Linux/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 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_fdatawrite_range(mapping, offset, endbyte,
121                                                    WB_SYNC_NONE);
122 
123                 /* First and last FULL page! */
124                 start_index = (offset+(PAGE_CACHE_SIZE-1)) >> PAGE_CACHE_SHIFT;
125                 end_index = (endbyte >> PAGE_CACHE_SHIFT);
126 
127                 if (end_index >= start_index)
128                         invalidate_mapping_pages(mapping, start_index,
129                                                 end_index);
130                 break;
131         default:
132                 ret = -EINVAL;
133         }
134 out:
135         fput(file);
136         return ret;
137 }
138 #ifdef CONFIG_HAVE_SYSCALL_WRAPPERS
139 asmlinkage long SyS_fadvise64_64(long fd, loff_t offset, loff_t len, long advice)
140 {
141         return SYSC_fadvise64_64((int) fd, offset, len, (int) advice);
142 }
143 SYSCALL_ALIAS(sys_fadvise64_64, SyS_fadvise64_64);
144 #endif
145 
146 #ifdef __ARCH_WANT_SYS_FADVISE64
147 
148 SYSCALL_DEFINE(fadvise64)(int fd, loff_t offset, size_t len, int advice)
149 {
150         return sys_fadvise64_64(fd, offset, len, advice);
151 }
152 #ifdef CONFIG_HAVE_SYSCALL_WRAPPERS
153 asmlinkage long SyS_fadvise64(long fd, loff_t offset, long len, long advice)
154 {
155         return SYSC_fadvise64((int) fd, offset, (size_t)len, (int)advice);
156 }
157 SYSCALL_ALIAS(sys_fadvise64, SyS_fadvise64);
158 #endif
159 
160 #endif
161

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