3 files changed, 117 insertions, 8 deletions

diff --git a/fs/xfs/libxfs/xfs_alloc.c b/fs/xfs/libxfs/xfs_alloc.c
index c35224ad9428..4940f9377f21 100644
--- a/fs/xfs/libxfs/xfs_alloc.c
+++ b/fs/xfs/libxfs/xfs_alloc.c
@@ -2522,14 +2522,15 @@ xfs_defer_agfl_block(
  * Add the extent to the list of extents to be free at transaction end.
  * The list is maintained sorted (by block number).
  */
-int
-xfs_free_extent_later(
+static int
+xfs_defer_extent_free(
 	struct xfs_trans		*tp,
 	xfs_fsblock_t			bno,
 	xfs_filblks_t			len,
 	const struct xfs_owner_info	*oinfo,
 	enum xfs_ag_resv_type		type,
-	bool				skip_discard)
+	bool				skip_discard,
+	struct xfs_defer_pending	**dfpp)
 {
 	struct xfs_extent_free_item	*xefi;
 	struct xfs_mount		*mp = tp->t_mountp;
@@ -2577,10 +2578,105 @@ xfs_free_extent_later(
 			XFS_FSB_TO_AGBNO(tp->t_mountp, bno), len);
 
 	xfs_extent_free_get_group(mp, xefi);
-	xfs_defer_add(tp, XFS_DEFER_OPS_TYPE_FREE, &xefi->xefi_list);
+	*dfpp = xfs_defer_add(tp, XFS_DEFER_OPS_TYPE_FREE, &xefi->xefi_list);
+	return 0;
+}
+
+int
+xfs_free_extent_later(
+	struct xfs_trans		*tp,
+	xfs_fsblock_t			bno,
+	xfs_filblks_t			len,
+	const struct xfs_owner_info	*oinfo,
+	enum xfs_ag_resv_type		type,
+	bool				skip_discard)
+{
+	struct xfs_defer_pending	*dontcare = NULL;
+
+	return xfs_defer_extent_free(tp, bno, len, oinfo, type, skip_discard,
+			&dontcare);
+}
+
+/*
+ * Set up automatic freeing of unwritten space in the filesystem.
+ *
+ * This function attached a paused deferred extent free item to the
+ * transaction.  Pausing means that the EFI will be logged in the next
+ * transaction commit, but the pending EFI will not be finished until the
+ * pending item is unpaused.
+ *
+ * If the system goes down after the EFI has been persisted to the log but
+ * before the pending item is unpaused, log recovery will find the EFI, fail to
+ * find the EFD, and free the space.
+ *
+ * If the pending item is unpaused, the next transaction commit will log an EFD
+ * without freeing the space.
+ *
+ * Caller must ensure that the tp, fsbno, len, oinfo, and resv flags of the
+ * @args structure are set to the relevant values.
+ */
+int
+xfs_alloc_schedule_autoreap(
+	const struct xfs_alloc_arg	*args,
+	bool				skip_discard,
+	struct xfs_alloc_autoreap	*aarp)
+{
+	int				error;
+
+	error = xfs_defer_extent_free(args->tp, args->fsbno, args->len,
+			&args->oinfo, args->resv, skip_discard, &aarp->dfp);
+	if (error)
+		return error;
+
+	xfs_defer_item_pause(args->tp, aarp->dfp);
 	return 0;
 }
 
+/*
+ * Cancel automatic freeing of unwritten space in the filesystem.
+ *
+ * Earlier, we created a paused deferred extent free item and attached it to
+ * this transaction so that we could automatically roll back a new space
+ * allocation if the system went down.  Now we want to cancel the paused work
+ * item by marking the EFI stale so we don't actually free the space, unpausing
+ * the pending item and logging an EFD.
+ *
+ * The caller generally should have already mapped the space into the ondisk
+ * filesystem.  If the reserved space was partially used, the caller must call
+ * xfs_free_extent_later to create a new EFI to free the unused space.
+ */
+void
+xfs_alloc_cancel_autoreap(
+	struct xfs_trans		*tp,
+	struct xfs_alloc_autoreap	*aarp)
+{
+	struct xfs_defer_pending	*dfp = aarp->dfp;
+	struct xfs_extent_free_item	*xefi;
+
+	if (!dfp)
+		return;
+
+	list_for_each_entry(xefi, &dfp->dfp_work, xefi_list)
+		xefi->xefi_flags |= XFS_EFI_CANCELLED;
+
+	xfs_defer_item_unpause(tp, dfp);
+}
+
+/*
+ * Commit automatic freeing of unwritten space in the filesystem.
+ *
+ * This unpauses an earlier _schedule_autoreap and commits to freeing the
+ * allocated space.  Call this if none of the reserved space was used.
+ */
+void
+xfs_alloc_commit_autoreap(
+	struct xfs_trans		*tp,
+	struct xfs_alloc_autoreap	*aarp)
+{
+	if (aarp->dfp)
+		xfs_defer_item_unpause(tp, aarp->dfp);
+}
+
 #ifdef DEBUG
 /*
  * Check if an AGF has a free extent record whose length is equal to
diff --git a/fs/xfs/libxfs/xfs_alloc.h b/fs/xfs/libxfs/xfs_alloc.h
index 6b95d1d8a853..851cafbd6449 100644
--- a/fs/xfs/libxfs/xfs_alloc.h
+++ b/fs/xfs/libxfs/xfs_alloc.h
@@ -255,6 +255,18 @@ void xfs_extent_free_get_group(struct xfs_mount *mp,
 #define XFS_EFI_SKIP_DISCARD	(1U << 0) /* don't issue discard */
 #define XFS_EFI_ATTR_FORK	(1U << 1) /* freeing attr fork block */
 #define XFS_EFI_BMBT_BLOCK	(1U << 2) /* freeing bmap btree block */
+#define XFS_EFI_CANCELLED	(1U << 3) /* dont actually free the space */
+
+struct xfs_alloc_autoreap {
+	struct xfs_defer_pending	*dfp;
+};
+
+int xfs_alloc_schedule_autoreap(const struct xfs_alloc_arg *args,
+		bool skip_discard, struct xfs_alloc_autoreap *aarp);
+void xfs_alloc_cancel_autoreap(struct xfs_trans *tp,
+		struct xfs_alloc_autoreap *aarp);
+void xfs_alloc_commit_autoreap(struct xfs_trans *tp,
+		struct xfs_alloc_autoreap *aarp);
 
 extern struct kmem_cache	*xfs_extfree_item_cache;
 
diff --git a/fs/xfs/xfs_extfree_item.c b/fs/xfs/xfs_extfree_item.c
index 3ca23ab8d92a..3e3469504271 100644
--- a/fs/xfs/xfs_extfree_item.c
+++ b/fs/xfs/xfs_extfree_item.c
@@ -453,7 +453,7 @@ xfs_extent_free_finish_item(
 	struct xfs_extent		*extp;
 	uint				next_extent;
 	xfs_agblock_t			agbno;
-	int				error;
+	int				error = 0;
 
 	xefi = container_of(item, struct xfs_extent_free_item, xefi_list);
 	agbno = XFS_FSB_TO_AGBNO(mp, xefi->xefi_startblock);
@@ -473,9 +473,10 @@ xfs_extent_free_finish_item(
 	 * the existing EFI, and so we need to copy all the unprocessed extents
 	 * in this EFI to the EFD so this works correctly.
 	 */
-	error = __xfs_free_extent(tp, xefi->xefi_pag, agbno,
-			xefi->xefi_blockcount, &oinfo, xefi->xefi_agresv,
-			xefi->xefi_flags & XFS_EFI_SKIP_DISCARD);
+	if (!(xefi->xefi_flags & XFS_EFI_CANCELLED))
+		error = __xfs_free_extent(tp, xefi->xefi_pag, agbno,
+				xefi->xefi_blockcount, &oinfo, xefi->xefi_agresv,
+				xefi->xefi_flags & XFS_EFI_SKIP_DISCARD);
 	if (error == -EAGAIN) {
 		xfs_efd_from_efi(efdp);
 		return error;