From patchwork Wed Mar 27 23:46:20 2019 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: David Howells X-Patchwork-Id: 10874297 Return-Path: Received: from mail.wl.linuxfoundation.org (pdx-wl-mail.web.codeaurora.org [172.30.200.125]) by pdx-korg-patchwork-2.web.codeaurora.org (Postfix) with ESMTP id 420CA15AC for ; Wed, 27 Mar 2019 23:46:29 +0000 (UTC) Received: from mail.wl.linuxfoundation.org (localhost [127.0.0.1]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id 2908D28894 for ; Wed, 27 Mar 2019 23:46:29 +0000 (UTC) Received: by mail.wl.linuxfoundation.org (Postfix, from userid 486) id 1D15028A7D; Wed, 27 Mar 2019 23:46:29 +0000 (UTC) X-Spam-Checker-Version: SpamAssassin 3.3.1 (2010-03-16) on pdx-wl-mail.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-7.9 required=2.0 tests=BAYES_00,MAILING_LIST_MULTI, RCVD_IN_DNSWL_HI autolearn=ham version=3.3.1 Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id B7F0B28894 for ; Wed, 27 Mar 2019 23:46:24 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2387421AbfC0XqX (ORCPT ); Wed, 27 Mar 2019 19:46:23 -0400 Received: from mx1.redhat.com ([209.132.183.28]:43564 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1728360AbfC0XqX (ORCPT ); Wed, 27 Mar 2019 19:46:23 -0400 Received: from smtp.corp.redhat.com (int-mx04.intmail.prod.int.phx2.redhat.com [10.5.11.14]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mx1.redhat.com (Postfix) with ESMTPS id 9861E307EA83; Wed, 27 Mar 2019 23:46:22 +0000 (UTC) Received: from warthog.procyon.org.uk (ovpn-121-98.rdu2.redhat.com [10.10.121.98]) by smtp.corp.redhat.com (Postfix) with ESMTP id B3EC35D9C5; Wed, 27 Mar 2019 23:46:20 +0000 (UTC) Organization: Red Hat UK Ltd. 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Registered in England and Wales under Company Registration No. 3798903 Subject: [RFC PATCH 46/68] mtd: Provide fs_context-aware mount_mtd() replacement From: David Howells To: viro@zeniv.linux.org.uk Cc: David Woodhouse , Brian Norris , Boris Brezillon , Marek Vasut , Richard Weinberger , linux-mtd@lists.infradead.org, linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org, dhowells@redhat.com Date: Wed, 27 Mar 2019 23:46:20 +0000 Message-ID: <155373037997.7602.10121636631236011522.stgit@warthog.procyon.org.uk> In-Reply-To: <155372999953.7602.13784796495137723805.stgit@warthog.procyon.org.uk> References: <155372999953.7602.13784796495137723805.stgit@warthog.procyon.org.uk> User-Agent: StGit/unknown-version MIME-Version: 1.0 X-Scanned-By: MIMEDefang 2.79 on 10.5.11.14 X-Greylist: Sender IP whitelisted, not delayed by milter-greylist-4.5.16 (mx1.redhat.com [10.5.110.44]); Wed, 27 Mar 2019 23:46:22 +0000 (UTC) Sender: linux-fsdevel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-fsdevel@vger.kernel.org X-Virus-Scanned: ClamAV using ClamSMTP Provide a function, vfs_get_mtd_super(), to replace mount_mtd(), using an fs_context struct to hold the parameters. The mtd device pointer is cached in the struct, along with a destructor pointer as the mtd core may be in a module and, as such, unreachable by the core code that would release the fs_context. Signed-off-by: David Howells cc: David Woodhouse cc: Brian Norris cc: Boris Brezillon cc: Marek Vasut cc: Richard Weinberger cc: linux-mtd@lists.infradead.org --- drivers/mtd/mtdcore.h | 1 drivers/mtd/mtdsuper.c | 192 ++++++++++++++++++++++++++++++++++++++++++++ include/linux/fs_context.h | 3 - include/linux/mtd/super.h | 3 + 4 files changed, 196 insertions(+), 3 deletions(-) diff --git a/drivers/mtd/mtdcore.h b/drivers/mtd/mtdcore.h index b31c868019ad..b5eefeabf310 100644 --- a/drivers/mtd/mtdcore.h +++ b/drivers/mtd/mtdcore.h @@ -5,6 +5,7 @@ */ extern struct mutex mtd_table_mutex; +extern struct backing_dev_info *mtd_bdi; struct mtd_info *__mtd_next_device(int i); int __must_check add_mtd_device(struct mtd_info *mtd); diff --git a/drivers/mtd/mtdsuper.c b/drivers/mtd/mtdsuper.c index d58a61c09304..cf165f7c8632 100644 --- a/drivers/mtd/mtdsuper.c +++ b/drivers/mtd/mtdsuper.c @@ -19,6 +19,196 @@ #include #include #include +#include +#include "mtdcore.h" + +static void mtd_fc_destructor(struct fs_context *fc) +{ + if (fc->mtd) + put_mtd_device(fc->mtd); +} + +/* + * compare superblocks to see if they're equivalent + * - they are if the underlying MTD device is the same + */ +static int mtd_test_super(struct super_block *sb, struct fs_context *fc) +{ + struct mtd_info *mtd = fc->mtd; + + if (sb->s_mtd == mtd) { + pr_debug("MTDSB: Match on device %d (\"%s\")\n", + mtd->index, mtd->name); + return 1; + } + + pr_debug("MTDSB: No match, device %d (\"%s\"), device %d (\"%s\")\n", + sb->s_mtd->index, sb->s_mtd->name, mtd->index, mtd->name); + return 0; +} + +/* + * mark the superblock by the MTD device it is using + * - set the device number to be the correct MTD block device for pesuperstence + * of NFS exports + */ +static int mtd_set_super(struct super_block *sb, struct fs_context *fc) +{ + struct mtd_info *mtd = fc->mtd; + + sb->s_mtd = mtd; + sb->s_dev = MKDEV(MTD_BLOCK_MAJOR, mtd->index); + sb->s_bdi = bdi_get(mtd_bdi); + fc->mtd = NULL; + return 0; +} + +/* + * get a superblock on an MTD-backed filesystem + */ +static int mtd_get_sb(struct fs_context *fc, + int (*fill_super)(struct super_block *, + struct fs_context *)) +{ + struct super_block *sb; + struct mtd_info *mtd = fc->mtd; + int ret; + + sb = sget_fc(fc, mtd_test_super, mtd_set_super); + if (IS_ERR(sb)) + return PTR_ERR(sb); + + if (sb->s_root) { + /* new mountpoint for an already mounted superblock */ + pr_debug("MTDSB: Device %d (\"%s\") is already mounted\n", + mtd->index, mtd->name); + put_mtd_device(mtd); + } else { + /* fresh new superblock */ + pr_debug("MTDSB: New superblock for device %d (\"%s\")\n", + mtd->index, mtd->name); + + ret = fill_super(sb, fc); + if (ret < 0) + goto error_sb; + + sb->s_flags |= SB_ACTIVE; + } + + BUG_ON(fc->root); + fc->root = dget(sb->s_root); + return 0; + +error_sb: + deactivate_locked_super(sb); + return ret; +} + +/* + * get a superblock on an MTD-backed filesystem by MTD device number + */ +static int mtd_get_sb_by_nr(struct fs_context *fc, int mtdnr, + int (*fill_super)(struct super_block *, + struct fs_context *)) +{ + struct mtd_info *mtd; + + mtd = get_mtd_device(NULL, mtdnr); + if (IS_ERR(mtd)) { + errorf(fc, "MTDSB: Device #%u doesn't appear to exist\n", mtdnr); + return PTR_ERR(mtd); + } + + fc->mtd = mtd; + fc->dev_destructor = mtd_fc_destructor; + return mtd_get_sb(fc, fill_super); +} + +/** + * vfs_get_mtd_super - Get a superblock based on a single MTD device + * @fc: The filesystem context holding the parameters + * @fill_super: Helper to initialise a new superblock + */ +int vfs_get_mtd_super(struct fs_context *fc, + int (*fill_super)(struct super_block *sb, + struct fs_context *fc)) +{ +#ifdef CONFIG_BLOCK + struct block_device *bdev; + int ret, major; +#endif + int mtdnr; + + if (!fc->source) + return invalf(fc, "No source specified"); + + pr_debug("MTDSB: dev_name \"%s\"\n", fc->source); + + /* the preferred way of mounting in future; especially when + * CONFIG_BLOCK=n - we specify the underlying MTD device by number or + * by name, so that we don't require block device support to be present + * in the kernel. + */ + if (fc->source[0] == 'm' && + fc->source[1] == 't' && + fc->source[2] == 'd') { + if (fc->source[3] == ':') { + struct mtd_info *mtd; + + /* mount by MTD device name */ + pr_debug("MTDSB: mtd:%%s, name \"%s\"\n", + fc->source + 4); + + mtd = get_mtd_device_nm(fc->source + 4); + if (!IS_ERR(mtd)) { + fc->mtd = mtd; + fc->dev_destructor = mtd_fc_destructor; + return mtd_get_sb(fc, fill_super); + } + + errorf(fc, "MTD: MTD device with name \"%s\" not found", + fc->source + 4); + + } else if (isdigit(fc->source[3])) { + /* mount by MTD device number name */ + char *endptr; + + mtdnr = simple_strtoul(fc->source + 3, &endptr, 0); + if (!*endptr) { + /* It was a valid number */ + pr_debug("MTDSB: mtd%%d, mtdnr %d\n", mtdnr); + return mtd_get_sb_by_nr(fc, mtdnr, fill_super); + } + } + } + +#ifdef CONFIG_BLOCK + /* try the old way - the hack where we allowed users to mount + * /dev/mtdblock$(n) but didn't actually _use_ the blockdev + */ + bdev = lookup_bdev(fc->source); + if (IS_ERR(bdev)) { + ret = PTR_ERR(bdev); + errorf(fc, "MTD: Couldn't look up '%s': %d", fc->source, ret); + return ret; + } + pr_debug("MTDSB: lookup_bdev() returned 0\n"); + + major = MAJOR(bdev->bd_dev); + mtdnr = MINOR(bdev->bd_dev); + bdput(bdev); + + if (major == MTD_BLOCK_MAJOR) + return mtd_get_sb_by_nr(fc, mtdnr, fill_super); + +#endif /* CONFIG_BLOCK */ + + if (!(fc->sb_flags & SB_SILENT)) + errorf(fc, "MTD: Attempt to mount non-MTD device \"%s\"", + fc->source); + return -EINVAL; +} +EXPORT_SYMBOL_GPL(vfs_get_mtd_super); /* * compare superblocks to see if they're equivalent @@ -39,8 +229,6 @@ static int get_sb_mtd_compare(struct super_block *sb, void *_mtd) return 0; } -extern struct backing_dev_info *mtd_bdi; - /* * mark the superblock by the MTD device it is using * - set the device number to be the correct MTD block device for pesuperstence diff --git a/include/linux/fs_context.h b/include/linux/fs_context.h index 70fdebf1dc85..7c7eefb35cc3 100644 --- a/include/linux/fs_context.h +++ b/include/linux/fs_context.h @@ -77,7 +77,8 @@ struct fs_context { struct file_system_type *fs_type; void *fs_private; /* The filesystem's context */ union { - struct block_device *bdev; /* The backing blockdev (if applicable) */ + struct block_device *bdev; /* The backing blockdev (if applicable) */ + struct mtd_info *mtd; /* The backing mtd (if applicable) */ }; struct dentry *root; /* The root and superblock */ struct user_namespace *user_ns; /* The user namespace for this mount */ diff --git a/include/linux/mtd/super.h b/include/linux/mtd/super.h index f456230f9330..7ebd69e5c640 100644 --- a/include/linux/mtd/super.h +++ b/include/linux/mtd/super.h @@ -18,6 +18,9 @@ #include #include +extern int vfs_get_mtd_super(struct fs_context *fc, + int (*fill_super)(struct super_block *sb, + struct fs_context *fc)); extern struct dentry *mount_mtd(struct file_system_type *fs_type, int flags, const char *dev_name, void *data, int (*fill_super)(struct super_block *, void *, int));