From: Sunil Mushran Subject: Re: [PATCH 1/3] fs: add SEEK_HOLE and SEEK_DATA flags V4 Date: Wed, 25 May 2011 15:07:23 -0700 Message-ID: <4DDD7D9B.3060701@oracle.com> References: <1306186991-1905-1-git-send-email-josef@redhat.com> <0E7B812A-4057-4EB8-93F5-79ED9FCE2CCD@dilger.ca> <4DDD6AB9.3030906@redhat.com> Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Cc: Andreas Dilger , linux-fsdevel@vger.kernel.org, linux-btrfs@vger.kernel.org, linux-kernel@vger.kernel.org, linux-ext4@vger.kernel.org, viro@ZenIV.linux.org.uk To: Josef Bacik Return-path: Received: from rcsinet10.oracle.com ([148.87.113.121]:61561 "EHLO rcsinet10.oracle.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751743Ab1EYWHq (ORCPT ); Wed, 25 May 2011 18:07:46 -0400 In-Reply-To: <4DDD6AB9.3030906@redhat.com> Sender: linux-ext4-owner@vger.kernel.org List-ID: On 05/25/2011 01:46 PM, Josef Bacik wrote: > On 05/25/2011 03:45 PM, Andreas Dilger wrote: >> Most of the filesystem-specific ->llseek() methods don't do any error >> checking on "origin" because this is handled at the sys_llseek() level, >> and hasn't changed in many years. >> >> I assume this patch is also dependent upon the "remove default_llseek()" >> patch, so that the implementation of SEEK_DATA and SEEK_HOLE can be done >> in only generic_file_llseek()? >> >> Finally, while looking through the various ->llseek() methods I notice >> that many filesystems return "i_size" for SEEK_END, which clearly does >> not make sense for filesystems like ext3/ext4 htree, btrfs, etc that >> use hash keys instead of byte offsets for doing directory traversal. >> The comment at generic_file_llseek() is that it is intended for use by >> regular files. >> >> Should the ext4_llseek() code be changed to return 0x7ffffffff for the >> SEEK_END value? That makes more sense compared to values returned for >> SEEK_CUR so that an application can compare the current "offset" with >> the final value for a progress bar. > So maybe we make SEEK_DATA/SEEK_HOLE only work on regular files and not > directories? Sunil what does solaris do? Thanks, In Solaris the size of the directory appears to be equal to the number of entries and the offset is the file#, so to speak. SEEK_DATA returns the current offset and SEEK_HOLE the last one. Just to be clear, I am not a Solaris expert. I just happen to have access to it. ;)