3  *  linux/fs/file.c
17 #include <linux/file.h>
53  * space if any.  This does not copy the file pointers.  Called with the files
70  * Copy all file descriptors from the old table to the new, expanded table and
79 	cpy = ofdt->max_fds * sizeof(struct file *);  in copy_fdtable()
80 	set = (nfdt->max_fds - ofdt->max_fds) * sizeof(struct file *);  in copy_fdtable()
114 	nr /= (1024 / sizeof(struct file *));  in alloc_fdtable()
116 	nr *= (1024 / sizeof(struct file *));  in alloc_fdtable()
133 	data = kvmalloc_array(nr, sizeof(struct file *), GFP_KERNEL_ACCOUNT);  in alloc_fdtable()
160  * Expand the file descriptor table.
205  * This function will expand the file structures, if the requested size exceeds
302 	struct file **old_fds, **new_fds;  in dup_fd()
371 	 * the file can show up as we are walking the array below.  in dup_fd()
377 	 * ref the file if we see it and mark the fd slot as unused otherwise.  in dup_fd()
380 		struct file *f = rcu_dereference_raw(*old_fds++);  in dup_fd()
391 	memset(new_fds, 0, (new_fdt->max_fds - open_files) * sizeof(struct file *));  in dup_fd()
420 				struct file * file = xchg(&fdt->fd[i], NULL);  in close_files()  local
421 				if (file) {  in close_files()
422 					filp_close(file, files);  in close_files()
487  * allocate a file descriptor, mark it busy.
577  * Install a file pointer in the fd array.
580  * setting the open_fds bitmap and installing the file in the file
582  * installing a file in the array before us.  We need to detect this and
583  * fput() the struct file we are about to overwrite in this case.
588  * This consumes the "file" refcount, so callers should treat it
589  * as if they had called fput(file).
592 void fd_install(unsigned int fd, struct file *file)  in fd_install()  argument
604 		rcu_assign_pointer(fdt->fd[fd], file);  in fd_install()
612 	rcu_assign_pointer(fdt->fd[fd], file);  in fd_install()
619  * pick_file - return file associatd with fd
620  * @files: file struct to retrieve file from
621  * @fd: file descriptor to retrieve file for
625  * Returns: The file associated with @fd (NULL if @fd is not open)
627 static struct file *pick_file(struct files_struct *files, unsigned fd)  in pick_file()
630 	struct file *file;  in pick_file()  local
636 	file = rcu_dereference_raw(fdt->fd[fd]);  in pick_file()
637 	if (file) {  in pick_file()
641 	return file;  in pick_file()
647 	struct file *file;  in close_fd()  local
650 	file = pick_file(files, fd);  in close_fd()
652 	if (!file)  in close_fd()
655 	return filp_close(file, files);  in close_fd()
661  * @fdt: File descriptor table.
689 	struct file *file;  in __range_close()  local
697 		file = pick_file(files, fd);  in __range_close()
698 		if (file) {  in __range_close()
700 			filp_close(file, files);  in __range_close()
713  * __close_range() - Close all file descriptors in a given range.
715  * @fd:     starting file descriptor to close
716  * @max_fd: last file descriptor to close
719  * This closes a range of file descriptors. All file descriptors
738 		 * copy all of the file descriptors since they still want to  in __close_range()
748 		 * We used to share our file descriptor table, and have now  in __close_range()
762 		 * the new file descriptor table and drop the old one.  in __close_range()
777 struct file *__close_fd_get_file(unsigned int fd)  in __close_fd_get_file()
783  * variant of close_fd that gets a ref on the file for later fput.
784  * The caller must ensure that filp_close() called on the file.
786 struct file *close_fd_get_file(unsigned int fd)  in close_fd_get_file()
789 	struct file *file;  in close_fd_get_file()  local
792 	file = pick_file(files, fd);  in close_fd_get_file()
795 	return file;  in close_fd_get_file()
816 			struct file *file;  in do_close_on_exec()  local
819 			file = fdt->fd[fd];  in do_close_on_exec()
820 			if (!file)  in do_close_on_exec()
825 			filp_close(file, files);  in do_close_on_exec()
834 static inline struct file *__fget_files_rcu(struct files_struct *files,  in __fget_files_rcu()
838 		struct file *file;  in __fget_files_rcu()  local
840 		struct file __rcu **fdentry;  in __fget_files_rcu()
846 		file = rcu_dereference_raw(*fdentry);  in __fget_files_rcu()
847 		if (unlikely(!file))  in __fget_files_rcu()
850 		if (unlikely(file->f_mode & mask))  in __fget_files_rcu()
854 		 * Ok, we have a file pointer. However, because we do  in __fget_files_rcu()
856 		 * that file being closed.  in __fget_files_rcu()
860 		 *  (a) the file ref already went down to zero,  in __fget_files_rcu()
863 		if (unlikely(!get_file_rcu(file)))  in __fget_files_rcu()
867 		 *  (b) the file table entry has changed under us.  in __fget_files_rcu()
875 		    unlikely(rcu_dereference_raw(*fdentry) != file)) {  in __fget_files_rcu()
876 			fput(file);  in __fget_files_rcu()
881 		 * Ok, we have a ref to the file, and checked that it  in __fget_files_rcu()
884 		return file;  in __fget_files_rcu()
888 static struct file *__fget_files(struct files_struct *files, unsigned int fd,  in __fget_files()
891 	struct file *file;  in __fget_files()  local
894 	file = __fget_files_rcu(files, fd, mask);  in __fget_files()
897 	return file;  in __fget_files()
900 static inline struct file *__fget(unsigned int fd, fmode_t mask)  in __fget()
905 struct file *fget(unsigned int fd)  in fget()
911 struct file *fget_raw(unsigned int fd)  in fget_raw()
917 struct file *fget_task(struct task_struct *task, unsigned int fd)  in fget_task()
919 	struct file *file = NULL;  in fget_task()  local
923 		file = __fget_files(task->files, fd, 0);  in fget_task()
926 	return file;  in fget_task()
929 struct file *task_lookup_fd_rcu(struct task_struct *task, unsigned int fd)  in task_lookup_fd_rcu()
933 	struct file *file = NULL;  in task_lookup_fd_rcu()  local
938 		file = files_lookup_fd_rcu(files, fd);  in task_lookup_fd_rcu()
941 	return file;  in task_lookup_fd_rcu()
944 struct file *task_lookup_next_fd_rcu(struct task_struct *task, unsigned int *ret_fd)  in task_lookup_next_fd_rcu()
949 	struct file *file = NULL;  in task_lookup_next_fd_rcu()  local
955 			file = files_lookup_fd_rcu(files, fd);  in task_lookup_next_fd_rcu()
956 			if (file)  in task_lookup_next_fd_rcu()
962 	return file;  in task_lookup_next_fd_rcu()
967  * Lightweight file lookup - no refcnt increment if fd table isn't shared.
972  *    to userspace (i.e. you cannot remember the returned struct file * after
974  * 2) You must not call filp_close on the returned struct file * in between
985 	struct file *file;  in __fget_light()  local
991 	 * return a file that is concurrently being freed.  in __fget_light()
997 		file = files_lookup_fd_raw(files, fd);  in __fget_light()
998 		if (!file || unlikely(file->f_mode & mask))  in __fget_light()
1000 		return (unsigned long)file;  in __fget_light()
1002 		file = __fget(fd, mask);  in __fget_light()
1003 		if (!file)  in __fget_light()
1005 		return FDPUT_FPUT | (unsigned long)file;  in __fget_light()
1021  * file is marked for FMODE_ATOMIC_POS, and it can be
1025  * can make a file accessible even if it otherwise would
1029 static inline bool file_needs_f_pos_lock(struct file *file)  in file_needs_f_pos_lock()  argument
1031 	return (file->f_mode & FMODE_ATOMIC_POS) &&  in file_needs_f_pos_lock()
1032 		(file_count(file) > 1 || file->f_op->iterate_shared);  in file_needs_f_pos_lock()
1038 	struct file *file = (struct file *)(v & ~3);  in __fdget_pos()  local
1040 	if (file && file_needs_f_pos_lock(file)) {  in __fdget_pos()
1042 		mutex_lock(&file->f_pos_lock);  in __fdget_pos()
1047 void __f_unlock_pos(struct file *f)  in __f_unlock_pos()
1053  * We only lock f_pos if we have threads or if the file might be
1055  * file count (done either by fdget() or by fork()).
1084 	struct file *file, unsigned fd, unsigned flags)  in do_dup2()  argument
1087 	struct file *tofree;  in do_dup2()
1094 	 * file immediately after grabbing descriptor, mark it larval if  in do_dup2()
1109 	get_file(file);  in do_dup2()
1110 	rcu_assign_pointer(fdt->fd[fd], file);  in do_dup2()
1128 int replace_fd(unsigned fd, struct file *file, unsigned flags)  in replace_fd()  argument
1133 	if (!file)  in replace_fd()
1143 	return do_dup2(files, file, fd, flags);  in replace_fd()
1151  * __receive_fd() - Install received file into file descriptor table
1152  * @file: struct file that was received from another process
1156  * Installs a received file into the file descriptor table, with appropriate
1161  * struct file.
1165 int __receive_fd(struct file *file, int __user *ufd, unsigned int o_flags)  in __receive_fd()  argument
1170 	error = security_file_receive(file);  in __receive_fd()
1186 	fd_install(new_fd, get_file(file));  in __receive_fd()
1187 	__receive_sock(file);  in __receive_fd()
1191 int receive_fd_replace(int new_fd, struct file *file, unsigned int o_flags)  in receive_fd_replace()  argument
1195 	error = security_file_receive(file);  in receive_fd_replace()
1198 	error = replace_fd(new_fd, file, o_flags);  in receive_fd_replace()
1201 	__receive_sock(file);  in receive_fd_replace()
1205 int receive_fd(struct file *file, unsigned int o_flags)  in receive_fd()  argument
1207 	return __receive_fd(file, NULL, o_flags);  in receive_fd()
1214 	struct file *file;  in ksys_dup3()  local
1228 	file = files_lookup_fd_locked(files, oldfd);  in ksys_dup3()
1229 	if (unlikely(!file))  in ksys_dup3()
1236 	return do_dup2(files, file, newfd, flags);  in ksys_dup3()
1268 	struct file *file = fget_raw(fildes);  in SYSCALL_DEFINE1()  local
1270 	if (file) {  in SYSCALL_DEFINE1()
1273 			fd_install(ret, file);  in SYSCALL_DEFINE1()
1275 			fput(file);  in SYSCALL_DEFINE1()
1280 int f_dupfd(unsigned int from, struct file *file, unsigned flags)  in f_dupfd()  argument
1288 		get_file(file);  in f_dupfd()
1289 		fd_install(err, file);  in f_dupfd()
1295 		int (*f)(const void *, struct file *, unsigned),  in iterate_fd()  argument
1304 		struct file *file;  in iterate_fd()  local
1305 		file = rcu_dereference_check_fdtable(files, fdt->fd[n]);  in iterate_fd()
1306 		if (!file)  in iterate_fd()
1308 		res = f(p, file, n);  in iterate_fd()