exofs: Add SYSFS info for autologin/pNFS export

Introduce sysfs infrastructure for exofs cluster filesystem.

Each OSD target shows up as below in the sysfs hierarchy:
	/sys/fs/exofs/<osdname>_<partition_id>/devX

Where <osdname>_<partition_id> is the unique identification
of a Superblock.

Where devX: 0 <= X < device_table_size. They are ordered
in device-table order as specified to the mkfs.exofs command

Each OSD device  devX has following attributes :
	osdname - ReadOnly
	systemid - ReadOnly
	uri - Read/Write

It is up to user-mode to update devX/uri for support of
autologin.

These sysfs information are used both for autologin as well
as support for exporting exofs via a pNFSD server in user-mode.
(.eg NFS-Ganesha)
Signed-off-by: Sachin Bhamare <sbhamare@panasas.com>
Signed-off-by: Boaz Harrosh <bharrosh@panasas.com>

fs/exofs/Kbuild

@@ -16,5 +16,5 @@
 libore-y := ore.o ore_raid.o
 obj-$(CONFIG_ORE) += libore.o
 
-exofs-y := inode.o file.o symlink.o namei.o dir.o super.o
+exofs-y := inode.o file.o symlink.o namei.o dir.o super.o sys.o
 obj-$(CONFIG_EXOFS_FS) += exofs.o

fs/exofs/exofs.h

@@ -56,6 +56,9 @@
 struct exofs_dev {
 	struct ore_dev ored;
 	unsigned did;
+	unsigned urilen;
+	uint8_t *uri;
+	struct kobject ed_kobj;
 };
 /*
  * our extension to the in-memory superblock
@@ -73,6 +76,7 @@ struct exofs_sb_info {
 	struct ore_layout	layout;		/* Default files layout       */
 	struct ore_comp one_comp;		/* id & cred of partition id=0*/
 	struct ore_components oc;		/* comps for the partition    */
+	struct kobject	s_kobj;			/* holds per-sbi kobject      */
 };
 
 /*
@@ -176,6 +180,16 @@ void exofs_make_credential(u8 cred_a[OSD_CAP_LEN],
 			   const struct osd_obj_id *obj);
 int exofs_sbi_write_stats(struct exofs_sb_info *sbi);
 
+/* sys.c                 */
+int exofs_sysfs_init(void);
+void exofs_sysfs_uninit(void);
+int exofs_sysfs_sb_add(struct exofs_sb_info *sbi,
+		       struct exofs_dt_device_info *dt_dev);
+void exofs_sysfs_sb_del(struct exofs_sb_info *sbi);
+int exofs_sysfs_odev_add(struct exofs_dev *edev,
+			 struct exofs_sb_info *sbi);
+void exofs_sysfs_dbg_print(void);
+
 /*********************
  * operation vectors *
  *********************/

fs/exofs/super.c

@@ -472,6 +472,7 @@ static void exofs_put_super(struct super_block *sb)
 	_exofs_print_device("Unmounting", NULL, ore_comp_dev(&sbi->oc, 0),
 			    sbi->one_comp.obj.partition);
 
+	exofs_sysfs_sb_del(sbi);
 	bdi_destroy(&sbi->bdi);
 	exofs_free_sbi(sbi);
 	sb->s_fs_info = NULL;
@@ -632,6 +633,12 @@ static int exofs_read_lookup_dev_table(struct exofs_sb_info *sbi,
 	memcpy(&sbi->oc.ods[numdevs], &sbi->oc.ods[0],
 		(numdevs - 1) * sizeof(sbi->oc.ods[0]));
 
+	/* create sysfs subdir under which we put the device table
+	 * And cluster layout. A Superblock is identified by the string:
+	 *	"dev[0].osdname"_"pid"
+	 */
+	exofs_sysfs_sb_add(sbi, &dt->dt_dev_table[0]);
+
 	for (i = 0; i < numdevs; i++) {
 		struct exofs_fscb fscb;
 		struct osd_dev_info odi;
@@ -657,6 +664,7 @@ static int exofs_read_lookup_dev_table(struct exofs_sb_info *sbi,
 			eds[i].ored.od = fscb_od;
 			++sbi->oc.numdevs;
 			fscb_od = NULL;
+			exofs_sysfs_odev_add(&eds[i], sbi);
 			continue;
 		}
 
@@ -682,6 +690,7 @@ static int exofs_read_lookup_dev_table(struct exofs_sb_info *sbi,
 				  odi.osdname);
 			goto out;
 		}
+		exofs_sysfs_odev_add(&eds[i], sbi);
 
 		/* TODO: verify other information is correct and FS-uuid
 		 *	 matches. Benny what did you say about device table
@@ -844,6 +853,7 @@ static int exofs_fill_super(struct super_block *sb, void *data, int silent)
 		goto free_sbi;
 	}
 
+	exofs_sysfs_dbg_print();
 	_exofs_print_device("Mounting", opts->dev_name,
 			    ore_comp_dev(&sbi->oc, 0),
 			    sbi->one_comp.obj.partition);
@@ -1023,6 +1033,9 @@ static int __init init_exofs(void)
 	if (err)
 		goto out_d;
 
+	/* We don't fail if sysfs creation failed */
+	exofs_sysfs_init();
+
 	return 0;
 out_d:
 	destroy_inodecache();
@@ -1032,6 +1045,7 @@ static int __init init_exofs(void)
 
 static void __exit exit_exofs(void)
 {
+	exofs_sysfs_uninit();
 	unregister_filesystem(&exofs_type);
 	destroy_inodecache();
 }

fs/exofs/sys.c

+/*
+ * Copyright (C) 2012
+ * Sachin Bhamare <sbhamare@panasas.com>
+ * Boaz Harrosh <bharrosh@panasas.com>
+ *
+ * This file is part of exofs.
+ *
+ * exofs is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License 2 as published by
+ * the Free Software Foundation.
+ *
+ * exofs is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with exofs; if not, write to the:
+ *	Free Software Foundation <licensing@fsf.org>
+ */
+
+#include <linux/kobject.h>
+#include <linux/device.h>
+
+#include "exofs.h"
+
+struct odev_attr {
+	struct attribute attr;
+	ssize_t (*show)(struct exofs_dev *, char *);
+	ssize_t (*store)(struct exofs_dev *, const char *, size_t);
+};
+
+static ssize_t odev_attr_show(struct kobject *kobj, struct attribute *attr,
+		char *buf)
+{
+	struct exofs_dev *edp = container_of(kobj, struct exofs_dev, ed_kobj);
+	struct odev_attr *a = container_of(attr, struct odev_attr, attr);
+
+	return a->show ? a->show(edp, buf) : 0;
+}
+
+static ssize_t odev_attr_store(struct kobject *kobj, struct attribute *attr,
+		const char *buf, size_t len)
+{
+	struct exofs_dev *edp = container_of(kobj, struct exofs_dev, ed_kobj);
+	struct odev_attr *a = container_of(attr, struct odev_attr, attr);
+
+	return a->store ? a->store(edp, buf, len) : len;
+}
+
+static const struct sysfs_ops odev_attr_ops = {
+	.show  = odev_attr_show,
+	.store = odev_attr_store,
+};
+
+
+static struct kset *exofs_kset;
+
+static ssize_t osdname_show(struct exofs_dev *edp, char *buf)
+{
+	struct osd_dev *odev = edp->ored.od;
+	const struct osd_dev_info *odi = osduld_device_info(odev);
+
+	return snprintf(buf, odi->osdname_len + 1, "%s", odi->osdname);
+}
+
+static ssize_t systemid_show(struct exofs_dev *edp, char *buf)
+{
+	struct osd_dev *odev = edp->ored.od;
+	const struct osd_dev_info *odi = osduld_device_info(odev);
+
+	memcpy(buf, odi->systemid, odi->systemid_len);
+	return odi->systemid_len;
+}
+
+static ssize_t uri_show(struct exofs_dev *edp, char *buf)
+{
+	return snprintf(buf, edp->urilen, "%s", edp->uri);
+}
+
+static ssize_t uri_store(struct exofs_dev *edp, const char *buf, size_t len)
+{
+	edp->urilen = strlen(buf) + 1;
+	edp->uri = krealloc(edp->uri, edp->urilen, GFP_KERNEL);
+	strncpy(edp->uri, buf, edp->urilen);
+	return edp->urilen;
+}
+
+#define OSD_ATTR(name, mode, show, store) \
+	static struct odev_attr odev_attr_##name = \
+					__ATTR(name, mode, show, store)
+
+OSD_ATTR(osdname, S_IRUGO, osdname_show, NULL);
+OSD_ATTR(systemid, S_IRUGO, systemid_show, NULL);
+OSD_ATTR(uri, S_IRWXU, uri_show, uri_store);
+
+static struct attribute *odev_attrs[] = {
+	&odev_attr_osdname.attr,
+	&odev_attr_systemid.attr,
+	&odev_attr_uri.attr,
+	NULL,
+};
+
+static struct kobj_type odev_ktype = {
+	.default_attrs	= odev_attrs,
+	.sysfs_ops	= &odev_attr_ops,
+};
+
+static struct kobj_type uuid_ktype = {
+};
+
+void exofs_sysfs_dbg_print()
+{
+#ifdef CONFIG_EXOFS_DEBUG
+	struct kobject *k_name, *k_tmp;
+
+	list_for_each_entry_safe(k_name, k_tmp, &exofs_kset->list, entry) {
+		printk(KERN_INFO "%s: name %s ref %d\n",
+			__func__, kobject_name(k_name),
+			(int)atomic_read(&k_name->kref.refcount));
+	}
+#endif
+}
+/*
+ * This function removes all kobjects under exofs_kset
+ * At the end of it, exofs_kset kobject will have a refcount
+ * of 1 which gets decremented only on exofs module unload
+ */
+void exofs_sysfs_sb_del(struct exofs_sb_info *sbi)
+{
+	struct kobject *k_name, *k_tmp;
+	struct kobject *s_kobj = &sbi->s_kobj;
+
+	list_for_each_entry_safe(k_name, k_tmp, &exofs_kset->list, entry) {
+		/* Remove all that are children of this SBI */
+		if (k_name->parent == s_kobj)
+			kobject_put(k_name);
+	}
+	kobject_put(s_kobj);
+}
+
+/*
+ * This function creates sysfs entries to hold the current exofs cluster
+ * instance (uniquely identified by osdname,pid tuple).
+ * This function gets called once per exofs mount instance.
+ */
+int exofs_sysfs_sb_add(struct exofs_sb_info *sbi,
+		       struct exofs_dt_device_info *dt_dev)
+{
+	struct kobject *s_kobj;
+	int retval = 0;
+	uint64_t pid = sbi->one_comp.obj.partition;
+
+	/* allocate new uuid dirent */
+	s_kobj = &sbi->s_kobj;
+	s_kobj->kset = exofs_kset;
+	retval = kobject_init_and_add(s_kobj, &uuid_ktype,
+			&exofs_kset->kobj,  "%s_%llx", dt_dev->osdname, pid);
+	if (retval) {
+		EXOFS_ERR("ERROR: Failed to create sysfs entry for "
+			  "uuid-%s_%llx => %d\n", dt_dev->osdname, pid, retval);
+		return -ENOMEM;
+	}
+	return 0;
+}
+
+int exofs_sysfs_odev_add(struct exofs_dev *edev, struct exofs_sb_info *sbi)
+{
+	struct kobject *d_kobj;
+	int retval = 0;
+
+	/* create osd device group which contains following attributes
+	 * osdname, systemid & uri
+	 */
+	d_kobj = &edev->ed_kobj;
+	d_kobj->kset = exofs_kset;
+	retval = kobject_init_and_add(d_kobj, &odev_ktype,
+			&sbi->s_kobj, "dev%u", edev->did);
+	if (retval) {
+		EXOFS_ERR("ERROR: Failed to create sysfs entry for "
+				"device dev%u\n", edev->did);
+		return retval;
+	}
+	return 0;
+}
+
+int exofs_sysfs_init(void)
+{
+	exofs_kset = kset_create_and_add("exofs", NULL, fs_kobj);
+	if (!exofs_kset) {
+		EXOFS_ERR("ERROR: kset_create_and_add exofs failed\n");
+		return -ENOMEM;
+	}
+	return 0;
+}
+
+void exofs_sysfs_uninit(void)
+{
+	kset_unregister(exofs_kset);
+}