From: Darrick J. Wong <djwong@xxxxxxxxxx>
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@xxxxxxxxxx>
Reviewed-by: Christoph Hellwig <hch@xxxxxx>
---
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;
