zfs: Add a comment to clarify nvlist memory layout

Signed-off-by: Phaedrus Leeds <mwleeds@mailtundra.com>

diff --git a/fs/zfs/zfs.c b/fs/zfs/zfs.c
index 14779dee32d834de2d026b563f52a75448173a4c..61d58fce68dc6c8e4204f18e8f8a22a1825b5990 100644 (file)
--- a/fs/zfs/zfs.c
+++ b/fs/zfs/zfs.c
@@ -1617,6 +1617,11 @@ zfs_nvlist_lookup_nvlist(char *nvlist, char *name)
                                                          &size, 0);
        if (!found)
                return 0;
+
+       /* Allocate 12 bytes in addition to the nvlist size: One uint32 before the
+        * nvlist to hold the encoding method, and two zero uint32's after the
+        * nvlist as the NULL terminator.
+        */
        ret = calloc(1, size + 3 * sizeof(uint32_t));
        if (!ret)
                return 0;