xfs: remove unnecessary null pointer checks from _read_agf callers

Drop the null buffer pointer checks in all code that calls
xfs_alloc_read_agf and doesn't pass XFS_ALLOC_FLAG_TRYLOCK because
they're no longer necessary.
Signed-off-by: Darrick J. Wong <darrick.wong@oracle.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Dave Chinner <dchinner@redhat.com>

fs/xfs/libxfs/xfs_refcount.c

@@ -1177,8 +1177,6 @@ xfs_refcount_finish_one(
 				XFS_ALLOC_FLAG_FREEING, &agbp);
 		if (error)
 			return error;
-		if (XFS_IS_CORRUPT(tp->t_mountp, !agbp))
-			return -EFSCORRUPTED;
 
 		rcur = xfs_refcountbt_init_cursor(mp, tp, agbp, agno);
 		if (!rcur) {
@@ -1718,10 +1716,6 @@ xfs_refcount_recover_cow_leftovers(
 	error = xfs_alloc_read_agf(mp, tp, agno, 0, &agbp);
 	if (error)
 		goto out_trans;
-	if (!agbp) {
-		error = -ENOMEM;
-		goto out_trans;
-	}
 	cur = xfs_refcountbt_init_cursor(mp, tp, agbp, agno);
 
 	/* Find all the leftover CoW staging extents. */

fs/xfs/scrub/agheader_repair.c

@@ -659,8 +659,6 @@ xrep_agfl(
 	error = xfs_alloc_read_agf(mp, sc->tp, sc->sa.agno, 0, &agf_bp);
 	if (error)
 		return error;
-	if (!agf_bp)
-		return -ENOMEM;
 
 	/*
 	 * Make sure we have the AGFL buffer, as scrub might have decided it
@@ -735,8 +733,6 @@ xrep_agi_find_btrees(
 	error = xfs_alloc_read_agf(mp, sc->tp, sc->sa.agno, 0, &agf_bp);
 	if (error)
 		return error;
-	if (!agf_bp)
-		return -ENOMEM;
 
 	/* Find the btree roots. */
 	error = xrep_find_ag_btree_roots(sc, agf_bp, fab, NULL);

fs/xfs/scrub/fscounters.c

@@ -83,9 +83,6 @@ xchk_fscount_warmup(
 		error = xfs_alloc_read_agf(mp, sc->tp, agno, 0, &agf_bp);
 		if (error)
 			break;
-		error = -ENOMEM;
-		if (!agf_bp || !agi_bp)
-			break;
 
 		/*
 		 * These are supposed to be initialized by the header read

fs/xfs/scrub/repair.c

@@ -546,8 +546,6 @@ xrep_reap_block(
 		error = xfs_alloc_read_agf(sc->mp, sc->tp, agno, 0, &agf_bp);
 		if (error)
 			return error;
-		if (!agf_bp)
-			return -ENOMEM;
 	} else {
 		agf_bp = sc->sa.agf_bp;
 	}

fs/xfs/xfs_discard.c

@@ -45,7 +45,7 @@ xfs_trim_extents(
 	xfs_log_force(mp, XFS_LOG_SYNC);
 
 	error = xfs_alloc_read_agf(mp, NULL, agno, 0, &agbp);
-	if (error || !agbp)
+	if (error)
 		goto out_put_perag;
 
 	cur = xfs_allocbt_init_cursor(mp, NULL, agbp, agno, XFS_BTNUM_CNT);

fs/xfs/xfs_reflink.c

@@ -143,8 +143,6 @@ xfs_reflink_find_shared(
 	error = xfs_alloc_read_agf(mp, tp, agno, 0, &agbp);
 	if (error)
 		return error;
-	if (!agbp)
-		return -ENOMEM;
 
 	cur = xfs_refcountbt_init_cursor(mp, tp, agbp, agno);