Commit 81982210 authored by Qu Wenruo's avatar Qu Wenruo Committed by David Sterba
Browse files

btrfs: make grab_extent_buffer_from_page() handle subpage case 



For subpage case, grab_extent_buffer() can't really get an extent buffer
just from btrfs_subpage.

We have radix tree lock protecting us from inserting the same eb into
the tree.  Thus we don't really need to do the extra hassle, just let
alloc_extent_buffer() handle the existing eb in radix tree.

Now if two ebs are being allocated as the same time, one will fail with
-EEIXST when inserting into the radix tree.

So for grab_extent_buffer(), just always return NULL for subpage case.

Reviewed-by: default avatarJosef Bacik <josef@toxicpanda.com>
Signed-off-by: default avatarQu Wenruo <wqu@suse.com>
Reviewed-by: default avatarDavid Sterba <dsterba@suse.com>
Signed-off-by: default avatarDavid Sterba <dsterba@suse.com>
parent 760f991f

fs/btrfs/extent_io.c

+11 −2
Original line number Diff line number Diff line
@@ -5284,10 +5284,19 @@ struct extent_buffer *alloc_test_extent_buffer(struct btrfs_fs_info *fs_info, 
}

#endif



static struct extent_buffer *grab_extent_buffer(struct page *page)

static struct extent_buffer *grab_extent_buffer(

		struct btrfs_fs_info *fs_info, struct page *page)

{

	struct extent_buffer *exists;



	/*

	 * For subpage case, we completely rely on radix tree to ensure we

	 * don't try to insert two ebs for the same bytenr.  So here we always

	 * return NULL and just continue.

	 */

	if (fs_info->sectorsize < PAGE_SIZE)

		return NULL;



	/* Page not yet attached to an extent buffer */

	if (!PagePrivate(page))

		return NULL;
@@ -5373,7 +5382,7 @@ struct extent_buffer *alloc_extent_buffer(struct btrfs_fs_info *fs_info, 
		}



		spin_lock(&mapping->private_lock);

		exists = grab_extent_buffer(p);

		exists = grab_extent_buffer(fs_info, p);

		if (exists) {

			spin_unlock(&mapping->private_lock);

			unlock_page(p);