From patchwork Fri Jun 29 10:56:03 2012 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Lukas Czerner X-Patchwork-Id: 168037 Return-Path: X-Original-To: patchwork-incoming@ozlabs.org Delivered-To: patchwork-incoming@ozlabs.org Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by ozlabs.org (Postfix) with ESMTP id 52318B6FD9 for ; Fri, 29 Jun 2012 20:56:56 +1000 (EST) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753093Ab2F2K4W (ORCPT ); Fri, 29 Jun 2012 06:56:22 -0400 Received: from mx1.redhat.com ([209.132.183.28]:36245 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751652Ab2F2K4V (ORCPT ); Fri, 29 Jun 2012 06:56:21 -0400 Received: from int-mx11.intmail.prod.int.phx2.redhat.com (int-mx11.intmail.prod.int.phx2.redhat.com [10.5.11.24]) by mx1.redhat.com (8.14.4/8.14.4) with ESMTP id q5TAuIco009680 (version=TLSv1/SSLv3 cipher=DHE-RSA-AES256-SHA bits=256 verify=OK); Fri, 29 Jun 2012 06:56:18 -0400 Received: from vpn-9-37.rdu.redhat.com (vpn-9-37.rdu.redhat.com [10.11.9.37]) by int-mx11.intmail.prod.int.phx2.redhat.com (8.14.4/8.14.4) with ESMTP id q5TAuFT8006949; Fri, 29 Jun 2012 06:56:16 -0400 From: Lukas Czerner To: linux-ext4@vger.kernel.org Cc: linux-fsdevel@vger.kernel.org, tytso@mit.edu, achender@linux.vnet.ibm.com, Lukas Czerner Subject: [PATCH 1/8] Revert "ext4: remove no longer used functions in inode.c" Date: Fri, 29 Jun 2012 12:56:03 +0200 Message-Id: <1340967370-13728-1-git-send-email-lczerner@redhat.com> X-Scanned-By: MIMEDefang 2.68 on 10.5.11.24 Sender: linux-ext4-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-ext4@vger.kernel.org This reverts commit ccb4d7af914e0fe9b2f1022f8ea6c300463fd5e6. This commit reintroduces functions ext4_block_truncate_page() and ext4_block_zero_page_range() which has been previously removed in favour of ext4_discard_partial_page_buffers(). In future commits we want to reintroduce those function and remove ext4_discard_partial_page_buffers() since it is duplicating some code and also partially duplicating work of truncate_pagecache_range(), moreover the old implementation was much clearer. Signed-off-by: Lukas Czerner --- fs/ext4/ext4.h | 4 ++ fs/ext4/inode.c | 120 +++++++++++++++++++++++++++++++++++++++++++++++++++++++ 2 files changed, 124 insertions(+), 0 deletions(-) diff --git a/fs/ext4/ext4.h b/fs/ext4/ext4.h index cfc4e01..439af1e 100644 --- a/fs/ext4/ext4.h +++ b/fs/ext4/ext4.h @@ -1995,6 +1995,10 @@ extern int ext4_alloc_da_blocks(struct inode *inode); extern void ext4_set_aops(struct inode *inode); extern int ext4_writepage_trans_blocks(struct inode *); extern int ext4_chunk_trans_blocks(struct inode *, int nrblocks); +extern int ext4_block_truncate_page(handle_t *handle, + struct address_space *mapping, loff_t from); +extern int ext4_block_zero_page_range(handle_t *handle, + struct address_space *mapping, loff_t from, loff_t length); extern int ext4_discard_partial_page_buffers(handle_t *handle, struct address_space *mapping, loff_t from, loff_t length, int flags); diff --git a/fs/ext4/inode.c b/fs/ext4/inode.c index 02bc8cb..588f9fa 100644 --- a/fs/ext4/inode.c +++ b/fs/ext4/inode.c @@ -3381,6 +3381,126 @@ next: return err; } +/* + * ext4_block_truncate_page() zeroes out a mapping from file offset `from' + * up to the end of the block which corresponds to `from'. + * This required during truncate. We need to physically zero the tail end + * of that block so it doesn't yield old data if the file is later grown. + */ +int ext4_block_truncate_page(handle_t *handle, + struct address_space *mapping, loff_t from) +{ + unsigned offset = from & (PAGE_CACHE_SIZE-1); + unsigned length; + unsigned blocksize; + struct inode *inode = mapping->host; + + blocksize = inode->i_sb->s_blocksize; + length = blocksize - (offset & (blocksize - 1)); + + return ext4_block_zero_page_range(handle, mapping, from, length); +} + +/* + * ext4_block_zero_page_range() zeros out a mapping of length 'length' + * starting from file offset 'from'. The range to be zero'd must + * be contained with in one block. If the specified range exceeds + * the end of the block it will be shortened to end of the block + * that cooresponds to 'from' + */ +int ext4_block_zero_page_range(handle_t *handle, + struct address_space *mapping, loff_t from, loff_t length) +{ + ext4_fsblk_t index = from >> PAGE_CACHE_SHIFT; + unsigned offset = from & (PAGE_CACHE_SIZE-1); + unsigned blocksize, max, pos; + ext4_lblk_t iblock; + struct inode *inode = mapping->host; + struct buffer_head *bh; + struct page *page; + int err = 0; + + page = find_or_create_page(mapping, from >> PAGE_CACHE_SHIFT, + mapping_gfp_mask(mapping) & ~__GFP_FS); + if (!page) + return -ENOMEM; + + blocksize = inode->i_sb->s_blocksize; + max = blocksize - (offset & (blocksize - 1)); + + /* + * correct length if it does not fall between + * 'from' and the end of the block + */ + if (length > max || length < 0) + length = max; + + iblock = index << (PAGE_CACHE_SHIFT - inode->i_sb->s_blocksize_bits); + + if (!page_has_buffers(page)) + create_empty_buffers(page, blocksize, 0); + + /* Find the buffer that contains "offset" */ + bh = page_buffers(page); + pos = blocksize; + while (offset >= pos) { + bh = bh->b_this_page; + iblock++; + pos += blocksize; + } + + err = 0; + if (buffer_freed(bh)) { + BUFFER_TRACE(bh, "freed: skip"); + goto unlock; + } + + if (!buffer_mapped(bh)) { + BUFFER_TRACE(bh, "unmapped"); + ext4_get_block(inode, iblock, bh, 0); + /* unmapped? It's a hole - nothing to do */ + if (!buffer_mapped(bh)) { + BUFFER_TRACE(bh, "still unmapped"); + goto unlock; + } + } + + /* Ok, it's mapped. Make sure it's up-to-date */ + if (PageUptodate(page)) + set_buffer_uptodate(bh); + + if (!buffer_uptodate(bh)) { + err = -EIO; + ll_rw_block(READ, 1, &bh); + wait_on_buffer(bh); + /* Uhhuh. Read error. Complain and punt. */ + if (!buffer_uptodate(bh)) + goto unlock; + } + + if (ext4_should_journal_data(inode)) { + BUFFER_TRACE(bh, "get write access"); + err = ext4_journal_get_write_access(handle, bh); + if (err) + goto unlock; + } + + zero_user(page, offset, length); + + BUFFER_TRACE(bh, "zeroed end of block"); + + err = 0; + if (ext4_should_journal_data(inode)) { + err = ext4_handle_dirty_metadata(handle, inode, bh); + } else + mark_buffer_dirty(bh); + +unlock: + unlock_page(page); + page_cache_release(page); + return err; +} + int ext4_can_truncate(struct inode *inode) { if (S_ISREG(inode->i_mode))