From 784aae735d9b0bba3f8b9faef4c8b30df3bf0128 Mon Sep 17 00:00:00 2001 From: Milan Broz Date: Tue, 6 Jan 2009 03:05:12 +0000 Subject: [PATCH] dm: add name and uuid to sysfs Implement simple read-only sysfs entry for device-mapper block device. This patch adds a simple sysfs directory named "dm" under block device properties and implements - name attribute (string containing mapped device name) - uuid attribute (string containing UUID, or empty string if not set) The kobject is embedded in mapped_device struct, so no additional memory allocation is needed for initializing sysfs entry. During the processing of sysfs attribute we need to lock mapped device which is done by a new function dm_get_from_kobj, which returns the md associated with kobject and increases the usage count. Each 'show attribute' function is responsible for its own locking. Signed-off-by: Milan Broz Signed-off-by: Alasdair G Kergon --- drivers/md/Makefile | 2 +- drivers/md/dm-sysfs.c | 99 +++++++++++++++++++++++++++++++++++++++++++ drivers/md/dm.c | 29 ++++++++++++- drivers/md/dm.h | 8 ++++ 4 files changed, 136 insertions(+), 2 deletions(-) create mode 100644 drivers/md/dm-sysfs.c diff --git a/drivers/md/Makefile b/drivers/md/Makefile index 1c615804ea76..63f0ae94415d 100644 --- a/drivers/md/Makefile +++ b/drivers/md/Makefile @@ -3,7 +3,7 @@ # dm-mod-objs := dm.o dm-table.o dm-target.o dm-linear.o dm-stripe.o \ - dm-ioctl.o dm-io.o dm-kcopyd.o + dm-ioctl.o dm-io.o dm-kcopyd.o dm-sysfs.o dm-multipath-objs := dm-path-selector.o dm-mpath.o dm-snapshot-objs := dm-snap.o dm-exception-store.o dm-mirror-objs := dm-raid1.o diff --git a/drivers/md/dm-sysfs.c b/drivers/md/dm-sysfs.c new file mode 100644 index 000000000000..a2a45e6c7c8b --- /dev/null +++ b/drivers/md/dm-sysfs.c @@ -0,0 +1,99 @@ +/* + * Copyright (C) 2008 Red Hat, Inc. All rights reserved. + * + * This file is released under the GPL. + */ + +#include +#include +#include "dm.h" + +struct dm_sysfs_attr { + struct attribute attr; + ssize_t (*show)(struct mapped_device *, char *); + ssize_t (*store)(struct mapped_device *, char *); +}; + +#define DM_ATTR_RO(_name) \ +struct dm_sysfs_attr dm_attr_##_name = \ + __ATTR(_name, S_IRUGO, dm_attr_##_name##_show, NULL) + +static ssize_t dm_attr_show(struct kobject *kobj, struct attribute *attr, + char *page) +{ + struct dm_sysfs_attr *dm_attr; + struct mapped_device *md; + ssize_t ret; + + dm_attr = container_of(attr, struct dm_sysfs_attr, attr); + if (!dm_attr->show) + return -EIO; + + md = dm_get_from_kobject(kobj); + if (!md) + return -EINVAL; + + ret = dm_attr->show(md, page); + dm_put(md); + + return ret; +} + +static ssize_t dm_attr_name_show(struct mapped_device *md, char *buf) +{ + if (dm_copy_name_and_uuid(md, buf, NULL)) + return -EIO; + + strcat(buf, "\n"); + return strlen(buf); +} + +static ssize_t dm_attr_uuid_show(struct mapped_device *md, char *buf) +{ + if (dm_copy_name_and_uuid(md, NULL, buf)) + return -EIO; + + strcat(buf, "\n"); + return strlen(buf); +} + +static DM_ATTR_RO(name); +static DM_ATTR_RO(uuid); + +static struct attribute *dm_attrs[] = { + &dm_attr_name.attr, + &dm_attr_uuid.attr, + NULL, +}; + +static struct sysfs_ops dm_sysfs_ops = { + .show = dm_attr_show, +}; + +/* + * dm kobject is embedded in mapped_device structure + * no need to define release function here + */ +static struct kobj_type dm_ktype = { + .sysfs_ops = &dm_sysfs_ops, + .default_attrs = dm_attrs, +}; + +/* + * Initialize kobj + * because nobody using md yet, no need to call explicit dm_get/put + */ +int dm_sysfs_init(struct mapped_device *md) +{ + return kobject_init_and_add(dm_kobject(md), &dm_ktype, + &disk_to_dev(dm_disk(md))->kobj, + "%s", "dm"); +} + +/* + * Remove kobj, called after all references removed + */ +void dm_sysfs_exit(struct mapped_device *md) +{ + kobject_put(dm_kobject(md)); +} diff --git a/drivers/md/dm.c b/drivers/md/dm.c index 9f9aa64f7336..51ba1db4b3e7 100644 --- a/drivers/md/dm.c +++ b/drivers/md/dm.c @@ -1,6 +1,6 @@ /* * Copyright (C) 2001, 2002 Sistina Software (UK) Limited. - * Copyright (C) 2004-2006 Red Hat, Inc. All rights reserved. + * Copyright (C) 2004-2008 Red Hat, Inc. All rights reserved. * * This file is released under the GPL. */ @@ -167,6 +167,9 @@ struct mapped_device { /* forced geometry settings */ struct hd_geometry geometry; + + /* sysfs handle */ + struct kobject kobj; }; #define MIN_IOS 256 @@ -1285,6 +1288,8 @@ int dm_create(int minor, struct mapped_device **result) if (!md) return -ENXIO; + dm_sysfs_init(md); + *result = md; return 0; } @@ -1360,6 +1365,7 @@ void dm_put(struct mapped_device *md) dm_table_presuspend_targets(map); dm_table_postsuspend_targets(map); } + dm_sysfs_exit(md); dm_table_put(map); __unbind(md); free_dev(md); @@ -1699,6 +1705,27 @@ struct gendisk *dm_disk(struct mapped_device *md) return md->disk; } +struct kobject *dm_kobject(struct mapped_device *md) +{ + return &md->kobj; +} + +/* + * struct mapped_device should not be exported outside of dm.c + * so use this check to verify that kobj is part of md structure + */ +struct mapped_device *dm_get_from_kobject(struct kobject *kobj) +{ + struct mapped_device *md; + + md = container_of(kobj, struct mapped_device, kobj); + if (&md->kobj != kobj) + return NULL; + + dm_get(md); + return md; +} + int dm_suspended(struct mapped_device *md) { return test_bit(DMF_SUSPENDED, &md->flags); diff --git a/drivers/md/dm.h b/drivers/md/dm.h index bbbe9110f3bf..20194e000c5a 100644 --- a/drivers/md/dm.h +++ b/drivers/md/dm.h @@ -73,6 +73,14 @@ int dm_split_args(int *argc, char ***argvp, char *input); int dm_interface_init(void); void dm_interface_exit(void); +/* + * sysfs interface + */ +int dm_sysfs_init(struct mapped_device *md); +void dm_sysfs_exit(struct mapped_device *md); +struct kobject *dm_kobject(struct mapped_device *md); +struct mapped_device *dm_get_from_kobject(struct kobject *kobj); + /* * Targets for linear and striped mappings */ -- 2.39.2