@@ -124,6 +124,14 @@ struct lo_inode {
GHashTable *posix_locks; /* protected by lo_inode->plock_mutex */
mode_t filetype;
+
+ /*
+ * So we can detect crossmount roots
+ * (As such, this only needs to be valid for directories. Note
+ * that files can have multiple parents due to hard links, and so
+ * their parent_dev may fluctuate.)
+ */
+ dev_t parent_dev;
};
struct lo_cred {
@@ -821,6 +829,7 @@ static int lo_do_lookup(fuse_req_t req, fuse_ino_t parent, const char *name,
g_hash_table_insert(lo->inodes, &inode->key, inode);
pthread_mutex_unlock(&lo->mutex);
}
+ inode->parent_dev = dir->key.dev;
e->ino = inode->fuse_ino;
lo_inode_put(lo, &inode);
lo_inode_put(lo, &dir);
@@ -1047,6 +1056,14 @@ static void lo_link(fuse_req_t req, fuse_ino_t ino, fuse_ino_t parent,
fuse_log(FUSE_LOG_DEBUG, " %lli/%s -> %lli\n", (unsigned long long)parent,
name, (unsigned long long)e.ino);
+ /*
+ * No need to update inode->parent_dev, because
+ * (1) We cannot, the inode now has more than one parent,
+ * (2) Directories cannot have more than one parent, so link()
+ * does not work for them; but parent_dev only needs to be
+ * valid for directories.
+ */
+
fuse_reply_entry(req, &e);
lo_inode_put(lo, &parent_inode);
lo_inode_put(lo, &inode);
We want to detect mount points in the shared tree. We report them to the guest by setting the FUSE_ATTR_SUBMOUNT flag in fuse_attr.flags, but because the FUSE client will create a submount for every directory that has this flag set, we must do this only for the actual mount points. We can detect mount points by comparing a directory's st_dev with its parent's st_dev. To be able to do so, we need to store the parent's st_dev in the lo_inode object. Note that mount points need not necessarily be directories; a single file can be a mount point as well. However, for the sake of simplicity let us ignore any non-directory mount points for now. Signed-off-by: Max Reitz <mreitz@redhat.com> --- tools/virtiofsd/passthrough_ll.c | 17 +++++++++++++++++ 1 file changed, 17 insertions(+)