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[PATCH] dm: fix idr minor allocation

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One part of the system can attempt to use a mapped device before another has
finished initialising it or while it is being freed.

This patch introduces a place holder value, MINOR_ALLOCED, to mark the minor
as allocated but in a state where it can't be used, such as mid-allocation or
mid-free.  At the end of the initialization, it replaces the place holder with
the pointer to the mapped_device, making it available to the rest of the dm
subsystem.

[akpm: too late for 2.6.17 - suitable for 2.6.17.x after it has settled]

Signed-off-by: Jeff Mahoney <jeffm@suse.com>
Signed-off-by: Alasdair G Kergon <agk@redhat.com>
Cc: <stable@kernel.org>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
This commit is contained in:
Jeff Mahoney 2006-06-26 00:27:21 -07:00 committed by Linus Torvalds
parent 5806f07cd2
commit ba61fdd17d
1 changed files with 16 additions and 3 deletions
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19
drivers/md/dm.c
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@ -54,6 +54,8 @@ union map_info *dm_get_mapinfo(struct bio *bio)
return NULL;
}
#define MINOR_ALLOCED ((void *)-1)
/*
* Bits for the md->flags field.
*/
@ -777,7 +779,7 @@ static int specific_minor(struct mapped_device *md, unsigned int minor)
goto out;
}
r = idr_get_new_above(&_minor_idr, md, minor, &m);
r = idr_get_new_above(&_minor_idr, MINOR_ALLOCED, minor, &m);
if (r) {
goto out;
}
@ -806,7 +808,7 @@ static int next_free_minor(struct mapped_device *md, unsigned int *minor)
goto out;
}
r = idr_get_new(&_minor_idr, md, &m);
r = idr_get_new(&_minor_idr, MINOR_ALLOCED, &m);
if (r) {
goto out;
}
@ -833,6 +835,7 @@ static struct mapped_device *alloc_dev(unsigned int minor, int persistent)
{
int r;
struct mapped_device *md = kmalloc(sizeof(*md), GFP_KERNEL);
void *old_md;
if (!md) {
DMWARN("unable to allocate device, out of memory.");
@ -888,6 +891,13 @@ static struct mapped_device *alloc_dev(unsigned int minor, int persistent)
init_waitqueue_head(&md->wait);
init_waitqueue_head(&md->eventq);
/* Populate the mapping, nobody knows we exist yet */
mutex_lock(&_minor_lock);
old_md = idr_replace(&_minor_idr, md, minor);
mutex_unlock(&_minor_lock);
BUG_ON(old_md != MINOR_ALLOCED);
return md;
bad4:
@ -1018,7 +1028,7 @@ static struct mapped_device *dm_find_md(dev_t dev)
mutex_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)))
md = NULL;
mutex_unlock(&_minor_lock);
@ -1057,6 +1067,9 @@ void dm_put(struct mapped_device *md)
if (atomic_dec_and_test(&md->holders)) {
map = dm_get_table(md);
mutex_lock(&_minor_lock);
idr_replace(&_minor_idr, MINOR_ALLOCED, dm_disk(md)->first_minor);
mutex_unlock(&_minor_lock);
if (!dm_suspended(md)) {
dm_table_presuspend_targets(map);
dm_table_postsuspend_targets(map);