Re: [Qemu-devel] [PATCH v6 1/2] block/vxhs.c: Add support for a new block device type called "vxhs"

[Stefan Hajnoczi <stefanha@gmail.com>]

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On Mon, Nov 07, 2016 at 04:59:44PM -0800, Ashish Mittal wrote:
> Source code for the qnio library that this code loads can be downloaded from:
> https://github.com/MittalAshish/libqnio.git
> 
> Sample command line using the JSON syntax:
> ./qemu-system-x86_64 -name instance-00000008 -S -vnc 0.0.0.0:0 -k en-us
> -vga cirrus -device virtio-balloon-pci,id=balloon0,bus=pci.0,addr=0x5
> -msg timestamp=on
> 'json:{"driver":"vxhs","vdisk-id":"c3e9095a-a5ee-4dce-afeb-2a59fb387410",
> "server":{"host":"172.172.17.4","port":"9999"}}'
> 
> Sample command line using the URI syntax:
> qemu-img convert -f raw -O raw -n
> /var/lib/nova/instances/_base/0c5eacd5ebea5ed914b6a3e7b18f1ce734c386ad
> vxhs://192.168.0.1:9999/c6718f6b-0401-441d-a8c3-1f0064d75ee0
> 
> Signed-off-by: Ashish Mittal <ashish.mittal@veritas.com>
> ---
> v6 changelog:
> (1) Added qemu-iotests for VxHS as a new patch in the series.
> (2) Replaced release version from 2.8 to 2.9 in block-core.json.
> 
> v5 changelog:
> (1) Incorporated v4 review comments.
> 
> v4 changelog:
> (1) Incorporated v3 review comments on QAPI changes.
> (2) Added refcounting for device open/close.
>     Free library resources on last device close.
> 
> v3 changelog:
> (1) Added QAPI schema for the VxHS driver.
> 
> v2 changelog:
> (1) Changes done in response to v1 comments.
> 
>  block/Makefile.objs  |   2 +
>  block/trace-events   |  21 ++
>  block/vxhs.c         | 689 +++++++++++++++++++++++++++++++++++++++++++++++++++
>  configure            |  41 +++
>  qapi/block-core.json |  21 +-
>  5 files changed, 772 insertions(+), 2 deletions(-)
>  create mode 100644 block/vxhs.c
> 
> diff --git a/block/Makefile.objs b/block/Makefile.objs
> index 67a036a..58313a2 100644
> --- a/block/Makefile.objs
> +++ b/block/Makefile.objs
> @@ -18,6 +18,7 @@ block-obj-$(CONFIG_LIBNFS) += nfs.o
>  block-obj-$(CONFIG_CURL) += curl.o
>  block-obj-$(CONFIG_RBD) += rbd.o
>  block-obj-$(CONFIG_GLUSTERFS) += gluster.o
> +block-obj-$(CONFIG_VXHS) += vxhs.o
>  block-obj-$(CONFIG_ARCHIPELAGO) += archipelago.o
>  block-obj-$(CONFIG_LIBSSH2) += ssh.o
>  block-obj-y += accounting.o dirty-bitmap.o
> @@ -38,6 +39,7 @@ rbd.o-cflags       := $(RBD_CFLAGS)
>  rbd.o-libs         := $(RBD_LIBS)
>  gluster.o-cflags   := $(GLUSTERFS_CFLAGS)
>  gluster.o-libs     := $(GLUSTERFS_LIBS)
> +vxhs.o-libs        := $(VXHS_LIBS)
>  ssh.o-cflags       := $(LIBSSH2_CFLAGS)
>  ssh.o-libs         := $(LIBSSH2_LIBS)
>  archipelago.o-libs := $(ARCHIPELAGO_LIBS)
> diff --git a/block/trace-events b/block/trace-events
> index 882c903..efdd5ef 100644
> --- a/block/trace-events
> +++ b/block/trace-events
> @@ -112,3 +112,24 @@ qed_aio_write_data(void *s, void *acb, int ret, uint64_t offset, size_t len) "s
>  qed_aio_write_prefill(void *s, void *acb, uint64_t start, size_t len, uint64_t offset) "s %p acb %p start %"PRIu64" len %zu offset %"PRIu64
>  qed_aio_write_postfill(void *s, void *acb, uint64_t start, size_t len, uint64_t offset) "s %p acb %p start %"PRIu64" len %zu offset %"PRIu64
>  qed_aio_write_main(void *s, void *acb, int ret, uint64_t offset, size_t len) "s %p acb %p ret %d offset %"PRIu64" len %zu"
> +
> +# block/vxhs.c
> +vxhs_iio_callback(int error, int reason) "ctx is NULL: error %d, reason %d"
> +vxhs_setup_qnio(void *s) "Context to HyperScale IO manager = %p"
> +vxhs_iio_callback_chnfail(int err, int error) "QNIO channel failed, no i/o %d, %d"
> +vxhs_iio_callback_unknwn(int opcode, int err) "unexpected opcode %d, errno %d"
> +vxhs_open_fail(int ret) "Could not open the device. Error = %d"
> +vxhs_open_epipe(int ret) "Could not create a pipe for device. Bailing out. Error=%d"
> +vxhs_aio_rw_invalid(int req) "Invalid I/O request iodir %d"
> +vxhs_aio_rw_ioerr(char *guid, int iodir, uint64_t size, uint64_t off, void *acb, int ret, int err) "IO ERROR (vDisk %s) FOR : Read/Write = %d size = %lu offset = %lu ACB = %p. Error = %d, errno = %d"
> +vxhs_get_vdisk_stat_err(char *guid, int ret, int err) "vDisk (%s) stat ioctl failed, ret = %d, errno = %d"
> +vxhs_get_vdisk_stat(char *vdisk_guid, uint64_t vdisk_size) "vDisk %s stat ioctl returned size %lu"
> +vxhs_qnio_iio_open(const char *ip) "Failed to connect to storage agent on host-ip %s"
> +vxhs_qnio_iio_devopen(const char *fname) "Failed to open vdisk device: %s"
> +vxhs_complete_aio(void *acb, uint64_t ret) "aio failed acb %p ret %ld"
> +vxhs_parse_uri_filename(const char *filename) "URI passed via bdrv_parse_filename %s"
> +vxhs_qemu_init_vdisk(const char *vdisk_id) "vdisk-id from json %s"
> +vxhs_parse_uri_hostinfo(int num, char *host, int port) "Host %d: IP %s, Port %d"
> +vxhs_qemu_init(char *of_vsa_addr, int port) "Adding host %s:%d to BDRVVXHSState"
> +vxhs_qemu_init_filename(const char *filename) "Filename passed as %s"
> +vxhs_close(char *vdisk_guid) "Closing vdisk %s"
> diff --git a/block/vxhs.c b/block/vxhs.c
> new file mode 100644
> index 0000000..8913e8f
> --- /dev/null
> +++ b/block/vxhs.c
> @@ -0,0 +1,689 @@
> +/*
> + * QEMU Block driver for Veritas HyperScale (VxHS)
> + *
> + * This work is licensed under the terms of the GNU GPL, version 2 or later.
> + * See the COPYING file in the top-level directory.
> + *
> + */
> +
> +#include "qemu/osdep.h"
> +#include "block/block_int.h"
> +#include <qnio/qnio_api.h>

Please move system headers (<>) above user headers ("").  This way you
can be sure the system header isn't affected by any macros defined by
user headers.

> +#include "qapi/qmp/qerror.h"
> +#include "qapi/qmp/qdict.h"
> +#include "qapi/qmp/qstring.h"
> +#include "trace.h"
> +#include "qemu/uri.h"
> +#include "qapi/error.h"
> +#include "qemu/error-report.h"

Is this header file needed?

> +
> +#define VDISK_FD_READ               0
> +#define VDISK_FD_WRITE              1
> +
> +#define VXHS_OPT_FILENAME           "filename"
> +#define VXHS_OPT_VDISK_ID           "vdisk-id"
> +#define VXHS_OPT_SERVER             "server"
> +#define VXHS_OPT_HOST               "host"
> +#define VXHS_OPT_PORT               "port"
> +
> +typedef struct QNIOLibState {
> +    int refcnt;
> +    void *context;
> +} QNIOLibState;
> +
> +typedef enum {
> +    VDISK_AIO_READ,
> +    VDISK_AIO_WRITE,
> +    VDISK_STAT

This is unused.

> +} VDISKAIOCmd;

This typedef is unused but the VDISK_AIO_READ/VDISK_AIO_WRITE enum
constants are used.  Please use the typedef name instead of int.  That
way it's clear that the only valid values are the VDISK_* enum
constants.

> +
> +/*
> + * HyperScale AIO callbacks structure
> + */
> +typedef struct VXHSAIOCB {
> +    BlockAIOCB common;
> +    int err;
> +    int direction; /* IO direction (r/w) */

This field is unused.

> +    size_t io_offset;

This field is unused.

> +    size_t size;

This field is unused.

> +    QEMUIOVector *qiov;
> +} VXHSAIOCB;
> +
> +typedef struct VXHSvDiskHostsInfo {
> +    int qnio_cfd; /* Channel FD */
> +    int vdisk_rfd; /* vDisk remote FD */

Please don't call things FDs if they are not FDs.  This is confusing
because dup(), close(), etc don't work on them.  They are handles.

Handles are an unnecessary layer of indirection in the first place.
libqnio would be simpler if it returned opaque pointers to structs
instead.  This way hash/map lookups can be eliminated.

Instead of storing strings in the hash/map, define structs with useful
fields.  This eliminates some of the string parsing in libqnio.

> +    char *hostip; /* Host's IP addresses */

Is this strictly an IP address?  If a hostname can be used too then
"host" would be clearer name.

> +    int port; /* Host's port number */
> +} VXHSvDiskHostsInfo;
> +
> +/*
> + * Structure per vDisk maintained for state
> + */
> +typedef struct BDRVVXHSState {
> +    int fds[2];
> +    int event_reader_pos;

Why is a pipe still being used?  Back in August I mentioned that this
approach isn't the best practice anymore.  It's more code and slower
than QEMUBH.

You didn't respond to my review comment.  Feel free to disagree with my
comments but please respond so I know what to expect.  Now I'm wondering
whether other comments have been ignored too...

> +static int vxhs_qnio_iio_open(int *cfd, const char *of_vsa_addr,
> +                              int *rfd, const char *file_name)
> +{
> +    int ret = 0;
> +    bool qnio_open = false;

This variable isn't necessary since the vxhs_qnio_open() error uses
return instead of goto.


Pausing review at this point because I realized that my previous review
comments weren't addressed.

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