vfs: make open_with_fake_path() not contribute to nr_files (d3b1084d) · Commits · 戴 / test

fs/file_table.c

+48 −21

Original line number	Original line	Diff line number	Diff line
	@@ -52,6 +52,7 @@ static void file_free_rcu(struct rcu_head *head)
	static inline void file_free(struct file *f)		static inline void file_free(struct file *f)
	{		{
	security_file_free(f);		security_file_free(f);
			if (!(f->f_mode & FMODE_NOACCOUNT))
	percpu_counter_dec(&nr_files);		percpu_counter_dec(&nr_files);
	call_rcu(&f->f_u.fu_rcuhead, file_free_rcu);		call_rcu(&f->f_u.fu_rcuhead, file_free_rcu);
	}		}
	@@ -91,6 +92,34 @@ int proc_nr_files(struct ctl_table *table, int write,
	}		}
	#endif		#endif

			static struct file __alloc_file(int flags, const struct cred cred)
			{
			struct file *f;
			int error;

			f = kmem_cache_zalloc(filp_cachep, GFP_KERNEL);
			if (unlikely(!f))
			return ERR_PTR(-ENOMEM);

			f->f_cred = get_cred(cred);
			error = security_file_alloc(f);
			if (unlikely(error)) {
			file_free_rcu(&f->f_u.fu_rcuhead);
			return ERR_PTR(error);
			}

			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_flags = flags;
			f->f_mode = OPEN_FMODE(flags);
			/* f->f_version: 0 */

			return f;
			}

	/* Find an unused file structure and return a pointer to it.		/* Find an unused file structure and return a pointer to it.
	* Returns an error pointer if some error happend e.g. we over file		* Returns an error pointer if some error happend e.g. we over file
	* structures limit, run out of memory or operation is not permitted.		* structures limit, run out of memory or operation is not permitted.
	@@ -105,7 +134,6 @@ struct file alloc_empty_file(int flags, const struct cred cred)
	{		{
	static long old_max;		static long old_max;
	struct file *f;		struct file *f;
	int error;

	/*		/*
	* Privileged users can go above max_files		* Privileged users can go above max_files
	@@ -119,26 +147,10 @@ struct file alloc_empty_file(int flags, const struct cred cred)
	goto over;		goto over;
	}		}

	f = kmem_cache_zalloc(filp_cachep, GFP_KERNEL);		f = __alloc_file(flags, cred);
	if (unlikely(!f))		if (!IS_ERR(f))
	return ERR_PTR(-ENOMEM);

	f->f_cred = get_cred(cred);
	error = security_file_alloc(f);
	if (unlikely(error)) {
	file_free_rcu(&f->f_u.fu_rcuhead);
	return ERR_PTR(error);
	}

	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_flags = flags;
	f->f_mode = OPEN_FMODE(flags);
	/* f->f_version: 0 */
	percpu_counter_inc(&nr_files);		percpu_counter_inc(&nr_files);

	return f;		return f;

	over:		over:
	@@ -150,6 +162,21 @@ over:
	return ERR_PTR(-ENFILE);		return ERR_PTR(-ENFILE);
	}		}

			/*
			* Variant of alloc_empty_file() that doesn't check and modify nr_files.
			*
			* Should not be used unless there's a very good reason to do so.
			*/
			struct file alloc_empty_file_noaccount(int flags, const struct cred cred)
			{
			struct file *f = __alloc_file(flags, cred);

			if (!IS_ERR(f))
			f->f_mode \|= FMODE_NOACCOUNT;

			return f;
			}

	/**		/**
	* alloc_file - allocate and initialize a 'struct file'		* alloc_file - allocate and initialize a 'struct file'
	*		*

fs/internal.h

+1 −0

Original line number	Original line	Diff line number	Diff line
	@@ -94,6 +94,7 @@ extern void chroot_fs_refs(const struct path , const struct path );
	* file_table.c		* file_table.c
	*/		*/
	extern struct file alloc_empty_file(int, const struct cred );		extern struct file alloc_empty_file(int, const struct cred );
			extern struct file alloc_empty_file_noaccount(int, const struct cred );

	/*		/*
	* super.c		* super.c

fs/open.c

+1 −1

Original line number	Original line	Diff line number	Diff line
	@@ -928,7 +928,7 @@ EXPORT_SYMBOL(dentry_open);
	struct file open_with_fake_path(const struct path path, int flags,		struct file open_with_fake_path(const struct path path, int flags,
	struct inode inode, const struct cred cred)		struct inode inode, const struct cred cred)
	{		{
	struct file *f = alloc_empty_file(flags, cred);		struct file *f = alloc_empty_file_noaccount(flags, cred);
	if (!IS_ERR(f)) {		if (!IS_ERR(f)) {
	int error;		int error;

include/linux/fs.h

+3 −0

Original line number	Original line	Diff line number	Diff line
	@@ -156,6 +156,9 @@ typedef int (dio_iodone_t)(struct kiocb *iocb, loff_t offset,
	/* File is capable of returning -EAGAIN if I/O will block */		/* File is capable of returning -EAGAIN if I/O will block */
	#define FMODE_NOWAIT ((__force fmode_t)0x8000000)		#define FMODE_NOWAIT ((__force fmode_t)0x8000000)

			/* File does not contribute to nr_files count */
			#define FMODE_NOACCOUNT ((__force fmode_t)0x20000000)

	/*		/*
	* Flag for rw_copy_check_uvector and compat_rw_copy_check_uvector		* Flag for rw_copy_check_uvector and compat_rw_copy_check_uvector
	* that indicates that they should check the contents of the iovec are		* that indicates that they should check the contents of the iovec are

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