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Block-layer backend interface for bhyve block-io device emulations.

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Approved by:	re@ (blanket)
This commit is contained in:
Peter Grehan 2013-10-04 16:52:03 +00:00
parent 89898f63c2
commit 7cf5a7eeb0
Notes: svn2git 2020-12-20 02:59:44 +00:00 
svn path=/head/; revision=256052
2 changed files with 490 additions and 0 deletions
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426
usr.sbin/bhyve/block_if.c Normal file
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/*-
* Copyright (c) 2013 Peter Grehan <grehan@freebsd.org>
* All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* 2. Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in the
* documentation and/or other materials provided with the distribution.
*
* THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND
* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
* ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
* SUCH DAMAGE.
*
* $FreeBSD$
*/
#include <sys/cdefs.h>
__FBSDID("$FreeBSD$");
#include <sys/param.h>
#include <sys/queue.h>
#include <sys/errno.h>
#include <sys/stat.h>
#include <sys/ioctl.h>
#include <sys/disk.h>
#include <assert.h>
#include <fcntl.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <pthread.h>
#include <pthread_np.h>
#include <unistd.h>
#include "bhyverun.h"
#include "block_if.h"
#define BLOCKIF_SIG 0xb109b109
#define BLOCKIF_MAXREQ 16
enum blockop {
BOP_READ,
BOP_WRITE,
BOP_FLUSH,
BOP_CANCEL
};
enum blockstat {
BST_FREE,
BST_INUSE
};
struct blockif_elem {
TAILQ_ENTRY(blockif_elem) be_link;
struct blockif_req *be_req;
enum blockop be_op;
enum blockstat be_status;
};
struct blockif_ctxt {
int bc_magic;
int bc_fd;
int bc_rdonly;
off_t bc_size;
int bc_sectsz;
pthread_t bc_btid;
pthread_mutex_t bc_mtx;
pthread_cond_t bc_cond;
int bc_closing;
/* Request elements and free/inuse queues */
TAILQ_HEAD(, blockif_elem) bc_freeq;
TAILQ_HEAD(, blockif_elem) bc_inuseq;
u_int bc_req_count;
struct blockif_elem bc_reqs[BLOCKIF_MAXREQ];
};
static int
blockif_enqueue(struct blockif_ctxt *bc, struct blockif_req *breq,
enum blockop op)
{
struct blockif_elem *be;
assert(bc->bc_req_count < BLOCKIF_MAXREQ);
be = TAILQ_FIRST(&bc->bc_freeq);
assert(be != NULL);
assert(be->be_status == BST_FREE);
TAILQ_REMOVE(&bc->bc_freeq, be, be_link);
be->be_status = BST_INUSE;
be->be_req = breq;
be->be_op = op;
TAILQ_INSERT_TAIL(&bc->bc_inuseq, be, be_link);
bc->bc_req_count++;
return (0);
}
static int
blockif_dequeue(struct blockif_ctxt *bc, struct blockif_elem *el)
{
struct blockif_elem *be;
if (bc->bc_req_count == 0)
return (ENOENT);
be = TAILQ_FIRST(&bc->bc_inuseq);
assert(be != NULL);
assert(be->be_status == BST_INUSE);
*el = *be;
TAILQ_REMOVE(&bc->bc_inuseq, be, be_link);
be->be_status = BST_FREE;
be->be_req = NULL;
TAILQ_INSERT_TAIL(&bc->bc_freeq, be, be_link);
bc->bc_req_count--;
return (0);
}
static void
blockif_proc(struct blockif_ctxt *bc, struct blockif_elem *be)
{
struct blockif_req *br;
int err;
br = be->be_req;
err = 0;
switch (be->be_op) {
case BOP_READ:
if (preadv(bc->bc_fd, br->br_iov, br->br_iovcnt,
br->br_offset) < 0)
err = errno;
break;
case BOP_WRITE:
if (bc->bc_rdonly)
err = EROFS;
else if (pwritev(bc->bc_fd, br->br_iov, br->br_iovcnt,
br->br_offset) < 0)
err = errno;
break;
case BOP_FLUSH:
break;
case BOP_CANCEL:
err = EINTR;
break;
default:
err = EINVAL;
break;
}
(*br->br_callback)(br, err);
}
static void *
blockif_thr(void *arg)
{
struct blockif_ctxt *bc;
struct blockif_elem req;
bc = arg;
for (;;) {
pthread_mutex_lock(&bc->bc_mtx);
while (!blockif_dequeue(bc, &req)) {
pthread_mutex_unlock(&bc->bc_mtx);
blockif_proc(bc, &req);
pthread_mutex_lock(&bc->bc_mtx);
}
pthread_cond_wait(&bc->bc_cond, &bc->bc_mtx);
pthread_mutex_unlock(&bc->bc_mtx);
/*
* Check ctxt status here to see if exit requested
*/
if (bc->bc_closing)
pthread_exit(NULL);
}
/* Not reached */
return (NULL);
}
struct blockif_ctxt *
blockif_open(const char *optstr, const char *ident)
{
char tname[MAXCOMLEN + 1];
char *nopt, *xopts;
struct blockif_ctxt *bc;
struct stat sbuf;
off_t size;
int extra, fd, i, sectsz;
int nocache, sync, ro;
nocache = 0;
sync = 0;
ro = 0;
/*
* The first element in the optstring is always a pathname.
* Optional elements follow
*/
nopt = strdup(optstr);
for (xopts = strtok(nopt, ",");
xopts != NULL;
xopts = strtok(NULL, ",")) {
if (!strcmp(xopts, "nocache"))
nocache = 1;
else if (!strcmp(xopts, "sync"))
sync = 1;
else if (!strcmp(xopts, "ro"))
ro = 1;
}
extra = 0;
if (nocache)
extra |= O_DIRECT;
if (sync)
extra |= O_SYNC;
fd = open(nopt, (ro ? O_RDONLY : O_RDWR) | extra);
if (fd < 0 && !ro) {
/* Attempt a r/w fail with a r/o open */
fd = open(nopt, O_RDONLY | extra);
ro = 1;
}
if (fd < 0) {
perror("Could not open backing file");
return (NULL);
}
if (fstat(fd, &sbuf) < 0) {
perror("Could not stat backing file");
close(fd);
return (NULL);
}
/*
* Deal with raw devices
*/
size = sbuf.st_size;
sectsz = DEV_BSIZE;
if (S_ISCHR(sbuf.st_mode)) {
if (ioctl(fd, DIOCGMEDIASIZE, &size) < 0 ||
ioctl(fd, DIOCGSECTORSIZE, &sectsz)) {
perror("Could not fetch dev blk/sector size");
close(fd);
return (NULL);
}
assert(size != 0);
assert(sectsz != 0);
}
bc = malloc(sizeof(struct blockif_ctxt));
if (bc == NULL) {
close(fd);
return (NULL);
}
memset(bc, 0, sizeof(*bc));
bc->bc_magic = BLOCKIF_SIG;
bc->bc_fd = fd;
bc->bc_size = size;
bc->bc_sectsz = sectsz;
pthread_mutex_init(&bc->bc_mtx, NULL);
pthread_cond_init(&bc->bc_cond, NULL);
TAILQ_INIT(&bc->bc_freeq);
TAILQ_INIT(&bc->bc_inuseq);
bc->bc_req_count = 0;
for (i = 0; i < BLOCKIF_MAXREQ; i++) {
bc->bc_reqs[i].be_status = BST_FREE;
TAILQ_INSERT_HEAD(&bc->bc_freeq, &bc->bc_reqs[i], be_link);
}
pthread_create(&bc->bc_btid, NULL, blockif_thr, bc);
snprintf(tname, sizeof(tname), "%s blk-%s", vmname, ident);
pthread_set_name_np(bc->bc_btid, tname);
return (bc);
}
static int
blockif_request(struct blockif_ctxt *bc, struct blockif_req *breq,
enum blockop op)
{
int err;
err = 0;
pthread_mutex_lock(&bc->bc_mtx);
if (bc->bc_req_count < BLOCKIF_MAXREQ) {
/*
* Enqueue and inform the block i/o thread
* that there is work available
*/
blockif_enqueue(bc, breq, op);
pthread_cond_signal(&bc->bc_cond);
} else {
/*
* Callers are not allowed to enqueue more than
* the specified blockif queue limit. Return an
* error to indicate that the queue length has been
* exceeded.
*/
err = E2BIG;
}
pthread_mutex_unlock(&bc->bc_mtx);
return (err);
}
int
blockif_read(struct blockif_ctxt *bc, struct blockif_req *breq)
{
assert(bc->bc_magic == BLOCKIF_SIG);
return (blockif_request(bc, breq, BOP_READ));
}
int
blockif_write(struct blockif_ctxt *bc, struct blockif_req *breq)
{
assert(bc->bc_magic == BLOCKIF_SIG);
return (blockif_request(bc, breq, BOP_WRITE));
}
int
blockif_flush(struct blockif_ctxt *bc, struct blockif_req *breq)
{
assert(bc->bc_magic == BLOCKIF_SIG);
return (blockif_request(bc, breq, BOP_FLUSH));
}
int
blockif_cancel(struct blockif_ctxt *bc, struct blockif_req *breq)
{
assert(bc->bc_magic == BLOCKIF_SIG);
return (blockif_request(bc, breq, BOP_CANCEL));
}
int
blockif_close(struct blockif_ctxt *bc)
{
void *jval;
int err;
err = 0;
assert(bc->bc_magic == BLOCKIF_SIG);
/*
* Stop the block i/o thread
*/
bc->bc_closing = 1;
pthread_cond_signal(&bc->bc_cond);
pthread_join(bc->bc_btid, &jval);
/* XXX Cancel queued i/o's ??? */
/*
* Release resources
*/
bc->bc_magic = 0;
close(bc->bc_fd);
free(bc);
return (0);
}
/*
* Accessors
*/
off_t
blockif_size(struct blockif_ctxt *bc)
{
assert(bc->bc_magic == BLOCKIF_SIG);
return (bc->bc_size);
}
int
blockif_sectsz(struct blockif_ctxt *bc)
{
assert(bc->bc_magic == BLOCKIF_SIG);
return (bc->bc_sectsz);
}
int
blockif_queuesz(struct blockif_ctxt *bc)
{
assert(bc->bc_magic == BLOCKIF_SIG);
return (BLOCKIF_MAXREQ);
}
int
blockif_is_ro(struct blockif_ctxt *bc)
{
assert(bc->bc_magic == BLOCKIF_SIG);
return (bc->bc_rdonly);
}

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usr.sbin/bhyve/block_if.h Normal file
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/*-
* Copyright (c) 2013 Peter Grehan <grehan@freebsd.org>
* All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* 2. Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in the
* documentation and/or other materials provided with the distribution.
*
* THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND
* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
* ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
* SUCH DAMAGE.
*
* $FreeBSD$
*/
/*
* The block API to be used by bhyve block-device emulations. The routines
* are thread safe, with no assumptions about the context of the completion
* callback - it may occur in the caller's context, or asynchronously in
* another thread.
*/
#ifndef _BLOCK_IF_H_
#define _BLOCK_IF_H_
#include <sys/uio.h>
#include <sys/unistd.h>
#define BLOCKIF_IOV_MAX 32 /* not practical to be IOV_MAX */
struct blockif_req {
struct iovec br_iov[BLOCKIF_IOV_MAX];
int br_iovcnt;
off_t br_offset;
void (*br_callback)(struct blockif_req *req, int err);
void *br_param;
};
struct blockif_ctxt;
struct blockif_ctxt *blockif_open(const char *optstr, const char *ident);
off_t blockif_size(struct blockif_ctxt *bc);
int blockif_sectsz(struct blockif_ctxt *bc);
int blockif_queuesz(struct blockif_ctxt *bc);
int blockif_is_ro(struct blockif_ctxt *bc);
int blockif_read(struct blockif_ctxt *bc, struct blockif_req *breq);
int blockif_write(struct blockif_ctxt *bc, struct blockif_req *breq);
int blockif_flush(struct blockif_ctxt *bc, struct blockif_req *breq);
int blockif_cancel(struct blockif_ctxt *bc, struct blockif_req *breq);
int blockif_close(struct blockif_ctxt *bc);
#endif /* _BLOCK_IF_H_ */