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Message-ID: <482CEE1F.9050105@sgi.com>
Date: Fri, 16 May 2008 12:14:55 +1000
From: Lachlan McIlroy <lachlan@sgi.com>
Reply-To: lachlan@sgi.com
MIME-Version: 1.0
Subject: Re: [PATCH] xfs_dm_rdwr() needs to pass a vfsmount to dentry_open()
References: <482CE39F.9050404@sgi.com> <20080516015828.GC155679365@sgi.com>
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To: David Chinner <dgc@sgi.com>
Cc: xfs-dev <xfs-dev@sgi.com>, xfs-oss <xfs@oss.sgi.com>

David Chinner wrote:
> On Fri, May 16, 2008 at 11:30:07AM +1000, Lachlan McIlroy wrote:
>> There's a new check added to dentry_open():
>>
>>    if (!mnt) {
>>        printk(KERN_WARNING "%s called with NULL vfsmount\n", __func__);
>>        dump_stack();
>>        return ERR_PTR(-EINVAL);
>>    }
>>
>> We need to pass a mountpoint in the call to dentry_open() in xfs_dm_rdwr()
>> to avoid this code.
>>
>> --- fs/xfs/dmapi/xfs_dm.c_1.72	2008-05-15 13:23:41.000000000 +1000
>> +++ fs/xfs/dmapi/xfs_dm.c	2008-05-15 17:51:41.000000000 +1000
>> @@ -52,6 +52,8 @@
>> #include <dmapi_kern.h>
>> #include "xfs_dm.h"
>>
>> +#include <linux/mount.h>
> 
> Should be defined in fs/xfs/linux-2.6/xfs_linux.h, right?
It's not currently in xfs_linux.h.  It's needed for mntget().  I saw that
xfs_ioctl.c uses mntget() and pulls in linux/mount.h directly so I followed
suit.  I can add it to xfs_linux.h if you prefer.

> 
>> +
>> #define MAXNAMLEN MAXNAMELEN
>>
>> #define MIN_DIO_SIZE(mp)		((mp)->m_sb.sb_sectsize)
>> @@ -1121,7 +1123,7 @@ xfs_dm_rdwr(
>> 		return ENOMEM;
>> 	}
>>
>> -	file = dentry_open(dentry, NULL, oflags);
>> +	file = dentry_open(dentry, mntget(ip->i_mount->m_vfsmount), oflags);
>> 	if (IS_ERR(file)) {
>> 		return -PTR_ERR(file);
>> 	}
>> --- fs/xfs/linux-2.6/xfs_super.c_1.416	2008-05-15 13:23:43.000000000 +1000
>> +++ fs/xfs/linux-2.6/xfs_super.c	2008-05-15 13:29:49.000000000 +1000
>> @@ -1397,8 +1397,14 @@ xfs_fs_get_sb(
>> 	void			*data,
>> 	struct vfsmount		*mnt)
>> {
>> -	return get_sb_bdev(fs_type, flags, dev_name, data, xfs_fs_fill_super,
>> +	int	error;
>> +
>> +	error = get_sb_bdev(fs_type, flags, dev_name, data, 
>> xfs_fs_fill_super,
>> 			   mnt);
>> +	if (!error)
>> +		((struct xfs_mount *)mnt->mnt_sb->s_fs_info)->m_vfsmount = 
>> mnt;
> 
> As I previously suggested, please use XFS_M(mnt->mnt_sb) for this.

Sorry, missed that one.