seq_open do allocation themselves
Allow caller of seq_open() to kmalloc() seq_file + whatever else they
want and set ->private_data to it. seq_open() will then abstain from
doing allocation itself.
Such behavior is only used by mounts_open_common().
In order to drop support for such uncommon feature, proc_mounts is
converted to use seq_open_private(), which take care of allocating the
proc_mounts structure, making it available through ->private in struct
seq_file.
Conversely, proc_mounts is converted to use seq_release_private(), in
order to release the private structure allocated by seq_open_private().
Then, ->private is used directly instead of proc_mounts() macro to access
to the proc_mounts structure.
Link: http://lkml.kernel.org/r/cover.1433193673.git.ydroneaud@xxxxxxxxxx
Signed-off-by: Yann Droneaud <ydroneaud@xxxxxxxxxx>
Cc: Al Viro <viro@xxxxxxxxxxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
fs/mount.h | 3 ---
fs/namespace.c | 6 +++---
fs/proc_namespace.c | 34 ++++++++++++++++------------------
3 files changed, 19 insertions(+), 24 deletions(-)
diff -puN fs/mount.h~fs-use-seq_open_private-for-proc_mounts fs/mount.h
--- a/fs/mount.h~fs-use-seq_open_private-for-proc_mounts
+++ a/fs/mount.h
@@ -117,7 +117,6 @@ static inline void unlock_mount_hash(voi
}
struct proc_mounts {
- struct seq_file m;
struct mnt_namespace *ns;
struct path root;
int (*show)(struct seq_file *, struct vfsmount *);
@@ -126,8 +125,6 @@ struct proc_mounts {
loff_t cached_index;
};
-#define proc_mounts(p) (container_of((p), struct proc_mounts, m))
-
extern const struct seq_operations mounts_op;
extern bool __is_local_mountpoint(struct dentry *dentry);
diff -puN fs/namespace.c~fs-use-seq_open_private-for-proc_mounts fs/namespace.c
--- a/fs/namespace.c~fs-use-seq_open_private-for-proc_mounts
+++ a/fs/namespace.c
@@ -1215,7 +1215,7 @@ EXPORT_SYMBOL(replace_mount_options);
/* iterator; we want it to have access to namespace_sem, thus here... */
static void *m_start(struct seq_file *m, loff_t *pos)
{
- struct proc_mounts *p = proc_mounts(m);
+ struct proc_mounts *p = m->private;
down_read(&namespace_sem);
if (p->cached_event == p->ns->event) {
@@ -1236,7 +1236,7 @@ static void *m_start(struct seq_file *m,
static void *m_next(struct seq_file *m, void *v, loff_t *pos)
{
- struct proc_mounts *p = proc_mounts(m);
+ struct proc_mounts *p = m->private;
p->cached_mount = seq_list_next(v, &p->ns->list, pos);
p->cached_index = *pos;
@@ -1250,7 +1250,7 @@ static void m_stop(struct seq_file *m, v
static int m_show(struct seq_file *m, void *v)
{
- struct proc_mounts *p = proc_mounts(m);
+ struct proc_mounts *p = m->private;
struct mount *r = list_entry(v, struct mount, mnt_list);
return p->show(m, &r->mnt);
}
diff -puN fs/proc_namespace.c~fs-use-seq_open_private-for-proc_mounts fs/proc_namespace.c
--- a/fs/proc_namespace.c~fs-use-seq_open_private-for-proc_mounts
+++ a/fs/proc_namespace.c
@@ -17,7 +17,8 @@
static unsigned mounts_poll(struct file *file, poll_table *wait)
{
- struct proc_mounts *p = proc_mounts(file->private_data);
+ struct seq_file *m = file->private_data;
+ struct proc_mounts *p = m->private;
struct mnt_namespace *ns = p->ns;
unsigned res = POLLIN | POLLRDNORM;
int event;
@@ -25,8 +26,8 @@ static unsigned mounts_poll(struct file
poll_wait(file, &p->ns->poll, wait);
event = ACCESS_ONCE(ns->event);
- if (p->m.poll_event != event) {
- p->m.poll_event = event;
+ if (m->poll_event != event) {
+ m->poll_event = event;
res |= POLLERR | POLLPRI;
}
@@ -92,7 +93,7 @@ static void show_type(struct seq_file *m
static int show_vfsmnt(struct seq_file *m, struct vfsmount *mnt)
{
- struct proc_mounts *p = proc_mounts(m);
+ struct proc_mounts *p = m->private;
struct mount *r = real_mount(mnt);
int err = 0;
struct path mnt_path = { .dentry = mnt->mnt_root, .mnt = mnt };
@@ -126,7 +127,7 @@ out:
static int show_mountinfo(struct seq_file *m, struct vfsmount *mnt)
{
- struct proc_mounts *p = proc_mounts(m);
+ struct proc_mounts *p = m->private;
struct mount *r = real_mount(mnt);
struct super_block *sb = mnt->mnt_sb;
struct path mnt_path = { .dentry = mnt->mnt_root, .mnt = mnt };
@@ -186,7 +187,7 @@ out:
static int show_vfsstat(struct seq_file *m, struct vfsmount *mnt)
{
- struct proc_mounts *p = proc_mounts(m);
+ struct proc_mounts *p = m->private;
struct mount *r = real_mount(mnt);
struct path mnt_path = { .dentry = mnt->mnt_root, .mnt = mnt };
struct super_block *sb = mnt_path.dentry->d_sb;
@@ -236,6 +237,7 @@ static int mounts_open_common(struct ino
struct mnt_namespace *ns = NULL;
struct path root;
struct proc_mounts *p;
+ struct seq_file *m;
int ret = -EINVAL;
if (!task)
@@ -260,26 +262,21 @@ static int mounts_open_common(struct ino
task_unlock(task);
put_task_struct(task);
- ret = -ENOMEM;
- p = kmalloc(sizeof(struct proc_mounts), GFP_KERNEL);
- if (!p)
+ ret = seq_open_private(file, &mounts_op, sizeof(struct proc_mounts));
+ if (ret)
goto err_put_path;
- file->private_data = &p->m;
- ret = seq_open(file, &mounts_op);
- if (ret)
- goto err_free;
+ m = file->private_data;
+ m->poll_event = ns->event;
+ p = m->private;
p->ns = ns;
p->root = root;
- p->m.poll_event = ns->event;
p->show = show;
p->cached_event = ~0ULL;
return 0;
- err_free:
- kfree(p);
err_put_path:
path_put(&root);
err_put_ns:
@@ -290,10 +287,11 @@ static int mounts_open_common(struct ino
static int mounts_release(struct inode *inode, struct file *file)
{
- struct proc_mounts *p = proc_mounts(file->private_data);
+ struct seq_file *m = file->private_data;
+ struct proc_mounts *p = m->private;
path_put(&p->root);
put_mnt_ns(p->ns);
- return seq_release(inode, file);
+ return seq_release_private(inode, file);
}
static int mounts_open(struct inode *inode, struct file *file)
_
Patches currently in -mm which might be from ydroneaud@xxxxxxxxxx are
fs-use-seq_open_private-for-proc_mounts.patch
fs-allocate-structure-unconditionally-in-seq_open.patch
fs-documents-seq_opens-usage-of-file-private_data.patch
linux-next.patch
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