xfs: simplify validation of the unwritten extent bit

XFS only supports the unwritten extent bit in the data fork, and only if
the file system has a version 5 superblock or the unwritten extent
feature bit.

We currently have two routines that validate the invariant:
xfs_check_nostate_extents which return -EFSCORRUPTED when it's not met,
and xfs_validate_extent that triggers and assert in debug build.

Both of them iterate over all extents of an inode fork when called,
which isn't very efficient.

This patch instead adds a new helper that verifies the invariant one
extent at a time, and calls it from the places where we iterate over
all extents to converted them from or two the in-memory format.  The
callers then return -EFSCORRUPTED when reading invalid extents from
disk, or trigger an assert when writing them to disk.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Darrick J. Wong <darrick.wong@oracle.com>
Signed-off-by: Darrick J. Wong <darrick.wong@oracle.com>

1 files changed, 14 insertions, 7 deletions

diff --git a/fs/xfs/libxfs/xfs_bmap_btree.h b/fs/xfs/libxfs/xfs_bmap_btree.h
index 90347a99c6d2..9da5a8d4f184 100644
--- a/fs/xfs/libxfs/xfs_bmap_btree.h
+++ b/fs/xfs/libxfs/xfs_bmap_btree.h
@@ -25,13 +25,6 @@ struct xfs_inode;
 struct xfs_trans;
 
 /*
- * Extent state and extent format macros.
- */
-#define XFS_EXTFMT_INODE(x)	\
-	(xfs_sb_version_hasextflgbit(&((x)->i_mount->m_sb)) ? \
-		XFS_EXTFMT_HASSTATE : XFS_EXTFMT_NOSTATE)
-
-/*
  * Btree block header size depends on a superblock flag.
  */
 #define XFS_BMBT_BLOCK_LEN(mp) \
@@ -139,4 +132,18 @@ extern int xfs_bmbt_change_owner(struct xfs_trans *tp, struct xfs_inode *ip,
 extern struct xfs_btree_cur *xfs_bmbt_init_cursor(struct xfs_mount *,
 		struct xfs_trans *, struct xfs_inode *, int);
 
+/*
+ * Check that the extent does not contain an invalid unwritten extent flag.
+ */
+static inline bool xfs_bmbt_validate_extent(struct xfs_mount *mp, int whichfork,
+		struct xfs_bmbt_rec_host *ep)
+{
+	if (ep->l0 >> (64 - BMBT_EXNTFLAG_BITLEN) == 0)
+		return true;
+	if (whichfork == XFS_DATA_FORK &&
+	    xfs_sb_version_hasextflgbit(&mp->m_sb))
+		return true;
+	return false;
+}
+
 #endif	/* __XFS_BMAP_BTREE_H__ */