1 files changed, 220 insertions, 163 deletions

diff --git a/fs/file_table.c b/fs/file_table.c
index c3a5e2fd663..385bfd31512 100644
--- a/fs/file_table.c
+++ b/fs/file_table.c
@@ -8,129 +8,194 @@
 #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/lglock.h>
+#include <linux/percpu_counter.h>
+#include <linux/percpu.h>
+#include <linux/hardirq.h>
+#include <linux/task_work.h>
+#include <linux/ima.h>
+
+#include <linux/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 */
+/* SLAB cache for file structures */
+static struct kmem_cache *filp_cachep __read_mostly;
 
-/* public. Not pretty! */
- __cacheline_aligned_in_smp DEFINE_SPINLOCK(files_lock);
+static struct percpu_counter nr_files __cacheline_aligned_in_smp;
 
-static DEFINE_SPINLOCK(filp_count_lock);
+static void file_free_rcu(struct rcu_head *head)
+{
+	struct file *f = container_of(head, struct file, f_u.fu_rcuhead);
 
-/* slab constructors and destructors are called from arbitrary
- * context and must be fully threaded - use a local spinlock
- * to protect files_stat.nr_files
- */
-void filp_ctor(void *objp, struct kmem_cache *cachep, unsigned long cflags)
+	put_cred(f->f_cred);
+	kmem_cache_free(filp_cachep, f);
+}
+
+static inline void file_free(struct file *f)
 {
-	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);
-	}
+	percpu_counter_dec(&nr_files);
+	call_rcu(&f->f_u.fu_rcuhead, file_free_rcu);
 }
 
-void filp_dtor(void *objp, struct kmem_cache *cachep, unsigned long dflags)
+/*
+ * Return the total number of open files in the system
+ */
+static long get_nr_files(void)
 {
-	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);
 }
 
-static inline void file_free_rcu(struct rcu_head *head)
+/*
+ * Return the maximum number of open files in the system
+ */
+unsigned long get_max_files(void)
 {
-	struct file *f =  container_of(head, struct file, f_u.fu_rcuhead);
-	kmem_cache_free(filp_cachep, f);
+	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(struct ctl_table *table, int write,
+                     void __user *buffer, size_t *lenp, loff_t *ppos)
 {
-	call_rcu(&f->f_u.fu_rcuhead, file_free_rcu);
+	files_stat.nr_files = get_nr_files();
+	return proc_doulongvec_minmax(table, write, buffer, lenp, ppos);
 }
+#else
+int proc_nr_files(struct 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.
+ * Returns an error pointer if some error happend e.g. we over file
+ * structures limit, run out of memory or operation is not permitted.
+ *
+ * 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)
 {
-	static int old_max;
-	struct file * f;
+	const struct cred *cred = current_cred();
+	static long old_max;
+	struct file *f;
+	int error;
 
 	/*
 	 * 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);
-	if (f == NULL)
-		goto fail;
+	f = kmem_cache_zalloc(filp_cachep, GFP_KERNEL);
+	if (unlikely(!f))
+		return ERR_PTR(-ENOMEM);
 
-	memset(f, 0, sizeof(*f));
-	if (security_file_alloc(f))
-		goto fail_sec;
+	percpu_counter_inc(&nr_files);
+	f->f_cred = get_cred(cred);
+	error = security_file_alloc(f);
+	if (unlikely(error)) {
+		file_free(f);
+		return ERR_PTR(error);
+	}
 
-	eventpoll_init_file(f);
-	atomic_set(&f->f_count, 1);
-	f->f_uid = current->fsuid;
-	f->f_gid = current->fsgid;
+	atomic_long_set(&f->f_count, 1);
 	rwlock_init(&f->f_owner.lock);
+	spin_lock_init(&f->f_lock);
+	mutex_init(&f->f_pos_lock);
+	eventpoll_init_file(f);
 	/* f->f_version: 0 */
-	INIT_LIST_HEAD(&f->f_u.fu_list);
 	return f;
 
 over:
 	/* Ran out of filps - report that */
-	if (files_stat.nr_files > old_max) {
-		printk(KERN_INFO "VFS: file-max limit %d reached\n",
-					files_stat.max_files);
-		old_max = files_stat.nr_files;
+	if (get_nr_files() > old_max) {
+		pr_info("VFS: file-max limit %lu reached\n", get_max_files());
+		old_max = get_nr_files();
 	}
-	goto fail;
-
-fail_sec:
-	file_free(f);
-fail:
-	return NULL;
+	return ERR_PTR(-ENFILE);
 }
 
-EXPORT_SYMBOL(get_empty_filp);
-
-void fastcall fput(struct file *file)
+/**
+ * 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)
 {
-	if (rcuref_dec_and_test(&file->f_count))
-		__fput(file);
-}
+	struct file *file;
 
-EXPORT_SYMBOL(fput);
+	file = get_empty_filp();
+	if (IS_ERR(file))
+		return file;
+
+	file->f_path = *path;
+	file->f_inode = path->dentry->d_inode;
+	file->f_mapping = path->dentry->d_inode->i_mapping;
+	if ((mode & FMODE_READ) &&
+	     likely(fop->read || fop->aio_read || fop->read_iter))
+		mode |= FMODE_CAN_READ;
+	if ((mode & FMODE_WRITE) &&
+	     likely(fop->write || fop->aio_write || fop->write_iter))
+		mode |= FMODE_CAN_WRITE;
+	file->f_mode = mode;
+	file->f_op = fop;
+	if ((mode & (FMODE_READ | FMODE_WRITE)) == FMODE_READ)
+		i_readcount_inc(path->dentry->d_inode);
+	return file;
+}
+EXPORT_SYMBOL(alloc_file);
 
-/* __fput is called from task context when aio completion releases the last
- * last use of a struct file *.  Do not use otherwise.
+/* the real guts of fput() - releasing the last reference to file
  */
-void fastcall __fput(struct file *file)
+static void __fput(struct file *file)
 {
-	struct dentry *dentry = file->f_dentry;
-	struct vfsmount *mnt = file->f_vfsmnt;
-	struct inode *inode = dentry->d_inode;
+	struct dentry *dentry = file->f_path.dentry;
+	struct vfsmount *mnt = file->f_path.mnt;
+	struct inode *inode = file->f_inode;
 
 	might_sleep();
 
@@ -140,139 +205,131 @@ void fastcall __fput(struct file *file)
 	 * in the file cleanup chain.
 	 */
 	eventpoll_release(file);
-	locks_remove_flock(file);
+	locks_remove_file(file);
 
-	if (file->f_op && file->f_op->release)
+	if (unlikely(file->f_flags & FASYNC)) {
+		if (file->f_op->fasync)
+			file->f_op->fasync(-1, file, 0);
+	}
+	ima_file_free(file);
+	if (file->f_op->release)
 		file->f_op->release(inode, file);
 	security_file_free(file);
-	if (unlikely(inode->i_cdev != NULL))
+	if (unlikely(S_ISCHR(inode->i_mode) && inode->i_cdev != NULL &&
+		     !(file->f_mode & FMODE_PATH))) {
 		cdev_put(inode->i_cdev);
+	}
 	fops_put(file->f_op);
-	if (file->f_mode & FMODE_WRITE)
+	put_pid(file->f_owner.pid);
+	if ((file->f_mode & (FMODE_READ | FMODE_WRITE)) == FMODE_READ)
+		i_readcount_dec(inode);
+	if (file->f_mode & FMODE_WRITER) {
 		put_write_access(inode);
-	file_kill(file);
-	file->f_dentry = NULL;
-	file->f_vfsmnt = NULL;
+		__mnt_drop_write(mnt);
+	}
+	file->f_path.dentry = NULL;
+	file->f_path.mnt = NULL;
+	file->f_inode = NULL;
 	file_free(file);
 	dput(dentry);
 	mntput(mnt);
 }
 
-struct file fastcall *fget(unsigned int fd)
+static LLIST_HEAD(delayed_fput_list);
+static void delayed_fput(struct work_struct *unused)
 {
-	struct file *file;
-	struct files_struct *files = current->files;
-
-	rcu_read_lock();
-	file = fcheck_files(files, fd);
-	if (file) {
-		if (!rcuref_inc_lf(&file->f_count)) {
-			/* File object ref couldn't be taken */
-			rcu_read_unlock();
-			return NULL;
-		}
-	}
-	rcu_read_unlock();
+	struct llist_node *node = llist_del_all(&delayed_fput_list);
+	struct llist_node *next;
 
-	return file;
+	for (; node; node = next) {
+		next = llist_next(node);
+		__fput(llist_entry(node, struct file, f_u.fu_llist));
+	}
 }
 
-EXPORT_SYMBOL(fget);
+static void ____fput(struct callback_head *work)
+{
+	__fput(container_of(work, struct file, f_u.fu_rcuhead));
+}
 
 /*
- * Lightweight file lookup - no refcnt increment if fd table isn't shared. 
- * You can use this only if it is guranteed that the current task already 
- * holds a refcnt to that file. That check has to be done at fget() only
- * 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.
+ * If kernel thread really needs to have the final fput() it has done
+ * to complete, call this.  The only user right now is the boot - we
+ * *do* need to make sure our writes to binaries on initramfs has
+ * not left us with opened struct file waiting for __fput() - execve()
+ * won't work without that.  Please, don't add more callers without
+ * very good reasons; in particular, never call that with locks
+ * held and never call that from a thread that might need to do
+ * some work on any kind of umount.
  */
-struct file fastcall *fget_light(unsigned int fd, int *fput_needed)
+void flush_delayed_fput(void)
 {
-	struct file *file;
-	struct files_struct *files = current->files;
-
-	*fput_needed = 0;
-	if (likely((atomic_read(&files->count) == 1))) {
-		file = fcheck_files(files, fd);
-	} else {
-		rcu_read_lock();
-		file = fcheck_files(files, fd);
-		if (file) {
-			if (rcuref_inc_lf(&file->f_count))
-				*fput_needed = 1;
-			else
-				/* Didn't get the reference, someone's freed */
-				file = NULL;
-		}
-		rcu_read_unlock();
-	}
-
-	return file;
+	delayed_fput(NULL);
 }
 
+static DECLARE_DELAYED_WORK(delayed_fput_work, delayed_fput);
 
-void put_filp(struct file *file)
+void fput(struct file *file)
 {
-	if (rcuref_dec_and_test(&file->f_count)) {
-		security_file_free(file);
-		file_kill(file);
-		file_free(file);
-	}
-}
+	if (atomic_long_dec_and_test(&file->f_count)) {
+		struct task_struct *task = current;
+
+		if (likely(!in_interrupt() && !(task->flags & PF_KTHREAD))) {
+			init_task_work(&file->f_u.fu_rcuhead, ____fput);
+			if (!task_work_add(task, &file->f_u.fu_rcuhead, true))
+				return;
+			/*
+			 * After this task has run exit_task_work(),
+			 * task_work_add() will fail.  Fall through to delayed
+			 * fput to avoid leaking *file.
+			 */
+		}
 
-void file_move(struct file *file, struct list_head *list)
-{
-	if (!list)
-		return;
-	file_list_lock();
-	list_move(&file->f_u.fu_list, list);
-	file_list_unlock();
+		if (llist_add(&file->f_u.fu_llist, &delayed_fput_list))
+			schedule_delayed_work(&delayed_fput_work, 1);
+	}
 }
 
-void file_kill(struct file *file)
+/*
+ * synchronous analog of fput(); for kernel threads that might be needed
+ * in some umount() (and thus can't use flush_delayed_fput() without
+ * risking deadlocks), need to wait for completion of __fput() and know
+ * for this specific struct file it won't involve anything that would
+ * need them.  Use only if you really need it - at the very least,
+ * don't blindly convert fput() by kernel thread to that.
+ */
+void __fput_sync(struct file *file)
 {
-	if (!list_empty(&file->f_u.fu_list)) {
-		file_list_lock();
-		list_del_init(&file->f_u.fu_list);
-		file_list_unlock();
+	if (atomic_long_dec_and_test(&file->f_count)) {
+		struct task_struct *task = current;
+		BUG_ON(!(task->flags & PF_KTHREAD));
+		__fput(file);
 	}
 }
 
-int fs_may_remount_ro(struct super_block *sb)
-{
-	struct list_head *p;
-
-	/* 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_u.fu_list);
-		struct inode *inode = file->f_dentry->d_inode;
-
-		/* File with pending delete? */
-		if (inode->i_nlink == 0)
-			goto too_bad;
+EXPORT_SYMBOL(fput);
 
-		/* Writeable file? */
-		if (S_ISREG(inode->i_mode) && (file->f_mode & FMODE_WRITE))
-			goto too_bad;
+void put_filp(struct file *file)
+{
+	if (atomic_long_dec_and_test(&file->f_count)) {
+		security_file_free(file);
+		file_free(file);
 	}
-	file_list_unlock();
-	return 1; /* Tis' cool bro. */
-too_bad:
-	file_list_unlock();
-	return 0;
 }
 
 void __init files_init(unsigned long mempages)
 { 
-	int n; 
-	/* One file with associated inode and dcache is very roughly 1K. 
+	unsigned long n;
+
+	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. 
 	 */ 
 
 	n = (mempages * (PAGE_SIZE / 1024)) / 10;
-	files_stat.max_files = n; 
-	if (files_stat.max_files < NR_FILE)
-		files_stat.max_files = NR_FILE;
-	files_defer_init();
+	files_stat.max_files = max_t(unsigned long, n, NR_FILE);
+	percpu_counter_init(&nr_files, 0);
 }