@@ -11,7 +11,8 @@ btrfs-y += super.o ctree.o extent-tree.o print-tree.o root-tree.o dir-item.o \
compression.o delayed-ref.o relocation.o delayed-inode.o scrub.o \
reada.o backref.o ulist.o qgroup.o send.o dev-replace.o raid56.o \
uuid-tree.o props.o free-space-tree.o tree-checker.o space-info.o \
- block-rsv.o delalloc-space.o block-group.o discard.o reflink.o
+ block-rsv.o delalloc-space.o block-group.o discard.o reflink.o \
+ subpage.o
btrfs-$(CONFIG_BTRFS_FS_POSIX_ACL) += acl.o
btrfs-$(CONFIG_BTRFS_FS_CHECK_INTEGRITY) += check-integrity.o
new file mode 100644
@@ -0,0 +1,39 @@
+// SPDX-License-Identifier: GPL-2.0
+
+#include "subpage.h"
+
+int btrfs_attach_subpage(struct btrfs_fs_info *fs_info, struct page *page)
+{
+ struct btrfs_subpage *subpage;
+
+ /*
+ * We have cases like a dummy extent buffer page, which is not
+ * mappped and doesn't need to be locked.
+ */
+ if (page->mapping)
+ ASSERT(PageLocked(page));
+ /* Either not subpage, or the page already has private attached */
+ if (fs_info->sectorsize == PAGE_SIZE || PagePrivate(page))
+ return 0;
+
+ subpage = kzalloc(sizeof(*subpage), GFP_NOFS);
+ if (!subpage)
+ return -ENOMEM;
+
+ spin_lock_init(&subpage->lock);
+ attach_page_private(page, subpage);
+ return 0;
+}
+
+void btrfs_detach_subpage(struct btrfs_fs_info *fs_info, struct page *page)
+{
+ struct btrfs_subpage *subpage;
+
+ /* Either not subpage, or already detached */
+ if (fs_info->sectorsize == PAGE_SIZE || !PagePrivate(page))
+ return;
+
+ subpage = (struct btrfs_subpage *)detach_page_private(page);
+ ASSERT(subpage);
+ kfree(subpage);
+}
new file mode 100644
@@ -0,0 +1,31 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+
+#ifndef BTRFS_SUBPAGE_H
+#define BTRFS_SUBPAGE_H
+
+#include <linux/spinlock.h>
+#include "ctree.h"
+
+/*
+ * Since the maximum page size btrfs is going to support is 64K while the
+ * minimum sectorsize is 4K, this means a u16 bitmap is enough.
+ *
+ * The regular bitmap requires 32 bits as minimal bitmap size, so we can't use
+ * existing bitmap_* helpers here.
+ */
+#define BTRFS_SUBPAGE_BITMAP_SIZE 16
+
+/*
+ * Structure to trace status of each sector inside a page.
+ *
+ * Will be attached to page::private for both data and metadata inodes.
+ */
+struct btrfs_subpage {
+ /* Common members for both data and metadata pages */
+ spinlock_t lock;
+};
+
+int btrfs_attach_subpage(struct btrfs_fs_info *fs_info, struct page *page);
+void btrfs_detach_subpage(struct btrfs_fs_info *fs_info, struct page *page);
+
+#endif /* BTRFS_SUBPAGE_H */