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>
---
fs/xfs/libxfs/xfs_rtbitmap.h | 20 ++++++++++++++++++++
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, 41 insertions(+)
diff --git a/fs/xfs/libxfs/xfs_rtbitmap.h b/fs/xfs/libxfs/xfs_rtbitmap.h
index bc51d3bfc7c45..9dd791181ca2b 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 +57,11 @@ xfs_rtb_to_rtx(
xfs_rtblock_t rtbno,
xfs_extlen_t *mod)
{
+ if (mp->m_rtxblklog >= 0) {
+ *mod = rtbno & mp->m_rtxblkmask;
+ return rtbno >> mp->m_rtxblklog;
+ }
+
return div_u64_rem(rtbno, mp->m_sb.sb_rextsize, mod);
}
@@ -53,6 +70,9 @@ xfs_rtb_to_rtxt(
struct xfs_mount *mp,
xfs_rtblock_t rtbno)
{
+ if (mp->m_rtxblklog >= 0)
+ return rtbno >> mp->m_rtxblklog;
+
return div_u64(rtbno, mp->m_sb.sb_rextsize);
}
diff --git a/fs/xfs/libxfs/xfs_sb.c b/fs/xfs/libxfs/xfs_sb.c
index 5fb142b8e3d92..db04378f287a6 100644
--- a/fs/xfs/libxfs/xfs_sb.c
+++ b/fs/xfs/libxfs/xfs_sb.c
@@ -1011,6 +1011,8 @@ 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 dfde4021905b7..953466922ddf7 100644
--- a/fs/xfs/xfs_linux.h
+++ b/fs/xfs/xfs_linux.h
@@ -203,6 +203,18 @@ static inline bool isaligned_64(uint64_t x, uint32_t y)
return do_div(x, y) == 0;
}
+/* 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 f42679a6569ff..3c5b0327164bc 100644
--- a/fs/xfs/xfs_mount.h
+++ b/fs/xfs/xfs_mount.h
@@ -120,6 +120,7 @@ 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 */
@@ -153,6 +154,7 @@ 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 e62ca51b995ba..dc4874776c2cb 100644
--- a/fs/xfs/xfs_rtalloc.c
+++ b/fs/xfs/xfs_rtalloc.c
@@ -1052,6 +1052,7 @@ 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 22aa2111b6cab..35161074c4e7d 100644
--- a/fs/xfs/xfs_trans.c
+++ b/fs/xfs/xfs_trans.c
@@ -712,6 +712,10 @@ 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;
