Al Viro | 9f3acc3 | 2008-04-24 07:44:08 -0400 | [diff] [blame] | 1 | /* |
| 2 | * descriptor table internals; you almost certainly want file.h instead. |
| 3 | */ |
| 4 | |
| 5 | #ifndef __LINUX_FDTABLE_H |
| 6 | #define __LINUX_FDTABLE_H |
| 7 | |
Al Viro | 9f3acc3 | 2008-04-24 07:44:08 -0400 | [diff] [blame] | 8 | #include <linux/posix_types.h> |
| 9 | #include <linux/compiler.h> |
| 10 | #include <linux/spinlock.h> |
| 11 | #include <linux/rcupdate.h> |
| 12 | #include <linux/types.h> |
Ingo Molnar | 21e5445 | 2009-03-25 16:29:05 +0100 | [diff] [blame] | 13 | #include <linux/init.h> |
Paul E. McKenney | 2c666df | 2010-04-29 20:48:47 -0700 | [diff] [blame] | 14 | #include <linux/fs.h> |
Ingo Molnar | 21e5445 | 2009-03-25 16:29:05 +0100 | [diff] [blame] | 15 | |
Arun Sharma | 60063497 | 2011-07-26 16:09:06 -0700 | [diff] [blame] | 16 | #include <linux/atomic.h> |
Al Viro | 9f3acc3 | 2008-04-24 07:44:08 -0400 | [diff] [blame] | 17 | |
| 18 | /* |
| 19 | * The default fd array needs to be at least BITS_PER_LONG, |
| 20 | * as this is the granularity returned by copy_fdset(). |
| 21 | */ |
| 22 | #define NR_OPEN_DEFAULT BITS_PER_LONG |
| 23 | |
| 24 | /* |
| 25 | * The embedded_fd_set is a small fd_set, |
| 26 | * suitable for most tasks (which open <= BITS_PER_LONG files) |
| 27 | */ |
| 28 | struct embedded_fd_set { |
| 29 | unsigned long fds_bits[1]; |
| 30 | }; |
| 31 | |
| 32 | struct fdtable { |
| 33 | unsigned int max_fds; |
Arnd Bergmann | 4d2deb4 | 2010-02-24 20:01:56 +0100 | [diff] [blame] | 34 | struct file __rcu **fd; /* current fd array */ |
Al Viro | 9f3acc3 | 2008-04-24 07:44:08 -0400 | [diff] [blame] | 35 | fd_set *close_on_exec; |
| 36 | fd_set *open_fds; |
| 37 | struct rcu_head rcu; |
| 38 | struct fdtable *next; |
| 39 | }; |
| 40 | |
David Howells | 1dce27c | 2012-02-16 17:49:42 +0000 | [diff] [blame^] | 41 | static inline void __set_close_on_exec(int fd, struct fdtable *fdt) |
| 42 | { |
| 43 | FD_SET(fd, fdt->close_on_exec); |
| 44 | } |
| 45 | |
| 46 | static inline void __clear_close_on_exec(int fd, struct fdtable *fdt) |
| 47 | { |
| 48 | FD_CLR(fd, fdt->close_on_exec); |
| 49 | } |
| 50 | |
| 51 | static inline bool close_on_exec(int fd, const struct fdtable *fdt) |
| 52 | { |
| 53 | return FD_ISSET(fd, fdt->close_on_exec); |
| 54 | } |
| 55 | |
| 56 | static inline void __set_open_fd(int fd, struct fdtable *fdt) |
| 57 | { |
| 58 | FD_SET(fd, fdt->open_fds); |
| 59 | } |
| 60 | |
| 61 | static inline void __clear_open_fd(int fd, struct fdtable *fdt) |
| 62 | { |
| 63 | FD_CLR(fd, fdt->open_fds); |
| 64 | } |
| 65 | |
| 66 | static inline bool fd_is_open(int fd, const struct fdtable *fdt) |
| 67 | { |
| 68 | return FD_ISSET(fd, fdt->open_fds); |
| 69 | } |
| 70 | |
Al Viro | 9f3acc3 | 2008-04-24 07:44:08 -0400 | [diff] [blame] | 71 | /* |
| 72 | * Open file table structure |
| 73 | */ |
| 74 | struct files_struct { |
| 75 | /* |
| 76 | * read mostly part |
| 77 | */ |
| 78 | atomic_t count; |
Arnd Bergmann | 4d2deb4 | 2010-02-24 20:01:56 +0100 | [diff] [blame] | 79 | struct fdtable __rcu *fdt; |
Al Viro | 9f3acc3 | 2008-04-24 07:44:08 -0400 | [diff] [blame] | 80 | struct fdtable fdtab; |
| 81 | /* |
| 82 | * written part on a separate cache line in SMP |
| 83 | */ |
| 84 | spinlock_t file_lock ____cacheline_aligned_in_smp; |
| 85 | int next_fd; |
| 86 | struct embedded_fd_set close_on_exec_init; |
| 87 | struct embedded_fd_set open_fds_init; |
Arnd Bergmann | 4d2deb4 | 2010-02-24 20:01:56 +0100 | [diff] [blame] | 88 | struct file __rcu * fd_array[NR_OPEN_DEFAULT]; |
Al Viro | 9f3acc3 | 2008-04-24 07:44:08 -0400 | [diff] [blame] | 89 | }; |
| 90 | |
Paul E. McKenney | af61b96 | 2010-02-22 17:04:53 -0800 | [diff] [blame] | 91 | #define rcu_dereference_check_fdtable(files, fdtfd) \ |
| 92 | (rcu_dereference_check((fdtfd), \ |
Paul E. McKenney | 7dc5215 | 2010-02-22 17:04:52 -0800 | [diff] [blame] | 93 | lockdep_is_held(&(files)->file_lock) || \ |
Paul E. McKenney | 844b9a8 | 2010-07-20 13:24:34 -0700 | [diff] [blame] | 94 | atomic_read(&(files)->count) == 1 || \ |
| 95 | rcu_my_thread_group_empty())) |
Paul E. McKenney | af61b96 | 2010-02-22 17:04:53 -0800 | [diff] [blame] | 96 | |
| 97 | #define files_fdtable(files) \ |
| 98 | (rcu_dereference_check_fdtable((files), (files)->fdt)) |
Al Viro | 9f3acc3 | 2008-04-24 07:44:08 -0400 | [diff] [blame] | 99 | |
Al Viro | 9f3acc3 | 2008-04-24 07:44:08 -0400 | [diff] [blame] | 100 | struct file_operations; |
| 101 | struct vfsmount; |
| 102 | struct dentry; |
| 103 | |
| 104 | extern int expand_files(struct files_struct *, int nr); |
| 105 | extern void free_fdtable_rcu(struct rcu_head *rcu); |
| 106 | extern void __init files_defer_init(void); |
| 107 | |
| 108 | static inline void free_fdtable(struct fdtable *fdt) |
| 109 | { |
| 110 | call_rcu(&fdt->rcu, free_fdtable_rcu); |
| 111 | } |
| 112 | |
| 113 | static inline struct file * fcheck_files(struct files_struct *files, unsigned int fd) |
| 114 | { |
| 115 | struct file * file = NULL; |
| 116 | struct fdtable *fdt = files_fdtable(files); |
| 117 | |
| 118 | if (fd < fdt->max_fds) |
Paul E. McKenney | af61b96 | 2010-02-22 17:04:53 -0800 | [diff] [blame] | 119 | file = rcu_dereference_check_fdtable(files, fdt->fd[fd]); |
Al Viro | 9f3acc3 | 2008-04-24 07:44:08 -0400 | [diff] [blame] | 120 | return file; |
| 121 | } |
| 122 | |
| 123 | /* |
| 124 | * Check whether the specified fd has an open file. |
| 125 | */ |
| 126 | #define fcheck(fd) fcheck_files(current->files, fd) |
| 127 | |
| 128 | struct task_struct; |
| 129 | |
| 130 | struct files_struct *get_files_struct(struct task_struct *); |
| 131 | void put_files_struct(struct files_struct *fs); |
| 132 | void reset_files_struct(struct files_struct *); |
| 133 | int unshare_files(struct files_struct **); |
Al Viro | 02afc626 | 2008-05-08 19:42:56 -0400 | [diff] [blame] | 134 | struct files_struct *dup_fd(struct files_struct *, int *); |
Al Viro | 9f3acc3 | 2008-04-24 07:44:08 -0400 | [diff] [blame] | 135 | |
| 136 | extern struct kmem_cache *files_cachep; |
| 137 | |
| 138 | #endif /* __LINUX_FDTABLE_H */ |