From: "Sandeep K Sinha" Subject: Re: Copying Data Blocks Date: Mon, 12 Jan 2009 12:26:42 +0530 Message-ID: <37d33d830901112256g4aecafc0h9e5cdb08f268e6ab@mail.gmail.com> References: <2d08ef090901060236p46d4d396x797e4bceb24a2a34@mail.gmail.com> <804dabb00901110715x2baf84e8kc0fc5d6fa2512fe8@mail.gmail.com> <2d08ef090901112218v1c6820d7q98d39af1350a07a0@mail.gmail.com> Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit Cc: "Peter Teoh" , ext4 , Kernelnewbies To: "Rohit Sharma" Return-path: Received: from wa-out-1112.google.com ([209.85.146.177]:60357 "EHLO wa-out-1112.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752081AbZALG4n (ORCPT ); Mon, 12 Jan 2009 01:56:43 -0500 Received: by wa-out-1112.google.com with SMTP id v27so5520498wah.21 for ; Sun, 11 Jan 2009 22:56:42 -0800 (PST) In-Reply-To: <2d08ef090901112218v1c6820d7q98d39af1350a07a0@mail.gmail.com> Content-Disposition: inline Sender: linux-ext4-owner@vger.kernel.org List-ID: Hi Rohit, On Mon, Jan 12, 2009 at 11:48 AM, Rohit Sharma wrote: > Hi, > > I am having some issues in locking inode while copying data blocks. > We are trying to keep file system live during this operation, so > both read and write operations should work. > In this case what type of lock on inode should be used, semaphore, > mutex or spinlock? > Now here you need to do some homework first. Each of the locks have its own meaning and particular uses cases. The current inode struct has the following locks: 1. i_lock 2. i_alloc_sem 3. i_mutex 4. i_flock 646 spinlock_t i_lock; /* i_blocks, i_bytes, maybe i_size */ 647 struct mutex i_mutex; 648 struct rw_semaphore i_alloc_sem; 649 const struct inode_operations *i_op; 650 const struct file_operations *i_fop; /* former ->i_op->default_file_ops */ 651 struct super_block *i_sb; 652 struct file_lock *i_flock; Read the difference between spinlock, mutex, and semaphore. You will be able to understand the semantics of each of these. > > On Sun, Jan 11, 2009 at 8:45 PM, Peter Teoh wrote: >> Sorry.....some mistakes...a resent: >> >> Here are some tips on the blockdevice API: >> >> http://lkml.org/lkml/2006/1/24/287 >> http://linux.derkeiler.com/Mailing-Lists/Kernel/2006-01/msg09388.html >> >> as indicated, documentation is rather sparse in this area. >> >> not sure if anyone else have a summary list of blockdevice API and its >> explanation? >> >> not wrt the following "cleanup patch", i am not sure how the API will change: >> >> http://lwn.net/Articles/304485/ >> >> thanks. >> >> On Tue, Jan 6, 2009 at 6:36 PM, Rohit Sharma wrote: >>> >>> I want to read data blocks from one inode >>> and copy it to other inode. >>> >>> I mean to copy data from data blocks associated with one inode >>> to the data blocks associated with other inode. >>> >>> Is that possible in kernel space.? >>> -- >> >> >> >> -- >> Regards, >> Peter Teoh >> > > -- > 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."