WAPBL not locking enough?

[coypu%SDF.ORG@localhost]

Hi,

I fear that WAPBL should be locking wl_mtx before running
wapbl_transaction_len (in wapbl_flush)

I suspect so because it performs a similar lock before
looking at wl_bufcount in sys/kern/vfs_wapbl.c:1455-1460.

If true, how about this diff?

diff --git a/sys/kern/vfs_wapbl.c b/sys/kern/vfs_wapbl.c
index 378b0ba..f765ce3 100644
--- a/sys/kern/vfs_wapbl.c
+++ b/sys/kern/vfs_wapbl.c
@@ -1971,6 +1971,7 @@ wapbl_transaction_len(struct wapbl *wl)
        size_t len;
        int bph;
 
+       mutex_enter(&wl->wl_mtx);
        /* Calculate number of blocks described in a blocklist header */
        bph = (blocklen - offsetof(struct wapbl_wc_blocklist, wc_blocks)) /
            sizeof(((struct wapbl_wc_blocklist *)0)->wc_blocks[0]);
@@ -1981,6 +1982,7 @@ wapbl_transaction_len(struct wapbl *wl)
        len += howmany(wl->wl_bufcount, bph) * blocklen;
        len += howmany(wl->wl_dealloccnt, bph) * blocklen;
        len += wapbl_transaction_inodes_len(wl);
+       mutex_exit(&wl->wl_mtx);
 
        return len;
 }