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[PATCH] dm: add DMF_FREEING
There is a chicken and egg problem between the block layer and dm in which the gendisk associated with a mapping keeps a reference-less pointer to the mapped_device. This patch uses a new flag DMF_FREEING to indicate when the mapped_device is no longer valid. This is checked to prevent any attempt to open the device from succeeding while the device is being destroyed. [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>
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@ -63,6 +63,7 @@ union map_info *dm_get_mapinfo(struct bio *bio)
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#define DMF_BLOCK_IO 0
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#define DMF_BLOCK_IO 0
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#define DMF_SUSPENDED 1
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#define DMF_SUSPENDED 1
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#define DMF_FROZEN 2
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#define DMF_FROZEN 2
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#define DMF_FREEING 3
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struct mapped_device {
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struct mapped_device {
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struct rw_semaphore io_lock;
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struct rw_semaphore io_lock;
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@ -221,9 +222,23 @@ static int dm_blk_open(struct inode *inode, struct file *file)
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{
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{
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struct mapped_device *md;
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struct mapped_device *md;
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spin_lock(&_minor_lock);
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md = inode->i_bdev->bd_disk->private_data;
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md = inode->i_bdev->bd_disk->private_data;
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if (!md)
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goto out;
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if (test_bit(DMF_FREEING, &md->flags)) {
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md = NULL;
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goto out;
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}
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dm_get(md);
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dm_get(md);
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return 0;
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out:
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spin_unlock(&_minor_lock);
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return md ? 0 : -ENXIO;
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}
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}
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static int dm_blk_close(struct inode *inode, struct file *file)
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static int dm_blk_close(struct inode *inode, struct file *file)
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@ -919,6 +934,11 @@ static void free_dev(struct mapped_device *md)
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mempool_destroy(md->io_pool);
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mempool_destroy(md->io_pool);
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del_gendisk(md->disk);
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del_gendisk(md->disk);
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free_minor(minor);
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free_minor(minor);
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spin_lock(&_minor_lock);
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md->disk->private_data = NULL;
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spin_unlock(&_minor_lock);
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put_disk(md->disk);
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put_disk(md->disk);
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blk_cleanup_queue(md->queue);
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blk_cleanup_queue(md->queue);
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kfree(md);
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kfree(md);
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@ -1023,9 +1043,14 @@ static struct mapped_device *dm_find_md(dev_t dev)
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spin_lock(&_minor_lock);
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spin_lock(&_minor_lock);
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md = idr_find(&_minor_idr, minor);
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md = idr_find(&_minor_idr, minor);
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if (md && (md == MINOR_ALLOCED || (dm_disk(md)->first_minor != minor)))
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if (md && (md == MINOR_ALLOCED ||
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(dm_disk(md)->first_minor != minor) ||
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test_bit(DMF_FREEING, &md->flags))) {
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md = NULL;
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md = NULL;
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goto out;
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}
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out:
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spin_unlock(&_minor_lock);
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spin_unlock(&_minor_lock);
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return md;
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return md;
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@ -1060,9 +1085,12 @@ void dm_put(struct mapped_device *md)
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{
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{
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struct dm_table *map;
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struct dm_table *map;
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BUG_ON(test_bit(DMF_FREEING, &md->flags));
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if (atomic_dec_and_lock(&md->holders, &_minor_lock)) {
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if (atomic_dec_and_lock(&md->holders, &_minor_lock)) {
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map = dm_get_table(md);
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map = dm_get_table(md);
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idr_replace(&_minor_idr, MINOR_ALLOCED, dm_disk(md)->first_minor);
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idr_replace(&_minor_idr, MINOR_ALLOCED, dm_disk(md)->first_minor);
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set_bit(DMF_FREEING, &md->flags);
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spin_unlock(&_minor_lock);
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spin_unlock(&_minor_lock);
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if (!dm_suspended(md)) {
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if (!dm_suspended(md)) {
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dm_table_presuspend_targets(map);
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dm_table_presuspend_targets(map);
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