This patch is part of dm/md sysfs dependency tree.
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 | 196 +++++++++++++++++++++++++++++++++++++++++++++++++++-
include/linux/fs.h | 3
2 files changed, 197 insertions(+), 2 deletions(-)
--- linux-2.6.16-rc5.orig/include/linux/fs.h 2006-02-27 00:09:35.000000000 -0500
+++ linux-2.6.16-rc5/include/linux/fs.h 2006-03-02 10:29:55.000000000 -0500
@@ -401,6 +401,7 @@ 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;
@@ -1380,6 +1381,8 @@ 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-rc5.orig/fs/block_dev.c 2006-02-27 00:09:35.000000000 -0500
+++ linux-2.6.16-rc5/fs/block_dev.c 2006-03-02 10:29:55.000000000 -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);
}
}
@@ -443,7 +444,179 @@ void bd_forget(struct inode *inode)
spin_unlock(&bdev_lock);
}
-int bd_claim(struct block_device *bdev, void *holder)
+/*
+ * 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)
+ 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 struct kobject * bdev_get_holder(struct block_device *bdev)
+{
+ if (!bdev)
+ return NULL;
+ else 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;
+ kobject_get(from);
+ kobject_get(to);
+ 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));
+ kobject_put(from);
+ kobject_put(to);
+}
+
+static inline int bd_claim_grab_dirs(struct block_device *bdev,
+ struct kobject *holder,
+ struct kobject **sdir, struct kobject **sdev,
+ struct kobject **hdir, struct kobject **hdev)
+{
+ *sdir = kobject_get(holder);
+ if (!*sdir)
+ return 0;
+
+ *hdev = kobject_get((*sdir)->parent);
+ if (!*hdev)
+ goto fail_put_sdir;
+
+ *sdev = bdev_get_kobj(bdev);
+ if (!*sdev)
+ goto fail_put_hdev;
+
+ *hdir = bdev_get_holder(bdev);
+ if (!*hdir)
+ goto fail_put_sdev;
+
+ return 1;
+
+fail_put_sdev:
+ kobject_put(*sdev);
+fail_put_hdev:
+ kobject_put(*hdev);
+fail_put_sdir:
+ kobject_put(*sdir);
+
+ return 0;
+}
+
+static inline void bd_claim_release_dirs(
+ struct kobject *sdir, struct kobject *sdev,
+ struct kobject *hdir, struct kobject *hdev)
+{
+ kobject_put(hdir);
+ kobject_put(sdev);
+ kobject_put(hdev);
+ kobject_put(sdir);
+}
+
+static void link_bd_holder(struct block_device *bdev, struct kobject *holder)
+{
+ struct kobject *sdir, *sdev, *hdir, *hdev;
+
+ if (bd_claim_grab_dirs(bdev, holder, &sdir, &sdev, &hdir, &hdev)) {
+ add_symlink(sdir, sdev);
+ add_symlink(hdir, hdev);
+ bd_claim_release_dirs(sdir, sdev, hdir, hdev);
+ }
+
+ return;
+}
+
+static void unlink_bd_holder(struct block_device *bdev, struct kobject *holder)
+{
+ struct kobject *sdir, *sdev, *hdir, *hdev;
+
+ if (bd_claim_grab_dirs(bdev, holder, &sdir, &sdev, &hdir, &hdev)) {
+ del_symlink(sdir, sdev);
+ del_symlink(hdir, hdev);
+ bd_claim_release_dirs(sdir, sdev, hdir, hdev);
+ }
+}
+
+/* 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 *kobj; /* holder kobject */
+};
+
+static int add_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->kobj == kobj) {
+ bo->count++;
+ return 0;
+ }
+ }
+
+ bo = kmalloc(sizeof(*bo), GFP_KERNEL);
+ if (!bo)
+ return -ENOMEM;
+
+ bo->count = 1;
+ bo->kobj = kobj;
+ list_add_tail(&bo->list, &bdev->bd_holder_list);
+ link_bd_holder(bdev, kobj);
+
+ return 0;
+}
+
+static int 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->kobj == kobj) {
+ bo->count--;
+ BUG_ON(bo->count < 0);
+ if (!bo->count) {
+ unlink_bd_holder(bdev, kobj);
+ list_del(&bo->list);
+ kfree(bo);
+ }
+ break;
+ }
+ }
+
+ return 0;
+}
+
+int bd_claim_by_kobject(struct block_device *bdev, void *holder, struct kobject *kobj)
{
int res;
spin_lock(&bdev_lock);
@@ -464,6 +637,9 @@ int bd_claim(struct block_device *bdev,
res = 0; /* is a partition of an un-held device */
/* now impose change */
+ if (res == 0 && kobj)
+ res = add_bd_holder(bdev, kobj);
+
if (res==0) {
/* note that for a whole device bd_holders
* will be incremented twice, and bd_holder will
@@ -478,11 +654,20 @@ int bd_claim(struct block_device *bdev,
return res;
}
+EXPORT_SYMBOL(bd_claim_by_kobject);
+
+int bd_claim(struct block_device *bdev, void *holder)
+{
+ return bd_claim_by_kobject(bdev, holder, NULL);
+}
+
EXPORT_SYMBOL(bd_claim);
-void bd_release(struct block_device *bdev)
+void bd_release_from_kobject(struct block_device *bdev, struct kobject *kobj)
{
spin_lock(&bdev_lock);
+ if (kobj)
+ del_bd_holder(bdev, kobj);
if (!--bdev->bd_contains->bd_holders)
bdev->bd_contains->bd_holder = NULL;
if (!--bdev->bd_holders)
@@ -490,6 +675,13 @@ void bd_release(struct block_device *bde
spin_unlock(&bdev_lock);
}
+EXPORT_SYMBOL(bd_release_from_kobject);
+
+void bd_release(struct block_device *bdev)
+{
+ bd_release_from_kobject(bdev, NULL);
+}
+
EXPORT_SYMBOL(bd_release);
/*
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