btrfs: make attach_extent_buffer_page() handle subpage case
For subpage case, we need to allocate additional memory for each metadata page. So we need to: - Allow attach_extent_buffer_page() to return int to indicate allocation failure - Allow manually pre-allocate subpage memory for alloc_extent_buffer() As we don't want to use GFP_ATOMIC under spinlock, we introduce btrfs_alloc_subpage() and btrfs_free_subpage() functions for this purpose. (The simple wrap for btrfs_free_subpage() is for later convert to kmem_cache. Already internally tested without problem) - Preallocate btrfs_subpage structure for alloc_extent_buffer() We don't want to call memory allocation with spinlock held, so do preallocation before we acquire mapping->private_lock. - Handle subpage and regular case differently in attach_extent_buffer_page() For regular case, no change, just do the usual thing. For subpage case, allocate new memory or use the preallocated memory. For future subpage metadata, we will make use of radix tree to grab extent buffer. Reviewed-by:Josef Bacik <josef@toxicpanda.com> Signed-off-by:
Qu Wenruo <wqu@suse.com> Reviewed-by:
David Sterba <dsterba@suse.com> Signed-off-by:
David Sterba <dsterba@suse.com>
parent
cac06d84
Please register or sign in to comment