linux/mm/fadvise.c
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   1/*
   2 * mm/fadvise.c
   3 *
   4 * Copyright (C) 2002, Linus Torvalds
   5 *
   6 * 11Jan2003    Andrew Morton
   7 *              Initial version.
   8 */
   9
  10#include <linux/kernel.h>
  11#include <linux/file.h>
  12#include <linux/fs.h>
  13#include <linux/mm.h>
  14#include <linux/pagemap.h>
  15#include <linux/backing-dev.h>
  16#include <linux/pagevec.h>
  17#include <linux/fadvise.h>
  18#include <linux/writeback.h>
  19#include <linux/syscalls.h>
  20
  21#include <asm/unistd.h>
  22
  23/*
  24 * POSIX_FADV_WILLNEED could set PG_Referenced, and POSIX_FADV_NOREUSE could
  25 * deactivate the pages and clear PG_Referenced.
  26 */
  27SYSCALL_DEFINE(fadvise64_64)(int fd, loff_t offset, loff_t len, int advice)
  28{
  29        struct file *file = fget(fd);
  30        struct address_space *mapping;
  31        struct backing_dev_info *bdi;
  32        loff_t endbyte;                 /* inclusive */
  33        pgoff_t start_index;
  34        pgoff_t end_index;
  35        unsigned long nrpages;
  36        int ret = 0;
  37
  38        if (!file)
  39                return -EBADF;
  40
  41        if (S_ISFIFO(file->f_path.dentry->d_inode->i_mode)) {
  42                ret = -ESPIPE;
  43                goto out;
  44        }
  45
  46        mapping = file->f_mapping;
  47        if (!mapping || len < 0) {
  48                ret = -EINVAL;
  49                goto out;
  50        }
  51
  52        if (mapping->a_ops->get_xip_mem) {
  53                switch (advice) {
  54                case POSIX_FADV_NORMAL:
  55                case POSIX_FADV_RANDOM:
  56                case POSIX_FADV_SEQUENTIAL:
  57                case POSIX_FADV_WILLNEED:
  58                case POSIX_FADV_NOREUSE:
  59                case POSIX_FADV_DONTNEED:
  60                        /* no bad return value, but ignore advice */
  61                        break;
  62                default:
  63                        ret = -EINVAL;
  64                }
  65                goto out;
  66        }
  67
  68        /* Careful about overflows. Len == 0 means "as much as possible" */
  69        endbyte = offset + len;
  70        if (!len || endbyte < len)
  71                endbyte = -1;
  72        else
  73                endbyte--;              /* inclusive */
  74
  75        bdi = mapping->backing_dev_info;
  76
  77        switch (advice) {
  78        case POSIX_FADV_NORMAL:
  79                file->f_ra.ra_pages = bdi->ra_pages;
  80                spin_lock(&file->f_lock);
  81                file->f_mode &= ~FMODE_RANDOM;
  82                spin_unlock(&file->f_lock);
  83                break;
  84        case POSIX_FADV_RANDOM:
  85                spin_lock(&file->f_lock);
  86                file->f_mode |= FMODE_RANDOM;
  87                spin_unlock(&file->f_lock);
  88                break;
  89        case POSIX_FADV_SEQUENTIAL:
  90                file->f_ra.ra_pages = bdi->ra_pages * 2;
  91                spin_lock(&file->f_lock);
  92                file->f_mode &= ~FMODE_RANDOM;
  93                spin_unlock(&file->f_lock);
  94                break;
  95        case POSIX_FADV_WILLNEED:
  96                if (!mapping->a_ops->readpage) {
  97                        ret = -EINVAL;
  98                        break;
  99                }
 100
 101                /* First and last PARTIAL page! */
 102                start_index = offset >> PAGE_CACHE_SHIFT;
 103                end_index = endbyte >> PAGE_CACHE_SHIFT;
 104
 105                /* Careful about overflow on the "+1" */
 106                nrpages = end_index - start_index + 1;
 107                if (!nrpages)
 108                        nrpages = ~0UL;
 109                
 110                ret = force_page_cache_readahead(mapping, file,
 111                                start_index,
 112                                nrpages);
 113                if (ret > 0)
 114                        ret = 0;
 115                break;
 116        case POSIX_FADV_NOREUSE:
 117                break;
 118        case POSIX_FADV_DONTNEED:
 119                if (!bdi_write_congested(mapping->backing_dev_info))
 120                        filemap_flush(mapping);
 121
 122                /* First and last FULL page! */
 123                start_index = (offset+(PAGE_CACHE_SIZE-1)) >> PAGE_CACHE_SHIFT;
 124                end_index = (endbyte >> PAGE_CACHE_SHIFT);
 125
 126                if (end_index >= start_index)
 127                        invalidate_mapping_pages(mapping, start_index,
 128                                                end_index);
 129                break;
 130        default:
 131                ret = -EINVAL;
 132        }
 133out:
 134        fput(file);
 135        return ret;
 136}
 137#ifdef CONFIG_HAVE_SYSCALL_WRAPPERS
 138asmlinkage long SyS_fadvise64_64(long fd, loff_t offset, loff_t len, long advice)
 139{
 140        return SYSC_fadvise64_64((int) fd, offset, len, (int) advice);
 141}
 142SYSCALL_ALIAS(sys_fadvise64_64, SyS_fadvise64_64);
 143#endif
 144
 145#ifdef __ARCH_WANT_SYS_FADVISE64
 146
 147SYSCALL_DEFINE(fadvise64)(int fd, loff_t offset, size_t len, int advice)
 148{
 149        return sys_fadvise64_64(fd, offset, len, advice);
 150}
 151#ifdef CONFIG_HAVE_SYSCALL_WRAPPERS
 152asmlinkage long SyS_fadvise64(long fd, loff_t offset, long len, long advice)
 153{
 154        return SYSC_fadvise64((int) fd, offset, (size_t)len, (int)advice);
 155}
 156SYSCALL_ALIAS(sys_fadvise64, SyS_fadvise64);
 157#endif
 158
 159#endif
 160
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