1 /* SPDX-License-Identifier: GPL-2.0 */
3 * descriptor table internals; you almost certainly want file.h instead.
6 #ifndef __LINUX_FDTABLE_H
7 #define __LINUX_FDTABLE_H
9 #include <linux/posix_types.h>
10 #include <linux/compiler.h>
11 #include <linux/spinlock.h>
12 #include <linux/rcupdate.h>
13 #include <linux/types.h>
14 #include <linux/init.h>
17 #include <linux/atomic.h>
20 * The default fd array needs to be at least BITS_PER_LONG,
21 * as this is the granularity returned by copy_fdset().
23 #define NR_OPEN_DEFAULT BITS_PER_LONG
27 struct file __rcu **fd; /* current fd array */
28 unsigned long *close_on_exec;
29 unsigned long *open_fds;
30 unsigned long *full_fds_bits;
34 static inline bool close_on_exec(unsigned int fd, const struct fdtable *fdt)
36 return test_bit(fd, fdt->close_on_exec);
39 static inline bool fd_is_open(unsigned int fd, const struct fdtable *fdt)
41 return test_bit(fd, fdt->open_fds);
45 * Open file table structure
52 bool resize_in_progress;
53 wait_queue_head_t resize_wait;
55 struct fdtable __rcu *fdt;
58 * written part on a separate cache line in SMP
60 spinlock_t file_lock ____cacheline_aligned_in_smp;
62 unsigned long close_on_exec_init[1];
63 unsigned long open_fds_init[1];
64 unsigned long full_fds_bits_init[1];
65 struct file __rcu * fd_array[NR_OPEN_DEFAULT];
68 struct file_operations;
72 #define rcu_dereference_check_fdtable(files, fdtfd) \
73 rcu_dereference_check((fdtfd), lockdep_is_held(&(files)->file_lock))
75 #define files_fdtable(files) \
76 rcu_dereference_check_fdtable((files), (files)->fdt)
79 * The caller must ensure that fd table isn't shared or hold rcu or file lock
81 static inline struct file *__fcheck_files(struct files_struct *files, unsigned int fd)
83 struct fdtable *fdt = rcu_dereference_raw(files->fdt);
85 if (fd < fdt->max_fds)
86 return rcu_dereference_raw(fdt->fd[fd]);
90 static inline struct file *fcheck_files(struct files_struct *files, unsigned int fd)
92 RCU_LOCKDEP_WARN(!rcu_read_lock_held() &&
93 !lockdep_is_held(&files->file_lock),
94 "suspicious rcu_dereference_check() usage");
95 return __fcheck_files(files, fd);
99 * Check whether the specified fd has an open file.
101 #define fcheck(fd) fcheck_files(current->files, fd)
105 struct files_struct *get_files_struct(struct task_struct *);
106 void put_files_struct(struct files_struct *fs);
107 void reset_files_struct(struct files_struct *);
108 int unshare_files(struct files_struct **);
109 struct files_struct *dup_fd(struct files_struct *, int *) __latent_entropy;
110 void do_close_on_exec(struct files_struct *);
111 int iterate_fd(struct files_struct *, unsigned,
112 int (*)(const void *, struct file *, unsigned),
115 extern int __alloc_fd(struct files_struct *files,
116 unsigned start, unsigned end, unsigned flags);
117 extern void __fd_install(struct files_struct *files,
118 unsigned int fd, struct file *file);
119 extern int __close_fd(struct files_struct *files,
122 extern struct kmem_cache *files_cachep;
124 #endif /* __LINUX_FDTABLE_H */