Author: delphij
Date: Sat Jul 18 23:11:40 2020
New Revision: 363314
URL: https://svnweb.freebsd.org/changeset/base/363314
Log:
MFC r362936: Gather writes to larger chunks (MAXPHYS) instead of issuing
them in sectors.
Modified:
stable/11/sbin/newfs_msdos/mkfs_msdos.c
Directory Properties:
stable/11/ (props changed)
Modified: stable/11/sbin/newfs_msdos/mkfs_msdos.c
==============================================================================
--- stable/11/sbin/newfs_msdos/mkfs_msdos.c Sat Jul 18 23:05:16 2020
(r363313)
+++ stable/11/sbin/newfs_msdos/mkfs_msdos.c Sat Jul 18 23:11:40 2020
(r363314)
@@ -59,6 +59,7 @@ static const char rcsid[] =
#define DOSMAGIC 0xaa55 /* DOS magic number */
#define MINBPS 512 /* minimum bytes per sector */
+#define MAXBPS 4096 /* maximum bytes per sector */
#define MAXSPC 128 /* maximum sectors per cluster */
#define MAXNFT 16 /* maximum number of FATs */
#define DEFBLK 4096 /* default block size */
@@ -72,6 +73,25 @@ static const char rcsid[] =
#define MAXCLS16 0xfff4U /* maximum FAT16 clusters */
#define MAXCLS32 0xffffff4U /* maximum FAT32 clusters */
+#ifndef CTASSERT
+#define CTASSERT(x) _CTASSERT(x, __LINE__)
+#define _CTASSERT(x, y) __CTASSERT(x, y)
+#define __CTASSERT(x, y) typedef char __assert_ ## y [(x) ? 1 :
-1]
+#endif
+
+/*
+ * For better performance, we want to write larger chunks instead of
+ * individual sectors (the size can only be 512, 1024, 2048 or 4096
+ * bytes). Assert that MAXPHYS can always hold an integer number of
+ * sectors by asserting that both are power of two numbers and the
+ * MAXPHYS is greater than MAXBPS.
+ */
+CTASSERT(powerof2(MAXPHYS));
+CTASSERT(powerof2(MAXBPS));
+CTASSERT(MAXPHYS > MAXBPS);
+
+const static ssize_t chunksize = MAXPHYS;
+
#define mincls(fat) ((fat) == 12 ? MINCLS12 : \
(fat) == 16 ? MINCLS16 : \
MINCLS32)
@@ -238,6 +258,7 @@ mkfs_msdos(const char *fname, const char *dtype, const
struct bsx *bsx;
struct de *de;
u_int8_t *img;
+ u_int8_t *physbuf, *physbuf_end;
const char *bname;
ssize_t n;
time_t now;
@@ -247,7 +268,7 @@ mkfs_msdos(const char *fname, const char *dtype, const
int fd, fd1, rv;
struct msdos_options o = *op;
- img = NULL;
+ physbuf = NULL;
rv = -1;
fd = fd1 = -1;
@@ -332,15 +353,13 @@ mkfs_msdos(const char *fname, const char *dtype, const
bpb.bpbSecPerClust = 64; /* otherwise 32k */
}
}
- if (!powerof2(bpb.bpbBytesPerSec)) {
- warnx("bytes/sector (%u) is not a power of 2", bpb.bpbBytesPerSec);
+ if (bpb.bpbBytesPerSec < MINBPS ||
+ bpb.bpbBytesPerSec > MAXBPS ||
+ !powerof2(bpb.bpbBytesPerSec)) {
+ warnx("Invalid bytes/sector (%u): must be 512, 1024, 2048 or 4096",
+ bpb.bpbBytesPerSec);
goto done;
}
- if (bpb.bpbBytesPerSec < MINBPS) {
- warnx("bytes/sector (%u) is too small; minimum is %u",
- bpb.bpbBytesPerSec, MINBPS);
- goto done;
- }
if (o.volume_label && !oklabel(o.volume_label)) {
warnx("%s: bad volume label", o.volume_label);
@@ -610,11 +629,14 @@ mkfs_msdos(const char *fname, const char *dtype, const
tm = localtime(&now);
}
-
- if (!(img = malloc(bpb.bpbBytesPerSec))) {
+ physbuf = malloc(chunksize);
+ if (physbuf == NULL) {
warn(NULL);
goto done;
}
+ physbuf_end = physbuf + chunksize;
+ img = physbuf;
+
dir = bpb.bpbResSectors + (bpb.bpbFATsecs ? bpb.bpbFATsecs :
bpb.bpbBigFATsecs) * bpb.bpbFATs;
memset(&si_sa, 0, sizeof(si_sa));
@@ -737,19 +759,37 @@ mkfs_msdos(const char *fname, const char *dtype, const
(u_int)tm->tm_mday;
mk2(de->deMDate, x);
}
- if ((n = write(fd, img, bpb.bpbBytesPerSec)) == -1) {
- warn("%s", fname);
- goto done;
+ /*
+ * Issue a write of chunksize once we have collected
+ * enough sectors.
+ */
+ img += bpb.bpbBytesPerSec;
+ if (img >= physbuf_end) {
+ n = write(fd, physbuf, chunksize);
+ if (n != chunksize) {
+ warnx("%s: can't write sector %u", fname, lsn);
+ goto done;
+ }
+ img = physbuf;
}
- if ((unsigned)n != bpb.bpbBytesPerSec) {
- warnx("%s: can't write sector %u", fname, lsn);
- goto done;
- }
}
+ /*
+ * Write remaining sectors, if the last write didn't end
+ * up filling a whole chunk.
+ */
+ if (img != physbuf) {
+ ssize_t tailsize = img - physbuf;
+
+ n = write(fd, physbuf, tailsize);
+ if (n != tailsize) {
+ warnx("%s: can't write sector %u", fname, lsn);
+ goto done;
+ }
+ }
}
rv = 0;
done:
- free(img);
+ free(physbuf);
if (fd != -1)
close(fd);
if (fd1 != -1)
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