/* * 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/writeback.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. * * LINUX_FADV_ASYNC_WRITE: start async writeout of any dirty pages between file * offsets `offset' and `offset+len' inclusive. Any pages which are currently * under writeout are skipped, whether or not they are dirty. * * LINUX_FADV_WRITE_WAIT: wait upon writeout of any dirty pages between file * offsets `offset' and `offset+len'. * * By combining these two operations the application may do several things: * * LINUX_FADV_ASYNC_WRITE: push some or all of the dirty pages at the disk. * */ 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; /* inclusive */ pgoff_t start_index; pgoff_t end_index; unsigned long nrpages; int ret = 0; if (!file) return -EBADF; if (S_ISFIFO(file->f_dentry->d_inode->i_mode)) { ret = -ESPIPE; goto out; } mapping = file->f_mapping; if (!mapping || len < 0) { ret = -EINVAL; goto out; } if (mapping->a_ops->get_xip_page) /* no bad return value, but ignore advice */ 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: 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 >> 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); 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