Re: [PATCH 5/7] NFS: Create a common xdev_mount() function

["Myklebust, Trond" <Trond.Myklebust@xxxxxxxxxx>]

On Mon, 2012-04-30 at 14:40 -0400, bjschuma@xxxxxxxxxx wrote:
> From: Bryan Schumaker <bjschuma@xxxxxxxxxx>
> 
> The only difference between nfs_xdev_mount() and nfs4_xdev_mount() is the
> unshared flag, so I pass this as an nfs_mount_info parameter so we can
> share more code.
> 
> Signed-off-by: Bryan Schumaker <bjschuma@xxxxxxxxxx>
> ---
>  fs/nfs/super.c |  126 ++++++++++++++++----------------------------------------
>  1 file changed, 35 insertions(+), 91 deletions(-)
> 
> diff --git a/fs/nfs/super.c b/fs/nfs/super.c
> index b9ee798..eefb3ed 100644
> --- a/fs/nfs/super.c
> +++ b/fs/nfs/super.c
> @@ -2126,6 +2126,7 @@ static inline void nfs_initialise_sb(struct super_block *sb)
>  struct nfs_mount_info {
>  	void (*fill_super)(struct super_block *, struct nfs_mount_info *);
>  	struct nfs_parsed_mount_data *parsed;
> +	struct nfs_clone_mount *cloned;
>  	unsigned int unshared;
>  };
>  
> @@ -2159,8 +2160,9 @@ static void nfs_fill_super(struct super_block *sb,
>   * Finish setting up a cloned NFS2/3 superblock
>   */
>  static void nfs_clone_super(struct super_block *sb,
> -			    const struct super_block *old_sb)
> +			    struct nfs_mount_info *mount_info)
>  {
> +	const struct super_block *old_sb = mount_info->cloned->sb;
>  	struct nfs_server *server = NFS_SB(sb);
>  
>  	sb->s_blocksize_bits = old_sb->s_blocksize_bits;
> @@ -2439,13 +2441,13 @@ static void nfs_kill_super(struct super_block *s)
>  }
>  
>  /*
> - * Clone an NFS2/3 server record on xdev traversal (FSID-change)
> + * Clone an NFS2/3/4 server record on xdev traversal (FSID-change)
>   */
>  static struct dentry *
> -nfs_xdev_mount(struct file_system_type *fs_type, int flags,
> -		const char *dev_name, void *raw_data)
> +nfs_xdev_mount_common(struct file_system_type *fs_type, int flags,
> +		const char *dev_name, struct nfs_mount_info *mount_info)
>  {
> -	struct nfs_clone_mount *data = raw_data;
> +	struct nfs_clone_mount *data = mount_info->cloned;
>  	struct super_block *s;
>  	struct nfs_server *server;
>  	struct dentry *mntroot;
> @@ -2455,7 +2457,7 @@ nfs_xdev_mount(struct file_system_type *fs_type, int flags,
>  	};
>  	int error;
>  
> -	dprintk("--> nfs_xdev_mount()\n");
> +	dprintk("--> nfs_xdev_mount_common()\n");
>  
>  	/* create a new volume representation */
>  	server = nfs_clone_server(NFS_SB(data->sb), data->fh, data->fattr, data->authflavor);
> @@ -2465,7 +2467,7 @@ nfs_xdev_mount(struct file_system_type *fs_type, int flags,
>  	}
>  	sb_mntdata.server = server;
>  
> -	if (server->flags & NFS_MOUNT_UNSHARED)
> +	if (server->flags & mount_info->unshared)
>  		compare_super = NULL;
>  
>  	/* -o noac implies -o sync */
> @@ -2490,7 +2492,7 @@ nfs_xdev_mount(struct file_system_type *fs_type, int flags,
>  
>  	if (!s->s_root) {
>  		/* initial superblock/root creation */
> -		nfs_clone_super(s, data->sb);
> +		mount_info->fill_super(s, mount_info);
>  		nfs_fscache_get_super_cookie(s, NULL, data);
>  	}
>  
> @@ -2510,13 +2512,13 @@ nfs_xdev_mount(struct file_system_type *fs_type, int flags,
>  	/* clone any lsm security options from the parent to the new sb */
>  	security_sb_clone_mnt_opts(data->sb, s);
>  
> -	dprintk("<-- nfs_xdev_mount() = 0\n");
> +	dprintk("<-- nfs_xdev_mount_common() = 0\n");
>  	return mntroot;
>  
>  out_err_nosb:
>  	nfs_free_server(server);
>  out_err_noserver:
> -	dprintk("<-- nfs_xdev_mount() = %d [error]\n", error);
> +	dprintk("<-- nfs_xdev_mount_common() = %d [error]\n", error);
>  	return ERR_PTR(error);
>  
>  error_splat_super:
> @@ -2524,18 +2526,34 @@ error_splat_super:
>  		bdi_unregister(&server->backing_dev_info);
>  error_splat_bdi:
>  	deactivate_locked_super(s);
> -	dprintk("<-- nfs_xdev_mount() = %d [splat]\n", error);
> +	dprintk("<-- nfs_xdev_mount_common() = %d [splat]\n", error);
>  	return ERR_PTR(error);
>  }
>  
> +/*
> + * Clone an NFS2/3 server record on xdev traversal (FSID-change)
> + */
> +static struct dentry *
> +nfs_xdev_mount(struct file_system_type *fs_type, int flags,
> +		const char *dev_name, void *raw_data)
> +{
> +	struct nfs_mount_info mount_info = {
> +		.fill_super = nfs_clone_super,
> +		.cloned   = raw_data,
> +		.unshared = NFS_MOUNT_UNSHARED,

Why the change in share behaviour?

> +	};
> +	return nfs_xdev_mount_common(&nfs_fs_type, flags, dev_name, &mount_info);
> +}
> +
>  #ifdef CONFIG_NFS_V4
>  
>  /*
>   * Finish setting up a cloned NFS4 superblock
>   */
>  static void nfs4_clone_super(struct super_block *sb,
> -			    const struct super_block *old_sb)
> +			     struct nfs_mount_info *mount_info)
>  {
> +	const struct super_block *old_sb = mount_info->cloned->sb;
>  	sb->s_blocksize_bits = old_sb->s_blocksize_bits;
>  	sb->s_blocksize = old_sb->s_blocksize;
>  	sb->s_maxbytes = old_sb->s_maxbytes;
> @@ -2787,86 +2805,12 @@ static struct dentry *
>  nfs4_xdev_mount(struct file_system_type *fs_type, int flags,
>  		 const char *dev_name, void *raw_data)
>  {
> -	struct nfs_clone_mount *data = raw_data;
> -	struct super_block *s;
> -	struct nfs_server *server;
> -	struct dentry *mntroot;
> -	int (*compare_super)(struct super_block *, void *) = nfs_compare_super;
> -	struct nfs_sb_mountdata sb_mntdata = {
> -		.mntflags = flags,
> +	struct nfs_mount_info mount_info = {
> +		.fill_super = nfs4_clone_super,
> +		.cloned = raw_data,
> +		.unshared = NFS4_MOUNT_UNSHARED,
>  	};
> -	int error;
> -
> -	dprintk("--> nfs4_xdev_mount()\n");
> -
> -	/* create a new volume representation */
> -	server = nfs_clone_server(NFS_SB(data->sb), data->fh, data->fattr, data->authflavor);
> -	if (IS_ERR(server)) {
> -		error = PTR_ERR(server);
> -		goto out_err_noserver;
> -	}
> -	sb_mntdata.server = server;
> -
> -	if (server->flags & NFS4_MOUNT_UNSHARED)
> -		compare_super = NULL;
> -
> -	/* -o noac implies -o sync */
> -	if (server->flags & NFS_MOUNT_NOAC)
> -		sb_mntdata.mntflags |= MS_SYNCHRONOUS;
> -
> -	/* Get a superblock - note that we may end up sharing one that already exists */
> -	s = sget(&nfs4_fs_type, compare_super, nfs_set_super, &sb_mntdata);
> -	if (IS_ERR(s)) {
> -		error = PTR_ERR(s);
> -		goto out_err_nosb;
> -	}
> -
> -	if (s->s_fs_info != server) {
> -		nfs_free_server(server);
> -		server = NULL;
> -	} else {
> -		error = nfs_bdi_register(server);
> -		if (error)
> -			goto error_splat_bdi;
> -	}
> -
> -	if (!s->s_root) {
> -		/* initial superblock/root creation */
> -		nfs4_clone_super(s, data->sb);
> -		nfs_fscache_get_super_cookie(s, NULL, data);
> -	}
> -
> -	mntroot = nfs_get_root(s, data->fh, dev_name);
> -	if (IS_ERR(mntroot)) {
> -		error = PTR_ERR(mntroot);
> -		goto error_splat_super;
> -	}
> -	if (mntroot->d_inode->i_op != NFS_SB(s)->nfs_client->rpc_ops->dir_inode_ops) {
> -		dput(mntroot);
> -		error = -ESTALE;
> -		goto error_splat_super;
> -	}
> -
> -	s->s_flags |= MS_ACTIVE;
> -
> -	security_sb_clone_mnt_opts(data->sb, s);
> -
> -	dprintk("<-- nfs4_xdev_mount() = 0\n");
> -	return mntroot;
> -
> -out_err_nosb:
> -	nfs_free_server(server);
> -out_err_noserver:
> -	dprintk("<-- nfs4_xdev_mount() = %d [error]\n", error);
> -	return ERR_PTR(error);
> -
> -error_splat_super:
> -	if (server && !s->s_root)
> -		bdi_unregister(&server->backing_dev_info);
> -error_splat_bdi:
> -	deactivate_locked_super(s);
> -	dprintk("<-- nfs4_xdev_mount() = %d [splat]\n", error);
> -	return ERR_PTR(error);
> +	return nfs_xdev_mount_common(&nfs4_fs_type, flags, dev_name, &mount_info);
>  }
>  
>  static struct dentry *

-- 
Trond Myklebust
Linux NFS client maintainer

NetApp
Trond.Myklebust@xxxxxxxxxx
www.netapp.com

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