From patchwork Mon Feb 15 17:33:59 2016 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: David Sterba X-Patchwork-Id: 8317351 Return-Path: X-Original-To: patchwork-linux-btrfs@patchwork.kernel.org Delivered-To: patchwork-parsemail@patchwork2.web.kernel.org Received: from mail.kernel.org (mail.kernel.org [198.145.29.136]) by patchwork2.web.kernel.org (Postfix) with ESMTP id 2DCC6C02AA for ; Mon, 15 Feb 2016 17:34:53 +0000 (UTC) Received: from mail.kernel.org (localhost [127.0.0.1]) by mail.kernel.org (Postfix) with ESMTP id 168E72039C for ; Mon, 15 Feb 2016 17:34:52 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 015CF202E5 for ; Mon, 15 Feb 2016 17:34:51 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753734AbcBOReF (ORCPT ); Mon, 15 Feb 2016 12:34:05 -0500 Received: from mx2.suse.de ([195.135.220.15]:34891 "EHLO mx2.suse.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753019AbcBOReE (ORCPT ); Mon, 15 Feb 2016 12:34:04 -0500 X-Virus-Scanned: by amavisd-new at test-mx.suse.de Received: from relay1.suse.de (charybdis-ext.suse.de [195.135.220.254]) by mx2.suse.de (Postfix) with ESMTP id 03AA2ACCC; Mon, 15 Feb 2016 17:34:03 +0000 (UTC) Received: by ds.suse.cz (Postfix, from userid 10065) id 07D32DA9DC; Mon, 15 Feb 2016 18:33:59 +0100 (CET) From: David Sterba To: linux-btrfs@vger.kernel.org Cc: Anand Jain , David Sterba Subject: [PATCH 01/15] btrfs: create a helper function to read the disk super Date: Mon, 15 Feb 2016 18:33:59 +0100 Message-Id: <7870f31d036002d5880b65ff8cc745a01619af1b.1455556900.git.dsterba@suse.com> X-Mailer: git-send-email 2.7.1 In-Reply-To: References: Sender: linux-btrfs-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-btrfs@vger.kernel.org X-Spam-Status: No, score=-6.9 required=5.0 tests=BAYES_00, RCVD_IN_DNSWL_HI, RP_MATCHES_RCVD, UNPARSEABLE_RELAY autolearn=ham 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 From: Anand Jain 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 [ use GFP_KERNEL ] Signed-off-by: David Sterba --- 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 366b335946fa..fa119ea8c74b 100644 --- a/fs/btrfs/volumes.c +++ b/fs/btrfs/volumes.c @@ -987,6 +987,56 @@ 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_KERNEL); + + 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 @@ -998,13 +1048,11 @@ 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 @@ -1017,41 +1065,14 @@ 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)) - 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)) + if (btrfs_read_disk_super(bdev, bytenr, &page, &disk_super)) 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); @@ -1059,8 +1080,6 @@ 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); @@ -1072,9 +1091,7 @@ 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);