Date: Thu, 10 Jan 2002 01:29:53 +0000 From: Ian Dowse <iedowse@maths.tcd.ie> To: Mike Silbersack <silby@silby.com> Cc: cvs-committers@FreeBSD.org, cvs-all@FreeBSD.org Subject: Re: cvs commit: src/sys/boot/i386/boot2 boot2.c Message-ID: <200201100129.aa00865@salmon.maths.tcd.ie> In-Reply-To: Your message of "Wed, 09 Jan 2002 17:14:36 GMT." <200201091714.aa02189@salmon.maths.tcd.ie>
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In message <200201091714.aa02189@salmon.maths.tcd.ie>, Ian Dowse writes:
>In fact,
>a much better approach would be to change the code so that it reads
>large blocks in fixed-sized chunks. I'll see if that can be done
>without too much additional code-bloat.
This turned out to be relatively easy to do and it actually reduces
the size of boot2 by 92 bytes, mainly because the simple malloc()
function is no longer needed. It uses 4k buffers regardless of the
filesystem block size (4k is the minumum ffs block size), so it
should work with any block size.
Ian
Index: boot2/boot2.c
===================================================================
RCS file: /dump/FreeBSD-CVS/src/sys/boot/i386/boot2/boot2.c,v
retrieving revision 1.34
diff -u -r1.34 boot2.c
--- boot2/boot2.c 9 Jan 2002 15:46:17 -0000 1.34
+++ boot2/boot2.c 10 Jan 2002 00:53:30 -0000
@@ -57,13 +57,28 @@
#define ARGS 0x900
#define NOPT 11
-#define BSIZEMAX 16384
#define NDEV 5
#define MEM_BASE 0x12
#define MEM_EXT 0x15
#define V86_CY(x) ((x) & 1)
#define V86_ZR(x) ((x) & 0x40)
+/*
+ * We use 4k `virtual' blocks for filesystem data, whatever the actual
+ * filesystem block size. FFS blocks are always a multiple of 4k.
+ */
+#define VBLKSIZE 4096
+#define VBLKMASK (VBLKSIZE - 1)
+#define DBPERVBLK (VBLKSIZE / DEV_BSIZE)
+#define IPERVBLK (VBLKSIZE / sizeof(struct dinode))
+#define INDIRPERVBLK (VBLKSIZE / sizeof(ufs_daddr_t))
+#define INO_TO_VBA(fs, x) (fsbtodb(fs, ino_to_fsba(fs, x)) + \
+ (ino_to_fsbo(fs, x) / IPERVBLK) * DBPERVBLK)
+#define INO_TO_VBO(fs, x) (ino_to_fsbo(fs, x) % IPERVBLK)
+#define FS_TO_VBA(fs, fsb, off) (fsbtodb(fs, fsb) + \
+ ((off) / VBLKSIZE) * DBPERVBLK)
+#define FS_TO_VBO(fs, fsb, off) ((off) & VBLKMASK)
+
#define DRV_HARD 0x80
#define DRV_MASK 0x7f
@@ -121,7 +136,6 @@
static int printf(const char *,...);
static int putchar(int);
static void *memcpy(void *, const void *, size_t);
-static void *malloc(size_t);
static uint32_t memsize(int);
static int drvread(void *, unsigned, unsigned);
static int keyhit(unsigned);
@@ -516,38 +530,34 @@
static ssize_t
fsread(ino_t inode, void *buf, size_t nbyte)
{
- static struct fs fs;
+ static char blkbuf[VBLKSIZE];
+ static ufs_daddr_t indbuf[VBLKSIZE / sizeof(ufs_daddr_t)];
+ static char sbbuf[SBSIZE];
static struct dinode din;
- static char *blkbuf;
- static ufs_daddr_t *indbuf;
+ static struct fs *fs = (struct fs *)sbbuf;
static ino_t inomap;
- static ufs_daddr_t blkmap, indmap;
- static unsigned fsblks;
+ static daddr_t blkmap, indmap;
char *s;
ufs_daddr_t lbn, addr;
- size_t n, nb, off;
+ daddr_t vbaddr;
+ size_t n, nb, off, vboff;
if (!dsk.meta) {
- if (!blkbuf)
- blkbuf = malloc(BSIZEMAX);
inomap = 0;
- if (dskread(blkbuf, SBOFF / DEV_BSIZE, SBSIZE / DEV_BSIZE))
+ if (dskread(sbbuf, SBOFF / DEV_BSIZE, SBSIZE / DEV_BSIZE))
return -1;
- memcpy(&fs, blkbuf, sizeof(fs));
- if (fs.fs_magic != FS_MAGIC) {
+ if (fs->fs_magic != FS_MAGIC) {
printf("Not ufs\n");
return -1;
}
- fsblks = fs.fs_bsize >> DEV_BSHIFT;
dsk.meta++;
}
if (!inode)
return 0;
if (inomap != inode) {
- if (dskread(blkbuf, fsbtodb(&fs, ino_to_fsba(&fs, inode)),
- fsblks))
+ if (dskread(blkbuf, INO_TO_VBA(fs, inode), DBPERVBLK))
return -1;
- din = ((struct dinode *)blkbuf)[inode % INOPB(&fs)];
+ din = ((struct dinode *)blkbuf)[INO_TO_VBO(fs, inode)];
inomap = inode;
fs_off = 0;
blkmap = indmap = 0;
@@ -557,31 +567,34 @@
nbyte = n;
nb = nbyte;
while (nb) {
- lbn = lblkno(&fs, fs_off);
+ lbn = lblkno(fs, fs_off);
+ off = blkoff(fs, fs_off);
if (lbn < NDADDR)
addr = din.di_db[lbn];
else {
- if (indmap != din.di_ib[0]) {
- if (!indbuf)
- indbuf = malloc(BSIZEMAX);
- if (dskread(indbuf, fsbtodb(&fs, din.di_ib[0]),
- fsblks))
+ vbaddr = FS_TO_VBA(fs, din.di_ib[0], sizeof(indbuf[0]) *
+ ((lbn - NDADDR) % NINDIR(fs)));
+ if (indmap != vbaddr) {
+ if (dskread(indbuf, vbaddr, DBPERVBLK))
return -1;
- indmap = din.di_ib[0];
+ indmap = vbaddr;
}
- addr = indbuf[(lbn - NDADDR) % NINDIR(&fs)];
+ addr = indbuf[(lbn - NDADDR) % INDIRPERVBLK];
}
- n = dblksize(&fs, &din, lbn);
- if (blkmap != addr) {
- if (dskread(blkbuf, fsbtodb(&fs, addr), n >> DEV_BSHIFT))
+ vbaddr = FS_TO_VBA(fs, addr, off);
+ vboff = FS_TO_VBO(fs, addr, off);
+ n = dblksize(fs, &din, lbn) - (off & ~VBLKMASK);
+ if (n > VBLKSIZE)
+ n = VBLKSIZE;
+ if (blkmap != vbaddr) {
+ if (dskread(blkbuf, vbaddr, n >> DEV_BSHIFT))
return -1;
- blkmap = addr;
+ blkmap = vbaddr;
}
- off = blkoff(&fs, fs_off);
- n -= off;
+ n -= vboff;
if (n > nb)
n = nb;
- memcpy(s, blkbuf + off, n);
+ memcpy(s, blkbuf + vboff, n);
s += n;
fs_off += n;
nb -= n;
@@ -592,14 +605,12 @@
static int
dskread(void *buf, unsigned lba, unsigned nblk)
{
- static char *sec;
+ static char sec[DEV_BSIZE];
struct dos_partition *dp;
struct disklabel *d;
unsigned sl, i;
if (!dsk.meta) {
- if (!sec)
- sec = malloc(DEV_BSIZE);
dsk.start = 0;
if (drvread(sec, DOSBBSECTOR, 1))
return -1;
@@ -709,19 +720,6 @@
for (d = dst, s = src; size; size--)
*d++ = *s++;
return dst;
-}
-
-static void *
-malloc(size_t size)
-{
- static uint32_t next;
- void *p;
-
- if (!next)
- next = roundup2(__base + _end, 0x10000) - __base;
- p = (void *)next;
- next += size;
- return p;
}
static uint32_t
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