block: gluster as block backend
From: Bharata B Rao <bhar...@linux.vnet.ibm.com>
This patch adds gluster as the new block backend in QEMU. This gives QEMU
the ability to boot VM images from gluster volumes.
Signed-off-by: Bharata B Rao <bhar...@linux.vnet.ibm.com>
---
Makefile.objs | 2
block/gluster.c | 435 +++++++++++++++++++++++++++++++++++++++++++++++++++++++
2 files changed, 436 insertions(+), 1 deletions(-)
create mode 100644 block/gluster.c
diff --git a/Makefile.objs b/Makefile.objs
index 25190ba..859b88a 100644
--- a/Makefile.objs
+++ b/Makefile.objs
@@ -59,7 +59,7 @@ block-nested-$(CONFIG_POSIX) += raw-posix.o
block-nested-$(CONFIG_LIBISCSI) += iscsi.o
block-nested-$(CONFIG_CURL) += curl.o
block-nested-$(CONFIG_RBD) += rbd.o
-block-nested-$(CONFIG_GLUSTERFS) += gluster-helpers.o
+block-nested-$(CONFIG_GLUSTERFS) += gluster-helpers.o gluster.o
block-obj-y += $(addprefix block/, $(block-nested-y))
diff --git a/block/gluster.c b/block/gluster.c
new file mode 100644
index 0000000..1566cb7
--- /dev/null
+++ b/block/gluster.c
@@ -0,0 +1,435 @@
+/*
+ * GlusterFS backend for QEMU
+ *
+ * (AIO implementation is derived from block/rbd.c)
+ *
+ * Copyright (C) 2012 Bharata B Rao <bhar...@linux.vnet.ibm.com>
+ *
+ * This work is licensed under the terms of the GNU GPL, version 2 or
+ * (at your option) any later version. See the COPYING file in the top-level
+ * directory.
+ */
+#include "block_int.h"
+#include "gluster-helpers.h"
+
+typedef void *gluster_file_t;
+
+typedef struct glusterConf {
+ char volfile[PATH_MAX];
+ char image[PATH_MAX];
+} glusterConf;
+
+typedef struct BDRVGlusterState {
+ int fds[2];
+ int open_flags;
+ gluster_file_t fd;
+ glusterfs_ctx_t *ctx;
+ int qemu_aio_count;
+ int event_reader_pos;
+ gluster_aiocb_t *event_gaiocb;
+} BDRVGlusterState;
+
+typedef struct glusterAIOCB {
+ BlockDriverAIOCB common;
+ QEMUBH *bh;
+ QEMUIOVector *qiov;
+ int ret;
+ int write;
+ char *bounce;
+ BDRVGlusterState *s;
+ int cancelled;
+ int error;
+} glusterAIOCB;
+
+#define GLUSTER_FD_READ 0
+#define GLUSTER_FD_WRITE 1
+
+/*
+ * file=protocol:volfile:image
+ */
+static int qemu_gluster_parsename(glusterConf *c, const char *filename)
+{
+ char *file = g_strdup(filename);
+ char *token, *next_token, *saveptr;
+ int ret = 0;
+
+ /* Discard the protocol */
+ token = strtok_r(file, ":", &saveptr);
+ if (!token) {
+ ret = -EINVAL;
+ goto out;
+ }
+
+ /* volfile */
+ next_token = strtok_r(NULL, ":", &saveptr);
+ if (!next_token) {
+ ret = -EINVAL;
+ goto out;
+ }
+ strncpy(c->volfile, next_token, PATH_MAX);
+
+ /* image */
+ next_token = strtok_r(NULL, ":", &saveptr);
+ if (!next_token) {
+ ret = -EINVAL;
+ goto out;
+ }
+ strncpy(c->image, next_token, PATH_MAX);
+out:
+ g_free(file);
+ return ret;
+}
+
+static void gluster_aio_bh_cb(void *opaque)
+{
+ glusterAIOCB *acb = opaque;
+
+ if (!acb->write) {
+ qemu_iovec_from_buffer(acb->qiov, acb->bounce, acb->qiov->size);
+ }
+ qemu_vfree(acb->bounce);
+ acb->common.cb(acb->common.opaque, (acb->ret > 0 ? 0 : acb->ret));
+ qemu_bh_delete(acb->bh);
+ acb->bh = NULL;
+
+ qemu_aio_release(acb);
+}
+
+static void qemu_gluster_complete_aio(gluster_aiocb_t *gaiocb)
+{
+ glusterAIOCB *acb = (glusterAIOCB *)gaiocb->opaque;
+ int64_t r;
+
+ if (acb->cancelled) {
+ qemu_vfree(acb->bounce);
+ qemu_aio_release(acb);
+ goto done;
+ }
+
+ r = gaiocb->ret;
+
+ if (acb->write) {
+ if (r < 0) {
+ acb->ret = r;
+ acb->error = 1;
+ } else if (!acb->error) {
+ acb->ret = gaiocb->size;
+ }
+ } else {
+ if (r < 0) {
+ memset(gaiocb->buf, 0, gaiocb->size);
+ acb->ret = r;
+ acb->error = 1;
+ } else if (r < gaiocb->size) {
+ memset(gaiocb->buf + r, 0, gaiocb->size - r);
+ if (!acb->error) {
+ acb->ret = gaiocb->size;
+ }
+ } else if (!acb->error) {
+ acb->ret = r;
+ }
+ }
+ acb->bh = qemu_bh_new(gluster_aio_bh_cb, acb);
+ qemu_bh_schedule(acb->bh);
+done:
+ g_free(gaiocb);
+}
+
+static void qemu_gluster_aio_event_reader(void *opaque)
+{
+ BDRVGlusterState *s = opaque;
+ ssize_t ret;
+
+ do {
+ char *p = (char *)&s->event_gaiocb;
+
+ ret = read(s->fds[GLUSTER_FD_READ], p + s->event_reader_pos,
+ sizeof(s->event_gaiocb) - s->event_reader_pos);
+ if (ret > 0) {
+ s->event_reader_pos += ret;
+ if (s->event_reader_pos == sizeof(s->event_gaiocb)) {
+ s->event_reader_pos = 0;
+ qemu_gluster_complete_aio(s->event_gaiocb);
+ s->qemu_aio_count--;
+ }
+ }
+ } while (ret < 0 && errno == EINTR);
+}
+
+static int qemu_gluster_aio_flush_cb(void *opaque)
+{
+ BDRVGlusterState *s = opaque;
+
+ return (s->qemu_aio_count > 0);
+}
+
+static int qemu_gluster_open(BlockDriverState *bs, const char *filename,
+ int bdrv_flags)
+{
+ BDRVGlusterState *s = bs->opaque;
+ glusterConf *c = g_malloc(sizeof(glusterConf));
+ int ret = -1;
+
+ if (qemu_gluster_parsename(c, filename)) {
+ goto out;
+ }
+
+ s->ctx = gluster_init(c->volfile);
+ if (!s->ctx) {
+ goto out;
+ }
+
+ /* FIX: Server client handshake takes time */
+ sleep(1);
+
+ s->open_flags |= O_BINARY;
+ s->open_flags &= ~O_ACCMODE;
+ if (bdrv_flags & BDRV_O_RDWR) {
+ s->open_flags |= O_RDWR;
+ } else {
+ s->open_flags |= O_RDONLY;
+ }
+
+ /* Use O_DSYNC for write-through caching, no flags for write-back caching,
+ * and O_DIRECT for no caching. */
+ if ((bdrv_flags & BDRV_O_NOCACHE))
+ s->open_flags |= O_DIRECT;
+ if (!(bdrv_flags & BDRV_O_CACHE_WB))
+ s->open_flags |= O_DSYNC;
+
+ s->fd = gluster_open(c->image, s->open_flags, 0);
+ if (!s->fd) {
+ goto out;
+ }
+
+ ret = qemu_pipe(s->fds);
+ if (ret < 0) {
+ goto out;
+ }
+ fcntl(s->fds[0], F_SETFL, O_NONBLOCK);
+ fcntl(s->fds[1], F_SETFL, O_NONBLOCK);
+ qemu_aio_set_fd_handler(s->fds[GLUSTER_FD_READ],
+ qemu_gluster_aio_event_reader, NULL, qemu_gluster_aio_flush_cb, s);
+out:
+ if (c) {
+ g_free(c);
+ }
+ if (ret < 0) {
+ gluster_close(s->fd);
+ }
+ return ret;
+}
+
+static int qemu_gluster_create(const char *filename,
+ QEMUOptionParameter *options)
+{
+ glusterConf *c = g_malloc(sizeof(glusterConf));
+ int ret = 0;
+ gluster_file_t fd;
+ int64_t total_size = 0;
+
+ ret = qemu_gluster_parsename(c, filename);
+ if (ret) {
+ goto out;
+ }
+
+ if (!gluster_init(c->volfile)) {
+ ret = -1;
+ goto out;
+ }
+
+ /* FIX: Server client handshake takes time */
+ sleep(1);
+
+ /* Read out options */
+ while (options && options->name) {
+ if (!strcmp(options->name, BLOCK_OPT_SIZE)) {
+ total_size = options->value.n / BDRV_SECTOR_SIZE;
+ }
+ options++;
+ }
+
+ fd = gluster_creat(c->image, 0644);
+ if (!fd) {
+ ret = -errno;
+ } else {
+ if (gluster_ftruncate(fd, total_size * BDRV_SECTOR_SIZE) != 0) {
+ ret = -errno;
+ }
+ if (gluster_close(fd) != 0) {
+ ret = -errno;
+ }
+ }
+out:
+ if (c) {
+ g_free(c);
+ }
+ return ret;
+}
+
+static AIOPool gluster_aio_pool = {
+ .aiocb_size = sizeof(glusterAIOCB),
+};
+
+static int qemu_gluster_send_pipe(BDRVGlusterState *s, gluster_aiocb_t *gaiocb)
+{
+ int ret = 0;
+ while (1) {
+ fd_set wfd;
+ int fd = s->fds[GLUSTER_FD_WRITE];
+
+ ret = write(fd, (void *)&gaiocb, sizeof(gaiocb));
+ if (ret >= 0) {
+ break;
+ }
+ if (errno == EINTR) {
+ continue;
+ }
+ if (errno != EAGAIN) {
+ break;
+ }
+
+ FD_ZERO(&wfd);
+ FD_SET(fd, &wfd);
+ do {
+ ret = select(fd + 1, NULL, &wfd, NULL, NULL);
+ } while (ret < 0 && errno == EINTR);
+ }
+ return ret;
+}
+
+static void gluster_finish_aiocb(void *arg)
+{
+ int ret;
+ gluster_aiocb_t *gaiocb = (gluster_aiocb_t *)arg;
+ BDRVGlusterState *s = ((glusterAIOCB *)gaiocb->opaque)->s;
+
+ ret = qemu_gluster_send_pipe(s, gaiocb);
+ if (ret < 0) {
+ g_free(gaiocb);
+ }
+}
+
+static BlockDriverAIOCB *qemu_gluster_aio_rw(BlockDriverState *bs,
+ int64_t sector_num, QEMUIOVector *qiov, int nb_sectors,
+ BlockDriverCompletionFunc *cb, void *opaque, int write)
+{
+ int ret;
+ glusterAIOCB *acb;
+ gluster_aiocb_t *gaiocb;
+ BDRVGlusterState *s = bs->opaque;
+ char *buf;
+ size_t size;
+ off_t offset;
+
+ acb = qemu_aio_get(&gluster_aio_pool, bs, cb, opaque);
+ acb->write = write;
+ acb->qiov = qiov;
+ acb->bounce = qemu_blockalign(bs, qiov->size);
+ acb->ret = 0;
+ acb->bh = NULL;
+ acb->s = s;
+
+ if (write) {
+ qemu_iovec_to_buffer(acb->qiov, acb->bounce);
+ }
+
+ buf = acb->bounce;
+ offset = sector_num * BDRV_SECTOR_SIZE;
+ size = nb_sectors * BDRV_SECTOR_SIZE;
+ s->qemu_aio_count++;
+
+ gaiocb = g_malloc(sizeof(gluster_aiocb_t));
+ gaiocb->opaque = acb;
+ gaiocb->buf = buf;
+ gaiocb->offset = offset;
+ gaiocb->size = size;
+ gaiocb->completion_fn = &gluster_finish_aiocb;
+
+ if (write) {
+ ret = gluster_aio_writev(s->fd, gaiocb);
+ } else {
+ ret = gluster_aio_readv(s->fd, gaiocb);
+ }
+
+ if (ret < 0) {
+ goto out;
+ }
+ return &acb->common;
+
+out:
+ g_free(gaiocb);
+ s->qemu_aio_count--;
+ qemu_aio_release(acb);
+ return NULL;
+}
+
+static BlockDriverAIOCB *qemu_gluster_aio_readv(BlockDriverState *bs,
+ int64_t sector_num, QEMUIOVector *qiov, int nb_sectors,
+ BlockDriverCompletionFunc *cb, void *opaque)
+{
+ return qemu_gluster_aio_rw(bs, sector_num, qiov, nb_sectors, cb, opaque,
0);
+}
+
+static BlockDriverAIOCB *qemu_gluster_aio_writev(BlockDriverState *bs,
+ int64_t sector_num, QEMUIOVector *qiov, int nb_sectors,
+ BlockDriverCompletionFunc *cb, void *opaque)
+{
+ return qemu_gluster_aio_rw(bs, sector_num, qiov, nb_sectors, cb, opaque,
1);
+}
+
+static int64_t qemu_gluster_getlength(BlockDriverState *bs)
+{
+ BDRVGlusterState *s = bs->opaque;
+ gluster_file_t fd = s->fd;
+ struct stat st;
+ int ret;
+
+ ret = gluster_fstat(fd, &st);
+ if (ret < 0) {
+ return -1;
+ } else {
+ return st.st_size;
+ }
+}
+
+static void qemu_gluster_close(BlockDriverState *bs)
+{
+ BDRVGlusterState *s = bs->opaque;
+
+ if (s->fd) {
+ gluster_close(s->fd);
+ s->fd = NULL;
+ }
+}
+
+static QEMUOptionParameter qemu_gluster_create_options[] = {
+ {
+ .name = BLOCK_OPT_SIZE,
+ .type = OPT_SIZE,
+ .help = "Virtual disk size"
+ },
+ { NULL }
+};
+
+static BlockDriver bdrv_gluster = {
+ .format_name = "gluster",
+ .protocol_name = "gluster",
+ .instance_size = sizeof(BDRVGlusterState),
+ .bdrv_file_open = qemu_gluster_open,
+ .bdrv_close = qemu_gluster_close,
+ .bdrv_create = qemu_gluster_create,
+ .bdrv_getlength = qemu_gluster_getlength,
+
+ .bdrv_aio_readv = qemu_gluster_aio_readv,
+ .bdrv_aio_writev = qemu_gluster_aio_writev,
+
+ .create_options = qemu_gluster_create_options,
+};
+
+static void bdrv_gluster_init(void)
+{
+ bdrv_register(&bdrv_gluster);
+}
+
+block_init(bdrv_gluster_init);
