1 files changed, 127 insertions, 57 deletions

diff --git a/drivers/md/dm.c b/drivers/md/dm.c
index 4d710b7a133b..3ed2e53b9eb6 100644
--- a/drivers/md/dm.c
+++ b/drivers/md/dm.c
@@ -1,6 +1,6 @@
 /*
  * Copyright (C) 2001, 2002 Sistina Software (UK) Limited.
- * Copyright (C) 2004 Red Hat, Inc. All rights reserved.
+ * Copyright (C) 2004-2006 Red Hat, Inc. All rights reserved.
  *
  * This file is released under the GPL.
  */
@@ -21,11 +21,14 @@
 #include <linux/hdreg.h>
 #include <linux/blktrace_api.h>
 
+#define DM_MSG_PREFIX "core"
+
 static const char *_name = DM_NAME;
 
 static unsigned int major = 0;
 static unsigned int _major = 0;
 
+static DEFINE_SPINLOCK(_minor_lock);
 /*
  * One of these is allocated per bio.
  */
@@ -49,23 +52,28 @@ struct target_io {
 
 union map_info *dm_get_mapinfo(struct bio *bio)
 {
-        if (bio && bio->bi_private)
-                return &((struct target_io *)bio->bi_private)->info;
-        return NULL;
+        if (bio && bio->bi_private)
+                return &((struct target_io *)bio->bi_private)->info;
+        return NULL;
 }
 
+#define MINOR_ALLOCED ((void *)-1)
+
 /*
  * Bits for the md->flags field.
  */
 #define DMF_BLOCK_IO 0
 #define DMF_SUSPENDED 1
 #define DMF_FROZEN 2
+#define DMF_FREEING 3
+#define DMF_DELETING 4
 
 struct mapped_device {
         struct rw_semaphore io_lock;
         struct semaphore suspend_lock;
         rwlock_t map_lock;
         atomic_t holders;
+        atomic_t open_count;
 
         unsigned long flags;
 
@@ -218,9 +226,25 @@ static int dm_blk_open(struct inode *inode, struct file *file)
 {
         struct mapped_device *md;
 
+        spin_lock(&_minor_lock);
+
         md = inode->i_bdev->bd_disk->private_data;
+        if (!md)
+                goto out;
+
+        if (test_bit(DMF_FREEING, &md->flags) ||
+            test_bit(DMF_DELETING, &md->flags)) {
+                md = NULL;
+                goto out;
+        }
+
         dm_get(md);
-        return 0;
+        atomic_inc(&md->open_count);
+
+out:
+        spin_unlock(&_minor_lock);
+
+        return md ? 0 : -ENXIO;
 }
 
 static int dm_blk_close(struct inode *inode, struct file *file)
@@ -228,10 +252,35 @@ static int dm_blk_close(struct inode *inode, struct file *file)
         struct mapped_device *md;
 
         md = inode->i_bdev->bd_disk->private_data;
+        atomic_dec(&md->open_count);
         dm_put(md);
         return 0;
 }
 
+int dm_open_count(struct mapped_device *md)
+{
+        return atomic_read(&md->open_count);
+}
+
+/*
+ * Guarantees nothing is using the device before it's deleted.
+ */
+int dm_lock_for_deletion(struct mapped_device *md)
+{
+        int r = 0;
+
+        spin_lock(&_minor_lock);
+
+        if (dm_open_count(md))
+                r = -EBUSY;
+        else
+                set_bit(DMF_DELETING, &md->flags);
+
+        spin_unlock(&_minor_lock);
+
+        return r;
+}
+
 static int dm_blk_getgeo(struct block_device *bdev, struct hd_geometry *geo)
 {
         struct mapped_device *md = bdev->bd_disk->private_data;
@@ -456,8 +505,8 @@ static void __map_bio(struct dm_target *ti, struct bio *clone,
         if (r > 0) {
                 /* the bio has been remapped so dispatch it */
 
-                blk_add_trace_remap(bdev_get_queue(clone->bi_bdev), clone, 
-                                    tio->io->bio->bi_bdev->bd_dev, sector, 
+                blk_add_trace_remap(bdev_get_queue(clone->bi_bdev), clone,
+                                    tio->io->bio->bi_bdev->bd_dev, sector,
                                     clone->bi_sector);
 
                 generic_make_request(clone);
@@ -744,43 +793,39 @@ static int dm_any_congested(void *congested_data, int bdi_bits)
 /*-----------------------------------------------------------------
  * An IDR is used to keep track of allocated minor numbers.
  *---------------------------------------------------------------*/
-static DEFINE_MUTEX(_minor_lock);
 static DEFINE_IDR(_minor_idr);
 
-static void free_minor(unsigned int minor)
+static void free_minor(int minor)
 {
-        mutex_lock(&_minor_lock);
+        spin_lock(&_minor_lock);
         idr_remove(&_minor_idr, minor);
-        mutex_unlock(&_minor_lock);
+        spin_unlock(&_minor_lock);
 }
 
 /*
  * See if the device with a specific minor # is free.
  */
-static int specific_minor(struct mapped_device *md, unsigned int minor)
+static int specific_minor(struct mapped_device *md, int minor)
 {
         int r, m;
 
         if (minor >= (1 << MINORBITS))
                 return -EINVAL;
 
-        mutex_lock(&_minor_lock);
+        r = idr_pre_get(&_minor_idr, GFP_KERNEL);
+        if (!r)
+                return -ENOMEM;
+
+        spin_lock(&_minor_lock);
 
         if (idr_find(&_minor_idr, minor)) {
                 r = -EBUSY;
                 goto out;
         }
 
-        r = idr_pre_get(&_minor_idr, GFP_KERNEL);
-        if (!r) {
-                r = -ENOMEM;
-                goto out;
-        }
-
-        r = idr_get_new_above(&_minor_idr, md, minor, &m);
-        if (r) {
+        r = idr_get_new_above(&_minor_idr, MINOR_ALLOCED, minor, &m);
+        if (r)
                 goto out;
-        }
 
         if (m != minor) {
                 idr_remove(&_minor_idr, m);
@@ -789,24 +834,21 @@ static int specific_minor(struct mapped_device *md, unsigned int minor)
         }
 
 out:
-        mutex_unlock(&_minor_lock);
+        spin_unlock(&_minor_lock);
         return r;
 }
 
-static int next_free_minor(struct mapped_device *md, unsigned int *minor)
+static int next_free_minor(struct mapped_device *md, int *minor)
 {
-        int r;
-        unsigned int m;
-
-        mutex_lock(&_minor_lock);
+        int r, m;
 
         r = idr_pre_get(&_minor_idr, GFP_KERNEL);
-        if (!r) {
-                r = -ENOMEM;
-                goto out;
-        }
+        if (!r)
+                return -ENOMEM;
+
+        spin_lock(&_minor_lock);
 
-        r = idr_get_new(&_minor_idr, md, &m);
+        r = idr_get_new(&_minor_idr, MINOR_ALLOCED, &m);
         if (r) {
                 goto out;
         }
@@ -820,7 +862,7 @@ static int next_free_minor(struct mapped_device *md, unsigned int *minor)
         *minor = m;
 
 out:
-        mutex_unlock(&_minor_lock);
+        spin_unlock(&_minor_lock);
         return r;
 }
 
@@ -829,18 +871,25 @@ static struct block_device_operations dm_blk_dops;
 /*
  * Allocate and initialise a blank device with a given minor.
  */
-static struct mapped_device *alloc_dev(unsigned int minor, int persistent)
+static struct mapped_device *alloc_dev(int minor)
 {
         int r;
         struct mapped_device *md = kmalloc(sizeof(*md), GFP_KERNEL);
+        void *old_md;
 
         if (!md) {
                 DMWARN("unable to allocate device, out of memory.");
                 return NULL;
         }
 
+        if (!try_module_get(THIS_MODULE))
+                goto bad0;
+
         /* get a minor number for the dev */
-        r = persistent ? specific_minor(md, minor) : next_free_minor(md, &minor);
+        if (minor == DM_ANY_MINOR)
+                r = next_free_minor(md, &minor);
+        else
+                r = specific_minor(md, minor);
         if (r < 0)
                 goto bad1;
 
@@ -849,6 +898,7 @@ static struct mapped_device *alloc_dev(unsigned int minor, int persistent)
         init_MUTEX(&md->suspend_lock);
         rwlock_init(&md->map_lock);
         atomic_set(&md->holders, 1);
+        atomic_set(&md->open_count, 0);
         atomic_set(&md->event_nr, 0);
 
         md->queue = blk_alloc_queue(GFP_KERNEL);
@@ -875,6 +925,10 @@ static struct mapped_device *alloc_dev(unsigned int minor, int persistent)
         if (!md->disk)
                 goto bad4;
 
+        atomic_set(&md->pending, 0);
+        init_waitqueue_head(&md->wait);
+        init_waitqueue_head(&md->eventq);
+
         md->disk->major = _major;
         md->disk->first_minor = minor;
         md->disk->fops = &dm_blk_dops;
@@ -884,9 +938,12 @@ static struct mapped_device *alloc_dev(unsigned int minor, int persistent)
         add_disk(md->disk);
         format_dev_t(md->name, MKDEV(_major, minor));
 
-        atomic_set(&md->pending, 0);
-        init_waitqueue_head(&md->wait);
-        init_waitqueue_head(&md->eventq);
+        /* Populate the mapping, nobody knows we exist yet */
+        spin_lock(&_minor_lock);
+        old_md = idr_replace(&_minor_idr, md, minor);
+        spin_unlock(&_minor_lock);
+
+        BUG_ON(old_md != MINOR_ALLOCED);
 
         return md;
 
@@ -898,13 +955,15 @@ static struct mapped_device *alloc_dev(unsigned int minor, int persistent)
         blk_cleanup_queue(md->queue);
         free_minor(minor);
  bad1:
+        module_put(THIS_MODULE);
+ bad0:
         kfree(md);
         return NULL;
 }
 
 static void free_dev(struct mapped_device *md)
 {
-        unsigned int minor = md->disk->first_minor;
+        int minor = md->disk->first_minor;
 
         if (md->suspended_bdev) {
                 thaw_bdev(md->suspended_bdev, NULL);
@@ -914,8 +973,14 @@ static void free_dev(struct mapped_device *md)
         mempool_destroy(md->io_pool);
         del_gendisk(md->disk);
         free_minor(minor);
+
+        spin_lock(&_minor_lock);
+        md->disk->private_data = NULL;
+        spin_unlock(&_minor_lock);
+
         put_disk(md->disk);
         blk_cleanup_queue(md->queue);
+        module_put(THIS_MODULE);
         kfree(md);
 }
 
@@ -984,12 +1049,11 @@ static void __unbind(struct mapped_device *md)
 /*
  * Constructor for a new device.
  */
-static int create_aux(unsigned int minor, int persistent,
-                      struct mapped_device **result)
+int dm_create(int minor, struct mapped_device **result)
 {
         struct mapped_device *md;
 
-        md = alloc_dev(minor, persistent);
+        md = alloc_dev(minor);
         if (!md)
                 return -ENXIO;
 
@@ -997,16 +1061,6 @@ static int create_aux(unsigned int minor, int persistent,
         return 0;
 }
 
-int dm_create(struct mapped_device **result)
-{
-        return create_aux(0, 0, result);
-}
-
-int dm_create_with_minor(unsigned int minor, struct mapped_device **result)
-{
-        return create_aux(minor, 1, result);
-}
-
 static struct mapped_device *dm_find_md(dev_t dev)
 {
         struct mapped_device *md;
@@ -1015,13 +1069,18 @@ static struct mapped_device *dm_find_md(dev_t dev)
         if (MAJOR(dev) != _major || minor >= (1 << MINORBITS))
                 return NULL;
 
-        mutex_lock(&_minor_lock);
+        spin_lock(&_minor_lock);
 
         md = idr_find(&_minor_idr, minor);
-        if (!md || (dm_disk(md)->first_minor != minor))
+        if (md && (md == MINOR_ALLOCED ||
+                   (dm_disk(md)->first_minor != minor) ||
+                   test_bit(DMF_FREEING, &md->flags))) {
                 md = NULL;
+                goto out;
+        }
 
-        mutex_unlock(&_minor_lock);
+out:
+        spin_unlock(&_minor_lock);
 
         return md;
 }
@@ -1051,12 +1110,23 @@ void dm_get(struct mapped_device *md)
         atomic_inc(&md->holders);
 }
 
+const char *dm_device_name(struct mapped_device *md)
+{
+        return md->name;
+}
+EXPORT_SYMBOL_GPL(dm_device_name);
+
 void dm_put(struct mapped_device *md)
 {
         struct dm_table *map;
 
-        if (atomic_dec_and_test(&md->holders)) {
+        BUG_ON(test_bit(DMF_FREEING, &md->flags));
+
+        if (atomic_dec_and_lock(&md->holders, &_minor_lock)) {
                 map = dm_get_table(md);
+                idr_replace(&_minor_idr, MINOR_ALLOCED, dm_disk(md)->first_minor);
+                set_bit(DMF_FREEING, &md->flags);
+                spin_unlock(&_minor_lock);
                 if (!dm_suspended(md)) {
                         dm_table_presuspend_targets(map);
                         dm_table_postsuspend_targets(map);