ceph: allocate capsnap memory outside of ceph_queue_cap_snap()

This will reduce very possible but unnecessary frequently memory
allocate/free in this loop.

URL: https://tracker.ceph.com/issues/44100
Signed-off-by: Xiubo Li <xiubli@redhat.com>
Reviewed-by: Jeff Layton <jlayton@kernel.org>
Signed-off-by: Ilya Dryomov <idryomov@gmail.com>

diff --git a/fs/ceph/snap.c b/fs/ceph/snap.c
index cc9097c..b75dcc9 100644 (file)
--- a/fs/ceph/snap.c
+++ b/fs/ceph/snap.c
@@ -522,23 +522,15 @@ static bool has_new_snaps(struct ceph_snap_context *o,
  * Caller must hold snap_rwsem for read (i.e., the realm topology won't
  * change).
  */
-static void ceph_queue_cap_snap(struct ceph_inode_info *ci)
+static void ceph_queue_cap_snap(struct ceph_inode_info *ci,
+                               struct ceph_cap_snap **pcapsnap)
 {
        struct inode *inode = &ci->vfs_inode;
-       struct ceph_cap_snap *capsnap;
        struct ceph_snap_context *old_snapc, *new_snapc;
+       struct ceph_cap_snap *capsnap = *pcapsnap;
        struct ceph_buffer *old_blob = NULL;
        int used, dirty;
 
-       capsnap = kmem_cache_zalloc(ceph_cap_snap_cachep, GFP_NOFS);
-       if (!capsnap) {
-               pr_err("ENOMEM allocating ceph_cap_snap on %p\n", inode);
-               return;
-       }
-       capsnap->cap_flush.is_capsnap = true;
-       INIT_LIST_HEAD(&capsnap->cap_flush.i_list);
-       INIT_LIST_HEAD(&capsnap->cap_flush.g_list);
-
        spin_lock(&ci->i_ceph_lock);
        used = __ceph_caps_used(ci);
        dirty = __ceph_caps_dirty(ci);
@@ -595,9 +587,6 @@ static void ceph_queue_cap_snap(struct ceph_inode_info *ci)
             capsnap->need_flush ? "" : "no_flush");
        ihold(inode);
 
-       refcount_set(&capsnap->nref, 1);
-       INIT_LIST_HEAD(&capsnap->ci_item);
-
        capsnap->follows = old_snapc->seq;
        capsnap->issued = __ceph_caps_issued(ci, NULL);
        capsnap->dirty = dirty;
@@ -635,7 +624,7 @@ static void ceph_queue_cap_snap(struct ceph_inode_info *ci)
                /* note mtime, size NOW. */
                __ceph_finish_cap_snap(ci, capsnap);
        }
-       capsnap = NULL;
+       *pcapsnap = NULL;
        old_snapc = NULL;
 
 update_snapc:
@@ -651,8 +640,6 @@ update_snapc:
        spin_unlock(&ci->i_ceph_lock);
 
        ceph_buffer_put(old_blob);
-       if (capsnap)
-               kmem_cache_free(ceph_cap_snap_cachep, capsnap);
        ceph_put_snap_context(old_snapc);
 }
 
@@ -720,6 +707,7 @@ static void queue_realm_cap_snaps(struct ceph_snap_realm *realm)
 {
        struct ceph_inode_info *ci;
        struct inode *lastinode = NULL;
+       struct ceph_cap_snap *capsnap = NULL;
 
        dout("queue_realm_cap_snaps %p %llx inodes\n", realm, realm->ino);
 
@@ -731,12 +719,34 @@ static void queue_realm_cap_snaps(struct ceph_snap_realm *realm)
                spin_unlock(&realm->inodes_with_caps_lock);
                iput(lastinode);
                lastinode = inode;
-               ceph_queue_cap_snap(ci);
+
+               /*
+                * Allocate the capsnap memory outside of ceph_queue_cap_snap()
+                * to reduce very possible but unnecessary frequently memory
+                * allocate/free in this loop.
+                */
+               if (!capsnap) {
+                       capsnap = kmem_cache_zalloc(ceph_cap_snap_cachep, GFP_NOFS);
+                       if (!capsnap) {
+                               pr_err("ENOMEM allocating ceph_cap_snap on %p\n",
+                                      inode);
+                               return;
+                       }
+               }
+               capsnap->cap_flush.is_capsnap = true;
+               refcount_set(&capsnap->nref, 1);
+               INIT_LIST_HEAD(&capsnap->cap_flush.i_list);
+               INIT_LIST_HEAD(&capsnap->cap_flush.g_list);
+               INIT_LIST_HEAD(&capsnap->ci_item);
+
+               ceph_queue_cap_snap(ci, &capsnap);
                spin_lock(&realm->inodes_with_caps_lock);
        }
        spin_unlock(&realm->inodes_with_caps_lock);
        iput(lastinode);
 
+       if (capsnap)
+               kmem_cache_free(ceph_cap_snap_cachep, capsnap);
        dout("queue_realm_cap_snaps %p %llx done\n", realm, realm->ino);
 }