3  *  linux/fs/file.c
17 #include <linux/file.h>
51  * space if any.  This does not copy the file pointers.  Called with the files
73  * Copy all file descriptors from the old table to the new, expanded table and
82 	cpy = ofdt->max_fds * sizeof(struct file *);  in copy_fdtable()
83 	set = (nfdt->max_fds - ofdt->max_fds) * sizeof(struct file *);  in copy_fdtable()
117 	nr /= (1024 / sizeof(struct file *));  in alloc_fdtable()
119 	nr *= (1024 / sizeof(struct file *));  in alloc_fdtable()
136 	data = kvmalloc_array(nr, sizeof(struct file *), GFP_KERNEL_ACCOUNT);  in alloc_fdtable()
163  * Expand the file descriptor table.
208  * This function will expand the file structures, if the requested size exceeds
319 	struct file **old_fds, **new_fds;  in dup_fd()
383 		struct file *f = *old_fds++;  in dup_fd()
400 	memset(new_fds, 0, (new_fdt->max_fds - open_files) * sizeof(struct file *));  in dup_fd()
430 				struct file * file = xchg(&fdt->fd[i], NULL);  in close_files()  local
431 				if (file) {  in close_files()
432 					filp_close(file, files);  in close_files()
497  * allocate a file descriptor, mark it busy.
587  * Install a file pointer in the fd array.
590  * setting the open_fds bitmap and installing the file in the file
592  * installing a file in the array before us.  We need to detect this and
593  * fput() the struct file we are about to overwrite in this case.
598  * This consumes the "file" refcount, so callers should treat it
599  * as if they had called fput(file).
602 void fd_install(unsigned int fd, struct file *file)  in fd_install()  argument
614 		rcu_assign_pointer(fdt->fd[fd], file);  in fd_install()
622 	rcu_assign_pointer(fdt->fd[fd], file);  in fd_install()
629  * pick_file - return file associatd with fd
630  * @files: file struct to retrieve file from
631  * @fd: file descriptor to retrieve file for
635  * Returns: The file associated with @fd (NULL if @fd is not open)
637 static struct file *pick_file(struct files_struct *files, unsigned fd)  in pick_file()
640 	struct file *file;  in pick_file()  local
645 	file = fdt->fd[fd];  in pick_file()
646 	if (file) {  in pick_file()
650 	return file;  in pick_file()
656 	struct file *file;  in close_fd()  local
659 	file = pick_file(files, fd);  in close_fd()
661 	if (!file)  in close_fd()
664 	return filp_close(file, files);  in close_fd()
706 		struct file *file;  in __range_close()  local
709 		file = pick_file(cur_fds, fd++);  in __range_close()
712 		if (file) {  in __range_close()
713 			/* found a valid file to close */  in __range_close()
714 			filp_close(file, cur_fds);  in __range_close()
721  * __close_range() - Close all file descriptors in a given range.
723  * @fd:     starting file descriptor to close
724  * @max_fd: last file descriptor to close
726  * This closes a range of file descriptors. All file descriptors
746 		 * copy all of the file descriptors since they still want to  in __close_range()
753 			 * file descriptors beneath the lowest file descriptor.  in __close_range()
766 		 * We used to share our file descriptor table, and have now  in __close_range()
781 		 * the new file descriptor table and drop the old one.  in __close_range()
796 struct file *__close_fd_get_file(unsigned int fd)  in __close_fd_get_file()
802  * variant of close_fd that gets a ref on the file for later fput.
803  * The caller must ensure that filp_close() called on the file.
805 struct file *close_fd_get_file(unsigned int fd)  in close_fd_get_file()
808 	struct file *file;  in close_fd_get_file()  local
811 	file = pick_file(files, fd);  in close_fd_get_file()
814 	return file;  in close_fd_get_file()
835 			struct file *file;  in do_close_on_exec()  local
838 			file = fdt->fd[fd];  in do_close_on_exec()
839 			if (!file)  in do_close_on_exec()
844 			filp_close(file, files);  in do_close_on_exec()
853 static inline struct file *__fget_files_rcu(struct files_struct *files,  in __fget_files_rcu()
857 		struct file *file;  in __fget_files_rcu()  local
859 		struct file __rcu **fdentry;  in __fget_files_rcu()
865 		file = rcu_dereference_raw(*fdentry);  in __fget_files_rcu()
866 		if (unlikely(!file))  in __fget_files_rcu()
869 		if (unlikely(file->f_mode & mask))  in __fget_files_rcu()
873 		 * Ok, we have a file pointer. However, because we do  in __fget_files_rcu()
875 		 * that file being closed.  in __fget_files_rcu()
879 		 *  (a) the file ref already went down to zero,  in __fget_files_rcu()
882 		if (unlikely(!get_file_rcu(file)))  in __fget_files_rcu()
886 		 *  (b) the file table entry has changed under us.  in __fget_files_rcu()
894 		    unlikely(rcu_dereference_raw(*fdentry) != file)) {  in __fget_files_rcu()
895 			fput(file);  in __fget_files_rcu()
900 		 * Ok, we have a ref to the file, and checked that it  in __fget_files_rcu()
903 		return file;  in __fget_files_rcu()
907 static struct file *__fget_files(struct files_struct *files, unsigned int fd,  in __fget_files()
910 	struct file *file;  in __fget_files()  local
913 	file = __fget_files_rcu(files, fd, mask);  in __fget_files()
916 	return file;  in __fget_files()
919 static inline struct file *__fget(unsigned int fd, fmode_t mask)  in __fget()
924 struct file *fget(unsigned int fd)  in fget()
930 struct file *fget_raw(unsigned int fd)  in fget_raw()
936 struct file *fget_task(struct task_struct *task, unsigned int fd)  in fget_task()
938 	struct file *file = NULL;  in fget_task()  local
942 		file = __fget_files(task->files, fd, 0);  in fget_task()
945 	return file;  in fget_task()
948 struct file *task_lookup_fd_rcu(struct task_struct *task, unsigned int fd)  in task_lookup_fd_rcu()
952 	struct file *file = NULL;  in task_lookup_fd_rcu()  local
957 		file = files_lookup_fd_rcu(files, fd);  in task_lookup_fd_rcu()
960 	return file;  in task_lookup_fd_rcu()
963 struct file *task_lookup_next_fd_rcu(struct task_struct *task, unsigned int *ret_fd)  in task_lookup_next_fd_rcu()
968 	struct file *file = NULL;  in task_lookup_next_fd_rcu()  local
974 			file = files_lookup_fd_rcu(files, fd);  in task_lookup_next_fd_rcu()
975 			if (file)  in task_lookup_next_fd_rcu()
981 	return file;  in task_lookup_next_fd_rcu()
986  * Lightweight file lookup - no refcnt increment if fd table isn't shared.
991  *    to userspace (i.e. you cannot remember the returned struct file * after
993  * 2) You must not call filp_close on the returned struct file * in between
1004 	struct file *file;  in __fget_light()  local
1010 	 * return a file that is concurrently being freed.  in __fget_light()
1016 		file = files_lookup_fd_raw(files, fd);  in __fget_light()
1017 		if (!file || unlikely(file->f_mode & mask))  in __fget_light()
1019 		return (unsigned long)file;  in __fget_light()
1021 		file = __fget(fd, mask);  in __fget_light()
1022 		if (!file)  in __fget_light()
1024 		return FDPUT_FPUT | (unsigned long)file;  in __fget_light()
1041 	struct file *file = (struct file *)(v & ~3);  in __fdget_pos()  local
1043 	if (file && (file->f_mode & FMODE_ATOMIC_POS)) {  in __fdget_pos()
1044 		if (file_count(file) > 1) {  in __fdget_pos()
1046 			mutex_lock(&file->f_pos_lock);  in __fdget_pos()
1052 void __f_unlock_pos(struct file *f)  in __f_unlock_pos()
1058  * We only lock f_pos if we have threads or if the file might be
1060  * file count (done either by fdget() or by fork()).
1089 	struct file *file, unsigned fd, unsigned flags)  in do_dup2()  argument
1092 	struct file *tofree;  in do_dup2()
1099 	 * file immediately after grabbing descriptor, mark it larval if  in do_dup2()
1113 	get_file(file);  in do_dup2()
1114 	rcu_assign_pointer(fdt->fd[fd], file);  in do_dup2()
1132 int replace_fd(unsigned fd, struct file *file, unsigned flags)  in replace_fd()  argument
1137 	if (!file)  in replace_fd()
1147 	return do_dup2(files, file, fd, flags);  in replace_fd()
1155  * __receive_fd() - Install received file into file descriptor table
1156  * @file: struct file that was received from another process
1160  * Installs a received file into the file descriptor table, with appropriate
1165  * struct file.
1169 int __receive_fd(struct file *file, int __user *ufd, unsigned int o_flags)  in __receive_fd()  argument
1174 	error = security_file_receive(file);  in __receive_fd()
1190 	fd_install(new_fd, get_file(file));  in __receive_fd()
1191 	__receive_sock(file);  in __receive_fd()
1195 int receive_fd_replace(int new_fd, struct file *file, unsigned int o_flags)  in receive_fd_replace()  argument
1199 	error = security_file_receive(file);  in receive_fd_replace()
1202 	error = replace_fd(new_fd, file, o_flags);  in receive_fd_replace()
1205 	__receive_sock(file);  in receive_fd_replace()
1209 int receive_fd(struct file *file, unsigned int o_flags)  in receive_fd()  argument
1211 	return __receive_fd(file, NULL, o_flags);  in receive_fd()
1218 	struct file *file;  in ksys_dup3()  local
1232 	file = files_lookup_fd_locked(files, oldfd);  in ksys_dup3()
1233 	if (unlikely(!file))  in ksys_dup3()
1240 	return do_dup2(files, file, newfd, flags);  in ksys_dup3()
1272 	struct file *file = fget_raw(fildes);  in SYSCALL_DEFINE1()  local
1274 	if (file) {  in SYSCALL_DEFINE1()
1277 			fd_install(ret, file);  in SYSCALL_DEFINE1()
1279 			fput(file);  in SYSCALL_DEFINE1()
1284 int f_dupfd(unsigned int from, struct file *file, unsigned flags)  in f_dupfd()  argument
1292 		get_file(file);  in f_dupfd()
1293 		fd_install(err, file);  in f_dupfd()
1299 		int (*f)(const void *, struct file *, unsigned),  in iterate_fd()  argument
1308 		struct file *file;  in iterate_fd()  local
1309 		file = rcu_dereference_check_fdtable(files, fdt->fd[n]);  in iterate_fd()
1310 		if (!file)  in iterate_fd()
1312 		res = f(p, file, n);  in iterate_fd()