[PATCH 2/2] xfs_repair: new secondary superblock search method

["Bill O'Donnell" <billodo@redhat.com>]

Optimize secondary sb search, using similar method to find
fs geometry as that of xfs_mkfs. If this faster method fails
in finding a secondary sb, fall back to original brute force
slower search.

Signed-off-by: Bill O'Donnell <billodo@redhat.com>
---
 Makefile           |  2 +-
 include/libxcmd.h  |  4 +++-
 libxcmd/topology.c | 28 +++++++++++++++++++++++++++-
 repair/Makefile    |  4 ++--
 repair/phase1.c    | 25 +++++++++++++++++++++++--
 repair/protos.h    |  2 +-
 repair/sb.c        | 27 +++++++++++++++++++++------
 7 files changed, 78 insertions(+), 14 deletions(-)

diff --git a/Makefile b/Makefile
index fca0a42..1d60d9c 100644
--- a/Makefile
+++ b/Makefile
@@ -80,7 +80,7 @@ fsr: libhandle
 growfs: libxcmd
 io: libxcmd libhandle
 quota: libxcmd
-repair: libxlog
+repair: libxlog libxcmd
 copy: libxlog
 
 ifeq ($(HAVE_BUILDDEFS), yes)
diff --git a/include/libxcmd.h b/include/libxcmd.h
index df7046e..b140adb 100644
--- a/include/libxcmd.h
+++ b/include/libxcmd.h
@@ -50,6 +50,8 @@ extern int
 check_overwrite(
 	char		*device);
 
-
+extern int guess_default_geometry(__uint64_t *agsize,
+				  __uint64_t *agcount,
+				  libxfs_init_t x);
 
 #endif	/* __LIBXCMD_H__ */
diff --git a/libxcmd/topology.c b/libxcmd/topology.c
index 0eeea28..4a8ab8b 100644
--- a/libxcmd/topology.c
+++ b/libxcmd/topology.c
@@ -302,7 +302,6 @@ static void blkid_get_topology(
 
 #endif /* ENABLE_BLKID */
 
-
 void get_topology(
 	libxfs_init_t		*xi,
 	struct fs_topology	*ft,
@@ -346,3 +345,30 @@ void get_topology(
 				   &lsectorsize, &psectorsize, force_overwrite);
 	}
 }
+
+/*
+ * Use this macro before we have superblock and mount structure
+ */
+#define	DTOBT(d)	((xfs_rfsblock_t)((d) >> (blocklog - BBSHIFT)))
+
+int guess_default_geometry(__uint64_t *agsize, __uint64_t *agcount, libxfs_init_t x) {
+	struct fs_topology ft;
+	int blocklog;
+	__uint64_t      dblocks;
+	int             multidisk;
+        memset(&ft, 0, sizeof(ft));
+        get_topology(&x, &ft, 1);
+
+        /*
+	 * get geometry from get_topology result.
+	 * Use default block size (2^12)
+	 */
+        blocklog = 12;
+        multidisk = ft.dswidth | ft.dsunit;
+	printf("x.dsize = %lu\n",(long unsigned int)x.dsize);
+        dblocks = DTOBT(x.dsize);
+        calc_default_ag_geometry(blocklog, dblocks, multidisk,
+                                 agsize, agcount);
+
+	return(blocklog);
+}
diff --git a/repair/Makefile b/repair/Makefile
index 251722b..d24ab1f 100644
--- a/repair/Makefile
+++ b/repair/Makefile
@@ -20,8 +20,8 @@ CFILES = agheader.c attr_repair.c avl.c avl64.c bmap.c btree.c \
 	progress.c prefetch.c rt.c sb.c scan.c threads.c \
 	versions.c xfs_repair.c
 
-LLDLIBS = $(LIBXFS) $(LIBXLOG) $(LIBUUID) $(LIBRT) $(LIBPTHREAD)
-LTDEPENDENCIES = $(LIBXFS) $(LIBXLOG)
+LLDLIBS = $(LIBBLKID) $(LIBXFS) $(LIBXLOG) $(LIBUUID) $(LIBRT) $(LIBPTHREAD) $(LIBXCMD)
+LTDEPENDENCIES = $(LIBXFS) $(LIBXLOG) $(LIBXCMD)
 LLDFLAGS = -static-libtool-libs
 
 default: depend $(LTCOMMAND)
diff --git a/repair/phase1.c b/repair/phase1.c
index 126d0b3..c27033d 100644
--- a/repair/phase1.c
+++ b/repair/phase1.c
@@ -21,6 +21,7 @@
 #include "agheader.h"
 #include "protos.h"
 #include "err_protos.h"
+#include "libxcmd.h"
 
 static void
 no_sb(void)
@@ -47,6 +48,9 @@ alloc_ag_buf(int size)
  */
 #define MAX_SECTSIZE		(512 * 1024)
 
+extern libxfs_init_t x;
+
+
 /* ARGSUSED */
 void
 phase1(xfs_mount_t *mp)
@@ -54,6 +58,10 @@ phase1(xfs_mount_t *mp)
 	xfs_sb_t		*sb;
 	char			*ag_bp;
 	int			rval;
+	int			blocklog;
+	__uint64_t		agcount;
+	__uint64_t		agsize;
+	__uint64_t		skipsize;
 
 	do_log(_("Phase 1 - find and verify superblock...\n"));
 
@@ -65,6 +73,18 @@ phase1(xfs_mount_t *mp)
 	lost_quotas = 0;
 
 	/*
+	 * divine the geometry ;)
+	 */
+	blocklog = guess_default_geometry(&agsize, &agcount, x);
+
+	/*
+	 * use found ag geometry to quickly find secondary sb
+	 */
+	skipsize = agsize << blocklog;
+	do_log("agsize = %d  agcount = %d  skipsize = %d\n",
+	       (int)agsize, (int)agcount, (int)skipsize);
+
+	/*
 	 * get AG 0 into ag header buf
 	 */
 	ag_bp = alloc_ag_buf(MAX_SECTSIZE);
@@ -80,14 +100,15 @@ phase1(xfs_mount_t *mp)
 	if (rval != XR_OK)  {
 		do_warn(_("bad primary superblock - %s !!!\n"),
 			err_string(rval));
-		if (!find_secondary_sb(sb))
+
+		if (!find_secondary_sb(sb, skipsize))
 			no_sb();
 		primary_sb_modified = 1;
 	} else if ((rval = verify_set_primary_sb(sb, 0,
 					&primary_sb_modified)) != XR_OK)  {
 		do_warn(_("couldn't verify primary superblock - %s !!!\n"),
 			err_string(rval));
-		if (!find_secondary_sb(sb))
+		if (!find_secondary_sb(sb, skipsize))
 			no_sb();
 		primary_sb_modified = 1;
 	}
diff --git a/repair/protos.h b/repair/protos.h
index 9d5a2a6..d96373e 100644
--- a/repair/protos.h
+++ b/repair/protos.h
@@ -31,7 +31,7 @@ int	get_sb(xfs_sb_t			*sbp,
 void	write_primary_sb(xfs_sb_t	*sbp,
 			int		size);
 
-int	find_secondary_sb(xfs_sb_t	*sb);
+int	find_secondary_sb(xfs_sb_t	*sb, __uint64_t skipsize);
 
 struct fs_geometry;
 void	get_sb_geometry(struct fs_geometry	*geo,
diff --git a/repair/sb.c b/repair/sb.c
index 4eef14a..4386479 100644
--- a/repair/sb.c
+++ b/repair/sb.c
@@ -87,8 +87,7 @@ copy_sb(xfs_sb_t *source, xfs_sb_t *dest)
 /*
  * find a secondary superblock, copy it into the sb buffer
  */
-int
-find_secondary_sb(xfs_sb_t *rsb)
+static int __find_secondary_sb(xfs_sb_t *rsb, __uint64_t skipsize )
 {
 	xfs_off_t	off;
 	xfs_sb_t	*sb;
@@ -101,7 +100,6 @@ find_secondary_sb(xfs_sb_t *rsb)
 	int		bsize;
 
 	do_warn(_("\nattempting to find secondary superblock...\n"));
-
 	sb = (xfs_sb_t *)memalign(libxfs_device_alignment(), BSIZE);
 	if (!sb) {
 		do_error(
@@ -117,7 +115,7 @@ find_secondary_sb(xfs_sb_t *rsb)
 	/*
 	 * skip first sector since we know that's bad
 	 */
-	for (done = 0, off = XFS_AG_MIN_BYTES; !done ; off += bsize)  {
+	for (done = 0, off = skipsize; !done ; off += bsize)  {
 		/*
 		 * read disk 1 MByte at a time.
 		 */
@@ -130,7 +128,6 @@ find_secondary_sb(xfs_sb_t *rsb)
 		}
 
 		do_warn(".");
-
 		/*
 		 * check the buffer 512 bytes at a time since
 		 * we don't know how big the sectors really are.
@@ -164,11 +161,29 @@ find_secondary_sb(xfs_sb_t *rsb)
 			}
 		}
 	}
-
 	free(sb);
 	return(retval);
 }
 
+int
+find_secondary_sb(xfs_sb_t *rsb, __uint64_t skipsize)
+{
+	int		retval;
+
+	/*
+	 * Attempt to find secondary sb with a coarse approach,
+	 * using a large skipsize (agsize in bytes). Failing that,
+	 * fallback to the fine-grained approach using min agsize.
+	 */
+	retval = __find_secondary_sb(rsb, skipsize);
+	if (!retval)
+		/*
+		 * fallback: use minimum agsize for skipsize
+		 */
+		retval = __find_secondary_sb(rsb, XFS_AG_MIN_BYTES);
+	return(retval);
+}
+
 /*
  * Calculate what the inode alignment field ought to be based on internal
  * superblock info and determine if it is valid.
-- 
2.5.0

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