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/syscalls.h> 19 20 #include <asm/unistd.h> 21 22 /* 23 * POSIX_FADV_WILLNEED could set PG_Referenced, and POSIX_FADV_NOREUSE could 24 * deactivate the pages and clear PG_Referenced. 25 */ 26 asmlinkage long sys_fadvise64_64(int fd, loff_t offset, loff_t len, int advice) 27 { 28 struct file *file = fget(fd); 29 struct address_space *mapping; 30 struct backing_dev_info *bdi; 31 loff_t endbyte; 32 pgoff_t start_index; 33 pgoff_t end_index; 34 unsigned long nrpages; 35 int ret = 0; 36 37 if (!file) 38 return -EBADF; 39 40 mapping = file->f_mapping; 41 if (!mapping || len < 0) { 42 ret = -EINVAL; 43 goto out; 44 } 45 46 if (mapping->a_ops->get_xip_page) 47 /* no bad return value, but ignore advice */ 48 goto out; 49 50 /* Careful about overflows. Len == 0 means "as much as possible" */ 51 endbyte = offset + len; 52 if (!len || endbyte < len) 53 endbyte = -1; 54 55 bdi = mapping->backing_dev_info; 56 57 switch (advice) { 58 case POSIX_FADV_NORMAL: 59 file->f_ra.ra_pages = bdi->ra_pages; 60 break; 61 case POSIX_FADV_RANDOM: 62 file->f_ra.ra_pages = 0; 63 break; 64 case POSIX_FADV_SEQUENTIAL: 65 file->f_ra.ra_pages = bdi->ra_pages * 2; 66 break; 67 case POSIX_FADV_WILLNEED: 68 case POSIX_FADV_NOREUSE: 69 if (!mapping->a_ops->readpage) { 70 ret = -EINVAL; 71 break; 72 } 73 74 /* First and last PARTIAL page! */ 75 start_index = offset >> PAGE_CACHE_SHIFT; 76 end_index = (endbyte-1) >> PAGE_CACHE_SHIFT; 77 78 /* Careful about overflow on the "+1" */ 79 nrpages = end_index - start_index + 1; 80 if (!nrpages) 81 nrpages = ~0UL; 82 83 ret = force_page_cache_readahead(mapping, file, 84 start_index, 85 max_sane_readahead(nrpages)); 86 if (ret > 0) 87 ret = 0; 88 break; 89 case POSIX_FADV_DONTNEED: 90 if (!bdi_write_congested(mapping->backing_dev_info)) 91 filemap_flush(mapping); 92 93 /* First and last FULL page! */ 94 start_index = (offset + (PAGE_CACHE_SIZE-1)) >> PAGE_CACHE_SHIFT; 95 end_index = (endbyte >> PAGE_CACHE_SHIFT); 96 97 if (end_index > start_index) 98 invalidate_mapping_pages(mapping, start_index, end_index-1); 99 break; 100 default: 101 ret = -EINVAL; 102 } 103 out: 104 fput(file); 105 return ret; 106 } 107 108 #ifdef __ARCH_WANT_SYS_FADVISE64 109 110 asmlinkage long sys_fadvise64(int fd, loff_t offset, size_t len, int advice) 111 { 112 return sys_fadvise64_64(fd, offset, len, advice); 113 } 114 115 #endif 116