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Tue, 05 May 2026 00:47:44 -0700 (PDT) From: Md Haris Iqbal To: linux-block@vger.kernel.org, linux-rdma@vger.kernel.org Cc: linux-kernel@vger.kernel.org, axboe@kernel.dk, bvanassche@acm.org, hch@lst.de, jgg@ziepe.ca, leon@kernel.org, jinpu.wang@ionos.com, Md Haris Iqbal , Jia Li Subject: [PATCH 12/13] block/brmr: server: sysfs interface functions Date: Tue, 5 May 2026 09:46:24 +0200 Message-ID: <20260505074644.195453-13-haris.iqbal@ionos.com> X-Mailer: git-send-email 2.43.0 In-Reply-To: <20260505074644.195453-1-haris.iqbal@ionos.com> References: <20260505074644.195453-1-haris.iqbal@ionos.com> Precedence: bulk X-Mailing-List: linux-rdma@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Add the BRMR server sysfs interface used to register and unregister backing block devices. Writes to /sys/devices/virtual/brmr-server/ctl/map_device open the named block device, validate or initialise its on-disk metadata, and register it with RMR as the IO store for the named pool. This file is not compiled until the modules are wired into the build in a later patch in this series. Signed-off-by: Md Haris Iqbal Signed-off-by: Jia Li --- drivers/block/brmr/brmr-srv-sysfs.c | 707 ++++++++++++++++++++++++++++ 1 file changed, 707 insertions(+) create mode 100644 drivers/block/brmr/brmr-srv-sysfs.c diff --git a/drivers/block/brmr/brmr-srv-sysfs.c b/drivers/block/brmr/brmr-srv-sysfs.c new file mode 100644 index 000000000000..7e413eb258bb --- /dev/null +++ b/drivers/block/brmr/brmr-srv-sysfs.c @@ -0,0 +1,707 @@ +// SPDX-License-Identifier: GPL-2.0-or-later +/* + * Block device over RMR (BRMR) + * + * Copyright (c) 2026 IONOS SE + */ +#include +#include +#include +#include +#include +#include +#include +#include +#include + +#include "brmr-srv.h" +#include "rmr-srv.h" + +#undef pr_fmt +#define pr_fmt(fmt) KBUILD_MODNAME " L" __stringify(__LINE__) ": " fmt + +static struct class *rmr_str_class; +static struct device *rmr_ctl_dev; +static struct device *rmr_strs_dev; + +enum { + BRMR_SRV_STR_OPT_ERR = 0, + BRMR_SRV_STR_OPT_DEVICE = 1 << 0, + BRMR_SRV_STR_OPT_POOL = 1 << 2, + BRMR_SRV_STR_OPT_MAPPED_SIZE = 1 << 3, + BRMR_SRV_STR_OPT_MODE = 1 << 4, +}; + +static const unsigned int rmr_str_opt_mandatory[] = { + BRMR_SRV_STR_OPT_POOL, + BRMR_SRV_STR_OPT_DEVICE, + BRMR_SRV_STR_OPT_MAPPED_SIZE, +}; + +static const match_table_t rmr_str_opt_tokens = { + { BRMR_SRV_STR_OPT_POOL, "pool=%s" }, + { BRMR_SRV_STR_OPT_DEVICE, "device=%s" }, + { BRMR_SRV_STR_OPT_MAPPED_SIZE, "mapped_size=%s" }, + { BRMR_SRV_STR_OPT_MODE, "mode=%s" }, + { BRMR_SRV_STR_OPT_ERR, NULL }, +}; + +struct brmr_srv_str_options { + char *pool; + char *device; + unsigned long mapped_size; +}; + +static void brmr_srv_remove_store(struct brmr_srv_blk_dev *dev, struct kobj_attribute *attr, + bool delete) +{ + mutex_lock(&store_mutex); + + blk_str_destroy_sysfs_files(dev, &attr->attr); + + brmr_srv_blk_close(dev, delete); + + pr_info("put blkdev %s\n", dev->bdev->bd_disk->disk_name); + bdev_fput(dev->bdev_file); + + pr_info("%s store %s, store name %s.\n", (delete ? "Delete" : "Remove"), + dev->name, dev->poolname); + brmr_srv_blk_destroy(dev); + mutex_unlock(&store_mutex); +} + +static int brmr_srv_parse_add_opts(const char *buf, struct brmr_srv_str_options *opt, + unsigned int *replace) +{ + char *options, *sep_opt; + char *p; + substring_t args[MAX_OPT_ARGS]; + int opt_mask = 0; + int token; + int ret = -EINVAL; + int i; + + options = kstrdup(buf, GFP_KERNEL); + if (!options) + return -ENOMEM; + + sep_opt = strstrip(options); + while ((p = strsep(&sep_opt, " ")) != NULL) { + if (!*p) + continue; + + token = match_token(p, rmr_str_opt_tokens, args); + opt_mask |= token; + + switch (token) { + case BRMR_SRV_STR_OPT_POOL: + p = match_strdup(args); + if (!p) { + ret = -ENOMEM; + goto out; + } + if (strlen(p) > NAME_MAX) { + pr_err("add_store: pool name is too long\n"); + ret = -EINVAL; + kfree(p); + goto out; + } + strscpy(opt->pool, p, NAME_MAX); + kfree(p); + break; + + case BRMR_SRV_STR_OPT_DEVICE: + p = match_strdup(args); + if (!p) { + ret = -ENOMEM; + goto out; + } + if (strlen(p) > NAME_MAX) { + pr_err("add_store: device name is too long\n"); + ret = -EINVAL; + kfree(p); + goto out; + } + strscpy(opt->device, p, NAME_MAX); + kfree(p); + break; + + case BRMR_SRV_STR_OPT_MAPPED_SIZE: + p = match_strdup(args); + if (!p) { + ret = -ENOMEM; + goto out; + } + + ret = kstrtoul(p, 0, &opt->mapped_size); + if (ret) { + pr_err("mapped_size isn't an integer: %d\n", ret); + kfree(p); + goto out; + } + + if (opt->mapped_size == 0) { + pr_err("mapped_size cannot be 0\n"); + ret = -EINVAL; + kfree(p); + goto out; + } + + kfree(p); + break; + + case BRMR_SRV_STR_OPT_MODE: + if (!replace) { + pr_err("%s: mode option not supported here\n", __func__); + ret = -EINVAL; + goto out; + } + + p = match_strdup(args); + if (!p) { + ret = -ENOMEM; + goto out; + } + + if (!strcmp(p, "replace")) { + *replace = true; + } else { + pr_err("%s: Unknown mode '%s'\n", __func__, p); + ret = -EINVAL; + kfree(p); + goto out; + } + kfree(p); + break; + + default: + pr_err("add_store: Unknown parameter or missing value '%s'\n", + p); + ret = -EINVAL; + goto out; + } + } + + for (i = 0; i < ARRAY_SIZE(rmr_str_opt_mandatory); i++) { + if ((opt_mask & rmr_str_opt_mandatory[i])) { + ret = 0; + } else { + pr_err("add_store: Parameters missing\n"); + ret = -EINVAL; + break; + } + } + +out: + kfree(options); + return ret; +} + +static ssize_t blk_str_dev_size_show(struct kobject *kobj, + struct kobj_attribute *attr, char *page) +{ + struct brmr_srv_blk_dev *dev; + + dev = container_of(kobj, struct brmr_srv_blk_dev, kobj); + + return sysfs_emit(page, "%llu\n", dev->dev_size); +} + +static struct kobj_attribute blk_str_dev_size_attr = + __ATTR(dev_size, 0644, blk_str_dev_size_show, NULL); + +static ssize_t blk_str_mapped_size_show(struct kobject *kobj, + struct kobj_attribute *attr, char *page) +{ + struct brmr_srv_blk_dev *dev; + + dev = container_of(kobj, struct brmr_srv_blk_dev, kobj); + + return sysfs_emit(page, "%llu\n", dev->mapped_size); +} + +static struct kobj_attribute blk_str_mapped_size_attr = + __ATTR(mapped_size, 0644, blk_str_mapped_size_show, NULL); + +static ssize_t blk_str_bdev_name_show(struct kobject *kobj, + struct kobj_attribute *attr, char *page) +{ + struct brmr_srv_blk_dev *dev; + + dev = container_of(kobj, struct brmr_srv_blk_dev, kobj); + + return sysfs_emit(page, "%s\n", dev->name); +} + +static struct kobj_attribute blk_str_bdev_name_attr = + __ATTR(bdev_name, 0644, blk_str_bdev_name_show, NULL); + +static ssize_t blk_str_remove_store_show(struct kobject *kobj, + struct kobj_attribute *attr, + char *page) +{ + return scnprintf(page, PAGE_SIZE, "Usage: echo 1 to remove the store\n"); +} + +static ssize_t blk_str_remove_store_store(struct kobject *kobj, + struct kobj_attribute *attr, + const char *buf, size_t count) +{ + struct brmr_srv_blk_dev *dev; + + dev = container_of(kobj, struct brmr_srv_blk_dev, kobj); + if (!sysfs_streq(buf, "1")) { + pr_err("%s, %s unknown value: '%s'\n", + dev->name, attr->attr.name, buf); + return -EINVAL; + } + + brmr_srv_remove_store(dev, attr, false); + + return count; +} + +static struct kobj_attribute blk_str_remove_store_attr = + __ATTR(remove_store, 0644, + blk_str_remove_store_show, blk_str_remove_store_store); + +static ssize_t blk_str_delete_store_show(struct kobject *kobj, + struct kobj_attribute *attr, + char *page) +{ + return scnprintf(page, PAGE_SIZE, "Usage: echo 1 to delete the store\n"); +} + +static ssize_t blk_str_delete_store_store(struct kobject *kobj, + struct kobj_attribute *attr, + const char *buf, size_t count) +{ + struct brmr_srv_blk_dev *dev; + + dev = container_of(kobj, struct brmr_srv_blk_dev, kobj); + if (!sysfs_streq(buf, "1")) { + pr_err("%s, %s unknown value: '%s'\n", + dev->name, attr->attr.name, buf); + return -EINVAL; + } + + brmr_srv_remove_store(dev, attr, true); + + return count; +} + +static struct kobj_attribute blk_str_delete_store_attr = + __ATTR(delete_store, 0644, + blk_str_delete_store_show, blk_str_delete_store_store); + +static ssize_t state_show(struct kobject *kobj, + struct kobj_attribute *attr, char *page) +{ + struct brmr_srv_blk_dev *dev; + size_t count = 0; + + dev = container_of(kobj, struct brmr_srv_blk_dev, kobj); + + if (test_bit(BRMR_SRV_STORE_OPEN, &dev->state)) + count += sysfs_emit_at(page, count, "open\n"); + else + count += sysfs_emit_at(page, count, "closed\n"); + + if (test_bit(BRMR_SRV_STORE_MAPPED, &dev->state)) + count += sysfs_emit_at(page, count, "mapped\n"); + else + count += sysfs_emit_at(page, count, "unmapped\n"); + + return count; +} + +static struct kobj_attribute blk_str_state_attr = + __ATTR_RO(state); + +static struct attribute *blk_str_map_attrs[] = { + &blk_str_dev_size_attr.attr, + &blk_str_mapped_size_attr.attr, + &blk_str_bdev_name_attr.attr, + &blk_str_remove_store_attr.attr, + &blk_str_delete_store_attr.attr, + &blk_str_state_attr.attr, + NULL, +}; +ATTRIBUTE_GROUPS(blk_str_map); + +static struct kobj_type blk_str_device_ktype = { + .sysfs_ops = &kobj_sysfs_ops, + .default_groups = blk_str_map_groups, +}; + +static int blk_str_create_sysfs_files(struct brmr_srv_blk_dev *dev) +{ + int ret; + + ret = kobject_init_and_add(&dev->kobj, &blk_str_device_ktype, + &rmr_strs_dev->kobj, + "%s", dev->poolname); + if (ret) + pr_err("Failed to create sysfs dir for store %s, name %s, err=%d\n", + dev->name, dev->poolname, ret); + + return ret; +} + +void blk_str_destroy_sysfs_files(struct brmr_srv_blk_dev *dev, + const struct attribute *sysfs_self) +{ + if (sysfs_self) + sysfs_remove_file_self(&dev->kobj, sysfs_self); + + kobject_del(&dev->kobj); + kobject_put(&dev->kobj); +} + +/** + * brmr_srv_blk_dev_exit() - Destroy and put the blkdev + * + * @dev: RMR block device structure to be used. + * + * Description: + * This function gives up the blkdev reference, and destroys the rmr block device + */ +static void brmr_srv_blk_dev_exit(struct brmr_srv_blk_dev *dev) +{ + pr_info("%s: put blkdev %s\n", __func__, dev->name); + bdev_fput(dev->bdev_file); + + brmr_srv_blk_destroy(dev); +} + +/** + * brmr_srv_blk_dev_init() - Create and initialize a brmr server store block device + * + * @pool_name: Name to be given to the created rmr block device + * @dev_name: path to the block device + * @mapped_size:mapped size of the block device + * + * Description: + * This function checks whether the rmr pool is available to be registered. + * It then creates the block device, and initializes it. + * + * Return: + * Pointer to the created rmr block device on success + * Error pointer on error + */ +static struct brmr_srv_blk_dev *brmr_srv_blk_dev_init(char *pool_name, char *dev_name, + u64 mapped_size) +{ + struct file *bdev_file; + struct brmr_srv_blk_dev *dev; + + dev = brmr_srv_blk_create(dev_name, pool_name); + if (IS_ERR(dev)) { + pr_err("failed to alloc store for device %s: %pe\n", pool_name, dev); + return dev; + } + + bdev_file = bdev_file_open_by_path(dev_name, DEFAULT_BLK_OPEN_FLAGS, + dev, NULL); + if (IS_ERR(bdev_file)) { + pr_err("%s: bdev_file_open_by_path for device %s failed with err (%pe)\n", + __func__, dev_name, bdev_file); + brmr_srv_blk_destroy(dev); + return ERR_CAST(bdev_file); + } + + dev->bdev_file = bdev_file; + dev->bdev = file_bdev(bdev_file); + dev->dev_size = get_capacity(dev->bdev->bd_disk); + strscpy(dev->name, dev->bdev->bd_disk->disk_name, sizeof(dev->name)); + + if (mapped_size < BLK_STR_MIN_MAPPED_SIZE) { + pr_err("%s: Given mapped size %llu less than minimum default(%lu) for dev %s\n", + __func__, mapped_size, BLK_STR_MIN_MAPPED_SIZE, dev->name); + brmr_srv_blk_dev_exit(dev); + return ERR_PTR(-ENOSPC); + } + + if (mapped_size + BLK_STR_MD_SIZE_SECTORS > dev->dev_size) { + pr_err("can not map %llu, only %llu available %s\n", + mapped_size, dev->dev_size - BLK_STR_MD_SIZE_SECTORS, dev->name); + brmr_srv_blk_dev_exit(dev); + return ERR_PTR(-ENOSPC); + } + + dev->mapped_size = mapped_size; + + pr_info("%s: succeeded\n", __func__); + + return dev; +} + +static ssize_t brmr_srv_create_store_store(struct kobject *kobj, + struct kobj_attribute *attr, + const char *buf, size_t count) +{ + struct brmr_srv_str_options opt; + char dev_name[NAME_MAX]; + char pool_name[NAME_MAX]; + struct brmr_srv_blk_dev *dev; + struct brmr_srv_blk_dev_meta *md_page; + int md_state, err; + + opt.pool = pool_name; + opt.device = dev_name; + opt.mapped_size = 0; + + if (brmr_srv_parse_add_opts(buf, &opt, NULL)) + goto out; + + md_page = kzalloc(PAGE_SIZE, GFP_KERNEL); + if (!md_page) { + pr_err("%s: Failed to allocate page to read md\n", __func__); + goto out; + } + + mutex_lock(&store_mutex); + + dev = brmr_srv_blk_dev_init(pool_name, dev_name, opt.mapped_size); + if (IS_ERR(dev)) { + pr_err("%s: brmr_srv_blk_dev_init failed: %pe\n", __func__, dev); + goto mut_unlock; + } + + md_state = brmr_srv_read_and_check_md(dev, md_page); + if (md_state != -1) { + /* + * read and check md failed. It could be read error or that md exists + */ + pr_err("%s: md read and check failed: %d\n", __func__, md_state); + goto dev_exit; + } + + err = brmr_srv_blk_open(dev, dev_name, true, false); + if (err) { + pr_err("failed to open %s, err %d\n", dev_name, err); + goto dev_exit; + } + + err = blk_str_create_sysfs_files(dev); + if (err) { + pr_err("failed to create sysfs files\n"); + goto dev_close; + } + + mutex_unlock(&store_mutex); + pr_info("Created new blk store for %s, with disk %s\n", pool_name, dev_name); + + kfree(md_page); + return count; + +dev_close: + brmr_srv_blk_close(dev, true); +dev_exit: + brmr_srv_blk_dev_exit(dev); +mut_unlock: + mutex_unlock(&store_mutex); + kfree(md_page); +out: + return -EINVAL; +} + +static ssize_t brmr_srv_create_store_show(struct kobject *kobj, + struct kobj_attribute *attr, + char *page) +{ + return scnprintf(page, PAGE_SIZE, + "Usage: echo \"pool= device= mapped_size=\" > %s\n\n", + attr->attr.name); +} + +static struct kobj_attribute brmr_srv_create_store_attr = + __ATTR(create_store, 0644, + brmr_srv_create_store_show, brmr_srv_create_store_store); + +static ssize_t brmr_srv_add_store_store(struct kobject *kobj, struct kobj_attribute *attr, + const char *buf, size_t count) +{ + struct brmr_srv_blk_dev *dev; + char dev_name[NAME_MAX]; + char pool_name[NAME_MAX]; + struct brmr_srv_str_options opt; + struct brmr_srv_blk_dev_meta *md_page; + int md_state, ret; + unsigned int replace = false; + + opt.pool = pool_name; + opt.device = dev_name; + opt.mapped_size = 0; + + if (brmr_srv_parse_add_opts(buf, &opt, &replace)) + goto out; + + /* + * Disable replace mode for now. + * Most of the code for replace mode to work is present, but there are some + * edge cases which needs work, and a info exchange between storage nodes which + * needs to be added. + */ + if (replace) { + pr_err("%s: Replace mode not supported yet\n", __func__); + goto out; + } + + md_page = kzalloc(PAGE_SIZE, GFP_KERNEL); + if (!md_page) { + pr_err("Failed to allocate page to read md\n"); + goto out; + } + + mutex_lock(&store_mutex); + + dev = brmr_srv_blk_dev_init(pool_name, dev_name, opt.mapped_size); + if (IS_ERR(dev)) { + pr_err("brmr_srv_blk_dev_init failed: %pe\n", dev); + goto mut_unlock; + } + + md_state = brmr_srv_read_and_check_md(dev, md_page); + if (md_state == -1) { + /* + * md doesn't exists. This means the disk is an empty one. + * We have to replace, so check the mode first + */ + if (!replace) { + pr_err("%s: Incorrect mode %d. md doesn't exists\n", __func__, replace); + goto dev_exit; + } + + /* + * we have to do the following, + * + * 1) Check params like mapped size from at least one other storage node + * 2) Do discard + */ + pr_info("%s: No md found. Replacing disk %s for pool %s, size %llu\n", + __func__, dev_name, pool_name, dev->mapped_size); + } else if (md_state == 0) { + /* + * md exists. + * We are restoring an earlier used device. + */ + if (replace) { + pr_err("%s: Incorrect mode %d. md exists\n", __func__, replace); + goto dev_exit; + } + + /* + * Validate the metadata stored with the data provided. + */ + ret = brmr_srv_blk_validate_md(dev, md_page); + if (ret) { + pr_err("Local metadata validation failed\n"); + goto dev_exit; + } + + memcpy(&dev->dev_params, &md_page->dev_params, sizeof(struct rmr_blk_dev_params)); + dev->state = md_page->state; + + pr_info("%s: md found. Re-adding disk %s for pool %s, size %llu\n", + __func__, dev_name, pool_name, dev->mapped_size); + } else { + pr_err("%s: md cannot be read for block device %s, Err = %d\n", + __func__, dev->name, md_state); + goto dev_exit; + } + + if (brmr_srv_blk_open(dev, dev_name, false /* create */, replace)) { + pr_err("failed to open %s\n", dev_name); + goto dev_exit; + } + + ret = blk_str_create_sysfs_files(dev); + if (ret) { + pr_err("failed to create sysfs files\n"); + goto dev_close; + } + + mutex_unlock(&store_mutex); + + kfree(md_page); + return count; + +dev_close: + brmr_srv_blk_close(dev, replace); +dev_exit: + brmr_srv_blk_dev_exit(dev); +mut_unlock: + mutex_unlock(&store_mutex); + kfree(md_page); +out: + return -EINVAL; +} + +static ssize_t brmr_srv_add_store_show(struct kobject *kobj, + struct kobj_attribute *attr, + char *page) +{ + return scnprintf(page, PAGE_SIZE, + "Usage: echo \"pool= device= mapped_size=\" > %s\n\n", + attr->attr.name); +} + +static struct kobj_attribute brmr_srv_add_store_attr = + __ATTR(add_store, 0644, + brmr_srv_add_store_show, brmr_srv_add_store_store); + +static struct attribute *default_attrs[] = { + &brmr_srv_create_store_attr.attr, + &brmr_srv_add_store_attr.attr, + NULL, +}; + +static struct attribute_group default_attr_group = { + .attrs = default_attrs, +}; + +int brmr_srv_create_sysfs_files(void) +{ + int err; + dev_t devt = MKDEV(0, 0); + + rmr_str_class = class_create("brmr-server"); + if (IS_ERR(rmr_str_class)) + return PTR_ERR(rmr_str_class); + + rmr_ctl_dev = device_create(rmr_str_class, NULL, devt, NULL, "ctl"); + if (IS_ERR(rmr_ctl_dev)) { + err = PTR_ERR(rmr_ctl_dev); + goto cls_destroy; + } + + rmr_strs_dev = device_create(rmr_str_class, NULL, devt, NULL, "stores"); + if (IS_ERR(rmr_strs_dev)) { + err = PTR_ERR(rmr_strs_dev); + goto ctl_destroy; + } + + err = sysfs_create_group(&rmr_ctl_dev->kobj, &default_attr_group); + if (unlikely(err)) + goto strs_destroy; + + return 0; + +strs_destroy: + device_unregister(rmr_strs_dev); +ctl_destroy: + device_unregister(rmr_ctl_dev); +cls_destroy: + class_destroy(rmr_str_class); + + return err; +} + +void brmr_srv_destroy_sysfs_files(void) +{ + sysfs_remove_group(&rmr_ctl_dev->kobj, &default_attr_group); + device_unregister(rmr_strs_dev); + device_unregister(rmr_ctl_dev); + class_destroy(rmr_str_class); +} -- 2.43.0