/* * linux/fs/9p/vfs_addr.c * * This file contians vfs address (mmap) ops for 9P2000. * * Copyright (C) 2005 by Eric Van Hensbergen <ericvh@gmail.com> * Copyright (C) 2002 by Ron Minnich <rminnich@lanl.gov> * * This program is free software; you can redistribute it and/or modify * it under the terms of the GNU General Public License version 2 * as published by the Free Software Foundation. * * This program is distributed in the hope that it will be useful, * but WITHOUT ANY WARRANTY; without even the implied warranty of * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the * GNU General Public License for more details. * * You should have received a copy of the GNU General Public License * along with this program; if not, write to: * Free Software Foundation * 51 Franklin Street, Fifth Floor * Boston, MA 02111-1301 USA * */ #include <linux/module.h> #include <linux/errno.h> #include <linux/fs.h> #include <linux/file.h> #include <linux/stat.h> #include <linux/string.h> #include <linux/inet.h> #include <linux/pagemap.h> #include <linux/idr.h> #include <linux/sched.h> #include <linux/uio.h> #include <net/9p/9p.h> #include <net/9p/client.h> #include "v9fs.h" #include "v9fs_vfs.h" #include "cache.h" #include "fid.h" /** * v9fs_fid_readpage - read an entire page in from 9P * * @fid: fid being read * @page: structure to page * */ static int v9fs_fid_readpage(struct p9_fid *fid, struct page *page) { struct inode *inode = page->mapping->host; struct bio_vec bvec = {.bv_page = page, .bv_len = PAGE_SIZE}; struct iov_iter to; int retval, err; p9_debug(P9_DEBUG_VFS, "\n"); BUG_ON(!PageLocked(page)); retval = v9fs_readpage_from_fscache(inode, page); if (retval == 0) return retval; iov_iter_bvec(&to, ITER_BVEC | READ, &bvec, 1, PAGE_SIZE); retval = p9_client_read(fid, page_offset(page), &to, &err); if (err) { v9fs_uncache_page(inode, page); retval = err; goto done; } zero_user(page, retval, PAGE_SIZE - retval); flush_dcache_page(page); SetPageUptodate(page); v9fs_readpage_to_fscache(inode, page); retval = 0; done: unlock_page(page); return retval; } /** * v9fs_vfs_readpage - read an entire page in from 9P * * @filp: file being read * @page: structure to page * */ static int v9fs_vfs_readpage(struct file *filp, struct page *page) { return v9fs_fid_readpage(filp->private_data, page); } /** * v9fs_vfs_readpages - read a set of pages from 9P * * @filp: file being read * @mapping: the address space * @pages: list of pages to read * @nr_pages: count of pages to read * */ static int v9fs_vfs_readpages(struct file *filp, struct address_space *mapping, struct list_head *pages, unsigned nr_pages) { int ret = 0; struct inode *inode; inode = mapping->host; p9_debug(P9_DEBUG_VFS, "inode: %p file: %p\n", inode, filp); ret = v9fs_readpages_from_fscache(inode, mapping, pages, &nr_pages); if (ret == 0) return ret; ret = read_cache_pages(mapping, pages, (void *)v9fs_vfs_readpage, filp); p9_debug(P9_DEBUG_VFS, " = %d\n", ret); return ret; } /** * v9fs_release_page - release the private state associated with a page * * Returns 1 if the page can be released, false otherwise. */ static int v9fs_release_page(struct page *page, gfp_t gfp) { if (PagePrivate(page)) return 0; return v9fs_fscache_release_page(page, gfp); } /** * v9fs_invalidate_page - Invalidate a page completely or partially * * @page: structure to page * @offset: offset in the page */ static void v9fs_invalidate_page(struct page *page, unsigned int offset, unsigned int length) { /* * If called with zero offset, we should release * the private state assocated with the page */ if (offset == 0 && length == PAGE_CACHE_SIZE) v9fs_fscache_invalidate_page(page); } static int v9fs_vfs_writepage_locked(struct page *page) { struct inode *inode = page->mapping->host; struct v9fs_inode *v9inode = V9FS_I(inode); loff_t size = i_size_read(inode); struct iov_iter from; struct bio_vec bvec; int err, len; if (page->index == size >> PAGE_CACHE_SHIFT) len = size & ~PAGE_CACHE_MASK; else len = PAGE_CACHE_SIZE; bvec.bv_page = page; bvec.bv_offset = 0; bvec.bv_len = len; iov_iter_bvec(&from, ITER_BVEC | WRITE, &bvec, 1, len); /* We should have writeback_fid always set */ BUG_ON(!v9inode->writeback_fid); set_page_writeback(page); p9_client_write(v9inode->writeback_fid, page_offset(page), &from, &err); end_page_writeback(page); return err; } static int v9fs_vfs_writepage(struct page *page, struct writeback_control *wbc) { int retval; p9_debug(P9_DEBUG_VFS, "page %p\n", page); retval = v9fs_vfs_writepage_locked(page); if (retval < 0) { if (retval == -EAGAIN) { redirty_page_for_writepage(wbc, page); retval = 0; } else { SetPageError(page); mapping_set_error(page->mapping, retval); } } else retval = 0; unlock_page(page); return retval; } /** * v9fs_launder_page - Writeback a dirty page * Returns 0 on success. */ static int v9fs_launder_page(struct page *page) { int retval; struct inode *inode = page->mapping->host; v9fs_fscache_wait_on_page_write(inode, page); if (clear_page_dirty_for_io(page)) { retval = v9fs_vfs_writepage_locked(page); if (retval) return retval; } return 0; } /** * v9fs_direct_IO - 9P address space operation for direct I/O * @iocb: target I/O control block * @pos: offset in file to begin the operation * * The presence of v9fs_direct_IO() in the address space ops vector * allowes open() O_DIRECT flags which would have failed otherwise. * * In the non-cached mode, we shunt off direct read and write requests before * the VFS gets them, so this method should never be called. * * Direct IO is not 'yet' supported in the cached mode. Hence when * this routine is called through generic_file_aio_read(), the read/write fails * with an error. * */ static ssize_t v9fs_direct_IO(struct kiocb *iocb, struct iov_iter *iter, loff_t pos) { struct file *file = iocb->ki_filp; ssize_t n; int err = 0; if (iov_iter_rw(iter) == WRITE) { n = p9_client_write(file->private_data, pos, iter, &err); if (n) { struct inode *inode = file_inode(file); loff_t i_size = i_size_read(inode); if (pos + n > i_size) inode_add_bytes(inode, pos + n - i_size); } } else { n = p9_client_read(file->private_data, pos, iter, &err); } return n ? n : err; } static int v9fs_write_begin(struct file *filp, struct address_space *mapping, loff_t pos, unsigned len, unsigned flags, struct page **pagep, void **fsdata) { int retval = 0; struct page *page; struct v9fs_inode *v9inode; pgoff_t index = pos >> PAGE_CACHE_SHIFT; struct inode *inode = mapping->host; p9_debug(P9_DEBUG_VFS, "filp %p, mapping %p\n", filp, mapping); v9inode = V9FS_I(inode); start: page = grab_cache_page_write_begin(mapping, index, flags); if (!page) { retval = -ENOMEM; goto out; } BUG_ON(!v9inode->writeback_fid); if (PageUptodate(page)) goto out; if (len == PAGE_CACHE_SIZE) goto out; retval = v9fs_fid_readpage(v9inode->writeback_fid, page); page_cache_release(page); if (!retval) goto start; out: *pagep = page; return retval; } static int v9fs_write_end(struct file *filp, struct address_space *mapping, loff_t pos, unsigned len, unsigned copied, struct page *page, void *fsdata) { loff_t last_pos = pos + copied; struct inode *inode = page->mapping->host; p9_debug(P9_DEBUG_VFS, "filp %p, mapping %p\n", filp, mapping); if (unlikely(copied < len)) { /* * zero out the rest of the area */ unsigned from = pos & (PAGE_CACHE_SIZE - 1); zero_user(page, from + copied, len - copied); flush_dcache_page(page); } if (!PageUptodate(page)) SetPageUptodate(page); /* * No need to use i_size_read() here, the i_size * cannot change under us because we hold the i_mutex. */ if (last_pos > inode->i_size) { inode_add_bytes(inode, last_pos - inode->i_size); i_size_write(inode, last_pos); } set_page_dirty(page); unlock_page(page); page_cache_release(page); return copied; } const struct address_space_operations v9fs_addr_operations = { .readpage = v9fs_vfs_readpage, .readpages = v9fs_vfs_readpages, .set_page_dirty = __set_page_dirty_nobuffers, .writepage = v9fs_vfs_writepage, .write_begin = v9fs_write_begin, .write_end = v9fs_write_end, .releasepage = v9fs_release_page, .invalidatepage = v9fs_invalidate_page, .launder_page = v9fs_launder_page, .direct_IO = v9fs_direct_IO, };