From 952e2f20b5b7f292d040b0456988f2748e4a554f Mon Sep 17 00:00:00 2001 From: pjd Date: Sun, 18 Dec 2011 12:27:45 +0000 Subject: [PATCH] From time to time people report space map corruption resulting in panic (ss == NULL) on pool import. I had such a panic recently. With current version of ZFS it is still possible to import the pool in readonly mode and backup all the data, but in case it is impossible for some reason add tunable vfs.zfs.space_map_last_hope, which when set to '1' will tell ZFS to remove colliding range and retry. This seems to have worked for me, but I consider it highly risky to use. MFC after: 1 week --- .../opensolaris/uts/common/fs/zfs/space_map.c | 26 ++++++++++++++++++- 1 file changed, 25 insertions(+), 1 deletion(-) diff --git a/sys/cddl/contrib/opensolaris/uts/common/fs/zfs/space_map.c b/sys/cddl/contrib/opensolaris/uts/common/fs/zfs/space_map.c index 1ce7b2a3d466..a8df1c704607 100644 --- a/sys/cddl/contrib/opensolaris/uts/common/fs/zfs/space_map.c +++ b/sys/cddl/contrib/opensolaris/uts/common/fs/zfs/space_map.c @@ -29,6 +29,13 @@ #include #include +SYSCTL_DECL(_vfs_zfs); +static int space_map_last_hope; +TUNABLE_INT("vfs.zfs.space_map_last_hope", &space_map_last_hope); +SYSCTL_INT(_vfs_zfs, OID_AUTO, space_map_last_hope, CTLFLAG_RDTUN, + &space_map_last_hope, 0, + "If kernel panic in space_map code on pool import, import the pool in readonly mode and backup all your data before trying this option."); + /* * Space map routines. * NOTE: caller is responsible for all locking. @@ -93,7 +100,7 @@ space_map_add(space_map_t *sm, uint64_t start, uint64_t size) VERIFY(sm->sm_space + size <= sm->sm_size); VERIFY(P2PHASE(start, 1ULL << sm->sm_shift) == 0); VERIFY(P2PHASE(size, 1ULL << sm->sm_shift) == 0); - +again: ssearch.ss_start = start; ssearch.ss_end = end; ss = avl_find(&sm->sm_root, &ssearch, &where); @@ -104,6 +111,23 @@ space_map_add(space_map_t *sm, uint64_t start, uint64_t size) (longlong_t)start, (longlong_t)size); return; } + if (ss != NULL && space_map_last_hope) { + uint64_t sstart, ssize; + + if (ss->ss_start > start) + sstart = ss->ss_start; + else + sstart = start; + if (ss->ss_end > end) + ssize = end - sstart; + else + ssize = ss->ss_end - sstart; + ZFS_LOG(0, + "Removing colliding space_map range (start=%ju end=%ju). Good luck!", + (uintmax_t)sstart, (uintmax_t)(sstart + ssize)); + space_map_remove(sm, sstart, ssize); + goto again; + } /* Make sure we don't overlap with either of our neighbors */ VERIFY(ss == NULL);