Commit 3e93cd67 authored by Al Viro's avatar Al Viro

Take fs_struct handling to new file (fs/fs_struct.c)

Pure code move; two new helper functions for nfsd and daemonize
(unshare_fs_struct() and daemonize_fs_struct() resp.; for now -
the same code as used to be in callers).  unshare_fs_struct()
exported (for nfsd, as copy_fs_struct()/exit_fs() used to be),
copy_fs_struct() and exit_fs() don't need exports anymore.
Signed-off-by: 's avatarAl Viro <viro@zeniv.linux.org.uk>
parent f8ef3ed2
......@@ -11,7 +11,7 @@ obj-y := open.o read_write.o file_table.o super.o \
attr.o bad_inode.o file.o filesystems.o namespace.o \
seq_file.o xattr.o libfs.o fs-writeback.o \
pnode.o drop_caches.o splice.o sync.o utimes.o \
stack.o
stack.o fs_struct.o
ifeq ($(CONFIG_BLOCK),y)
obj-y += buffer.o bio.o block_dev.o direct-io.o mpage.o ioprio.o
......
#include <linux/module.h>
#include <linux/sched.h>
#include <linux/fs.h>
#include <linux/path.h>
#include <linux/slab.h>
/*
* Replace the fs->{rootmnt,root} with {mnt,dentry}. Put the old values.
* It can block.
*/
void set_fs_root(struct fs_struct *fs, struct path *path)
{
struct path old_root;
write_lock(&fs->lock);
old_root = fs->root;
fs->root = *path;
path_get(path);
write_unlock(&fs->lock);
if (old_root.dentry)
path_put(&old_root);
}
/*
* Replace the fs->{pwdmnt,pwd} with {mnt,dentry}. Put the old values.
* It can block.
*/
void set_fs_pwd(struct fs_struct *fs, struct path *path)
{
struct path old_pwd;
write_lock(&fs->lock);
old_pwd = fs->pwd;
fs->pwd = *path;
path_get(path);
write_unlock(&fs->lock);
if (old_pwd.dentry)
path_put(&old_pwd);
}
void chroot_fs_refs(struct path *old_root, struct path *new_root)
{
struct task_struct *g, *p;
struct fs_struct *fs;
int count = 0;
read_lock(&tasklist_lock);
do_each_thread(g, p) {
task_lock(p);
fs = p->fs;
if (fs) {
write_lock(&fs->lock);
if (fs->root.dentry == old_root->dentry
&& fs->root.mnt == old_root->mnt) {
path_get(new_root);
fs->root = *new_root;
count++;
}
if (fs->pwd.dentry == old_root->dentry
&& fs->pwd.mnt == old_root->mnt) {
path_get(new_root);
fs->pwd = *new_root;
count++;
}
write_unlock(&fs->lock);
}
task_unlock(p);
} while_each_thread(g, p);
read_unlock(&tasklist_lock);
while (count--)
path_put(old_root);
}
void put_fs_struct(struct fs_struct *fs)
{
/* No need to hold fs->lock if we are killing it */
if (atomic_dec_and_test(&fs->count)) {
path_put(&fs->root);
path_put(&fs->pwd);
kmem_cache_free(fs_cachep, fs);
}
}
void exit_fs(struct task_struct *tsk)
{
struct fs_struct * fs = tsk->fs;
if (fs) {
task_lock(tsk);
tsk->fs = NULL;
task_unlock(tsk);
put_fs_struct(fs);
}
}
struct fs_struct *copy_fs_struct(struct fs_struct *old)
{
struct fs_struct *fs = kmem_cache_alloc(fs_cachep, GFP_KERNEL);
/* We don't need to lock fs - think why ;-) */
if (fs) {
atomic_set(&fs->count, 1);
rwlock_init(&fs->lock);
fs->umask = old->umask;
read_lock(&old->lock);
fs->root = old->root;
path_get(&old->root);
fs->pwd = old->pwd;
path_get(&old->pwd);
read_unlock(&old->lock);
}
return fs;
}
int unshare_fs_struct(void)
{
struct fs_struct *fsp = copy_fs_struct(current->fs);
if (!fsp)
return -ENOMEM;
exit_fs(current);
current->fs = fsp;
return 0;
}
EXPORT_SYMBOL_GPL(unshare_fs_struct);
/* to be mentioned only in INIT_TASK */
struct fs_struct init_fs = {
.count = ATOMIC_INIT(1),
.lock = __RW_LOCK_UNLOCKED(init_fs.lock),
.umask = 0022,
};
void daemonize_fs_struct(void)
{
struct fs_struct *fs;
exit_fs(current); /* current->fs->count--; */
fs = &init_fs;
current->fs = fs;
atomic_inc(&fs->count);
}
......@@ -11,6 +11,7 @@
struct super_block;
struct linux_binprm;
struct path;
/*
* block_dev.c
......@@ -60,3 +61,8 @@ extern void umount_tree(struct vfsmount *, int, struct list_head *);
extern struct vfsmount *copy_tree(struct vfsmount *, struct dentry *, int);
extern void __init mnt_init(void);
/*
* fs_struct.c
*/
extern void chroot_fs_refs(struct path *, struct path *);
......@@ -2897,10 +2897,3 @@ EXPORT_SYMBOL(vfs_symlink);
EXPORT_SYMBOL(vfs_unlink);
EXPORT_SYMBOL(dentry_unhash);
EXPORT_SYMBOL(generic_readlink);
/* to be mentioned only in INIT_TASK */
struct fs_struct init_fs = {
.count = ATOMIC_INIT(1),
.lock = __RW_LOCK_UNLOCKED(init_fs.lock),
.umask = 0022,
};
......@@ -2092,74 +2092,6 @@ SYSCALL_DEFINE5(mount, char __user *, dev_name, char __user *, dir_name,
return retval;
}
/*
* Replace the fs->{rootmnt,root} with {mnt,dentry}. Put the old values.
* It can block. Requires the big lock held.
*/
void set_fs_root(struct fs_struct *fs, struct path *path)
{
struct path old_root;
write_lock(&fs->lock);
old_root = fs->root;
fs->root = *path;
path_get(path);
write_unlock(&fs->lock);
if (old_root.dentry)
path_put(&old_root);
}
/*
* Replace the fs->{pwdmnt,pwd} with {mnt,dentry}. Put the old values.
* It can block. Requires the big lock held.
*/
void set_fs_pwd(struct fs_struct *fs, struct path *path)
{
struct path old_pwd;
write_lock(&fs->lock);
old_pwd = fs->pwd;
fs->pwd = *path;
path_get(path);
write_unlock(&fs->lock);
if (old_pwd.dentry)
path_put(&old_pwd);
}
static void chroot_fs_refs(struct path *old_root, struct path *new_root)
{
struct task_struct *g, *p;
struct fs_struct *fs;
int count = 0;
read_lock(&tasklist_lock);
do_each_thread(g, p) {
task_lock(p);
fs = p->fs;
if (fs) {
write_lock(&fs->lock);
if (fs->root.dentry == old_root->dentry
&& fs->root.mnt == old_root->mnt) {
path_get(new_root);
fs->root = *new_root;
count++;
}
if (fs->pwd.dentry == old_root->dentry
&& fs->pwd.mnt == old_root->mnt) {
path_get(new_root);
fs->pwd = *new_root;
count++;
}
write_unlock(&fs->lock);
}
task_unlock(p);
} while_each_thread(g, p);
read_unlock(&tasklist_lock);
while (count--)
path_put(old_root);
}
/*
* pivot_root Semantics:
* Moves the root file system of the current process to the directory put_old,
......
......@@ -404,7 +404,6 @@ static int
nfsd(void *vrqstp)
{
struct svc_rqst *rqstp = (struct svc_rqst *) vrqstp;
struct fs_struct *fsp;
int err, preverr = 0;
/* Lock module and set up kernel thread */
......@@ -413,13 +412,11 @@ nfsd(void *vrqstp)
/* At this point, the thread shares current->fs
* with the init process. We need to create files with a
* umask of 0 instead of init's umask. */
fsp = copy_fs_struct(current->fs);
if (!fsp) {
if (unshare_fs_struct() < 0) {
printk("Unable to start nfsd thread: out of memory\n");
goto out;
}
exit_fs(current);
current->fs = fsp;
current->fs->umask = 0;
/*
......
......@@ -20,5 +20,7 @@ extern void set_fs_root(struct fs_struct *, struct path *);
extern void set_fs_pwd(struct fs_struct *, struct path *);
extern struct fs_struct *copy_fs_struct(struct fs_struct *);
extern void put_fs_struct(struct fs_struct *);
extern void daemonize_fs_struct(void);
extern int unshare_fs_struct(void);
#endif /* _LINUX_FS_STRUCT_H */
......@@ -429,7 +429,6 @@ EXPORT_SYMBOL(disallow_signal);
void daemonize(const char *name, ...)
{
va_list args;
struct fs_struct *fs;
sigset_t blocked;
va_start(args, name);
......@@ -462,11 +461,7 @@ void daemonize(const char *name, ...)
/* Become as one with the init task */
exit_fs(current); /* current->fs->count--; */
fs = init_task.fs;
current->fs = fs;
atomic_inc(&fs->count);
daemonize_fs_struct();
exit_files(current);
current->files = init_task.files;
atomic_inc(&current->files->count);
......@@ -565,30 +560,6 @@ void exit_files(struct task_struct *tsk)
}
}
void put_fs_struct(struct fs_struct *fs)
{
/* No need to hold fs->lock if we are killing it */
if (atomic_dec_and_test(&fs->count)) {
path_put(&fs->root);
path_put(&fs->pwd);
kmem_cache_free(fs_cachep, fs);
}
}
void exit_fs(struct task_struct *tsk)
{
struct fs_struct * fs = tsk->fs;
if (fs) {
task_lock(tsk);
tsk->fs = NULL;
task_unlock(tsk);
put_fs_struct(fs);
}
}
EXPORT_SYMBOL_GPL(exit_fs);
#ifdef CONFIG_MM_OWNER
/*
* Task p is exiting and it owned mm, lets find a new owner for it
......
......@@ -681,38 +681,13 @@ static int copy_mm(unsigned long clone_flags, struct task_struct * tsk)
return retval;
}
static struct fs_struct *__copy_fs_struct(struct fs_struct *old)
{
struct fs_struct *fs = kmem_cache_alloc(fs_cachep, GFP_KERNEL);
/* We don't need to lock fs - think why ;-) */
if (fs) {
atomic_set(&fs->count, 1);
rwlock_init(&fs->lock);
fs->umask = old->umask;
read_lock(&old->lock);
fs->root = old->root;
path_get(&old->root);
fs->pwd = old->pwd;
path_get(&old->pwd);
read_unlock(&old->lock);
}
return fs;
}
struct fs_struct *copy_fs_struct(struct fs_struct *old)
{
return __copy_fs_struct(old);
}
EXPORT_SYMBOL_GPL(copy_fs_struct);
static int copy_fs(unsigned long clone_flags, struct task_struct *tsk)
{
if (clone_flags & CLONE_FS) {
atomic_inc(&current->fs->count);
return 0;
}
tsk->fs = __copy_fs_struct(current->fs);
tsk->fs = copy_fs_struct(current->fs);
if (!tsk->fs)
return -ENOMEM;
return 0;
......@@ -1545,7 +1520,7 @@ static int unshare_fs(unsigned long unshare_flags, struct fs_struct **new_fsp)
if ((unshare_flags & CLONE_FS) &&
(fs && atomic_read(&fs->count) > 1)) {
*new_fsp = __copy_fs_struct(current->fs);
*new_fsp = copy_fs_struct(current->fs);
if (!*new_fsp)
return -ENOMEM;
}
......
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