Re: [RFC PATCH 0/6] Convert mount_single-using filesystems to fs_context

From: Richard Weinberger <richard@nod.at>
To: David Howells <dhowells@redhat.com>
Cc: viro@zeniv.linux.org.uk, linux-block@vger.kernel.org,
	squashfs-devel@lists.sourceforge.net,
	Marek Vasut <marek.vasut@gmail.com>,
	Brian Norris <computersforpeace@gmail.com>,
	Nicolas Pitre <nico@linaro.org>,
	Boris Brezillon <bbrezillon@kernel.org>,
	linux-mtd@lists.infradead.org,
	David Woodhouse <dwmw2@infradead.org>,
	Phillip Lougher <phillip@squashfs.org.uk>,
	linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org
Subject: Re: [RFC PATCH 0/6] Convert mount_single-using filesystems to fs_context
Date: Thu, 21 Mar 2019 13:48:39 +0100	[thread overview]
Message-ID: <3463221.D14WHduXq3@blindfold> (raw)
In-Reply-To: <155316902426.29884.2476392753144421312.stgit@warthog.procyon.org.uk>

Am Donnerstag, 21. März 2019, 12:50:24 CET schrieb David Howells:
> 
> Hi Al,
> 
> Here's a set of patches that convert romfs, cramfs, jffs2 and squashfs to
> use the new fs_context struct and replace mount_mtd().  They have
> prerequisite commits (such as replacing mount_bdev()) that can be found in
> the branch detailed below.
> 
>  (1) Provide a replacement for mount_mtd() that takes an fs_context to
>      specify the parameters.
> 
>      I also put an mtd device pointer into the fs_context struct for use in
>      the sget_fc() test and set functions plus a destructor because
>      put_fs_context() can't reach into the mtd module.
> 
>  (2) Convert romfs.
> 
>  (3) Convert cramfs.
> 
>  (4) Convert jffs2.
> 
>  (5) Get rid of the now-obsolete mount_mtd() function.
> 
>  (6) Convert squashfs.
> 
> These can be found in the following branch:
> 
> 	http://git.kernel.org/cgit/linux/kernel/git/dhowells/linux-fs.git/log/?h=mount-api-viro

Hmm, I pulled this into 5.1-rc1 to test jffs2 but it oopes already while booting:

[    5.999847] BUG: unable to handle kernel NULL pointer dereference at 0000000000000068
[    6.002273] #PF error: [normal kernel read fault]
[    6.002912] PGD 0 P4D 0 
[    6.003241] Oops: 0000 [#1] SMP PTI
[    6.003690] CPU: 3 PID: 1221 Comm: mount Not tainted 5.1.0-rc1+ #372
[    6.004494] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS rel-1.11.0-0-g63451fc-prebuilt.qemu-project.org 04/01/2014
[    6.004504] RIP: 0010:reconfigure_super+0x17/0x1e0
[    6.004505] Code: 00 01 75 83 48 89 df e8 c7 e5 ff ff e9 76 ff ff ff 66 90 41 56 41 55 41 54 55 53 f7 47 68 ae ff 7f fd 48 8b 47 28 44 8b 77 64 <48> 8b 68 68 0f 85 a2 01 00 00 8b 95 38 02 00 00 85 d2 0f 85 89 01
[    6.004506] RSP: 0018:ffffb43cc0dafdf0 EFLAGS: 00010246
[    6.004507] RAX: 0000000000000000 RBX: ffff9d21b925cb00 RCX: ffff9d21b973009c
[    6.004508] RDX: 0000000000000001 RSI: ffff9d21b925cb00 RDI: ffff9d21b925cb00
[    6.004508] RBP: ffff9d21b9730000 R08: 0000000000200000 R09: 0000000000000000
[    6.004509] R10: ffffb43cc0dafe78 R11: 61c8864680b583eb R12: ffff9d21ba0cd000
[    6.004509] R13: ffffffff8d95a460 R14: 0000000000000000 R15: 0000000000000020
[    6.004512] FS:  00007fad96cea480(0000) GS:ffff9d21bab80000(0000) knlGS:0000000000000000
[    6.004514] CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
[    6.004515] CR2: 0000000000000068 CR3: 0000000178dec000 CR4: 00000000000006e0
[    6.004516] Call Trace:
[    6.004530]  ? debugfs_get_inode+0x50/0x50
[    6.022494]  vfs_get_super+0x9c/0xe0
[    6.022973]  vfs_get_tree+0x38/0xf0
[    6.023451]  do_mount+0x728/0xd20
[    6.023905]  ? _copy_from_user+0x37/0x60
[    6.024436]  ? memdup_user+0x39/0x60
[    6.024917]  ksys_mount+0x7b/0xd0
[    6.025368]  __x64_sys_mount+0x1c/0x20
[    6.025876]  do_syscall_64+0x43/0xf0
[    6.026375]  entry_SYSCALL_64_after_hwframe+0x44/0xa9

Do I miss some other fix?

Thanks,
//richard