[Libguestfs] [PATCH nbdkit 2/2] vddk: Relax thread model to PARALLEL and implement a disk handle pool.
Richard W.M. Jones
rjones at redhat.com
Thu Aug 6 13:16:11 UTC 2020
The pool is only used for readonly connections, since writable
connections usually take a lock on the server side and therefore you
cannot open more than one.
---
plugins/vddk/nbdkit-vddk-plugin.pod | 7 +
plugins/vddk/vddk.c | 201 ++++++++++++++++++++++------
2 files changed, 164 insertions(+), 44 deletions(-)
diff --git a/plugins/vddk/nbdkit-vddk-plugin.pod b/plugins/vddk/nbdkit-vddk-plugin.pod
index e5539da9..288aed4b 100644
--- a/plugins/vddk/nbdkit-vddk-plugin.pod
+++ b/plugins/vddk/nbdkit-vddk-plugin.pod
@@ -175,6 +175,13 @@ Read the password from file descriptor number C<FD>, inherited from
the parent process when nbdkit starts up. This is also a secure
method to supply a password.
+=item B<pool-max=>N
+
+To improve performance, for read-only connections (see I<-r> option)
+the plugin will open a pool of VixDiskLibHandle disk handles. You can
+use this option to control the maximum size of the pool. The default
+is 8. To disable this feature, set it to 0 or 1.
+
=item B<port=>PORT
The port on the VCenter/ESXi host. Defaults to 443.
diff --git a/plugins/vddk/vddk.c b/plugins/vddk/vddk.c
index 5926e181..173d5031 100644
--- a/plugins/vddk/vddk.c
+++ b/plugins/vddk/vddk.c
@@ -52,6 +52,7 @@
#include "isaligned.h"
#include "minmax.h"
#include "rounding.h"
+#include "vector.h"
#include "vddk.h"
#include "vddk-structs.h"
@@ -85,6 +86,7 @@ char *libdir; /* libdir */
static uint16_t nfc_host_port; /* nfchostport */
char *password; /* password */
static uint16_t port; /* port */
+static unsigned pool_max = 8; /* pool-max */
static const char *server_name; /* server */
static bool single_link; /* single-link */
static const char *snapshot_moref; /* snapshot */
@@ -233,6 +235,12 @@ vddk_config (const char *key, const char *value)
if (nbdkit_parse_uint16_t ("port", value, &port) == -1)
return -1;
}
+ else if (strcmp (key, "pool-max") == 0) {
+ if (nbdkit_parse_unsigned ("pool-max", value, &pool_max) == -1)
+ return -1;
+ if (pool_max < 1)
+ pool_max = 1;
+ }
else if (strcmp (key, "reexeced_") == 0) {
/* Special name because it is only for internal use. */
reexeced = (char *)value;
@@ -482,20 +490,37 @@ vddk_dump_plugin (void)
* https://code.vmware.com/docs/11750/virtual-disk-development-kit-programming-guide/GUID-6BE903E8-DC70-46D9-98E4-E34A2002C2AD.html
*
* Before nbdkit 1.22 we used SERIALIZE_ALL_REQUESTS. Since nbdkit
- * 1.22 we changed this to SERIALIZE_REQUESTS and added a mutex around
- * calls to VixDiskLib_Open and VixDiskLib_Close. This is not quite
- * within the letter of the rules, but is within the spirit.
+ * 1.22 we changed this to PARALLEL, added a mutex around calls to
+ * VixDiskLib_Open and VixDiskLib_Close, and use a pool of disk
+ * handles. This is not quite within the letter of the rules, but is
+ * within the spirit.
*/
-#define THREAD_MODEL NBDKIT_THREAD_MODEL_SERIALIZE_REQUESTS
+#define THREAD_MODEL NBDKIT_THREAD_MODEL_PARALLEL
/* Lock protecting open/close calls - see above. */
static pthread_mutex_t open_close_lock = PTHREAD_MUTEX_INITIALIZER;
-/* The per-connection handle. */
+struct handle;
struct vddk_handle {
+ VixDiskLibHandle vddk_handle;
+ bool in_use;
+ struct handle *h;
+};
+DEFINE_VECTOR_TYPE(vddk_handles, struct vddk_handle)
+
+/* The per-connection handle. */
+struct handle {
VixDiskLibConnectParams *params; /* connection parameters */
VixDiskLibConnection connection; /* connection */
- VixDiskLibHandle handle; /* disk handle */
+ int readonly; /* readonly flag for this connection */
+ uint32_t flags; /* open flags */
+
+ /* Pool of VDDK disk handles. Do not access this directly, use
+ * GET_VDDK_HANDLE_FOR_CURRENT_SCOPE macro to get a free handle.
+ */
+ pthread_mutex_t vddk_handles_lock;
+ pthread_cond_t vddk_handles_cond;
+ vddk_handles vddk_handles;
};
static inline VixDiskLibConnectParams *
@@ -531,17 +556,28 @@ free_connect_params (VixDiskLibConnectParams *params)
static void *
vddk_open (int readonly)
{
- ACQUIRE_LOCK_FOR_CURRENT_SCOPE (&open_close_lock);
- struct vddk_handle *h;
+ struct handle *h;
VixError err;
- uint32_t flags;
- h = malloc (sizeof *h);
+ h = calloc (1, sizeof *h);
if (h == NULL) {
- nbdkit_error ("malloc: %m");
+ nbdkit_error ("calloc: %m");
return NULL;
}
+ h->readonly = readonly;
+ pthread_mutex_init (&h->vddk_handles_lock, NULL);
+ pthread_cond_init (&h->vddk_handles_cond, NULL);
+
+ /* We have to reserve this vector to ensure that it is not
+ * reallocated, as that would make the pointer returned by
+ * get_vddk_handle in another thread invalid.
+ */
+ if (vddk_handles_reserve (&h->vddk_handles, pool_max) == -1) {
+ nbdkit_error ("realloc: %m");
+ goto err0;
+ }
+
h->params = allocate_connect_params ();
if (h->params == NULL) {
nbdkit_error ("allocate VixDiskLibConnectParams: %m");
@@ -589,49 +625,120 @@ vddk_open (int readonly)
goto err1;
}
- flags = 0;
+ h->flags = 0;
if (readonly)
- flags |= VIXDISKLIB_FLAG_OPEN_READ_ONLY;
+ h->flags |= VIXDISKLIB_FLAG_OPEN_READ_ONLY;
if (single_link)
- flags |= VIXDISKLIB_FLAG_OPEN_SINGLE_LINK;
+ h->flags |= VIXDISKLIB_FLAG_OPEN_SINGLE_LINK;
if (unbuffered)
- flags |= VIXDISKLIB_FLAG_OPEN_UNBUFFERED;
-
- DEBUG_CALL ("VixDiskLib_Open",
- "connection, %s, %d, &handle", filename, flags);
- err = VixDiskLib_Open (h->connection, filename, flags, &h->handle);
- if (err != VIX_OK) {
- VDDK_ERROR (err, "VixDiskLib_Open: %s", filename);
- goto err2;
- }
-
- nbdkit_debug ("transport mode: %s",
- VixDiskLib_GetTransportMode (h->handle));
+ h->flags |= VIXDISKLIB_FLAG_OPEN_UNBUFFERED;
return h;
- err2:
- DEBUG_CALL ("VixDiskLib_Disconnect", "connection");
- VixDiskLib_Disconnect (h->connection);
err1:
free_connect_params (h->params);
err0:
+ free (h->vddk_handles.ptr);
+ pthread_cond_destroy (&h->vddk_handles_cond);
+ pthread_mutex_destroy (&h->vddk_handles_lock);
free (h);
return NULL;
}
+/* Get a VDDK handle on demand. */
+static VixDiskLibHandle
+open_vddk_handle (struct handle *h)
+{
+ ACQUIRE_LOCK_FOR_CURRENT_SCOPE (&open_close_lock);
+ VixDiskLibHandle vddk_handle;
+ VixError err;
+
+ DEBUG_CALL ("VixDiskLib_Open",
+ "connection, %s, %d, &handle", filename, h->flags);
+ err = VixDiskLib_Open (h->connection, filename, h->flags, &vddk_handle);
+ if (err != VIX_OK) {
+ VDDK_ERROR (err, "VixDiskLib_Open: %s", filename);
+ return NULL;
+ }
+
+ nbdkit_debug ("transport mode: %s",
+ VixDiskLib_GetTransportMode (vddk_handle));
+ return vddk_handle;
+}
+
+static struct vddk_handle *
+get_vddk_handle (struct handle *h)
+{
+ const unsigned max = h->readonly ? pool_max : 1;
+ ACQUIRE_LOCK_FOR_CURRENT_SCOPE (&h->vddk_handles_lock);
+ VixDiskLibHandle vddk_handle;
+ size_t i;
+
+ again:
+ /* See if there's a handle in the pool which is not in use. */
+ for (i = 0; i < h->vddk_handles.size; ++i) {
+ if (!h->vddk_handles.ptr[i].in_use) {
+ h->vddk_handles.ptr[i].in_use = true;
+ return &h->vddk_handles.ptr[i];
+ }
+ }
+
+ /* If the pool is too big we have to wait for another thread to
+ * finish using its handle and try again.
+ */
+ if (h->vddk_handles.size >= max) {
+ pthread_cond_wait (&h->vddk_handles_cond, &h->vddk_handles_lock);
+ goto again;
+ }
+
+ /* Open another handle and add it to the pool. Note that
+ * vddk_handles_append cannot fail because we reserved space in
+ * vddk_open.
+ */
+ vddk_handle = open_vddk_handle (h);
+ if (vddk_handle == NULL)
+ return NULL;
+ vddk_handles_append (&h->vddk_handles,
+ (struct vddk_handle){ vddk_handle, true, h });
+ return &h->vddk_handles.ptr[h->vddk_handles.size-1];
+}
+
+static void
+put_vddk_handle (struct vddk_handle **p)
+{
+ if (*p) {
+ ACQUIRE_LOCK_FOR_CURRENT_SCOPE (&(*p)->h->vddk_handles_lock);
+ assert ((*p)->in_use);
+ (*p)->in_use = false;
+ pthread_cond_signal (&(*p)->h->vddk_handles_cond);
+ }
+}
+
+/* Wrap get/put_vddk_handle in nicer macro. */
+#define GET_VDDK_HANDLE_FOR_CURRENT_SCOPE(h, name) \
+ __attribute__((cleanup (put_vddk_handle))) \
+ struct vddk_handle *name##_h = get_vddk_handle (h); \
+ if (name##_h == NULL) return -1; \
+ VixDiskLibHandle name = name##_h->vddk_handle
+
/* Free up the per-connection handle. */
static void
vddk_close (void *handle)
{
ACQUIRE_LOCK_FOR_CURRENT_SCOPE (&open_close_lock);
- struct vddk_handle *h = handle;
+ struct handle *h = handle;
+ size_t i;
- DEBUG_CALL ("VixDiskLib_Close", "handle");
- VixDiskLib_Close (h->handle);
+ for (i = 0; i < h->vddk_handles.size; ++i) {
+ DEBUG_CALL ("VixDiskLib_Close", "handle");
+ VixDiskLib_Close (h->vddk_handles.ptr[i].vddk_handle);
+ }
+ free (h->vddk_handles.ptr);
DEBUG_CALL ("VixDiskLib_Disconnect", "connection");
VixDiskLib_Disconnect (h->connection);
free_connect_params (h->params);
+ pthread_cond_destroy (&h->vddk_handles_cond);
+ pthread_mutex_destroy (&h->vddk_handles_lock);
free (h);
}
@@ -639,13 +746,14 @@ vddk_close (void *handle)
static int64_t
vddk_get_size (void *handle)
{
- struct vddk_handle *h = handle;
+ struct handle *h = handle;
+ GET_VDDK_HANDLE_FOR_CURRENT_SCOPE (h, vddk_handle);
VixDiskLibInfo *info;
VixError err;
uint64_t size;
DEBUG_CALL ("VixDiskLib_GetInfo", "handle, &info");
- err = VixDiskLib_GetInfo (h->handle, &info);
+ err = VixDiskLib_GetInfo (vddk_handle, &info);
if (err != VIX_OK) {
VDDK_ERROR (err, "VixDiskLib_GetInfo");
return -1;
@@ -687,7 +795,8 @@ static int
vddk_pread (void *handle, void *buf, uint32_t count, uint64_t offset,
uint32_t flags)
{
- struct vddk_handle *h = handle;
+ struct handle *h = handle;
+ GET_VDDK_HANDLE_FOR_CURRENT_SCOPE (h, vddk_handle);
VixError err;
/* Align to sectors. */
@@ -706,7 +815,7 @@ vddk_pread (void *handle, void *buf, uint32_t count, uint64_t offset,
"handle, %" PRIu64 " sectors, "
"%" PRIu32 " sectors, buffer",
offset, count);
- err = VixDiskLib_Read (h->handle, offset, count, buf);
+ err = VixDiskLib_Read (vddk_handle, offset, count, buf);
if (err != VIX_OK) {
VDDK_ERROR (err, "VixDiskLib_Read");
return -1;
@@ -726,7 +835,8 @@ vddk_pwrite (void *handle, const void *buf, uint32_t count, uint64_t offset,
uint32_t flags)
{
const bool fua = flags & NBDKIT_FLAG_FUA;
- struct vddk_handle *h = handle;
+ struct handle *h = handle;
+ GET_VDDK_HANDLE_FOR_CURRENT_SCOPE (h, vddk_handle);
VixError err;
/* Align to sectors. */
@@ -745,7 +855,7 @@ vddk_pwrite (void *handle, const void *buf, uint32_t count, uint64_t offset,
"handle, %" PRIu64 " sectors, "
"%" PRIu32 " sectors, buffer",
offset, count);
- err = VixDiskLib_Write (h->handle, offset, count, buf);
+ err = VixDiskLib_Write (vddk_handle, offset, count, buf);
if (err != VIX_OK) {
VDDK_ERROR (err, "VixDiskLib_Write");
return -1;
@@ -761,7 +871,8 @@ vddk_pwrite (void *handle, const void *buf, uint32_t count, uint64_t offset,
static int
vddk_flush (void *handle, uint32_t flags)
{
- struct vddk_handle *h = handle;
+ struct handle *h = handle;
+ GET_VDDK_HANDLE_FOR_CURRENT_SCOPE (h, vddk_handle);
VixError err;
/* The Flush call was not available in VDDK < 6.0 so this is simply
@@ -771,7 +882,7 @@ vddk_flush (void *handle, uint32_t flags)
return 0;
DEBUG_CALL ("VixDiskLib_Flush", "handle");
- err = VixDiskLib_Flush (h->handle);
+ err = VixDiskLib_Flush (vddk_handle);
if (err != VIX_OK) {
VDDK_ERROR (err, "VixDiskLib_Flush");
return -1;
@@ -783,7 +894,8 @@ vddk_flush (void *handle, uint32_t flags)
static int
vddk_can_extents (void *handle)
{
- struct vddk_handle *h = handle;
+ struct handle *h = handle;
+ GET_VDDK_HANDLE_FOR_CURRENT_SCOPE (h, vddk_handle);
VixError err;
VixDiskLibBlockList *block_list;
@@ -808,7 +920,7 @@ vddk_can_extents (void *handle)
DEBUG_CALL ("VixDiskLib_QueryAllocatedBlocks",
"handle, 0, %d sectors, %d sectors",
VIXDISKLIB_MIN_CHUNK_SIZE, VIXDISKLIB_MIN_CHUNK_SIZE);
- err = VixDiskLib_QueryAllocatedBlocks (h->handle,
+ err = VixDiskLib_QueryAllocatedBlocks (vddk_handle,
0, VIXDISKLIB_MIN_CHUNK_SIZE,
VIXDISKLIB_MIN_CHUNK_SIZE,
&block_list);
@@ -864,7 +976,8 @@ static int
vddk_extents (void *handle, uint32_t count, uint64_t offset, uint32_t flags,
struct nbdkit_extents *extents)
{
- struct vddk_handle *h = handle;
+ struct handle *h = handle;
+ GET_VDDK_HANDLE_FOR_CURRENT_SCOPE (h, vddk_handle);
bool req_one = flags & NBDKIT_FLAG_REQ_ONE;
uint64_t position, end, start_sector;
@@ -896,7 +1009,7 @@ vddk_extents (void *handle, uint32_t count, uint64_t offset, uint32_t flags,
"handle, %" PRIu64 " sectors, %" PRIu64 " sectors, "
"%d sectors",
start_sector, nr_sectors, VIXDISKLIB_MIN_CHUNK_SIZE);
- err = VixDiskLib_QueryAllocatedBlocks (h->handle,
+ err = VixDiskLib_QueryAllocatedBlocks (vddk_handle,
start_sector, nr_sectors,
VIXDISKLIB_MIN_CHUNK_SIZE,
&block_list);
--
2.27.0
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