HAMMER - Add additional warnings for v2/v3 upgrades, fix bug in snaprm

* Add warnings related to backup scripts when upgrading from V2 to V3.
  The synctid directive does not generate a snapshot.  You should generate
  a real snapshot to properly track them.

  Also, removing a snapshot softlink does not remove the meta-data and
  thus the pruning code will continue to prune around that snapshot.
  The snaprm directive should be used when removing snapshot softlinks
  to also remove the meta-data.

* Snaprm now uses the current directory when removing a transaction id
  and no target directory was specified.

* Snaprm now makes it clear that a failure to remove meta-data when
  removing a softlink is just a warning, not a fatal error.

diff --git a/sbin/hammer/cmd_snapshot.c b/sbin/hammer/cmd_snapshot.c
index cfc113b..1ae270a 100644 (file)
--- a/sbin/hammer/cmd_snapshot.c
+++ b/sbin/hammer/cmd_snapshot.c
@@ -210,6 +210,8 @@ hammer_cmd_snaprm(char **av, int ac)
                                    av[i]);
                                /* not reached */
                        }
+                       if (fsfd < 0)
+                               fsfd = open(".", O_RDONLY);
                        snapshot_del(fsfd, tid);
                } else if (S_ISDIR(st.st_mode)) {
                        if (fsfd >= 0)
@@ -503,10 +505,18 @@ snapshot_del(int fsfd, hammer_tid_t tid)
        snapshot.count = 1;
        snapshot.snaps[0].tid = tid;
 
+       /*
+        * Do not abort if we are unable to remove the meta-data.
+        */
        if (ioctl(fsfd, HAMMERIOC_DEL_SNAPSHOT, &snapshot) < 0) {
-               err(2, "hammer snaprm 0x%016jx", (uintmax_t)tid);
+               err(2, "hammer snaprm 0x%016jx",
+                     (uintmax_t)tid);
+       } else if (snapshot.head.error == ENOENT) {
+               fprintf(stderr, "Warning: hammer snaprm 0x%016jx: "
+                               "meta-data not found\n",
+                       (uintmax_t)tid);
        } else if (snapshot.head.error) {
-               fprintf(stderr, "hammer snaprm 0x%016jx: %s\n",
+               fprintf(stderr, "Warning: hammer snaprm 0x%016jx: %s\n",
                        (uintmax_t)tid, strerror(snapshot.head.error));
        }
 }

diff --git a/sbin/hammer/hammer.8 b/sbin/hammer/hammer.8
index 77deaa0..13ed973 100644 (file)
--- a/sbin/hammer/hammer.8
+++ b/sbin/hammer/hammer.8
@@ -1099,6 +1099,30 @@ the
 .Cm snapls
 directive to get a definitive list from the meta-data and
 regenerate them from that list.
+.Pp
+WARNING!  If you are using hammer to backup filesystems your scripts
+may be using the
+.Cm synctid
+directive to generate transaction ids.  This directive does not create
+a snapshot.  You will have to modify your scripts to use the
+.Cm snapq
+directive to generate the linkbuf for the softlink you create, or
+use one of the other
+.Cm snap*
+directives.
+The older
+.Cm snapshot
+directive will continue to work as expected and in V3 it will also
+record the snapshot transaction id in meta-data.  You may also want
+to make use of the new 'note' tag for the meta-data.
+.Pp
+WARNING!  If you used to remove snapshot softlinks with
+.Nm rm
+you should probably start using the
+.Cm snaprm
+directive instead to also remove the related meta-data.
+The pruning code scans the meta-data so just removing the
+softlink is not sufficient.
 .Sh FILES
 .Bl -tag -width ".It Pa <fs>/var/slaves/<name>" -compact
 .It Pa <pfs>/snapshots