1 files changed, 102 insertions, 271 deletions

diff --git a/fs/file_table.c b/fs/file_table.c
index eb36b6b17e2..385bfd31512 100644
--- a/fs/file_table.c
+++ b/fs/file_table.c
@@ -23,9 +23,11 @@
 #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 <asm/atomic.h>
+#include <linux/atomic.h>
 
 #include "internal.h"
 
@@ -34,15 +36,12 @@ struct files_stat_struct files_stat = {
 	.max_files = NR_FILE
 };
 
-DECLARE_LGLOCK(files_lglock);
-DEFINE_LGLOCK(files_lglock);
-
 /* 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)
+static void file_free_rcu(struct rcu_head *head)
 {
 	struct file *f = container_of(head, struct file, f_u.fu_rcuhead);
 
@@ -53,7 +52,6 @@ static inline void file_free_rcu(struct rcu_head *head)
 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);
 }
 
@@ -78,14 +76,14 @@ EXPORT_SYMBOL_GPL(get_max_files);
  * Handle nr_files sysctl
  */
 #if defined(CONFIG_SYSCTL) && defined(CONFIG_PROC_FS)
-int proc_nr_files(ctl_table *table, int write,
+int proc_nr_files(struct ctl_table *table, int write,
                      void __user *buffer, size_t *lenp, loff_t *ppos)
 {
 	files_stat.nr_files = get_nr_files();
 	return proc_doulongvec_minmax(table, write, buffer, lenp, ppos);
 }
 #else
-int proc_nr_files(ctl_table *table, int write,
+int proc_nr_files(struct ctl_table *table, int write,
                      void __user *buffer, size_t *lenp, loff_t *ppos)
 {
 	return -ENOSYS;
@@ -93,8 +91,8 @@ int proc_nr_files(ctl_table *table, int write,
 #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
@@ -106,7 +104,8 @@ struct file *get_empty_filp(void)
 {
 	const struct cred *cred = current_cred();
 	static long old_max;
-	struct file * f;
+	struct file *f;
+	int error;
 
 	/*
 	 * Privileged users can go above max_files
@@ -121,18 +120,21 @@ struct file *get_empty_filp(void)
 	}
 
 	f = kmem_cache_zalloc(filp_cachep, GFP_KERNEL);
-	if (f == NULL)
-		goto fail;
+	if (unlikely(!f))
+		return ERR_PTR(-ENOMEM);
 
 	percpu_counter_inc(&nr_files);
 	f->f_cred = get_cred(cred);
-	if (security_file_alloc(f))
-		goto fail_sec;
+	error = security_file_alloc(f);
+	if (unlikely(error)) {
+		file_free(f);
+		return ERR_PTR(error);
+	}
 
-	INIT_LIST_HEAD(&f->f_u.fu_list);
 	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 */
 	return f;
@@ -143,12 +145,7 @@ over:
 		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);
 }
 
 /**
@@ -172,61 +169,33 @@ struct file *alloc_file(struct path *path, fmode_t mode,
 	struct file *file;
 
 	file = get_empty_filp();
-	if (!file)
-		return NULL;
+	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;
-
-	/*
-	 * 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);
+	if ((mode & (FMODE_READ | FMODE_WRITE)) == FMODE_READ)
+		i_readcount_inc(path->dentry->d_inode);
 	return file;
 }
 EXPORT_SYMBOL(alloc_file);
 
-/**
- * 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);
-
 /* the real guts of fput() - releasing the last reference to file
  */
 static void __fput(struct file *file)
 {
 	struct dentry *dentry = file->f_path.dentry;
 	struct vfsmount *mnt = file->f_path.mnt;
-	struct inode *inode = dentry->d_inode;
+	struct inode *inode = file->f_inode;
 
 	might_sleep();
 
@@ -236,252 +205,116 @@ static void __fput(struct file *file)
 	 * in the file cleanup chain.
 	 */
 	eventpoll_release(file);
-	locks_remove_flock(file);
+	locks_remove_file(file);
 
 	if (unlikely(file->f_flags & FASYNC)) {
-		if (file->f_op && file->f_op->fasync)
+		if (file->f_op->fasync)
 			file->f_op->fasync(-1, file, 0);
 	}
-	if (file->f_op && file->f_op->release)
+	ima_file_free(file);
+	if (file->f_op->release)
 		file->f_op->release(inode, file);
 	security_file_free(file);
-	ima_file_free(file);
-	if (unlikely(S_ISCHR(inode->i_mode) && 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);
 	put_pid(file->f_owner.pid);
-	file_sb_list_del(file);
-	if (file->f_mode & FMODE_WRITE)
-		drop_file_write_access(file);
+	if ((file->f_mode & (FMODE_READ | FMODE_WRITE)) == FMODE_READ)
+		i_readcount_dec(inode);
+	if (file->f_mode & FMODE_WRITER) {
+		put_write_access(inode);
+		__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);
 }
 
-void fput(struct file *file)
+static LLIST_HEAD(delayed_fput_list);
+static void delayed_fput(struct work_struct *unused)
 {
-	if (atomic_long_dec_and_test(&file->f_count))
-		__fput(file);
-}
-
-EXPORT_SYMBOL(fput);
+	struct llist_node *node = llist_del_all(&delayed_fput_list);
+	struct llist_node *next;
 
-struct file *fget(unsigned int fd)
-{
-	struct file *file;
-	struct files_struct *files = current->files;
-
-	rcu_read_lock();
-	file = fcheck_files(files, fd);
-	if (file) {
-		if (!atomic_long_inc_not_zero(&file->f_count)) {
-			/* File object ref couldn't be taken */
-			rcu_read_unlock();
-			return NULL;
-		}
+	for (; node; node = next) {
+		next = llist_next(node);
+		__fput(llist_entry(node, struct file, f_u.fu_llist));
 	}
-	rcu_read_unlock();
-
-	return file;
 }
 
-EXPORT_SYMBOL(fget);
-
-/*
- * Lightweight file lookup - no refcnt increment if fd table isn't shared.
- *
- * You can use this instead of fget if you satisfy all of the following
- * conditions:
- * 1) You must call fput_light before exiting the syscall and returning control
- *    to userspace (i.e. you cannot remember the returned struct file * after
- *    returning to userspace).
- * 2) You must not call filp_close on the returned struct file * in between
- *    calls to fget_light and fput_light.
- * 3) You must not clone the current task in between the calls to fget_light
- *    and fput_light.
- *
- * The fput_needed flag returned by fget_light should be passed to the
- * corresponding fput_light.
- */
-struct file *fget_light(unsigned int fd, int *fput_needed)
+static void ____fput(struct callback_head *work)
 {
-	struct file *file;
-	struct files_struct *files = current->files;
-
-	*fput_needed = 0;
-	if (atomic_read(&files->count) == 1) {
-		file = fcheck_files(files, fd);
-	} else {
-		rcu_read_lock();
-		file = fcheck_files(files, fd);
-		if (file) {
-			if (atomic_long_inc_not_zero(&file->f_count))
-				*fput_needed = 1;
-			else
-				/* Didn't get the reference, someone's freed */
-				file = NULL;
-		}
-		rcu_read_unlock();
-	}
-
-	return file;
+	__fput(container_of(work, struct file, f_u.fu_rcuhead));
 }
 
-void put_filp(struct file *file)
-{
-	if (atomic_long_dec_and_test(&file->f_count)) {
-		security_file_free(file);
-		file_sb_list_del(file);
-		file_free(file);
-	}
-}
-
-static inline int file_list_cpu(struct file *file)
+/*
+ * 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.
+ */
+void flush_delayed_fput(void)
 {
-#ifdef CONFIG_SMP
-	return file->f_sb_list_cpu;
-#else
-	return smp_processor_id();
-#endif
+	delayed_fput(NULL);
 }
 
-/* helper for file_sb_list_add to reduce ifdefs */
-static inline void __file_sb_list_add(struct file *file, struct super_block *sb)
-{
-	struct list_head *list;
-#ifdef CONFIG_SMP
-	int cpu;
-	cpu = smp_processor_id();
-	file->f_sb_list_cpu = cpu;
-	list = per_cpu_ptr(sb->s_files, cpu);
-#else
-	list = &sb->s_files;
-#endif
-	list_add(&file->f_u.fu_list, list);
-}
+static DECLARE_DELAYED_WORK(delayed_fput_work, delayed_fput);
 
-/**
- * file_sb_list_add - add a file to the sb's file list
- * @file: file to add
- * @sb: sb to add it to
- *
- * Use this function to associate a file with the superblock of the inode it
- * refers to.
- */
-void file_sb_list_add(struct file *file, struct super_block *sb)
+void fput(struct file *file)
 {
-	lg_local_lock(files_lglock);
-	__file_sb_list_add(file, sb);
-	lg_local_unlock(files_lglock);
-}
+	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.
+			 */
+		}
 
-/**
- * file_sb_list_del - remove a file from the sb's file list
- * @file: file to remove
- * @sb: sb to remove it from
- *
- * Use this function to remove a file from its superblock.
- */
-void file_sb_list_del(struct file *file)
-{
-	if (!list_empty(&file->f_u.fu_list)) {
-		lg_local_lock_cpu(files_lglock, file_list_cpu(file));
-		list_del_init(&file->f_u.fu_list);
-		lg_local_unlock_cpu(files_lglock, file_list_cpu(file));
+		if (llist_add(&file->f_u.fu_llist, &delayed_fput_list))
+			schedule_delayed_work(&delayed_fput_work, 1);
 	}
 }
 
-#ifdef CONFIG_SMP
-
 /*
- * These macros iterate all files on all CPUs for a given superblock.
- * files_lglock must be held globally.
+ * 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.
  */
-#define do_file_list_for_each_entry(__sb, __file)		\
-{								\
-	int i;							\
-	for_each_possible_cpu(i) {				\
-		struct list_head *list;				\
-		list = per_cpu_ptr((__sb)->s_files, i);		\
-		list_for_each_entry((__file), list, f_u.fu_list)
-
-#define while_file_list_for_each_entry				\
-	}							\
-}
-
-#else
-
-#define do_file_list_for_each_entry(__sb, __file)		\
-{								\
-	struct list_head *list;					\
-	list = &(sb)->s_files;					\
-	list_for_each_entry((__file), list, f_u.fu_list)
-
-#define while_file_list_for_each_entry				\
-}
-
-#endif
-
-int fs_may_remount_ro(struct super_block *sb)
+void __fput_sync(struct file *file)
 {
-	struct file *file;
-	/* Check that no files are currently opened for writing. */
-	lg_global_lock(files_lglock);
-	do_file_list_for_each_entry(sb, file) {
-		struct inode *inode = file->f_path.dentry->d_inode;
-
-		/* File with pending delete? */
-		if (inode->i_nlink == 0)
-			goto too_bad;
-
-		/* Writeable file? */
-		if (S_ISREG(inode->i_mode) && (file->f_mode & FMODE_WRITE))
-			goto too_bad;
-	} while_file_list_for_each_entry;
-	lg_global_unlock(files_lglock);
-	return 1; /* Tis' cool bro. */
-too_bad:
-	lg_global_unlock(files_lglock);
-	return 0;
+	if (atomic_long_dec_and_test(&file->f_count)) {
+		struct task_struct *task = current;
+		BUG_ON(!(task->flags & PF_KTHREAD));
+		__fput(file);
+	}
 }
 
-/**
- *	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;
+EXPORT_SYMBOL(fput);
 
-retry:
-	lg_global_lock(files_lglock);
-	do_file_list_for_each_entry(sb, f) {
-		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);
-		/* This can sleep, so we can't hold the spinlock. */
-		lg_global_unlock(files_lglock);
-		mnt_drop_write(mnt);
-		mntput(mnt);
-		goto retry;
-	} while_file_list_for_each_entry;
-	lg_global_unlock(files_lglock);
+void put_filp(struct file *file)
+{
+	if (atomic_long_dec_and_test(&file->f_count)) {
+		security_file_free(file);
+		file_free(file);
+	}
 }
 
 void __init files_init(unsigned long mempages)
@@ -498,7 +331,5 @@ void __init files_init(unsigned long mempages)
 
 	n = (mempages * (PAGE_SIZE / 1024)) / 10;
 	files_stat.max_files = max_t(unsigned long, n, NR_FILE);
-	files_defer_init();
-	lg_lock_init(files_lglock);
 	percpu_counter_init(&nr_files, 0);
 }