From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752929Ab3F2Rox (ORCPT ); Sat, 29 Jun 2013 13:44:53 -0400 Received: from relay.parallels.com ([195.214.232.42]:51669 "EHLO relay.parallels.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752643Ab3F2Rov (ORCPT ); Sat, 29 Jun 2013 13:44:51 -0400 Subject: [PATCH 06/16] fuse: Trust kernel i_size only - v4 To: miklos@szeredi.hu From: Maxim Patlasov Cc: riel@redhat.com, dev@parallels.com, xemul@parallels.com, fuse-devel@lists.sourceforge.net, bfoster@redhat.com, linux-kernel@vger.kernel.org, jbottomley@parallels.com, linux-mm@kvack.org, viro@zeniv.linux.org.uk, linux-fsdevel@vger.kernel.org, akpm@linux-foundation.org, fengguang.wu@intel.com, devel@openvz.org, mgorman@suse.de Date: Sat, 29 Jun 2013 21:44:40 +0400 Message-ID: <20130629174304.20175.84433.stgit@maximpc.sw.ru> In-Reply-To: <20130629172211.20175.70154.stgit@maximpc.sw.ru> References: <20130629172211.20175.70154.stgit@maximpc.sw.ru> User-Agent: StGit/0.15 MIME-Version: 1.0 Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: Pavel Emelyanov Make fuse think that when writeback is on the inode's i_size is always up-to-date and not update it with the value received from the userspace. This is done because the page cache code may update i_size without letting the FS know. This assumption implies fixing the previously introduced short-read helper -- when a short read occurs the 'hole' is filled with zeroes. fuse_file_fallocate() is also fixed because now we should keep i_size up to date, so it must be updated if FUSE_FALLOCATE request succeeded. Changed in v2: - improved comment in fuse_short_read() - fixed fuse_file_fallocate() for KEEP_SIZE mode Changed in v3: - fixed fuse_fillattr() not to use local i_size if writeback-cache is off - added a comment explaining why we cannot trust attr.size from server Changed in v4: - do not change fuse_file_fallocate() because what we need is already implemented in commits a200a2d and 14c1441 Signed-off-by: Maxim V. Patlasov --- fs/fuse/dir.c | 13 +++++++++++-- fs/fuse/file.c | 26 ++++++++++++++++++++++++-- fs/fuse/inode.c | 11 +++++++++-- 3 files changed, 44 insertions(+), 6 deletions(-) diff --git a/fs/fuse/dir.c b/fs/fuse/dir.c index f3f783d..b755884 100644 --- a/fs/fuse/dir.c +++ b/fs/fuse/dir.c @@ -851,6 +851,11 @@ static void fuse_fillattr(struct inode *inode, struct fuse_attr *attr, struct kstat *stat) { unsigned int blkbits; + struct fuse_conn *fc = get_fuse_conn(inode); + + /* see the comment in fuse_change_attributes() */ + if (fc->writeback_cache && S_ISREG(inode->i_mode)) + attr->size = i_size_read(inode); stat->dev = inode->i_sb->s_dev; stat->ino = attr->ino; @@ -1576,6 +1581,7 @@ int fuse_do_setattr(struct inode *inode, struct iattr *attr, struct fuse_setattr_in inarg; struct fuse_attr_out outarg; bool is_truncate = false; + bool is_wb = fc->writeback_cache; loff_t oldsize; int err; @@ -1645,7 +1651,9 @@ int fuse_do_setattr(struct inode *inode, struct iattr *attr, fuse_change_attributes_common(inode, &outarg.attr, attr_timeout(&outarg)); oldsize = inode->i_size; - i_size_write(inode, outarg.attr.size); + /* see the comment in fuse_change_attributes() */ + if (!is_wb || is_truncate || !S_ISREG(inode->i_mode)) + i_size_write(inode, outarg.attr.size); if (is_truncate) { /* NOTE: this may release/reacquire fc->lock */ @@ -1657,7 +1665,8 @@ int fuse_do_setattr(struct inode *inode, struct iattr *attr, * Only call invalidate_inode_pages2() after removing * FUSE_NOWRITE, otherwise fuse_launder_page() would deadlock. */ - if (S_ISREG(inode->i_mode) && oldsize != outarg.attr.size) { + if ((is_truncate || !is_wb) && + S_ISREG(inode->i_mode) && oldsize != outarg.attr.size) { truncate_pagecache(inode, oldsize, outarg.attr.size); invalidate_inode_pages2(inode->i_mapping); } diff --git a/fs/fuse/file.c b/fs/fuse/file.c index 90fb235..98bc0d0 100644 --- a/fs/fuse/file.c +++ b/fs/fuse/file.c @@ -658,9 +658,31 @@ static void fuse_short_read(struct fuse_req *req, struct inode *inode, u64 attr_ver) { size_t num_read = req->out.args[0].size; + struct fuse_conn *fc = get_fuse_conn(inode); + + if (fc->writeback_cache) { + /* + * A hole in a file. Some data after the hole are in page cache, + * but have not reached the client fs yet. So, the hole is not + * present there. + */ + int i; + int start_idx = num_read >> PAGE_CACHE_SHIFT; + size_t off = num_read & (PAGE_CACHE_SIZE - 1); + + for (i = start_idx; i < req->num_pages; i++) { + struct page *page = req->pages[i]; + void *mapaddr = kmap_atomic(page); - loff_t pos = page_offset(req->pages[0]) + num_read; - fuse_read_update_size(inode, pos, attr_ver); + memset(mapaddr + off, 0, PAGE_CACHE_SIZE - off); + + kunmap_atomic(mapaddr); + off = 0; + } + } else { + loff_t pos = page_offset(req->pages[0]) + num_read; + fuse_read_update_size(inode, pos, attr_ver); + } } static int fuse_readpage(struct file *file, struct page *page) diff --git a/fs/fuse/inode.c b/fs/fuse/inode.c index 9a0cdde..121638d 100644 --- a/fs/fuse/inode.c +++ b/fs/fuse/inode.c @@ -197,6 +197,7 @@ void fuse_change_attributes(struct inode *inode, struct fuse_attr *attr, { struct fuse_conn *fc = get_fuse_conn(inode); struct fuse_inode *fi = get_fuse_inode(inode); + bool is_wb = fc->writeback_cache; loff_t oldsize; struct timespec old_mtime; @@ -210,10 +211,16 @@ void fuse_change_attributes(struct inode *inode, struct fuse_attr *attr, fuse_change_attributes_common(inode, attr, attr_valid); oldsize = inode->i_size; - i_size_write(inode, attr->size); + /* + * In case of writeback_cache enabled, the cached writes beyond EOF + * extend local i_size without keeping userspace server in sync. So, + * attr->size coming from server can be stale. We cannot trust it. + */ + if (!is_wb || !S_ISREG(inode->i_mode)) + i_size_write(inode, attr->size); spin_unlock(&fc->lock); - if (S_ISREG(inode->i_mode)) { + if (!is_wb && S_ISREG(inode->i_mode)) { bool inval = false; if (oldsize != attr->size) {