AcoSail/kernel_optimize_test
8
0
Fork 0
forked from luck/tmp_suning_uos_patched
Code Pull Requests Activity

nbd: handle unexpected replies better

Browse Source 
If the server or network is misbehaving and we get an unexpected reply
we can sometimes miss the request not being started and wait on a
request and never get a response, or even double complete the same
request.  Fix this by replacing the send_complete completion with just a
per command lock.  Add a per command cookie as well so that we can know
if we're getting a double completion for a previous event.  Also check
to make sure we dont have REQUEUED set as that means we raced with the
timeout handler and need to just let the retry occur.

Signed-off-by: Josef Bacik <josef@toxicpanda.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
This commit is contained in:
Josef Bacik 2018-07-16 12:11:35 -04:00 committed by Jens Axboe
parent d7d94d48a2
commit 8f3ea35929
1 changed files with 61 additions and 14 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

75
drivers/block/nbd.c
View File

@ -116,11 +116,12 @@ struct nbd_device {
struct nbd_cmd {
struct nbd_device *nbd;
struct mutex lock;
int index;
int cookie;
struct completion send_complete;
blk_status_t status;
unsigned long flags;
u32 cmd_cookie;
};
#if IS_ENABLED(CONFIG_DEBUG_FS)
@ -157,6 +158,27 @@ static void nbd_requeue_cmd(struct nbd_cmd *cmd)
blk_mq_requeue_request(req, true);
}
#define NBD_COOKIE_BITS 32
static u64 nbd_cmd_handle(struct nbd_cmd *cmd)
{
struct request *req = blk_mq_rq_from_pdu(cmd);
u32 tag = blk_mq_unique_tag(req);
u64 cookie = cmd->cmd_cookie;
return (cookie << NBD_COOKIE_BITS) | tag;
}
static u32 nbd_handle_to_tag(u64 handle)
{
return (u32)handle;
}
static u32 nbd_handle_to_cookie(u64 handle)
{
return (u32)(handle >> NBD_COOKIE_BITS);
}
static const char *nbdcmd_to_ascii(int cmd)
{
switch (cmd) {
@ -330,6 +352,9 @@ static enum blk_eh_timer_return nbd_xmit_timeout(struct request *req,
}
config = nbd->config;
if (!mutex_trylock(&cmd->lock))
return BLK_EH_RESET_TIMER;
if (config->num_connections > 1) {
dev_err_ratelimited(nbd_to_dev(nbd),
"Connection timed out, retrying (%d/%d alive)\n",
@ -354,6 +379,7 @@ static enum blk_eh_timer_return nbd_xmit_timeout(struct request *req,
nbd_mark_nsock_dead(nbd, nsock, 1);
mutex_unlock(&nsock->tx_lock);
}
mutex_unlock(&cmd->lock);
nbd_requeue_cmd(cmd);
nbd_config_put(nbd);
return BLK_EH_DONE;
@ -364,6 +390,7 @@ static enum blk_eh_timer_return nbd_xmit_timeout(struct request *req,
}
set_bit(NBD_TIMEDOUT, &config->runtime_flags);
cmd->status = BLK_STS_IOERR;
mutex_unlock(&cmd->lock);
sock_shutdown(nbd);
nbd_config_put(nbd);
done:
@ -441,9 +468,9 @@ static int nbd_send_cmd(struct nbd_device *nbd, struct nbd_cmd *cmd, int index)
struct iov_iter from;
unsigned long size = blk_rq_bytes(req);
struct bio *bio;
u64 handle;
u32 type;
u32 nbd_cmd_flags = 0;
u32 tag = blk_mq_unique_tag(req);
int sent = nsock->sent, skip = 0;
iov_iter_kvec(&from, WRITE | ITER_KVEC, &iov, 1, sizeof(request));
@ -485,6 +512,8 @@ static int nbd_send_cmd(struct nbd_device *nbd, struct nbd_cmd *cmd, int index)
goto send_pages;
}
iov_iter_advance(&from, sent);
} else {
cmd->cmd_cookie++;
}
cmd->index = index;
cmd->cookie = nsock->cookie;
@ -493,7 +522,8 @@ static int nbd_send_cmd(struct nbd_device *nbd, struct nbd_cmd *cmd, int index)
request.from = cpu_to_be64((u64)blk_rq_pos(req) << 9);
request.len = htonl(size);
}
memcpy(request.handle, &tag, sizeof(tag));
handle = nbd_cmd_handle(cmd);
memcpy(request.handle, &handle, sizeof(handle));
dev_dbg(nbd_to_dev(nbd), "request %p: sending control (%s@%llu,%uB)\n",
req, nbdcmd_to_ascii(type),
@ -586,10 +616,12 @@ static struct nbd_cmd *nbd_read_stat(struct nbd_device *nbd, int index)
struct nbd_reply reply;
struct nbd_cmd *cmd;
struct request *req = NULL;
u64 handle;
u16 hwq;
u32 tag;
struct kvec iov = {.iov_base = &reply, .iov_len = sizeof(reply)};
struct iov_iter to;
int ret = 0;
reply.magic = 0;
iov_iter_kvec(&to, READ | ITER_KVEC, &iov, 1, sizeof(reply));
@ -607,8 +639,8 @@ static struct nbd_cmd *nbd_read_stat(struct nbd_device *nbd, int index)
return ERR_PTR(-EPROTO);
}
memcpy(&tag, reply.handle, sizeof(u32));
memcpy(&handle, reply.handle, sizeof(handle));
tag = nbd_handle_to_tag(handle);
hwq = blk_mq_unique_tag_to_hwq(tag);
if (hwq < nbd->tag_set.nr_hw_queues)
req = blk_mq_tag_to_rq(nbd->tag_set.tags[hwq],
@ -619,11 +651,25 @@ static struct nbd_cmd *nbd_read_stat(struct nbd_device *nbd, int index)
return ERR_PTR(-ENOENT);
}
cmd = blk_mq_rq_to_pdu(req);
mutex_lock(&cmd->lock);
if (cmd->cmd_cookie != nbd_handle_to_cookie(handle)) {
dev_err(disk_to_dev(nbd->disk), "Double reply on req %p, cmd_cookie %u, handle cookie %u\n",
req, cmd->cmd_cookie, nbd_handle_to_cookie(handle));
ret = -ENOENT;
goto out;
}
if (test_bit(NBD_CMD_REQUEUED, &cmd->flags)) {
dev_err(disk_to_dev(nbd->disk), "Raced with timeout on req %p\n",
req);
ret = -ENOENT;
goto out;
}
if (ntohl(reply.error)) {
dev_err(disk_to_dev(nbd->disk), "Other side returned error (%d)\n",
ntohl(reply.error));
cmd->status = BLK_STS_IOERR;
return cmd;
goto out;
}
dev_dbg(nbd_to_dev(nbd), "request %p: got reply\n", req);
@ -648,18 +694,18 @@ static struct nbd_cmd *nbd_read_stat(struct nbd_device *nbd, int index)
if (nbd_disconnected(config) ||
config->num_connections <= 1) {
cmd->status = BLK_STS_IOERR;
return cmd;
goto out;
}
return ERR_PTR(-EIO);
ret = -EIO;
goto out;
}
dev_dbg(nbd_to_dev(nbd), "request %p: got %d bytes data\n",
req, bvec.bv_len);
}
} else {
/* See the comment in nbd_queue_rq. */
wait_for_completion(&cmd->send_complete);
}
return cmd;
out:
mutex_unlock(&cmd->lock);
return ret ? ERR_PTR(ret) : cmd;
}
static void recv_work(struct work_struct *work)
@ -855,7 +901,7 @@ static blk_status_t nbd_queue_rq(struct blk_mq_hw_ctx *hctx,
* that the server is misbehaving (or there was an error) before we're
* done sending everything over the wire.
*/
init_completion(&cmd->send_complete);
mutex_lock(&cmd->lock);
clear_bit(NBD_CMD_REQUEUED, &cmd->flags);
/* We can be called directly from the user space process, which means we
@ -868,7 +914,7 @@ static blk_status_t nbd_queue_rq(struct blk_mq_hw_ctx *hctx,
ret = BLK_STS_IOERR;
else if (!ret)
ret = BLK_STS_OK;
complete(&cmd->send_complete);
mutex_unlock(&cmd->lock);
return ret;
}
@ -1475,6 +1521,7 @@ static int nbd_init_request(struct blk_mq_tag_set *set, struct request *rq,
struct nbd_cmd *cmd = blk_mq_rq_to_pdu(rq);
cmd->nbd = set->driver_data;
cmd->flags = 0;
mutex_init(&cmd->lock);
return 0;
}