[Devel] [PATCH RHEL7 COMMIT] fuse kio: Use sio eof instead of parent to determ abort

[Konstantin Khorenko]

The commit is pushed to "branch-rh7-3.10.0-862.14.4.vz7.72.x-ovz" and will appear at https://src.openvz.org/scm/ovz/vzkernel.git
after rh7-3.10.0-862.14.4.vz7.72.9
------>
commit fb8a0a11992e4f8ab03b9601eb520e5749bbc73c
Author: Kirill Tkhai <ktkhai at virtuozzo.com>
Date:   Tue Oct 16 18:04:29 2018 +0300

    fuse kio: Use sio eof instead of parent to determ abort
    
    We can't just null sio->parent, since this is not synchronized
    with socket callbacks. They can already take this counter, and
    then delay for a while.
    
    This patch starts reworking of pcs_sockio and pcs_rpc destruction,
    and makes the parent pointer be nulled later. This will allow
    to take sio->parent refcounter for each sio in next patches
    and to keep parent alive till callbacks end.
    
    Signed-off-by: Kirill Tkhai <ktkhai at virtuozzo.com>
    Reviewed-by: Pavel Butsykin <pbutsykin at virtuozzo.com>
    
    =====================
    Patchset description:
    
    Order pcs_rpc and pcs_sockio destruction and close leaked socket
    
    https://pmc.acronis.com/browse/VSTOR-15305
    
    Ploop can asynchronously unmap regions by sending IOCB_CMD_UNMAP_ITER, but this
    command isn't quite correctly interpreted in Fuse. Moreover, in Fast-path mode,
    fallocate(FALLOC_FL_PUNCH_HOLE|FALLOC_FL_ZERO_RANGE) falls to fuse user daemon
    and it can lead to data corruption.
    
    Let's fix it.
    
    Kirill Tkhai (9):
          fuse kio: Use __maybe_unused
          fuse kio: Use sio eof instead of parent to determ abort
          fuse kio: Reorder callback assignment
          fuse kio: Add pcs_cleanup_wq
          fuse kio: Destroy rpc in work func
          fuse kio: Introduce pcs_sk_kick_queue()
          fuse kio: Dereference sk_user_data under rcu
          fuse kio: Fix rpc socket leak on rpc_abort()
          fuse kio: Hold pcs_rpc counter till sio may be freed
---
 fs/fuse/kio/pcs/pcs_rpc.c | 6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)

diff --git a/fs/fuse/kio/pcs/pcs_rpc.c b/fs/fuse/kio/pcs/pcs_rpc.c
index 92c0b78d6326..e7ae4bfd9feb 100644
--- a/fs/fuse/kio/pcs/pcs_rpc.c
+++ b/fs/fuse/kio/pcs/pcs_rpc.c
@@ -206,7 +206,7 @@ void rpc_abort(struct pcs_rpc * ep, int fatal, int error)
 		if (ep->gc)
 			list_lru_del(&ep->gc->lru, &ep->lru_link);
 
-		sio->parent = NULL;
+		sio->eof = NULL;
 		pcs_sock_error(sio, error);
 	}
 
@@ -332,7 +332,7 @@ static void rpc_eof_cb(struct pcs_sockio * sio)
 {
 	struct pcs_rpc * ep = sio->parent;
 
-	if (ep == NULL)
+	if (WARN_ON_ONCE(ep == NULL))
 		return;
 
 	/* Dead socket is finally closed, we could already open another one.
@@ -532,7 +532,7 @@ struct pcs_msg *rpc_get_hdr(struct pcs_sockio * sio, u32 *msg_size)
 	struct pcs_msg * msg;
 	void (*next_input)(struct pcs_msg *);
 
-	if (ep == NULL)
+	if (WARN_ON_ONCE(ep == NULL))
 		return NULL;
 
 	/* Fatal stream format error */