From mboxrd@z Thu Jan 1 00:00:00 1970 From: OGAWA Hirofumi Subject: Re: [PATCH RESEND v5] fat: editions to support fat_fallocate Date: Mon, 29 Apr 2013 23:31:33 +0900 Message-ID: <87ppxd4ddm.fsf@devron.myhome.or.jp> References: <1367107703-2665-1-git-send-email-linkinjeon@gmail.com> Mime-Version: 1.0 Content-Type: text/plain Cc: akpm@linux-foundation.org, linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org, Namjae Jeon , Amit Sahrawat To: Namjae Jeon Return-path: In-Reply-To: <1367107703-2665-1-git-send-email-linkinjeon@gmail.com> (Namjae Jeon's message of "Sun, 28 Apr 2013 09:08:23 +0900") Sender: linux-kernel-owner@vger.kernel.org List-Id: linux-fsdevel.vger.kernel.org Namjae Jeon writes: I couldn't review fully though. > + if (mmu_private_ideal < MSDOS_I(inode)->mmu_private && > + filp->f_dentry->d_count == 1) > + fat_truncate_blocks(inode, inode->i_size); Hm, why d_count == 1 check is needed? Feel strange and racy. > + /* Start the allocation.We are not zeroing out the clusters */ > + while (nr_cluster-- > 0) { > + err = fat_alloc_clusters(inode, &cluster, 1); Why doesn't allocate clusters at once by fat_alloc_clusters()? > + size = i_size_read(inode); > + mmu_private_actual = MSDOS_I(inode)->mmu_private; > + mmu_private_ideal = round_up(size, sb->s_blocksize); > + if ((mmu_private_actual > mmu_private_ideal) && (pos > size)) { > + err = fat_zero_falloc_area(file, mapping, pos); > + if (err) { > + fat_msg(sb, KERN_ERR, > + "Error (%d) zeroing fallocated area", err); > + return err; > + } > + } This way probably inefficient. This would write data twice times (one is zeroed, one is actual data). So, cpu time would be twice higher if user uses fallocated, right? Difference of fallocated area would be whether get_block() set buffer_new() or not? If true, we should change get_block(), not write_begin()? Thanks. -- OGAWA Hirofumi