# HG changeset patch
# User kfraser@xxxxxxxxxxxxxxxxxxxxx
# Date 1177583381 -3600
# Node ID 816d274e2a855bba83a0d052841a30fee78cbba3
# Parent 7f9ce06d3c61e9945b619dc79f35a79a265b3678
blktap: Segments can span multiple clusters with tap:qcow.
In blktap's qcow we need split up read/write requests if the requests
span multiple clusters. However, with our MAX_AIO_REQUESTS define we
assume that there is only ever a single aio request per tapdisk
request and under heavy i/o we can run out of room causing us to
cancel requests.
Dynamically allocate (based on cluster_bits) the various io request
queues the driver maintains.
Signed-off-by: Mark McLoughlin <markmc@xxxxxxxxxx>
---
tools/blktap/drivers/block-qcow.c | 67 ++++++++++++++++++++++++++++++--------
1 files changed, 53 insertions(+), 14 deletions(-)
diff -r 7f9ce06d3c61 -r 816d274e2a85 tools/blktap/drivers/block-qcow.c
--- a/tools/blktap/drivers/block-qcow.c Thu Apr 26 11:18:42 2007 +0100
+++ b/tools/blktap/drivers/block-qcow.c Thu Apr 26 11:29:41 2007 +0100
@@ -55,7 +55,6 @@
/******AIO DEFINES******/
#define REQUEST_ASYNC_FD 1
-#define MAX_AIO_REQS (MAX_REQUESTS * MAX_SEGMENTS_PER_REQ)
struct pending_aio {
td_callback_t cb;
@@ -146,18 +145,37 @@ struct tdqcow_state {
AES_KEY aes_encrypt_key; /*AES key*/
AES_KEY aes_decrypt_key; /*AES key*/
/* libaio state */
- io_context_t aio_ctx;
- struct iocb iocb_list [MAX_AIO_REQS];
- struct iocb *iocb_free [MAX_AIO_REQS];
- struct pending_aio pending_aio[MAX_AIO_REQS];
- int iocb_free_count;
- struct iocb *iocb_queue[MAX_AIO_REQS];
- int iocb_queued;
- int poll_fd; /* NB: we require aio_poll support */
- struct io_event aio_events[MAX_AIO_REQS];
+ io_context_t aio_ctx;
+ int max_aio_reqs;
+ struct iocb *iocb_list;
+ struct iocb **iocb_free;
+ struct pending_aio *pending_aio;
+ int iocb_free_count;
+ struct iocb **iocb_queue;
+ int iocb_queued;
+ int poll_fd; /* NB: we require aio_poll support */
+ struct io_event *aio_events;
};
static int decompress_cluster(struct tdqcow_state *s, uint64_t cluster_offset);
+
+static void free_aio_state(struct disk_driver *dd)
+{
+ struct tdqcow_state *s = (struct tdqcow_state *)dd->private;
+
+ if (s->sector_lock)
+ free(s->sector_lock);
+ if (s->iocb_list)
+ free(s->iocb_list);
+ if (s->pending_aio)
+ free(s->pending_aio);
+ if (s->aio_events)
+ free(s->aio_events);
+ if (s->iocb_free)
+ free(s->iocb_free);
+ if (s->iocb_queue)
+ free(s->iocb_queue);
+}
static int init_aio_state(struct disk_driver *dd)
{
@@ -166,6 +184,12 @@ static int init_aio_state(struct disk_dr
struct tdqcow_state *s = (struct tdqcow_state *)dd->private;
long ioidx;
+ s->iocb_list = NULL;
+ s->pending_aio = NULL;
+ s->aio_events = NULL;
+ s->iocb_free = NULL;
+ s->iocb_queue = NULL;
+
/*Initialize Locking bitmap*/
s->sector_lock = calloc(1, bs->size);
@@ -174,13 +198,26 @@ static int init_aio_state(struct disk_dr
goto fail;
}
+ /* A segment (i.e. a page) can span multiple clusters */
+ s->max_aio_reqs = (getpagesize() / s->cluster_size) + 1;
+
/* Initialize AIO */
- s->iocb_free_count = MAX_AIO_REQS;
+ s->iocb_free_count = s->max_aio_reqs;
s->iocb_queued = 0;
+
+ if (!(s->iocb_list = malloc(sizeof(struct iocb) * s->max_aio_reqs)) ||
+ !(s->pending_aio = malloc(sizeof(struct pending_aio) *
s->max_aio_reqs)) ||
+ !(s->aio_events = malloc(sizeof(struct io_event) *
s->max_aio_reqs)) ||
+ !(s->iocb_free = malloc(sizeof(struct iocb *) * s->max_aio_reqs))
||
+ !(s->iocb_queue = malloc(sizeof(struct iocb *) *
s->max_aio_reqs))) {
+ DPRINTF("Failed to allocate AIO structs (max_aio_reqs = %d)\n",
+ s->max_aio_reqs);
+ goto fail;
+ }
/*Signal kernel to create Poll FD for Asyc completion events*/
s->aio_ctx = (io_context_t) REQUEST_ASYNC_FD;
- s->poll_fd = io_setup(MAX_AIO_REQS, &s->aio_ctx);
+ s->poll_fd = io_setup(s->max_aio_reqs, &s->aio_ctx);
if (s->poll_fd < 0) {
if (s->poll_fd == -EAGAIN) {
@@ -198,7 +235,7 @@ static int init_aio_state(struct disk_dr
goto fail;
}
- for (i=0;i<MAX_AIO_REQS;i++)
+ for (i=0;i<s->max_aio_reqs;i++)
s->iocb_free[i] = &s->iocb_list[i];
DPRINTF("AIO state initialised\n");
@@ -946,6 +983,7 @@ int tdqcow_open (struct disk_driver *dd,
end_xenhdr:
if (init_aio_state(dd)!=0) {
DPRINTF("Unable to initialise AIO state\n");
+ free_aio_state(dd);
goto fail;
}
init_fds(dd);
@@ -962,6 +1000,7 @@ int tdqcow_open (struct disk_driver *dd,
fail:
DPRINTF("QCOW Open failed\n");
+ free_aio_state(dd);
free(s->l1_table);
free(s->l2_cache);
free(s->cluster_cache);
@@ -1145,7 +1184,7 @@ int tdqcow_do_callbacks(struct disk_driv
if (sid > MAX_IOFD) return 1;
/* Non-blocking test for completed io. */
- ret = io_getevents(prv->aio_ctx, 0, MAX_AIO_REQS, prv->aio_events,
+ ret = io_getevents(prv->aio_ctx, 0, prv->max_aio_reqs, prv->aio_events,
NULL);
for (ep = prv->aio_events, i = ret; i-- > 0; ep++) {
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