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fs: scale mntget/mntput

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The problem that this patch aims to fix is vfsmount refcounting scalability.
We need to take a reference on the vfsmount for every successful path lookup,
which often go to the same mount point.

The fundamental difficulty is that a "simple" reference count can never be made
scalable, because any time a reference is dropped, we must check whether that
was the last reference. To do that requires communication with all other CPUs
that may have taken a reference count.

We can make refcounts more scalable in a couple of ways, involving keeping
distributed counters, and checking for the global-zero condition less
frequently.

- check the global sum once every interval (this will delay zero detection
  for some interval, so it's probably a showstopper for vfsmounts).

- keep a local count and only taking the global sum when local reaches 0 (this
  is difficult for vfsmounts, because we can't hold preempt off for the life of
  a reference, so a counter would need to be per-thread or tied strongly to a
  particular CPU which requires more locking).

- keep a local difference of increments and decrements, which allows us to sum
  the total difference and hence find the refcount when summing all CPUs. Then,
  keep a single integer "long" refcount for slow and long lasting references,
  and only take the global sum of local counters when the long refcount is 0.

This last scheme is what I implemented here. Attached mounts and process root
and working directory references are "long" references, and everything else is
a short reference.

This allows scalable vfsmount references during path walking over mounted
subtrees and unattached (lazy umounted) mounts with processes still running
in them.

This results in one fewer atomic op in the fastpath: mntget is now just a
per-CPU inc, rather than an atomic inc; and mntput just requires a spinlock
and non-atomic decrement in the common case. However code is otherwise bigger
and heavier, so single threaded performance is basically a wash.

Signed-off-by: Nick Piggin <npiggin@kernel.dk>
This commit is contained in:
Nick Piggin 2011-01-07 17:50:11 +11:00
parent c6653a838b
commit b3e19d924b
13 changed files with 285 additions and 100 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

2
arch/ia64/kernel/perfmon.c
View File

@ -1542,7 +1542,7 @@ pfm_exit_smpl_buffer(pfm_buffer_fmt_t *fmt)
* any operations on the root directory. However, we need a non-trivial
* d_name - pfm: will go nicely and kill the special-casing in procfs.
*/
static struct vfsmount *pfmfs_mnt;
static struct vfsmount *pfmfs_mnt __read_mostly;
static int __init
init_pfm_fs(void)

2
drivers/mtd/mtdchar.c
View File

@ -1201,7 +1201,7 @@ err_unregister_chdev:
static void __exit cleanup_mtdchar(void)
{
unregister_mtd_user(&mtdchar_notifier);
mntput(mtd_inode_mnt);
mntput_long(mtd_inode_mnt);
unregister_filesystem(&mtd_inodefs_type);
__unregister_chrdev(MTD_CHAR_MAJOR, 0, 1 << MINORBITS, "mtd");
}

2
fs/anon_inodes.c
View File

@ -232,7 +232,7 @@ static int __init anon_inode_init(void)
return 0;
err_mntput:
mntput(anon_inode_mnt);
mntput_long(anon_inode_mnt);
err_unregister_filesystem:
unregister_filesystem(&anon_inode_fs_type);
err_exit:

26
fs/fs_struct.c
View File

@ -17,11 +17,11 @@ void set_fs_root(struct fs_struct *fs, struct path *path)
write_seqcount_begin(&fs->seq);
old_root = fs->root;
fs->root = *path;
path_get(path);
path_get_long(path);
write_seqcount_end(&fs->seq);
spin_unlock(&fs->lock);
if (old_root.dentry)
path_put(&old_root);
path_put_long(&old_root);
}
/*
@ -36,12 +36,12 @@ void set_fs_pwd(struct fs_struct *fs, struct path *path)
write_seqcount_begin(&fs->seq);
old_pwd = fs->pwd;
fs->pwd = *path;
path_get(path);
path_get_long(path);
write_seqcount_end(&fs->seq);
spin_unlock(&fs->lock);
if (old_pwd.dentry)
path_put(&old_pwd);
path_put_long(&old_pwd);
}
void chroot_fs_refs(struct path *old_root, struct path *new_root)
@ -59,13 +59,13 @@ void chroot_fs_refs(struct path *old_root, struct path *new_root)
write_seqcount_begin(&fs->seq);
if (fs->root.dentry == old_root->dentry
&& fs->root.mnt == old_root->mnt) {
path_get(new_root);
path_get_long(new_root);
fs->root = *new_root;
count++;
}
if (fs->pwd.dentry == old_root->dentry
&& fs->pwd.mnt == old_root->mnt) {
path_get(new_root);
path_get_long(new_root);
fs->pwd = *new_root;
count++;
}
@ -76,13 +76,13 @@ void chroot_fs_refs(struct path *old_root, struct path *new_root)
} while_each_thread(g, p);
read_unlock(&tasklist_lock);
while (count--)
path_put(old_root);
path_put_long(old_root);
}
void free_fs_struct(struct fs_struct *fs)
{
path_put(&fs->root);
path_put(&fs->pwd);
path_put_long(&fs->root);
path_put_long(&fs->pwd);
kmem_cache_free(fs_cachep, fs);
}
@ -115,7 +115,13 @@ struct fs_struct *copy_fs_struct(struct fs_struct *old)
spin_lock_init(&fs->lock);
seqcount_init(&fs->seq);
fs->umask = old->umask;
get_fs_root_and_pwd(old, &fs->root, &fs->pwd);
spin_lock(&old->lock);
fs->root = old->root;
path_get_long(&fs->root);
fs->pwd = old->pwd;
path_get_long(&fs->pwd);
spin_unlock(&old->lock);
}
return fs;
}

1
fs/internal.h
View File

@ -63,6 +63,7 @@ extern int copy_mount_string(const void __user *, char **);
extern void free_vfsmnt(struct vfsmount *);
extern struct vfsmount *alloc_vfsmnt(const char *);
extern unsigned int mnt_get_count(struct vfsmount *mnt);
extern struct vfsmount *__lookup_mnt(struct vfsmount *, struct dentry *, int);
extern void mnt_set_mountpoint(struct vfsmount *, struct dentry *,
struct vfsmount *);

24
fs/namei.c
View File

@ -367,6 +367,18 @@ void path_get(struct path *path)
}
EXPORT_SYMBOL(path_get);
/**
* path_get_long - get a long reference to a path
* @path: path to get the reference to
*
* Given a path increment the reference count to the dentry and the vfsmount.
*/
void path_get_long(struct path *path)
{
mntget_long(path->mnt);
dget(path->dentry);
}
/**
* path_put - put a reference to a path
* @path: path to put the reference to
@ -380,6 +392,18 @@ void path_put(struct path *path)
}
EXPORT_SYMBOL(path_put);
/**
* path_put_long - put a long reference to a path
* @path: path to put the reference to
*
* Given a path decrement the reference count to the dentry and the vfsmount.
*/
void path_put_long(struct path *path)
{
dput(path->dentry);
mntput_long(path->mnt);
}
/**
* nameidata_drop_rcu - drop this nameidata out of rcu-walk
* @nd: nameidata pathwalk data to drop

246
fs/namespace.c
View File

@ -138,6 +138,64 @@ void mnt_release_group_id(struct vfsmount *mnt)
mnt->mnt_group_id = 0;
}
/*
* vfsmount lock must be held for read
*/
static inline void mnt_add_count(struct vfsmount *mnt, int n)
{
#ifdef CONFIG_SMP
this_cpu_add(mnt->mnt_pcp->mnt_count, n);
#else
preempt_disable();
mnt->mnt_count += n;
preempt_enable();
#endif
}
static inline void mnt_set_count(struct vfsmount *mnt, int n)
{
#ifdef CONFIG_SMP
this_cpu_write(mnt->mnt_pcp->mnt_count, n);
#else
mnt->mnt_count = n;
#endif
}
/*
* vfsmount lock must be held for read
*/
static inline void mnt_inc_count(struct vfsmount *mnt)
{
mnt_add_count(mnt, 1);
}
/*
* vfsmount lock must be held for read
*/
static inline void mnt_dec_count(struct vfsmount *mnt)
{
mnt_add_count(mnt, -1);
}
/*
* vfsmount lock must be held for write
*/
unsigned int mnt_get_count(struct vfsmount *mnt)
{
#ifdef CONFIG_SMP
unsigned int count = atomic_read(&mnt->mnt_longrefs);
int cpu;
for_each_possible_cpu(cpu) {
count += per_cpu_ptr(mnt->mnt_pcp, cpu)->mnt_count;
}
return count;
#else
return mnt->mnt_count;
#endif
}
struct vfsmount *alloc_vfsmnt(const char *name)
{
struct vfsmount *mnt = kmem_cache_zalloc(mnt_cache, GFP_KERNEL);
@ -154,7 +212,17 @@ struct vfsmount *alloc_vfsmnt(const char *name)
goto out_free_id;
}
atomic_set(&mnt->mnt_count, 1);
#ifdef CONFIG_SMP
mnt->mnt_pcp = alloc_percpu(struct mnt_pcp);
if (!mnt->mnt_pcp)
goto out_free_devname;
atomic_set(&mnt->mnt_longrefs, 1);
#else
mnt->mnt_count = 1;
mnt->mnt_writers = 0;
#endif
INIT_LIST_HEAD(&mnt->mnt_hash);
INIT_LIST_HEAD(&mnt->mnt_child);
INIT_LIST_HEAD(&mnt->mnt_mounts);
@ -165,13 +233,6 @@ struct vfsmount *alloc_vfsmnt(const char *name)
INIT_LIST_HEAD(&mnt->mnt_slave);
#ifdef CONFIG_FSNOTIFY
INIT_HLIST_HEAD(&mnt->mnt_fsnotify_marks);
#endif
#ifdef CONFIG_SMP
mnt->mnt_writers = alloc_percpu(int);
if (!mnt->mnt_writers)
goto out_free_devname;
#else
mnt->mnt_writers = 0;
#endif
}
return mnt;
@ -219,7 +280,7 @@ EXPORT_SYMBOL_GPL(__mnt_is_readonly);
static inline void mnt_inc_writers(struct vfsmount *mnt)
{
#ifdef CONFIG_SMP
(*per_cpu_ptr(mnt->mnt_writers, smp_processor_id()))++;
this_cpu_inc(mnt->mnt_pcp->mnt_writers);
#else
mnt->mnt_writers++;
#endif
@ -228,7 +289,7 @@ static inline void mnt_inc_writers(struct vfsmount *mnt)
static inline void mnt_dec_writers(struct vfsmount *mnt)
{
#ifdef CONFIG_SMP
(*per_cpu_ptr(mnt->mnt_writers, smp_processor_id()))--;
this_cpu_dec(mnt->mnt_pcp->mnt_writers);
#else
mnt->mnt_writers--;
#endif
@ -241,7 +302,7 @@ static unsigned int mnt_get_writers(struct vfsmount *mnt)
int cpu;
for_each_possible_cpu(cpu) {
count += *per_cpu_ptr(mnt->mnt_writers, cpu);
count += per_cpu_ptr(mnt->mnt_pcp, cpu)->mnt_writers;
}
return count;
@ -418,7 +479,7 @@ void free_vfsmnt(struct vfsmount *mnt)
kfree(mnt->mnt_devname);
mnt_free_id(mnt);
#ifdef CONFIG_SMP
free_percpu(mnt->mnt_writers);
free_percpu(mnt->mnt_pcp);
#endif
kmem_cache_free(mnt_cache, mnt);
}
@ -652,9 +713,10 @@ static struct vfsmount *clone_mnt(struct vfsmount *old, struct dentry *root,
return NULL;
}
static inline void __mntput(struct vfsmount *mnt)
static inline void mntfree(struct vfsmount *mnt)
{
struct super_block *sb = mnt->mnt_sb;
/*
* This probably indicates that somebody messed
* up a mnt_want/drop_write() pair. If this
@ -662,8 +724,8 @@ static inline void __mntput(struct vfsmount *mnt)
* to make r/w->r/o transitions.
*/
/*
* atomic_dec_and_lock() used to deal with ->mnt_count decrements
* provides barriers, so mnt_get_writers() below is safe. AV
* The locking used to deal with mnt_count decrement provides barriers,
* so mnt_get_writers() below is safe.
*/
WARN_ON(mnt_get_writers(mnt));
fsnotify_vfsmount_delete(mnt);
@ -672,28 +734,113 @@ static inline void __mntput(struct vfsmount *mnt)
deactivate_super(sb);
}
void mntput_no_expire(struct vfsmount *mnt)
#ifdef CONFIG_SMP
static inline void __mntput(struct vfsmount *mnt, int longrefs)
{
repeat:
if (atomic_add_unless(&mnt->mnt_count, -1, 1))
if (!longrefs) {
put_again:
br_read_lock(vfsmount_lock);
if (likely(atomic_read(&mnt->mnt_longrefs))) {
mnt_dec_count(mnt);
br_read_unlock(vfsmount_lock);
return;
}
br_read_unlock(vfsmount_lock);
} else {
BUG_ON(!atomic_read(&mnt->mnt_longrefs));
if (atomic_add_unless(&mnt->mnt_longrefs, -1, 1))
return;
}
br_write_lock(vfsmount_lock);
if (!longrefs)
mnt_dec_count(mnt);
else
atomic_dec(&mnt->mnt_longrefs);
if (mnt_get_count(mnt)) {
br_write_unlock(vfsmount_lock);
return;
}
if (unlikely(mnt->mnt_pinned)) {
mnt_add_count(mnt, mnt->mnt_pinned + 1);
mnt->mnt_pinned = 0;
br_write_unlock(vfsmount_lock);
acct_auto_close_mnt(mnt);
goto put_again;
}
br_write_unlock(vfsmount_lock);
mntfree(mnt);
}
#else
static inline void __mntput(struct vfsmount *mnt, int longrefs)
{
put_again:
mnt_dec_count(mnt);
if (likely(mnt_get_count(mnt)))
return;
br_write_lock(vfsmount_lock);
if (!atomic_dec_and_test(&mnt->mnt_count)) {
if (unlikely(mnt->mnt_pinned)) {
mnt_add_count(mnt, mnt->mnt_pinned + 1);
mnt->mnt_pinned = 0;
br_write_unlock(vfsmount_lock);
return;
acct_auto_close_mnt(mnt);
goto put_again;
}
if (likely(!mnt->mnt_pinned)) {
br_write_unlock(vfsmount_lock);
__mntput(mnt);
return;
}
atomic_add(mnt->mnt_pinned + 1, &mnt->mnt_count);
mnt->mnt_pinned = 0;
br_write_unlock(vfsmount_lock);
acct_auto_close_mnt(mnt);
goto repeat;
mntfree(mnt);
}
EXPORT_SYMBOL(mntput_no_expire);
#endif
static void mntput_no_expire(struct vfsmount *mnt)
{
__mntput(mnt, 0);
}
void mntput(struct vfsmount *mnt)
{
if (mnt) {
/* avoid cacheline pingpong, hope gcc doesn't get "smart" */
if (unlikely(mnt->mnt_expiry_mark))
mnt->mnt_expiry_mark = 0;
__mntput(mnt, 0);
}
}
EXPORT_SYMBOL(mntput);
struct vfsmount *mntget(struct vfsmount *mnt)
{
if (mnt)
mnt_inc_count(mnt);
return mnt;
}
EXPORT_SYMBOL(mntget);
void mntput_long(struct vfsmount *mnt)
{
#ifdef CONFIG_SMP
if (mnt) {
/* avoid cacheline pingpong, hope gcc doesn't get "smart" */
if (unlikely(mnt->mnt_expiry_mark))
mnt->mnt_expiry_mark = 0;
__mntput(mnt, 1);
}
#else
mntput(mnt);
#endif
}
EXPORT_SYMBOL(mntput_long);
struct vfsmount *mntget_long(struct vfsmount *mnt)
{
#ifdef CONFIG_SMP
if (mnt)
atomic_inc(&mnt->mnt_longrefs);
return mnt;
#else
return mntget(mnt);
#endif
}
EXPORT_SYMBOL(mntget_long);
void mnt_pin(struct vfsmount *mnt)
{
@ -701,19 +848,17 @@ void mnt_pin(struct vfsmount *mnt)
mnt->mnt_pinned++;
br_write_unlock(vfsmount_lock);
}
EXPORT_SYMBOL(mnt_pin);
void mnt_unpin(struct vfsmount *mnt)
{
br_write_lock(vfsmount_lock);
if (mnt->mnt_pinned) {
atomic_inc(&mnt->mnt_count);
mnt_inc_count(mnt);
mnt->mnt_pinned--;
}
br_write_unlock(vfsmount_lock);
}
EXPORT_SYMBOL(mnt_unpin);
static inline void mangle(struct seq_file *m, const char *s)
@ -1008,12 +1153,13 @@ int may_umount_tree(struct vfsmount *mnt)
int minimum_refs = 0;
struct vfsmount *p;
br_read_lock(vfsmount_lock);
/* write lock needed for mnt_get_count */
br_write_lock(vfsmount_lock);
for (p = mnt; p; p = next_mnt(p, mnt)) {
actual_refs += atomic_read(&p->mnt_count);
actual_refs += mnt_get_count(p);
minimum_refs += 2;
}
br_read_unlock(vfsmount_lock);
br_write_unlock(vfsmount_lock);
if (actual_refs > minimum_refs)
return 0;
@ -1040,10 +1186,10 @@ int may_umount(struct vfsmount *mnt)
{
int ret = 1;
down_read(&namespace_sem);
br_read_lock(vfsmount_lock);
br_write_lock(vfsmount_lock);
if (propagate_mount_busy(mnt, 2))
ret = 0;
br_read_unlock(vfsmount_lock);
br_write_unlock(vfsmount_lock);
up_read(&namespace_sem);
return ret;
}
@ -1070,7 +1216,7 @@ void release_mounts(struct list_head *head)
dput(dentry);
mntput(m);
}
mntput(mnt);
mntput_long(mnt);
}
}
@ -1125,8 +1271,16 @@ static int do_umount(struct vfsmount *mnt, int flags)
flags & (MNT_FORCE | MNT_DETACH))
return -EINVAL;
if (atomic_read(&mnt->mnt_count) != 2)
/*
* probably don't strictly need the lock here if we examined
* all race cases, but it's a slowpath.
*/
br_write_lock(vfsmount_lock);
if (mnt_get_count(mnt) != 2) {
br_write_lock(vfsmount_lock);
return -EBUSY;
}
br_write_unlock(vfsmount_lock);
if (!xchg(&mnt->mnt_expiry_mark, 1))
return -EAGAIN;
@ -1815,7 +1969,7 @@ int do_add_mount(struct vfsmount *newmnt, struct path *path,
unlock:
up_write(&namespace_sem);
mntput(newmnt);
mntput_long(newmnt);
return err;
}
@ -2148,11 +2302,11 @@ static struct mnt_namespace *dup_mnt_ns(struct mnt_namespace *mnt_ns,
if (fs) {
if (p == fs->root.mnt) {
rootmnt = p;
fs->root.mnt = mntget(q);
fs->root.mnt = mntget_long(q);
}
if (p == fs->pwd.mnt) {
pwdmnt = p;
fs->pwd.mnt = mntget(q);
fs->pwd.mnt = mntget_long(q);
}
}
p = next_mnt(p, mnt_ns->root);
@ -2161,9 +2315,9 @@ static struct mnt_namespace *dup_mnt_ns(struct mnt_namespace *mnt_ns,
up_write(&namespace_sem);
if (rootmnt)
mntput(rootmnt);
mntput_long(rootmnt);
if (pwdmnt)
mntput(pwdmnt);
mntput_long(pwdmnt);
return new_ns;
}
@ -2350,6 +2504,7 @@ SYSCALL_DEFINE2(pivot_root, const char __user *, new_root,
touch_mnt_namespace(current->nsproxy->mnt_ns);
br_write_unlock(vfsmount_lock);
chroot_fs_refs(&root, &new);
error = 0;
path_put(&root_parent);
path_put(&parent_path);
@ -2376,6 +2531,7 @@ static void __init init_mount_tree(void)
mnt = do_kern_mount("rootfs", 0, "rootfs", NULL);
if (IS_ERR(mnt))
panic("Can't create rootfs");
ns = create_mnt_ns(mnt);
if (IS_ERR(ns))
panic("Can't allocate initial namespace");

2
fs/pipe.c
View File

@ -1292,7 +1292,7 @@ static int __init init_pipe_fs(void)
static void __exit exit_pipe_fs(void)
{
unregister_filesystem(&pipe_fs_type);
mntput(pipe_mnt);
mntput_long(pipe_mnt);
}
fs_initcall(init_pipe_fs);

4
fs/pnode.c
View File

@ -288,7 +288,7 @@ out:
*/
static inline int do_refcount_check(struct vfsmount *mnt, int count)
{
int mycount = atomic_read(&mnt->mnt_count) - mnt->mnt_ghosts;
int mycount = mnt_get_count(mnt) - mnt->mnt_ghosts;
return (mycount > count);
}
@ -300,7 +300,7 @@ static inline int do_refcount_check(struct vfsmount *mnt, int count)
* Check if any of these mounts that **do not have submounts**
* have more references than 'refcnt'. If so return busy.
*
* vfsmount lock must be held for read or write
* vfsmount lock must be held for write
*/
int propagate_mount_busy(struct vfsmount *mnt, int refcnt)
{

2
fs/super.c
View File

@ -1140,7 +1140,7 @@ static struct vfsmount *fs_set_subtype(struct vfsmount *mnt, const char *fstype)
return mnt;
err:
mntput(mnt);
mntput_long(mnt);
return ERR_PTR(err);
}

53
include/linux/mount.h
View File

@ -13,6 +13,7 @@
#include <linux/list.h>
#include <linux/nodemask.h>
#include <linux/spinlock.h>
#include <linux/seqlock.h>
#include <asm/atomic.h>
struct super_block;
@ -46,12 +47,24 @@ struct mnt_namespace;
#define MNT_INTERNAL 0x4000
struct mnt_pcp {
int mnt_count;
int mnt_writers;
};
struct vfsmount {
struct list_head mnt_hash;
struct vfsmount *mnt_parent; /* fs we are mounted on */
struct dentry *mnt_mountpoint; /* dentry of mountpoint */
struct dentry *mnt_root; /* root of the mounted tree */
struct super_block *mnt_sb; /* pointer to superblock */
#ifdef CONFIG_SMP
struct mnt_pcp __percpu *mnt_pcp;
atomic_t mnt_longrefs;
#else
int mnt_count;
int mnt_writers;
#endif
struct list_head mnt_mounts; /* list of children, anchored here */
struct list_head mnt_child; /* and going through their mnt_child */
int mnt_flags;
@ -70,57 +83,25 @@ struct vfsmount {
struct mnt_namespace *mnt_ns; /* containing namespace */
int mnt_id; /* mount identifier */
int mnt_group_id; /* peer group identifier */
/*
* We put mnt_count & mnt_expiry_mark at the end of struct vfsmount
* to let these frequently modified fields in a separate cache line
* (so that reads of mnt_flags wont ping-pong on SMP machines)
*/
atomic_t mnt_count;
int mnt_expiry_mark; /* true if marked for expiry */
int mnt_pinned;
int mnt_ghosts;
#ifdef CONFIG_SMP
int __percpu *mnt_writers;
#else
int mnt_writers;
#endif
};
static inline int *get_mnt_writers_ptr(struct vfsmount *mnt)
{
#ifdef CONFIG_SMP
return mnt->mnt_writers;
#else
return &mnt->mnt_writers;
#endif
}
static inline struct vfsmount *mntget(struct vfsmount *mnt)
{
if (mnt)
atomic_inc(&mnt->mnt_count);
return mnt;
}
struct file; /* forward dec */
extern int mnt_want_write(struct vfsmount *mnt);
extern int mnt_want_write_file(struct file *file);
extern int mnt_clone_write(struct vfsmount *mnt);
extern void mnt_drop_write(struct vfsmount *mnt);
extern void mntput_no_expire(struct vfsmount *mnt);
extern void mntput(struct vfsmount *mnt);
extern struct vfsmount *mntget(struct vfsmount *mnt);
extern void mntput_long(struct vfsmount *mnt);
extern struct vfsmount *mntget_long(struct vfsmount *mnt);
extern void mnt_pin(struct vfsmount *mnt);
extern void mnt_unpin(struct vfsmount *mnt);
extern int __mnt_is_readonly(struct vfsmount *mnt);
static inline void mntput(struct vfsmount *mnt)
{
if (mnt) {
mnt->mnt_expiry_mark = 0;
mntput_no_expire(mnt);
}
}
extern struct vfsmount *do_kern_mount(const char *fstype, int flags,
const char *name, void *data);

2
include/linux/path.h
View File

@ -10,7 +10,9 @@ struct path {
};
extern void path_get(struct path *);
extern void path_get_long(struct path *);
extern void path_put(struct path *);
extern void path_put_long(struct path *);
static inline int path_equal(const struct path *path1, const struct path *path2)
{

19
net/socket.c
View File

@ -2390,6 +2390,8 @@ EXPORT_SYMBOL(sock_unregister);
static int __init sock_init(void)
{
int err;
/*
* Initialize sock SLAB cache.
*/
@ -2406,8 +2408,15 @@ static int __init sock_init(void)
*/
init_inodecache();
register_filesystem(&sock_fs_type);
err = register_filesystem(&sock_fs_type);
if (err)
goto out_fs;
sock_mnt = kern_mount(&sock_fs_type);
if (IS_ERR(sock_mnt)) {
err = PTR_ERR(sock_mnt);
goto out_mount;
}
/* The real protocol initialization is performed in later initcalls.
*/
@ -2420,7 +2429,13 @@ static int __init sock_init(void)
skb_timestamping_init();
#endif
return 0;
out:
return err;
out_mount:
unregister_filesystem(&sock_fs_type);
out_fs:
goto out;
}
core_initcall(sock_init); /* early initcall */