This patch is part of dm/md dependency tree in sysfs.
This adds bd_claim_by_kobject() function which takes kobject as
additional signature of holder device and creates sysfs symlinks
between holder device and claimed device.
bd_release_from_kobject() is a counter part of bd_claim_by_kobject.
Thanks,
--
Jun'ichi Nomura, NEC Solutions (America), Inc.
Adding bd_claim_by_kobject() function which takes kobject as
additional signature of holder device and creates sysfs symlinks
between holder device and claimed device.
bd_release_from_kobject() is a counter part of bd_claim_by_kobject.
Signed-off-by: Jun'ichi Nomura <[email protected]>
fs/block_dev.c | 206 ++++++++++++++++++++++++++++++++++++++++++++++++++++
include/linux/fs.h | 3
2 files changed, 209 insertions(+)
--- linux-2.6.16-rc6.orig/include/linux/fs.h 2006-03-11 17:12:55.000000000 -0500
+++ linux-2.6.16-rc6/include/linux/fs.h 2006-03-13 11:24:18.000000000 -0500
@@ -402,6 +402,7 @@ struct block_device {
struct list_head bd_inodes;
void * bd_holder;
int bd_holders;
+ struct list_head bd_holder_list;
struct block_device * bd_contains;
unsigned bd_block_size;
struct hd_struct * bd_part;
@@ -1381,6 +1382,8 @@ extern int blkdev_get(struct block_devic
extern int blkdev_put(struct block_device *);
extern int bd_claim(struct block_device *, void *);
extern void bd_release(struct block_device *);
+extern int bd_claim_by_kobject(struct block_device *, void *, struct kobject *);
+extern void bd_release_from_kobject(struct block_device *, struct kobject *);
/* fs/char_dev.c */
extern int alloc_chrdev_region(dev_t *, unsigned, unsigned, const char *);
--- linux-2.6.16-rc6.orig/fs/block_dev.c 2006-03-11 17:12:55.000000000 -0500
+++ linux-2.6.16-rc6/fs/block_dev.c 2006-03-13 11:24:18.000000000 -0500
@@ -269,6 +269,7 @@ static void init_once(void * foo, kmem_c
sema_init(&bdev->bd_mount_sem, 1);
INIT_LIST_HEAD(&bdev->bd_inodes);
INIT_LIST_HEAD(&bdev->bd_list);
+ INIT_LIST_HEAD(&bdev->bd_holder_list);
inode_init_once(&ei->vfs_inode);
}
}
@@ -493,6 +494,211 @@ void bd_release(struct block_device *bde
EXPORT_SYMBOL(bd_release);
/*
+ * Functions for bd_claim_by_kobject / bd_release_from_kobject
+ *
+ * If a kobject is passed to bd_claim_by_kobject()
+ * and the kobject has a parent directory,
+ * following symlinks are created:
+ * o from the kobject to the claimed bdev
+ * o from "holders" directory of the bdev to the parent of the kobject
+ * bd_release_from_kobject() removes these symlinks.
+ *
+ * Example:
+ * If /dev/dm-0 maps to /dev/sda, kobject corresponding to
+ * /sys/block/dm-0/slaves is passed to bd_claim_by_kobject(), then:
+ * /sys/block/dm-0/slaves/sda --> /sys/block/sda
+ * /sys/block/sda/holders/dm-0 --> /sys/block/dm-0
+ */
+
+
+static inline struct kobject * bdev_get_kobj(struct block_device *bdev)
+{
+ if (bdev->bd_contains != bdev)
+ return kobject_get(&bdev->bd_part->kobj);
+ else
+ return kobject_get(&bdev->bd_disk->kobj);
+}
+
+static inline struct kobject * bdev_get_holder(struct block_device *bdev)
+{
+ if (bdev->bd_contains != bdev)
+ return kobject_get(bdev->bd_part->holder_dir);
+ else
+ return kobject_get(bdev->bd_disk->holder_dir);
+}
+
+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));
+}
+
+/* bd_holder_list is protected by bdev_lock */
+struct bd_holder {
+ struct list_head list; /* chain of holders of the bdev */
+ int count; /* references from the holder */
+ struct kobject *sdir; /* holder object, e.g. "/block/dm-0/slaves" */
+ struct kobject *hdev; /* e.g. "/block/dm-0" */
+ struct kobject *hdir; /* e.g. "/block/sda/holders" */
+ struct kobject *sdev; /* e.g. "/block/sda" */
+};
+
+static inline int bd_holder_grab_dirs(struct block_device *bdev,
+ struct bd_holder *bo)
+{
+ if (!bdev || !bo)
+ return 0;
+
+ bo->sdir = kobject_get(bo->sdir);
+ if (!bo->sdir)
+ return 0;
+
+ bo->hdev = kobject_get(bo->sdir->parent);
+ if (!bo->hdev)
+ goto fail_put_sdir;
+
+ bo->sdev = bdev_get_kobj(bdev);
+ if (!bo->sdev)
+ goto fail_put_hdev;
+
+ bo->hdir = bdev_get_holder(bdev);
+ if (!bo->hdir)
+ goto fail_put_sdev;
+
+ return 1;
+
+fail_put_sdev:
+ kobject_put(bo->sdev);
+fail_put_hdev:
+ kobject_put(bo->hdev);
+fail_put_sdir:
+ kobject_put(bo->sdir);
+
+ return 0;
+}
+
+static inline void bd_holder_release_dirs(struct bd_holder *bo)
+{
+ kobject_put(bo->hdir);
+ kobject_put(bo->sdev);
+ kobject_put(bo->hdev);
+ kobject_put(bo->sdir);
+}
+
+static struct bd_holder *alloc_bd_holder(struct kobject *kobj)
+{
+ struct bd_holder *bo;
+
+ bo = kzalloc(sizeof(*bo), GFP_KERNEL);
+ if (!bo)
+ return NULL;
+
+ bo->count = 1;
+ bo->sdir = kobj;
+
+ return bo;
+}
+
+static void free_bd_holder(struct bd_holder *bo)
+{
+ kfree(bo);
+}
+
+static int add_bd_holder(struct block_device *bdev, struct bd_holder *bo)
+{
+ struct bd_holder *tmp;
+
+ if (!bo)
+ return 0;
+
+ list_for_each_entry(tmp, &bdev->bd_holder_list, list) {
+ if (tmp->sdir == bo->sdir) {
+ tmp->count++;
+ return 0;
+ }
+ }
+
+ if (!bd_holder_grab_dirs(bdev, bo))
+ return 0;
+
+ add_symlink(bo->sdir, bo->sdev);
+ add_symlink(bo->hdir, bo->hdev);
+ list_add_tail(&bo->list, &bdev->bd_holder_list);
+ return 1;
+}
+
+static struct bd_holder *del_bd_holder(struct block_device *bdev,
+ struct kobject *kobj)
+{
+ struct bd_holder *bo;
+
+ list_for_each_entry(bo, &bdev->bd_holder_list, list) {
+ if (bo->sdir == kobj) {
+ bo->count--;
+ BUG_ON(bo->count < 0);
+ if (!bo->count) {
+ list_del(&bo->list);
+ del_symlink(bo->sdir, bo->sdev);
+ del_symlink(bo->hdir, bo->hdev);
+ bd_holder_release_dirs(bo);
+ return bo;
+ }
+ break;
+ }
+ }
+
+ return NULL;
+}
+
+int bd_claim_by_kobject(struct block_device *bdev, void *holder,
+ struct kobject *kobj)
+{
+ int res = -EBUSY;
+ struct bd_holder *bo;
+
+ if (!kobj)
+ return -EINVAL;
+
+ bo = alloc_bd_holder(kobj);
+ if (!bo)
+ return -ENOMEM;
+
+ down(&bdev->bd_sem);
+ res = bd_claim(bdev, holder);
+ if (res || !add_bd_holder(bdev, bo))
+ free_bd_holder(bo);
+ up(&bdev->bd_sem);
+
+ return res;
+}
+
+EXPORT_SYMBOL(bd_claim_by_kobject);
+
+void bd_release_from_kobject(struct block_device *bdev, struct kobject *kobj)
+{
+ struct bd_holder *bo;
+
+ if (!kobj)
+ return;
+
+ down(&bdev->bd_sem);
+ bd_release(bdev);
+ if ((bo = del_bd_holder(bdev, kobj)))
+ free_bd_holder(bo);
+ up(&bdev->bd_sem);
+}
+
+EXPORT_SYMBOL(bd_release_from_kobject);
+
+/*
* Tries to open block device by device number. Use it ONLY if you
* really do not have anything better - i.e. when you are behind a
* truly sucky interface and all you are given is a device number. _Never_
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