ceph: drop private list from remove_session_caps_cb

This function does a lot of list-shuffling with cap flushes, all to
avoid possibly freeing a slab allocation under spinlock (which is
totally ok).  Simplify the code by just detaching and freeing the cap
flushes in place.

Signed-off-by: Jeff Layton <jlayton@kernel.org>
Signed-off-by: Ilya Dryomov <idryomov@gmail.com>

diff --git a/fs/ceph/mds_client.c b/fs/ceph/mds_client.c
index d64413a..9967824 100644 (file)
--- a/fs/ceph/mds_client.c
+++ b/fs/ceph/mds_client.c
@@ -1619,7 +1619,6 @@ static int remove_session_caps_cb(struct inode *inode, struct ceph_cap *cap,
        struct ceph_fs_client *fsc = (struct ceph_fs_client *)arg;
        struct ceph_mds_client *mdsc = fsc->mdsc;
        struct ceph_inode_info *ci = ceph_inode(inode);
-       LIST_HEAD(to_remove);
        bool dirty_dropped = false;
        bool invalidate = false;
        int capsnap_release = 0;
@@ -1638,16 +1637,17 @@ static int remove_session_caps_cb(struct inode *inode, struct ceph_cap *cap,
                                mapping_set_error(&inode->i_data, -EIO);
                }
 
+               spin_lock(&mdsc->cap_dirty_lock);
+
+               /* trash all of the cap flushes for this inode */
                while (!list_empty(&ci->i_cap_flush_list)) {
                        cf = list_first_entry(&ci->i_cap_flush_list,
                                              struct ceph_cap_flush, i_list);
-                       list_move(&cf->i_list, &to_remove);
-               }
-
-               spin_lock(&mdsc->cap_dirty_lock);
-
-               list_for_each_entry(cf, &to_remove, i_list)
                        list_del_init(&cf->g_list);
+                       list_del_init(&cf->i_list);
+                       if (!cf->is_capsnap)
+                               ceph_free_cap_flush(cf);
+               }
 
                if (!list_empty(&ci->i_dirty_item)) {
                        pr_warn_ratelimited(
@@ -1690,22 +1690,16 @@ static int remove_session_caps_cb(struct inode *inode, struct ceph_cap *cap,
                }
 
                if (!ci->i_dirty_caps && ci->i_prealloc_cap_flush) {
-                       list_add(&ci->i_prealloc_cap_flush->i_list, &to_remove);
+                       cf = ci->i_prealloc_cap_flush;
                        ci->i_prealloc_cap_flush = NULL;
+                       if (!cf->is_capsnap)
+                               ceph_free_cap_flush(cf);
                }
 
                if (!list_empty(&ci->i_cap_snaps))
                        capsnap_release = remove_capsnaps(mdsc, inode);
        }
        spin_unlock(&ci->i_ceph_lock);
-       while (!list_empty(&to_remove)) {
-               struct ceph_cap_flush *cf;
-               cf = list_first_entry(&to_remove,
-                                     struct ceph_cap_flush, i_list);
-               list_del_init(&cf->i_list);
-               if (!cf->is_capsnap)
-                       ceph_free_cap_flush(cf);
-       }
 
        wake_up_all(&ci->i_cap_wq);
        if (invalidate)