[PATCH v4 01/28] libmultipath: Add initial framework

[John Garry]

>> new file mode 100644
>> index 0000000000000..e98b4b241020a
>> --- /dev/null
>> +++ b/include/linux/multipath.h
>> @@ -0,0 +1,28 @@
> 
> Please add an SPDX tag.

OK, will add

> And possibly a copyright.

I think that just the c file is fine.

> 
>> +
>> +#ifndef _LIBMULTIPATH_H
>> +#define _LIBMULTIPATH_H
>> +
>> +#include <linux/blkdev.h>
>> +#include <linux/srcu.h>
>> +
>> +struct mpath_device {
>> +    struct list_head    siblings;
>> +    struct gendisk        *disk;
>> +};
>> +
>> +struct mpath_head {
>> +    struct srcu_struct    srcu;
>> +    struct list_head    dev_list;    /* list of all mpath_devs */
>> +    struct mutex        lock;
>> +
>> +    refcount_t        refcount;
>> +
>> +    struct mpath_device __rcu         *current_path[MAX_NUMNODES];
>> +};
>> +
>> +int mpath_get_head(struct mpath_head *mpath_head);
>> +void mpath_put_head(struct mpath_head *mpath_head);
>> +int mpath_head_init(struct mpath_head *mpath_head);
>> +void mpath_head_uninit(struct mpath_head *mpath_head);
>> +
>> +#endif // _LIBMULTIPATH_H
>> diff --git a/lib/Kconfig b/lib/Kconfig
>> index 55748b68714e0..d0258bef374a1 100644
>> --- a/lib/Kconfig
>> +++ b/lib/Kconfig
>> @@ -636,3 +636,9 @@ config UNION_FIND
>>   config MIN_HEAP
>>       bool
>> +
>> +config LIBMULTIPATH
>> +    bool "MULTIPATH BLOCK DRIVER LIBRARY"
>> +    depends on BLOCK
>> +    help
>> +      If you say yes here then you get a multipath lib for block drivers
>> diff --git a/lib/Makefile b/lib/Makefile
>> index 7f75cc6edf94a..7ba5e13be4171 100644
>> --- a/lib/Makefile
>> +++ b/lib/Makefile
>> @@ -334,3 +334,5 @@ CONTEXT_ANALYSIS_test_context-analysis.o := y
>>   obj-$(CONFIG_CONTEXT_ANALYSIS_TEST) += test_context-analysis.o
>>   subdir-$(CONFIG_FORTIFY_SOURCE) += test_fortify
>> +
>> +obj-$(CONFIG_LIBMULTIPATH)    += multipath.o
>> diff --git a/lib/multipath.c b/lib/multipath.c
>> new file mode 100644
>> index 0000000000000..9cc398d266adf
>> --- /dev/null
>> +++ b/lib/multipath.c
>> @@ -0,0 +1,66 @@
>> +// SPDX-License-Identifier: GPL-2.0-only
>> +/*
>> + * Copyright (c) 2017-2018 Christoph Hellwig.
> A bit unusual, creating a new file and add a copyright
> from _another_ person ...
> 

This code is really just a refactoring of the NVMe multipath code. Since 
Christoph copyrighted that, I think it only proper to add his copyright 
here.

I'll remove it if Christoph wants.

> 
> Otherwise:
> Reviewed-by: Hannes Reinecke <hare at kernel.org>
> 

Thanks