Commit 62c053fb authored Jan 26, 2021 by Qu Wenruo Committed by David Sterba Feb 08, 2021

btrfs: set UNMAPPED bit early in btrfs_clone_extent_buffer() for subpage support



For the incoming subpage support, UNMAPPED extent buffer will have
different behavior in btrfs_release_extent_buffer().

This means we need to set UNMAPPED bit early before calling
btrfs_release_extent_buffer().

Currently there is only one caller which relies on
btrfs_release_extent_buffer() in its error path while set UNMAPPED bit
late:
- btrfs_clone_extent_buffer()

Make it subpage compatible by setting the UNMAPPED bit early, since
we're here, also move the UPTODATE bit early.

There is another caller, __alloc_dummy_extent_buffer(), setting
UNMAPPED bit late, but that function clean up the allocated page
manually, thus no need for any modification.

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 6869b0a8

fs/btrfs/extent_io.c

+7 −2

Original line number	Diff line number	Diff line
		@@ -5064,6 +5064,13 @@ struct extent_buffer btrfs_clone_extent_buffer(const struct extent_buffer src)
		if (new == NULL)
		return NULL;

		/*
		* Set UNMAPPED before calling btrfs_release_extent_buffer(), as
		* btrfs_release_extent_buffer() have different behavior for
		* UNMAPPED subpage extent buffer.
		*/
		set_bit(EXTENT_BUFFER_UNMAPPED, &new->bflags);

		for (i = 0; i < num_pages; i++) {
		p = alloc_page(GFP_NOFS);
		if (!p) {
		@@ -5076,9 +5083,7 @@ struct extent_buffer btrfs_clone_extent_buffer(const struct extent_buffer src)
		new->pages[i] = p;
		copy_page(page_address(p), page_address(src->pages[i]));
		}

		set_bit(EXTENT_BUFFER_UPTODATE, &new->bflags);
		set_bit(EXTENT_BUFFER_UNMAPPED, &new->bflags);

		return new;
		}