[libvirt] [PATCH 3/3] storage: Fix checking whether source filesystem is mounted

[Erik Skultety]

On Thu, Feb 09, 2017 at 06:05:41PM -0500, John Ferlan wrote:
> 
> 
> On 02/07/2017 09:16 AM, Erik Skultety wrote:
> > Right now, we use simple string comparison both on the source paths
> > (mount's output vs pool's source) and the target (mount's mnt_dir vs
> > pool's target). The problem are symlinks and mount indeed returns
> > symlinks in its output, e.g. /dev/mappper/lvm_symlink. The same goes for
> > the pool's source/target, so in order to successfully compare these two
> > replace plain string comparison with virFileComparePaths which will
> > resolve all symlinks and canonicalize the paths prior to comparison.
> > 
> > Resolves: https://bugzilla.redhat.com/show_bug.cgi?id=1417203
> > 
> > Signed-off-by: Erik Skultety <eskultet at redhat.com>
> > ---
> >  src/storage/storage_backend_fs.c | 12 ++++++++++--
> >  1 file changed, 10 insertions(+), 2 deletions(-)
> > 
> > diff --git a/src/storage/storage_backend_fs.c b/src/storage/storage_backend_fs.c
> > index fe4705b..fae1c03 100644
> > --- a/src/storage/storage_backend_fs.c
> > +++ b/src/storage/storage_backend_fs.c
> > @@ -301,6 +301,7 @@ virStorageBackendFileSystemIsMounted(virStoragePoolObjPtr pool)
> >      FILE *mtab;
> >      struct mntent ent;
> >      char buf[1024];
> > +    int rc1, rc2;
> >  
> >      if ((mtab = fopen(_PATH_MOUNTED, "r")) == NULL) {
> >          virReportSystemError(errno,
> > @@ -313,8 +314,15 @@ virStorageBackendFileSystemIsMounted(virStoragePoolObjPtr pool)
> >          if (!(src = virStorageBackendFileSystemGetPoolSource(pool)))
> >              goto cleanup;
> >  
> > -        if (STREQ(ent.mnt_dir, pool->def->target.path) &&
> > -            STREQ(ent.mnt_fsname, src)) {
> > +        /* compare both mount destinations and sources to be sure the mounted
> > +         * FS pool is really the one we're looking for
> > +         */
> > +        if ((rc1 = virFileComparePaths(ent.mnt_dir,
> > +                                       pool->def->target.path)) < 0 ||
> > +            (rc2 = virFileComparePaths(ent.mnt_fsname, src)) < 0)
> > +            goto cleanup;
> > +
> > +        if (rc1 == 0 && rc2 == 0) {
> 
> With changes to previous to return 1 on match, then this gets adjusted
> too...
> 
> ACK - I think you can alter this appropriately

Sure, thanks.

Erik

> 
> John
> >              ret = 1;
> >              goto cleanup;
> >          }
> > 
> 
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