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1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 101 102 103 104 105 106 107 108 109 110 111 | /* * mm/fadvise.c * * Copyright (C) 2002, Linus Torvalds * * 11Jan2003 akpm@digeo.com * Initial version. */ #include <linux/kernel.h> #include <linux/file.h> #include <linux/fs.h> #include <linux/mm.h> #include <linux/pagemap.h> #include <linux/backing-dev.h> #include <linux/pagevec.h> #include <linux/fadvise.h> #include <linux/syscalls.h> #include <asm/unistd.h> /* * POSIX_FADV_WILLNEED could set PG_Referenced, and POSIX_FADV_NOREUSE could * deactivate the pages and clear PG_Referenced. */ asmlinkage long sys_fadvise64_64(int fd, loff_t offset, loff_t len, int advice) { struct file *file = fget(fd); struct address_space *mapping; struct backing_dev_info *bdi; loff_t endbyte; pgoff_t start_index; pgoff_t end_index; unsigned long nrpages; int ret = 0; if (!file) return -EBADF; mapping = file->f_mapping; if (!mapping || len < 0) { ret = -EINVAL; goto out; } /* Careful about overflows. Len == 0 means "as much as possible" */ endbyte = offset + len; if (!len || endbyte < len) endbyte = -1; bdi = mapping->backing_dev_info; switch (advice) { case POSIX_FADV_NORMAL: file->f_ra.ra_pages = bdi->ra_pages; break; case POSIX_FADV_RANDOM: file->f_ra.ra_pages = 0; break; case POSIX_FADV_SEQUENTIAL: file->f_ra.ra_pages = bdi->ra_pages * 2; break; case POSIX_FADV_WILLNEED: case POSIX_FADV_NOREUSE: if (!mapping->a_ops->readpage) { ret = -EINVAL; break; } /* First and last PARTIAL page! */ start_index = offset >> PAGE_CACHE_SHIFT; end_index = (endbyte-1) >> PAGE_CACHE_SHIFT; /* Careful about overflow on the "+1" */ nrpages = end_index - start_index + 1; if (!nrpages) nrpages = ~0UL; ret = force_page_cache_readahead(mapping, file, start_index, max_sane_readahead(nrpages)); if (ret > 0) ret = 0; break; case POSIX_FADV_DONTNEED: if (!bdi_write_congested(mapping->backing_dev_info)) filemap_flush(mapping); /* First and last FULL page! */ start_index = (offset + (PAGE_CACHE_SIZE-1)) >> PAGE_CACHE_SHIFT; end_index = (endbyte >> PAGE_CACHE_SHIFT); if (end_index > start_index) invalidate_mapping_pages(mapping, start_index, end_index-1); break; default: ret = -EINVAL; } out: fput(file); return ret; } #ifdef __ARCH_WANT_SYS_FADVISE64 asmlinkage long sys_fadvise64(int fd, loff_t offset, size_t len, int advice) { return sys_fadvise64_64(fd, offset, len, advice); } #endif |