xfs: get rid of xfs_ag_resv_rmapbt_alloc

The pag in xfs_ag_resv_rmapbt_alloc() is already held when the struct
xfs_btree_cur is initialized in xfs_rmapbt_init_cursor(), so there is no
need to get pag again.

On the other hand, in xfs_rmapbt_free_block(), the similar function
xfs_ag_resv_rmapbt_free() was removed in commit 92a0054 ("xfs: get
rid of unnecessary xfs_perag_{get,put} pairs"), xfs_ag_resv_rmapbt_alloc()
was left because scrub used it, but now scrub has removed it. Therefore,
we could get rid of xfs_ag_resv_rmapbt_alloc() just like the rmap free
block, make the code cleaner.

Signed-off-by: Long Li <leo.lilong@huawei.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Darrick J. Wong <djwong@kernel.org>
Signed-off-by: Chandan Babu R <chandanbabu@kernel.org>

Author: Long Li

fs/xfs/libxfs/xfs_ag_resv.h

@@ -33,23 +33,4 @@ xfs_perag_resv(
 	}
 }
 
-/*
- * RMAPBT reservation accounting wrappers. Since rmapbt blocks are sourced from
- * the AGFL, they are allocated one at a time and the reservation updates don't
- * require a transaction.
- */
-static inline void
-xfs_ag_resv_rmapbt_alloc(
-	struct xfs_mount	*mp,
-	xfs_agnumber_t		agno)
-{
-	struct xfs_alloc_arg	args = { NULL };
-	struct xfs_perag	*pag;
-
-	args.len = 1;
-	pag = xfs_perag_get(mp, agno);
-	xfs_ag_resv_alloc_extent(pag, XFS_AG_RESV_RMAPBT, &args);
-	xfs_perag_put(pag);
-}
-
 #endif	/* __XFS_AG_RESV_H__ */

fs/xfs/libxfs/xfs_rmap_btree.c

@@ -88,6 +88,7 @@ xfs_rmapbt_alloc_block(
 	struct xfs_buf		*agbp = cur->bc_ag.agbp;
 	struct xfs_agf		*agf = agbp->b_addr;
 	struct xfs_perag	*pag = cur->bc_ag.pag;
+	struct xfs_alloc_arg    args = { .len = 1 };
 	int			error;
 	xfs_agblock_t		bno;
 
@@ -107,7 +108,11 @@ xfs_rmapbt_alloc_block(
 	be32_add_cpu(&agf->agf_rmap_blocks, 1);
 	xfs_alloc_log_agf(cur->bc_tp, agbp, XFS_AGF_RMAP_BLOCKS);
 
-	xfs_ag_resv_rmapbt_alloc(cur->bc_mp, pag->pag_agno);
+	/*
+	 * Since rmapbt blocks are sourced from the AGFL, they are allocated one
+	 * at a time and the reservation updates don't require a transaction.
+	 */
+	xfs_ag_resv_alloc_extent(pag, XFS_AG_RESV_RMAPBT, &args);
 
 	*stat = 1;
 	return 0;