mm/fadvise.c

   1 /*
   2  * mm/fadvise.c
   3  *
   4  * Copyright (C) 2002, Linus Torvalds
   5  *
   6  * 11Jan2003    akpm@digeo.com
   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
  19 /*
  20  * POSIX_FADV_WILLNEED could set PG_Referenced, and POSIX_FADV_NOREUSE could
  21  * deactivate the pages and clear PG_Referenced.
  22  */
  23 asmlinkage long sys_fadvise64_64(int fd, loff_t offset, loff_t len, int advice)
  24 {
  25         struct file *file = fget(fd);
  26         struct inode *inode;
  27         struct address_space *mapping;
  28         struct backing_dev_info *bdi;
  29         pgoff_t start_index;
  30         pgoff_t end_index;
  31         int ret = 0;
  32
  33         if (!file)
  34                 return -EBADF;
  35
  36         inode = file->f_dentry->d_inode;
  37         mapping = inode->i_mapping;
  38         if (!mapping) {
  39                 ret = -EINVAL;
  40                 goto out;
  41         }
  42
  43         bdi = mapping->backing_dev_info;
  44
  45         switch (advice) {
  46         case POSIX_FADV_NORMAL:
  47                 file->f_ra.ra_pages = bdi->ra_pages;
  48                 break;
  49         case POSIX_FADV_RANDOM:
  50                 file->f_ra.ra_pages = 0;
  51                 break;
  52         case POSIX_FADV_SEQUENTIAL:
  53                 file->f_ra.ra_pages = bdi->ra_pages * 2;
  54                 break;
  55         case POSIX_FADV_WILLNEED:
  56         case POSIX_FADV_NOREUSE:
  57                 if (!mapping->a_ops->readpage) {
  58                         ret = -EINVAL;
  59                         break;
  60                 }
  61                 ret = force_page_cache_readahead(mapping, file,
  62                                 offset >> PAGE_CACHE_SHIFT,
  63                                 max_sane_readahead(len >> PAGE_CACHE_SHIFT));
  64                 if (ret > 0)
  65                         ret = 0;
  66                 break;
  67         case POSIX_FADV_DONTNEED:
  68                 if (!bdi_write_congested(mapping->backing_dev_info))
  69                         filemap_flush(mapping);
  70                 start_index = offset >> PAGE_CACHE_SHIFT;
  71                 end_index = (offset + len + PAGE_CACHE_SIZE - 1) >>
  72                                                 PAGE_CACHE_SHIFT;
  73                 invalidate_mapping_pages(mapping, start_index, end_index);
  74                 break;
  75         default:
  76                 ret = -EINVAL;
  77         }
  78 out:
  79         fput(file);
  80         return ret;
  81 }
  82
  83 asmlinkage long sys_fadvise64(int fd, loff_t offset, size_t len, int advice)
  84 {
  85         return sys_fadvise64_64(fd, offset, len, advice);
  86 }
  87