[Devel] [PATCH RHEL7 COMMIT] fs/fuse kio_pcs: protect valid_for_truncate() by m->lock's

[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.vz7.72.15
------>
commit f528febb7ad631868854baf2e1dc5211baef0ecc
Author: Pavel Butsykin <pbutsykin at virtuozzo.com>
Date:   Wed Oct 31 16:02:49 2018 +0300

    fs/fuse kio_pcs: protect valid_for_truncate() by m->lock's
    
    Access to m->state can be carried out only under m->lock.
    
    This patch protects valid_for_truncate() by m->lock's and thereby fixes
    unlocked access to m->state in process_ireq_truncate().
    
    Signed-off-by: Pavel Butsykin <pbutsykin at virtuozzo.com>
    Reviewed-by: Kirill Tkhai <ktkhai at virtuozzo.com>
    
    =====================
    Patchset description:
    
    FUSE KIO: Mapping truncate fixes
    
    https://jira.sw.ru/browse/PSBM-89539
---
 fs/fuse/kio/pcs/pcs_map.c | 10 +++++++---
 1 file changed, 7 insertions(+), 3 deletions(-)

diff --git a/fs/fuse/kio/pcs/pcs_map.c b/fs/fuse/kio/pcs/pcs_map.c
index 73808dffb8df..81a1a2a62ca4 100644
--- a/fs/fuse/kio/pcs/pcs_map.c
+++ b/fs/fuse/kio/pcs/pcs_map.c
@@ -2354,12 +2354,16 @@ void map_submit(struct pcs_map_entry * m, struct pcs_int_request *ireq)
 
 static int valid_for_truncate(struct pcs_map_entry * m, struct pcs_int_request *ireq)
 {
+	spin_lock(&m->lock);
+
 	/* This weird test means that map is valid, but points to a hole. In this case
 	 * truncate is noop.
 	 */
 	if ((m->state & (PCS_MAP_ERROR|PCS_MAP_RESOLVING|PCS_MAP_NEW|PCS_MAP_READABLE)) ==
-	    (PCS_MAP_NEW|PCS_MAP_READABLE))
+	    (PCS_MAP_NEW|PCS_MAP_READABLE)) {
+		spin_unlock(&m->lock);
 		return 1;
+	}
 
 	/* If we already have valid map, remember its version
 	 * and switch to the next phase: invalidation and requesting
@@ -2371,6 +2375,8 @@ static int valid_for_truncate(struct pcs_map_entry * m, struct pcs_int_request *
 		ireq->truncreq.version = m->version;
 	}
 	/* Otherwise lookup valid map first. */
+	spin_unlock(&m->lock);
+
 	return 0;
 }
 
@@ -2495,10 +2501,8 @@ noinline void pcs_mapping_truncate(struct pcs_int_request *ireq, u64 old_size)
 	if (m == NULL)
 		queue = 1;
 	else {
-		spin_lock(&m->lock);
 		if (!valid_for_truncate(m, ireq))
 			queue = 1;
-		spin_unlock(&m->lock);
 	}
 
 	if (queue) {