From: "Sandeep K Sinha" Subject: Re: ext2_block_alloc_info Date: Sun, 21 Dec 2008 01:10:47 +0530 Message-ID: <37d33d830812201140r1bc64a83kdc3f27b3fa88cc1b@mail.gmail.com> References: <2d08ef090812200743o47cd4abdwd9915653f6f4f3f7@mail.gmail.com> Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit Cc: Kernelnewbies , ext4 To: "Rohit Sharma" Return-path: Received: from rv-out-0506.google.com ([209.85.198.227]:7782 "EHLO rv-out-0506.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752816AbYLTTks (ORCPT ); Sat, 20 Dec 2008 14:40:48 -0500 Received: by rv-out-0506.google.com with SMTP id k40so1386551rvb.1 for ; Sat, 20 Dec 2008 11:40:47 -0800 (PST) In-Reply-To: <2d08ef090812200743o47cd4abdwd9915653f6f4f3f7@mail.gmail.com> Content-Disposition: inline Sender: linux-ext4-owner@vger.kernel.org List-ID: Hi Rohit, On Sat, Dec 20, 2008 at 9:13 PM, Rohit Sharma wrote: > A little confusion. > > Just refer this structure in linux/ext2_fs_sb.h > > struct ext2_block_alloc_info { > 46 /* information about reservation window */ > 47 struct ext2_reserve_window_node rsv_window_node; > 48 /* > 49 * was i_next_alloc_block in ext2_inode_info > 50 * is the logical (file-relative) number of the > 51 * most-recently-allocated block in this file. > 52 * We use this for detecting linearly ascending allocation requests. > 53 */ > 54 __u32 last_alloc_logical_block; > 55 /* > 56 * Was i_next_alloc_goal in ext2_inode_info > 57 * is the *physical* companion to i_next_alloc_block. > 58 * it the the physical block number of the block which was > most-recentl > 59 * allocated to this file. This give us the goal (target) > for the next Look at the comment, this clearly suggests that its a file specific information. So, its specific to inode. > 60 * allocation when we detect linearly ascending requests. > 61 */ It can be only to a file, as for the file system it is already ascending. > 62 ext2_fsblk_t last_alloc_physical_block; > 63}; > > > this information is maintained by ext2 for every inode. > > here last_alloc_logical_block is for every inode or its for filesystem. > inode. > I mean if we are allocating blocks for inode > it can be block no. 0 to n logically > and physically like 23 24 25 34 36 40 41 42 > > i mean to say > > is it like > > inode1 has logical blocks 1 2 3 , physical 22 23 24 > inode2 has logical blocks 4 5 6 , physical 34 35 50 > This is correct. > OR > > inode1 has logical blocks 0 1 2 , physical 22 23 24 > inode2 has logical blocks 0 1 2 , physical 34 35 50 > You cannot have the same logical block assigned to two inodes with diff physical blocks, probably. Doesn't make sense to me. > ?? > > -- > To unsubscribe from this list: send an email with > "unsubscribe kernelnewbies" to ecartis@nl.linux.org > Please read the FAQ at http://kernelnewbies.org/FAQ > > -- Regards, Sandeep. "To learn is to change. Education is a process that changes the learner."