89 lines
1.6 KiB
C
89 lines
1.6 KiB
C
/*
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* linux/fs/file_table.c
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*
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* Copyright (C) 1991, 1992 Linus Torvalds
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*/
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#include <linux/fs.h>
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#include <linux/string.h>
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#include <linux/mm.h>
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struct file * first_file;
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int nr_files = 0;
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static void insert_file_free(struct file *file)
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{
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file->f_next = first_file;
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file->f_prev = first_file->f_prev;
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file->f_next->f_prev = file;
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file->f_prev->f_next = file;
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first_file = file;
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}
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static void remove_file_free(struct file *file)
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{
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if (first_file == file)
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first_file = first_file->f_next;
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if (file->f_next)
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file->f_next->f_prev = file->f_prev;
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if (file->f_prev)
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file->f_prev->f_next = file->f_next;
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file->f_next = file->f_prev = NULL;
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}
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static void put_last_free(struct file *file)
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{
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remove_file_free(file);
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file->f_prev = first_file->f_prev;
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file->f_prev->f_next = file;
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file->f_next = first_file;
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file->f_next->f_prev = file;
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}
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void grow_files(void)
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{
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struct file * file;
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int i;
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file = (struct file *) get_free_page(GFP_KERNEL);
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if (!file)
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return;
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nr_files+=i= PAGE_SIZE/sizeof(struct file);
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if (!first_file)
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file->f_next = file->f_prev = first_file = file++, i--;
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for (; i ; i--)
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insert_file_free(file++);
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}
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unsigned long file_table_init(unsigned long start, unsigned long end)
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{
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first_file = NULL;
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return start;
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}
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struct file * get_empty_filp(void)
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{
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int i;
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struct file * f;
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if (!first_file)
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grow_files();
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repeat:
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for (f = first_file, i=0; i < nr_files; i++, f = f->f_next)
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if (!f->f_count) {
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remove_file_free(f);
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memset(f,0,sizeof(*f));
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put_last_free(f);
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f->f_count = 1;
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return f;
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}
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if (nr_files < NR_FILE) {
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grow_files();
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goto repeat;
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}
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return NULL;
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}
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