FAILED: patch "[PATCH] mmc: block: ensure error propagation for non-blk" failed to apply to 5.10-stable tree

The patch below does not apply to the 5.10-stable tree.
If someone wants it applied there, or to any other stable or longterm tree, then please email the backport, including the original git commit id to <[email protected]>.

To reproduce the conflict and resubmit, you may use the following commands:

git fetch https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/ linux-5.10.y
git checkout FETCH_HEAD
git cherry-pick -x 003fb0a51162d940f25fc35e70b0996a12c9e08a
# <resolve conflicts, build, test, etc.>
git commit -s
git send-email --to '<[email protected]>' --in-reply-to '2023052608-hybrid-jugular-3bc2@gregkh' --subject-prefix 'PATCH 5.10.y' HEAD^..

Possible dependencies:

003fb0a51162 ("mmc: block: ensure error propagation for non-blk") b84ba30b6c7a ("block: remove the gendisk argument to blk_execute_rq") 4054cff92c35 ("block: remove blk-exec.c")
0bf6d96cb829 ("block: remove blk_{get,put}_request")
4abafdc4360d ("block: remove the initialize_rq_fn blk_mq_ops method") 68ec3b819a5d ("scsi: add a scsi_alloc_request helper")
5a72e899ceb4 ("block: add a struct io_comp_batch argument to fops->iopoll()") 013a7f954381 ("block: provide helpers for rq_list manipulation") afd7de03c526 ("block: remove some blk_mq_hw_ctx debugfs entries") 3e08773c3841 ("block: switch polling to be bio based")
6ce913fe3eee ("block: rename REQ_HIPRI to REQ_POLLED")
d729cf9acb93 ("io_uring: don't sleep when polling for I/O") ef99b2d37666 ("block: replace the spin argument to blk_iopoll with a flags argument") 28a1ae6b9dab ("blk-mq: remove blk_qc_t_valid")
efbabbe121f9 ("blk-mq: remove blk_qc_t_to_tag and blk_qc_t_is_internal") c6699d6fe0ff ("blk-mq: factor out a "classic" poll helper") f70299f0d58e ("blk-mq: factor out a blk_qc_to_hctx helper") 71fc3f5e2c00 ("block: don't try to poll multi-bio I/Os in __blkdev_direct_IO") 349302da8352 ("block: improve batched tag allocation")
0f38d7664615 ("blk-mq: cleanup blk_mq_submit_bio")

thanks,

greg k-h

------------------ original commit in Linus's tree ------------------

From 003fb0a51162d940f25fc35e70b0996a12c9e08a Mon Sep 17 00:00:00 2001
From: Christian Loehle <[email protected]>
Date: Wed, 26 Apr 2023 16:59:39 +0000
Subject: [PATCH] mmc: block: ensure error propagation for non-blk

Requests to the mmc layer usually come through a block device IO. The exceptions are the ioctl interface, RPMB chardev ioctl and debugfs, which issue their own blk_mq requests through blk_execute_rq and do not query the BLK_STS error but the mmcblk-internal drv_op_result. This patch ensures that drv_op_result defaults to an error and has to be overwritten by the operation to be considered successful.

The behavior leads to a bug where the request never propagates the error, e.g. by directly erroring out at mmc_blk_mq_issue_rq if mmc_blk_part_switch fails. The ioctl caller of the rpmb chardev then can never see an error (BLK_STS_IOERR, but drv_op_result is unchanged) and thus may assume that their call executed successfully when it did not.

While always checking the blk_execute_rq return value would be advised, let's eliminate the error by always setting drv_op_result as -EIO to be overwritten on success (or other error)

index 00c33edb9fb9..d920c4178389 100644
@@ -264,6 +264,7 @@ static ssize_t power_ro_lock_store(struct device *dev,
 		goto out_put;
 	}
 	req_to_mmc_queue_req(req)->drv_op = MMC_DRV_OP_BOOT_WP;
+	req_to_mmc_queue_req(req)->drv_op_result = -EIO;
 	blk_execute_rq(req, false);
 	ret = req_to_mmc_queue_req(req)->drv_op_result;
 	blk_mq_free_request(req);

@@ -651,6 +652,7 @@ static int mmc_blk_ioctl_cmd(struct mmc_blk_data *md,
 	idatas[0] = idata;
 	req_to_mmc_queue_req(req)->drv_op =
 		rpmb ? MMC_DRV_OP_IOCTL_RPMB : MMC_DRV_OP_IOCTL;
+	req_to_mmc_queue_req(req)->drv_op_result = -EIO;
 	req_to_mmc_queue_req(req)->drv_op_data = idatas;
 	req_to_mmc_queue_req(req)->ioc_count = 1;
 	blk_execute_rq(req, false);

@@ -722,6 +724,7 @@ static int mmc_blk_ioctl_multi_cmd(struct mmc_blk_data *md,
 	}
 	req_to_mmc_queue_req(req)->drv_op =
 		rpmb ? MMC_DRV_OP_IOCTL_RPMB : MMC_DRV_OP_IOCTL;
+	req_to_mmc_queue_req(req)->drv_op_result = -EIO;
 	req_to_mmc_queue_req(req)->drv_op_data = idata;
 	req_to_mmc_queue_req(req)->ioc_count = n;
 	blk_execute_rq(req, false);

@@ -2806,6 +2809,7 @@ static int mmc_dbg_card_status_get(void *data, u64 *val)
 	if (IS_ERR(req))
 		return PTR_ERR(req);
 	req_to_mmc_queue_req(req)->drv_op = MMC_DRV_OP_GET_CARD_STATUS;
+	req_to_mmc_queue_req(req)->drv_op_result = -EIO;
 	blk_execute_rq(req, false);
 	ret = req_to_mmc_queue_req(req)->drv_op_result;
 	if (ret >= 0) {

@@ -2844,6 +2848,7 @@ static int mmc_ext_csd_open(struct inode *inode, struct file *filp)
 		goto out_free;
 	}
 	req_to_mmc_queue_req(req)->drv_op = MMC_DRV_OP_GET_EXT_CSD;
+	req_to_mmc_queue_req(req)->drv_op_result = -EIO;
 	req_to_mmc_queue_req(req)->drv_op_data = &ext_csd;
 	blk_execute_rq(req, false);
 	err = req_to_mmc_queue_req(req)->drv_op_result;