06f79675b7
VOP_RMDIR() is called with both parent and child directory vnodes locked. The relookup operation performed by the unionfs implementation may relock both vnodes. Accordingly, unionfs_relookup() drops the parent vnode lock, but the child vnode lock is never dropped. Although relookup() will very likely try to relock the child vnode which is already locked, in most cases this doesn't produce a deadlock because unionfs_lock() forces LK_CANRECURSE (!). However, relocking of the parent vnode while the child vnode remains locked effectively reverses the expected parent->child lock order, which can produce a deadlock e.g. in the presence of a concurrent unionfs_lookup() operation. Address the issue by dropping the child lock around the unionfs_relookup() call in unionfs_rmdir(). Reported by: pho Reviewed by: kib, markj Differential Revision: https://reviews.freebsd.org/D32986 |
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| .. | ||
| union_subr.c | ||
| union_vfsops.c | ||
| union_vnops.c | ||
| union.h | ||