xfs: convert drop_writes to use the errortag mechanism

We now have enhanced error injection that can control the frequency
with which errors happen, so convert drop_writes to use this.

Signed-off-by: Darrick J. Wong <darrick.wong@oracle.com>
Reviewed-by: Brian Foster <bfoster@redhat.com>
Reviewed-by: Carlos Maiolino <cmaiolino@redhat.com>

fs/xfs/xfs_mount.h

@@ -205,16 +205,6 @@ typedef struct xfs_mount {
 	 */
 	unsigned int		*m_errortag;
 	struct xfs_kobj		m_errortag_kobj;
-
-	/*
-	 * DEBUG mode instrumentation to test and/or trigger delayed allocation
-	 * block killing in the event of failed writes. When enabled, all
-	 * buffered writes are silenty dropped and handled as if they failed.
-	 * All delalloc blocks in the range of the write (including pre-existing
-	 * delalloc blocks!) are tossed as part of the write failure error
-	 * handling sequence.
-	 */
-	bool			m_drop_writes;
 #endif
 } xfs_mount_t;
 
@@ -333,20 +323,6 @@ xfs_daddr_to_agbno(struct xfs_mount *mp, xfs_daddr_t d)
 	return (xfs_agblock_t) do_div(ld, mp->m_sb.sb_agblocks);
 }
 
-#ifdef DEBUG
-static inline bool
-xfs_mp_drop_writes(struct xfs_mount *mp)
-{
-	return mp->m_drop_writes;
-}
-#else
-static inline bool
-xfs_mp_drop_writes(struct xfs_mount *mp)
-{
-	return 0;
-}
-#endif
-
 /* per-AG block reservation data structures*/
 enum xfs_ag_resv_type {
 	XFS_AG_RESV_NONE = 0,