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Fri, 21 Feb 2020 19:44:32 +0000 To: Matthew Wilcox References: <20200219210103.32400-1-willy@infradead.org> <20200219210103.32400-12-willy@infradead.org> <20200221153537.GE24185@bombadil.infradead.org> From: John Hubbard X-Nvconfidentiality: public Message-ID: <1fd052ce-cd5e-60ce-e494-cbf6427d3ed3@nvidia.com> Date: Fri, 21 Feb 2020 11:41:28 -0800 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:68.0) Gecko/20100101 Thunderbird/68.5.0 MIME-Version: 1.0 In-Reply-To: <20200221153537.GE24185@bombadil.infradead.org> X-Originating-IP: [10.124.1.5] X-ClientProxiedBy: HQMAIL101.nvidia.com (172.20.187.10) To HQMAIL107.nvidia.com (172.20.187.13) Content-Language: en-US DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=nvidia.com; s=n1; t=1582314258; bh=pQKOwwEmNmp5lZ+eX1Ols5QNnW+OORTLQJDMCsPxtEc=; h=X-PGP-Universal:Subject:To:CC:References:From:X-Nvconfidentiality: Message-ID:Date:User-Agent:MIME-Version:In-Reply-To: X-Originating-IP:X-ClientProxiedBy:Content-Type:Content-Language: Content-Transfer-Encoding; b=lYdo4NH8M7SXphPat6doJg0oOA1V6kLXukQ7JIEh5FVkfFb0/CxKOhHQdMiRNYy87 Q6EhPR2Fph1xqpiZaGm+fIV8Ra4pJE8E5H2Ofj6LlTy0+Qb+/+y64EhZcbjIYXrOqI IXR7s2kX4Yi3hnWXNuj2sU2+Joh83jXJxvw8pHXSeKQS/7ccswnLmpLkros2lxWTg/ 2U8B/Ar6NYNMOQFqfCj3j5XpjUwSHVdi0BMHCh2YVMnazsUm42RddLEt+ZRAKHCaXa IlYO+1WyQ2QxlFvwnZy2R5xtgMwusy7sT9ZlwHQi2bqndUATGT9KLiH14aMZETjP0i ow4Jt857PEIiA== X-Headers-End: 1j5EE5-00D0Xt-V0 Subject: Re: [f2fs-dev] [PATCH v7 11/24] mm: Move end_index check out of readahead loop X-BeenThere: linux-f2fs-devel@lists.sourceforge.net X-Mailman-Version: 2.1.21 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: linux-xfs@vger.kernel.org, linux-kernel@vger.kernel.org, linux-f2fs-devel@lists.sourceforge.net, cluster-devel@redhat.com, linux-mm@kvack.org, ocfs2-devel@oss.oracle.com, linux-fsdevel@vger.kernel.org, linux-ext4@vger.kernel.org, linux-erofs@lists.ozlabs.org, linux-btrfs@vger.kernel.org Content-Transfer-Encoding: 7bit Content-Type: text/plain; charset="us-ascii"; Format="flowed" Errors-To: linux-f2fs-devel-bounces@lists.sourceforge.net On 2/21/20 7:35 AM, Matthew Wilcox wrote: > On Thu, Feb 20, 2020 at 07:50:39PM -0800, John Hubbard wrote: >> This tiny patch made me pause, because I wasn't sure at first of the exact >> intent of the lines above. Once I worked it out, it seemed like it might >> be helpful (or overkill??) to add a few hints for the reader, especially since >> there are no hints in the function's (minimal) documentation header. What >> do you think of this? >> >> /* >> * If we can't read *any* pages without going past the inodes's isize >> * limit, give up entirely: >> */ >> if (index > end_index) >> return; >> >> /* Cap nr_to_read, in order to avoid overflowing the ULONG type: */ >> if (index + nr_to_read < index) >> nr_to_read = ULONG_MAX - index + 1; >> >> /* Cap nr_to_read, to avoid reading past the inode's isize limit: */ >> if (index + nr_to_read >= end_index) >> nr_to_read = end_index - index + 1; > > A little verbose for my taste ... How about this? Mine too, actually. :) I think your version below looks good. thanks, -- John Hubbard NVIDIA > > end_index = (isize - 1) >> PAGE_SHIFT; > if (index > end_index) > return; > /* Avoid wrapping to the beginning of the file */ > if (index + nr_to_read < index) > nr_to_read = ULONG_MAX - index + 1; > /* Don't read past the page containing the last byte of the file */ > if (index + nr_to_read >= end_index) > nr_to_read = end_index - index + 1; > _______________________________________________ Linux-f2fs-devel mailing list Linux-f2fs-devel@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/linux-f2fs-devel