AUTOFS: remove all maps from hash if request for auto.master comes in

https://fedorahosted.org/sssd/ticket/1592

When a request for auto.master comes in, we need to remove all the maps
from the lookup hash table. We can't simply delete the maps, because
another request might be processing them, so instead the maps are
removed from the hash table, effectively becoming orphaned. The maps
will get freed when the timed destructor is invoked.

Author: jhrozek

src/responder/autofs/autofs_private.h

@@ -79,6 +79,8 @@ struct sss_cmd_table *get_autofs_cmds(void);
 void autofs_map_hash_delete_cb(hash_entry_t *item,
                                hash_destroy_enum deltype, void *pvt);
 
+errno_t autofs_orphan_maps(struct autofs_ctx *actx);
+
 enum sss_dp_autofs_type {
     SSS_DP_AUTOFS
 };

src/responder/autofs/autofssrv_cmd.c

@@ -90,6 +90,34 @@ autofs_setent_notify(struct autofs_map_ctx *map_ctx, errno_t ret)
     setent_notify(&map_ctx->reqs, ret);
 }
 
+errno_t
+autofs_orphan_maps(struct autofs_ctx *actx)
+{
+    int hret;
+    unsigned long mcount;
+    unsigned long i;
+    hash_key_t *maps;
+
+    if (!actx || !actx->maps) {
+        return EINVAL;
+    }
+
+    hret = hash_keys(actx->maps, &mcount, &maps);
+    if (hret != HASH_SUCCESS) {
+        return EIO;
+    }
+
+    for (i = 0; i < mcount; i++) {
+        hret = hash_delete(actx->maps, &maps[i]);
+        if (hret != HASH_SUCCESS) {
+            DEBUG(SSSDBG_MINOR_FAILURE, ("Could not delete key from hash\n"));
+            continue;
+        }
+    }
+
+    return EOK;
+}
+
 static errno_t
 get_autofs_map(struct autofs_ctx *actx,
                char *mapname,
@@ -369,6 +397,11 @@ set_autofs_map_lifetime(uint32_t lifetime,
     }
 }
 
+static errno_t
+setautomntent_get_autofs_map(struct autofs_ctx *actx,
+                             char *mapname,
+                             struct autofs_map_ctx **map);
+
 static struct tevent_req *
 setautomntent_send(TALLOC_CTX *mem_ctx,
                    const char *rawname,
@@ -442,7 +475,7 @@ setautomntent_send(TALLOC_CTX *mem_ctx,
     /* Is the result context already available?
      * Check for existing lookups for this map
      */
-    ret = get_autofs_map(actx, state->mapname, &state->map);
+    ret = setautomntent_get_autofs_map(actx, state->mapname, &state->map);
     if (ret == EOK) {
         /* Another process already requested this map
          * Check whether it's ready for processing.
@@ -558,6 +591,25 @@ setautomntent_send(TALLOC_CTX *mem_ctx,
     return req;
 }
 
+static errno_t
+setautomntent_get_autofs_map(struct autofs_ctx *actx,
+                             char *mapname,
+                             struct autofs_map_ctx **map)
+{
+    errno_t ret;
+
+    if (strcmp(mapname, "auto.master") == 0) {
+        /* Iterate over the hash and remove all maps */
+        ret = autofs_orphan_maps(actx);
+        if (ret != EOK) {
+            DEBUG(SSSDBG_MINOR_FAILURE, ("Could not remove existing maps from hash\n"));
+        }
+        return ENOENT;
+    }
+
+    return get_autofs_map(actx, mapname, map);
+}
+
 static errno_t
 lookup_automntmap_update_cache(struct setautomntent_lookup_ctx *lookup_ctx);
 
@@ -718,8 +770,10 @@ lookup_automntmap_update_cache(struct setautomntent_lookup_ctx *lookup_ctx)
     struct dp_callback_ctx *cb_ctx = NULL;
 
     if (dctx->map != NULL) {
-        cache_expire = ldb_msg_find_attr_as_uint64(dctx->map,
-                                                   SYSDB_CACHE_EXPIRE, 0);
+        if (strcmp(lookup_ctx->mapname, "auto.master") != 0) {
+            cache_expire = ldb_msg_find_attr_as_uint64(dctx->map,
+                                                       SYSDB_CACHE_EXPIRE, 0);
+        }
 
         /* if we have any reply let's check cache validity */
         ret = sss_cmd_check_cache(dctx->map, 0, cache_expire);