From fa5a387230861116c2434c20d29fc4b3fd077d24 Mon Sep 17 00:00:00 2001
From: "Darrick J. Wong" <djwong@kernel.org>
Date: Mon, 16 Oct 2023 09:32:54 -0700
Subject: [PATCH 1/7] xfs: create a helper to convert rtextents to rtblocks

Create a helper to convert a realtime extent to a realtime block.  Later
on we'll change the helper to use bit shifts when possible.

Signed-off-by: Darrick J. Wong <djwong@kernel.org>
Reviewed-by: Christoph Hellwig <hch@lst.de>
---
 fs/xfs/libxfs/xfs_rtbitmap.h | 16 ++++++++++++++++
 fs/xfs/scrub/rtbitmap.c      |  4 ++--
 fs/xfs/scrub/rtsummary.c     |  4 ++--
 fs/xfs/xfs_bmap_util.c       |  9 +++++----
 fs/xfs/xfs_fsmap.c           |  6 +++---
 fs/xfs/xfs_super.c           |  3 ++-
 6 files changed, 30 insertions(+), 12 deletions(-)

diff --git a/fs/xfs/libxfs/xfs_rtbitmap.h b/fs/xfs/libxfs/xfs_rtbitmap.h
index 5e2afb7fea0e..099ea8902aaa 100644
--- a/fs/xfs/libxfs/xfs_rtbitmap.h
+++ b/fs/xfs/libxfs/xfs_rtbitmap.h
@@ -6,6 +6,22 @@
 #ifndef __XFS_RTBITMAP_H__
 #define	__XFS_RTBITMAP_H__
 
+static inline xfs_rtblock_t
+xfs_rtx_to_rtb(
+	struct xfs_mount	*mp,
+	xfs_rtxnum_t		rtx)
+{
+	return rtx * mp->m_sb.sb_rextsize;
+}
+
+static inline xfs_extlen_t
+xfs_rtxlen_to_extlen(
+	struct xfs_mount	*mp,
+	xfs_rtxlen_t		rtxlen)
+{
+	return rtxlen * mp->m_sb.sb_rextsize;
+}
+
 /*
  * Functions for walking free space rtextents in the realtime bitmap.
  */
diff --git a/fs/xfs/scrub/rtbitmap.c b/fs/xfs/scrub/rtbitmap.c
index bea5a2b75a06..584a2b8badac 100644
--- a/fs/xfs/scrub/rtbitmap.c
+++ b/fs/xfs/scrub/rtbitmap.c
@@ -50,8 +50,8 @@ xchk_rtbitmap_rec(
 	xfs_rtblock_t		startblock;
 	xfs_filblks_t		blockcount;
 
-	startblock = rec->ar_startext * mp->m_sb.sb_rextsize;
-	blockcount = rec->ar_extcount * mp->m_sb.sb_rextsize;
+	startblock = xfs_rtx_to_rtb(mp, rec->ar_startext);
+	blockcount = xfs_rtx_to_rtb(mp, rec->ar_extcount);
 
 	if (!xfs_verify_rtbext(mp, startblock, blockcount))
 		xchk_fblock_set_corrupt(sc, XFS_DATA_FORK, 0);
diff --git a/fs/xfs/scrub/rtsummary.c b/fs/xfs/scrub/rtsummary.c
index d998f0c378a4..d363286e8b72 100644
--- a/fs/xfs/scrub/rtsummary.c
+++ b/fs/xfs/scrub/rtsummary.c
@@ -134,8 +134,8 @@ xchk_rtsum_record_free(
 	lenlog = XFS_RTBLOCKLOG(rec->ar_extcount);
 	offs = XFS_SUMOFFS(mp, lenlog, rbmoff);
 
-	rtbno = rec->ar_startext * mp->m_sb.sb_rextsize;
-	rtlen = rec->ar_extcount * mp->m_sb.sb_rextsize;
+	rtbno = xfs_rtx_to_rtb(mp, rec->ar_startext);
+	rtlen = xfs_rtx_to_rtb(mp, rec->ar_extcount);
 
 	if (!xfs_verify_rtbext(mp, rtbno, rtlen)) {
 		xchk_ino_xref_set_corrupt(sc, mp->m_rbmip->i_ino);
diff --git a/fs/xfs/xfs_bmap_util.c b/fs/xfs/xfs_bmap_util.c
index 557330281ae3..2d747084c199 100644
--- a/fs/xfs/xfs_bmap_util.c
+++ b/fs/xfs/xfs_bmap_util.c
@@ -28,6 +28,7 @@
 #include "xfs_icache.h"
 #include "xfs_iomap.h"
 #include "xfs_reflink.h"
+#include "xfs_rtbitmap.h"
 
 /* Kernel only BMAP related definitions and functions */
 
@@ -125,7 +126,7 @@ xfs_bmap_rtalloc(
 	 * XFS_BMBT_MAX_EXTLEN), we don't hear about that number, and can't
 	 * adjust the starting point to match it.
 	 */
-	if (ralen * mp->m_sb.sb_rextsize >= XFS_MAX_BMBT_EXTLEN)
+	if (xfs_rtxlen_to_extlen(mp, ralen) >= XFS_MAX_BMBT_EXTLEN)
 		ralen = XFS_MAX_BMBT_EXTLEN / mp->m_sb.sb_rextsize;
 
 	/*
@@ -147,7 +148,7 @@ xfs_bmap_rtalloc(
 		error = xfs_rtpick_extent(mp, ap->tp, ralen, &rtx);
 		if (error)
 			return error;
-		ap->blkno = rtx * mp->m_sb.sb_rextsize;
+		ap->blkno = xfs_rtx_to_rtb(mp, rtx);
 	} else {
 		ap->blkno = 0;
 	}
@@ -170,8 +171,8 @@ xfs_bmap_rtalloc(
 		return error;
 
 	if (rtx != NULLRTEXTNO) {
-		ap->blkno = rtx * mp->m_sb.sb_rextsize;
-		ap->length = ralen * mp->m_sb.sb_rextsize;
+		ap->blkno = xfs_rtx_to_rtb(mp, rtx);
+		ap->length = xfs_rtxlen_to_extlen(mp, ralen);
 		ap->ip->i_nblocks += ap->length;
 		xfs_trans_log_inode(ap->tp, ap->ip, XFS_ILOG_CORE);
 		if (ap->wasdel)
diff --git a/fs/xfs/xfs_fsmap.c b/fs/xfs/xfs_fsmap.c
index 8982c5d6cbd0..1a187bc9da3d 100644
--- a/fs/xfs/xfs_fsmap.c
+++ b/fs/xfs/xfs_fsmap.c
@@ -483,11 +483,11 @@ xfs_getfsmap_rtdev_rtbitmap_helper(
 	xfs_rtblock_t			rtbno;
 	xfs_daddr_t			rec_daddr, len_daddr;
 
-	rtbno = rec->ar_startext * mp->m_sb.sb_rextsize;
+	rtbno = xfs_rtx_to_rtb(mp, rec->ar_startext);
 	rec_daddr = XFS_FSB_TO_BB(mp, rtbno);
 	irec.rm_startblock = rtbno;
 
-	rtbno = rec->ar_extcount * mp->m_sb.sb_rextsize;
+	rtbno = xfs_rtx_to_rtb(mp, rec->ar_extcount);
 	len_daddr = XFS_FSB_TO_BB(mp, rtbno);
 	irec.rm_blockcount = rtbno;
 
@@ -514,7 +514,7 @@ xfs_getfsmap_rtdev_rtbitmap(
 	uint64_t			eofs;
 	int				error;
 
-	eofs = XFS_FSB_TO_BB(mp, mp->m_sb.sb_rextents * mp->m_sb.sb_rextsize);
+	eofs = XFS_FSB_TO_BB(mp, xfs_rtx_to_rtb(mp, mp->m_sb.sb_rextents));
 	if (keys[0].fmr_physical >= eofs)
 		return 0;
 	start_rtb = XFS_BB_TO_FSBT(mp,
diff --git a/fs/xfs/xfs_super.c b/fs/xfs/xfs_super.c
index 819a3568b28f..991a31089dc7 100644
--- a/fs/xfs/xfs_super.c
+++ b/fs/xfs/xfs_super.c
@@ -42,6 +42,7 @@
 #include "xfs_xattr.h"
 #include "xfs_iunlink_item.h"
 #include "xfs_dahash_test.h"
+#include "xfs_rtbitmap.h"
 #include "scrub/stats.h"
 
 #include <linux/magic.h>
@@ -890,7 +891,7 @@ xfs_fs_statfs(
 
 		statp->f_blocks = sbp->sb_rblocks;
 		freertx = percpu_counter_sum_positive(&mp->m_frextents);
-		statp->f_bavail = statp->f_bfree = freertx * sbp->sb_rextsize;
+		statp->f_bavail = statp->f_bfree = xfs_rtx_to_rtb(mp, freertx);
 	}
 
 	return 0;

From 68db60bf01c131c09bbe35adf43bd957a4c124bc Mon Sep 17 00:00:00 2001
From: "Darrick J. Wong" <djwong@kernel.org>
Date: Mon, 16 Oct 2023 09:34:39 -0700
Subject: [PATCH 2/7] xfs: create a helper to compute leftovers of realtime
 extents

Create a helper to compute the misalignment between a file extent
(xfs_extlen_t) and a realtime extent.

Signed-off-by: Darrick J. Wong <djwong@kernel.org>
Reviewed-by: Christoph Hellwig <hch@lst.de>
---
 fs/xfs/libxfs/xfs_bmap.c     | 4 ++--
 fs/xfs/libxfs/xfs_rtbitmap.h | 9 +++++++++
 fs/xfs/scrub/inode.c         | 3 ++-
 fs/xfs/xfs_bmap_util.c       | 2 +-
 fs/xfs/xfs_inode_item.c      | 3 ++-
 fs/xfs/xfs_ioctl.c           | 5 +++--
 6 files changed, 19 insertions(+), 7 deletions(-)

diff --git a/fs/xfs/libxfs/xfs_bmap.c b/fs/xfs/libxfs/xfs_bmap.c
index 4e7de4f2fd7a..19203699b992 100644
--- a/fs/xfs/libxfs/xfs_bmap.c
+++ b/fs/xfs/libxfs/xfs_bmap.c
@@ -2989,7 +2989,7 @@ xfs_bmap_extsize_align(
 	 * If realtime, and the result isn't a multiple of the realtime
 	 * extent size we need to remove blocks until it is.
 	 */
-	if (rt && (temp = (align_alen % mp->m_sb.sb_rextsize))) {
+	if (rt && (temp = xfs_extlen_to_rtxmod(mp, align_alen))) {
 		/*
 		 * We're not covering the original request, or
 		 * we won't be able to once we fix the length.
@@ -3016,7 +3016,7 @@ xfs_bmap_extsize_align(
 		else {
 			align_alen -= orig_off - align_off;
 			align_off = orig_off;
-			align_alen -= align_alen % mp->m_sb.sb_rextsize;
+			align_alen -= xfs_extlen_to_rtxmod(mp, align_alen);
 		}
 		/*
 		 * Result doesn't cover the request, fail it.
diff --git a/fs/xfs/libxfs/xfs_rtbitmap.h b/fs/xfs/libxfs/xfs_rtbitmap.h
index 099ea8902aaa..b6a4c46bddc0 100644
--- a/fs/xfs/libxfs/xfs_rtbitmap.h
+++ b/fs/xfs/libxfs/xfs_rtbitmap.h
@@ -22,6 +22,15 @@ xfs_rtxlen_to_extlen(
 	return rtxlen * mp->m_sb.sb_rextsize;
 }
 
+/* Compute the misalignment between an extent length and a realtime extent .*/
+static inline unsigned int
+xfs_extlen_to_rtxmod(
+	struct xfs_mount	*mp,
+	xfs_extlen_t		len)
+{
+	return len % mp->m_sb.sb_rextsize;
+}
+
 /*
  * Functions for walking free space rtextents in the realtime bitmap.
  */
diff --git a/fs/xfs/scrub/inode.c b/fs/xfs/scrub/inode.c
index 59d7912fb75f..889f556bc98f 100644
--- a/fs/xfs/scrub/inode.c
+++ b/fs/xfs/scrub/inode.c
@@ -20,6 +20,7 @@
 #include "xfs_reflink.h"
 #include "xfs_rmap.h"
 #include "xfs_bmap_util.h"
+#include "xfs_rtbitmap.h"
 #include "scrub/scrub.h"
 #include "scrub/common.h"
 #include "scrub/btree.h"
@@ -225,7 +226,7 @@ xchk_inode_extsize(
 	 */
 	if ((flags & XFS_DIFLAG_RTINHERIT) &&
 	    (flags & XFS_DIFLAG_EXTSZINHERIT) &&
-	    value % sc->mp->m_sb.sb_rextsize > 0)
+	    xfs_extlen_to_rtxmod(sc->mp, value) > 0)
 		xchk_ino_set_warning(sc, ino);
 }
 
diff --git a/fs/xfs/xfs_bmap_util.c b/fs/xfs/xfs_bmap_util.c
index 2d747084c199..8895184ff90a 100644
--- a/fs/xfs/xfs_bmap_util.c
+++ b/fs/xfs/xfs_bmap_util.c
@@ -97,7 +97,7 @@ xfs_bmap_rtalloc(
 	if (error)
 		return error;
 	ASSERT(ap->length);
-	ASSERT(ap->length % mp->m_sb.sb_rextsize == 0);
+	ASSERT(xfs_extlen_to_rtxmod(mp, ap->length) == 0);
 
 	/*
 	 * If we shifted the file offset downward to satisfy an extent size
diff --git a/fs/xfs/xfs_inode_item.c b/fs/xfs/xfs_inode_item.c
index 127b2410eb20..3183d0b03e0b 100644
--- a/fs/xfs/xfs_inode_item.c
+++ b/fs/xfs/xfs_inode_item.c
@@ -19,6 +19,7 @@
 #include "xfs_log.h"
 #include "xfs_log_priv.h"
 #include "xfs_error.h"
+#include "xfs_rtbitmap.h"
 
 #include <linux/iversion.h>
 
@@ -107,7 +108,7 @@ xfs_inode_item_precommit(
 	 */
 	if ((ip->i_diflags & XFS_DIFLAG_RTINHERIT) &&
 	    (ip->i_diflags & XFS_DIFLAG_EXTSZINHERIT) &&
-	    (ip->i_extsize % ip->i_mount->m_sb.sb_rextsize) > 0) {
+	    xfs_extlen_to_rtxmod(ip->i_mount, ip->i_extsize) > 0) {
 		ip->i_diflags &= ~(XFS_DIFLAG_EXTSIZE |
 				   XFS_DIFLAG_EXTSZINHERIT);
 		ip->i_extsize = 0;
diff --git a/fs/xfs/xfs_ioctl.c b/fs/xfs/xfs_ioctl.c
index 55bb01173cde..a82470e027f7 100644
--- a/fs/xfs/xfs_ioctl.c
+++ b/fs/xfs/xfs_ioctl.c
@@ -38,6 +38,7 @@
 #include "xfs_reflink.h"
 #include "xfs_ioctl.h"
 #include "xfs_xattr.h"
+#include "xfs_rtbitmap.h"
 
 #include <linux/mount.h>
 #include <linux/namei.h>
@@ -1004,7 +1005,7 @@ xfs_fill_fsxattr(
 		 * later.
 		 */
 		if ((ip->i_diflags & XFS_DIFLAG_RTINHERIT) &&
-		    ip->i_extsize % mp->m_sb.sb_rextsize > 0) {
+		    xfs_extlen_to_rtxmod(mp, ip->i_extsize) > 0) {
 			fa->fsx_xflags &= ~(FS_XFLAG_EXTSIZE |
 					    FS_XFLAG_EXTSZINHERIT);
 			fa->fsx_extsize = 0;
@@ -1130,7 +1131,7 @@ xfs_ioctl_setattr_xflags(
 	/* If realtime flag is set then must have realtime device */
 	if (fa->fsx_xflags & FS_XFLAG_REALTIME) {
 		if (mp->m_sb.sb_rblocks == 0 || mp->m_sb.sb_rextsize == 0 ||
-		    (ip->i_extsize % mp->m_sb.sb_rextsize))
+		    xfs_extlen_to_rtxmod(mp, ip->i_extsize))
 			return -EINVAL;
 	}
 

From 2c2b981b737a519907429f62148bbd9e40e01132 Mon Sep 17 00:00:00 2001
From: "Darrick J. Wong" <djwong@kernel.org>
Date: Mon, 16 Oct 2023 09:35:23 -0700
Subject: [PATCH 3/7] xfs: create a helper to convert extlen to rtextlen

Create a helper to compute the realtime extent (xfs_rtxlen_t) from an
extent length (xfs_extlen_t) value.

Signed-off-by: Darrick J. Wong <djwong@kernel.org>
Reviewed-by: Christoph Hellwig <hch@lst.de>
---
 fs/xfs/libxfs/xfs_rtbitmap.h   |  8 ++++++++
 fs/xfs/libxfs/xfs_trans_resv.c |  3 ++-
 fs/xfs/xfs_bmap_util.c         | 11 ++++-------
 fs/xfs/xfs_trans.c             |  3 ++-
 4 files changed, 16 insertions(+), 9 deletions(-)

diff --git a/fs/xfs/libxfs/xfs_rtbitmap.h b/fs/xfs/libxfs/xfs_rtbitmap.h
index b6a4c46bddc0..e2a36fc157c4 100644
--- a/fs/xfs/libxfs/xfs_rtbitmap.h
+++ b/fs/xfs/libxfs/xfs_rtbitmap.h
@@ -31,6 +31,14 @@ xfs_extlen_to_rtxmod(
 	return len % mp->m_sb.sb_rextsize;
 }
 
+static inline xfs_rtxlen_t
+xfs_extlen_to_rtxlen(
+	struct xfs_mount	*mp,
+	xfs_extlen_t		len)
+{
+	return len / mp->m_sb.sb_rextsize;
+}
+
 /*
  * Functions for walking free space rtextents in the realtime bitmap.
  */
diff --git a/fs/xfs/libxfs/xfs_trans_resv.c b/fs/xfs/libxfs/xfs_trans_resv.c
index 5b2f27cbdb80..4629f10d2f67 100644
--- a/fs/xfs/libxfs/xfs_trans_resv.c
+++ b/fs/xfs/libxfs/xfs_trans_resv.c
@@ -19,6 +19,7 @@
 #include "xfs_trans.h"
 #include "xfs_qm.h"
 #include "xfs_trans_space.h"
+#include "xfs_rtbitmap.h"
 
 #define _ALLOC	true
 #define _FREE	false
@@ -220,7 +221,7 @@ xfs_rtalloc_block_count(
 	unsigned int		blksz = XFS_FSB_TO_B(mp, 1);
 	unsigned int		rtbmp_bytes;
 
-	rtbmp_bytes = (XFS_MAX_BMBT_EXTLEN / mp->m_sb.sb_rextsize) / NBBY;
+	rtbmp_bytes = xfs_extlen_to_rtxlen(mp, XFS_MAX_BMBT_EXTLEN) / NBBY;
 	return (howmany(rtbmp_bytes, blksz) + 1) * num_ops;
 }
 
diff --git a/fs/xfs/xfs_bmap_util.c b/fs/xfs/xfs_bmap_util.c
index 8895184ff90a..4f53f784f06d 100644
--- a/fs/xfs/xfs_bmap_util.c
+++ b/fs/xfs/xfs_bmap_util.c
@@ -90,7 +90,7 @@ xfs_bmap_rtalloc(
 
 	align = xfs_get_extsz_hint(ap->ip);
 retry:
-	prod = align / mp->m_sb.sb_rextsize;
+	prod = xfs_extlen_to_rtxlen(mp, align);
 	error = xfs_bmap_extsize_align(mp, &ap->got, &ap->prev,
 					align, 1, ap->eof, 0,
 					ap->conv, &ap->offset, &ap->length);
@@ -117,17 +117,14 @@ xfs_bmap_rtalloc(
 		prod = 1;
 	/*
 	 * Set ralen to be the actual requested length in rtextents.
-	 */
-	ralen = ap->length / mp->m_sb.sb_rextsize;
-	/*
+	 *
 	 * If the old value was close enough to XFS_BMBT_MAX_EXTLEN that
 	 * we rounded up to it, cut it back so it's valid again.
 	 * Note that if it's a really large request (bigger than
 	 * XFS_BMBT_MAX_EXTLEN), we don't hear about that number, and can't
 	 * adjust the starting point to match it.
 	 */
-	if (xfs_rtxlen_to_extlen(mp, ralen) >= XFS_MAX_BMBT_EXTLEN)
-		ralen = XFS_MAX_BMBT_EXTLEN / mp->m_sb.sb_rextsize;
+	ralen = xfs_extlen_to_rtxlen(mp, min(ap->length, XFS_MAX_BMBT_EXTLEN));
 
 	/*
 	 * Lock out modifications to both the RT bitmap and summary inodes
@@ -164,7 +161,7 @@ xfs_bmap_rtalloc(
 		do_div(ap->blkno, mp->m_sb.sb_rextsize);
 	rtx = ap->blkno;
 	ap->length = ralen;
-	raminlen = max_t(xfs_extlen_t, 1, minlen / mp->m_sb.sb_rextsize);
+	raminlen = max_t(xfs_rtxlen_t, 1, xfs_extlen_to_rtxlen(mp, minlen));
 	error = xfs_rtallocate_extent(ap->tp, ap->blkno, raminlen, ap->length,
 			&ralen, ap->wasdel, prod, &rtx);
 	if (error)
diff --git a/fs/xfs/xfs_trans.c b/fs/xfs/xfs_trans.c
index 8c0bfc9a33b1..338dd3774507 100644
--- a/fs/xfs/xfs_trans.c
+++ b/fs/xfs/xfs_trans.c
@@ -24,6 +24,7 @@
 #include "xfs_dquot_item.h"
 #include "xfs_dquot.h"
 #include "xfs_icache.h"
+#include "xfs_rtbitmap.h"
 
 struct kmem_cache	*xfs_trans_cache;
 
@@ -1196,7 +1197,7 @@ xfs_trans_alloc_inode(
 
 retry:
 	error = xfs_trans_alloc(mp, resv, dblocks,
-			rblocks / mp->m_sb.sb_rextsize,
+			xfs_extlen_to_rtxlen(mp, rblocks),
 			force ? XFS_TRANS_RESERVE : 0, &tp);
 	if (error)
 		return error;

From 5dc3a80d46a450481df7f7e9fe673ba3eb4514c3 Mon Sep 17 00:00:00 2001
From: "Darrick J. Wong" <djwong@kernel.org>
Date: Mon, 16 Oct 2023 09:37:07 -0700
Subject: [PATCH 4/7] xfs: create helpers to convert rt block numbers to rt
 extent numbers

Create helpers to do unit conversions of rt block numbers to rt extent
numbers.  There are three variations -- one to compute the rt extent
number from an rt block number; one to compute the offset of an rt block
within an rt extent; and one to extract both.

Signed-off-by: Darrick J. Wong <djwong@kernel.org>
Reviewed-by: Christoph Hellwig <hch@lst.de>
---
 fs/xfs/libxfs/xfs_bmap.c     |  8 ++++----
 fs/xfs/libxfs/xfs_rtbitmap.c |  4 ++--
 fs/xfs/libxfs/xfs_rtbitmap.h | 31 +++++++++++++++++++++++++++++++
 3 files changed, 37 insertions(+), 6 deletions(-)

diff --git a/fs/xfs/libxfs/xfs_bmap.c b/fs/xfs/libxfs/xfs_bmap.c
index 19203699b992..fc96aa59a691 100644
--- a/fs/xfs/libxfs/xfs_bmap.c
+++ b/fs/xfs/libxfs/xfs_bmap.c
@@ -5276,7 +5276,6 @@ __xfs_bunmapi(
 	int			tmp_logflags;	/* partial logging flags */
 	int			wasdel;		/* was a delayed alloc extent */
 	int			whichfork;	/* data or attribute fork */
-	xfs_fsblock_t		sum;
 	xfs_filblks_t		len = *rlen;	/* length to unmap in file */
 	xfs_fileoff_t		end;
 	struct xfs_iext_cursor	icur;
@@ -5371,8 +5370,8 @@ __xfs_bunmapi(
 		if (!isrt)
 			goto delete;
 
-		sum = del.br_startblock + del.br_blockcount;
-		div_u64_rem(sum, mp->m_sb.sb_rextsize, &mod);
+		mod = xfs_rtb_to_rtxoff(mp,
+				del.br_startblock + del.br_blockcount);
 		if (mod) {
 			/*
 			 * Realtime extent not lined up at the end.
@@ -5419,7 +5418,8 @@ __xfs_bunmapi(
 				goto error0;
 			goto nodelete;
 		}
-		div_u64_rem(del.br_startblock, mp->m_sb.sb_rextsize, &mod);
+
+		mod = xfs_rtb_to_rtxoff(mp, del.br_startblock);
 		if (mod) {
 			xfs_extlen_t off = mp->m_sb.sb_rextsize - mod;
 
diff --git a/fs/xfs/libxfs/xfs_rtbitmap.c b/fs/xfs/libxfs/xfs_rtbitmap.c
index f64e4aeb393b..383c6437e042 100644
--- a/fs/xfs/libxfs/xfs_rtbitmap.c
+++ b/fs/xfs/libxfs/xfs_rtbitmap.c
@@ -1024,13 +1024,13 @@ xfs_rtfree_blocks(
 
 	ASSERT(rtlen <= XFS_MAX_BMBT_EXTLEN);
 
-	len = div_u64_rem(rtlen, mp->m_sb.sb_rextsize, &mod);
+	len = xfs_rtb_to_rtxrem(mp, rtlen, &mod);
 	if (mod) {
 		ASSERT(mod == 0);
 		return -EIO;
 	}
 
-	start = div_u64_rem(rtbno, mp->m_sb.sb_rextsize, &mod);
+	start = xfs_rtb_to_rtxrem(mp, rtbno, &mod);
 	if (mod) {
 		ASSERT(mod == 0);
 		return -EIO;
diff --git a/fs/xfs/libxfs/xfs_rtbitmap.h b/fs/xfs/libxfs/xfs_rtbitmap.h
index e2a36fc157c4..9df583083407 100644
--- a/fs/xfs/libxfs/xfs_rtbitmap.h
+++ b/fs/xfs/libxfs/xfs_rtbitmap.h
@@ -39,6 +39,37 @@ xfs_extlen_to_rtxlen(
 	return len / mp->m_sb.sb_rextsize;
 }
 
+/* Convert an rt block number into an rt extent number. */
+static inline xfs_rtxnum_t
+xfs_rtb_to_rtx(
+	struct xfs_mount	*mp,
+	xfs_rtblock_t		rtbno)
+{
+	return div_u64(rtbno, mp->m_sb.sb_rextsize);
+}
+
+/* Return the offset of an rt block number within an rt extent. */
+static inline xfs_extlen_t
+xfs_rtb_to_rtxoff(
+	struct xfs_mount	*mp,
+	xfs_rtblock_t		rtbno)
+{
+	return do_div(rtbno, mp->m_sb.sb_rextsize);
+}
+
+/*
+ * Crack an rt block number into an rt extent number and an offset within that
+ * rt extent.  Returns the rt extent number directly and the offset in @off.
+ */
+static inline xfs_rtxnum_t
+xfs_rtb_to_rtxrem(
+	struct xfs_mount	*mp,
+	xfs_rtblock_t		rtbno,
+	xfs_extlen_t		*off)
+{
+	return div_u64_rem(rtbno, mp->m_sb.sb_rextsize, off);
+}
+
 /*
  * Functions for walking free space rtextents in the realtime bitmap.
  */

From 055641248f649b52620a5fe8774bea253690e057 Mon Sep 17 00:00:00 2001
From: "Darrick J. Wong" <djwong@kernel.org>
Date: Mon, 16 Oct 2023 09:37:47 -0700
Subject: [PATCH 5/7] xfs: convert do_div calls to xfs_rtb_to_rtx helper calls

Convert these calls to use the helpers, and clean up all these places
where the same variable can have different units depending on where it
is in the function.

Signed-off-by: Darrick J. Wong <djwong@kernel.org>
Reviewed-by: Christoph Hellwig <hch@lst.de>
---
 fs/xfs/libxfs/xfs_bmap.c     |  8 ++------
 fs/xfs/libxfs/xfs_rtbitmap.h | 14 ++++++++++++++
 fs/xfs/scrub/rtbitmap.c      | 14 +++++---------
 fs/xfs/xfs_bmap_util.c       | 10 ++++------
 fs/xfs/xfs_fsmap.c           |  7 ++-----
 fs/xfs/xfs_rtalloc.c         |  3 +--
 6 files changed, 28 insertions(+), 28 deletions(-)

diff --git a/fs/xfs/libxfs/xfs_bmap.c b/fs/xfs/libxfs/xfs_bmap.c
index fc96aa59a691..be62acffad6c 100644
--- a/fs/xfs/libxfs/xfs_bmap.c
+++ b/fs/xfs/libxfs/xfs_bmap.c
@@ -4826,12 +4826,8 @@ xfs_bmap_del_extent_delay(
 	ASSERT(got->br_startoff <= del->br_startoff);
 	ASSERT(got_endoff >= del_endoff);
 
-	if (isrt) {
-		uint64_t	rtexts = del->br_blockcount;
-
-		do_div(rtexts, mp->m_sb.sb_rextsize);
-		xfs_mod_frextents(mp, rtexts);
-	}
+	if (isrt)
+		xfs_mod_frextents(mp, xfs_rtb_to_rtx(mp, del->br_blockcount));
 
 	/*
 	 * Update the inode delalloc counter now and wait to update the
diff --git a/fs/xfs/libxfs/xfs_rtbitmap.h b/fs/xfs/libxfs/xfs_rtbitmap.h
index 9df583083407..ff901bf3d1ee 100644
--- a/fs/xfs/libxfs/xfs_rtbitmap.h
+++ b/fs/xfs/libxfs/xfs_rtbitmap.h
@@ -70,6 +70,20 @@ xfs_rtb_to_rtxrem(
 	return div_u64_rem(rtbno, mp->m_sb.sb_rextsize, off);
 }
 
+/*
+ * Convert an rt block number into an rt extent number, rounding up to the next
+ * rt extent if the rt block is not aligned to an rt extent boundary.
+ */
+static inline xfs_rtxnum_t
+xfs_rtb_to_rtxup(
+	struct xfs_mount	*mp,
+	xfs_rtblock_t		rtbno)
+{
+	if (do_div(rtbno, mp->m_sb.sb_rextsize))
+		rtbno++;
+	return rtbno;
+}
+
 /*
  * Functions for walking free space rtextents in the realtime bitmap.
  */
diff --git a/fs/xfs/scrub/rtbitmap.c b/fs/xfs/scrub/rtbitmap.c
index 584a2b8badac..41a1d89ae8e6 100644
--- a/fs/xfs/scrub/rtbitmap.c
+++ b/fs/xfs/scrub/rtbitmap.c
@@ -128,26 +128,22 @@ xchk_rtbitmap(
 void
 xchk_xref_is_used_rt_space(
 	struct xfs_scrub	*sc,
-	xfs_rtblock_t		fsbno,
+	xfs_rtblock_t		rtbno,
 	xfs_extlen_t		len)
 {
 	xfs_rtxnum_t		startext;
 	xfs_rtxnum_t		endext;
-	xfs_rtxlen_t		extcount;
 	bool			is_free;
 	int			error;
 
 	if (xchk_skip_xref(sc->sm))
 		return;
 
-	startext = fsbno;
-	endext = fsbno + len - 1;
-	do_div(startext, sc->mp->m_sb.sb_rextsize);
-	do_div(endext, sc->mp->m_sb.sb_rextsize);
-	extcount = endext - startext + 1;
+	startext = xfs_rtb_to_rtx(sc->mp, rtbno);
+	endext = xfs_rtb_to_rtx(sc->mp, rtbno + len - 1);
 	xfs_ilock(sc->mp->m_rbmip, XFS_ILOCK_SHARED | XFS_ILOCK_RTBITMAP);
-	error = xfs_rtalloc_extent_is_free(sc->mp, sc->tp, startext, extcount,
-			&is_free);
+	error = xfs_rtalloc_extent_is_free(sc->mp, sc->tp, startext,
+			endext - startext + 1, &is_free);
 	if (!xchk_should_check_xref(sc, &error, NULL))
 		goto out_unlock;
 	if (is_free)
diff --git a/fs/xfs/xfs_bmap_util.c b/fs/xfs/xfs_bmap_util.c
index 4f53f784f06d..25a03c1276e3 100644
--- a/fs/xfs/xfs_bmap_util.c
+++ b/fs/xfs/xfs_bmap_util.c
@@ -156,14 +156,12 @@ xfs_bmap_rtalloc(
 	 * Realtime allocation, done through xfs_rtallocate_extent.
 	 */
 	if (ignore_locality)
-		ap->blkno = 0;
+		rtx = 0;
 	else
-		do_div(ap->blkno, mp->m_sb.sb_rextsize);
-	rtx = ap->blkno;
-	ap->length = ralen;
+		rtx = xfs_rtb_to_rtx(mp, ap->blkno);
 	raminlen = max_t(xfs_rtxlen_t, 1, xfs_extlen_to_rtxlen(mp, minlen));
-	error = xfs_rtallocate_extent(ap->tp, ap->blkno, raminlen, ap->length,
-			&ralen, ap->wasdel, prod, &rtx);
+	error = xfs_rtallocate_extent(ap->tp, rtx, raminlen, ralen, &ralen,
+			ap->wasdel, prod, &rtx);
 	if (error)
 		return error;
 
diff --git a/fs/xfs/xfs_fsmap.c b/fs/xfs/xfs_fsmap.c
index 1a187bc9da3d..5a72217f5feb 100644
--- a/fs/xfs/xfs_fsmap.c
+++ b/fs/xfs/xfs_fsmap.c
@@ -539,11 +539,8 @@ xfs_getfsmap_rtdev_rtbitmap(
 	 * Set up query parameters to return free rtextents covering the range
 	 * we want.
 	 */
-	alow.ar_startext = start_rtb;
-	ahigh.ar_startext = end_rtb;
-	do_div(alow.ar_startext, mp->m_sb.sb_rextsize);
-	if (do_div(ahigh.ar_startext, mp->m_sb.sb_rextsize))
-		ahigh.ar_startext++;
+	alow.ar_startext = xfs_rtb_to_rtx(mp, start_rtb);
+	ahigh.ar_startext = xfs_rtb_to_rtxup(mp, end_rtb);
 	error = xfs_rtalloc_query_range(mp, tp, &alow, &ahigh,
 			xfs_getfsmap_rtdev_rtbitmap_helper, info);
 	if (error)
diff --git a/fs/xfs/xfs_rtalloc.c b/fs/xfs/xfs_rtalloc.c
index 62faec195040..ac7c269ad547 100644
--- a/fs/xfs/xfs_rtalloc.c
+++ b/fs/xfs/xfs_rtalloc.c
@@ -1058,8 +1058,7 @@ xfs_growfs_rt(
 		nrblocks_step = (bmbno + 1) * NBBY * nsbp->sb_blocksize *
 				nsbp->sb_rextsize;
 		nsbp->sb_rblocks = min(nrblocks, nrblocks_step);
-		nsbp->sb_rextents = nsbp->sb_rblocks;
-		do_div(nsbp->sb_rextents, nsbp->sb_rextsize);
+		nsbp->sb_rextents = xfs_rtb_to_rtx(nmp, nsbp->sb_rblocks);
 		ASSERT(nsbp->sb_rextents != 0);
 		nsbp->sb_rextslog = xfs_highbit32(nsbp->sb_rextents);
 		nrsumlevels = nmp->m_rsumlevels = nsbp->sb_rextslog + 1;

From 5f57f7309d9ab9d24d50c5707472b1ed8af4eabc Mon Sep 17 00:00:00 2001
From: "Darrick J. Wong" <djwong@kernel.org>
Date: Mon, 16 Oct 2023 09:38:28 -0700
Subject: [PATCH 6/7] xfs: create rt extent rounding helpers for realtime
 extent blocks

Create a pair of functions to round rtblock numbers up or down to the
nearest rt extent.

Signed-off-by: Darrick J. Wong <djwong@kernel.org>
Reviewed-by: Christoph Hellwig <hch@lst.de>
---
 fs/xfs/libxfs/xfs_rtbitmap.h | 18 ++++++++++++++++++
 fs/xfs/xfs_bmap_util.c       |  8 +++-----
 2 files changed, 21 insertions(+), 5 deletions(-)

diff --git a/fs/xfs/libxfs/xfs_rtbitmap.h b/fs/xfs/libxfs/xfs_rtbitmap.h
index ff901bf3d1ee..ecf5645dd670 100644
--- a/fs/xfs/libxfs/xfs_rtbitmap.h
+++ b/fs/xfs/libxfs/xfs_rtbitmap.h
@@ -84,6 +84,24 @@ xfs_rtb_to_rtxup(
 	return rtbno;
 }
 
+/* Round this rtblock up to the nearest rt extent size. */
+static inline xfs_rtblock_t
+xfs_rtb_roundup_rtx(
+	struct xfs_mount	*mp,
+	xfs_rtblock_t		rtbno)
+{
+	return roundup_64(rtbno, mp->m_sb.sb_rextsize);
+}
+
+/* Round this rtblock down to the nearest rt extent size. */
+static inline xfs_rtblock_t
+xfs_rtb_rounddown_rtx(
+	struct xfs_mount	*mp,
+	xfs_rtblock_t		rtbno)
+{
+	return rounddown_64(rtbno, mp->m_sb.sb_rextsize);
+}
+
 /*
  * Functions for walking free space rtextents in the realtime bitmap.
  */
diff --git a/fs/xfs/xfs_bmap_util.c b/fs/xfs/xfs_bmap_util.c
index 25a03c1276e3..c640dfc2d00f 100644
--- a/fs/xfs/xfs_bmap_util.c
+++ b/fs/xfs/xfs_bmap_util.c
@@ -684,7 +684,7 @@ xfs_can_free_eofblocks(
 	 */
 	end_fsb = XFS_B_TO_FSB(mp, (xfs_ufsize_t)XFS_ISIZE(ip));
 	if (XFS_IS_REALTIME_INODE(ip) && mp->m_sb.sb_rextsize > 1)
-		end_fsb = roundup_64(end_fsb, mp->m_sb.sb_rextsize);
+		end_fsb = xfs_rtb_roundup_rtx(mp, end_fsb);
 	last_fsb = XFS_B_TO_FSB(mp, mp->m_super->s_maxbytes);
 	if (last_fsb <= end_fsb)
 		return false;
@@ -983,10 +983,8 @@ xfs_free_file_space(
 
 	/* We can only free complete realtime extents. */
 	if (XFS_IS_REALTIME_INODE(ip) && mp->m_sb.sb_rextsize > 1) {
-		startoffset_fsb = roundup_64(startoffset_fsb,
-					     mp->m_sb.sb_rextsize);
-		endoffset_fsb = rounddown_64(endoffset_fsb,
-					     mp->m_sb.sb_rextsize);
+		startoffset_fsb = xfs_rtb_roundup_rtx(mp, startoffset_fsb);
+		endoffset_fsb = xfs_rtb_rounddown_rtx(mp, endoffset_fsb);
 	}
 
 	/*

From ef5a83b7e597038d1c734ddb4bc00638082c2bf1 Mon Sep 17 00:00:00 2001
From: "Darrick J. Wong" <djwong@kernel.org>
Date: Mon, 16 Oct 2023 09:40:11 -0700
Subject: [PATCH 7/7] xfs: use shifting and masking when converting rt extents,
 if possible

Avoid the costs of integer division (32-bit and 64-bit) if the realtime
extent size is a power of two.

Signed-off-by: Darrick J. Wong <djwong@kernel.org>
Reviewed-by: Christoph Hellwig <hch@lst.de>
---
 fs/xfs/libxfs/xfs_rtbitmap.h | 29 +++++++++++++++++++++++++++++
 fs/xfs/libxfs/xfs_sb.c       |  2 ++
 fs/xfs/xfs_linux.h           | 12 ++++++++++++
 fs/xfs/xfs_mount.h           |  2 ++
 fs/xfs/xfs_rtalloc.c         |  1 +
 fs/xfs/xfs_trans.c           |  4 ++++
 6 files changed, 50 insertions(+)

diff --git a/fs/xfs/libxfs/xfs_rtbitmap.h b/fs/xfs/libxfs/xfs_rtbitmap.h
index ecf5645dd670..3686a53e0aed 100644
--- a/fs/xfs/libxfs/xfs_rtbitmap.h
+++ b/fs/xfs/libxfs/xfs_rtbitmap.h
@@ -11,6 +11,9 @@ xfs_rtx_to_rtb(
 	struct xfs_mount	*mp,
 	xfs_rtxnum_t		rtx)
 {
+	if (mp->m_rtxblklog >= 0)
+		return rtx << mp->m_rtxblklog;
+
 	return rtx * mp->m_sb.sb_rextsize;
 }
 
@@ -19,6 +22,9 @@ xfs_rtxlen_to_extlen(
 	struct xfs_mount	*mp,
 	xfs_rtxlen_t		rtxlen)
 {
+	if (mp->m_rtxblklog >= 0)
+		return rtxlen << mp->m_rtxblklog;
+
 	return rtxlen * mp->m_sb.sb_rextsize;
 }
 
@@ -28,6 +34,9 @@ xfs_extlen_to_rtxmod(
 	struct xfs_mount	*mp,
 	xfs_extlen_t		len)
 {
+	if (mp->m_rtxblklog >= 0)
+		return len & mp->m_rtxblkmask;
+
 	return len % mp->m_sb.sb_rextsize;
 }
 
@@ -36,6 +45,9 @@ xfs_extlen_to_rtxlen(
 	struct xfs_mount	*mp,
 	xfs_extlen_t		len)
 {
+	if (mp->m_rtxblklog >= 0)
+		return len >> mp->m_rtxblklog;
+
 	return len / mp->m_sb.sb_rextsize;
 }
 
@@ -45,6 +57,9 @@ xfs_rtb_to_rtx(
 	struct xfs_mount	*mp,
 	xfs_rtblock_t		rtbno)
 {
+	if (likely(mp->m_rtxblklog >= 0))
+		return rtbno >> mp->m_rtxblklog;
+
 	return div_u64(rtbno, mp->m_sb.sb_rextsize);
 }
 
@@ -54,6 +69,9 @@ xfs_rtb_to_rtxoff(
 	struct xfs_mount	*mp,
 	xfs_rtblock_t		rtbno)
 {
+	if (likely(mp->m_rtxblklog >= 0))
+		return rtbno & mp->m_rtxblkmask;
+
 	return do_div(rtbno, mp->m_sb.sb_rextsize);
 }
 
@@ -67,6 +85,11 @@ xfs_rtb_to_rtxrem(
 	xfs_rtblock_t		rtbno,
 	xfs_extlen_t		*off)
 {
+	if (likely(mp->m_rtxblklog >= 0)) {
+		*off = rtbno & mp->m_rtxblkmask;
+		return rtbno >> mp->m_rtxblklog;
+	}
+
 	return div_u64_rem(rtbno, mp->m_sb.sb_rextsize, off);
 }
 
@@ -79,6 +102,12 @@ xfs_rtb_to_rtxup(
 	struct xfs_mount	*mp,
 	xfs_rtblock_t		rtbno)
 {
+	if (likely(mp->m_rtxblklog >= 0)) {
+		if (rtbno & mp->m_rtxblkmask)
+			return (rtbno >> mp->m_rtxblklog) + 1;
+		return rtbno >> mp->m_rtxblklog;
+	}
+
 	if (do_div(rtbno, mp->m_sb.sb_rextsize))
 		rtbno++;
 	return rtbno;
diff --git a/fs/xfs/libxfs/xfs_sb.c b/fs/xfs/libxfs/xfs_sb.c
index 6264daaab37b..1f74d0cd1618 100644
--- a/fs/xfs/libxfs/xfs_sb.c
+++ b/fs/xfs/libxfs/xfs_sb.c
@@ -975,6 +975,8 @@ xfs_sb_mount_common(
 	mp->m_blockmask = sbp->sb_blocksize - 1;
 	mp->m_blockwsize = sbp->sb_blocksize >> XFS_WORDLOG;
 	mp->m_blockwmask = mp->m_blockwsize - 1;
+	mp->m_rtxblklog = log2_if_power2(sbp->sb_rextsize);
+	mp->m_rtxblkmask = mask64_if_power2(sbp->sb_rextsize);
 
 	mp->m_alloc_mxr[0] = xfs_allocbt_maxrecs(mp, sbp->sb_blocksize, 1);
 	mp->m_alloc_mxr[1] = xfs_allocbt_maxrecs(mp, sbp->sb_blocksize, 0);
diff --git a/fs/xfs/xfs_linux.h b/fs/xfs/xfs_linux.h
index e9d317a3dafe..d7873e0360f0 100644
--- a/fs/xfs/xfs_linux.h
+++ b/fs/xfs/xfs_linux.h
@@ -198,6 +198,18 @@ static inline uint64_t howmany_64(uint64_t x, uint32_t y)
 	return x;
 }
 
+/* If @b is a power of 2, return log2(b).  Else return -1. */
+static inline int8_t log2_if_power2(unsigned long b)
+{
+	return is_power_of_2(b) ? ilog2(b) : -1;
+}
+
+/* If @b is a power of 2, return a mask of the lower bits, else return zero. */
+static inline unsigned long long mask64_if_power2(unsigned long b)
+{
+	return is_power_of_2(b) ? b - 1 : 0;
+}
+
 int xfs_rw_bdev(struct block_device *bdev, sector_t sector, unsigned int count,
 		char *data, enum req_op op);
 
diff --git a/fs/xfs/xfs_mount.h b/fs/xfs/xfs_mount.h
index d19cca099bc3..d8769dc5f6dd 100644
--- a/fs/xfs/xfs_mount.h
+++ b/fs/xfs/xfs_mount.h
@@ -119,6 +119,7 @@ typedef struct xfs_mount {
 	uint8_t			m_blkbb_log;	/* blocklog - BBSHIFT */
 	uint8_t			m_agno_log;	/* log #ag's */
 	uint8_t			m_sectbb_log;	/* sectlog - BBSHIFT */
+	int8_t			m_rtxblklog;	/* log2 of rextsize, if possible */
 	uint			m_blockmask;	/* sb_blocksize-1 */
 	uint			m_blockwsize;	/* sb_blocksize in words */
 	uint			m_blockwmask;	/* blockwsize-1 */
@@ -152,6 +153,7 @@ typedef struct xfs_mount {
 	uint64_t		m_features;	/* active filesystem features */
 	uint64_t		m_low_space[XFS_LOWSP_MAX];
 	uint64_t		m_low_rtexts[XFS_LOWSP_MAX];
+	uint64_t		m_rtxblkmask;	/* rt extent block mask */
 	struct xfs_ino_geometry	m_ino_geo;	/* inode geometry */
 	struct xfs_trans_resv	m_resv;		/* precomputed res values */
 						/* low free space thresholds */
diff --git a/fs/xfs/xfs_rtalloc.c b/fs/xfs/xfs_rtalloc.c
index ac7c269ad547..e5a3200cea72 100644
--- a/fs/xfs/xfs_rtalloc.c
+++ b/fs/xfs/xfs_rtalloc.c
@@ -1054,6 +1054,7 @@ xfs_growfs_rt(
 		 * Calculate new sb and mount fields for this round.
 		 */
 		nsbp->sb_rextsize = in->extsize;
+		nmp->m_rtxblklog = -1; /* don't use shift or masking */
 		nsbp->sb_rbmblocks = bmbno + 1;
 		nrblocks_step = (bmbno + 1) * NBBY * nsbp->sb_blocksize *
 				nsbp->sb_rextsize;
diff --git a/fs/xfs/xfs_trans.c b/fs/xfs/xfs_trans.c
index 338dd3774507..305c9d07bf1b 100644
--- a/fs/xfs/xfs_trans.c
+++ b/fs/xfs/xfs_trans.c
@@ -656,6 +656,10 @@ xfs_trans_unreserve_and_mod_sb(
 	mp->m_sb.sb_agcount += tp->t_agcount_delta;
 	mp->m_sb.sb_imax_pct += tp->t_imaxpct_delta;
 	mp->m_sb.sb_rextsize += tp->t_rextsize_delta;
+	if (tp->t_rextsize_delta) {
+		mp->m_rtxblklog = log2_if_power2(mp->m_sb.sb_rextsize);
+		mp->m_rtxblkmask = mask64_if_power2(mp->m_sb.sb_rextsize);
+	}
 	mp->m_sb.sb_rbmblocks += tp->t_rbmblocks_delta;
 	mp->m_sb.sb_rblocks += tp->t_rblocks_delta;
 	mp->m_sb.sb_rextents += tp->t_rextents_delta;