gfs2: Only use struct gfs2_rbm for bitmap manipulations

GFS2 uses struct gfs2_rbm to represent a filesystem block number as a
bit position within a resource group.  This representation is used in
the bitmap manipulation code to prevent excessive conversions between
block numbers and bit positions, but also in struct gfs2_blkreserv which
is part of struct gfs2_inode, to mark the start of a reservation.  In
the inode, the bit position representation makes less sense: first, the
start position is used as a block number about as often as a bit
position; second, the bit position representation makes the code
unnecessarily complicated and difficult to read.

Therefore, change struct gfs2_blkreserv to represent the start of a
reservation as a block number instead of a bit position.  (This requires
keeping track of the resource group in gfs2_blkreserv separately.) With
that change, various things can be slightly simplified, and struct
gfs2_rbm can be moved to rgrp.c.

Signed-off-by: Andreas Gruenbacher <agruenba@redhat.com>

fs/gfs2/bmap.c

@@ -1544,7 +1544,7 @@ static int sweep_bh_for_rgrps(struct gfs2_inode *ip, struct gfs2_holder *rd_gh,
 
 			/* Must be done with the rgrp glock held: */
 			if (gfs2_rs_active(&ip->i_res) &&
-			    rgd == ip->i_res.rs_rbm.rgd)
+			    rgd == ip->i_res.rs_rgd)
 				gfs2_rs_deltree(&ip->i_res);
 		}
 

fs/gfs2/incore.h

@@ -125,31 +125,6 @@ struct gfs2_rgrpd {
 	struct rb_root rd_rstree;       /* multi-block reservation tree */
 };
 
-struct gfs2_rbm {
-	struct gfs2_rgrpd *rgd;
-	u32 offset;		/* The offset is bitmap relative */
-	int bii;		/* Bitmap index */
-};
-
-static inline struct gfs2_bitmap *rbm_bi(const struct gfs2_rbm *rbm)
-{
-	return rbm->rgd->rd_bits + rbm->bii;
-}
-
-static inline u64 gfs2_rbm_to_block(const struct gfs2_rbm *rbm)
-{
-	BUG_ON(rbm->offset >= rbm->rgd->rd_data);
-	return rbm->rgd->rd_data0 + (rbm_bi(rbm)->bi_start * GFS2_NBBY) +
-		rbm->offset;
-}
-
-static inline bool gfs2_rbm_eq(const struct gfs2_rbm *rbm1,
-			       const struct gfs2_rbm *rbm2)
-{
-	return (rbm1->rgd == rbm2->rgd) && (rbm1->bii == rbm2->bii) &&
-	       (rbm1->offset == rbm2->offset);
-}
-
 enum gfs2_state_bits {
 	BH_Pinned = BH_PrivateStart,
 	BH_Escaped = BH_PrivateStart + 1,
@@ -313,8 +288,9 @@ struct gfs2_qadata { /* quota allocation data */
 */
 
 struct gfs2_blkreserv {
-	struct rb_node rs_node;       /* link to other block reservations */
-	struct gfs2_rbm rs_rbm;       /* Start of reservation */
+	struct rb_node rs_node;       /* node within rd_rstree */
+	struct gfs2_rgrpd *rs_rgd;
+	u64 rs_start;		      /* start of reservation */
 	u32 rs_free;                  /* how many blocks are still free */
 };