This patch provides common functions to create symlinks in sysfs
between stacked device and its slaves.
I placed functions in fs/block_dev.c as some of them are
privately used by bd_claim().
I'm not sure if it's better to put them in other files.
--
Jun'ichi Nomura, NEC Solutions (America), Inc.
Exporting stacked device relationship to sysfs (common functions)
Signed-off-by: Jun'ichi Nomura <[email protected]>
--- linux-2.6.15.orig/include/linux/fs.h 2006-01-02 22:21:10.000000000 -0500
+++ linux-2.6.15/include/linux/fs.h 2006-02-16 10:46:31.000000000 -0500
@@ -373,6 +373,7 @@ struct block_device {
struct list_head bd_inodes;
void * bd_holder;
int bd_holders;
+ struct kobject bd_holder_kobj;
struct block_device * bd_contains;
unsigned bd_block_size;
struct hd_struct * bd_part;
@@ -1352,6 +1353,13 @@ extern int blkdev_put(struct block_devic
extern int bd_claim(struct block_device *, void *);
extern void bd_release(struct block_device *);
+/* stacked device linking */
+extern void stackdev_init(struct kobject *, struct kobject *);
+extern void stackdev_clear(struct kobject *);
+extern void stackdev_link(struct block_device *,
+ struct kobject *, struct kobject *);
+extern void stackdev_unlink(struct block_device *,
+ struct kobject *, struct kobject *);
/* fs/char_dev.c */
extern int alloc_chrdev_region(dev_t *, unsigned, unsigned, const char *);
extern int register_chrdev_region(dev_t, unsigned, const char *);
--- linux-2.6.15.orig/fs/block_dev.c 2006-01-02 22:21:10.000000000 -0500
+++ linux-2.6.15/fs/block_dev.c 2006-02-17 10:06:17.000000000 -0500
@@ -443,6 +443,126 @@ void bd_forget(struct inode *inode)
spin_unlock(&bdev_lock);
}
+/*
+ * kobject linking functions for stacked device
+ */
+
+static inline struct kobject * bdev_get_kobj(struct block_device *bdev)
+{
+ if (!bdev)
+ return NULL;
+ else if (bdev->bd_contains != bdev)
+ return kobject_get(&bdev->bd_part->kobj);
+ else
+ return kobject_get(&bdev->bd_disk->kobj);
+}
+
+static inline void add_symlink(struct kobject *from, struct kobject *to)
+{
+ if (!from || !to)
+ return;
+ sysfs_create_link(from, to, kobject_name(to));
+}
+
+static inline void del_symlink(struct kobject *from, struct kobject *to)
+{
+ if (!from || !to)
+ return;
+ sysfs_remove_link(from, kobject_name(to));
+}
+
+/* This is a mere directory in sysfs. No methods are needed. */
+static struct kobj_type bd_holder_ktype = {
+ .release = NULL,
+ .sysfs_ops = NULL,
+ .default_attrs = NULL,
+};
+
+/*
+ * Set the bdev as possible slave of a stacked device
+ * (called from bd_claim)
+ */
+static inline void add_holder_object(struct block_device *bdev)
+{
+ struct kobject *kobj = &bdev->bd_holder_kobj;
+
+ kobj->ktype = &bd_holder_ktype;
+ kobject_set_name(kobj, "holders");
+ kobj->parent = bdev_get_kobj(bdev);
+ kobject_register(kobj);
+ kobject_put(kobj->parent);
+}
+
+/*
+ * Declare the bdev is no longer a possible slave of a stacked device
+ * (called from bd_release)
+ */
+static inline void del_holder_object(struct block_device *bdev)
+{
+ kobject_unregister(&bdev->bd_holder_kobj);
+}
+
+/* This is a mere directory in sysfs. No methods are needed. */
+static struct kobj_type bd_slave_ktype = {
+ .release = NULL,
+ .sysfs_ops = NULL,
+ .default_attrs = NULL,
+};
+
+/* Set the bdev as stacked device */
+void stackdev_init(struct kobject *slave_dir, struct kobject *holder_dev)
+{
+ slave_dir->ktype = &bd_slave_ktype;
+ kobject_set_name(slave_dir, "slaves");
+ slave_dir->parent = holder_dev;
+
+ kobject_register(slave_dir);
+}
+EXPORT_SYMBOL(stackdev_init);
+
+/* Declare the bdev is no longer a stacked device */
+void stackdev_clear(struct kobject *slave_dir)
+{
+ kobject_unregister(slave_dir);
+}
+EXPORT_SYMBOL(stackdev_clear);
+
+/*
+ * Create symlinks between the holder and the slave of the stacked device.
+ * The slave devices needs to be bd_claim()-ed before.
+ */
+void stackdev_link(struct block_device *slave,
+ struct kobject *slave_dir, struct kobject *holder_dev)
+{
+ struct kobject *slave_dev, *holder_dir;
+
+ slave_dev = bdev_get_kobj(slave);
+
+ add_symlink(slave_dir, slave_dev);
+ add_symlink(&slave->bd_holder_kobj, holder_dev);
+
+ kobject_put(slave_dev);
+}
+EXPORT_SYMBOL(stackdev_link);
+
+/*
+ * Remove symlinks between the holder and the slave of the stacked device.
+ * This should be called before bd_release() the slave device.
+ */
+void stackdev_unlink(struct block_device *slave,
+ struct kobject *slave_dir, struct kobject *holder_dev)
+{
+ struct kobject *slave_dev, *holder_dir;
+
+ slave_dev = bdev_get_kobj(slave);
+
+ del_symlink(slave_dir, slave_dev);
+ del_symlink(&slave->bd_holder_kobj, holder_dev);
+
+ kobject_put(slave_dev);
+}
+EXPORT_SYMBOL(stackdev_unlink);
+
int bd_claim(struct block_device *bdev, void *holder)
{
int res;
@@ -450,7 +570,7 @@ int bd_claim(struct block_device *bdev,
/* first decide result */
if (bdev->bd_holder == holder)
- res = 0; /* already a holder */
+ res = 1; /* already a holder */
else if (bdev->bd_holder != NULL)
res = -EBUSY; /* held by someone else */
else if (bdev->bd_contains == bdev)
@@ -469,10 +589,14 @@ int bd_claim(struct block_device *bdev,
* will be incremented twice, and bd_holder will
* be set to bd_claim before being set to holder
*/
- bdev->bd_contains->bd_holders ++;
bdev->bd_contains->bd_holder = bd_claim;
- bdev->bd_holders++;
bdev->bd_holder = holder;
+ add_holder_object(bdev);
+ }
+ if (res >= 0) {
+ bdev->bd_contains->bd_holders ++;
+ bdev->bd_holders++;
+ res = 0;
}
spin_unlock(&bdev_lock);
return res;
@@ -485,8 +609,10 @@ void bd_release(struct block_device *bde
spin_lock(&bdev_lock);
if (!--bdev->bd_contains->bd_holders)
bdev->bd_contains->bd_holder = NULL;
- if (!--bdev->bd_holders)
+ if (!--bdev->bd_holders) {
bdev->bd_holder = NULL;
+ del_holder_object(bdev);
+ }
spin_unlock(&bdev_lock);
}
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