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 /* Careful about overflows. Len == 0 means "as much as possible" */ 47 endbyte = offset + len; 48 if (!len || endbyte < len) 49 endbyte = -1; 50 51 bdi = mapping->backing_dev_info; 52 53 switch (advice) { 54 case POSIX_FADV_NORMAL: 55 file->f_ra.ra_pages = bdi->ra_pages; 56 break; 57 case POSIX_FADV_RANDOM: 58 file->f_ra.ra_pages = 0; 59 break; 60 case POSIX_FADV_SEQUENTIAL: 61 file->f_ra.ra_pages = bdi->ra_pages * 2; 62 break; 63 case POSIX_FADV_WILLNEED: 64 case POSIX_FADV_NOREUSE: 65 if (!mapping->a_ops->readpage) { 66 ret = -EINVAL; 67 break; 68 } 69 70 /* First and last PARTIAL page! */ 71 start_index = offset >> PAGE_CACHE_SHIFT; 72 end_index = (endbyte-1) >> PAGE_CACHE_SHIFT; 73 74 /* Careful about overflow on the "+1" */ 75 nrpages = end_index - start_index + 1; 76 if (!nrpages) 77 nrpages = ~0UL; 78 79 ret = force_page_cache_readahead(mapping, file, 80 start_index, 81 max_sane_readahead(nrpages)); 82 if (ret > 0) 83 ret = 0; 84 break; 85 case POSIX_FADV_DONTNEED: 86 if (!bdi_write_congested(mapping->backing_dev_info)) 87 filemap_flush(mapping); 88 89 /* First and last FULL page! */ 90 start_index = (offset + (PAGE_CACHE_SIZE-1)) >> PAGE_CACHE_SHIFT; 91 end_index = (endbyte >> PAGE_CACHE_SHIFT); 92 93 if (end_index > start_index) 94 invalidate_mapping_pages(mapping, start_index, end_index-1); 95 break; 96 default: 97 ret = -EINVAL; 98 } 99 out: 100 fput(file); 101 return ret; 102 } 103 104 #ifdef __ARCH_WANT_SYS_FADVISE64 105 106 asmlinkage long sys_fadvise64(int fd, loff_t offset, size_t len, int advice) 107 { 108 return sys_fadvise64_64(fd, offset, len, advice); 109 } 110 111 #endif 112