From: Eric Sandeen Subject: Re: [PATCH] ext4: delayed allocation i_blocks fix for stat(2) Date: Mon, 07 Jul 2008 20:11:08 -0500 Message-ID: <4872BEAC.7010007@redhat.com> References: <1215473799.6702.9.camel@mingming-laptop> Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit Cc: linux-ext4@vger.kernel.org To: Mingming Cao Return-path: Received: from mx1.redhat.com ([66.187.233.31]:43126 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754679AbYGHBLL (ORCPT ); Mon, 7 Jul 2008 21:11:11 -0400 In-Reply-To: <1215473799.6702.9.camel@mingming-laptop> Sender: linux-ext4-owner@vger.kernel.org List-ID: Mingming Cao wrote: > ext4: delayed allocation i_blocks fix for stat(2) > > From: Mingming Cao > > Right now i_blocks is not getting updated until the disks are actually > allocaed on disk. This means with delayed allocation, right after files > are copied, "ls -sF" shoes the file as taking 0 blocks on disk. "du" > also shows the files taking zero space, which is highly confusing to the user. > > Since current delayed allocation already keep track of per-inode total number > of blocks that are subject to delayed allocation, this patch fix this by using > that to adjust the value returned by stat(2). When real block allocation > is done, the i_blocks will get updated. Since the reserved blocks for delayed > allocation will be decreased, this will be keep value returned by stat(2) > consistent. > > Signed-off-by: Mingming Cao Thanks Mingming, looks like just the right approach. Something about the spinlock for every stat seems heavy-handed to me but I'll have to give that more thought. :) -Eric > --- > fs/ext4/ext4.h | 2 ++ > fs/ext4/file.c | 1 + > fs/ext4/inode.c | 26 ++++++++++++++++++++++++++ > 3 files changed, 29 insertions(+) > > Index: linux-2.6.26-rc9/fs/ext4/ext4.h > =================================================================== > --- linux-2.6.26-rc9.orig/fs/ext4/ext4.h 2008-07-07 16:29:23.000000000 -0700 > +++ linux-2.6.26-rc9/fs/ext4/ext4.h 2008-07-07 16:32:54.000000000 -0700 > @@ -1059,6 +1059,8 @@ int ext4_get_blocks_handle(handle_t *han > extern struct inode *ext4_iget(struct super_block *, unsigned long); > extern int ext4_write_inode (struct inode *, int); > extern int ext4_setattr (struct dentry *, struct iattr *); > +extern int ext4_getattr(struct vfsmount *mnt, struct dentry *dentry, > + struct kstat *stat); > extern void ext4_delete_inode (struct inode *); > extern int ext4_sync_inode (handle_t *, struct inode *); > extern void ext4_discard_reservation (struct inode *); > Index: linux-2.6.26-rc9/fs/ext4/file.c > =================================================================== > --- linux-2.6.26-rc9.orig/fs/ext4/file.c 2008-07-07 16:29:21.000000000 -0700 > +++ linux-2.6.26-rc9/fs/ext4/file.c 2008-07-07 16:29:51.000000000 -0700 > @@ -161,6 +161,7 @@ const struct file_operations ext4_file_o > const struct inode_operations ext4_file_inode_operations = { > .truncate = ext4_truncate, > .setattr = ext4_setattr, > + .getattr = ext4_getattr, > #ifdef CONFIG_EXT4DEV_FS_XATTR > .setxattr = generic_setxattr, > .getxattr = generic_getxattr, > Index: linux-2.6.26-rc9/fs/ext4/inode.c > =================================================================== > --- linux-2.6.26-rc9.orig/fs/ext4/inode.c 2008-07-07 16:29:22.000000000 -0700 > +++ linux-2.6.26-rc9/fs/ext4/inode.c 2008-07-07 16:31:13.000000000 -0700 > @@ -4203,6 +4203,32 @@ err_out: > return error; > } > > +int ext4_getattr(struct vfsmount *mnt, struct dentry *dentry, > + struct kstat *stat) > +{ > + struct inode *inode; > + unsigned long delalloc_blocks; > + > + inode = dentry->d_inode; > + generic_fillattr(inode, stat); > + > + /* > + * We can't update i_blocks if the block allocation is delayed > + * otherwise in the case of system crash before the real block > + * allocation is done, we will have i_blocks inconsistent with > + * on-disk file blocks. > + * We always keep i_blocks updated together with real > + * allocation. But to not confuse with user, stat > + * will return the blocks that include the delayed allocation > + * blocks for this file. > + */ > + spin_lock(&EXT4_I(inode)->i_block_reservation_lock); > + delalloc_blocks = EXT4_I(inode)->i_reserved_data_blocks; > + spin_unlock(&EXT4_I(inode)->i_block_reservation_lock); > + > + stat->blocks += (delalloc_blocks << inode->i_sb->s_blocksize_bits)>>9; > + return 0; > +} > > /* > * How many blocks doth make a writepage()? > > > -- > 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