mm/fadvise.c

   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  */
  27 SYSCALL_DEFINE(fadvise64_64)(int fd, loff_t offset, loff_t len, int advice)
  28 {
  29         struct fd f = fdget(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 (!f.file)
  39                 return -EBADF;
  40
  41         if (S_ISFIFO(f.file->f_path.dentry->d_inode->i_mode)) {
  42                 ret = -ESPIPE;
  43                 goto out;
  44         }
  45
  46         mapping = f.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                 f.file->f_ra.ra_pages = bdi->ra_pages;
  80                 spin_lock(&f.file->f_lock);
  81                 f.file->f_mode &= ~FMODE_RANDOM;
  82                 spin_unlock(&f.file->f_lock);
  83                 break;
  84         case POSIX_FADV_RANDOM:
  85                 spin_lock(&f.file->f_lock);
  86                 f.file->f_mode |= FMODE_RANDOM;
  87                 spin_unlock(&f.file->f_lock);
  88                 break;
  89         case POSIX_FADV_SEQUENTIAL:
  90                 f.file->f_ra.ra_pages = bdi->ra_pages * 2;
  91                 spin_lock(&f.file->f_lock);
  92                 f.file->f_mode &= ~FMODE_RANDOM;
  93                 spin_unlock(&f.file->f_lock);
  94                 break;
  95         case POSIX_FADV_WILLNEED:
  96                 /* First and last PARTIAL page! */
  97                 start_index = offset >> PAGE_CACHE_SHIFT;
  98                 end_index = endbyte >> PAGE_CACHE_SHIFT;
  99
 100                 /* Careful about overflow on the "+1" */
 101                 nrpages = end_index - start_index + 1;
 102                 if (!nrpages)
 103                         nrpages = ~0UL;
 104
 105                 /*
 106                  * Ignore return value because fadvise() shall return
 107                  * success even if filesystem can't retrieve a hint,
 108                  */
 109                 force_page_cache_readahead(mapping, f.file, start_index,
 110                                            nrpages);
 111                 break;
 112         case POSIX_FADV_NOREUSE:
 113                 break;
 114         case POSIX_FADV_DONTNEED:
 115                 if (!bdi_write_congested(mapping->backing_dev_info))
 116                         __filemap_fdatawrite_range(mapping, offset, endbyte,
 117                                                    WB_SYNC_NONE);
 118
 119                 /* First and last FULL page! */
 120                 start_index = (offset+(PAGE_CACHE_SIZE-1)) >> PAGE_CACHE_SHIFT;
 121                 end_index = (endbyte >> PAGE_CACHE_SHIFT);
 122
 123                 if (end_index >= start_index)
 124                         invalidate_mapping_pages(mapping, start_index,
 125                                                 end_index);
 126                 break;
 127         default:
 128                 ret = -EINVAL;
 129         }
 130 out:
 131         fdput(f);
 132         return ret;
 133 }
 134 #ifdef CONFIG_HAVE_SYSCALL_WRAPPERS
 135 asmlinkage long SyS_fadvise64_64(long fd, loff_t offset, loff_t len, long advice)
 136 {
 137         return SYSC_fadvise64_64((int) fd, offset, len, (int) advice);
 138 }
 139 SYSCALL_ALIAS(sys_fadvise64_64, SyS_fadvise64_64);
 140 #endif
 141
 142 #ifdef __ARCH_WANT_SYS_FADVISE64
 143
 144 SYSCALL_DEFINE(fadvise64)(int fd, loff_t offset, size_t len, int advice)
 145 {
 146         return sys_fadvise64_64(fd, offset, len, advice);
 147 }
 148 #ifdef CONFIG_HAVE_SYSCALL_WRAPPERS
 149 asmlinkage long SyS_fadvise64(long fd, loff_t offset, long len, long advice)
 150 {
 151         return SYSC_fadvise64((int) fd, offset, (size_t)len, (int)advice);
 152 }
 153 SYSCALL_ALIAS(sys_fadvise64, SyS_fadvise64);
 154 #endif
 155
 156 #endif