From 30cbdf8c06145a0c290da42ecc0a7eae928200b7 Mon Sep 17 00:00:00 2001

From: Xavi Hernandez <xhernandez@redhat.com>

Date: Sun, 8 Mar 2020 18:36:45 +0100

Subject: [PATCH 374/375] open-behind: fix missing fd reference

Open behind was not keeping any reference on fd's pending to be

opened. This makes it possible that a concurrent close and en entry

fop (unlink, rename, ...) caused destruction of the fd while it

was still being used.

Upstream patch:

> Upstream patch link: https://review.gluster.org/c/glusterfs/+/24204

> Change-Id: Ie9e992902cf2cd7be4af1f8b4e57af9bd6afd8e9

> Fixes: bz#1810934

> Signed-off-by: Xavi Hernandez <xhernandez@redhat.com>

Change-Id: Ie9e992902cf2cd7be4af1f8b4e57af9bd6afd8e9

BUG: 1830713

Signed-off-by: Xavi Hernandez <xhernandez@redhat.com>

Reviewed-on: https://code.engineering.redhat.com/gerrit/199714

Tested-by: RHGS Build Bot <nigelb@redhat.com>

Reviewed-by: Sunil Kumar Heggodu Gopala Acharya <sheggodu@redhat.com>

---

 xlators/performance/open-behind/src/open-behind.c | 27 ++++++++++++++---------

 1 file changed, 16 insertions(+), 11 deletions(-)

diff --git a/xlators/performance/open-behind/src/open-behind.c b/xlators/performance/open-behind/src/open-behind.c

index 268c717..14ebc12 100644

--- a/xlators/performance/open-behind/src/open-behind.c

+++ b/xlators/performance/open-behind/src/open-behind.c

@@ -206,8 +206,13 @@ ob_fd_free(ob_fd_t *ob_fd)

     if (ob_fd->xdata)

         dict_unref(ob_fd->xdata);

-    if (ob_fd->open_frame)

+    if (ob_fd->open_frame) {

+        /* If we sill have a frame it means that background open has never

+         * been triggered. We need to release the pending reference. */

+        fd_unref(ob_fd->fd);

+

         STACK_DESTROY(ob_fd->open_frame->root);

+    }

     GF_FREE(ob_fd);

 }

@@ -297,6 +302,7 @@ ob_wake_cbk(call_frame_t *frame, void *cookie, xlator_t *this, int op_ret,

             call_resume(stub);

     }

+    /* The background open is completed. We can release the 'fd' reference. */

     fd_unref(fd);

     STACK_DESTROY(frame->root);

@@ -331,7 +337,9 @@ ob_fd_wake(xlator_t *this, fd_t *fd, ob_fd_t *ob_fd)

     }

     if (frame) {

-        frame->local = fd_ref(fd);

+        /* We don't need to take a reference here. We already have a reference

+         * while the open is pending. */

+        frame->local = fd;

         STACK_WIND(frame, ob_wake_cbk, FIRST_CHILD(this),

                    FIRST_CHILD(this)->fops->open, &ob_fd->loc, ob_fd->flags, fd,

@@ -345,15 +353,12 @@ void

 ob_inode_wake(xlator_t *this, struct list_head *ob_fds)

 {

     ob_fd_t *ob_fd = NULL, *tmp = NULL;

-    fd_t *fd = NULL;

     if (!list_empty(ob_fds)) {

         list_for_each_entry_safe(ob_fd, tmp, ob_fds, ob_fds_on_inode)

         {

             ob_fd_wake(this, ob_fd->fd, ob_fd);

-            fd = ob_fd->fd;

             ob_fd_free(ob_fd);

-            fd_unref(fd);

         }

     }

 }

@@ -365,7 +370,7 @@ ob_fd_copy(ob_fd_t *src, ob_fd_t *dst)

     if (!src || !dst)

         goto out;

-    dst->fd = __fd_ref(src->fd);

+    dst->fd = src->fd;

     dst->loc.inode = inode_ref(src->loc.inode);

     gf_uuid_copy(dst->loc.gfid, src->loc.gfid);

     dst->flags = src->flags;

@@ -509,7 +514,6 @@ ob_open_behind(call_frame_t *frame, xlator_t *this, loc_t *loc, int flags,

     ob_fd->ob_inode = ob_inode;

-    /* don't do fd_ref, it'll cause leaks */

     ob_fd->fd = fd;

     ob_fd->open_frame = copy_frame(frame);

@@ -539,15 +543,16 @@ ob_open_behind(call_frame_t *frame, xlator_t *this, loc_t *loc, int flags,

     }

     UNLOCK(&fd->inode->lock);

-    if (!open_in_progress && !unlinked) {

-        fd_ref(fd);

+    /* We take a reference while the background open is pending or being

+     * processed. If we finally wind the request in the foreground, then

+     * ob_fd_free() will take care of this additional reference. */

+    fd_ref(fd);

+    if (!open_in_progress && !unlinked) {

         STACK_UNWIND_STRICT(open, frame, 0, 0, fd, xdata);

         if (!conf->lazy_open)

             ob_fd_wake(this, fd, NULL);

-

-        fd_unref(fd);

     } else {

         ob_fd_free(ob_fd);

         STACK_WIND(frame, default_open_cbk, FIRST_CHILD(this),

-- 

1.8.3.1