xfs: refactor redo intent item processing

Refactor the EFI intent item recovery (and cancellation) functions
into a general function that scans the AIL and an intent item type
specific handler.  Move the function that recovers a single EFI item
into the extent free item code.  We'll want the generalized function
when we start wiring up more redo item types.

Furthermore, ensure that log recovery only replays the redo items
that were in the AIL prior to recovery by checking the item LSN
against the largest LSN seen during log scanning.  As written this
should never happen, but we can be defensive anyway.

Signed-off-by: Darrick J. Wong <darrick.wong@oracle.com>
Reviewed-by: Brian Foster <bfoster@redhat.com>
Signed-off-by: Dave Chinner <david@fromorbit.com>

fs/xfs/xfs_extfree_item.h

@@ -98,4 +98,7 @@ int			xfs_efi_copy_format(xfs_log_iovec_t *buf,
 void			xfs_efi_item_free(xfs_efi_log_item_t *);
 void			xfs_efi_release(struct xfs_efi_log_item *);
 
+int			xfs_efi_recover(struct xfs_mount *mp,
+					struct xfs_efi_log_item *efip);
+
 #endif	/* __XFS_EXTFREE_ITEM_H__ */