From 9f3acc3140444a900ab280de942291959f0f615d Mon Sep 17 00:00:00 2001
From: Al Viro <viro@zeniv.linux.org.uk>
Date: Thu, 24 Apr 2008 07:44:08 -0400
Subject: [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>
---
 include/linux/fdtable.h | 99 +++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 99 insertions(+)
 create mode 100644 include/linux/fdtable.h

(limited to 'include/linux/fdtable.h')

diff --git a/include/linux/fdtable.h b/include/linux/fdtable.h
new file mode 100644
index 00000000000..a118f3c0b24
--- /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 */
-- 
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