From: liuh <liuhuan01@xxxxxxxxxx>
Recently, I was testing xfstests. When I run xfs/350 case, it always generate coredump during the process.
xfs_db -c "sb 0" -c "p agblocks" /dev/loop1
System will generate signal SIGFPE corrupt the process. And the stack as follow:
corrupt at: (*bpp)->b_pag = xfs_perag_get(btp->bt_mount, xfs_daddr_to_agno(btp->bt_mount, blkno)); in function libxfs_getbuf_flags
#0 libxfs_getbuf_flags
#1 libxfs_getbuf_flags
#2 libxfs_buf_read_map
#3 libxfs_buf_read
#4 libxfs_mount
#5 init
#6 main
The coredump was caused by the corrupt superblock metadata: (mp)->m_sb.sb_agblocks, it was 0.
In this case, user cannot run in expert mode also.
So, try to get agblocks from agf/agi 0, if agf/agi 0 length match, use it as agblocks.
If failed use the default geometry to calc agblocks.
Signed-off-by: liuh <liuhuan01@xxxxxxxxxx>
---
db/Makefile | 2 +-
db/init.c | 142 ++++++++++++++++++++++++++++++++++++++++++++++++++++
2 files changed, 143 insertions(+), 1 deletion(-)
diff --git a/db/Makefile b/db/Makefile
index 83389376..322d5617 100644
--- a/db/Makefile
+++ b/db/Makefile
@@ -68,7 +68,7 @@ CFILES = $(HFILES:.h=.c) \
LSRCFILES = xfs_admin.sh xfs_ncheck.sh xfs_metadump.sh
LLDLIBS = $(LIBXFS) $(LIBXLOG) $(LIBFROG) $(LIBUUID) $(LIBRT) $(LIBURCU) \
- $(LIBPTHREAD)
+ $(LIBPTHREAD) $(LIBBLKID)
LTDEPENDENCIES = $(LIBXFS) $(LIBXLOG) $(LIBFROG)
LLDFLAGS += -static-libtool-libs
diff --git a/db/init.c b/db/init.c
index cea25ae5..167bc777 100644
--- a/db/init.c
+++ b/db/init.c
@@ -38,6 +38,138 @@ usage(void)
exit(1);
}
+static void
+xfs_guess_default_ag_geometry(uint64_t *agsize, uint64_t *agcount, struct libxfs_init *x)
+{
+ struct fs_topology ft;
+ int blocklog;
+ uint64_t dblocks;
+ int multidisk;
+
+ fprintf(stderr, "Attempting to guess AG length from device geometry. This may not work.\n");
+
+ 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.data.swidth | ft.data.sunit;
+ dblocks = x->data.size >> (blocklog - BBSHIFT);
+ calc_default_ag_geometry(blocklog, dblocks, multidisk,
+ agsize, agcount);
+
+ if (*agsize >= XFS_MIN_AG_BLOCKS && *agsize <= XFS_MAX_AG_BLOCKS)
+ fprintf(stderr, "Guessed AG length is %lu blocks.\n", *agsize);
+}
+
+static xfs_agblock_t
+xfs_get_agblock_from_agf(struct xfs_mount *mp)
+{
+ xfs_agblock_t agblocks = NULLAGBLOCK;
+ int error;
+ struct xfs_buf *bp;
+ struct xfs_agf *agf;
+
+ error = -libxfs_buf_read_uncached(mp->m_ddev_targp,
+ XFS_AGF_DADDR(mp), 1, 0, &bp, NULL);
+ if (error) {
+ fprintf(stderr, "AGF 0 length recovery failed\n");
+ return NULLAGBLOCK;
+ }
+
+ agf = bp->b_addr;
+ if (be32_to_cpu(agf->agf_magicnum) == XFS_AGF_MAGIC)
+ agblocks = be32_to_cpu(agf->agf_length);
+
+ libxfs_buf_relse(bp);
+
+ if (agblocks != NULLAGBLOCK)
+ fprintf(stderr, "AGF 0 length %u blocks found.\n", agblocks);
+ else
+ fprintf(stderr, "AGF 0 length recovery failed.\n");
+
+ return agblocks;
+}
+
+static xfs_agblock_t
+xfs_get_agblock_from_agi(struct xfs_mount *mp)
+{
+ xfs_agblock_t agblocks = NULLAGBLOCK;
+ int error;
+ struct xfs_buf *bp;
+ struct xfs_agi *agi;
+
+ error = -libxfs_buf_read_uncached(mp->m_ddev_targp,
+ XFS_AGI_DADDR(mp), 1, 0, &bp, NULL);
+ if (error) {
+ fprintf(stderr, "AGI 0 length recovery failed\n");
+ return NULLAGBLOCK;
+ }
+
+
+ agi = bp->b_addr;
+ if (be32_to_cpu(agi->agi_magicnum) == XFS_AGI_MAGIC)
+ agblocks = be32_to_cpu(agi->agi_length);
+
+ libxfs_buf_relse(bp);
+
+ if (agblocks != NULLAGBLOCK)
+ fprintf(stderr, "AGI 0 length %u blocks found.\n", agblocks);
+ else
+ fprintf(stderr, "AGI 0 length recovery failed.\n");
+
+ return agblocks;
+}
+
+/*
+ * Try to get it from agf/agi length when primary superblock agblocks damaged.
+ * If agf matchs agi length, use it as agblocks, otherwise use the default geometry
+ * to calc agblocks
+ */
+static xfs_agblock_t
+xfs_try_get_agblocks(struct xfs_mount *mp, struct libxfs_init *x)
+{
+ xfs_agblock_t agblocks = NULLAGBLOCK;
+ xfs_agblock_t agblocks_agf, agblocks_agi;
+ uint64_t agsize, agcount;
+
+ fprintf(stderr, "Attempting recovery from AGF/AGI 0 metadata...\n");
+
+ agblocks_agf = xfs_get_agblock_from_agf(mp);
+ agblocks_agi = xfs_get_agblock_from_agi(mp);
+
+ if (agblocks_agf == agblocks_agi && agblocks_agf >= XFS_MIN_AG_BLOCKS && agblocks_agf <= XFS_MAX_AG_BLOCKS) {
+ fprintf(stderr, "AGF/AGI 0 length matches.\n");
+ fprintf(stderr, "Using %u blocks for superblock agblocks\n", agblocks_agf);
+ return agblocks_agf;
+ }
+
+ /* use default geometry to calc agblocks/agcount */
+ xfs_guess_default_ag_geometry(&agsize, &agcount, x);
+
+ /* choose the agblocks among agf/agi length and agsize */
+ if (agblocks_agf == agsize && agsize >= XFS_MIN_AG_BLOCKS && agsize <= XFS_MAX_AG_BLOCKS) {
+ fprintf(stderr, "Guessed AG matchs AGF length\n");
+ agblocks = agsize;
+ } else if (agblocks_agi == agsize && agsize >= XFS_MIN_AG_BLOCKS && agsize <= XFS_MAX_AG_BLOCKS) {
+ fprintf(stderr, "Guessed AG matchs AGI length\n");
+ agblocks = agsize;
+ } else if (agsize >= XFS_MIN_AG_BLOCKS && agsize <= XFS_MAX_AG_BLOCKS) {
+ fprintf(stderr, "Guessed AG does not match AGF/AGI 0 length.\n");
+ agblocks = agsize;
+ } else {
+ fprintf(stderr, "_(%s: device too small to hold a valid XFS filesystem)", progname);
+ exit(1);
+ }
+
+ fprintf(stderr, "Using %u blocks for superblock agblocks.\n", agblocks);
+
+ return agblocks;
+}
+
static void
init(
int argc,
@@ -129,6 +261,16 @@ init(
}
}
+ /* If sb_agblocks was damaged, try to get agblocks */
+ if (sbp->sb_agblocks < XFS_MIN_AG_BLOCKS || sbp->sb_agblocks > XFS_MAX_AG_BLOCKS) {
+ xfs_agblock_t agblocks;
+
+ fprintf(stderr, "Out of bounds superblock agblocks (%u) found.\n", sbp->sb_agblocks);
+
+ agblocks = xfs_try_get_agblocks(&xmount, &x);
+ sbp->sb_agblocks = agblocks;
+ }
+
agcount = sbp->sb_agcount;
mp = libxfs_mount(&xmount, sbp, &x, LIBXFS_MOUNT_DEBUGGER);
if (!mp) {
--
2.43.0
