[PATCH] split linux/file.h

Initial splitoff of the low-level stuff; taken to fdtable.h

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>

1 files changed, 99 insertions, 0 deletions

diff --git a/include/linux/fdtable.h b/include/linux/fdtable.h
new file mode 100644
index 000000000000..a118f3c0b240
--- /dev/null
+++ b/include/linux/fdtable.h
@@ -0,0 +1,99 @@
+/*
+ * descriptor table internals; you almost certainly want file.h instead.
+ */
+
+#ifndef __LINUX_FDTABLE_H
+#define __LINUX_FDTABLE_H
+
+#include <asm/atomic.h>
+#include <linux/posix_types.h>
+#include <linux/compiler.h>
+#include <linux/spinlock.h>
+#include <linux/rcupdate.h>
+#include <linux/types.h>
+
+/*
+ * The default fd array needs to be at least BITS_PER_LONG,
+ * as this is the granularity returned by copy_fdset().
+ */
+#define NR_OPEN_DEFAULT BITS_PER_LONG
+
+/*
+ * The embedded_fd_set is a small fd_set,
+ * suitable for most tasks (which open <= BITS_PER_LONG files)
+ */
+struct embedded_fd_set {
+        unsigned long fds_bits[1];
+};
+
+struct fdtable {
+        unsigned int max_fds;
+        struct file ** fd;      /* current fd array */
+        fd_set *close_on_exec;
+        fd_set *open_fds;
+        struct rcu_head rcu;
+        struct fdtable *next;
+};
+
+/*
+ * Open file table structure
+ */
+struct files_struct {
+  /*
+   * read mostly part
+   */
+        atomic_t count;
+        struct fdtable *fdt;
+        struct fdtable fdtab;
+  /*
+   * written part on a separate cache line in SMP
+   */
+        spinlock_t file_lock ____cacheline_aligned_in_smp;
+        int next_fd;
+        struct embedded_fd_set close_on_exec_init;
+        struct embedded_fd_set open_fds_init;
+        struct file * fd_array[NR_OPEN_DEFAULT];
+};
+
+#define files_fdtable(files) (rcu_dereference((files)->fdt))
+
+extern struct kmem_cache *filp_cachep;
+
+struct file_operations;
+struct vfsmount;
+struct dentry;
+
+extern int expand_files(struct files_struct *, int nr);
+extern void free_fdtable_rcu(struct rcu_head *rcu);
+extern void __init files_defer_init(void);
+
+static inline void free_fdtable(struct fdtable *fdt)
+{
+        call_rcu(&fdt->rcu, free_fdtable_rcu);
+}
+
+static inline struct file * fcheck_files(struct files_struct *files, unsigned int fd)
+{
+        struct file * file = NULL;
+        struct fdtable *fdt = files_fdtable(files);
+
+        if (fd < fdt->max_fds)
+                file = rcu_dereference(fdt->fd[fd]);
+        return file;
+}
+
+/*
+ * Check whether the specified fd has an open file.
+ */
+#define fcheck(fd)      fcheck_files(current->files, fd)
+
+struct task_struct;
+
+struct files_struct *get_files_struct(struct task_struct *);
+void put_files_struct(struct files_struct *fs);
+void reset_files_struct(struct files_struct *);
+int unshare_files(struct files_struct **);
+
+extern struct kmem_cache *files_cachep;
+
+#endif /* __LINUX_FDTABLE_H */