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Tue, 4 Nov 2025 10:45:41 +0000 (GMT) From: Nilay Shroff To: linux-nvme@lists.infradead.org Cc: hare@suse.de, hch@lst.de, kbusch@kernel.org, sagi@grimberg.me, dwagner@suse.de, axboe@kernel.dk, gjoyce@ibm.com Subject: [RFC PATCHv4 3/6] nvme: add generic debugfs support Date: Tue, 4 Nov 2025 16:15:18 +0530 Message-ID: <20251104104533.138481-4-nilay@linux.ibm.com> X-Mailer: git-send-email 2.51.0 In-Reply-To: <20251104104533.138481-1-nilay@linux.ibm.com> References: <20251104104533.138481-1-nilay@linux.ibm.com> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-TM-AS-GCONF: 00 X-Proofpoint-ORIG-GUID: _TfryLSd_L8M3PcWkW_xeqvzLAE_OfH3 X-Proofpoint-GUID: _TfryLSd_L8M3PcWkW_xeqvzLAE_OfH3 X-Proofpoint-Spam-Details-Enc: AW1haW4tMjUxMTAxMDAyMSBTYWx0ZWRfXxc958q54O30a SjjknNpyL68bsK47pPPeoL4v3XVmzMNt8sL7zyy039wNxPfB9hagzlv9lqkC0r/BA/E/DfTUTeB IQu4dPe7FM4pUXVGvwEpvTZMCKDMVeLeNnwnRAZhlPAi+iKSxp0Uk0SPIgWLVv43/+U/4C3WIIY xTzMGtzKfDGMr8qVCihjEhOo4W8p7WgWREYu6E4VcstoQGKAyIyaN89j+3hubLuKsuwpD0SpP5y EJc/aWWIufhCbNks49mVASPH62lYqcG3x1Wwg+N3MGxz5ROvQYCSuRjbixVU5Bo0dbdCUaI0e22 YNufp8uwqbJw7wwwZTSqvWb32LyuUZAU/vCjg4/dp/juOnYQEsk4WGY30a0XGim0F+BDbRMLurf rwEA3L74blvzvyzDWIa027lhRVuUYg== X-Authority-Analysis: v=2.4 cv=U6qfzOru c=1 sm=1 tr=0 ts=6909d95f cx=c_pps a=5BHTudwdYE3Te8bg5FgnPg==:117 a=5BHTudwdYE3Te8bg5FgnPg==:17 a=6UeiqGixMTsA:10 a=VkNPw1HP01LnGYTKEx00:22 a=VnNF1IyMAAAA:8 a=RurgEnbhPsFkkpbWVXEA:9 a=cPQSjfK2_nFv0Q5t_7PE:22 X-Proofpoint-Virus-Version: vendor=baseguard engine=ICAP:2.0.293,Aquarius:18.0.1121,Hydra:6.1.9,FMLib:17.12.100.49 definitions=2025-11-03_06,2025-11-03_03,2025-10-01_01 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 bulkscore=0 adultscore=0 impostorscore=0 spamscore=0 phishscore=0 clxscore=1015 malwarescore=0 lowpriorityscore=0 suspectscore=0 priorityscore=1501 classifier=typeunknown authscore=0 authtc= authcc= route=outbound adjust=0 reason=mlx scancount=1 engine=8.19.0-2510240000 definitions=main-2511010021 X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20251104_024556_592159_422F49E3 X-CRM114-Status: GOOD ( 23.41 ) 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 Add generic infrastructure for creating and managing debugfs files in the NVMe module. This introduces helper APIs that allow NVMe drivers to register and unregister debugfs entries, along with a reusable attribute structure for defining new debugfs files. The implementation uses seq_file interfaces to safely expose per-NS and per-NS-head statistics, while supporting both simple show callbacks and full seq_operations. Reviewed-by: Hannes Reinecke Signed-off-by: Nilay Shroff --- drivers/nvme/host/Makefile | 2 +- drivers/nvme/host/core.c | 3 + drivers/nvme/host/debugfs.c | 138 ++++++++++++++++++++++++++++++++++ drivers/nvme/host/multipath.c | 2 + drivers/nvme/host/nvme.h | 10 +++ 5 files changed, 154 insertions(+), 1 deletion(-) create mode 100644 drivers/nvme/host/debugfs.c diff --git a/drivers/nvme/host/Makefile b/drivers/nvme/host/Makefile index 6414ec968f99..7962dfc3b2ad 100644 --- a/drivers/nvme/host/Makefile +++ b/drivers/nvme/host/Makefile @@ -10,7 +10,7 @@ obj-$(CONFIG_NVME_FC) += nvme-fc.o obj-$(CONFIG_NVME_TCP) += nvme-tcp.o obj-$(CONFIG_NVME_APPLE) += nvme-apple.o -nvme-core-y += core.o ioctl.o sysfs.o pr.o +nvme-core-y += core.o ioctl.o sysfs.o pr.o debugfs.o nvme-core-$(CONFIG_NVME_VERBOSE_ERRORS) += constants.o nvme-core-$(CONFIG_TRACING) += trace.o nvme-core-$(CONFIG_NVME_MULTIPATH) += multipath.o diff --git a/drivers/nvme/host/core.c b/drivers/nvme/host/core.c index 47f375c63d2d..c15dfcaf3de2 100644 --- a/drivers/nvme/host/core.c +++ b/drivers/nvme/host/core.c @@ -4187,6 +4187,8 @@ static void nvme_alloc_ns(struct nvme_ctrl *ctrl, struct nvme_ns_info *info) if (device_add_disk(ctrl->device, ns->disk, nvme_ns_attr_groups)) goto out_cleanup_ns_from_list; + nvme_debugfs_register(ns->disk); + if (!nvme_ns_head_multipath(ns->head)) nvme_add_ns_cdev(ns); @@ -4276,6 +4278,7 @@ static void nvme_ns_remove(struct nvme_ns *ns) nvme_mpath_remove_sysfs_link(ns); + nvme_debugfs_unregister(ns->disk); del_gendisk(ns->disk); mutex_lock(&ns->ctrl->namespaces_lock); diff --git a/drivers/nvme/host/debugfs.c b/drivers/nvme/host/debugfs.c new file mode 100644 index 000000000000..6bb57c4b5c3b --- /dev/null +++ b/drivers/nvme/host/debugfs.c @@ -0,0 +1,138 @@ +// SPDX-License-Identifier: GPL-2.0 +/* + * Copyright (c) 2025 IBM Corporation + * Nilay Shroff + */ + +#include +#include + +#include "nvme.h" + +struct nvme_debugfs_attr { + const char *name; + umode_t mode; + int (*show)(void *data, struct seq_file *m); + ssize_t (*write)(void *data, const char __user *buf, size_t count, + loff_t *ppos); + const struct seq_operations *seq_ops; +}; + +struct nvme_debugfs_ctx { + void *data; + struct nvme_debugfs_attr *attr; + int srcu_idx; +}; + +static int nvme_debugfs_show(struct seq_file *m, void *v) +{ + struct nvme_debugfs_ctx *ctx = m->private; + void *data = ctx->data; + struct nvme_debugfs_attr *attr = ctx->attr; + + return attr->show(data, m); +} + +static int nvme_debugfs_open(struct inode *inode, struct file *file) +{ + void *data = inode->i_private; + struct nvme_debugfs_attr *attr = debugfs_get_aux(file); + struct nvme_debugfs_ctx *ctx; + struct seq_file *m; + int ret; + + ctx = kzalloc(sizeof(*ctx), GFP_KERNEL); + if (WARN_ON_ONCE(!ctx)) + return -ENOMEM; + + ctx->data = data; + ctx->attr = attr; + + if (attr->seq_ops) { + ret = seq_open(file, attr->seq_ops); + if (ret) { + kfree(ctx); + return ret; + } + m = file->private_data; + m->private = ctx; + return ret; + } + + if (WARN_ON_ONCE(!attr->show)) { + kfree(ctx); + return -EPERM; + } + + return single_open(file, nvme_debugfs_show, ctx); +} + +static ssize_t nvme_debugfs_write(struct file *file, const char __user *buf, + size_t count, loff_t *ppos) +{ + struct seq_file *m = file->private_data; + struct nvme_debugfs_ctx *ctx = m->private; + struct nvme_debugfs_attr *attr = ctx->attr; + + if (!attr->write) + return -EPERM; + + return attr->write(ctx->data, buf, count, ppos); +} + +static int nvme_debugfs_release(struct inode *inode, struct file *file) +{ + struct seq_file *m = file->private_data; + struct nvme_debugfs_ctx *ctx = m->private; + struct nvme_debugfs_attr *attr = ctx->attr; + int ret; + + if (attr->seq_ops) + ret = seq_release(inode, file); + else + ret = single_release(inode, file); + + kfree(ctx); + return ret; +} + +static const struct file_operations nvme_debugfs_fops = { + .owner = THIS_MODULE, + .open = nvme_debugfs_open, + .read = seq_read, + .write = nvme_debugfs_write, + .llseek = seq_lseek, + .release = nvme_debugfs_release, +}; + + +static const struct nvme_debugfs_attr nvme_mpath_debugfs_attrs[] = { + {}, +}; + +static const struct nvme_debugfs_attr nvme_ns_debugfs_attrs[] = { + {}, +}; + +static void nvme_debugfs_create_files(struct request_queue *q, + const struct nvme_debugfs_attr *attr, void *data) +{ + if (WARN_ON_ONCE(!q->debugfs_dir)) + return; + + for (; attr->name; attr++) + debugfs_create_file_aux(attr->name, attr->mode, q->debugfs_dir, + data, (void *)attr, &nvme_debugfs_fops); +} + +void nvme_debugfs_register(struct gendisk *disk) +{ + const struct nvme_debugfs_attr *attr; + + if (nvme_disk_is_ns_head(disk)) + attr = nvme_mpath_debugfs_attrs; + else + attr = nvme_ns_debugfs_attrs; + + nvme_debugfs_create_files(disk->queue, attr, disk->private_data); +} diff --git a/drivers/nvme/host/multipath.c b/drivers/nvme/host/multipath.c index 55dc28375662..047dd9da9cbf 100644 --- a/drivers/nvme/host/multipath.c +++ b/drivers/nvme/host/multipath.c @@ -1086,6 +1086,7 @@ static void nvme_remove_head(struct nvme_ns_head *head) nvme_cdev_del(&head->cdev, &head->cdev_device); synchronize_srcu(&head->srcu); + nvme_debugfs_unregister(head->disk); del_gendisk(head->disk); } nvme_put_ns_head(head); @@ -1192,6 +1193,7 @@ static void nvme_mpath_set_live(struct nvme_ns *ns) } nvme_add_ns_head_cdev(head); kblockd_schedule_work(&head->partition_scan_work); + nvme_debugfs_register(head->disk); } nvme_mpath_add_sysfs_link(ns->head); diff --git a/drivers/nvme/host/nvme.h b/drivers/nvme/host/nvme.h index 715c7053054c..1c1ec2a7f9ad 100644 --- a/drivers/nvme/host/nvme.h +++ b/drivers/nvme/host/nvme.h @@ -1000,6 +1000,16 @@ static inline int nvme_data_dir(const enum req_op op) return NVME_STAT_OTHER; } +void nvme_debugfs_register(struct gendisk *disk); +static inline void nvme_debugfs_unregister(struct gendisk *disk) +{ + /* + * Nothing to do for now. When the request queue is unregistered, + * all files under q->debugfs_dir are recursively deleted. + * This is just a placeholder; the compiler will optimize it out. + */ +} + #ifdef CONFIG_NVME_MULTIPATH static inline bool nvme_ctrl_use_ana(struct nvme_ctrl *ctrl) { -- 2.51.0