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 #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 * LINUX_FADV_ASYNC_WRITE: start async writeout of any dirty pages between file 28 * offsets `offset' and `offset+len' inclusive. Any pages which are currently 29 * under writeout are skipped, whether or not they are dirty. 30 * 31 * LINUX_FADV_WRITE_WAIT: wait upon writeout of any dirty pages between file 32 * offsets `offset' and `offset+len'. 33 * 34 * By combining these two operations the application may do several things: 35 * 36 * LINUX_FADV_ASYNC_WRITE: push some or all of the dirty pages at the disk. 37 * 38 */ 39 asmlinkage long sys_fadvise64_64(int fd, loff_t offset, loff_t len, int advice) 40 { 41 struct file *file = fget(fd); 42 struct address_space *mapping; 43 struct backing_dev_info *bdi; 44 loff_t endbyte; /* inclusive */ 45 pgoff_t start_index; 46 pgoff_t end_index; 47 unsigned long nrpages; 48 int ret = 0; 49 50 if (!file) 51 return -EBADF; 52 53 if (S_ISFIFO(file->f_dentry->d_inode->i_mode)) { 54 ret = -ESPIPE; 55 goto out; 56 } 57 58 mapping = file->f_mapping; 59 if (!mapping || len < 0) { 60 ret = -EINVAL; 61 goto out; 62 } 63 64 if (mapping->a_ops->get_xip_page) 65 /* no bad return value, but ignore advice */ 66 goto out; 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 break; 81 case POSIX_FADV_RANDOM: 82 file->f_ra.ra_pages = 0; 83 break; 84 case POSIX_FADV_SEQUENTIAL: 85 file->f_ra.ra_pages = bdi->ra_pages * 2; 86 break; 87 case POSIX_FADV_WILLNEED: 88 case POSIX_FADV_NOREUSE: 89 if (!mapping->a_ops->readpage) { 90 ret = -EINVAL; 91 break; 92 } 93 94 /* First and last PARTIAL page! */ 95 start_index = offset >> PAGE_CACHE_SHIFT; 96 end_index = endbyte >> PAGE_CACHE_SHIFT; 97 98 /* Careful about overflow on the "+1" */ 99 nrpages = end_index - start_index + 1; 100 if (!nrpages) 101 nrpages = ~0UL; 102 103 ret = force_page_cache_readahead(mapping, file, 104 start_index, 105 max_sane_readahead(nrpages)); 106 if (ret > 0) 107 ret = 0; 108 break; 109 case POSIX_FADV_DONTNEED: 110 if (!bdi_write_congested(mapping->backing_dev_info)) 111 filemap_flush(mapping); 112 113 /* First and last FULL page! */ 114 start_index = (offset+(PAGE_CACHE_SIZE-1)) >> PAGE_CACHE_SHIFT; 115 end_index = (endbyte >> PAGE_CACHE_SHIFT); 116 117 if (end_index >= start_index) 118 invalidate_mapping_pages(mapping, start_index, 119 end_index); 120 break; 121 default: 122 ret = -EINVAL; 123 } 124 out: 125 fput(file); 126 return ret; 127 } 128 129 #ifdef __ARCH_WANT_SYS_FADVISE64 130 131 asmlinkage long sys_fadvise64(int fd, loff_t offset, size_t len, int advice) 132 { 133 return sys_fadvise64_64(fd, offset, len, advice); 134 } 135 136 #endif 137