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
646 	file = fdt->fd[fd];  in pick_file()
647 	if (file) {  in pick_file()
651 	return file;  in pick_file()
657 	struct file *file;  in close_fd()  local
660 	file = pick_file(files, fd);  in close_fd()
662 	if (!file)  in close_fd()
665 	return filp_close(file, files);  in close_fd()
671  * @fdt: File descriptor table.
699 	struct file *file;  in __range_close()  local
707 		file = pick_file(files, fd);  in __range_close()
708 		if (file) {  in __range_close()
710 			filp_close(file, files);  in __range_close()
723  * __close_range() - Close all file descriptors in a given range.
725  * @fd:     starting file descriptor to close
726  * @max_fd: last file descriptor to close
729  * This closes a range of file descriptors. All file descriptors
749 		 * copy all of the file descriptors since they still want to  in __close_range()
756 			 * file descriptors beneath the lowest file descriptor.  in __close_range()
769 		 * We used to share our file descriptor table, and have now  in __close_range()
784 		 * the new file descriptor table and drop the old one.  in __close_range()
799 struct file *__close_fd_get_file(unsigned int fd)  in __close_fd_get_file()
805  * variant of close_fd that gets a ref on the file for later fput.
806  * The caller must ensure that filp_close() called on the file.
808 struct file *close_fd_get_file(unsigned int fd)  in close_fd_get_file()
811 	struct file *file;  in close_fd_get_file()  local
814 	file = pick_file(files, fd);  in close_fd_get_file()
817 	return file;  in close_fd_get_file()
838 			struct file *file;  in do_close_on_exec()  local
841 			file = fdt->fd[fd];  in do_close_on_exec()
842 			if (!file)  in do_close_on_exec()
847 			filp_close(file, files);  in do_close_on_exec()
856 static inline struct file *__fget_files_rcu(struct files_struct *files,  in __fget_files_rcu()
860 		struct file *file;  in __fget_files_rcu()  local
862 		struct file __rcu **fdentry;  in __fget_files_rcu()
868 		file = rcu_dereference_raw(*fdentry);  in __fget_files_rcu()
869 		if (unlikely(!file))  in __fget_files_rcu()
872 		if (unlikely(file->f_mode & mask))  in __fget_files_rcu()
876 		 * Ok, we have a file pointer. However, because we do  in __fget_files_rcu()
878 		 * that file being closed.  in __fget_files_rcu()
882 		 *  (a) the file ref already went down to zero,  in __fget_files_rcu()
885 		if (unlikely(!get_file_rcu(file)))  in __fget_files_rcu()
889 		 *  (b) the file table entry has changed under us.  in __fget_files_rcu()
897 		    unlikely(rcu_dereference_raw(*fdentry) != file)) {  in __fget_files_rcu()
898 			fput(file);  in __fget_files_rcu()
903 		 * Ok, we have a ref to the file, and checked that it  in __fget_files_rcu()
906 		return file;  in __fget_files_rcu()
910 static struct file *__fget_files(struct files_struct *files, unsigned int fd,  in __fget_files()
913 	struct file *file;  in __fget_files()  local
916 	file = __fget_files_rcu(files, fd, mask);  in __fget_files()
919 	return file;  in __fget_files()
922 static inline struct file *__fget(unsigned int fd, fmode_t mask)  in __fget()
927 struct file *fget(unsigned int fd)  in fget()
933 struct file *fget_raw(unsigned int fd)  in fget_raw()
939 struct file *fget_task(struct task_struct *task, unsigned int fd)  in fget_task()
941 	struct file *file = NULL;  in fget_task()  local
945 		file = __fget_files(task->files, fd, 0);  in fget_task()
948 	return file;  in fget_task()
951 struct file *task_lookup_fd_rcu(struct task_struct *task, unsigned int fd)  in task_lookup_fd_rcu()
955 	struct file *file = NULL;  in task_lookup_fd_rcu()  local
960 		file = files_lookup_fd_rcu(files, fd);  in task_lookup_fd_rcu()
963 	return file;  in task_lookup_fd_rcu()
966 struct file *task_lookup_next_fd_rcu(struct task_struct *task, unsigned int *ret_fd)  in task_lookup_next_fd_rcu()
971 	struct file *file = NULL;  in task_lookup_next_fd_rcu()  local
977 			file = files_lookup_fd_rcu(files, fd);  in task_lookup_next_fd_rcu()
978 			if (file)  in task_lookup_next_fd_rcu()
984 	return file;  in task_lookup_next_fd_rcu()
989  * Lightweight file lookup - no refcnt increment if fd table isn't shared.
994  *    to userspace (i.e. you cannot remember the returned struct file * after
996  * 2) You must not call filp_close on the returned struct file * in between
1007 	struct file *file;  in __fget_light()  local
1013 	 * return a file that is concurrently being freed.  in __fget_light()
1019 		file = files_lookup_fd_raw(files, fd);  in __fget_light()
1020 		if (!file || unlikely(file->f_mode & mask))  in __fget_light()
1022 		return (unsigned long)file;  in __fget_light()
1024 		file = __fget(fd, mask);  in __fget_light()
1025 		if (!file)  in __fget_light()
1027 		return FDPUT_FPUT | (unsigned long)file;  in __fget_light()
1043  * file is marked for FMODE_ATOMIC_POS, and it can be
1047  * can make a file accessible even if it otherwise would
1051 static inline bool file_needs_f_pos_lock(struct file *file)  in file_needs_f_pos_lock()  argument
1053 	return (file->f_mode & FMODE_ATOMIC_POS) &&  in file_needs_f_pos_lock()
1054 		(file_count(file) > 1 || file->f_op->iterate_shared);  in file_needs_f_pos_lock()
1060 	struct file *file = (struct file *)(v & ~3);  in __fdget_pos()  local
1062 	if (file && file_needs_f_pos_lock(file)) {  in __fdget_pos()
1064 		mutex_lock(&file->f_pos_lock);  in __fdget_pos()
1069 void __f_unlock_pos(struct file *f)  in __f_unlock_pos()
1075  * We only lock f_pos if we have threads or if the file might be
1077  * file count (done either by fdget() or by fork()).
1106 	struct file *file, unsigned fd, unsigned flags)  in do_dup2()  argument
1109 	struct file *tofree;  in do_dup2()
1116 	 * file immediately after grabbing descriptor, mark it larval if  in do_dup2()
1130 	get_file(file);  in do_dup2()
1131 	rcu_assign_pointer(fdt->fd[fd], file);  in do_dup2()
1149 int replace_fd(unsigned fd, struct file *file, unsigned flags)  in replace_fd()  argument
1154 	if (!file)  in replace_fd()
1164 	return do_dup2(files, file, fd, flags);  in replace_fd()
1172  * __receive_fd() - Install received file into file descriptor table
1173  * @file: struct file that was received from another process
1177  * Installs a received file into the file descriptor table, with appropriate
1182  * struct file.
1186 int __receive_fd(struct file *file, int __user *ufd, unsigned int o_flags)  in __receive_fd()  argument
1191 	error = security_file_receive(file);  in __receive_fd()
1207 	fd_install(new_fd, get_file(file));  in __receive_fd()
1208 	__receive_sock(file);  in __receive_fd()
1212 int receive_fd_replace(int new_fd, struct file *file, unsigned int o_flags)  in receive_fd_replace()  argument
1216 	error = security_file_receive(file);  in receive_fd_replace()
1219 	error = replace_fd(new_fd, file, o_flags);  in receive_fd_replace()
1222 	__receive_sock(file);  in receive_fd_replace()
1226 int receive_fd(struct file *file, unsigned int o_flags)  in receive_fd()  argument
1228 	return __receive_fd(file, NULL, o_flags);  in receive_fd()
1235 	struct file *file;  in ksys_dup3()  local
1249 	file = files_lookup_fd_locked(files, oldfd);  in ksys_dup3()
1250 	if (unlikely(!file))  in ksys_dup3()
1257 	return do_dup2(files, file, newfd, flags);  in ksys_dup3()
1289 	struct file *file = fget_raw(fildes);  in SYSCALL_DEFINE1()  local
1291 	if (file) {  in SYSCALL_DEFINE1()
1294 			fd_install(ret, file);  in SYSCALL_DEFINE1()
1296 			fput(file);  in SYSCALL_DEFINE1()
1301 int f_dupfd(unsigned int from, struct file *file, unsigned flags)  in f_dupfd()  argument
1309 		get_file(file);  in f_dupfd()
1310 		fd_install(err, file);  in f_dupfd()
1316 		int (*f)(const void *, struct file *, unsigned),  in iterate_fd()  argument
1325 		struct file *file;  in iterate_fd()  local
1326 		file = rcu_dereference_check_fdtable(files, fdt->fd[n]);  in iterate_fd()
1327 		if (!file)  in iterate_fd()
1329 		res = f(p, file, n);  in iterate_fd()