#include <linux/string.h>
#include <linux/slab.h>
#include <linux/file.h>
+#include <linux/fdtable.h>
#include <linux/init.h>
#include <linux/module.h>
-#include <linux/smp_lock.h>
#include <linux/fs.h>
#include <linux/security.h>
#include <linux/eventpoll.h>
+#include <linux/rcupdate.h>
#include <linux/mount.h>
+#include <linux/capability.h>
#include <linux/cdev.h>
#include <linux/fsnotify.h>
+#include <linux/sysctl.h>
+#include <linux/percpu_counter.h>
+#include <linux/ima.h>
+
+#include <asm/atomic.h>
+
+#include "internal.h"
/* sysctl tunables... */
struct files_stat_struct files_stat = {
.max_files = NR_FILE
};
-EXPORT_SYMBOL(files_stat); /* Needed by unix.o */
-
/* public. Not pretty! */
- __cacheline_aligned_in_smp DEFINE_SPINLOCK(files_lock);
+__cacheline_aligned_in_smp DEFINE_SPINLOCK(files_lock);
+
+/* SLAB cache for file structures */
+static struct kmem_cache *filp_cachep __read_mostly;
+
+static struct percpu_counter nr_files __cacheline_aligned_in_smp;
+
+static inline void file_free_rcu(struct rcu_head *head)
+{
+ struct file *f = container_of(head, struct file, f_u.fu_rcuhead);
+
+ put_cred(f->f_cred);
+ kmem_cache_free(filp_cachep, f);
+}
-static DEFINE_SPINLOCK(filp_count_lock);
+static inline void file_free(struct file *f)
+{
+ percpu_counter_dec(&nr_files);
+ file_check_state(f);
+ call_rcu(&f->f_u.fu_rcuhead, file_free_rcu);
+}
-/* slab constructors and destructors are called from arbitrary
- * context and must be fully threaded - use a local spinlock
- * to protect files_stat.nr_files
+/*
+ * Return the total number of open files in the system
*/
-void filp_ctor(void * objp, struct kmem_cache_s *cachep, unsigned long cflags)
+static int get_nr_files(void)
{
- if ((cflags & (SLAB_CTOR_VERIFY|SLAB_CTOR_CONSTRUCTOR)) ==
- SLAB_CTOR_CONSTRUCTOR) {
- unsigned long flags;
- spin_lock_irqsave(&filp_count_lock, flags);
- files_stat.nr_files++;
- spin_unlock_irqrestore(&filp_count_lock, flags);
- }
+ return percpu_counter_read_positive(&nr_files);
}
-void filp_dtor(void * objp, struct kmem_cache_s *cachep, unsigned long dflags)
+/*
+ * Return the maximum number of open files in the system
+ */
+int get_max_files(void)
{
- unsigned long flags;
- spin_lock_irqsave(&filp_count_lock, flags);
- files_stat.nr_files--;
- spin_unlock_irqrestore(&filp_count_lock, flags);
+ return files_stat.max_files;
}
+EXPORT_SYMBOL_GPL(get_max_files);
-static inline void file_free(struct file *f)
+/*
+ * Handle nr_files sysctl
+ */
+#if defined(CONFIG_SYSCTL) && defined(CONFIG_PROC_FS)
+int proc_nr_files(ctl_table *table, int write,
+ void __user *buffer, size_t *lenp, loff_t *ppos)
{
- kmem_cache_free(filp_cachep, f);
+ files_stat.nr_files = get_nr_files();
+ return proc_dointvec(table, write, buffer, lenp, ppos);
+}
+#else
+int proc_nr_files(ctl_table *table, int write,
+ void __user *buffer, size_t *lenp, loff_t *ppos)
+{
+ return -ENOSYS;
}
+#endif
/* Find an unused file structure and return a pointer to it.
* Returns NULL, if there are no more free file structures or
* we run out of memory.
+ *
+ * Be very careful using this. You are responsible for
+ * getting write access to any mount that you might assign
+ * to this filp, if it is opened for write. If this is not
+ * done, you will imbalance int the mount's writer count
+ * and a warning at __fput() time.
*/
struct file *get_empty_filp(void)
{
+ const struct cred *cred = current_cred();
static int old_max;
struct file * f;
/*
* Privileged users can go above max_files
*/
- if (files_stat.nr_files >= files_stat.max_files &&
- !capable(CAP_SYS_ADMIN))
- goto over;
+ if (get_nr_files() >= files_stat.max_files && !capable(CAP_SYS_ADMIN)) {
+ /*
+ * percpu_counters are inaccurate. Do an expensive check before
+ * we go and fail.
+ */
+ if (percpu_counter_sum_positive(&nr_files) >= files_stat.max_files)
+ goto over;
+ }
- f = kmem_cache_alloc(filp_cachep, GFP_KERNEL);
+ f = kmem_cache_zalloc(filp_cachep, GFP_KERNEL);
if (f == NULL)
goto fail;
- memset(f, 0, sizeof(*f));
+ percpu_counter_inc(&nr_files);
if (security_file_alloc(f))
goto fail_sec;
- eventpoll_init_file(f);
- atomic_set(&f->f_count, 1);
- f->f_uid = current->fsuid;
- f->f_gid = current->fsgid;
+ INIT_LIST_HEAD(&f->f_u.fu_list);
+ atomic_long_set(&f->f_count, 1);
rwlock_init(&f->f_owner.lock);
+ f->f_cred = get_cred(cred);
+ spin_lock_init(&f->f_lock);
+ eventpoll_init_file(f);
/* f->f_version: 0 */
- INIT_LIST_HEAD(&f->f_list);
- f->f_maxcount = INT_MAX;
return f;
over:
/* Ran out of filps - report that */
- if (files_stat.nr_files > old_max) {
+ if (get_nr_files() > old_max) {
printk(KERN_INFO "VFS: file-max limit %d reached\n",
- files_stat.max_files);
- old_max = files_stat.nr_files;
+ get_max_files());
+ old_max = get_nr_files();
}
goto fail;
return NULL;
}
-EXPORT_SYMBOL(get_empty_filp);
+/**
+ * alloc_file - allocate and initialize a 'struct file'
+ * @mnt: the vfsmount on which the file will reside
+ * @dentry: the dentry representing the new file
+ * @mode: the mode with which the new file will be opened
+ * @fop: the 'struct file_operations' for the new file
+ *
+ * Use this instead of get_empty_filp() to get a new
+ * 'struct file'. Do so because of the same initialization
+ * pitfalls reasons listed for init_file(). This is a
+ * preferred interface to using init_file().
+ *
+ * If all the callers of init_file() are eliminated, its
+ * code should be moved into this function.
+ */
+struct file *alloc_file(struct path *path, fmode_t mode,
+ const struct file_operations *fop)
+{
+ struct file *file;
-void fastcall fput(struct file *file)
+ file = get_empty_filp();
+ if (!file)
+ return NULL;
+
+ file->f_path = *path;
+ file->f_mapping = path->dentry->d_inode->i_mapping;
+ file->f_mode = mode;
+ file->f_op = fop;
+
+ /*
+ * These mounts don't really matter in practice
+ * for r/o bind mounts. They aren't userspace-
+ * visible. We do this for consistency, and so
+ * that we can do debugging checks at __fput()
+ */
+ if ((mode & FMODE_WRITE) && !special_file(path->dentry->d_inode->i_mode)) {
+ file_take_write(file);
+ WARN_ON(mnt_clone_write(path->mnt));
+ }
+ ima_counts_get(file);
+ return file;
+}
+EXPORT_SYMBOL(alloc_file);
+
+void fput(struct file *file)
{
- if (atomic_dec_and_test(&file->f_count))
+ if (atomic_long_dec_and_test(&file->f_count))
__fput(file);
}
EXPORT_SYMBOL(fput);
+/**
+ * drop_file_write_access - give up ability to write to a file
+ * @file: the file to which we will stop writing
+ *
+ * This is a central place which will give up the ability
+ * to write to @file, along with access to write through
+ * its vfsmount.
+ */
+void drop_file_write_access(struct file *file)
+{
+ struct vfsmount *mnt = file->f_path.mnt;
+ struct dentry *dentry = file->f_path.dentry;
+ struct inode *inode = dentry->d_inode;
+
+ put_write_access(inode);
+
+ if (special_file(inode->i_mode))
+ return;
+ if (file_check_writeable(file) != 0)
+ return;
+ mnt_drop_write(mnt);
+ file_release_write(file);
+}
+EXPORT_SYMBOL_GPL(drop_file_write_access);
+
/* __fput is called from task context when aio completion releases the last
* last use of a struct file *. Do not use otherwise.
*/
-void fastcall __fput(struct file *file)
+void __fput(struct file *file)
{
- struct dentry *dentry = file->f_dentry;
- struct vfsmount *mnt = file->f_vfsmnt;
+ struct dentry *dentry = file->f_path.dentry;
+ struct vfsmount *mnt = file->f_path.mnt;
struct inode *inode = dentry->d_inode;
might_sleep();
eventpoll_release(file);
locks_remove_flock(file);
+ if (unlikely(file->f_flags & FASYNC)) {
+ if (file->f_op && file->f_op->fasync)
+ file->f_op->fasync(-1, file, 0);
+ }
if (file->f_op && file->f_op->release)
file->f_op->release(inode, file);
security_file_free(file);
- if (unlikely(inode->i_cdev != NULL))
+ ima_file_free(file);
+ if (unlikely(S_ISCHR(inode->i_mode) && inode->i_cdev != NULL))
cdev_put(inode->i_cdev);
fops_put(file->f_op);
- if (file->f_mode & FMODE_WRITE)
- put_write_access(inode);
+ put_pid(file->f_owner.pid);
file_kill(file);
- file->f_dentry = NULL;
- file->f_vfsmnt = NULL;
+ if (file->f_mode & FMODE_WRITE)
+ drop_file_write_access(file);
+ file->f_path.dentry = NULL;
+ file->f_path.mnt = NULL;
file_free(file);
dput(dentry);
mntput(mnt);
}
-struct file fastcall *fget(unsigned int fd)
+struct file *fget(unsigned int fd)
{
struct file *file;
struct files_struct *files = current->files;
- spin_lock(&files->file_lock);
+ rcu_read_lock();
file = fcheck_files(files, fd);
- if (file)
- get_file(file);
- spin_unlock(&files->file_lock);
+ if (file) {
+ if (!atomic_long_inc_not_zero(&file->f_count)) {
+ /* File object ref couldn't be taken */
+ rcu_read_unlock();
+ return NULL;
+ }
+ }
+ rcu_read_unlock();
+
return file;
}
* and a flag is returned to be passed to the corresponding fput_light().
* There must not be a cloning between an fget_light/fput_light pair.
*/
-struct file fastcall *fget_light(unsigned int fd, int *fput_needed)
+struct file *fget_light(unsigned int fd, int *fput_needed)
{
struct file *file;
struct files_struct *files = current->files;
if (likely((atomic_read(&files->count) == 1))) {
file = fcheck_files(files, fd);
} else {
- spin_lock(&files->file_lock);
+ rcu_read_lock();
file = fcheck_files(files, fd);
if (file) {
- get_file(file);
- *fput_needed = 1;
+ if (atomic_long_inc_not_zero(&file->f_count))
+ *fput_needed = 1;
+ else
+ /* Didn't get the reference, someone's freed */
+ file = NULL;
}
- spin_unlock(&files->file_lock);
+ rcu_read_unlock();
}
+
return file;
}
void put_filp(struct file *file)
{
- if (atomic_dec_and_test(&file->f_count)) {
+ if (atomic_long_dec_and_test(&file->f_count)) {
security_file_free(file);
file_kill(file);
file_free(file);
if (!list)
return;
file_list_lock();
- list_move(&file->f_list, list);
+ list_move(&file->f_u.fu_list, list);
file_list_unlock();
}
void file_kill(struct file *file)
{
- if (!list_empty(&file->f_list)) {
+ if (!list_empty(&file->f_u.fu_list)) {
file_list_lock();
- list_del_init(&file->f_list);
+ list_del_init(&file->f_u.fu_list);
file_list_unlock();
}
}
int fs_may_remount_ro(struct super_block *sb)
{
- struct list_head *p;
+ struct file *file;
/* Check that no files are currently opened for writing. */
file_list_lock();
- list_for_each(p, &sb->s_files) {
- struct file *file = list_entry(p, struct file, f_list);
- struct inode *inode = file->f_dentry->d_inode;
+ list_for_each_entry(file, &sb->s_files, f_u.fu_list) {
+ struct inode *inode = file->f_path.dentry->d_inode;
/* File with pending delete? */
if (inode->i_nlink == 0)
return 0;
}
+/**
+ * mark_files_ro - mark all files read-only
+ * @sb: superblock in question
+ *
+ * All files are marked read-only. We don't care about pending
+ * delete files so this should be used in 'force' mode only.
+ */
+void mark_files_ro(struct super_block *sb)
+{
+ struct file *f;
+
+retry:
+ file_list_lock();
+ list_for_each_entry(f, &sb->s_files, f_u.fu_list) {
+ struct vfsmount *mnt;
+ if (!S_ISREG(f->f_path.dentry->d_inode->i_mode))
+ continue;
+ if (!file_count(f))
+ continue;
+ if (!(f->f_mode & FMODE_WRITE))
+ continue;
+ spin_lock(&f->f_lock);
+ f->f_mode &= ~FMODE_WRITE;
+ spin_unlock(&f->f_lock);
+ if (file_check_writeable(f) != 0)
+ continue;
+ file_release_write(f);
+ mnt = mntget(f->f_path.mnt);
+ file_list_unlock();
+ /*
+ * This can sleep, so we can't hold
+ * the file_list_lock() spinlock.
+ */
+ mnt_drop_write(mnt);
+ mntput(mnt);
+ goto retry;
+ }
+ file_list_unlock();
+}
+
void __init files_init(unsigned long mempages)
{
int n;
- /* One file with associated inode and dcache is very roughly 1K.
+
+ filp_cachep = kmem_cache_create("filp", sizeof(struct file), 0,
+ SLAB_HWCACHE_ALIGN | SLAB_PANIC, NULL);
+
+ /*
+ * One file with associated inode and dcache is very roughly 1K.
* Per default don't use more than 10% of our memory for files.
*/
files_stat.max_files = n;
if (files_stat.max_files < NR_FILE)
files_stat.max_files = NR_FILE;
+ files_defer_init();
+ percpu_counter_init(&nr_files, 0);
}
git://ftp.safe.ca / safe / jmp / linux-2.6 / blobdiff