Message ID | 20240529213426.3165433-1-bvanassche@acm.org (mailing list archive) |
---|---|
State | New, archived |
Headers | show |
Series | nbd: Remove __force casts | expand |
On Wed, May 29, 2024 at 02:34:26PM -0700, Bart Van Assche wrote: > Make it again possible for sparse to verify that blk_status_t and Unix > error codes are used in the proper context by making nbd_send_cmd() > return a struct instead of an integer. > > Additionally, move a misplaced comment to where it should occur. > > No functionality has been changed. Structures larger than a register lead to horrible code generation with most ABIs. It's also really hard to follow when all that is needed is to move the flag setting and requeueing into nbd_send_cmd where it kinda belongs anyway: diff --git a/drivers/block/nbd.c b/drivers/block/nbd.c index ad887d614d5b3f..3fb3359850e21f 100644 --- a/drivers/block/nbd.c +++ b/drivers/block/nbd.c @@ -589,10 +589,10 @@ static inline int was_interrupted(int result) } /* - * Returns BLK_STS_RESOURCE if the caller should retry after a delay. Returns - * -EAGAIN if the caller should requeue @cmd. Returns -EIO if sending failed. + * Returns BLK_STS_RESOURCE if the caller should retry after a delay. + * Returns BLK_STS_IOERR if sending failed. */ -static int nbd_send_cmd(struct nbd_device *nbd, struct nbd_cmd *cmd, int index) +static blk_status_t nbd_send_cmd(struct nbd_device *nbd, struct nbd_cmd *cmd, int index) { struct request *req = blk_mq_rq_from_pdu(cmd); struct nbd_config *config = nbd->config; @@ -614,13 +614,13 @@ static int nbd_send_cmd(struct nbd_device *nbd, struct nbd_cmd *cmd, int index) type = req_to_nbd_cmd_type(req); if (type == U32_MAX) - return -EIO; + return BLK_STS_IOERR; if (rq_data_dir(req) == WRITE && (config->flags & NBD_FLAG_READ_ONLY)) { dev_err_ratelimited(disk_to_dev(nbd->disk), "Write on read-only\n"); - return -EIO; + return BLK_STS_IOERR; } if (req->cmd_flags & REQ_FUA) @@ -674,11 +674,11 @@ static int nbd_send_cmd(struct nbd_device *nbd, struct nbd_cmd *cmd, int index) nsock->sent = sent; } set_bit(NBD_CMD_REQUEUED, &cmd->flags); - return (__force int)BLK_STS_RESOURCE; + return BLK_STS_RESOURCE; } dev_err_ratelimited(disk_to_dev(nbd->disk), "Send control failed (result %d)\n", result); - return -EAGAIN; + goto requeue; } send_pages: if (type != NBD_CMD_WRITE) @@ -715,12 +715,12 @@ static int nbd_send_cmd(struct nbd_device *nbd, struct nbd_cmd *cmd, int index) nsock->pending = req; nsock->sent = sent; set_bit(NBD_CMD_REQUEUED, &cmd->flags); - return (__force int)BLK_STS_RESOURCE; + return BLK_STS_RESOURCE; } dev_err(disk_to_dev(nbd->disk), "Send data failed (result %d)\n", result); - return -EAGAIN; + goto requeue; } /* * The completion might already have come in, @@ -737,7 +737,15 @@ static int nbd_send_cmd(struct nbd_device *nbd, struct nbd_cmd *cmd, int index) trace_nbd_payload_sent(req, handle); nsock->pending = NULL; nsock->sent = 0; - return 0; + __set_bit(NBD_CMD_INFLIGHT, &cmd->flags); + return BLK_STS_OK; +requeue: + /* retry on a different socket */ + dev_err_ratelimited(disk_to_dev(nbd->disk), + "Request send failed, requeueing\n"); + nbd_mark_nsock_dead(nbd, nsock, 1); + nbd_requeue_cmd(cmd); + return BLK_STS_OK; } static int nbd_read_reply(struct nbd_device *nbd, struct socket *sock, @@ -1018,7 +1026,7 @@ static blk_status_t nbd_handle_cmd(struct nbd_cmd *cmd, int index) struct nbd_device *nbd = cmd->nbd; struct nbd_config *config; struct nbd_sock *nsock; - int ret; + blk_status_t ret; lockdep_assert_held(&cmd->lock); @@ -1072,28 +1080,11 @@ static blk_status_t nbd_handle_cmd(struct nbd_cmd *cmd, int index) ret = BLK_STS_OK; goto out; } - /* - * Some failures are related to the link going down, so anything that - * returns EAGAIN can be retried on a different socket. - */ ret = nbd_send_cmd(nbd, cmd, index); - /* - * Access to this flag is protected by cmd->lock, thus it's safe to set - * the flag after nbd_send_cmd() succeed to send request to server. - */ - if (!ret) - __set_bit(NBD_CMD_INFLIGHT, &cmd->flags); - else if (ret == -EAGAIN) { - dev_err_ratelimited(disk_to_dev(nbd->disk), - "Request send failed, requeueing\n"); - nbd_mark_nsock_dead(nbd, nsock, 1); - nbd_requeue_cmd(cmd); - ret = BLK_STS_OK; - } out: mutex_unlock(&nsock->tx_lock); nbd_config_put(nbd); - return ret < 0 ? BLK_STS_IOERR : (__force blk_status_t)ret; + return ret; } static blk_status_t nbd_queue_rq(struct blk_mq_hw_ctx *hctx,
diff --git a/drivers/block/nbd.c b/drivers/block/nbd.c index 22a79a62cc4e..4ee76c39e3a5 100644 --- a/drivers/block/nbd.c +++ b/drivers/block/nbd.c @@ -588,11 +588,17 @@ static inline int was_interrupted(int result) return result == -ERESTARTSYS || result == -EINTR; } +struct send_res { + int result; + blk_status_t status; +}; + /* * Returns BLK_STS_RESOURCE if the caller should retry after a delay. Returns * -EAGAIN if the caller should requeue @cmd. Returns -EIO if sending failed. */ -static int nbd_send_cmd(struct nbd_device *nbd, struct nbd_cmd *cmd, int index) +static struct send_res nbd_send_cmd(struct nbd_device *nbd, struct nbd_cmd *cmd, + int index) { struct request *req = blk_mq_rq_from_pdu(cmd); struct nbd_config *config = nbd->config; @@ -614,13 +620,13 @@ static int nbd_send_cmd(struct nbd_device *nbd, struct nbd_cmd *cmd, int index) type = req_to_nbd_cmd_type(req); if (type == U32_MAX) - return -EIO; + return (struct send_res){ .result = -EIO }; if (rq_data_dir(req) == WRITE && (config->flags & NBD_FLAG_READ_ONLY)) { dev_err_ratelimited(disk_to_dev(nbd->disk), "Write on read-only\n"); - return -EIO; + return (struct send_res){ .result = -EIO }; } if (req->cmd_flags & REQ_FUA) @@ -674,11 +680,11 @@ static int nbd_send_cmd(struct nbd_device *nbd, struct nbd_cmd *cmd, int index) nsock->sent = sent; } set_bit(NBD_CMD_REQUEUED, &cmd->flags); - return (__force int)BLK_STS_RESOURCE; + return (struct send_res){ .status = BLK_STS_RESOURCE }; } dev_err_ratelimited(disk_to_dev(nbd->disk), "Send control failed (result %d)\n", result); - return -EAGAIN; + return (struct send_res){ .result = -EAGAIN }; } send_pages: if (type != NBD_CMD_WRITE) @@ -715,12 +721,14 @@ static int nbd_send_cmd(struct nbd_device *nbd, struct nbd_cmd *cmd, int index) nsock->pending = req; nsock->sent = sent; set_bit(NBD_CMD_REQUEUED, &cmd->flags); - return (__force int)BLK_STS_RESOURCE; + return (struct send_res){ + .status = BLK_STS_RESOURCE + }; } dev_err(disk_to_dev(nbd->disk), "Send data failed (result %d)\n", result); - return -EAGAIN; + return (struct send_res){ .result = -EAGAIN }; } /* * The completion might already have come in, @@ -737,7 +745,7 @@ static int nbd_send_cmd(struct nbd_device *nbd, struct nbd_cmd *cmd, int index) trace_nbd_payload_sent(req, handle); nsock->pending = NULL; nsock->sent = 0; - return 0; + return (struct send_res){}; } static int nbd_read_reply(struct nbd_device *nbd, struct socket *sock, @@ -1018,7 +1026,8 @@ static blk_status_t nbd_handle_cmd(struct nbd_cmd *cmd, int index) struct nbd_device *nbd = cmd->nbd; struct nbd_config *config; struct nbd_sock *nsock; - int ret; + struct send_res send_res; + blk_status_t ret; lockdep_assert_held(&cmd->lock); @@ -1076,14 +1085,15 @@ static blk_status_t nbd_handle_cmd(struct nbd_cmd *cmd, int index) * Some failures are related to the link going down, so anything that * returns EAGAIN can be retried on a different socket. */ - ret = nbd_send_cmd(nbd, cmd, index); - /* - * Access to this flag is protected by cmd->lock, thus it's safe to set - * the flag after nbd_send_cmd() succeed to send request to server. - */ - if (!ret) + send_res = nbd_send_cmd(nbd, cmd, index); + ret = send_res.result < 0 ? BLK_STS_IOERR : send_res.status; + if (ret == BLK_STS_OK) { + /* + * cmd->lock is held. Hence, it's safe to set this flag after + * nbd_send_cmd() succeeded sending the request to the server. + */ __set_bit(NBD_CMD_INFLIGHT, &cmd->flags); - else if (ret == -EAGAIN) { + } else if (send_res.result == -EAGAIN) { dev_err_ratelimited(disk_to_dev(nbd->disk), "Request send failed, requeueing\n"); nbd_mark_nsock_dead(nbd, nsock, 1); @@ -1093,7 +1103,7 @@ static blk_status_t nbd_handle_cmd(struct nbd_cmd *cmd, int index) out: mutex_unlock(&nsock->tx_lock); nbd_config_put(nbd); - return ret < 0 ? BLK_STS_IOERR : (__force blk_status_t)ret; + return ret; } static blk_status_t nbd_queue_rq(struct blk_mq_hw_ctx *hctx,
Make it again possible for sparse to verify that blk_status_t and Unix error codes are used in the proper context by making nbd_send_cmd() return a struct instead of an integer. Additionally, move a misplaced comment to where it should occur. No functionality has been changed. Cc: Christoph Hellwig <hch@lst.de> Suggested-by: Christoph Hellwig <hch@lst.de> Signed-off-by: Bart Van Assche <bvanassche@acm.org> --- drivers/block/nbd.c | 44 +++++++++++++++++++++++++++----------------- 1 file changed, 27 insertions(+), 17 deletions(-)