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 #include <linux/swap.h>
  21
  22 #include <asm/unistd.h>
  23
  24 /*
  25  * POSIX_FADV_WILLNEED could set PG_Referenced, and POSIX_FADV_NOREUSE could
  26  * deactivate the pages and clear PG_Referenced.
  27  */
  28 SYSCALL_DEFINE(fadvise64_64)(int fd, loff_t offset, loff_t len, int advice)
  29 {
  30         struct file *file = fget(fd);
  31         struct address_space *mapping;
  32         struct backing_dev_info *bdi;
  33         loff_t endbyte;                 /* inclusive */
  34         pgoff_t start_index;
  35         pgoff_t end_index;
  36         unsigned long nrpages;
  37         int ret = 0;
  38
  39         if (!file)
  40                 return -EBADF;
  41
  42         if (S_ISFIFO(file->f_path.dentry->d_inode->i_mode)) {
  43                 ret = -ESPIPE;
  44                 goto out;
  45         }
  46
  47         mapping = file->f_mapping;
  48         if (!mapping || len < 0) {
  49                 ret = -EINVAL;
  50                 goto out;
  51         }
  52
  53         if (mapping->a_ops->get_xip_mem) {
  54                 switch (advice) {
  55                 case POSIX_FADV_NORMAL:
  56                 case POSIX_FADV_RANDOM:
  57                 case POSIX_FADV_SEQUENTIAL:
  58                 case POSIX_FADV_WILLNEED:
  59                 case POSIX_FADV_NOREUSE:
  60                 case POSIX_FADV_DONTNEED:
  61                         /* no bad return value, but ignore advice */
  62                         break;
  63                 default:
  64                         ret = -EINVAL;
  65                 }
  66                 goto out;
  67         }
  68
  69         /* Careful about overflows. Len == 0 means "as much as possible" */
  70         endbyte = offset + len;
  71         if (!len || endbyte < len)
  72                 endbyte = -1;
  73         else
  74                 endbyte--;              /* inclusive */
  75
  76         bdi = mapping->backing_dev_info;
  77
  78         switch (advice) {
  79         case POSIX_FADV_NORMAL:
  80                 file->f_ra.ra_pages = bdi->ra_pages;
  81                 spin_lock(&file->f_lock);
  82                 file->f_mode &= ~FMODE_RANDOM;
  83                 spin_unlock(&file->f_lock);
  84                 break;
  85         case POSIX_FADV_RANDOM:
  86                 spin_lock(&file->f_lock);
  87                 file->f_mode |= FMODE_RANDOM;
  88                 spin_unlock(&file->f_lock);
  89                 break;
  90         case POSIX_FADV_SEQUENTIAL:
  91                 file->f_ra.ra_pages = bdi->ra_pages * 2;
  92                 spin_lock(&file->f_lock);
  93                 file->f_mode &= ~FMODE_RANDOM;
  94                 spin_unlock(&file->f_lock);
  95                 break;
  96         case POSIX_FADV_WILLNEED:
  97                 if (!mapping->a_ops->readpage) {
  98                         ret = -EINVAL;
  99                         break;
 100                 }
 101
 102                 /* First and last PARTIAL page! */
 103                 start_index = offset >> PAGE_CACHE_SHIFT;
 104                 end_index = endbyte >> PAGE_CACHE_SHIFT;
 105
 106                 /* Careful about overflow on the "+1" */
 107                 nrpages = end_index - start_index + 1;
 108                 if (!nrpages)
 109                         nrpages = ~0UL;
 110
 111                 ret = force_page_cache_readahead(mapping, file,
 112                                 start_index,
 113                                 nrpages);
 114                 if (ret > 0)
 115                         ret = 0;
 116                 break;
 117         case POSIX_FADV_NOREUSE:
 118                 break;
 119         case POSIX_FADV_DONTNEED:
 120                 if (!bdi_write_congested(mapping->backing_dev_info))
 121                         __filemap_fdatawrite_range(mapping, offset, endbyte,
 122                                                    WB_SYNC_NONE);
 123
 124                 /* First and last FULL page! */
 125                 start_index = (offset+(PAGE_CACHE_SIZE-1)) >> PAGE_CACHE_SHIFT;
 126                 end_index = (endbyte >> PAGE_CACHE_SHIFT);
 127
 128                 if (end_index >= start_index) {
 129                         unsigned long count = invalidate_mapping_pages(mapping,
 130                                                 start_index, end_index);
 131
 132                         /*
 133                          * If fewer pages were invalidated than expected then
 134                          * it is possible that some of the pages were on
 135                          * a per-cpu pagevec for a remote CPU. Drain all
 136                          * pagevecs and try again.
 137                          */
 138                         if (count < (end_index - start_index + 1)) {
 139                                 lru_add_drain_all();
 140                                 invalidate_mapping_pages(mapping, start_index,
 141                                                 end_index);
 142                         }
 143                 }
 144                 break;
 145         default:
 146                 ret = -EINVAL;
 147         }
 148 out:
 149         fput(file);
 150         return ret;
 151 }
 152 #ifdef CONFIG_HAVE_SYSCALL_WRAPPERS
 153 asmlinkage long SyS_fadvise64_64(long fd, loff_t offset, loff_t len, long advice)
 154 {
 155         return SYSC_fadvise64_64((int) fd, offset, len, (int) advice);
 156 }
 157 SYSCALL_ALIAS(sys_fadvise64_64, SyS_fadvise64_64);
 158 #endif
 159
 160 #ifdef __ARCH_WANT_SYS_FADVISE64
 161
 162 SYSCALL_DEFINE(fadvise64)(int fd, loff_t offset, size_t len, int advice)
 163 {
 164         return sys_fadvise64_64(fd, offset, len, advice);
 165 }
 166 #ifdef CONFIG_HAVE_SYSCALL_WRAPPERS
 167 asmlinkage long SyS_fadvise64(long fd, loff_t offset, long len, long advice)
 168 {
 169         return SYSC_fadvise64((int) fd, offset, (size_t)len, (int)advice);
 170 }
 171 SYSCALL_ALIAS(sys_fadvise64, SyS_fadvise64);
 172 #endif
 173
 174 #endif