1 files changed, 255 insertions, 0 deletions

diff --git a/fs/file_table.c b/fs/file_table.c
new file mode 100644
index 000000000000..03d83cb686b1
--- /dev/null
+++ b/fs/file_table.c
@@ -0,0 +1,255 @@
+/*
+ *  linux/fs/file_table.c
+ *
+ *  Copyright (C) 1991, 1992  Linus Torvalds
+ *  Copyright (C) 1997 David S. Miller (davem@caip.rutgers.edu)
+ */
+
+#include <linux/string.h>
+#include <linux/slab.h>
+#include <linux/file.h>
+#include <linux/init.h>
+#include <linux/module.h>
+#include <linux/smp_lock.h>
+#include <linux/fs.h>
+#include <linux/security.h>
+#include <linux/eventpoll.h>
+#include <linux/mount.h>
+#include <linux/cdev.h>
+
+/* sysctl tunables... */
+struct files_stat_struct files_stat = {
+        .max_files = NR_FILE
+};
+
+EXPORT_SYMBOL(files_stat); /* Needed by unix.o */
+
+/* public. Not pretty! */
+ __cacheline_aligned_in_smp DEFINE_SPINLOCK(files_lock);
+
+static DEFINE_SPINLOCK(filp_count_lock);
+
+/* slab constructors and destructors are called from arbitrary
+ * context and must be fully threaded - use a local spinlock
+ * to protect files_stat.nr_files
+ */
+void filp_ctor(void * objp, struct kmem_cache_s *cachep, unsigned long cflags)
+{
+        if ((cflags & (SLAB_CTOR_VERIFY|SLAB_CTOR_CONSTRUCTOR)) ==
+            SLAB_CTOR_CONSTRUCTOR) {
+                unsigned long flags;
+                spin_lock_irqsave(&filp_count_lock, flags);
+                files_stat.nr_files++;
+                spin_unlock_irqrestore(&filp_count_lock, flags);
+        }
+}
+
+void filp_dtor(void * objp, struct kmem_cache_s *cachep, unsigned long dflags)
+{
+        unsigned long flags;
+        spin_lock_irqsave(&filp_count_lock, flags);
+        files_stat.nr_files--;
+        spin_unlock_irqrestore(&filp_count_lock, flags);
+}
+
+static inline void file_free(struct file *f)
+{
+        kmem_cache_free(filp_cachep, f);
+}
+
+/* Find an unused file structure and return a pointer to it.
+ * Returns NULL, if there are no more free file structures or
+ * we run out of memory.
+ */
+struct file *get_empty_filp(void)
+{
+static int old_max;
+        struct file * f;
+
+        /*
+         * Privileged users can go above max_files
+         */
+        if (files_stat.nr_files < files_stat.max_files ||
+                                capable(CAP_SYS_ADMIN)) {
+                f = kmem_cache_alloc(filp_cachep, GFP_KERNEL);
+                if (f) {
+                        memset(f, 0, sizeof(*f));
+                        if (security_file_alloc(f)) {
+                                file_free(f);
+                                goto fail;
+                        }
+                        eventpoll_init_file(f);
+                        atomic_set(&f->f_count, 1);
+                        f->f_uid = current->fsuid;
+                        f->f_gid = current->fsgid;
+                        rwlock_init(&f->f_owner.lock);
+                        /* f->f_version: 0 */
+                        INIT_LIST_HEAD(&f->f_list);
+                        f->f_maxcount = INT_MAX;
+                        return f;
+                }
+        }
+
+        /* Ran out of filps - report that */
+        if (files_stat.max_files >= old_max) {
+                printk(KERN_INFO "VFS: file-max limit %d reached\n",
+                                        files_stat.max_files);
+                old_max = files_stat.max_files;
+        } else {
+                /* Big problems... */
+                printk(KERN_WARNING "VFS: filp allocation failed\n");
+        }
+fail:
+        return NULL;
+}
+
+EXPORT_SYMBOL(get_empty_filp);
+
+void fastcall fput(struct file *file)
+{
+        if (atomic_dec_and_test(&file->f_count))
+                __fput(file);
+}
+
+EXPORT_SYMBOL(fput);
+
+/* __fput is called from task context when aio completion releases the last
+ * last use of a struct file *.  Do not use otherwise.
+ */
+void fastcall __fput(struct file *file)
+{
+        struct dentry *dentry = file->f_dentry;
+        struct vfsmount *mnt = file->f_vfsmnt;
+        struct inode *inode = dentry->d_inode;
+
+        might_sleep();
+        /*
+         * The function eventpoll_release() should be the first called
+         * in the file cleanup chain.
+         */
+        eventpoll_release(file);
+        locks_remove_flock(file);
+
+        if (file->f_op && file->f_op->release)
+                file->f_op->release(inode, file);
+        security_file_free(file);
+        if (unlikely(inode->i_cdev != NULL))
+                cdev_put(inode->i_cdev);
+        fops_put(file->f_op);
+        if (file->f_mode & FMODE_WRITE)
+                put_write_access(inode);
+        file_kill(file);
+        file->f_dentry = NULL;
+        file->f_vfsmnt = NULL;
+        file_free(file);
+        dput(dentry);
+        mntput(mnt);
+}
+
+struct file fastcall *fget(unsigned int fd)
+{
+        struct file *file;
+        struct files_struct *files = current->files;
+
+        spin_lock(&files->file_lock);
+        file = fcheck_files(files, fd);
+        if (file)
+                get_file(file);
+        spin_unlock(&files->file_lock);
+        return file;
+}
+
+EXPORT_SYMBOL(fget);
+
+/*
+ * Lightweight file lookup - no refcnt increment if fd table isn't shared. 
+ * You can use this only if it is guranteed that the current task already 
+ * holds a refcnt to that file. That check has to be done at fget() only
+ * and a flag is returned to be passed to the corresponding fput_light().
+ * There must not be a cloning between an fget_light/fput_light pair.
+ */
+struct file fastcall *fget_light(unsigned int fd, int *fput_needed)
+{
+        struct file *file;
+        struct files_struct *files = current->files;
+
+        *fput_needed = 0;
+        if (likely((atomic_read(&files->count) == 1))) {
+                file = fcheck_files(files, fd);
+        } else {
+                spin_lock(&files->file_lock);
+                file = fcheck_files(files, fd);
+                if (file) {
+                        get_file(file);
+                        *fput_needed = 1;
+                }
+                spin_unlock(&files->file_lock);
+        }
+        return file;
+}
+
+
+void put_filp(struct file *file)
+{
+        if (atomic_dec_and_test(&file->f_count)) {
+                security_file_free(file);
+                file_kill(file);
+                file_free(file);
+        }
+}
+
+void file_move(struct file *file, struct list_head *list)
+{
+        if (!list)
+                return;
+        file_list_lock();
+        list_move(&file->f_list, list);
+        file_list_unlock();
+}
+
+void file_kill(struct file *file)
+{
+        if (!list_empty(&file->f_list)) {
+                file_list_lock();
+                list_del_init(&file->f_list);
+                file_list_unlock();
+        }
+}
+
+int fs_may_remount_ro(struct super_block *sb)
+{
+        struct list_head *p;
+
+        /* Check that no files are currently opened for writing. */
+        file_list_lock();
+        list_for_each(p, &sb->s_files) {
+                struct file *file = list_entry(p, struct file, f_list);
+                struct inode *inode = file->f_dentry->d_inode;
+
+                /* File with pending delete? */
+                if (inode->i_nlink == 0)
+                        goto too_bad;
+
+                /* Writeable file? */
+                if (S_ISREG(inode->i_mode) && (file->f_mode & FMODE_WRITE))
+                        goto too_bad;
+        }
+        file_list_unlock();
+        return 1; /* Tis' cool bro. */
+too_bad:
+        file_list_unlock();
+        return 0;
+}
+
+void __init files_init(unsigned long mempages)
+{ 
+        int n; 
+        /* One file with associated inode and dcache is very roughly 1K. 
+         * Per default don't use more than 10% of our memory for files. 
+         */ 
+
+        n = (mempages * (PAGE_SIZE / 1024)) / 10;
+        files_stat.max_files = n; 
+        if (files_stat.max_files < NR_FILE)
+                files_stat.max_files = NR_FILE;
+}