/* * mm/fadvise.c * * Copyright (C) 2002, Linus Torvalds * * 11Jan2003 Andrew Morton * 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/writeback.h> #include <linux/syscalls.h> #include <linux/swap.h> #include <asm/unistd.h> /* * POSIX_FADV_WILLNEED could set PG_Referenced, and POSIX_FADV_NOREUSE could * deactivate the pages and clear PG_Referenced. */ SYSCALL_DEFINE4(fadvise64_64, int, fd, loff_t, offset, loff_t, len, int, advice) { struct fd f = fdget(fd); struct address_space *mapping; struct backing_dev_info *bdi; loff_t endbyte; /* inclusive */ pgoff_t start_index; pgoff_t end_index; unsigned long nrpages; int ret = 0; if (!f.file) return -EBADF; if (S_ISFIFO(file_inode(f.file)->i_mode)) { ret = -ESPIPE; goto out; } mapping = f.file->f_mapping; if (!mapping || len < 0) { ret = -EINVAL; goto out; } if (mapping->a_ops->get_xip_mem) { switch (advice) { case POSIX_FADV_NORMAL: case POSIX_FADV_RANDOM: case POSIX_FADV_SEQUENTIAL: case POSIX_FADV_WILLNEED: case POSIX_FADV_NOREUSE: case POSIX_FADV_DONTNEED: /* no bad return value, but ignore advice */ break; default: ret = -EINVAL; } goto out; } /* Careful about overflows. Len == 0 means "as much as possible" */ endbyte = offset + len; if (!len || endbyte < len) endbyte = -1; else endbyte--; /* inclusive */ bdi = mapping->backing_dev_info; switch (advice) { case POSIX_FADV_NORMAL: f.file->f_ra.ra_pages = bdi->ra_pages; spin_lock(&f.file->f_lock); f.file->f_mode &= ~FMODE_RANDOM; spin_unlock(&f.file->f_lock); break; case POSIX_FADV_RANDOM: spin_lock(&f.file->f_lock); f.file->f_mode |= FMODE_RANDOM; spin_unlock(&f.file->f_lock); break; case POSIX_FADV_SEQUENTIAL: f.file->f_ra.ra_pages = bdi->ra_pages * 2; spin_lock(&f.file->f_lock); f.file->f_mode &= ~FMODE_RANDOM; spin_unlock(&f.file->f_lock); break; case POSIX_FADV_WILLNEED: /* First and last PARTIAL page! */ start_index = offset >> PAGE_CACHE_SHIFT; end_index = endbyte >> PAGE_CACHE_SHIFT; /* Careful about overflow on the "+1" */ nrpages = end_index - start_index + 1; if (!nrpages) nrpages = ~0UL; /* * Ignore return value because fadvise() shall return * success even if filesystem can't retrieve a hint, */ force_page_cache_readahead(mapping, f.file, start_index, nrpages); break; case POSIX_FADV_NOREUSE: break; case POSIX_FADV_DONTNEED: if (!bdi_write_congested(mapping->backing_dev_info)) __filemap_fdatawrite_range(mapping, offset, endbyte, WB_SYNC_NONE); /* * First and last FULL page! Partial pages are deliberately * preserved on the expectation that it is better to preserve * needed memory than to discard unneeded memory. */ start_index = (offset+(PAGE_CACHE_SIZE-1)) >> PAGE_CACHE_SHIFT; end_index = (endbyte >> PAGE_CACHE_SHIFT); if (end_index >= start_index) { unsigned long count = invalidate_mapping_pages(mapping, start_index, end_index); /* * If fewer pages were invalidated than expected then * it is possible that some of the pages were on * a per-cpu pagevec for a remote CPU. Drain all * pagevecs and try again. */ if (count < (end_index - start_index + 1)) { lru_add_drain_all(); invalidate_mapping_pages(mapping, start_index, end_index); } } break; default: ret = -EINVAL; } out: fdput(f); return ret; } #ifdef __ARCH_WANT_SYS_FADVISE64 SYSCALL_DEFINE4(fadvise64, int, fd, loff_t, offset, size_t, len, int, advice) { return sys_fadvise64_64(fd, offset, len, advice); } #endif