From: Christoph Hellwig Subject: [PATCH 1/8] far: remove i_alloc_sem abuse Date: Mon, 20 Jun 2011 16:15:34 -0400 Message-ID: <20110620202030.577464178@bombadil.infradead.org> References: <20110620201533.847236272@bombadil.infradead.org> 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 To: viro@zeniv.linux.org.uk, tglx@linutronix.de Return-path: Received: from 173-166-109-252-newengland.hfc.comcastbusiness.net ([173.166.109.252]:52960 "EHLO bombadil.infradead.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753286Ab1FTUUg (ORCPT ); Mon, 20 Jun 2011 16:20:36 -0400 Content-Disposition: inline; filename=fat-avoid-i_alloc_sem Sender: linux-ext4-owner@vger.kernel.org List-ID: Add a new rw_semaphore to protect bmap against truncate. Previous i_alloc_sem was abused for this, but it's going away in this series. Signed-off-by: Christoph Hellwig Index: linux-2.6/fs/fat/inode.c =================================================================== --- linux-2.6.orig/fs/fat/inode.c 2011-06-20 21:28:19.707963855 +0200 +++ linux-2.6/fs/fat/inode.c 2011-06-20 21:29:25.031293882 +0200 @@ -224,9 +224,9 @@ static sector_t _fat_bmap(struct address sector_t blocknr; /* fat_get_cluster() assumes the requested blocknr isn't truncated. */ - down_read(&mapping->host->i_alloc_sem); + down_read(&MSDOS_I(mapping->host)->truncate_lock); blocknr = generic_block_bmap(mapping, block, fat_get_block); - up_read(&mapping->host->i_alloc_sem); + up_read(&MSDOS_I(mapping->host)->truncate_lock); return blocknr; } @@ -510,6 +510,8 @@ static struct inode *fat_alloc_inode(str ei = kmem_cache_alloc(fat_inode_cachep, GFP_NOFS); if (!ei) return NULL; + + init_rwsem(&ei->truncate_lock); return &ei->vfs_inode; } Index: linux-2.6/fs/fat/fat.h =================================================================== --- linux-2.6.orig/fs/fat/fat.h 2011-06-20 21:28:19.724630522 +0200 +++ linux-2.6/fs/fat/fat.h 2011-06-20 21:29:25.034627215 +0200 @@ -109,6 +109,7 @@ struct msdos_inode_info { int i_attrs; /* unused attribute bits */ loff_t i_pos; /* on-disk position of directory entry or 0 */ struct hlist_node i_fat_hash; /* hash by i_location */ + struct rw_semaphore truncate_lock; /* protect bmap against truncate */ struct inode vfs_inode; }; Index: linux-2.6/fs/fat/file.c =================================================================== --- linux-2.6.orig/fs/fat/file.c 2011-06-20 21:28:19.744630521 +0200 +++ linux-2.6/fs/fat/file.c 2011-06-20 21:29:54.501292390 +0200 @@ -429,8 +429,10 @@ int fat_setattr(struct dentry *dentry, s } if (attr->ia_valid & ATTR_SIZE) { + down_write(&MSDOS_I(inode)->truncate_lock); truncate_setsize(inode, attr->ia_size); fat_truncate_blocks(inode, attr->ia_size); + up_write(&MSDOS_I(inode)->truncate_lock); } setattr_copy(inode, attr);