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Subject8/19
From
Give each device its own io mempool to avoid a potential
deadlock with stacked devices. [HM + EJT]
--- diff/drivers/md/dm.c 2002-12-16 09:40:44.000000000 +0000
+++ source/drivers/md/dm.c 2002-12-16 09:40:58.000000000 +0000
@@ -58,11 +58,15 @@
* The current mapping.
*/
struct dm_table *map;
+
+ /*
+ * io objects are allocated from here.
+ */
+ mempool_t *io_pool;
};

#define MIN_IOS 256
static kmem_cache_t *_io_cache;
-static mempool_t *_io_pool;

static __init int local_init(void)
{
@@ -74,18 +78,10 @@
if (!_io_cache)
return -ENOMEM;

- _io_pool = mempool_create(MIN_IOS, mempool_alloc_slab,
- mempool_free_slab, _io_cache);
- if (!_io_pool) {
- kmem_cache_destroy(_io_cache);
- return -ENOMEM;
- }
-
_major = major;
r = register_blkdev(_major, _name, &dm_blk_dops);
if (r < 0) {
DMERR("register_blkdev failed");
- mempool_destroy(_io_pool);
kmem_cache_destroy(_io_cache);
return r;
}
@@ -98,7 +94,6 @@

static void local_exit(void)
{
- mempool_destroy(_io_pool);
kmem_cache_destroy(_io_cache);

if (unregister_blkdev(_major, _name) < 0)
@@ -178,14 +173,14 @@
return 0;
}

-static inline struct dm_io *alloc_io(void)
+static inline struct dm_io *alloc_io(struct mapped_device *md)
{
- return mempool_alloc(_io_pool, GFP_NOIO);
+ return mempool_alloc(md->io_pool, GFP_NOIO);
}

-static inline void free_io(struct dm_io *io)
+static inline void free_io(struct mapped_device *md, struct dm_io *io)
{
- mempool_free(io, _io_pool);
+ mempool_free(io, md->io_pool);
}

static inline struct deferred_io *alloc_deferred(void)
@@ -254,7 +249,7 @@
wake_up(&io->md->wait);

bio_endio(io->bio, io->error ? 0 : io->bio->bi_size, io->error);
- free_io(io);
+ free_io(io->md, io);
}
}

@@ -419,7 +414,7 @@

ci.md = md;
ci.bio = bio;
- ci.io = alloc_io();
+ ci.io = alloc_io(md);
ci.io->error = 0;
atomic_set(&ci.io->io_count, 1);
ci.io->bio = bio;
@@ -558,8 +553,17 @@
md->queue.queuedata = md;
blk_queue_make_request(&md->queue, dm_request);

+ md->io_pool = mempool_create(MIN_IOS, mempool_alloc_slab,
+ mempool_free_slab, _io_cache);
+ if (!md->io_pool) {
+ free_minor(md->disk->first_minor);
+ kfree(md);
+ return NULL;
+ }
+
md->disk = alloc_disk(1);
if (!md->disk) {
+ mempool_destroy(md->io_pool);
free_minor(md->disk->first_minor);
kfree(md);
return NULL;
@@ -581,6 +585,7 @@
static void free_dev(struct mapped_device *md)
{
free_minor(md->disk->first_minor);
+ mempool_destroy(md->io_pool);
del_gendisk(md->disk);
put_disk(md->disk);
kfree(md);
-
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