Thanos Makatos
2013-Jan-24 12:20 UTC
[PATCH 0 of 9 RFC v3] blktap3: Introduce a small subset of blktap3 files
blktap3 is a disk back-end driver. It is based on blktap2 but does not require the blktap/blkback kernel modules as it allows tapdisk to talk directly to blkfront. This primarily simplifies maintenance, and _may_ lead to performance improvements. blktap3 is based on a blktap2 fork maintained mostly by Citrix (it lives in github), so these changes are also imported, apart from the blktap3 ones. I''ve organised my upstream effort as follows: 1. Upstream the smallest possible subset of blktap3 that will allow guest VMs to use RAW images backed by blktap3. This will enable early testing on the bits introduced by blktap3. 2. Upstream the remaining of blktap3, most notably back-end drivers, e.g. VHD etc. 3. Import bug fixes from blktap2 living in github. 4. Import new features and optimisations from blktap2 living in github, e.g. the mirroring plug-in. blktap3 is broken into patches that can be found here: https://bitbucket.org/tmakatos/blktap3-patches blktap3 is made of the following components: 1. blkfront (not a blktap3 component and already upstream): a virtual block device driver in the guest VM that receives block I/O requests and forwards them to tapdisk via the shared ring. 2. tapdisk: a user space process that receives block I/O requests from blkfront, translates them to whatever the current backing file format is (i.e. RAW, VHD, qcow etc.), and performs the actual I/O. Apart from block I/O requests, the tapdisk also allows basic management of each virtual block device, e.g. a device may be temporarily paused. tapdisk listens to a loopback socket for such commands. The tap-ctl utility (explained later) can be used for managing the tapdisk. 3. libsring (formerly known as libxenio): a user space library that implements the functionality required to access the shared ring. It is used by tapdisk to obtain the block I/O requests forwarded by the front-end, and to produce the corresponding responses. This is the very "heart" of blktap3, it''s architecture will be thoroughly explained by the patch series that introduces it. 4. tapback (formerly known as xenio): a user space daemon that acts as the back-end of each virtual block device: it monitors XenStore for the block front-end''s state changes, creates/destroys the shared ring, and instructs the tapdisk to connect to/disconnect from the shared ring. It also communicates to the block front-end required parameters (e.g. block device size in sectors) via XenStore. The tapback daemon is only involved during the set up/tear down of the connection between the two ends, it does not participate in the data path. There is one tapback daemon per back-end driver domain, though we could have a tapback daemon per guest VM or per VBD. In this prototype, the tapdisk is spawned/destroyed by libxl when a domain is created/destroyed, in the exact same way as in blktap2 (libxl uses libblktapctl for this). When tapback detects a device creation request from a front-end, it must locate the tapdisk (previously created by libxl) designated to serve this VBD. There is no particular reason for this design, we could as well have the tapback daemon spawning the tapdisk (the latter choice looks neater IMO). Opting for the latter design wouldn''t affect this patch series that much. 5. libblktapctl: a user space library where the tapdisk management functions are implemented, used by libxl and tap-ctl. 6. tap-ctl: a user space utility that allows management of the tapdisk, uses libblktapctl. This patch series introduces a small subset of files required by tapback (the tapback daemon is introduced by the next patch series): - basic blktap3 header files - a rudimentary implementation of libblktapctl. Only the bits required by tapback to manage the tapdisk are introduced, the rest of this library will be introduced by later patches. --- Changed since v1: * In all patches the patch message has been improved. * Patches 1, 5, and 6 use GPLv2. * Patch 0: Basic explanation of blktap3''s fundamental components. * Patch 9: Improved tools/blktap3/control/Makefile by moving hard coded paths to config/StdGNU.mk. Changed since v2: - Updated tapback daemon description.
Thanos Makatos
2013-Jan-24 12:20 UTC
[PATCH 1 of 9 RFC v3] blktap3: Introduce blktap3 headers
This patch introduces basic blktap3 header files.
---
Changed since v2:
* Use GPL license instead of LGPL in compiler.h.
* Removed ARRAY_SIZE macro.
* Use libxl_internal.h''s definition of containerof macro.
diff --git a/tools/blktap3/include/blktap3.h b/tools/blktap3/include/blktap3.h
new file mode 100644
--- /dev/null
+++ b/tools/blktap3/include/blktap3.h
@@ -0,0 +1,47 @@
+/*
+ * Copyright (C) 2012 Citrix Ltd.
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License
+ * as published by the Free Software Foundation; either version 2
+ * of the License, or (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301,
+ * USA.
+ *
+ * Commonly used headers and definitions.
+ */
+
+#ifndef __BLKTAP_3_H__
+#define __BLKTAP_3_H__
+
+#include "compiler.h"
+
+/* TODO remove from other files */
+#include <xen-external/bsd-sys-queue.h>
+
+#define BLKTAP3_CONTROL_NAME "blktap-control"
+#define BLKTAP3_CONTROL_DIR "/var/run/"BLKTAP3_CONTROL_NAME
+#define BLKTAP3_CONTROL_SOCKET "ctl"
+
+#define BLKTAP3_ENOSPC_SIGNAL_FILE "/var/run/tapdisk3-enospc"
+
+/*
+ * TODO They may have to change due to macro namespacing.
+ */
+#define TAILQ_MOVE_HEAD(node, src, dst, entry) \
+ TAILQ_REMOVE(src, node, entry); \
+ TAILQ_INSERT_HEAD(dst, node, entry);
+
+#define TAILQ_MOVE_TAIL(node, src, dst, entry) \
+ TAILQ_REMOVE(src, node, entry); \
+ TAILQ_INSERT_TAIL(dst, node, entry);
+
+#endif /* __BLKTAP_3_H__ */
diff --git a/tools/blktap3/include/compiler.h b/tools/blktap3/include/compiler.h
new file mode 100644
--- /dev/null
+++ b/tools/blktap3/include/compiler.h
@@ -0,0 +1,42 @@
+/*
+ * Copyright (C) 2012 Citrix Ltd.
+ *
+ * This library is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU Lesser General Public
+ * License as published by the Free Software Foundation; either
+ * version 2.1 of the License, or (at your option) any later version.
+ *
+ * This library is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
+ * Lesser General Public License for more details.
+ *
+ * You should have received a copy of the GNU Lesser General Public
+ * License along with this library; if not, write to the Free Software
+ * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301
+ * USA
+ */
+
+#ifndef __COMPILER_H__
+#define __COMPILER_H__
+
+#define likely(_cond) __builtin_expect(!!(_cond), 1)
+#define unlikely(_cond) __builtin_expect(!!(_cond), 0)
+
+#define containerof(inner_ptr, outer, member_name) \
+ ({ \
+ typeof(outer) *container_of_; \
+ container_of_ = (void*)((char*)(inner_ptr) - \
+ offsetof(typeof(outer), member_name)); \
+ (void)(&container_of_->member_name ==
\
+ (typeof(inner_ptr))0) /* type check */; \
+ container_of_; \
+ })
+
+#define __printf(a, b) __attribute__((format(printf, a, b)))
+#define __scanf(_f, _a) __attribute__((format (scanf, _f, _a)))
+
+#define UNUSED_PARAMETER(x) \
+ (void)(x);
+
+#endif /* __COMPILER_H__ */
Thanos Makatos
2013-Jan-24 12:20 UTC
[PATCH 2 of 9 RFC v3] blktap3/libblktapctl: Introduce tapdisk message types and structures
This patch introduces function prototypes and structures that are implemented
by libblktapctl (the library that allows libxl, tap-ctl, and the tapback daemon
to manage a running tapdisk process). This file is based on the existing
blktap2 file, with some changes coming from blktap2 living in github (the STATS
message, support for mirroring).
tapdisk_message_name is now neater and uses a look up table instead of a big
switch.
blktap3 introduces the following messages:
- DISK_INFO: used by xenio to communicate to blkfront via XenStore the
number of sectors and the sector size so that it can create the virtual
block device.
- XENBLKIF_CONNECT/DISCONNECT: used by the xenio daemon to instruct a
running tapdisk process to connect to the ring. The
tapdisk_message_blkif structure is used to convey such messages.
The ATTACH message has been removed since it is now superseded by
XENBLKIF_CONNECT (this probably means that DETACH must be removed as well in
favour of XENBLKIF_DISCONNECT). However, it would probably be nicer to keep the
ATTACH/DETACH identifiers in order to minimize interface changes.
---
Changed since v2:
* Include TAPDISK_MESSAGE_MAX in the enum.
* Updated comment regarding the proto member in struct tapdisk_message
blkif.
* Rearranged enum tapdisk_message_id in such a way that messages requiring a
response belong to a "group". Introduce self-explanatory function
tapdisk_message_is_rsp_paired.
diff --git a/tools/blktap2/include/tapdisk-message.h
b/tools/blktap3/include/tapdisk-message.h
copy from tools/blktap2/include/tapdisk-message.h
copy to tools/blktap3/include/tapdisk-message.h
--- a/tools/blktap2/include/tapdisk-message.h
+++ b/tools/blktap3/include/tapdisk-message.h
@@ -36,29 +36,35 @@
#define TAPDISK_MESSAGE_MAX_MINORS \
((TAPDISK_MESSAGE_MAX_PATH_LENGTH / sizeof(int)) - 1)
-#define TAPDISK_MESSAGE_FLAG_SHARED 0x01
-#define TAPDISK_MESSAGE_FLAG_RDONLY 0x02
-#define TAPDISK_MESSAGE_FLAG_ADD_CACHE 0x04
-#define TAPDISK_MESSAGE_FLAG_VHD_INDEX 0x08
-#define TAPDISK_MESSAGE_FLAG_LOG_DIRTY 0x10
+#define TAPDISK_MESSAGE_FLAG_SHARED 0x001
+#define TAPDISK_MESSAGE_FLAG_RDONLY 0x002
+#define TAPDISK_MESSAGE_FLAG_ADD_CACHE 0x004
+#define TAPDISK_MESSAGE_FLAG_VHD_INDEX 0x008
+#define TAPDISK_MESSAGE_FLAG_LOG_DIRTY 0x010
+#define TAPDISK_MESSAGE_FLAG_ADD_LCACHE 0x020
+#define TAPDISK_MESSAGE_FLAG_REUSE_PRT 0x040
+#define TAPDISK_MESSAGE_FLAG_SECONDARY 0x080
+#define TAPDISK_MESSAGE_FLAG_STANDBY 0x100
typedef struct tapdisk_message tapdisk_message_t;
-typedef uint8_t tapdisk_message_flag_t;
+typedef uint32_t tapdisk_message_flag_t;
typedef struct tapdisk_message_image tapdisk_message_image_t;
typedef struct tapdisk_message_params tapdisk_message_params_t;
typedef struct tapdisk_message_string tapdisk_message_string_t;
typedef struct tapdisk_message_response tapdisk_message_response_t;
typedef struct tapdisk_message_minors tapdisk_message_minors_t;
typedef struct tapdisk_message_list tapdisk_message_list_t;
+typedef struct tapdisk_message_stat tapdisk_message_stat_t;
+typedef struct tapdisk_message_blkif tapdisk_message_blkif_t;
struct tapdisk_message_params {
tapdisk_message_flag_t flags;
- uint8_t storage;
uint32_t devnum;
uint32_t domid;
- uint16_t path_len;
char path[TAPDISK_MESSAGE_MAX_PATH_LENGTH];
+ uint32_t prt_devnum;
+ char secondary[TAPDISK_MESSAGE_MAX_PATH_LENGTH];
};
struct tapdisk_message_image {
@@ -88,6 +94,55 @@ struct tapdisk_message_list {
char path[TAPDISK_MESSAGE_MAX_PATH_LENGTH];
};
+struct tapdisk_message_stat {
+ uint16_t type;
+ uint16_t cookie;
+ size_t length;
+};
+
+/**
+ * Tapdisk message containing all the necessary information required for the
+ * tapdisk to connect to a guest''s blkfront.
+ */
+struct tapdisk_message_blkif {
+ /**
+ * The domain ID of the guest to connect to.
+ */
+ uint32_t domid;
+
+ /**
+ * The device ID of the virtual block device.
+ */
+ uint32_t devid;
+
+ /**
+ * Grant references for the shared ring.
+ * TODO Why 8 specifically?
+ */
+ uint32_t gref[8];
+
+ /**
+ * Number of pages in the ring, expressed as a page order.
+ */
+ uint32_t order;
+
+ /**
+ * Protocol to use: native, 32 bit, or 64 bit. Used for supporting a
+ * 32-bit domU talking to a 64-bit dom0/domU and vice versa.
+ */
+ uint32_t proto;
+
+ /**
+ * TODO Page pool? Can be NULL.
+ */
+ char pool[TAPDISK_MESSAGE_STRING_LENGTH];
+
+ /**
+ * The event channel port.
+ */
+ uint32_t port;
+};
+
struct tapdisk_message {
uint16_t type;
uint16_t cookie;
@@ -100,13 +155,30 @@ struct tapdisk_message {
tapdisk_message_minors_t minors;
tapdisk_message_response_t response;
tapdisk_message_list_t list;
+ tapdisk_message_stat_t info;
+ tapdisk_message_blkif_t blkif;
} u;
};
-enum tapdisk_message_id {
+/**
+ * Messages that are paired with a response (e.g. TAPDISK_MESSAGE_FOO goes
+ * hand in hand with message TAPDISK_MESSAGE_FOO_RSP) should be placed within
+ * a contiguous range in the enum in order to be able to easily identify
+ * whether a given message requires a response. Also, a message''s
response
+ * must follow the message in the enum so that their values differ by 1.
+ */
+typedef enum tapdisk_message_id {
+ /*
+ * TODO Why start from 1 and not from 0?
+ */
TAPDISK_MESSAGE_ERROR = 1,
TAPDISK_MESSAGE_RUNTIME_ERROR,
- TAPDISK_MESSAGE_PID,
+
+ /*
+ * Begin of messages paired with a response.
+ */
+ TAPDISK_MESSAGE_REQS_RSP_START, /* not an actual message */
+ TAPDISK_MESSAGE_PID = TAPDISK_MESSAGE_REQS_RSP_START,
TAPDISK_MESSAGE_PID_RSP,
TAPDISK_MESSAGE_ATTACH,
TAPDISK_MESSAGE_ATTACH_RSP,
@@ -120,84 +192,94 @@ enum tapdisk_message_id {
TAPDISK_MESSAGE_CLOSE_RSP,
TAPDISK_MESSAGE_DETACH,
TAPDISK_MESSAGE_DETACH_RSP,
- TAPDISK_MESSAGE_LIST_MINORS,
- TAPDISK_MESSAGE_LIST_MINORS_RSP,
+ TAPDISK_MESSAGE_LIST_MINORS, /* TODO still valid? */
+ TAPDISK_MESSAGE_LIST_MINORS_RSP, /* TODO still valid? */
TAPDISK_MESSAGE_LIST,
TAPDISK_MESSAGE_LIST_RSP,
- TAPDISK_MESSAGE_FORCE_SHUTDOWN,
+ TAPDISK_MESSAGE_STATS,
+ TAPDISK_MESSAGE_STATS_RSP,
+ TAPDISK_MESSAGE_DISK_INFO,
+ TAPDISK_MESSAGE_DISK_INFO_RSP,
+ TAPDISK_MESSAGE_XENBLKIF_CONNECT,
+ TAPDISK_MESSAGE_XENBLKIF_CONNECT_RSP,
+ TAPDISK_MESSAGE_XENBLKIF_DISCONNECT,
+ TAPDISK_MESSAGE_XENBLKIF_DISCONNECT_RSP,
+ TAPDISK_MESSAGE_REQS_RSP_END = TAPDISK_MESSAGE_XENBLKIF_DISCONNECT_RSP,
+ /*
+ * End of messages requiring a response.
+ */
+
+ TAPDISK_MESSAGE_FORCE_SHUTDOWN,
TAPDISK_MESSAGE_EXIT,
-};
+ TAPDISK_MESSAGE_MAX
+} td_msg_id_t;
-static inline char *
-tapdisk_message_name(enum tapdisk_message_id id)
-{
- switch (id) {
- case TAPDISK_MESSAGE_ERROR:
- return "error";
+/**
+ * Tells whether a request message is paired with a reply message or vice
+ * versa.
+ *
+ * @param id the message ID
+ * @returns 1 if the request message is paired with a response (or vice versa),
+ * 0 otherwise
+ */
+static inline int tapdisk_message_is_rsp_paired(const td_msg_id_t id) {
+ return id >= TAPDISK_MESSAGE_REQS_RSP_START
+ && id <= TAPDISK_MESSAGE_REQS_RSP_END;
+}
- case TAPDISK_MESSAGE_PID:
- return "pid";
+/**
+ * Retrieves a message''s human-readable representation.
+ *
+ * @param id the message ID to translate
+ * @return the name of the message
+ *
+ * @note If the message type is unknown the function simply returns
''unknown'',
+ * so the information regarding the erroneous message type is lost. We could
+ * include the number of the message in the returned string but we would then
+ * have to allocate it, forcing the user to release each string this function
+ * would return, something that users of this function would probably forget
+ * to do.
+ */
+static inline char const *
+tapdisk_message_name(const td_msg_id_t id) {
+ static char const *msg_names[TAPDISK_MESSAGE_MAX] = {
+ [TAPDISK_MESSAGE_ERROR] = "error",
+ [TAPDISK_MESSAGE_RUNTIME_ERROR] = "runtime error",
+ [TAPDISK_MESSAGE_PID] = "pid",
+ [TAPDISK_MESSAGE_PID_RSP] = "pid response",
+ [TAPDISK_MESSAGE_OPEN] = "open",
+ [TAPDISK_MESSAGE_OPEN_RSP] = "open response",
+ [TAPDISK_MESSAGE_PAUSE] = "pause",
+ [TAPDISK_MESSAGE_PAUSE_RSP] = "pause response",
+ [TAPDISK_MESSAGE_RESUME] = "resume",
+ [TAPDISK_MESSAGE_RESUME_RSP] = "resume response",
+ [TAPDISK_MESSAGE_CLOSE] = "close",
+ [TAPDISK_MESSAGE_FORCE_SHUTDOWN] = "force shutdown",
+ [TAPDISK_MESSAGE_CLOSE_RSP] = "close response",
+ [TAPDISK_MESSAGE_ATTACH] = "attach",
+ [TAPDISK_MESSAGE_ATTACH_RSP] = "attach response",
+ [TAPDISK_MESSAGE_DETACH] = "detach",
+ [TAPDISK_MESSAGE_DETACH_RSP] = "detach response",
+ [TAPDISK_MESSAGE_LIST_MINORS] = "list minors",
+ [TAPDISK_MESSAGE_LIST_MINORS_RSP] = "list minors response",
+ [TAPDISK_MESSAGE_LIST] = "list",
+ [TAPDISK_MESSAGE_LIST_RSP] = "list response",
+ [TAPDISK_MESSAGE_STATS] = "stats",
+ [TAPDISK_MESSAGE_STATS_RSP] = "stats response",
+ [TAPDISK_MESSAGE_DISK_INFO] = "disk info",
+ [TAPDISK_MESSAGE_DISK_INFO_RSP] = "disk info response",
+ [TAPDISK_MESSAGE_XENBLKIF_CONNECT] = "blkif connect",
+ [TAPDISK_MESSAGE_XENBLKIF_CONNECT_RSP] = "blkif connect response",
+ [TAPDISK_MESSAGE_XENBLKIF_DISCONNECT] = "blkif disconnect",
+ [TAPDISK_MESSAGE_XENBLKIF_DISCONNECT_RSP]
+ = "blkif disconnect response",
+ [TAPDISK_MESSAGE_EXIT] = "exit"
+ };
- case TAPDISK_MESSAGE_PID_RSP:
- return "pid response";
-
- case TAPDISK_MESSAGE_OPEN:
- return "open";
-
- case TAPDISK_MESSAGE_OPEN_RSP:
- return "open response";
-
- case TAPDISK_MESSAGE_PAUSE:
- return "pause";
-
- case TAPDISK_MESSAGE_PAUSE_RSP:
- return "pause response";
-
- case TAPDISK_MESSAGE_RESUME:
- return "resume";
-
- case TAPDISK_MESSAGE_RESUME_RSP:
- return "resume response";
-
- case TAPDISK_MESSAGE_CLOSE:
- return "close";
-
- case TAPDISK_MESSAGE_FORCE_SHUTDOWN:
- return "force shutdown";
-
- case TAPDISK_MESSAGE_CLOSE_RSP:
- return "close response";
-
- case TAPDISK_MESSAGE_ATTACH:
- return "attach";
-
- case TAPDISK_MESSAGE_ATTACH_RSP:
- return "attach response";
-
- case TAPDISK_MESSAGE_DETACH:
- return "detach";
-
- case TAPDISK_MESSAGE_DETACH_RSP:
- return "detach response";
-
- case TAPDISK_MESSAGE_LIST_MINORS:
- return "list minors";
-
- case TAPDISK_MESSAGE_LIST_MINORS_RSP:
- return "list minors response";
-
- case TAPDISK_MESSAGE_LIST:
- return "list";
-
- case TAPDISK_MESSAGE_LIST_RSP:
- return "list response";
-
- case TAPDISK_MESSAGE_EXIT:
- return "exit";
-
- default:
+ if (id < 1 || id >= TAPDISK_MESSAGE_MAX) {
return "unknown";
}
+ return msg_names[id];
}
-#endif
+#endif /* _TAPDISK_MESSAGE_H_ */
Thanos Makatos
2013-Jan-24 12:20 UTC
[PATCH 3 of 9 RFC v3] blktap3/libblktapctl: Introduce the tapdisk control header
This patch introduces the header file where tapdisk control-related structures
and functions are declared. This file is based on the existing blktap2, with
most changes coming from blktap2 living in github. Linux lists are replaced by
BSD tail queues. Few functions are partly documented, most of them are not
documented at all, this will be addressed by a future patch.
diff --git a/tools/blktap2/control/tap-ctl.h b/tools/blktap3/control/tap-ctl.h
copy from tools/blktap2/control/tap-ctl.h
copy to tools/blktap3/control/tap-ctl.h
--- a/tools/blktap2/control/tap-ctl.h
+++ b/tools/blktap3/control/tap-ctl.h
@@ -30,72 +30,180 @@
#include <syslog.h>
#include <errno.h>
+#include <sys/time.h>
#include <tapdisk-message.h>
+#include "blktap3.h"
+/*
+ * TODO These are private, move to an internal header.
+ */
extern int tap_ctl_debug;
#ifdef TAPCTL
-#define DBG(_f, _a...) \
- do { \
+#define DBG(_f, _a...) \
+ do { \
if (tap_ctl_debug) \
printf(_f, ##_a); \
} while (0)
#define DPRINTF(_f, _a...) syslog(LOG_INFO, _f, ##_a)
#define EPRINTF(_f, _a...) syslog(LOG_ERR, "tap-err:%s: " _f,
__func__, ##_a)
-#define PERROR(_f, _a...) syslog(LOG_ERR, "tap-err:%s: " _f ":
%s", __func__, ##_a, \
- strerror(errno))
+#define PERROR(_f, _a...) syslog(LOG_ERR, "tap-err:%s: " _f ":
%s", \
+ __func__, ##_a, strerror(errno))
#endif
-void tap_ctl_version(int *major, int *minor);
-int tap_ctl_kernel_version(int *major, int *minor);
+/**
+ * Contains information about a tapdisk process.
+ */
+typedef struct tap_list {
-int tap_ctl_check_blktap(const char **message);
-int tap_ctl_check_version(const char **message);
-int tap_ctl_check(const char **message);
+ /**
+ * The process ID.
+ */
+ pid_t pid;
+ /**
+ * TODO
+ */
+ int minor;
+
+ /**
+ * State of the VBD, specified in drivers/tapdisk-vbd.h.
+ */
+ int state;
+
+ /**
+ * TODO
+ */
+ char *type;
+
+ /**
+ * /path/to/file
+ */
+ char *path;
+
+ /**
+ * for linked lists
+ */
+ TAILQ_ENTRY(tap_list) entry;
+} tap_list_t;
+
+TAILQ_HEAD(tqh_tap_list, tap_list);
+
+/**
+ * Iterate over a list of struct tap_list elements.
+ */
+#define tap_list_for_each_entry(_pos, _head) \
+ TAILQ_FOREACH(_pos, _head, entry)
+
+/**
+ * Iterate over a list of struct tap_list elements allowing deletions without
+ * having to restart the iteration.
+ */
+#define tap_list_for_each_entry_safe(_pos, _n, _head) \
+ TAILQ_FOREACH_SAFE(_pos, _head, entry, _n)
+
+/**
+ * Connects to a tapdisk.
+ *
+ * @param /path/to/file of the control socket (e.g.
+ * /var/run/blktap-control/ctl/<pid>
+ * @param socket output parameter that receives the connection
+ * @returns 0 on success, an error code otherwise
+ */
int tap_ctl_connect(const char *path, int *socket);
-int tap_ctl_connect_id(int id, int *socket);
-int tap_ctl_read_message(int fd, tapdisk_message_t *message, int timeout);
-int tap_ctl_write_message(int fd, tapdisk_message_t *message, int timeout);
-int tap_ctl_send_and_receive(int fd, tapdisk_message_t *message, int timeout);
-int tap_ctl_connect_send_and_receive(int id,
- tapdisk_message_t *message, int timeout);
+
+/**
+ * Connects to a tapdisk.
+ *
+ * @param id the process ID of the tapdisk to connect to
+ * @param socket output parameter that receives the connection
+ * @returns 0 on success, an error code otherwise
+ */
+int tap_ctl_connect_id(const int id, int *socket);
+
+/**
+ * Reads from the tapdisk connection to the buffer.
+ *
+ * @param fd the file descriptor of the socket to read from
+ * @param buf buffer that receives the output
+ * @param sz size, in bytes, of the buffer
+ * @param timeout (optional) specifies the maximum time to wait for reading
+ * @returns 0 on success, an error code otherwise
+ */
+int tap_ctl_read_raw(const int fd, void *buf, const size_t sz,
+ struct timeval *timeout);
+
+int tap_ctl_read_message(int fd, tapdisk_message_t * message,
+ struct timeval *timeout);
+
+int tap_ctl_write_message(int fd, tapdisk_message_t * message,
+ struct timeval *timeout);
+
+int tap_ctl_send_and_receive(int fd, tapdisk_message_t * message,
+ struct timeval *timeout);
+
+int tap_ctl_connect_send_and_receive(int id, tapdisk_message_t * message,
+ struct timeval *timeout);
+
char *tap_ctl_socket_name(int id);
-typedef struct {
- int id;
- pid_t pid;
- int minor;
- int state;
- char *type;
- char *path;
-} tap_list_t;
+int tap_ctl_list_pid(pid_t pid, struct tqh_tap_list *list);
-int tap_ctl_get_driver_id(const char *handle);
+/**
+ * Retrieves a list of all tapdisks.
+ *
+ * @param list output parameter that receives the list of tapdisks
+ * @returns 0 on success, an error code otherwise
+ */
+int tap_ctl_list(struct tqh_tap_list *list);
-int tap_ctl_list(tap_list_t ***list);
-void tap_ctl_free_list(tap_list_t **list);
-int tap_ctl_find(const char *type, const char *path, tap_list_t *tap);
+/**
+ * Deallocates a list of struct tap_list.
+ *
+ * @param list the tapdisk information structure to deallocate.
+ */
+void tap_ctl_list_free(struct tqh_tap_list *list);
-int tap_ctl_allocate(int *minor, char **devname);
-int tap_ctl_free(const int minor);
+/**
+ * Creates a tapdisk process.
+ *
+ * TODO document parameters
+ * @param params
+ * @param flags
+ * @param prt_minor
+ * @param secondary
+ * @returns 0 on success, en error code otherwise
+ */
+int tap_ctl_create(const char *params, int flags, int prt_minor,
+ char *secondary);
-int tap_ctl_create(const char *params, char **devname);
-int tap_ctl_destroy(const int id, const int minor);
+int tap_ctl_destroy(const int id, const int minor, int force,
+ struct timeval *timeout);
+/*
+ * TODO The following functions are not currently used by anything else
+ * other than the tapdisk itself. Move to a private header?
+ */
int tap_ctl_spawn(void);
pid_t tap_ctl_get_pid(const int id);
int tap_ctl_attach(const int id, const int minor);
int tap_ctl_detach(const int id, const int minor);
-int tap_ctl_open(const int id, const int minor, const char *params);
-int tap_ctl_close(const int id, const int minor, const int force);
+int tap_ctl_open(const int id, const int minor, const char *params,
+ int flags, const int prt_minor, const char *secondary);
-int tap_ctl_pause(const int id, const int minor);
+int tap_ctl_close(const int id, const int minor, const int force,
+ struct timeval *timeout);
+
+int tap_ctl_pause(const int id, const int minor, struct timeval
+ *timeout);
+
int tap_ctl_unpause(const int id, const int minor, const char *params);
-int tap_ctl_blk_major(void);
+ssize_t tap_ctl_stats(pid_t pid, int minor, char *buf, size_t size);
-#endif
+int tap_ctl_stats_fwrite(pid_t pid, int minor, FILE * out);
+
+#endif /* __TAP_CTL_H__ */
Thanos Makatos
2013-Jan-24 12:20 UTC
[PATCH 4 of 9 RFC v3] blktap3/libblktapctl: Introduce listing running tapdisks functionality
This patch introduces tap-ctl-list.c, the file where listing tapdisks
functionality is implemented. It is based on the existing blktap2 file with
most changes coming from blktap2 living in github. I have not examined the
changes in detail but it seems they are minor.
Function tap_ctl_list needs to be amended because minors are not retrieved
from sysfs (there''s no sysfs blktap directory any more).
diff --git a/tools/blktap2/control/tap-ctl-list.c
b/tools/blktap3/control/tap-ctl-list.c
copy from tools/blktap2/control/tap-ctl-list.c
copy to tools/blktap3/control/tap-ctl-list.c
--- a/tools/blktap2/control/tap-ctl-list.c
+++ b/tools/blktap3/control/tap-ctl-list.c
@@ -34,23 +34,47 @@
#include <glob.h>
#include "tap-ctl.h"
-#include "blktap2.h"
-#include "list.h"
+#include "blktap3.h"
+
+/**
+ * Allocates and initializes a tap_list_t.
+ */
+static tap_list_t *
+_tap_list_alloc(void)
+{
+ const size_t sz = sizeof(tap_list_t);
+ tap_list_t *tl;
+
+ tl = malloc(sz);
+ if (!tl)
+ return NULL;
+
+ tl->pid = -1;
+ tl->minor = -1;
+ tl->state = -1;
+ tl->type = NULL;
+ tl->path = NULL;
+
+ return tl;
+}
static void
-free_list(tap_list_t *entry)
+_tap_list_free(tap_list_t * tl, struct tqh_tap_list *list)
{
- if (entry->type) {
- free(entry->type);
- entry->type = NULL;
+ if (tl->type) {
+ free(tl->type);
+ tl->type = NULL;
}
- if (entry->path) {
- free(entry->path);
- entry->path = NULL;
+ if (tl->path) {
+ free(tl->path);
+ tl->path = NULL;
}
- free(entry);
+ if (list)
+ TAILQ_REMOVE(list, tl, entry);
+
+ free(tl);
}
int
@@ -66,7 +90,7 @@ int
len = ptr - params;
*type = strndup(params, len);
- *path = strdup(params + len + 1);
+ *path = strdup(params + len + 1);
if (!*type || !*path) {
free(*type);
@@ -81,102 +105,26 @@ int
return 0;
}
-static int
-init_list(tap_list_t *entry,
- int tap_id, pid_t tap_pid, int vbd_minor, int vbd_state,
- const char *params)
+void
+tap_ctl_list_free(struct tqh_tap_list *list)
{
- int err = 0;
+ tap_list_t *tl, *n;
- entry->id = tap_id;
- entry->pid = tap_pid;
- entry->minor = vbd_minor;
- entry->state = vbd_state;
-
- if (params)
- err = _parse_params(params, &entry->type, &entry->path);
-
- return err;
-}
-
-void
-tap_ctl_free_list(tap_list_t **list)
-{
- tap_list_t **_entry;
-
- for (_entry = list; *_entry != NULL; ++_entry)
- free_list(*_entry);
-
- free(list);
-}
-
-static tap_list_t**
-tap_ctl_alloc_list(int n)
-{
- tap_list_t **list, *entry;
- size_t size;
- int i;
-
- size = sizeof(tap_list_t*) * (n+1);
- list = malloc(size);
- if (!list)
- goto fail;
-
- memset(list, 0, size);
-
- for (i = 0; i < n; ++i) {
- tap_list_t *entry;
-
- entry = malloc(sizeof(tap_list_t));
- if (!entry)
- goto fail;
-
- memset(entry, 0, sizeof(tap_list_t));
-
- list[i] = entry;
- }
-
- return list;
-
-fail:
- if (list)
- tap_ctl_free_list(list);
-
- return NULL;
-}
-
-static int
-tap_ctl_list_length(const tap_list_t **list)
-{
- const tap_list_t **_entry;
- int n;
-
- n = 0;
- for (_entry = list; *_entry != NULL; ++_entry)
- n++;
-
- return n;
-}
-
-static int
-_tap_minor_cmp(const void *a, const void *b)
-{
- return *(int*)a - *(int*)b;
+ tap_list_for_each_entry_safe(tl, n, list)
+ _tap_list_free(tl, list);
}
int
-_tap_ctl_find_minors(int **_minorv)
+_tap_ctl_find_tapdisks(struct tqh_tap_list *list)
{
- glob_t glbuf = { 0 };
+ glob_t glbuf = { 0 };
const char *pattern, *format;
- int *minorv = NULL, n_minors = 0;
- int err, i;
+ int err, i, n_taps = 0;
- pattern = BLKTAP2_SYSFS_DIR"/blktap*";
- format = BLKTAP2_SYSFS_DIR"/blktap%d";
+ pattern = BLKTAP3_CONTROL_DIR "/" BLKTAP3_CONTROL_SOCKET
"*";
+ format = BLKTAP3_CONTROL_DIR "/" BLKTAP3_CONTROL_SOCKET
"%d";
- n_minors = 0;
- minorv = NULL;
+ TAILQ_INIT(list);
err = glob(pattern, 0, NULL, &glbuf);
switch (err) {
@@ -186,337 +134,231 @@ int
case GLOB_ABORTED:
case GLOB_NOSPACE:
err = -errno;
- EPRINTF("%s: glob failed, err %d", pattern, err);
- goto fail;
- }
-
- minorv = malloc(sizeof(int) * glbuf.gl_pathc);
- if (!minorv) {
- err = -errno;
+ EPRINTF("%s: glob failed: %s", pattern, strerror(err));
goto fail;
}
for (i = 0; i < glbuf.gl_pathc; ++i) {
+ tap_list_t *tl;
int n;
- n = sscanf(glbuf.gl_pathv[i], format, &minorv[n_minors]);
+ tl = _tap_list_alloc();
+ if (!tl) {
+ err = -ENOMEM;
+ goto fail;
+ }
+
+ n = sscanf(glbuf.gl_pathv[i], format, &tl->pid);
if (n != 1)
- continue;
+ goto skip;
- n_minors++;
+ tl->pid = tap_ctl_get_pid(tl->pid);
+ if (tl->pid < 0)
+ goto skip;
+
+ TAILQ_INSERT_TAIL(list, tl, entry);
+ n_taps++;
+ continue;
+
+ skip:
+ _tap_list_free(tl, NULL);
}
- qsort(minorv, n_minors, sizeof(int), _tap_minor_cmp);
-
-done:
- *_minorv = minorv;
+ done:
err = 0;
-
-out:
- if (glbuf.gl_pathv)
- globfree(&glbuf);
-
- return err ? : n_minors;
-
-fail:
- if (minorv)
- free(minorv);
-
- goto out;
-}
-
-struct tapdisk {
- int id;
- pid_t pid;
- struct list_head list;
-};
-
-static int
-_tap_tapdisk_cmp(const void *a, const void *b)
-{
- return ((struct tapdisk*)a)->id - ((struct tapdisk*)b)->id;
-}
-
-int
-_tap_ctl_find_tapdisks(struct tapdisk **_tapv)
-{
- glob_t glbuf = { 0 };
- const char *pattern, *format;
- struct tapdisk *tapv = NULL;
- int err, i, n_taps = 0;
-
- pattern = BLKTAP2_CONTROL_DIR"/"BLKTAP2_CONTROL_SOCKET"*";
- format =
BLKTAP2_CONTROL_DIR"/"BLKTAP2_CONTROL_SOCKET"%d";
-
- n_taps = 0;
- tapv = NULL;
-
- err = glob(pattern, 0, NULL, &glbuf);
- switch (err) {
- case GLOB_NOMATCH:
- goto done;
-
- case GLOB_ABORTED:
- case GLOB_NOSPACE:
- err = -errno;
- EPRINTF("%s: glob failed, err %d", pattern, err);
- goto fail;
- }
-
- tapv = malloc(sizeof(struct tapdisk) * glbuf.gl_pathc);
- if (!tapv) {
- err = -errno;
- goto fail;
- }
-
- for (i = 0; i < glbuf.gl_pathc; ++i) {
- struct tapdisk *tap;
- int n;
-
- tap = &tapv[n_taps];
-
- err = sscanf(glbuf.gl_pathv[i], format, &tap->id);
- if (err != 1)
- continue;
-
- tap->pid = tap_ctl_get_pid(tap->id);
- if (tap->pid < 0)
- continue;
-
- n_taps++;
- }
-
- qsort(tapv, n_taps, sizeof(struct tapdisk), _tap_tapdisk_cmp);
-
- for (i = 0; i < n_taps; ++i)
- INIT_LIST_HEAD(&tapv[i].list);
-
-done:
- *_tapv = tapv;
- err = 0;
-
-out:
+ out:
if (glbuf.gl_pathv)
globfree(&glbuf);
return err ? : n_taps;
-fail:
- if (tapv)
- free(tapv);
-
+ fail:
+ tap_ctl_list_free(list);
goto out;
}
-struct tapdisk_list {
- int minor;
- int state;
- char *params;
- struct list_head entry;
-};
-
-int
-_tap_ctl_list_tapdisk(int id, struct list_head *_list)
+/**
+ * Retrieves all the VBDs a tapdisk is serving.
+ *
+ * @param pid the process ID of the tapdisk whose VBDs should be retrieved
+ * @param list output parameter that receives the list of VBD
+ * @returns 0 on success, an error code otherwise
+ */
+static int
+_tap_ctl_list_tapdisk(pid_t pid, struct tqh_tap_list *list)
{
+ struct timeval timeout = {.tv_sec = 10,.tv_usec = 0 };
tapdisk_message_t message;
- struct list_head list;
- struct tapdisk_list *tl, *next;
+ tap_list_t *tl;
int err, sfd;
- err = tap_ctl_connect_id(id, &sfd);
+ err = tap_ctl_connect_id(pid, &sfd);
if (err)
return err;
memset(&message, 0, sizeof(message));
- message.type = TAPDISK_MESSAGE_LIST;
+ message.type = TAPDISK_MESSAGE_LIST;
message.cookie = -1;
- err = tap_ctl_write_message(sfd, &message, 2);
+ err = tap_ctl_write_message(sfd, &message, &timeout);
if (err)
return err;
- INIT_LIST_HEAD(&list);
+ TAILQ_INIT(list);
+
do {
- err = tap_ctl_read_message(sfd, &message, 2);
+ err = tap_ctl_read_message(sfd, &message, &timeout);
if (err) {
err = -EPROTO;
- break;
+ goto fail;
}
if (message.u.list.count == 0)
break;
- tl = malloc(sizeof(struct tapdisk_list));
+ tl = _tap_list_alloc();
if (!tl) {
err = -ENOMEM;
- break;
+ goto fail;
}
- tl->minor = message.u.list.minor;
- tl->state = message.u.list.state;
+ tl->pid = pid;
+ tl->minor = message.u.list.minor;
+ tl->state = message.u.list.state;
+
if (message.u.list.path[0] != 0) {
- tl->params = strndup(message.u.list.path,
- sizeof(message.u.list.path));
- if (!tl->params) {
- err = -errno;
- break;
+ err = _parse_params(message.u.list.path, &tl->type,
&tl->path);
+ if (err) {
+ _tap_list_free(tl, NULL);
+ goto fail;
}
- } else
- tl->params = NULL;
+ }
- list_add(&tl->entry, &list);
+ TAILQ_INSERT_HEAD(list, tl, entry);
} while (1);
- if (err)
- list_for_each_entry_safe(tl, next, &list, entry) {
- list_del(&tl->entry);
- free(tl->params);
- free(tl);
- }
+ err = 0;
+ out:
+ close(sfd);
+ return 0;
- close(sfd);
- list_splice(&list, _list);
- return err;
-}
-
-void
-_tap_ctl_free_tapdisks(struct tapdisk *tapv, int n_taps)
-{
- struct tapdisk *tap;
-
- for (tap = tapv; tap < &tapv[n_taps]; ++tap) {
- struct tapdisk_list *tl, *next;
-
- list_for_each_entry_safe(tl, next, &tap->list, entry) {
- free(tl->params);
- free(tl);
- }
- }
-
- free(tapv);
+ fail:
+ tap_ctl_list_free(list);
+ goto out;
}
int
-_tap_list_join3(int n_minors, int *minorv, int n_taps, struct tapdisk *tapv,
- tap_list_t ***_list)
+tap_ctl_list(struct tqh_tap_list *list)
{
- tap_list_t **list, **_entry, *entry;
- int i, _m, err;
+ struct tqh_tap_list minors, tapdisks, vbds;
+ tap_list_t *t, *next_t, *v, *next_v, *m, *next_m;
+ int err;
- list = tap_ctl_alloc_list(n_minors + n_taps);
- if (!list) {
- err = -ENOMEM;
+ /*
+ * Find all minors, find all tapdisks, then list all minors
+ * they attached to. Output is a 3-way outer join.
+ */
+ TAILQ_INIT(&minors);
+
+ /*
+ * TODO There''s no blktap sysfs entry anymore, get rid of minors and
+ * rationalise the rest of this function.
+ */
+#if 0
+ err = _tap_ctl_find_minors(&minors);
+ if (err < 0) {
+ EPRINTF("error finding minors: %s\n", strerror(err));
+ goto fail;
+ }
+#endif
+
+ err = _tap_ctl_find_tapdisks(&tapdisks);
+ if (err < 0) {
+ EPRINTF("error finding tapdisks: %s\n", strerror(err));
goto fail;
}
- _entry = list;
+ TAILQ_INIT(list);
- for (i = 0; i < n_taps; ++i) {
- struct tapdisk *tap = &tapv[i];
- struct tapdisk_list *tl;
+ tap_list_for_each_entry_safe(t, next_t, &tapdisks) {
- /* orphaned tapdisk */
- if (list_empty(&tap->list)) {
- err = init_list(*_entry++, tap->id, tap->pid, -1, -1, NULL);
- if (err)
- goto fail;
+ err = _tap_ctl_list_tapdisk(t->pid, &vbds);
+
+ /*
+ * TODO Don''t just swallow the error, print a warning, at least.
+ */
+ if (err || TAILQ_EMPTY(&vbds)) {
+ TAILQ_MOVE_TAIL(t, &tapdisks, list, entry);
continue;
}
- list_for_each_entry(tl, &tap->list, entry) {
+ tap_list_for_each_entry_safe(v, next_v, &vbds) {
- err = init_list(*_entry++,
- tap->id, tap->pid,
- tl->minor, tl->state, tl->params);
- if (err)
- goto fail;
+ tap_list_for_each_entry_safe(m, next_m, &minors)
+ if (m->minor == v->minor) {
+ _tap_list_free(m, &minors);
+ break;
+ }
- if (tl->minor >= 0) {
- /* clear minor */
- for (_m = 0; _m < n_minors; ++_m) {
- if (minorv[_m] == tl->minor) {
- minorv[_m] = -1;
- break;
- }
- }
- }
+ TAILQ_MOVE_TAIL(v, &vbds, list, entry);
}
+
+ _tap_list_free(t, &tapdisks);
}
/* orphaned minors */
- for (_m = 0; _m < n_minors; ++_m) {
- int minor = minorv[_m];
- if (minor >= 0) {
- err = init_list(*_entry++, -1, -1, minor, -1, NULL);
- if (err)
- goto fail;
- }
- }
-
- /* free extraneous list entries */
- for (; *_entry != NULL; ++entry) {
- free_list(*_entry);
- *_entry = NULL;
- }
-
- *_list = list;
+ TAILQ_CONCAT(list, &minors, entry);
return 0;
fail:
- if (list)
- tap_ctl_free_list(list);
+ tap_ctl_list_free(list);
+
+ tap_ctl_list_free(&vbds);
+ tap_ctl_list_free(&tapdisks);
+ tap_ctl_list_free(&minors);
return err;
}
int
-tap_ctl_list(tap_list_t ***list)
+tap_ctl_list_pid(pid_t pid, struct tqh_tap_list *list)
{
- int n_taps, n_minors, err, *minorv;
- struct tapdisk *tapv, *tap;
+ tap_list_t *t;
+ int err;
- n_taps = -1;
- n_minors = -1;
+ t = _tap_list_alloc();
+ if (!t)
+ return -ENOMEM;
- err = n_minors = _tap_ctl_find_minors(&minorv);
- if (err < 0)
- goto out;
-
- err = n_taps = _tap_ctl_find_tapdisks(&tapv);
- if (err < 0)
- goto out;
-
- for (tap = tapv; tap < &tapv[n_taps]; ++tap) {
- err = _tap_ctl_list_tapdisk(tap->id, &tap->list);
- if (err)
- goto out;
+ t->pid = tap_ctl_get_pid(pid);
+ if (t->pid < 0) {
+ _tap_list_free(t, NULL);
+ return 0;
}
- err = _tap_list_join3(n_minors, minorv, n_taps, tapv, list);
+ err = _tap_ctl_list_tapdisk(t->pid, list);
-out:
- if (n_taps > 0)
- _tap_ctl_free_tapdisks(tapv, n_taps);
+ if (err || TAILQ_EMPTY(list))
+ TAILQ_INSERT_TAIL(list, t, entry);
- if (n_minors > 0)
- free(minorv);
-
- return err;
+ return 0;
}
int
-tap_ctl_find(const char *type, const char *path, tap_list_t *tap)
+tap_ctl_find_minor(const char *type, const char *path)
{
- tap_list_t **list, **_entry;
- int ret = -ENOENT, err;
+ struct tqh_tap_list list = TAILQ_HEAD_INITIALIZER(list);
+ tap_list_t *entry;
+ int minor, err;
err = tap_ctl_list(&list);
if (err)
return err;
- for (_entry = list; *_entry != NULL; ++_entry) {
- tap_list_t *entry = *_entry;
+ minor = -1;
+
+ tap_list_for_each_entry(entry, &list) {
if (type && (!entry->type || strcmp(entry->type, type)))
continue;
@@ -524,13 +366,11 @@ tap_ctl_find(const char *type, const cha
if (path && (!entry->path || strcmp(entry->path, path)))
continue;
- *tap = *entry;
- tap->type = tap->path = NULL;
- ret = 0;
+ minor = entry->minor;
break;
}
- tap_ctl_free_list(list);
+ tap_ctl_list_free(&list);
- return ret;
+ return minor >= 0 ? minor : -ENOENT;
}
Thanos Makatos
2013-Jan-24 12:20 UTC
[PATCH 5 of 9 RFC v3] blktap3/libblktapctl: Introduce functionality used by tapback to instruct tapdisk to connect to the sring
This patch introduces functions tap_ctl_connect_xenblkif and
tap_ctl_disconnect_xenblkif, that are used by the tapback daemon to instruct a
running tapdisk process to connect to/disconnect from the shared ring.
---
Changed since v2:
* Simplified error-checking after calling tap_ctl_connect_send_and_receive.
diff --git a/tools/blktap3/control/tap-ctl-xen.c
b/tools/blktap3/control/tap-ctl-xen.c
new file mode 100644
--- /dev/null
+++ b/tools/blktap3/control/tap-ctl-xen.c
@@ -0,0 +1,80 @@
+/*
+ * Copyright (C) 2012 Citrix Ltd.
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License
+ * as published by the Free Software Foundation; either version 2
+ * of the License, or (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301,
+ * USA.
+ */
+
+#include <stdio.h>
+#include <string.h>
+
+#include "tap-ctl.h"
+#include "tap-ctl-xen.h"
+
+int tap_ctl_connect_xenblkif(pid_t pid, int minor, domid_t domid,
+ int devid, const grant_ref_t * grefs, int order,
+ const evtchn_port_t port, int proto, const char *pool)
+{
+ tapdisk_message_t message;
+ int i, err;
+
+ memset(&message, 0, sizeof(message));
+ message.type = TAPDISK_MESSAGE_XENBLKIF_CONNECT;
+ message.cookie = minor;
+
+ message.u.blkif.domid = domid;
+ message.u.blkif.devid = devid;
+ for (i = 0; i < 1 << order; i++)
+ message.u.blkif.gref[i] = grefs[i];
+ message.u.blkif.order = order;
+ message.u.blkif.port = port;
+ message.u.blkif.proto = proto;
+ if (pool)
+ strncpy(message.u.blkif.pool, pool, sizeof(message.u.blkif.pool));
+ else
+ message.u.blkif.pool[0] = 0;
+
+ err = tap_ctl_connect_send_and_receive(pid, &message, NULL);
+ if (err)
+ /*
+ * TODO include more info
+ */
+ EPRINTF("failed to connect tapdisk %d to the ring: %s\n",
pid,
+ strerror(err));
+ return err;
+}
+
+int tap_ctl_disconnect_xenblkif(pid_t pid, int minor, domid_t domid,
+ int devid, struct timeval *timeout)
+{
+ tapdisk_message_t message;
+ int err;
+
+ memset(&message, 0, sizeof(message));
+ message.type = TAPDISK_MESSAGE_XENBLKIF_DISCONNECT;
+ message.cookie = minor;
+ message.u.blkif.domid = domid;
+ message.u.blkif.devid = devid;
+
+ err = tap_ctl_connect_send_and_receive(pid, &message, timeout);
+ if (err)
+ /*
+ * TODO include more info
+ */
+ EPRINTF("failed to disconnect tapdisk %d from the ring:
%s\n", pid,
+ strerror(err));
+
+ return err;
+}
diff --git a/tools/blktap3/control/tap-ctl-xen.h
b/tools/blktap3/control/tap-ctl-xen.h
new file mode 100644
--- /dev/null
+++ b/tools/blktap3/control/tap-ctl-xen.h
@@ -0,0 +1,61 @@
+/*
+ * Copyright (C) 2012 Citrix Ltd.
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License
+ * as published by the Free Software Foundation; either version 2
+ * of the License, or (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301,
+ * USA.
+ */
+
+#ifndef __TAP_CTL_XEN_H__
+#define __TAP_CTL_XEN_H__
+
+#include <xen/xen.h>
+#include <xen/grant_table.h>
+#include <xen/event_channel.h>
+
+/**
+ * Instructs a tapdisk to connect to the shared ring.
+ *
+ * TODO further explain parameters
+ *
+ * @param pid the process ID of the tapdisk that should connect to the shared
+ * ring
+ * @param minor the minor number of the virtual block device
+ * @param domid the domain ID of the guest VM
+ * @param devid the device ID
+ * @param grefs the grant references
+ * @param order number of grant references, expressed as a 2''s order
+ * @param port event channel port
+ * @param proto the protocol: native (XENIO_BLKIF_PROTO_NATIVE),
+ * x86 (XENIO_BLKIF_PROTO_X86_32), or x64 (XENIO_BLKIF_PROTO_X86_64)
+ * @param pool TODO page pool?
+ * @returns 0 on success, an error code otherwise
+ */
+int tap_ctl_connect_xenblkif(pid_t pid, int minor, domid_t domid, int devid,
+ const grant_ref_t * grefs, int order, evtchn_port_t port, int proto,
+ const char *pool);
+
+/**
+ * Instructs a tapdisk to disconnect from the shared ring.
+ *
+ * @param pid the process ID of the tapdisk that should disconnect
+ * @param minor the minor number of the virtual block device
+ * @param domid the ID of the guest VM
+ * @param devid the device ID of the virtual block device
+ * @param timeout timeout to wait, if NULL the function will wait indefinitely
+ */
+int tap_ctl_disconnect_xenblkif(pid_t pid, int minor, domid_t domid,
+ int devid, struct timeval *timeout);
+
+#endif /* __TAP_CTL_XEN_H__ */
Thanos Makatos
2013-Jan-24 12:20 UTC
[PATCH 6 of 9 RFC v3] blktap3/libblktapctl: Introduce block device control information retrieval functionality
This patch introduces function tap_ctl_info. It is used by the tapback daemon
to retrieve the size of the block device, as well as the sector size, in order
to communicate it to blkfront so that it can create the virtual block device.
---
Changed since v2:
* Simplified error checking after calling tap_ctl_connect_send_and_receive.
diff --git a/tools/blktap3/control/tap-ctl-info.c
b/tools/blktap3/control/tap-ctl-info.c
new file mode 100644
--- /dev/null
+++ b/tools/blktap3/control/tap-ctl-info.c
@@ -0,0 +1,52 @@
+/*
+ * Copyright (C) 2012 Citrix Ltd.
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License
+ * as published by the Free Software Foundation; either version 2
+ * of the License, or (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301,
+ * USA.
+ */
+
+#include <stdio.h>
+#include <string.h>
+#include <assert.h>
+
+#include "tap-ctl.h"
+#include "tap-ctl-info.h"
+
+int tap_ctl_info(pid_t pid, int minor, unsigned long long *sectors,
+ unsigned int *sector_size, unsigned int *info)
+{
+ tapdisk_message_t message;
+ int err;
+
+ assert(sectors);
+ assert(sector_size);
+ assert(info);
+
+ memset(&message, 0, sizeof(message));
+ message.type = TAPDISK_MESSAGE_DISK_INFO;
+ message.cookie = minor;
+
+ err = tap_ctl_connect_send_and_receive(pid, &message, NULL);
+ if (err) {
+ EPRINTF("failed to get info from tapdisk %d: %s\n", pid,
+ strerror(err));
+ return err;
+ }
+
+ *sectors = message.u.image.sectors;
+ *sector_size = message.u.image.sector_size;
+ *info = message.u.image.info;
+ return err;
+}
diff --git a/tools/blktap3/control/tap-ctl-info.h
b/tools/blktap3/control/tap-ctl-info.h
new file mode 100644
--- /dev/null
+++ b/tools/blktap3/control/tap-ctl-info.h
@@ -0,0 +1,36 @@
+/*
+ * Copyright (C) 2012 Citrix Ltd.
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License
+ * as published by the Free Software Foundation; either version 2
+ * of the License, or (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301,
+ * USA.
+ */
+
+#ifndef __TAP_CTL_INFO_H__
+#define __TAP_CTL_INFO_H__
+
+/**
+ * Retrieves virtual disk information from a tapdisk.
+ *
+ * @pid the process ID of the tapdisk process
+ * @minor the minor device number
+ * @sectors output parameter that receives the number of sectors
+ * @sector_size output parameter that receives the size of the sector
+ * @info TODO ?
+ *
+ */
+int tap_ctl_info(pid_t pid, int minor, unsigned long long *sectors,
+ unsigned int *sector_size, unsigned int *info);
+
+#endif /* __TAP_CTL_INFO_H__ */
Thanos Makatos
2013-Jan-24 12:20 UTC
[PATCH 7 of 9 RFC v3] blktap3/libblktapctl: Introduce tapdisk message exchange functionality
This patch introduces file conrol/tap-ctl-ipc.c, where the functionality of
talking to a tapdisk process is implemented. This file is imported from the
existing blktap2 implementation, with most changes coming from blktap2 living
in github.
---
Changed since v2:
* Check for unexpected response in tap_ctl_send_and_receive.
* If the message has been served but an error occurred, the error in the
message is returned by the function in order to simplify error
checking/handling by the caller.
diff --git a/tools/blktap2/control/tap-ctl-ipc.c
b/tools/blktap3/control/tap-ctl-ipc.c
copy from tools/blktap2/control/tap-ctl-ipc.c
copy to tools/blktap3/control/tap-ctl-ipc.c
--- a/tools/blktap2/control/tap-ctl-ipc.c
+++ b/tools/blktap3/control/tap-ctl-ipc.c
@@ -30,44 +30,34 @@
#include <unistd.h>
#include <stdlib.h>
#include <string.h>
+#include <fcntl.h>
#include <sys/un.h>
#include <sys/stat.h>
#include <sys/types.h>
#include <sys/socket.h>
+#include <assert.h>
#include "tap-ctl.h"
-#include "blktap2.h"
+#include "blktap3.h"
int tap_ctl_debug = 0;
int
-tap_ctl_read_message(int fd, tapdisk_message_t *message, int timeout)
+tap_ctl_read_raw(int fd, void *buf, size_t size, struct timeval *timeout)
{
fd_set readfds;
- int ret, len, offset;
- struct timeval tv, *t;
+ size_t offset = 0;
+ int ret;
- t = NULL;
- offset = 0;
- len = sizeof(tapdisk_message_t);
-
- if (timeout) {
- tv.tv_sec = timeout;
- tv.tv_usec = 0;
- t = &tv;
- }
-
- memset(message, 0, sizeof(tapdisk_message_t));
-
- while (offset < len) {
+ while (offset < size) {
FD_ZERO(&readfds);
FD_SET(fd, &readfds);
- ret = select(fd + 1, &readfds, NULL, NULL, t);
+ ret = select(fd + 1, &readfds, NULL, NULL, timeout);
if (ret == -1)
break;
else if (FD_ISSET(fd, &readfds)) {
- ret = read(fd, message + offset, len - offset);
+ ret = read(fd, buf + offset, size - offset);
if (ret <= 0)
break;
offset += ret;
@@ -75,34 +65,24 @@ tap_ctl_read_message(int fd, tapdisk_mes
break;
}
- if (offset != len) {
- EPRINTF("failure reading message\n");
+ if (offset != size) {
+ EPRINTF("failure reading data %zd/%zd\n", offset, size);
return -EIO;
}
- DBG("received ''%s'' message (uuid = %u)\n",
- tapdisk_message_name(message->type), message->cookie);
-
return 0;
}
int
-tap_ctl_write_message(int fd, tapdisk_message_t *message, int timeout)
+tap_ctl_write_message(int fd, tapdisk_message_t * message,
+ struct timeval *timeout)
{
fd_set writefds;
int ret, len, offset;
- struct timeval tv, *t;
- t = NULL;
offset = 0;
len = sizeof(tapdisk_message_t);
- if (timeout) {
- tv.tv_sec = timeout;
- tv.tv_usec = 0;
- t = &tv;
- }
-
DBG("sending ''%s'' message (uuid = %u)\n",
tapdisk_message_name(message->type), message->cookie);
@@ -113,7 +93,7 @@ tap_ctl_write_message(int fd, tapdisk_me
/* we don''t bother reinitializing tv. at worst, it will wait a
* bit more time than expected. */
- ret = select(fd + 1, NULL, &writefds, NULL, t);
+ ret = select(fd + 1, NULL, &writefds, NULL, timeout);
if (ret == -1)
break;
else if (FD_ISSET(fd, &writefds)) {
@@ -134,9 +114,15 @@ tap_ctl_write_message(int fd, tapdisk_me
}
int
-tap_ctl_send_and_receive(int sfd, tapdisk_message_t *message, int timeout)
+tap_ctl_send_and_receive(const int sfd, tapdisk_message_t * const message,
+ struct timeval *timeout)
{
int err;
+ td_msg_id_t msg_type;
+
+ assert(message);
+
+ msg_type = message->type;
err = tap_ctl_write_message(sfd, message, timeout);
if (err) {
@@ -147,12 +133,29 @@ tap_ctl_send_and_receive(int sfd, tapdis
err = tap_ctl_read_message(sfd, message, timeout);
if (err) {
+ /*
+ * TODO If there are messages for which a response is not required
+ * and failure to receive a reply is expected, this print is bogus.
+ */
EPRINTF("failed to receive ''%s'' message\n",
tapdisk_message_name(message->type));
return err;
}
- return 0;
+ if (tapdisk_message_is_rsp_paired(msg_type)) {
+ if (message->type - msg_type != 1) {
+ err = EINVAL;
+ EPRINTF("invalid response ''%s'' to message
''%s''\n",
+ tapdisk_message_name(message->type),
+ tapdisk_message_name(msg_type));
+ } else if (message->u.response.error) {
+ err = message->u.response.error;
+ EPRINTF("failed to serve message ''%s'': %s\n",
+ tapdisk_message_name(msg_type), strerror(err));
+ }
+ }
+
+ return err;
}
char *
@@ -161,7 +164,7 @@ tap_ctl_socket_name(int id)
char *name;
if (asprintf(&name, "%s/%s%d",
- BLKTAP2_CONTROL_DIR, BLKTAP2_CONTROL_SOCKET, id) == -1)
+ BLKTAP3_CONTROL_DIR, BLKTAP3_CONTROL_SOCKET, id) == -1)
return NULL;
return name;
@@ -222,7 +225,8 @@ tap_ctl_connect_id(int id, int *sfd)
}
int
-tap_ctl_connect_send_and_receive(int id, tapdisk_message_t *message, int
timeout)
+tap_ctl_connect_send_and_receive(int id, tapdisk_message_t * message,
+ struct timeval *timeout)
{
int err, sfd;
@@ -235,3 +239,20 @@ tap_ctl_connect_send_and_receive(int id,
close(sfd);
return err;
}
+
+int
+tap_ctl_read_message(int fd, tapdisk_message_t * message,
+ struct timeval *timeout)
+{
+ size_t size = sizeof(tapdisk_message_t);
+ int err;
+
+ err = tap_ctl_read_raw(fd, message, size, timeout);
+ if (err)
+ return err;
+
+ DBG("received ''%s'' message (uuid = %u)\n",
+ tapdisk_message_name(message->type), message->cookie);
+
+ return 0;
+}
Thanos Makatos
2013-Jan-24 12:20 UTC
[PATCH 8 of 9 RFC v3] blktap3/libblktapctl: Introduce tapdisk spawn functionality
This patch imports file control/tap-ctl-spawn.c from the existing blktap2
implementation, with most changes coming from blktap2 living in github.
Function tap-ctl-spawn is used for spawning a new tapdisk process in order to
serve a new virtual block device.
---
Changed since v2:
* Use "tapdisk3" instead of "tapdisk2" in getenv and
printf''s.
* Define tapdisk binary name and tapdisk binary location inside the source
file as it doesn''t need to be configurable.
diff --git a/tools/blktap2/control/tap-ctl-spawn.c
b/tools/blktap3/control/tap-ctl-spawn.c
copy from tools/blktap2/control/tap-ctl-spawn.c
copy to tools/blktap3/control/tap-ctl-spawn.c
--- a/tools/blktap2/control/tap-ctl-spawn.c
+++ b/tools/blktap3/control/tap-ctl-spawn.c
@@ -31,15 +31,20 @@
#include <unistd.h>
#include <stdlib.h>
#include <string.h>
+#include <signal.h>
#include <sys/wait.h>
#include "tap-ctl.h"
-#include "blktap2.h"
+#include "blktap3.h"
+#include "_paths.h"
+
+#define TAPDISK_EXEC "tapdisk"
+#define TAPDISK_EXECDIR LIBEXEC
static pid_t
__tap_ctl_spawn(int *readfd)
{
- int err, child, channel[2];
+ int child, channel[2];
char *tapdisk;
if (pipe(channel)) {
@@ -71,14 +76,21 @@ static pid_t
close(channel[0]);
close(channel[1]);
- tapdisk = getenv("TAPDISK2");
+ tapdisk = getenv("TAPDISK");
if (!tapdisk)
- tapdisk = "tapdisk2";
+ tapdisk = getenv("TAPDISK3"); /* FIXME */
- execlp(tapdisk, tapdisk, NULL);
+ if (tapdisk) {
+ execlp(tapdisk, tapdisk, NULL);
+ exit(errno);
+ }
- EPRINTF("exec failed\n");
- exit(1);
+ execl(TAPDISK_EXECDIR "/" TAPDISK_EXEC, TAPDISK_EXEC, NULL);
+
+ if (errno == ENOENT)
+ execl(TAPDISK_BUILDDIR "/" TAPDISK_EXEC, TAPDISK_EXEC, NULL);
+
+ exit(errno);
}
pid_t
@@ -90,7 +102,7 @@ tap_ctl_get_pid(const int id)
memset(&message, 0, sizeof(message));
message.type = TAPDISK_MESSAGE_PID;
- err = tap_ctl_connect_send_and_receive(id, &message, 2);
+ err = tap_ctl_connect_send_and_receive(id, &message, NULL);
if (err)
return err;
@@ -112,17 +124,23 @@ tap_ctl_wait(pid_t child)
if (WIFEXITED(status)) {
int code = WEXITSTATUS(status);
if (code)
- EPRINTF("tapdisk2[%d] failed, status %d\n", child, code);
+ EPRINTF("tapdisk3[%d] failed, status %d\n", child, code);
return -code;
}
if (WIFSIGNALED(status)) {
int signo = WTERMSIG(status);
- EPRINTF("tapdisk2[%d] killed by signal %d\n", child, signo);
+ EPRINTF("tapdisk3[%d] killed by signal %d\n", child, signo);
+ if (signo == SIGUSR1)
+ /* NB. there''s a race between tapdisk''s
+ * sigaction init and xen-bugtool shooting
+ * debug signals. If killed by something as
+ * innocuous as USR1, then retry. */
+ return -EAGAIN;
return -EINTR;
}
- EPRINTF("tapdisk2[%d]: unexpected status %#x\n", child, status);
+ EPRINTF("tapdisk3[%d]: unexpected status %#x\n", child, status);
return -EAGAIN;
}
@@ -139,8 +157,8 @@ tap_ctl_get_child_id(int readfd)
}
errno = 0;
- if (fscanf(f, BLKTAP2_CONTROL_DIR"/"
- BLKTAP2_CONTROL_SOCKET"%d", &id) != 1) {
+ if (fscanf(f, BLKTAP3_CONTROL_DIR "/"
+ BLKTAP3_CONTROL_SOCKET "%d", &id) != 1) {
errno = (errno ? : EINVAL);
EPRINTF("parsing id failed: %d\n", errno);
id = -1;
@@ -158,13 +176,17 @@ tap_ctl_spawn(void)
readfd = -1;
+ again:
child = __tap_ctl_spawn(&readfd);
if (child < 0)
return child;
err = tap_ctl_wait(child);
- if (err)
+ if (err) {
+ if (err == -EAGAIN)
+ goto again;
return err;
+ }
id = tap_ctl_get_child_id(readfd);
if (id < 0)
Thanos Makatos
2013-Jan-24 12:20 UTC
[PATCH 9 of 9 RFC v3] blktap3/libblktapctl: Introduce makefile that builds tapback-required libblktapctl functionality
This patch imports control/Makefile from the existing blktap2 implementation,
building only the libblktapctl functionality required by the tapback daemon.
The rest of the binaries/functionality will be introduced by a later patch.
Defines TAPDISK_EXEC, TAPDISK_EXECDIR, and TAPDISK_BUILDDIR are used by
tap-ctl-spawn, as it needs to know where the tapdisk binary is located in order
to spawn a tapdisk process.
---
Changed since v2:
* Ignore auto-generated file _paths.h.
* Remove TAPDISK_EXEC and TAPDISK_EXECDIR from the configuration system as
they don''t have to be configurable.
diff --git a/.hgignore b/.hgignore
--- a/.hgignore
+++ b/.hgignore
@@ -347,3 +347,4 @@
^unmodified_drivers/linux-2.6/.*\.ko$
^unmodified_drivers/linux-2.6/.*\.mod\.c$
^LibVNCServer.*
+^tools/blktap3/control/_paths.h$
diff --git a/tools/blktap2/control/Makefile b/tools/blktap3/control/Makefile
copy from tools/blktap2/control/Makefile
copy to tools/blktap3/control/Makefile
--- a/tools/blktap2/control/Makefile
+++ b/tools/blktap3/control/Makefile
@@ -6,40 +6,45 @@ MINOR = 0
LIBNAME = libblktapctl
LIBSONAME = $(LIBNAME).so.$(MAJOR)
-IBIN = tap-ctl
+genpath-target = $(call buildmakevars2file,_paths.h.tmp)
+$(eval $(genpath-target))
-CFLAGS += -Werror
-CFLAGS += -Wno-unused
-CFLAGS += -I../include -I../drivers
-CFLAGS += $(CFLAGS_xeninclude)
-CFLAGS += $(CFLAGS_libxenctrl)
-CFLAGS += -D_GNU_SOURCE
-CFLAGS += -DTAPCTL
+_paths.h: genpath
+ sed -e "s/\([^=]*\)=\(.*\)/#define \1 \2/g" $@.tmp >$@.2.tmp
+ rm -f $@.tmp
+ $(call move-if-changed,$@.2.tmp,$@)
-CTL_OBJS := tap-ctl-ipc.o
+override CFLAGS += \
+ -I../include \
+ -DTAPDISK_BUILDDIR=''"../drivers"'' \
+ $(CFLAGS_xeninclude) \
+ $(CFLAGS_libxenctrl) \
+ -D_GNU_SOURCE \
+ -DTAPCTL \
+ -Wall \
+ -Wextra \
+ -Werror
+
+# FIXME cause trouble
+override CFLAGS += \
+ -Wno-type-limits \
+ -Wno-missing-field-initializers \
+ -Wno-sign-compare
+
CTL_OBJS += tap-ctl-list.o
-CTL_OBJS += tap-ctl-allocate.o
-CTL_OBJS += tap-ctl-free.o
-CTL_OBJS += tap-ctl-create.o
-CTL_OBJS += tap-ctl-destroy.o
+CTL_OBJS += tap-ctl-info.o
+CTL_OBJS += tap-ctl-xen.o
+CTL_OBJS += tap-ctl-ipc.o
CTL_OBJS += tap-ctl-spawn.o
-CTL_OBJS += tap-ctl-attach.o
-CTL_OBJS += tap-ctl-detach.o
-CTL_OBJS += tap-ctl-open.o
-CTL_OBJS += tap-ctl-close.o
-CTL_OBJS += tap-ctl-pause.o
-CTL_OBJS += tap-ctl-unpause.o
-CTL_OBJS += tap-ctl-major.o
-CTL_OBJS += tap-ctl-check.o
+
+tap-ctl-spawn.o: _paths.h
CTL_PICS = $(patsubst %.o,%.opic,$(CTL_OBJS))
-OBJS = $(CTL_OBJS) tap-ctl.o
PICS = $(CTL_PICS)
LIB_STATIC = $(LIBNAME).a
LIB_SHARED = $(LIBSONAME).$(MINOR)
-IBIN = tap-ctl
all: build
@@ -51,27 +56,24 @@ build: $(IBIN) $(LIB_STATIC) $(LIB_SHARE
$(LIBSONAME): $(LIB_SHARED)
ln -sf $< $@
-tap-ctl: tap-ctl.o $(LIBNAME).so
- $(CC) $(LDFLAGS) -o $@ $^
-
$(LIB_STATIC): $(CTL_OBJS)
$(AR) r $@ $^
$(LIB_SHARED): $(CTL_PICS)
$(CC) $(LDFLAGS) -fPIC -Wl,$(SONAME_LDFLAG) -Wl,$(LIBSONAME) $(SHLIB_LDFLAGS)
-rdynamic $^ -o $@
-install: $(IBIN) $(LIB_STATIC) $(LIB_SHARED)
+install: $(LIB_STATIC) $(LIB_SHARED)
$(INSTALL_DIR) -p $(DESTDIR)$(SBINDIR)
- $(INSTALL_PROG) $(IBIN) $(DESTDIR)$(SBINDIR)
$(INSTALL_DATA) $(LIB_STATIC) $(DESTDIR)$(LIBDIR)
$(INSTALL_PROG) $(LIB_SHARED) $(DESTDIR)$(LIBDIR)
ln -sf $(LIBSONAME) $(DESTDIR)$(LIBDIR)/$(LIBNAME).so
ln -sf $(LIB_SHARED) $(DESTDIR)$(LIBDIR)/$(LIBSONAME)
clean:
- rm -f $(OBJS) $(PICS) $(DEPS) $(IBIN) $(LIB_STATIC) $(LIB_SHARED)
+ rm -f $(CTL_OBJS) $(PICS) $(DEPS) $(LIB_STATIC) $(LIB_SHARED)
rm -f $(LIBNAME).so $(LIBSONAME)
rm -f *~
+ rm -f _paths.h
.PHONY: all build clean install
Thanos Makatos
2013-Feb-25 11:15 UTC
Re: [PATCH 0 of 9 RFC v3] blktap3: Introduce a small subset of blktap3 files
Ping?> -----Original Message----- > From: Thanos Makatos [mailto:thanos.makatos@citrix.com] > Sent: 24 January 2013 12:21 > To: xen-devel@lists.xensource.com > Cc: Thanos Makatos > Subject: [PATCH 0 of 9 RFC v3] blktap3: Introduce a small subset of > blktap3 files > > blktap3 is a disk back-end driver. It is based on blktap2 but does not > require > the blktap/blkback kernel modules as it allows tapdisk to talk directly > to > blkfront. This primarily simplifies maintenance, and _may_ lead to > performance > improvements. blktap3 is based on a blktap2 fork maintained mostly by > Citrix > (it lives in github), so these changes are also imported, apart from > the > blktap3 ones. > > I''ve organised my upstream effort as follows: > 1. Upstream the smallest possible subset of blktap3 that will allow > guest VMs > to use RAW images backed by blktap3. This will enable early testing > on the > bits introduced by blktap3. > 2. Upstream the remaining of blktap3, most notably back-end drivers, > e.g. VHD > etc. > 3. Import bug fixes from blktap2 living in github. > 4. Import new features and optimisations from blktap2 living in github, > e.g. > the mirroring plug-in. > blktap3 is broken into patches that can be found here: > https://bitbucket.org/tmakatos/blktap3-patches > > blktap3 is made of the following components: > 1. blkfront (not a blktap3 component and already upstream): a virtual > block device driver in the guest VM that receives block I/O requests > and > forwards them to tapdisk via the shared ring. > 2. tapdisk: a user space process that receives block I/O requests from > blkfront, translates them to whatever the current backing file > format is > (i.e. RAW, VHD, qcow etc.), and performs the actual I/O. Apart from > block > I/O requests, the tapdisk also allows basic management of each > virtual > block device, e.g. a device may be temporarily paused. tapdisk > listens to > a loopback socket for such commands. The tap-ctl utility (explained > later) > can be used for managing the tapdisk. > 3. libsring (formerly known as libxenio): a user space library that > implements > the functionality required to access the shared ring. It is used by > tapdisk > to obtain the block I/O requests forwarded by the front-end, and to > produce > the corresponding responses. This is the very "heart" of blktap3, > it''s > architecture will be thoroughly explained by the patch series that > introduces it. > 4. tapback (formerly known as xenio): a user space daemon that acts as > the > back-end of each virtual block device: it monitors XenStore for the > block > front-end''s state changes, creates/destroys the shared ring, and > instructs > the tapdisk to connect to/disconnect from the shared ring. It also > communicates to the block front-end required parameters (e.g. block > device > size in sectors) via XenStore. The tapback daemon is only involved > during > the set up/tear down of the connection between the two ends, it does > not > participate in the data path. There is one tapback daemon per back- > end > driver domain, though we could have a tapback daemon per guest VM or > per > VBD. In this prototype, the tapdisk is spawned/destroyed by libxl > when a > domain is created/destroyed, in the exact same way as in blktap2 > (libxl > uses libblktapctl for this). When tapback detects a device creation > request > from a front-end, it must locate the tapdisk (previously created by > libxl) > designated to serve this VBD. There is no particular reason for this > design, > we could as well have the tapback daemon spawning the tapdisk (the > latter > choice looks neater IMO). Opting for the latter design wouldn''t > affect this > patch series that much. > 5. libblktapctl: a user space library where the tapdisk management > functions > are implemented, used by libxl and tap-ctl. > 6. tap-ctl: a user space utility that allows management of the tapdisk, > uses > libblktapctl. > > This patch series introduces a small subset of files required by > tapback (the > tapback daemon is introduced by the next patch series): > - basic blktap3 header files > - a rudimentary implementation of libblktapctl. Only the bits required > by > tapback to manage the tapdisk are introduced, the rest of this > library will > be introduced by later patches. > > --- > Changed since v1: > * In all patches the patch message has been improved. > * Patches 1, 5, and 6 use GPLv2. > * Patch 0: Basic explanation of blktap3''s fundamental components. > * Patch 9: Improved tools/blktap3/control/Makefile by moving hard coded > paths to config/StdGNU.mk. > > Changed since v2: > - Updated tapback daemon description.