There is a indirect recursion which can reach the extent reservation:
btrfs_reserve_extent() <--|
|- do_chunk_alloc() |
|- btrfs_alloc_chunk() |
|- btrfs_insert_item() |
|- btrfs_reserve_extent() <--|
Currently, we're using root->ref_cows to determine whether we should do
chunk prealloc to avoid such loop.
But that's still a hidden trap. Instead of solving it using some hidden
tricks, this patch will make chunk/block group allocation exclusive.
Now if do_chunk_alloc() determines to alloc chunk, it will set a flag in
transaction handle so new call of do_chunk_alloc() will refuse to
allocate new chunk until current chunk allocation finishes.
The chunks get over-allocated by 2M so there's enough space in case the
recursive call asks for a different type of blockgroup.
Signed-off-by: Qu Wenruo <wqu@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
This commit pulls those portions of the kernel implementation of
delayed refs which are necessary to have them working in user-space.
I've done the following modifications:
1. Replaced all kmem_cache_alloc calls to kmalloc.
2. Removed all locking-related code, since we are single threaded in
userspace.
3. Removed code which deals with data refs - delayed refs in user space
are going to be used only for cowonly trees.
Signed-off-by: Nikolay Borisov <nborisov@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
Add a boolean to record whether the extent tree is being re-initialised
in the current transaction. This is going to be needed by the
delayed refs code.
Signed-off-by: Nikolay Borisov <nborisov@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
Add includes that let the header files compile or add explicit include
of kerncompat if the uXX types are used.
Signed-off-by: David Sterba <dsterba@suse.cz>
Qu Wenruo