xfs: support in-memory btrees

Adapt the generic btree cursor code to be able to create a btree whose
buffers come from a (presumably in-memory) buftarg with a header block
that's specific to in-memory btrees.  We'll connect this to other parts
of online scrub in the next patches.

Note that in-memory btrees always have a block size matching the system
memory page size for efficiency reasons.

Signed-off-by: Darrick J. Wong <djwong@kernel.org>

1 files changed, 46 insertions, 0 deletions

diff --git a/fs/xfs/scrub/xfile.h b/fs/xfs/scrub/xfile.h
index c057bf786468..d9a09d71553b 100644
--- a/fs/xfs/scrub/xfile.h
+++ b/fs/xfs/scrub/xfile.h
@@ -62,6 +62,47 @@ int xfile_obj_put_page(struct xfile *xf, loff_t offset, unsigned int len,
 		struct page *page, void *fsdata);
 
 int xfile_dump(struct xfile *xf);
+
+static inline loff_t xfile_size(struct xfile *xf)
+{
+	return i_size_read(file_inode(xf->file));
+}
+
+/* file block (aka system page size) to basic block conversions. */
+typedef unsigned long long	xfileoff_t;
+#define XFB_BLOCKSIZE		(PAGE_SIZE)
+#define XFB_BSHIFT		(PAGE_SHIFT)
+#define XFB_SHIFT		(XFB_BSHIFT - BBSHIFT)
+
+static inline loff_t xfo_to_b(xfileoff_t xfoff)
+{
+	return xfoff << XFB_BSHIFT;
+}
+
+static inline xfileoff_t b_to_xfo(loff_t pos)
+{
+	return (pos + (XFB_BLOCKSIZE - 1)) >> XFB_BSHIFT;
+}
+
+static inline xfileoff_t b_to_xfot(loff_t pos)
+{
+	return pos >> XFB_BSHIFT;
+}
+
+static inline xfs_daddr_t xfo_to_daddr(xfileoff_t xfoff)
+{
+	return xfoff << XFB_SHIFT;
+}
+
+static inline xfileoff_t xfs_daddr_to_xfo(xfs_daddr_t bb)
+{
+	return (bb + (xfo_to_daddr(1) - 1)) >> XFB_SHIFT;
+}
+
+static inline xfileoff_t xfs_daddr_to_xfot(xfs_daddr_t bb)
+{
+	return bb >> XFB_SHIFT;
+}
 #else
 static inline int
 xfile_obj_load(struct xfile *xf, void *buf, size_t count, loff_t offset)
@@ -74,6 +115,11 @@ xfile_obj_store(struct xfile *xf, const void *buf, size_t count, loff_t offset)
 {
 	return -EIO;
 }
+
+static inline loff_t xfile_size(struct xfile *xf)
+{
+	return 0;
+}
 #endif /* CONFIG_XFS_IN_MEMORY_FILE */
 
 #endif /* __XFS_SCRUB_XFILE_H__ */