| // SPDX-License-Identifier: GPL-2.0-only |
| /* |
| * 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> |
| */ |
| |
| #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 <linux/bvec.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 |
| * @data: Opaque pointer to the fid being read |
| * @page: structure to page |
| * |
| */ |
| static int v9fs_fid_readpage(void *data, struct page *page) |
| { |
| struct p9_fid *fid = data; |
| 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, 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, v9fs_fid_readpage, |
| filp->private_data); |
| p9_debug(P9_DEBUG_VFS, " = %d\n", ret); |
| return ret; |
| } |
| |
| /** |
| * v9fs_release_page - release the private state associated with a page |
| * @page: The page to be released |
| * @gfp: The caller's allocation restrictions |
| * |
| * 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: The page to be invalidated |
| * @offset: offset of the invalidated region |
| * @length: length of the invalidated region |
| */ |
| |
| 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_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_SHIFT) |
| len = size & ~PAGE_MASK; |
| else |
| len = PAGE_SIZE; |
| |
| bvec.bv_page = page; |
| bvec.bv_offset = 0; |
| bvec.bv_len = len; |
| iov_iter_bvec(&from, 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 |
| * @page: The page to be cleaned up |
| * |
| * 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 |
| * @iter: The data/buffer to use |
| * |
| * 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) |
| { |
| struct file *file = iocb->ki_filp; |
| loff_t pos = iocb->ki_pos; |
| 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_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_SIZE) |
| goto out; |
| |
| retval = v9fs_fid_readpage(v9inode->writeback_fid, page); |
| put_page(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 (!PageUptodate(page)) { |
| if (unlikely(copied < len)) { |
| copied = 0; |
| goto out; |
| } else if (len == PAGE_SIZE) { |
| 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); |
| out: |
| unlock_page(page); |
| put_page(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, |
| }; |