[libvirt] [PATCH 2/3] qemuDomainGetPreservedMounts: Prune nested mount points

https://bugzilla.redhat.com/show_bug.cgi?id=1431112 There can be nested mount points. For instance /dev/shm/blah can be a mount point and /dev/shm too. It doesn't make much sense to return the former path because callers preserve the latter (and with that the former too). Therefore prune nested mount points. Signed-off-by: Michal Privoznik <mprivozn(a)redhat.com&gt; --- src/qemu/qemu_domain.c | 23 ++++++++++++++++++++++- 1 file changed, 22 insertions(+), 1 deletion(-) diff --git a/src/qemu/qemu_domain.c b/src/qemu/qemu_domain.c index 23b92606e..accf05a6f 100644 --- a/src/qemu/qemu_domain.c +++ b/src/qemu/qemu_domain.c @@ -7533,7 +7533,7 @@ qemuDomainGetPreservedMounts(virQEMUDriverConfigPtr cfg, size_t *ndevPath) { char **paths = NULL, **mounts = NULL; - size_t i, nmounts; + size_t i, j, nmounts; if (virFileGetMountSubtree(PROC_MOUNTS, "/dev", &mounts, &nmounts) < 0) @@ -7545,6 +7545,27 @@ qemuDomainGetPreservedMounts(virQEMUDriverConfigPtr cfg, return 0; } + /* There can be nested mount points. For instance + * /dev/shm/blah can be a mount point and /dev/shm too. It + * doesn't make much sense to return the former path because + * caller preserves the latter (and with that the former + * too). Therefore prune nested mount points. + * NB mounts[0] is "/dev". Should we start the outer loop + * from the beginning of the array all we'd be left with is + * just the first element. Think about it. + */ + for (i = 1; i < nmounts; i++) { + for (j = i + 1; j < nmounts;) { + if (STRPREFIX(mounts[j], mounts[i])) { + VIR_DEBUG("Dropping path %s because of %s", mounts[j], mounts[i]); + VIR_DELETE_ELEMENT(mounts, j, nmounts); + } else { + j++; + } + } + } + + if (VIR_ALLOC_N(paths, nmounts) < 0) goto error; -- 2.13.0