From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from relay.sgi.com (relay1.corp.sgi.com [137.38.102.111]) by oss.sgi.com (Postfix) with ESMTP id D5DA17F6B for ; Wed, 1 Oct 2014 18:23:40 -0500 (CDT) Received: from cuda.sgi.com (cuda3.sgi.com [192.48.176.15]) by relay1.corp.sgi.com (Postfix) with ESMTP id B8B208F8037 for ; Wed, 1 Oct 2014 16:23:40 -0700 (PDT) Received: from ipmail07.adl2.internode.on.net (ipmail07.adl2.internode.on.net [150.101.137.131]) by cuda.sgi.com with ESMTP id ICznqigctrQ5bm0m for ; Wed, 01 Oct 2014 16:23:39 -0700 (PDT) Date: Thu, 2 Oct 2014 09:23:25 +1000 From: Dave Chinner Subject: Re: [PATCH] xfs: check for inode size overflow in xfs_new_eof() Message-ID: <20141001232325.GF10298@dastard> References: <1412104883-6151-1-git-send-email-bfoster@redhat.com> MIME-Version: 1.0 Content-Disposition: inline In-Reply-To: <1412104883-6151-1-git-send-email-bfoster@redhat.com> List-Id: XFS Filesystem from SGI List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Errors-To: xfs-bounces@oss.sgi.com Sender: xfs-bounces@oss.sgi.com To: Brian Foster Cc: xfs@oss.sgi.com On Tue, Sep 30, 2014 at 03:21:23PM -0400, Brian Foster wrote: > If we write to the maximum file offset (2^63-2), XFS fails to log the > inode size update when the page is flushed. For example: > > $ xfs_io -fc "pwrite `echo "2^63-1-1" | bc` 1" /mnt/file > wrote 1/1 bytes at offset 9223372036854775806 > 1.000000 bytes, 1 ops; 0.0000 sec (22.711 KiB/sec and 23255.8140 ops/sec) > $ stat -c %s /mnt/file > 9223372036854775807 > $ umount /mnt ; mount /mnt/ > $ stat -c %s /mnt/file > 0 > > This occurs because XFS calculates the new file size as io_offset + > io_size, I/O occurs in block sized requests, and the maximum supported > file size is not block aligned. Therefore, a write to the max allowable > offset on a 4k blocksize fs results in a write of size 4k to offset > 2^63-4096 (e.g., equivalent to round_down(2^63-1, 4096), or IOW the > offset of the block that contains the max file size). The offset plus > size calculation (2^63 - 4096 + 4096 == 2^63) overflows the signed > 64-bit variable which goes negative and causes the > comparison to the > on-disk inode size to fail. This returns 0 from xfs_new_eof() and > results in no change to the inode on-disk. > > Update xfs_new_eof() to explicitly detect overflow of the local > calculation and use the VFS inode size in this scenario. The VFS inode > size is capped to the maximum and thus XFS writes the correct inode size > to disk. > > Signed-off-by: Brian Foster > --- > > Hi all, > > This was also discovered while playing around with xfs/071, though it > doesn't cause a failure. FWIW, I started off fixing this by converting > xfs_new_eof() to use xfs_ufsize_t. That worked, but this seemed more > explicit. > > Brian > > fs/xfs/xfs_inode.h | 2 +- > 1 file changed, 1 insertion(+), 1 deletion(-) > > diff --git a/fs/xfs/xfs_inode.h b/fs/xfs/xfs_inode.h > index c10e3fa..9af2882 100644 > --- a/fs/xfs/xfs_inode.h > +++ b/fs/xfs/xfs_inode.h > @@ -102,7 +102,7 @@ xfs_new_eof(struct xfs_inode *ip, xfs_fsize_t new_size) > { > xfs_fsize_t i_size = i_size_read(VFS_I(ip)); > > - if (new_size > i_size) > + if (new_size > i_size || new_size < 0) > new_size = i_size; > return new_size > ip->i_d.di_size ? new_size : 0; > } Looks good. Reviewed-by: Dave Chinner -- Dave Chinner david@fromorbit.com _______________________________________________ xfs mailing list xfs@oss.sgi.com http://oss.sgi.com/mailman/listinfo/xfs