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[v20,01/71] libceph: add spinlock around osd->o_requests

Message ID 20230613052424.254540-2-xiubli@redhat.com
State New
Headers show
Series ceph+fscrypt: full support | expand

Commit Message

Xiubo Li June 13, 2023, 5:23 a.m. UTC 
From: Jeff Layton <jlayton@kernel.org>

In a later patch, we're going to need to search for a request in
the rbtree, but taking the o_mutex is inconvenient as we already
hold the con mutex at the point where we need it.

Add a new spinlock that we take when inserting and erasing entries from
the o_requests tree. Search of the rbtree can be done with either the
mutex or the spinlock, but insertion and removal requires both.

Tested-by: Luís Henriques <lhenriques@suse.de>
Tested-by: Venky Shankar <vshankar@redhat.com>
Reviewed-by: Luís Henriques <lhenriques@suse.de>
Reviewed-by: Xiubo Li <xiubli@redhat.com>
Signed-off-by: Jeff Layton <jlayton@kernel.org>
---
 include/linux/ceph/osd_client.h | 8 +++++++-
 net/ceph/osd_client.c           | 5 +++++
 2 files changed, 12 insertions(+), 1 deletion(-)
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Patch

diff --git a/include/linux/ceph/osd_client.h b/include/linux/ceph/osd_client.h
index fb6be72104df..92addef18738 100644
--- a/include/linux/ceph/osd_client.h
+++ b/include/linux/ceph/osd_client.h
@@ -29,7 +29,12 @@  typedef void (*ceph_osdc_callback_t)(struct ceph_osd_request *);
 
 #define CEPH_HOMELESS_OSD	-1
 
-/* a given osd we're communicating with */
+/*
+ * A given osd we're communicating with.
+ *
+ * Note that the o_requests tree can be searched while holding the "lock" mutex
+ * or the "o_requests_lock" spinlock. Insertion or removal requires both!
+ */
 struct ceph_osd {
 	refcount_t o_ref;
 	struct ceph_osd_client *o_osdc;
@@ -37,6 +42,7 @@  struct ceph_osd {
 	int o_incarnation;
 	struct rb_node o_node;
 	struct ceph_connection o_con;
+	spinlock_t o_requests_lock;
 	struct rb_root o_requests;
 	struct rb_root o_linger_requests;
 	struct rb_root o_backoff_mappings;
diff --git a/net/ceph/osd_client.c b/net/ceph/osd_client.c
index 11c04e7d928e..a827995faba7 100644
--- a/net/ceph/osd_client.c
+++ b/net/ceph/osd_client.c
@@ -1177,6 +1177,7 @@  static void osd_init(struct ceph_osd *osd)
 {
 	refcount_set(&osd->o_ref, 1);
 	RB_CLEAR_NODE(&osd->o_node);
+	spin_lock_init(&osd->o_requests_lock);
 	osd->o_requests = RB_ROOT;
 	osd->o_linger_requests = RB_ROOT;
 	osd->o_backoff_mappings = RB_ROOT;
@@ -1406,7 +1407,9 @@  static void link_request(struct ceph_osd *osd, struct ceph_osd_request *req)
 		atomic_inc(&osd->o_osdc->num_homeless);
 
 	get_osd(osd);
+	spin_lock(&osd->o_requests_lock);
 	insert_request(&osd->o_requests, req);
+	spin_unlock(&osd->o_requests_lock);
 	req->r_osd = osd;
 }
 
@@ -1418,7 +1421,9 @@  static void unlink_request(struct ceph_osd *osd, struct ceph_osd_request *req)
 	     req, req->r_tid);
 
 	req->r_osd = NULL;
+	spin_lock(&osd->o_requests_lock);
 	erase_request(&osd->o_requests, req);
+	spin_unlock(&osd->o_requests_lock);
 	put_osd(osd);
 
 	if (!osd_homeless(osd))