On 2/15/16 11:00 AM, Bill O'Donnell wrote:
> xfs_repair: new secondary superblock search method
>
> 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.
>
> version history:
> ----
> v1: http://oss.sgi.com/archives/xfs/2016-02/msg00304.html
> v2: patch 2 whitespace fixups
> v3: patch 2 correct functionality; style fixups
> v4: patch 1,2 properly see to style and whitespace fixups
> v5: patch 2 move guess_default_geometry() to sb.c plus
> very minor style/whitespace fixups.
> ----
>
> Signed-off-by: Bill O'Donnell <billodo@xxxxxxxxxx>
Looks good to me, thanks Bill!
Reviewed-by: Eric Sandeen <sandeen@xxxxxxxxxx>
> ---
> Makefile | 2 +-
> repair/Makefile | 4 ++--
> repair/sb.c | 72
> +++++++++++++++++++++++++++++++++++++++++++++++++++++----
> 3 files changed, 70 insertions(+), 8 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/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/sb.c b/repair/sb.c
> index 4eef14a..7e4708c 100644
> --- a/repair/sb.c
> +++ b/repair/sb.c
> @@ -17,6 +17,7 @@
> */
>
> #include "libxfs.h"
> +#include "libxcmd.h"
> #include "libxlog.h"
> #include "agheader.h"
> #include "globals.h"
> @@ -85,10 +86,15 @@ copy_sb(xfs_sb_t *source, xfs_sb_t *dest)
> }
>
> /*
> - * find a secondary superblock, copy it into the sb buffer
> + * find a secondary superblock, copy it into the sb buffer.
> + * start is the point to begin reading BSIZE bytes.
> + * skip contains a byte-count of how far to advance for next read.
> */
> -int
> -find_secondary_sb(xfs_sb_t *rsb)
> +static int
> +__find_secondary_sb(
> + xfs_sb_t *rsb,
> + __uint64_t start,
> + __uint64_t skip)
> {
> xfs_off_t off;
> xfs_sb_t *sb;
> @@ -117,7 +123,7 @@ 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 = start; !done ; off += skip) {
> /*
> * read disk 1 MByte at a time.
> */
> @@ -166,7 +172,63 @@ find_secondary_sb(xfs_sb_t *rsb)
> }
>
> free(sb);
> - return(retval);
> + return retval;
> +}
> +
> +static 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;
> + dblocks = x->dsize >> (blocklog - BBSHIFT);
> + calc_default_ag_geometry(blocklog, dblocks, multidisk,
> + agsize, agcount);
> +
> + return blocklog;
> +}
> +
> +int
> +find_secondary_sb(xfs_sb_t *rsb)
> +{
> + int retval;
> + __uint64_t agcount;
> + __uint64_t agsize;
> + __uint64_t skip;
> + int blocklog;
> +
> + /*
> + * Attempt to find secondary sb with a coarse approach.
> + * Failing that, fallback to a fine-grained approach.
> + */
> + blocklog = guess_default_geometry(&agsize, &agcount, &x);
> +
> + /*
> + * use found ag geometry to quickly find secondary sb
> + */
> + skip = agsize << blocklog;
> + retval = __find_secondary_sb(rsb, skip, skip);
> + if (!retval) {
> + /*
> + * fallback: Start at min agsize and scan all blocks
> + */
> + retval = __find_secondary_sb(rsb, XFS_AG_MIN_BYTES, BSIZE);
> + }
> + return retval;
> }
>
> /*
>
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