ext2fs: Bring back the htree dir_index implementation.

The htree dir_index is perhaps one of the most characteristic
features of the linux ext3 implementation. It was removed
in r281670, due to repeated bug reports.

Damjan Jovanic detected and fixed three bugs and did some
stress testing by building Apache OpenOffice on top of it
so it is now in good shape to bring back.

Differential Revision:	https://reviews.freebsd.org/D5007

Submitted by:	Damjan Jovanovic
Reviewed by:	pfg
Tested by:	pho
Relnotes:	Yes
MFC after:	2 months (only 10.x)

1 files changed, 8 insertions, 0 deletions

diff --git a/sys/fs/ext2fs/ext2fs.h b/sys/fs/ext2fs/ext2fs.h
index 756803f395c1..b8c4701181ea 100644
--- a/sys/fs/ext2fs/ext2fs.h
+++ b/sys/fs/ext2fs/ext2fs.h
@@ -147,6 +147,7 @@ struct m_ext2fs {
 	int32_t  e2fs_contigsumsize;    /* size of cluster summary array */
 	int32_t *e2fs_maxcluster;       /* max cluster in each cyl group */
 	struct   csum *e2fs_clustersum; /* cluster summary in each cyl group */
+	int32_t  e2fs_uhash;	  /* 3 if hash should be signed, 0 if not */
 };
 
 /* cluster summary information */
@@ -213,6 +214,7 @@ struct csum {
  * - EXT2F_INCOMPAT_FLEX_BG
  * - EXT2F_INCOMPAT_META_BG
  */
+#define	EXT2F_COMPAT_SUPP		EXT2F_COMPAT_DIRHASHINDEX
 #define	EXT2F_ROCOMPAT_SUPP		(EXT2F_ROCOMPAT_SPARSESUPER | \
 					 EXT2F_ROCOMPAT_LARGEFILE | \
 					 EXT2F_ROCOMPAT_EXTRA_ISIZE)
@@ -243,6 +245,12 @@ struct csum {
 #define	E2FS_ISCLEAN			0x0001	/* Unmounted cleanly */
 #define	E2FS_ERRORS			0x0002	/* Errors detected */
 
+/*
+ * Filesystem miscellaneous flags
+ */
+#define	E2FS_SIGNED_HASH	0x0001
+#define	E2FS_UNSIGNED_HASH	0x0002
+
 /* ext2 file system block group descriptor */
 
 struct ext2_gd {