diff options
| author | Jeff Mahoney | 2006-06-26 00:27:21 -0700 |
|---|---|---|
| committer | Linus Torvalds | 2006-06-26 09:58:34 -0700 |
| commit | ba61fdd17d73ddb5c892a9f12383c6c560a20d56 (patch) | |
| tree | 7623bd742e2c142a8c5a1d8e5b940095b8673f3f | |
| parent | 5806f07cd2c32920d5105e0f9ff3117338f34eec (diff) | |
[PATCH] dm: fix idr minor allocation
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>
| -rw-r--r-- | drivers/md/dm.c | 19 |
1 files changed, 16 insertions, 3 deletions
diff --git a/drivers/md/dm.c b/drivers/md/dm.c index 4d710b7a133b..87d8ca1121e2 100644 --- a/drivers/md/dm.c +++ b/drivers/md/dm.c @@ -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); |