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 asmlinkage long sys_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 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 if (!mapping->a_ops->readpage) { 89 ret = -EINVAL; 90 break; 91 } 92 93 /* First and last PARTIAL page! */ 94 start_index = offset >> PAGE_CACHE_SHIFT; 95 end_index = endbyte >> PAGE_CACHE_SHIFT; 96 97 /* Careful about overflow on the "+1" */ 98 nrpages = end_index - start_index + 1; 99 if (!nrpages) 100 nrpages = ~0UL; 101 102 ret = force_page_cache_readahead(mapping, file, 103 start_index, 104 max_sane_readahead(nrpages)); 105 if (ret > 0) 106 ret = 0; 107 break; 108 case POSIX_FADV_NOREUSE: 109 break; 110 case POSIX_FADV_DONTNEED: 111 if (!bdi_write_congested(mapping->backing_dev_info)) 112 filemap_flush(mapping); 113 114 /* First and last FULL page! */ 115 start_index = (offset+(PAGE_CACHE_SIZE-1)) >> PAGE_CACHE_SHIFT; 116 end_index = (endbyte >> PAGE_CACHE_SHIFT); 117 118 if (end_index >= start_index) 119 invalidate_mapping_pages(mapping, start_index, 120 end_index); 121 break; 122 default: 123 ret = -EINVAL; 124 } 125 out: 126 fput(file); 127 return ret; 128 } 129 130 #ifdef __ARCH_WANT_SYS_FADVISE64 131 132 asmlinkage long sys_fadvise64(int fd, loff_t offset, size_t len, int advice) 133 { 134 return sys_fadvise64_64(fd, offset, len, advice); 135 } 136 137 #endif 138