From patchwork Sat Feb 13 02:01:29 2016 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Anand Jain X-Patchwork-Id: 8299281 Return-Path: X-Original-To: patchwork-linux-btrfs@patchwork.kernel.org Delivered-To: patchwork-parsemail@patchwork1.web.kernel.org Received: from mail.kernel.org (mail.kernel.org [198.145.29.136]) by patchwork1.web.kernel.org (Postfix) with ESMTP id 57AB09F372 for ; Sat, 13 Feb 2016 02:06:36 +0000 (UTC) Received: from mail.kernel.org (localhost [127.0.0.1]) by mail.kernel.org (Postfix) with ESMTP id 52B4F204AF for ; Sat, 13 Feb 2016 02:06:35 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 1DA53204AB for ; Sat, 13 Feb 2016 02:06:34 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751177AbcBMCCC (ORCPT ); Fri, 12 Feb 2016 21:02:02 -0500 Received: from aserp1040.oracle.com ([141.146.126.69]:41928 "EHLO aserp1040.oracle.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751137AbcBMCCA (ORCPT ); Fri, 12 Feb 2016 21:02:00 -0500 Received: from aserv0021.oracle.com (aserv0021.oracle.com [141.146.126.233]) by aserp1040.oracle.com (Sentrion-MTA-4.3.2/Sentrion-MTA-4.3.2) with ESMTP id u1D21vL2026289 (version=TLSv1 cipher=DHE-RSA-AES256-SHA bits=256 verify=OK); Sat, 13 Feb 2016 02:01:57 GMT Received: from userv0121.oracle.com (userv0121.oracle.com [156.151.31.72]) by aserv0021.oracle.com (8.13.8/8.13.8) with ESMTP id u1D21vsK031027 (version=TLSv1/SSLv3 cipher=DHE-RSA-AES256-SHA bits=256 verify=FAIL); Sat, 13 Feb 2016 02:01:57 GMT Received: from abhmp0017.oracle.com (abhmp0017.oracle.com [141.146.116.23]) by userv0121.oracle.com (8.13.8/8.13.8) with ESMTP id u1D21u1W021687; Sat, 13 Feb 2016 02:01:56 GMT Received: from localhost.localdomain (/42.60.24.64) by default (Oracle Beehive Gateway v4.0) with ESMTP ; Fri, 12 Feb 2016 18:01:56 -0800 From: Anand Jain To: dsterba@suse.cz Cc: linux-btrfs@vger.kernel.org Subject: [PATCH 02/13] btrfs: create a helper function to read the disk super Date: Sat, 13 Feb 2016 10:01:29 +0800 Message-Id: <1455328900-1476-3-git-send-email-anand.jain@oracle.com> X-Mailer: git-send-email 2.7.0 In-Reply-To: <1455328900-1476-1-git-send-email-anand.jain@oracle.com> References: <1455328900-1476-1-git-send-email-anand.jain@oracle.com> X-Source-IP: aserv0021.oracle.com [141.146.126.233] Sender: linux-btrfs-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-btrfs@vger.kernel.org X-Spam-Status: No, score=-7.0 required=5.0 tests=BAYES_00, RCVD_IN_DNSWL_HI, RP_MATCHES_RCVD, UNPARSEABLE_RELAY autolearn=unavailable version=3.3.1 X-Spam-Checker-Version: SpamAssassin 3.3.1 (2010-03-16) on mail.kernel.org X-Virus-Scanned: ClamAV using ClamSMTP A part of code from btrfs_scan_one_device() is moved to a new function btrfs_read_disk_super(), so that former function looks cleaner. (In this process it also moves the code which ensures null terminating label). So this creates easy opportunity to merge various duplicate codes on read disk super. Earlier attempt to merge duplicate codes highlighted that there were some issues for which there are duplicate codes (to read disk super), however it was not clear what was the issue. So until we figure that out, its better to keep them in a separate functions. Signed-off-by: Anand Jain --- fs/btrfs/volumes.c | 87 ++++++++++++++++++++++++++++++++---------------------- 1 file changed, 52 insertions(+), 35 deletions(-) diff --git a/fs/btrfs/volumes.c b/fs/btrfs/volumes.c index 6e0e439..9860b10 100644 --- a/fs/btrfs/volumes.c +++ b/fs/btrfs/volumes.c @@ -988,6 +988,56 @@ int btrfs_open_devices(struct btrfs_fs_devices *fs_devices, return ret; } +void btrfs_release_disk_super(struct page *page) +{ + kunmap(page); + page_cache_release(page); +} + +int btrfs_read_disk_super(struct block_device *bdev, u64 bytenr, + struct page **page, struct btrfs_super_block **disk_super) +{ + void *p; + pgoff_t index; + + /* make sure our super fits in the device */ + if (bytenr + PAGE_CACHE_SIZE >= i_size_read(bdev->bd_inode)) + return 1; + + /* make sure our super fits in the page */ + if (sizeof(**disk_super) > PAGE_CACHE_SIZE) + return 1; + + /* make sure our super doesn't straddle pages on disk */ + index = bytenr >> PAGE_CACHE_SHIFT; + if ((bytenr + sizeof(**disk_super) - 1) >> PAGE_CACHE_SHIFT != index) + return 1; + + /* pull in the page with our super */ + *page = read_cache_page_gfp(bdev->bd_inode->i_mapping, + index, GFP_NOFS); + + if (IS_ERR_OR_NULL(*page)) + return 1; + + p = kmap(*page); + + /* align our pointer to the offset of the super block */ + *disk_super = p + (bytenr & ~PAGE_CACHE_MASK); + + if (btrfs_super_bytenr(*disk_super) != bytenr || + btrfs_super_magic(*disk_super) != BTRFS_MAGIC) { + btrfs_release_disk_super(*page); + return 1; + } + + if ((*disk_super)->label[0] && + (*disk_super)->label[BTRFS_LABEL_SIZE - 1]) + (*disk_super)->label[BTRFS_LABEL_SIZE - 1] = '\0'; + + return 0; +} + /* * Look for a btrfs signature on a device. This may be called out of the mount path * and we are not allowed to call set_blocksize during the scan. The superblock @@ -999,13 +1049,11 @@ int btrfs_scan_one_device(const char *path, fmode_t flags, void *holder, struct btrfs_super_block *disk_super; struct block_device *bdev; struct page *page; - void *p; int ret = -EINVAL; u64 devid; u64 transid; u64 total_devices; u64 bytenr; - pgoff_t index; /* * we would like to check all the supers, but that would make @@ -1018,41 +1066,14 @@ int btrfs_scan_one_device(const char *path, fmode_t flags, void *holder, mutex_lock(&uuid_mutex); bdev = blkdev_get_by_path(path, flags, holder); - if (IS_ERR(bdev)) { ret = PTR_ERR(bdev); goto error; } - /* make sure our super fits in the device */ - if (bytenr + PAGE_CACHE_SIZE >= i_size_read(bdev->bd_inode)) + if (btrfs_read_disk_super(bdev, bytenr, &page, &disk_super)) goto error_bdev_put; - /* make sure our super fits in the page */ - if (sizeof(*disk_super) > PAGE_CACHE_SIZE) - goto error_bdev_put; - - /* make sure our super doesn't straddle pages on disk */ - index = bytenr >> PAGE_CACHE_SHIFT; - if ((bytenr + sizeof(*disk_super) - 1) >> PAGE_CACHE_SHIFT != index) - goto error_bdev_put; - - /* pull in the page with our super */ - page = read_cache_page_gfp(bdev->bd_inode->i_mapping, - index, GFP_NOFS); - - if (IS_ERR_OR_NULL(page)) - goto error_bdev_put; - - p = kmap(page); - - /* align our pointer to the offset of the super block */ - disk_super = p + (bytenr & ~PAGE_CACHE_MASK); - - if (btrfs_super_bytenr(disk_super) != bytenr || - btrfs_super_magic(disk_super) != BTRFS_MAGIC) - goto error_unmap; - devid = btrfs_stack_device_id(&disk_super->dev_item); transid = btrfs_super_generation(disk_super); total_devices = btrfs_super_num_devices(disk_super); @@ -1060,8 +1081,6 @@ int btrfs_scan_one_device(const char *path, fmode_t flags, void *holder, ret = device_list_add(path, disk_super, devid, fs_devices_ret); if (ret > 0) { if (disk_super->label[0]) { - if (disk_super->label[BTRFS_LABEL_SIZE - 1]) - disk_super->label[BTRFS_LABEL_SIZE - 1] = '\0'; printk(KERN_INFO "BTRFS: device label %s ", disk_super->label); } else { printk(KERN_INFO "BTRFS: device fsid %pU ", disk_super->fsid); @@ -1073,9 +1092,7 @@ int btrfs_scan_one_device(const char *path, fmode_t flags, void *holder, if (!ret && fs_devices_ret) (*fs_devices_ret)->total_devices = total_devices; -error_unmap: - kunmap(page); - page_cache_release(page); + btrfs_release_disk_super(page); error_bdev_put: blkdev_put(bdev, flags);