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Date: Sat, 20 Oct 2012 20:32:22 +0200
From: Hannes Frederic Sowa <hannes@...essinduktion.org>
To: linux-kernel@...r.kernel.org
Cc: Hannes Frederic Sowa <hannes@...essinduktion.org>,
Nick Piggin <npiggin@...nel.dk>
Subject: [PATCH 3/4] brd: replace list with brd_devices by an idr indexed by minor ids
This patch replaces the list of brd_devices with an idr, thus enabling
easier block ram disk creation and deletion.
Cc: Nick Piggin <npiggin@...nel.dk>
Signed-off-by: Hannes Frederic Sowa <hannes@...essinduktion.org>
---
drivers/block/brd.c | 136 ++++++++++++++++++++++++++++++++++++++++------------
1 file changed, 106 insertions(+), 30 deletions(-)
diff --git a/drivers/block/brd.c b/drivers/block/brd.c
index ce1255c..1d0016b 100644
--- a/drivers/block/brd.c
+++ b/drivers/block/brd.c
@@ -19,6 +19,7 @@
#include <linux/radix-tree.h>
#include <linux/fs.h>
#include <linux/slab.h>
+#include <linux/idr.h>
#include <asm/uaccess.h>
@@ -34,11 +35,8 @@
* device).
*/
struct brd_device {
- int brd_number;
-
struct request_queue *brd_queue;
struct gendisk *brd_disk;
- struct list_head brd_list;
/*
* Backing store of pages and lock to protect it. This is the contents
@@ -50,6 +48,10 @@ struct brd_device {
static DEFINE_MUTEX(brd_mutex);
+static char dummy = -1;
+#define DUMMY ((struct brd_device *)&dummy)
+static DEFINE_IDR(brd_idr);
+
/*
* Look up and return a brd's page for a given sector.
*/
@@ -458,6 +460,8 @@ MODULE_LICENSE("GPL");
MODULE_ALIAS_BLOCKDEV_MAJOR(RAMDISK_MAJOR);
MODULE_ALIAS("rd");
+static struct brd_device *brd_new(int id);
+
#ifndef MODULE
/* Legacy boot options - nonmodular */
static int __init ramdisk_size(char *str)
@@ -472,7 +476,6 @@ __setup("ramdisk_size=", ramdisk_size);
* The device scheme is derived from loop.c. Keep them in synch where possible
* (should share code eventually).
*/
-static LIST_HEAD(brd_devices);
static DEFINE_MUTEX(brd_devices_mutex);
static struct brd_device *brd_alloc(int i)
@@ -483,7 +486,6 @@ static struct brd_device *brd_alloc(int i)
brd = kzalloc(sizeof(*brd), GFP_KERNEL);
if (!brd)
goto out;
- brd->brd_number = i;
spin_lock_init(&brd->brd_lock);
INIT_RADIX_TREE(&brd->brd_pages, GFP_ATOMIC);
@@ -533,27 +535,100 @@ static struct brd_device *brd_init_one(int i)
{
struct brd_device *brd;
- list_for_each_entry(brd, &brd_devices, brd_list) {
- if (brd->brd_number == i)
- goto out;
- }
+ brd = idr_find(&brd_idr, i);
+ if (brd)
+ return brd;
- brd = brd_alloc(i);
- if (brd) {
+ brd = brd_new(i);
+ if (!IS_ERR(brd))
add_disk(brd->brd_disk);
- list_add_tail(&brd->brd_list, &brd_devices);
- }
-out:
return brd;
}
static void brd_del_one(struct brd_device *brd)
{
- list_del(&brd->brd_list);
del_gendisk(brd->brd_disk);
brd_free(brd);
}
+static int brd_new_id(int min)
+{
+ int id, err;
+ err = idr_pre_get(&brd_idr, GFP_KERNEL);
+ if (!err)
+ return -ENOMEM;
+ err = idr_get_new_above(&brd_idr, DUMMY, min, &id);
+ if (err < 0)
+ return err;
+ return id;
+}
+
+static int brd_new_specific_id(int id)
+{
+ int n;
+ n = brd_new_id(id);
+ if (n < 0)
+ return n;
+ if (id != n) {
+ idr_remove(&brd_idr, n);
+ return -EBUSY;
+ }
+ return n;
+}
+
+static struct brd_device *brd_new(int id)
+{
+ int err;
+ struct brd_device *brd, *p;
+
+ err = brd_new_specific_id(id);
+ if (err < 0)
+ return ERR_PTR(err);
+ brd = brd_alloc(id);
+ if (!brd) {
+ p = ERR_PTR(-ENOMEM);
+ goto out;
+ }
+ p = idr_replace(&brd_idr, brd, id);
+ if (IS_ERR(p))
+ goto out2;
+ if (p != DUMMY) {
+ WARN_ON(1);
+ p = ERR_PTR(-EBUSY);
+ goto out2;
+ }
+ return brd;
+out2:
+ brd_free(brd);
+out:
+ idr_remove(&brd_idr, id);
+ return p;
+}
+
+static int brd_add_disk_idr(int id, void *p, void *data)
+{
+ struct brd_device *brd = (struct brd_device *)p;
+ WARN_ON(brd == DUMMY);
+ add_disk(brd->brd_disk);
+ return 0;
+}
+
+static int brd_free_idr(int id, void *p, void *data)
+{
+ struct brd_device *brd = (struct brd_device *)p;
+ WARN_ON(brd == DUMMY);
+ brd_free(brd);
+ return 0;
+}
+
+static int brd_del_one_idr(int id, void *p, void *data)
+{
+ struct brd_device *brd = (struct brd_device *)p;
+ WARN_ON(brd == DUMMY);
+ brd_del_one(brd);
+ return 0;
+}
+
static struct kobject *brd_probe(dev_t dev, int *part, void *data)
{
struct brd_device *brd;
@@ -561,7 +636,7 @@ static struct kobject *brd_probe(dev_t dev, int *part, void *data)
mutex_lock(&brd_devices_mutex);
brd = brd_init_one(MINOR(dev) >> part_shift);
- kobj = brd ? get_disk(brd->brd_disk) : ERR_PTR(-ENOMEM);
+ kobj = IS_ERR(brd) ? ERR_PTR(PTR_ERR(brd)) : get_disk(brd->brd_disk);
mutex_unlock(&brd_devices_mutex);
*part = 0;
@@ -570,9 +645,10 @@ static struct kobject *brd_probe(dev_t dev, int *part, void *data)
static int __init brd_init(void)
{
+ int err;
unsigned int i, nr;
unsigned long range;
- struct brd_device *brd, *next;
+ struct brd_device *brd;
/*
* brd module now has a feature to instantiate underlying device
@@ -619,16 +695,16 @@ static int __init brd_init(void)
return -EIO;
for (i = 0; i < nr; i++) {
- brd = brd_alloc(i);
- if (!brd)
+ brd = brd_new(i);
+ if (IS_ERR(brd)) {
+ err = PTR_RET(brd);
goto out_free;
- list_add_tail(&brd->brd_list, &brd_devices);
+ }
}
/* point of no return */
- list_for_each_entry(brd, &brd_devices, brd_list)
- add_disk(brd->brd_disk);
+ idr_for_each(&brd_idr, brd_add_disk_idr, NULL);
blk_register_region(MKDEV(RAMDISK_MAJOR, 0), range,
THIS_MODULE, brd_probe, NULL, NULL);
@@ -637,24 +713,24 @@ static int __init brd_init(void)
return 0;
out_free:
- list_for_each_entry_safe(brd, next, &brd_devices, brd_list) {
- list_del(&brd->brd_list);
- brd_free(brd);
- }
+ idr_for_each(&brd_idr, brd_free_idr, NULL);
+ idr_remove_all(&brd_idr);
+ idr_destroy(&brd_idr);
+
unregister_blkdev(RAMDISK_MAJOR, "ramdisk");
- return -ENOMEM;
+ return err;
}
static void __exit brd_exit(void)
{
unsigned long range;
- struct brd_device *brd, *next;
range = rd_nr ? rd_nr << part_shift : 1UL << MINORBITS;
- list_for_each_entry_safe(brd, next, &brd_devices, brd_list)
- brd_del_one(brd);
+ idr_for_each(&brd_idr, brd_del_one_idr, NULL);
+ idr_remove_all(&brd_idr);
+ idr_destroy(&brd_idr);
blk_unregister_region(MKDEV(RAMDISK_MAJOR, 0), range);
unregister_blkdev(RAMDISK_MAJOR, "ramdisk");
--
1.7.12.4
--
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