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vfs: spread struct mount - work with counters 

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
This commit is contained in:
Al Viro 2011-11-24 22:37:54 -05:00
parent a73324da7a
commit 83adc75322
3 changed files with 66 additions and 62 deletions
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124
fs/namespace.c
View File

@ -141,13 +141,13 @@ void mnt_release_group_id(struct mount *mnt)
/*
* vfsmount lock must be held for read
*/
static inline void mnt_add_count(struct vfsmount *mnt, int n)
static inline void mnt_add_count(struct mount *mnt, int n)
{
#ifdef CONFIG_SMP
this_cpu_add(mnt->mnt_pcp->mnt_count, n);
this_cpu_add(mnt->mnt.mnt_pcp->mnt_count, n);
#else
preempt_disable();
mnt->mnt_count += n;
mnt->mnt.mnt_count += n;
preempt_enable();
#endif
}
@ -155,19 +155,19 @@ static inline void mnt_add_count(struct vfsmount *mnt, int n)
/*
* vfsmount lock must be held for write
*/
unsigned int mnt_get_count(struct vfsmount *mnt)
unsigned int mnt_get_count(struct mount *mnt)
{
#ifdef CONFIG_SMP
unsigned int count = 0;
int cpu;
for_each_possible_cpu(cpu) {
count += per_cpu_ptr(mnt->mnt_pcp, cpu)->mnt_count;
count += per_cpu_ptr(mnt->mnt.mnt_pcp, cpu)->mnt_count;
}
return count;
#else
return mnt->mnt_count;
return mnt->mnt.mnt_count;
#endif
}
@ -253,32 +253,32 @@ int __mnt_is_readonly(struct vfsmount *mnt)
}
EXPORT_SYMBOL_GPL(__mnt_is_readonly);
static inline void mnt_inc_writers(struct vfsmount *mnt)
static inline void mnt_inc_writers(struct mount *mnt)
{
#ifdef CONFIG_SMP
this_cpu_inc(mnt->mnt_pcp->mnt_writers);
this_cpu_inc(mnt->mnt.mnt_pcp->mnt_writers);
#else
mnt->mnt_writers++;
mnt->mnt.mnt_writers++;
#endif
}
static inline void mnt_dec_writers(struct vfsmount *mnt)
static inline void mnt_dec_writers(struct mount *mnt)
{
#ifdef CONFIG_SMP
this_cpu_dec(mnt->mnt_pcp->mnt_writers);
this_cpu_dec(mnt->mnt.mnt_pcp->mnt_writers);
#else
mnt->mnt_writers--;
mnt->mnt.mnt_writers--;
#endif
}
static unsigned int mnt_get_writers(struct vfsmount *mnt)
static unsigned int mnt_get_writers(struct mount *mnt)
{
#ifdef CONFIG_SMP
unsigned int count = 0;
int cpu;
for_each_possible_cpu(cpu) {
count += per_cpu_ptr(mnt->mnt_pcp, cpu)->mnt_writers;
count += per_cpu_ptr(mnt->mnt.mnt_pcp, cpu)->mnt_writers;
}
return count;
@ -297,7 +297,7 @@ static unsigned int mnt_get_writers(struct vfsmount *mnt)
*/
/**
* mnt_want_write - get write access to a mount
* @mnt: the mount on which to take a write
* @m: the mount on which to take a write
*
* This tells the low-level filesystem that a write is
* about to be performed to it, and makes sure that
@ -305,8 +305,9 @@ static unsigned int mnt_get_writers(struct vfsmount *mnt)
* the write operation is finished, mnt_drop_write()
* must be called. This is effectively a refcount.
*/
int mnt_want_write(struct vfsmount *mnt)
int mnt_want_write(struct vfsmount *m)
{
struct mount *mnt = real_mount(m);
int ret = 0;
preempt_disable();
@ -317,7 +318,7 @@ int mnt_want_write(struct vfsmount *mnt)
* incremented count after it has set MNT_WRITE_HOLD.
*/
smp_mb();
while (mnt->mnt_flags & MNT_WRITE_HOLD)
while (mnt->mnt.mnt_flags & MNT_WRITE_HOLD)
cpu_relax();
/*
* After the slowpath clears MNT_WRITE_HOLD, mnt_is_readonly will
@ -325,7 +326,7 @@ int mnt_want_write(struct vfsmount *mnt)
* MNT_WRITE_HOLD is cleared.
*/
smp_rmb();
if (__mnt_is_readonly(mnt)) {
if (__mnt_is_readonly(m)) {
mnt_dec_writers(mnt);
ret = -EROFS;
goto out;
@ -354,7 +355,7 @@ int mnt_clone_write(struct vfsmount *mnt)
if (__mnt_is_readonly(mnt))
return -EROFS;
preempt_disable();
mnt_inc_writers(mnt);
mnt_inc_writers(real_mount(mnt));
preempt_enable();
return 0;
}
@ -388,7 +389,7 @@ EXPORT_SYMBOL_GPL(mnt_want_write_file);
void mnt_drop_write(struct vfsmount *mnt)
{
preempt_disable();
mnt_dec_writers(mnt);
mnt_dec_writers(real_mount(mnt));
preempt_enable();
}
EXPORT_SYMBOL_GPL(mnt_drop_write);
@ -399,12 +400,12 @@ void mnt_drop_write_file(struct file *file)
}
EXPORT_SYMBOL(mnt_drop_write_file);
static int mnt_make_readonly(struct vfsmount *mnt)
static int mnt_make_readonly(struct mount *mnt)
{
int ret = 0;
br_write_lock(vfsmount_lock);
mnt->mnt_flags |= MNT_WRITE_HOLD;
mnt->mnt.mnt_flags |= MNT_WRITE_HOLD;
/*
* After storing MNT_WRITE_HOLD, we'll read the counters. This store
* should be visible before we do.
@ -430,21 +431,21 @@ static int mnt_make_readonly(struct vfsmount *mnt)
if (mnt_get_writers(mnt) > 0)
ret = -EBUSY;
else
mnt->mnt_flags |= MNT_READONLY;
mnt->mnt.mnt_flags |= MNT_READONLY;
/*
* MNT_READONLY must become visible before ~MNT_WRITE_HOLD, so writers
* that become unheld will see MNT_READONLY.
*/
smp_wmb();
mnt->mnt_flags &= ~MNT_WRITE_HOLD;
mnt->mnt.mnt_flags &= ~MNT_WRITE_HOLD;
br_write_unlock(vfsmount_lock);
return ret;
}
static void __mnt_unmake_readonly(struct vfsmount *mnt)
static void __mnt_unmake_readonly(struct mount *mnt)
{
br_write_lock(vfsmount_lock);
mnt->mnt_flags &= ~MNT_READONLY;
mnt->mnt.mnt_flags &= ~MNT_READONLY;
br_write_unlock(vfsmount_lock);
}
@ -590,18 +591,18 @@ static void attach_mnt(struct mount *mnt, struct path *path)
list_add_tail(&mnt->mnt.mnt_child, &path->mnt->mnt_mounts);
}
static inline void __mnt_make_longterm(struct vfsmount *mnt)
static inline void __mnt_make_longterm(struct mount *mnt)
{
#ifdef CONFIG_SMP
atomic_inc(&mnt->mnt_longterm);
atomic_inc(&mnt->mnt.mnt_longterm);
#endif
}
/* needs vfsmount lock for write */
static inline void __mnt_make_shortterm(struct vfsmount *mnt)
static inline void __mnt_make_shortterm(struct mount *mnt)
{
#ifdef CONFIG_SMP
atomic_dec(&mnt->mnt_longterm);
atomic_dec(&mnt->mnt.mnt_longterm);
#endif
}
@ -611,15 +612,15 @@ static inline void __mnt_make_shortterm(struct vfsmount *mnt)
static void commit_tree(struct mount *mnt)
{
struct mount *parent = mnt->mnt_parent;
struct vfsmount *m;
struct mount *m;
LIST_HEAD(head);
struct mnt_namespace *n = parent->mnt.mnt_ns;
BUG_ON(parent == mnt);
list_add_tail(&head, &mnt->mnt.mnt_list);
list_for_each_entry(m, &head, mnt_list) {
m->mnt_ns = n;
list_for_each_entry(m, &head, mnt.mnt_list) {
m->mnt.mnt_ns = n;
__mnt_make_longterm(m);
}
@ -740,9 +741,10 @@ static struct mount *clone_mnt(struct mount *old, struct dentry *root,
return NULL;
}
static inline void mntfree(struct vfsmount *mnt)
static inline void mntfree(struct mount *mnt)
{
struct super_block *sb = mnt->mnt_sb;
struct vfsmount *m = &mnt->mnt;
struct super_block *sb = m->mnt_sb;
/*
* This probably indicates that somebody messed
@ -755,18 +757,19 @@ static inline void mntfree(struct vfsmount *mnt)
* so mnt_get_writers() below is safe.
*/
WARN_ON(mnt_get_writers(mnt));
fsnotify_vfsmount_delete(mnt);
dput(mnt->mnt_root);
free_vfsmnt(real_mount(mnt));
fsnotify_vfsmount_delete(m);
dput(m->mnt_root);
free_vfsmnt(mnt);
deactivate_super(sb);
}
static void mntput_no_expire(struct vfsmount *mnt)
static void mntput_no_expire(struct vfsmount *m)
{
struct mount *mnt = real_mount(m);
put_again:
#ifdef CONFIG_SMP
br_read_lock(vfsmount_lock);
if (likely(atomic_read(&mnt->mnt_longterm))) {
if (likely(atomic_read(&mnt->mnt.mnt_longterm))) {
mnt_add_count(mnt, -1);
br_read_unlock(vfsmount_lock);
return;
@ -785,11 +788,11 @@ put_again:
return;
br_write_lock(vfsmount_lock);
#endif
if (unlikely(mnt->mnt_pinned)) {
mnt_add_count(mnt, mnt->mnt_pinned + 1);
mnt->mnt_pinned = 0;
if (unlikely(mnt->mnt.mnt_pinned)) {
mnt_add_count(mnt, mnt->mnt.mnt_pinned + 1);
mnt->mnt.mnt_pinned = 0;
br_write_unlock(vfsmount_lock);
acct_auto_close_mnt(mnt);
acct_auto_close_mnt(m);
goto put_again;
}
br_write_unlock(vfsmount_lock);
@ -810,7 +813,7 @@ EXPORT_SYMBOL(mntput);
struct vfsmount *mntget(struct vfsmount *mnt)
{
if (mnt)
mnt_add_count(mnt, 1);
mnt_add_count(real_mount(mnt), 1);
return mnt;
}
EXPORT_SYMBOL(mntget);
@ -827,7 +830,7 @@ void mnt_unpin(struct vfsmount *mnt)
{
br_write_lock(vfsmount_lock);
if (mnt->mnt_pinned) {
mnt_add_count(mnt, 1);
mnt_add_count(real_mount(mnt), 1);
mnt->mnt_pinned--;
}
br_write_unlock(vfsmount_lock);
@ -1150,7 +1153,7 @@ int may_umount_tree(struct vfsmount *mnt)
/* write lock needed for mnt_get_count */
br_write_lock(vfsmount_lock);
for (p = real_mount(mnt); p; p = next_mnt(p, mnt)) {
actual_refs += mnt_get_count(&p->mnt);
actual_refs += mnt_get_count(p);
minimum_refs += 2;
}
br_write_unlock(vfsmount_lock);
@ -1234,7 +1237,7 @@ void umount_tree(struct mount *mnt, int propagate, struct list_head *kill)
list_del_init(&p->mnt.mnt_list);
__touch_mnt_namespace(p->mnt.mnt_ns);
p->mnt.mnt_ns = NULL;
__mnt_make_shortterm(&p->mnt);
__mnt_make_shortterm(p);
list_del_init(&p->mnt.mnt_child);
if (mnt_has_parent(p)) {
p->mnt_parent->mnt.mnt_ghosts++;
@ -1273,7 +1276,7 @@ static int do_umount(struct mount *mnt, int flags)
* all race cases, but it's a slowpath.
*/
br_write_lock(vfsmount_lock);
if (mnt_get_count(&mnt->mnt) != 2) {
if (mnt_get_count(mnt) != 2) {
br_write_unlock(vfsmount_lock);
return -EBUSY;
}
@ -1798,9 +1801,9 @@ static int change_mount_flags(struct vfsmount *mnt, int ms_flags)
return 0;
if (readonly_request)
error = mnt_make_readonly(mnt);
error = mnt_make_readonly(real_mount(mnt));
else
__mnt_unmake_readonly(mnt);
__mnt_unmake_readonly(real_mount(mnt));
return error;
}
@ -2034,7 +2037,7 @@ int finish_automount(struct vfsmount *m, struct path *path)
/* The new mount record should have at least 2 refs to prevent it being
* expired before we get a chance to add it
*/
BUG_ON(mnt_get_count(m) < 2);
BUG_ON(mnt_get_count(real_mount(m)) < 2);
if (m->mnt_sb == path->mnt->mnt_sb &&
m->mnt_root == path->dentry) {
@ -2365,16 +2368,17 @@ static struct mnt_namespace *alloc_mnt_ns(void)
void mnt_make_longterm(struct vfsmount *mnt)
{
__mnt_make_longterm(mnt);
__mnt_make_longterm(real_mount(mnt));
}
void mnt_make_shortterm(struct vfsmount *mnt)
void mnt_make_shortterm(struct vfsmount *m)
{
#ifdef CONFIG_SMP
if (atomic_add_unless(&mnt->mnt_longterm, -1, 1))
struct mount *mnt = real_mount(m);
if (atomic_add_unless(&mnt->mnt.mnt_longterm, -1, 1))
return;
br_write_lock(vfsmount_lock);
atomic_dec(&mnt->mnt_longterm);
atomic_dec(&mnt->mnt.mnt_longterm);
br_write_unlock(vfsmount_lock);
#endif
}
@ -2418,17 +2422,17 @@ static struct mnt_namespace *dup_mnt_ns(struct mnt_namespace *mnt_ns,
q = new;
while (p) {
q->mnt.mnt_ns = new_ns;
__mnt_make_longterm(&q->mnt);
__mnt_make_longterm(q);
if (fs) {
if (&p->mnt == fs->root.mnt) {
fs->root.mnt = mntget(&q->mnt);
__mnt_make_longterm(&q->mnt);
__mnt_make_longterm(q);
mnt_make_shortterm(&p->mnt);
rootmnt = &p->mnt;
}
if (&p->mnt == fs->pwd.mnt) {
fs->pwd.mnt = mntget(&q->mnt);
__mnt_make_longterm(&q->mnt);
__mnt_make_longterm(q);
mnt_make_shortterm(&p->mnt);
pwdmnt = &p->mnt;
}
@ -2474,7 +2478,7 @@ static struct mnt_namespace *create_mnt_ns(struct vfsmount *mnt)
new_ns = alloc_mnt_ns();
if (!IS_ERR(new_ns)) {
mnt->mnt_ns = new_ns;
__mnt_make_longterm(mnt);
__mnt_make_longterm(real_mount(mnt));
new_ns->root = mnt;
list_add(&new_ns->list, &new_ns->root->mnt_list);
} else {

2
fs/pnode.c
View File

@ -274,7 +274,7 @@ out:
*/
static inline int do_refcount_check(struct mount *mnt, int count)
{
int mycount = mnt_get_count(&mnt->mnt) - mnt->mnt.mnt_ghosts;
int mycount = mnt_get_count(mnt) - mnt->mnt.mnt_ghosts;
return (mycount > count);
}

2
fs/pnode.h
View File

@ -36,7 +36,7 @@ int propagate_umount(struct list_head *);
int propagate_mount_busy(struct mount *, int);
void mnt_release_group_id(struct mount *);
int get_dominating_id(struct vfsmount *mnt, const struct path *root);
unsigned int mnt_get_count(struct vfsmount *mnt);
unsigned int mnt_get_count(struct mount *mnt);
void mnt_set_mountpoint(struct vfsmount *, struct dentry *,
struct mount *);
void release_mounts(struct list_head *);