btrfs: make btrfs_fs_info::buffer_radix to take sector size devided v…

…alues

For subpage size sector size support, one page can contain mutliple tree
blocks, thus we can no longer use (eb->start >> PAGE_SHIFT) any more, or
we can easily get extent buffer doesn't belongs to us.

This patch will use (extent_buffer::start / sectorsize) as index for radix
tree so that we can get correct extent buffer for subpage size support.

Signed-off-by: Qu Wenruo <wqu@suse.com>
Reviewed-by: Nikolay Borisov <nborisov@suse.com>

fs/btrfs/extent_io.c

@@ -5142,7 +5142,7 @@ struct extent_buffer *find_extent_buffer(struct btrfs_fs_info *fs_info,
 
 	rcu_read_lock();
 	eb = radix_tree_lookup(&fs_info->buffer_radix,
-			       start >> PAGE_SHIFT);
+			       start / fs_info->sectorsize);
 	if (eb && atomic_inc_not_zero(&eb->refs)) {
 		rcu_read_unlock();
 		/*
@@ -5194,7 +5194,7 @@ struct extent_buffer *alloc_test_extent_buffer(struct btrfs_fs_info *fs_info,
 	}
 	spin_lock(&fs_info->buffer_lock);
 	ret = radix_tree_insert(&fs_info->buffer_radix,
-				start >> PAGE_SHIFT, eb);
+				start / fs_info->sectorsize, eb);
 	spin_unlock(&fs_info->buffer_lock);
 	radix_tree_preload_end();
 	if (ret == -EEXIST) {
@@ -5302,7 +5302,7 @@ struct extent_buffer *alloc_extent_buffer(struct btrfs_fs_info *fs_info,
 
 	spin_lock(&fs_info->buffer_lock);
 	ret = radix_tree_insert(&fs_info->buffer_radix,
-				start >> PAGE_SHIFT, eb);
+				start / fs_info->sectorsize, eb);
 	spin_unlock(&fs_info->buffer_lock);
 	radix_tree_preload_end();
 	if (ret == -EEXIST) {
@@ -5358,7 +5358,7 @@ static int release_extent_buffer(struct extent_buffer *eb)
 
 			spin_lock(&fs_info->buffer_lock);
 			radix_tree_delete(&fs_info->buffer_radix,
-					  eb->start >> PAGE_SHIFT);
+					  eb->start / fs_info->sectorsize);
 			spin_unlock(&fs_info->buffer_lock);
 		} else {
 			spin_unlock(&eb->refs_lock);