this patch introduces a new ioctl that prevents requests being aborted on a socket error
and instead the request is retried on the next connection
or is cleaned up on timeout, disconnect or clear_sock.
Signed-off-by: Tim Dawson <tim.dawson@xxxxxxxxxx>
---
drivers/block/nbd.c | 80 +++++++++++++++++++++++++++++++++++++++---------
include/uapi/linux/nbd.h | 1 +
2 files changed, 66 insertions(+), 15 deletions(-)
diff --git a/drivers/block/nbd.c b/drivers/block/nbd.c
index ba405b5..727f5b5 100644
--- a/drivers/block/nbd.c
+++ b/drivers/block/nbd.c
@@ -43,6 +43,7 @@
#define NBD_TIMEDOUT 0
#define NBD_DISCONNECT_REQUESTED 1
+#define NBD_RESEND_DO_IT 2
struct nbd_device {
u32 flags;
@@ -433,8 +434,6 @@ static int nbd_thread_recv(struct nbd_device *nbd, struct block_device *bdev)
return ret;
}
- nbd_size_update(nbd, bdev);
-
while (1) {
cmd = nbd_read_stat(nbd);
if (IS_ERR(cmd)) {
@@ -442,10 +441,19 @@ static int nbd_thread_recv(struct nbd_device *nbd, struct block_device *bdev)
break;
}
+ struct request *req = blk_mq_rq_from_pdu(cmd);
+
+ if (test_bit(NBD_RESEND_DO_IT, &nbd->runtime_flags) && req->errors) {
+ /* reset errors - we will reconnect and fix these */
+ req->errors = 0;
+ ret = -EIO;
+ dev_warn(disk_to_dev(nbd->disk), "Handling failed recv %p\n", req);
+ break;
+ }
+
nbd_end_request(cmd);
- }
- nbd_size_clear(nbd, bdev);
+ }
device_remove_file(disk_to_dev(nbd->disk), &pid_attr);
return ret;
@@ -503,7 +511,10 @@ static void nbd_handle_cmd(struct nbd_cmd *cmd)
goto error_out;
}
- if (nbd_send_cmd(nbd, cmd) != 0) {
+ /* if not NBD_RESEND_DO_IT and there is an error,
+ * we dont want to nbd_end_request if we can retry later
+ */
+ if (nbd_send_cmd(nbd, cmd) != 0 && !test_bit(NBD_RESEND_DO_IT, &nbd->runtime_flags)) {
dev_err(disk_to_dev(nbd->disk), "Request send failed\n");
req->errors++;
nbd_end_request(cmd);
@@ -515,8 +526,32 @@ static void nbd_handle_cmd(struct nbd_cmd *cmd)
return;
error_out:
- req->errors++;
- nbd_end_request(cmd);
+ if (test_bit(NBD_RESEND_DO_IT, &nbd->runtime_flags)) {
+ nbd->task_send = NULL;
+ mutex_unlock(&nbd->tx_lock);
+ return;
+ }
+
+ req->errors++;
+ nbd_end_request(cmd);
+}
+
+
+static void nbd_resend_req(struct request *req, void *data, bool reserved)
+{
+ struct nbd_device *nbd = data;
+ struct nbd_cmd *cmd = blk_mq_rq_to_pdu(req);
+
+ dev_err(nbd_to_dev(nbd), "resend request %p\n", cmd);
+ nbd_handle_cmd(cmd);
+}
+
+static void nbd_resend_pending(struct nbd_device *nbd)
+{
+ BUG_ON(nbd->magic != NBD_MAGIC);
+
+ blk_mq_tagset_busy_iter(&nbd->tag_set, nbd_resend_req, nbd);
+ dev_dbg(disk_to_dev(nbd->disk), "queue cleared\n");
}
static int nbd_queue_rq(struct blk_mq_hw_ctx *hctx,
@@ -661,6 +696,10 @@ static int __nbd_ioctl(struct block_device *bdev, struct nbd_device *nbd,
nbd->flags = arg;
return 0;
+ case NBD_SET_RESEND:
+ set_bit(NBD_RESEND_DO_IT, &nbd->runtime_flags);
+ return 0;
+
case NBD_DO_IT: {
int error;
@@ -675,26 +714,37 @@ static int __nbd_ioctl(struct block_device *bdev, struct nbd_device *nbd,
nbd_parse_flags(nbd, bdev);
+ /* Resend remaining commands from last connection */
+ if (test_bit(NBD_RESEND_DO_IT, &nbd->runtime_flags))
+ nbd_resend_pending(nbd);
+
+ nbd_size_update(nbd, bdev);
+
nbd_dev_dbg_init(nbd);
- error = nbd_thread_recv(nbd, bdev);
+ error = nbd_thread_recv(nbd, bdev); //blocking
nbd_dev_dbg_close(nbd);
mutex_lock(&nbd->tx_lock);
nbd->task_recv = NULL;
sock_shutdown(nbd);
- nbd_clear_que(nbd);
- kill_bdev(bdev);
- nbd_bdev_reset(bdev);
+ if (!test_bit(NBD_RESEND_DO_IT, &nbd->runtime_flags) ||
+ test_bit(NBD_DISCONNECT_REQUESTED, &nbd->runtime_flags)) {
- /* user requested, ignore socket errors */
- if (test_bit(NBD_DISCONNECT_REQUESTED, &nbd->runtime_flags))
+ dev_info(disk_to_dev(nbd->disk), "NBD_DO_IT cleanup\n");
+ nbd_size_clear(nbd, bdev);
+ nbd_clear_que(nbd);
+ kill_bdev(bdev);
+ nbd_bdev_reset(bdev);
+ nbd_reset(nbd);
+
+ /* user requested, ignore socket errors */
error = 0;
+ }
+
if (test_bit(NBD_TIMEDOUT, &nbd->runtime_flags))
error = -ETIMEDOUT;
- nbd_reset(nbd);
-
return error;
}
diff --git a/include/uapi/linux/nbd.h b/include/uapi/linux/nbd.h
index e08e413..9031c87 100644
--- a/include/uapi/linux/nbd.h
+++ b/include/uapi/linux/nbd.h
@@ -28,6 +28,7 @@
#define NBD_DISCONNECT _IO( 0xab, 8 )
#define NBD_SET_TIMEOUT _IO( 0xab, 9 )
#define NBD_SET_FLAGS _IO( 0xab, 10)
+#define NBD_SET_RESEND _IO( 0xab, 11)
enum {
NBD_CMD_READ = 0,
--
1.9.1
--
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