xfs: always honor OWN_UNKNOWN rmap removal requests

Calling xfs_rmap_free with an unknown owner is supposed to remove any
rmaps covering that range regardless of owner. This is used by the EFI
recovery code to say "we're freeing this, it mustn't be owned by
anything anymore", but for whatever reason xfs_free_ag_extent filters
them out.

Therefore, remove the filter and make xfs_rmap_unmap actually treat it
as a wildcard owner -- free anything that's already there, and if
there's no owner at all then that's fine too.

There are two existing callers of bmap_add_free that take care the rmap
deferred ops themselves and use OWN_UNKNOWN to skip the EFI-based rmap
cleanup; convert these to use OWN_NULL (via helpers), and now we really
require that an RUI (if any) gets added to the defer ops before any EFI.

Lastly, now that xfs_free_extent filters out OWN_NULL rmap free requests,
growfs will have to consult directly with the rmap to ensure that there
aren't any rmaps in the grown region.

Signed-off-by: Darrick J. Wong <[e-mail]>
Reviewed-by: Christoph Hellwig <[e-mail]>

fs/xfs/libxfs/xfs_alloc.c

···
 	ASSERT(args->agbno % args->alignment == 0);
 
 	/* if not file data, insert new block into the reverse map btree */
-	if (args->oinfo.oi_owner != XFS_RMAP_OWN_UNKNOWN) {
+	if (!xfs_rmap_should_skip_owner_update(&args->oinfo)) {
 		error = xfs_rmap_alloc(args->tp, args->agbp, args->agno,
 				       args->agbno, args->len, &args->oinfo);
 		if (error)
···
 	bno_cur = cnt_cur = NULL;
 	mp = tp->t_mountp;
 
-	if (oinfo->oi_owner != XFS_RMAP_OWN_UNKNOWN) {
+	if (!xfs_rmap_should_skip_owner_update(oinfo)) {
 		error = xfs_rmap_free(tp, agbp, agno, bno, len, oinfo);
 		if (error)
 			goto error0;

fs/xfs/libxfs/xfs_rmap.c

···
 		goto out_done;
 	}
 
+	/*
+	 * If we're doing an unknown-owner removal for EFI recovery, we expect
+	 * to find the full range in the rmapbt or nothing at all.  If we
+	 * don't find any rmaps overlapping either end of the range, we're
+	 * done.  Hopefully this means that the EFI creator already queued
+	 * (and finished) a RUI to remove the rmap.
+	 */
+	if (owner == XFS_RMAP_OWN_UNKNOWN &&
+	    ltrec.rm_startblock + ltrec.rm_blockcount <= bno) {
+		struct xfs_rmap_irec    rtrec;
+
+		error = xfs_btree_increment(cur, 0, &i);
+		if (error)
+			goto out_error;
+		if (i == 0)
+			goto out_done;
+		error = xfs_rmap_get_rec(cur, &rtrec, &i);
+		if (error)
+			goto out_error;
+		XFS_WANT_CORRUPTED_GOTO(mp, i == 1, out_error);
+		if (rtrec.rm_startblock >= bno + len)
+			goto out_done;
+	}
+
 	/* Make sure the unwritten flag matches. */
 	XFS_WANT_CORRUPTED_GOTO(mp, (flags & XFS_RMAP_UNWRITTEN) ==
 			(ltrec.rm_flags & XFS_RMAP_UNWRITTEN), out_error);
···
 		flags |= XFS_RMAP_UNWRITTEN;
 	trace_xfs_rmap_map(mp, cur->bc_private.a.agno, bno, len,
 			unwritten, oinfo);
+	ASSERT(!xfs_rmap_should_skip_owner_update(oinfo));
 
 	/*
 	 * For the initial lookup, look for an exact match or the left-adjacent

fs/xfs/libxfs/xfs_rmap.h

···
 xfs_rmap_skip_owner_update(
 	struct xfs_owner_info	*oi)
 {
-	oi->oi_owner = XFS_RMAP_OWN_UNKNOWN;
+	xfs_rmap_ag_owner(oi, XFS_RMAP_OWN_NULL);
+}
+
+static inline bool
+xfs_rmap_should_skip_owner_update(
+	struct xfs_owner_info	*oi)
+{
+	return oi->oi_owner == XFS_RMAP_OWN_NULL;
+}
+
+static inline void
+xfs_rmap_any_owner_update(
+	struct xfs_owner_info	*oi)
+{
+	xfs_rmap_ag_owner(oi, XFS_RMAP_OWN_UNKNOWN);
 }
 
 /* Reverse mapping functions. */

fs/xfs/xfs_extfree_item.c

···
 		return error;
 	efdp = xfs_trans_get_efd(tp, efip, efip->efi_format.efi_nextents);
 
-	xfs_rmap_skip_owner_update(&oinfo);
+	xfs_rmap_any_owner_update(&oinfo);
 	for (i = 0; i < efip->efi_format.efi_nextents; i++) {
 		extp = &efip->efi_format.efi_extents[i];
 		error = xfs_trans_free_extent(tp, efdp, extp->ext_start,

fs/xfs/xfs_fsops.c

···
 		 * this doesn't actually exist in the rmap btree.
 		 */
 		xfs_rmap_ag_owner(&oinfo, XFS_RMAP_OWN_NULL);
+		error = xfs_rmap_free(tp, bp, agno,
+				be32_to_cpu(agf->agf_length) - new,
+				new, &oinfo);
+		if (error)
+			goto error0;
 		error = xfs_free_extent(tp,
 				XFS_AGB_TO_FSB(mp, agno,
 					be32_to_cpu(agf->agf_length) - new),