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Fri, 30 Jan 2026 18:21:03 +0000 (GMT) From: Nilay Shroff To: linux-nvme@lists.infradead.org Cc: kbusch@kernel.org, axboe@kernel.dk, hch@lst.de, sagi@grimberg.me, hare@suse.de, dwagner@suse.de, wenxiong@linux.ibm.com, gjoyce@ibm.com, Nilay Shroff Subject: [PATCH 5/7] nvme: export I/O failure count when no path is available via sysfs Date: Fri, 30 Jan 2026 23:50:22 +0530 Message-ID: <20260130182028.885089-6-nilay@linux.ibm.com> X-Mailer: git-send-email 2.52.0 In-Reply-To: <20260130182028.885089-1-nilay@linux.ibm.com> References: <20260130182028.885089-1-nilay@linux.ibm.com> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-TM-AS-GCONF: 00 X-Proofpoint-GUID: 9c1KRAX6UsfwX_Z7oFnEpvN3kh0aW_KJ X-Proofpoint-Spam-Details-Enc: AW1haW4tMjYwMTMwMDE1MCBTYWx0ZWRfXz+Jf3WjJAW7d PYmHxcg8rQaayxTPZc1kKAJ7yM1tqlHCsgkWvuo1ZFBdBsHx8m7ZPKgy7vcSOJFQO2Dho3xgM80 JezQxeQ5pqaPe5Hv9qFXg9bEOuQOVRlGAWzc/1PHeYsSeg/uFol2o04YE6FMprEI2Y8deiUlQzm OiRboItbHKEYinb5CUcTV72mj/2h53NjswL1sdfrBqjHAP6cKqNTGWZJSzFFhtDe4T4HDUrL/sk MkortPU+vZIh1H98H9eRIR6uYLIE6ecE/r0v/mMmBxJUyw9PebLd3kdow6lDcClRhM+K/0qg4Fw qeLnY7lsQb1VnjmwWQ4a9NwPES0ZINJ8WuXo2Ha+aB53p2vyu6LQDpMRAc0+1cIOAp0fN2iXle2 DfeTqlRXgyG1ex11D1DsYOVNEBPSqft3KqUL3jdQj+KpplIPZS99TTmHwtUUZlQtelGx9iU3uiq OQu5rjEhcQ9B7NwOsEQ== X-Authority-Analysis: v=2.4 cv=Zs3g6t7G c=1 sm=1 tr=0 ts=697cf698 cx=c_pps a=aDMHemPKRhS1OARIsFnwRA==:117 a=aDMHemPKRhS1OARIsFnwRA==:17 a=vUbySO9Y5rIA:10 a=sWKEhP36mHoA:10 a=VkNPw1HP01LnGYTKEx00:22 a=VnNF1IyMAAAA:8 a=6zb8lMvYnNi-4QC_6R8A:9 X-Proofpoint-ORIG-GUID: 9c1KRAX6UsfwX_Z7oFnEpvN3kh0aW_KJ X-Proofpoint-Virus-Version: vendor=baseguard engine=ICAP:2.0.293,Aquarius:18.0.1121,Hydra:6.1.51,FMLib:17.12.100.49 definitions=2026-01-30_02,2026-01-30_04,2025-10-01_01 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 clxscore=1015 lowpriorityscore=0 adultscore=0 phishscore=0 suspectscore=0 bulkscore=0 impostorscore=0 priorityscore=1501 malwarescore=0 spamscore=0 classifier=typeunknown authscore=0 authtc= authcc= route=outbound adjust=0 reason=mlx scancount=1 engine=8.19.0-2601150000 definitions=main-2601300150 X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20260130_102118_596906_72DCB119 X-CRM114-Status: GOOD ( 17.12 ) X-BeenThere: linux-nvme@lists.infradead.org X-Mailman-Version: 2.1.34 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: "Linux-nvme" Errors-To: linux-nvme-bounces+linux-nvme=archiver.kernel.org@lists.infradead.org When I/O is submitted to the NVMe namespace head and no available path can handle the request, the driver fails the I/O immediately. Currently, such failures are only reported via kernel log messages, which may be lost over time since dmesg is a circular buffer. Add a new sysfs counter, fail_no_available_path, to expose the number of I/Os that failed due to the absence of an available path. This provides persistent visibility into path-related I/O failures and can help users diagnose the cause of I/O errors. This counter can also be consumed by monitoring tools such as nvme-top. Signed-off-by: Nilay Shroff --- drivers/nvme/host/multipath.c | 11 +++++++++++ drivers/nvme/host/nvme.h | 2 ++ drivers/nvme/host/sysfs.c | 1 + 3 files changed, 14 insertions(+) diff --git a/drivers/nvme/host/multipath.c b/drivers/nvme/host/multipath.c index 4e5f8523ca40..85641e8852ad 100644 --- a/drivers/nvme/host/multipath.c +++ b/drivers/nvme/host/multipath.c @@ -544,6 +544,7 @@ static void nvme_ns_head_submit_bio(struct bio *bio) dev_warn_ratelimited(dev, "no available path - failing I/O\n"); bio_io_error(bio); + head->fail_no_available_path++; } srcu_read_unlock(&head->srcu, srcu_idx); @@ -1189,6 +1190,16 @@ static ssize_t requeue_no_usable_path_show(struct device *dev, } DEVICE_ATTR_RO(requeue_no_usable_path); +static ssize_t fail_no_available_path_show(struct device *dev, + struct device_attribute *attr, char *buf) +{ + struct gendisk *disk = dev_to_disk(dev); + struct nvme_ns_head *head = disk->private_data; + + return sysfs_emit(buf, "%llu\n", head->fail_no_available_path); +} +DEVICE_ATTR_RO(fail_no_available_path); + static int nvme_lookup_ana_group_desc(struct nvme_ctrl *ctrl, struct nvme_ana_group_desc *desc, void *data) { diff --git a/drivers/nvme/host/nvme.h b/drivers/nvme/host/nvme.h index 5836e4c557a2..66bd4db1fe0f 100644 --- a/drivers/nvme/host/nvme.h +++ b/drivers/nvme/host/nvme.h @@ -510,6 +510,7 @@ struct nvme_ns_head { struct delayed_work remove_work; unsigned int delayed_removal_secs; u64 requeue_no_usable_path; + u64 fail_no_available_path; #define NVME_NSHEAD_DISK_LIVE 0 #define NVME_NSHEAD_QUEUE_IF_NO_PATH 1 struct nvme_ns __rcu *current_path[]; @@ -1007,6 +1008,7 @@ extern struct device_attribute dev_attr_numa_nodes; extern struct device_attribute dev_attr_delayed_removal_secs; extern struct device_attribute dev_attr_multipath_failover_count; extern struct device_attribute dev_attr_requeue_no_usable_path; +extern struct device_attribute dev_attr_fail_no_available_path; extern struct device_attribute subsys_attr_iopolicy; static inline bool nvme_disk_is_ns_head(struct gendisk *disk) diff --git a/drivers/nvme/host/sysfs.c b/drivers/nvme/host/sysfs.c index 84d33445a578..c23d9a0ba3f4 100644 --- a/drivers/nvme/host/sysfs.c +++ b/drivers/nvme/host/sysfs.c @@ -285,6 +285,7 @@ static struct attribute *nvme_ns_attrs[] = { &dev_attr_delayed_removal_secs.attr, &dev_attr_multipath_failover_count.attr, &dev_attr_requeue_no_usable_path.attr, + &dev_attr_fail_no_available_path.attr, #endif &dev_attr_io_passthru_err_log_enabled.attr, &dev_attr_io_command_retries.attr, -- 2.52.0