From 52dc121c412de9c1cc3058d782b949dc7b25dc3e Mon Sep 17 00:00:00 2001
From: Soumya Koduri <[email protected]>
Date: Thu, 25 Jul 2019 12:56:12 +0530
Subject: [PATCH 264/265] gfapi: Fix deadlock while processing upcall

As mentioned in bug1733166, there could be potential deadlock
while processing upcalls depending on how each xlator choose
to act on it. The right way of fixing such issues
is to change rpc callback communication process.
- https://github.com/gluster/glusterfs/issues/697

Till then, making changes in gfapi layer to avoid any I/O
processing.

This is backport of below mainline patch
> https://review.gluster.org/#/c/glusterfs/+/23108/
> bz#1733166
> https://review.gluster.org/#/c/glusterfs/+/23107/ (release-6)

Change-Id: I2079e95339e5d761d5060707f4555cfacab95c83
fixes: bz#1733520
Signed-off-by: Soumya Koduri <[email protected]>
Reviewed-on: https://code.engineering.redhat.com/gerrit/177675
Tested-by: RHGS Build Bot <[email protected]>
Reviewed-by: Sunil Kumar Heggodu Gopala Acharya <[email protected]>
---
 api/src/glfs-fops.c | 164 +++++++++++++++++++++++++++++++++++++++++-----------
 1 file changed, 131 insertions(+), 33 deletions(-)

diff --git a/api/src/glfs-fops.c b/api/src/glfs-fops.c
index 396f18c..e6adea5 100644
--- a/api/src/glfs-fops.c
+++ b/api/src/glfs-fops.c
@@ -34,7 +34,7 @@
 
 struct upcall_syncop_args {
     struct glfs *fs;
-    struct glfs_upcall *up_arg;
+    struct gf_upcall upcall_data;
 };
 
 #define READDIRBUF_SIZE (sizeof(struct dirent) + GF_NAME_MAX + 1)
@@ -5716,8 +5716,28 @@ out:
 static int
 upcall_syncop_args_free(struct upcall_syncop_args *args)
 {
-    if (args && args->up_arg)
-        GLFS_FREE(args->up_arg);
+    dict_t *dict = NULL;
+    struct gf_upcall *upcall_data = NULL;
+
+    if (args) {
+        upcall_data = &args->upcall_data;
+        switch (upcall_data->event_type) {
+            case GF_UPCALL_CACHE_INVALIDATION:
+                dict = ((struct gf_upcall_cache_invalidation *)(upcall_data
+                                                                    ->data))
+                           ->dict;
+                break;
+            case GF_UPCALL_RECALL_LEASE:
+                dict = ((struct gf_upcall_recall_lease *)(upcall_data->data))
+                           ->dict;
+                break;
+        }
+        if (dict)
+            dict_unref(dict);
+
+        GF_FREE(upcall_data->client_uid);
+        GF_FREE(upcall_data->data);
+    }
     GF_FREE(args);
     return 0;
 }
@@ -5727,14 +5747,7 @@ glfs_upcall_syncop_cbk(int ret, call_frame_t *frame, void *opaque)
 {
     struct upcall_syncop_args *args = opaque;
 
-    /* Here we not using upcall_syncop_args_free as application
-     * will be cleaning up the args->up_arg using glfs_free
-     * post processing upcall.
-     */
-    if (ret) {
-        upcall_syncop_args_free(args);
-    } else
-        GF_FREE(args);
+    (void)upcall_syncop_args_free(args);
 
     return 0;
 }
@@ -5743,29 +5756,17 @@ static int
 glfs_cbk_upcall_syncop(void *opaque)
 {
     struct upcall_syncop_args *args = opaque;
+    struct gf_upcall *upcall_data = NULL;
     struct glfs_upcall *up_arg = NULL;
     struct glfs *fs;
+    int ret = -1;
 
     fs = args->fs;
-    up_arg = args->up_arg;
-
-    if (fs->up_cbk && up_arg) {
-        (fs->up_cbk)(up_arg, fs->up_data);
-        return 0;
-    }
-
-    return -1;
-}
+    upcall_data = &args->upcall_data;
 
-static struct upcall_syncop_args *
-upcall_syncop_args_init(struct glfs *fs, struct gf_upcall *upcall_data)
-{
-    struct upcall_syncop_args *args = NULL;
-    int ret = -1;
-    struct glfs_upcall *up_arg = NULL;
-
-    if (!fs || !upcall_data)
+    if (!upcall_data) {
         goto out;
+    }
 
     up_arg = GLFS_CALLOC(1, sizeof(struct gf_upcall), glfs_release_upcall,
                          glfs_mt_upcall_entry_t);
@@ -5795,6 +5796,8 @@ upcall_syncop_args_init(struct glfs *fs, struct gf_upcall *upcall_data)
     if (up_arg->reason == GLFS_UPCALL_EVENT_NULL) {
         gf_msg(THIS->name, GF_LOG_DEBUG, errno, API_MSG_INVALID_ENTRY,
                "Upcall_EVENT_NULL received. Skipping it.");
+        ret = 0;
+        GLFS_FREE(up_arg);
         goto out;
     } else if (ret) {
         gf_msg(THIS->name, GF_LOG_ERROR, errno, API_MSG_INVALID_ENTRY,
@@ -5802,6 +5805,85 @@ upcall_syncop_args_init(struct glfs *fs, struct gf_upcall *upcall_data)
         goto out;
     }
 
+    if (fs->up_cbk && up_arg)
+        (fs->up_cbk)(up_arg, fs->up_data);
+
+    /* application takes care of calling glfs_free on up_arg post
+     * their processing */
+
+out:
+    return ret;
+}
+
+static struct gf_upcall_cache_invalidation *
+gf_copy_cache_invalidation(struct gf_upcall_cache_invalidation *src)
+{
+    struct gf_upcall_cache_invalidation *dst = NULL;
+
+    if (!src)
+        goto out;
+
+    dst = GF_CALLOC(1, sizeof(struct gf_upcall_cache_invalidation),
+                    glfs_mt_upcall_entry_t);
+
+    if (!dst) {
+        gf_msg(THIS->name, GF_LOG_ERROR, ENOMEM, API_MSG_ALLOC_FAILED,
+               "Upcall entry allocation failed.");
+        goto out;
+    }
+
+    dst->flags = src->flags;
+    dst->expire_time_attr = src->expire_time_attr;
+    dst->stat = src->stat;
+    dst->p_stat = src->p_stat;
+    dst->oldp_stat = src->oldp_stat;
+
+    if (src->dict)
+        dst->dict = dict_copy_with_ref(src->dict, NULL);
+
+    return dst;
+out:
+    return NULL;
+}
+
+static struct gf_upcall_recall_lease *
+gf_copy_recall_lease(struct gf_upcall_recall_lease *src)
+{
+    struct gf_upcall_recall_lease *dst = NULL;
+
+    if (!src)
+        goto out;
+
+    dst = GF_CALLOC(1, sizeof(struct gf_upcall_recall_lease),
+                    glfs_mt_upcall_entry_t);
+
+    if (!dst) {
+        gf_msg(THIS->name, GF_LOG_ERROR, ENOMEM, API_MSG_ALLOC_FAILED,
+               "Upcall entry allocation failed.");
+        goto out;
+    }
+
+    dst->lease_type = src->lease_type;
+    memcpy(dst->tid, src->tid, 16);
+
+    if (src->dict)
+        dst->dict = dict_copy_with_ref(src->dict, NULL);
+
+    return dst;
+out:
+    return NULL;
+}
+
+static struct upcall_syncop_args *
+upcall_syncop_args_init(struct glfs *fs, struct gf_upcall *upcall_data)
+{
+    struct upcall_syncop_args *args = NULL;
+    int ret = -1;
+    struct gf_upcall *t_data = NULL;
+
+    if (!fs || !upcall_data)
+        goto out;
+
     args = GF_CALLOC(1, sizeof(struct upcall_syncop_args),
                      glfs_mt_upcall_entry_t);
     if (!args) {
@@ -5819,15 +5901,31 @@ upcall_syncop_args_init(struct glfs *fs, struct gf_upcall *upcall_data)
      * notification without taking any lock/ref.
      */
     args->fs = fs;
-    args->up_arg = up_arg;
+    t_data = &(args->upcall_data);
+    t_data->client_uid = gf_strdup(upcall_data->client_uid);
 
-    /* application takes care of calling glfs_free on up_arg post
-     * their processing */
+    gf_uuid_copy(t_data->gfid, upcall_data->gfid);
+    t_data->event_type = upcall_data->event_type;
+
+    switch (t_data->event_type) {
+        case GF_UPCALL_CACHE_INVALIDATION:
+            t_data->data = gf_copy_cache_invalidation(
+                (struct gf_upcall_cache_invalidation *)upcall_data->data);
+            break;
+        case GF_UPCALL_RECALL_LEASE:
+            t_data->data = gf_copy_recall_lease(
+                (struct gf_upcall_recall_lease *)upcall_data->data);
+            break;
+    }
+
+    if (!t_data->data)
+        goto out;
 
     return args;
 out:
-    if (up_arg) {
-        GLFS_FREE(up_arg);
+    if (ret) {
+        GF_FREE(args->upcall_data.client_uid);
+        GF_FREE(args);
     }
 
     return NULL;
-- 
1.8.3.1