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lvmetad: Fix a possible race in remove_metadata.

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All operations on shared hash tables need to be protected by mutexes. Moreover,
lookup and subsequent key removal need to happen atomically, to avoid races (and
possible double free-ing) between multiple threads trying to manipulate the same
VG.
This commit is contained in:
Petr Rockai
2012-12-17 00:43:18 +01:00
parent fae1a611d2
commit 5294a6f77a
1 changed files with 9 additions and 5 deletions
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14
daemons/lvmetad/lvmetad-core.c
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@ -601,19 +601,23 @@ static int remove_metadata(lvmetad_state *s, const char *vgid, int update_pvids)
lock_vgid_to_metadata(s); lock_vgid_to_metadata(s);
old = dm_hash_lookup(s->vgid_to_metadata, vgid); old = dm_hash_lookup(s->vgid_to_metadata, vgid);
oldname = dm_hash_lookup(s->vgid_to_vgname, vgid); oldname = dm_hash_lookup(s->vgid_to_vgname, vgid);
unlock_vgid_to_metadata(s);
if (!old) if (!old) {
unlock_vgid_to_metadata(s);
return 0; return 0;
}
assert(oldname); assert(oldname);
if (update_pvids)
/* FIXME: What should happen when update fails */
update_pvid_to_vgid(s, old, "#orphan", 0);
/* need to update what we have since we found a newer version */ /* need to update what we have since we found a newer version */
dm_hash_remove(s->vgid_to_metadata, vgid); dm_hash_remove(s->vgid_to_metadata, vgid);
dm_hash_remove(s->vgid_to_vgname, vgid); dm_hash_remove(s->vgid_to_vgname, vgid);
dm_hash_remove(s->vgname_to_vgid, oldname); dm_hash_remove(s->vgname_to_vgid, oldname);
unlock_vgid_to_metadata(s);
if (update_pvids)
/* FIXME: What should happen when update fails */
update_pvid_to_vgid(s, old, "#orphan", 0);
dm_config_destroy(old); dm_config_destroy(old);
return 1; return 1;
} }