From patchwork Mon Jun 20 20:15:35 2011 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Christoph Hellwig X-Patchwork-Id: 101196 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 26EA6B6F5D for ; Tue, 21 Jun 2011 06:21:14 +1000 (EST) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754758Ab1FTUUz (ORCPT ); Mon, 20 Jun 2011 16:20:55 -0400 Received: from 173-166-109-252-newengland.hfc.comcastbusiness.net ([173.166.109.252]:52961 "EHLO bombadil.infradead.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753275Ab1FTUUg (ORCPT ); Mon, 20 Jun 2011 16:20:36 -0400 Received: from hch by bombadil.infradead.org with local (Exim 4.76 #1 (Red Hat Linux)) id 1QYkxS-0007Ki-QD; Mon, 20 Jun 2011 20:20:30 +0000 Message-Id: <20110620202030.765939598@bombadil.infradead.org> User-Agent: quilt/0.48-1 Date: Mon, 20 Jun 2011 16:15:35 -0400 From: Christoph Hellwig To: viro@zeniv.linux.org.uk, tglx@linutronix.de Cc: linux-fsdevel@vger.kernel.org, linux-ext4@vger.kernel.org, linux-btrfs@vger.kernel.org, hirofumi@mail.parknet.co.jp, mfasheh@suse.com, jlbec@evilplan.org Subject: [PATCH 2/8] ext4: remove i_alloc_sem abuse References: <20110620201533.847236272@bombadil.infradead.org> Content-Disposition: inline; filename=ext4-introduce-truncate-mutex X-SRS-Rewrite: SMTP reverse-path rewritten from by bombadil.infradead.org See http://www.infradead.org/rpr.html Sender: linux-ext4-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-ext4@vger.kernel.org Add a new rw_semaphore to protect page_mkwrite against truncate. Previous i_alloc_sem was abused for this, but it's going away in this series. Signed-off-by: Christoph Hellwig --- To unsubscribe from this list: send the line "unsubscribe linux-ext4" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Index: linux-2.6/fs/ext4/inode.c =================================================================== --- linux-2.6.orig/fs/ext4/inode.c 2011-06-20 14:25:33.779248128 +0200 +++ linux-2.6/fs/ext4/inode.c 2011-06-20 14:27:53.025907745 +0200 @@ -5357,6 +5357,7 @@ int ext4_setattr(struct dentry *dentry, if (attr->ia_size > sbi->s_bitmap_maxbytes) return -EFBIG; } + down_write(&(EXT4_I(inode)->truncate_lock)); } if (S_ISREG(inode->i_mode) && @@ -5405,6 +5406,9 @@ int ext4_setattr(struct dentry *dentry, ext4_truncate(inode); } + if (attr->ia_valid & ATTR_SIZE) + up_write(&(EXT4_I(inode)->truncate_lock)); + if (!rc) { setattr_copy(inode, attr); mark_inode_dirty(inode); @@ -5850,10 +5854,10 @@ int ext4_page_mkwrite(struct vm_area_str struct address_space *mapping = inode->i_mapping; /* - * Get i_alloc_sem to stop truncates messing with the inode. We cannot - * get i_mutex because we are already holding mmap_sem. + * Get truncate_lock to stop truncates messing with the inode. We + * cannot get i_mutex because we are already holding mmap_sem. */ - down_read(&inode->i_alloc_sem); + down_read(&(EXT4_I(inode)->truncate_lock)); size = i_size_read(inode); if (page->mapping != mapping || size <= page_offset(page) || !PageUptodate(page)) { @@ -5865,7 +5869,7 @@ int ext4_page_mkwrite(struct vm_area_str lock_page(page); wait_on_page_writeback(page); if (PageMappedToDisk(page)) { - up_read(&inode->i_alloc_sem); + up_read(&(EXT4_I(inode)->truncate_lock)); return VM_FAULT_LOCKED; } @@ -5883,7 +5887,7 @@ int ext4_page_mkwrite(struct vm_area_str if (page_has_buffers(page)) { if (!walk_page_buffers(NULL, page_buffers(page), 0, len, NULL, ext4_bh_unmapped)) { - up_read(&inode->i_alloc_sem); + up_read(&(EXT4_I(inode)->truncate_lock)); return VM_FAULT_LOCKED; } } @@ -5912,11 +5916,11 @@ int ext4_page_mkwrite(struct vm_area_str */ lock_page(page); wait_on_page_writeback(page); - up_read(&inode->i_alloc_sem); + up_read(&(EXT4_I(inode)->truncate_lock)); return VM_FAULT_LOCKED; out_unlock: if (ret) ret = VM_FAULT_SIGBUS; - up_read(&inode->i_alloc_sem); + up_read(&(EXT4_I(inode)->truncate_lock)); return ret; } Index: linux-2.6/fs/ext4/super.c =================================================================== --- linux-2.6.orig/fs/ext4/super.c 2011-06-20 14:25:33.795914793 +0200 +++ linux-2.6/fs/ext4/super.c 2011-06-20 14:27:06.269243443 +0200 @@ -871,6 +871,7 @@ static struct inode *ext4_alloc_inode(st ei->i_datasync_tid = 0; atomic_set(&ei->i_ioend_count, 0); atomic_set(&ei->i_aiodio_unwritten, 0); + init_rwsem(&ei->truncate_lock); return &ei->vfs_inode; } Index: linux-2.6/fs/ext4/ext4.h =================================================================== --- linux-2.6.orig/fs/ext4/ext4.h 2011-06-20 14:25:33.752581461 +0200 +++ linux-2.6/fs/ext4/ext4.h 2011-06-20 14:27:06.272576777 +0200 @@ -844,6 +844,9 @@ struct ext4_inode_info { /* on-disk additional length */ __u16 i_extra_isize; + /* protect page_mkwrite against truncates */ + struct rw_semaphore truncate_lock; + #ifdef CONFIG_QUOTA /* quota space reservation, managed internally by quota code */ qsize_t i_reserved_quota;