add initialization comments; init for maxcontig and maxbpg

SCCS-vsn: sbin/newfs/mkfs.c 2.5

diff --git a/usr/src/sbin/newfs/mkfs.c b/usr/src/sbin/newfs/mkfs.c
index dca3e2c..45a57ef 100644 (file)
--- a/usr/src/sbin/newfs/mkfs.c
+++ b/usr/src/sbin/newfs/mkfs.c
@@ -1,4 +1,4 @@
-static char *sccsid = "@(#)mkfs.c      2.4 (Berkeley) %G%";
+static char *sccsid = "@(#)mkfs.c      2.5 (Berkeley) %G%";

 
 /*
  * make file system for cylinder-group style file systems
 
 /*
  * make file system for cylinder-group style file systems


@@ -6,6 +6,72 @@ static char *sccsid = "@(#)mkfs.c      2.4 (Berkeley) %G%";
  * usage: mkfs special size [ nsect ntrak bsize fsize cpg ]
  */
 
  * usage: mkfs special size [ nsect ntrak bsize fsize cpg ]
  */
 

+/*
+ * The following constants set the defaults used for the number
+ * of sectors (fs_nsect), and number of tracks (fs_ntrak).
+ */
+#define DFLNSECT       32
+#define DFLNTRAK       16
+
+/*
+ * The following two constants set the default block and fragment sizes.
+ * Both constants must be a power of 2 and meet the following constraints:
+ *     MINBSIZE <= DESBLKSIZE <= MAXBSIZE
+ *     DEV_BSIZE <= DESFRAGSIZE <= DESBLKSIZE
+ *     DESBLKSIZE / DESFRAGSIZE <= 8
+ */
+#define DESBLKSIZE     8192
+#define DESFRAGSIZE    1024
+
+/*
+ * Cylinder groups may have up to MAXCPG cylinders. The actual
+ * number used depends upon how much information can be stored
+ * on a single cylinder. The default is to used 16 cylinders
+ * per group.
+ */
+#define        DESCPG          16      /* desired fs_cpg */
+
+/*
+ * MINFREE gives the minimum acceptable percentage of file system
+ * blocks which may be free. If the freelist drops below this level
+ * only the superuser may continue to allocate blocks. This may
+ * be set to 0 if no reserve of free blocks is deemed necessary,
+ * however throughput drops by fifty percent if the file system
+ * is run at between 90% and 100% full; thus the default value of
+ * fs_minfree is 10%.
+ */
+#define MINFREE                10
+
+/*
+ * ROTDELAY gives the minimum number of milliseconds to initiate
+ * another disk transfer on the same cylinder. It is used in
+ * determining the rotationally optimal layout for disk blocks
+ * within a file; the default of fs_rotdelay is 2ms.
+ */
+#define ROTDELAY       2
+
+/*
+ * MAXCONTIG sets the default for the maximum number of blocks
+ * that may be allocated sequentially. Since UNIX drivers are
+ * not capable of scheduling multi-block transfers, this defaults
+ * to 1 (ie no contiguous blocks are allocated).
+ */
+#define MAXCONTIG      1
+
+/*
+ * MAXBLKPG determines the maximum number of data blocks which are
+ * placed in a single cylinder group. This is currently a function
+ * of the block and fragment size of the file system.
+ */
+#define MAXBLKPG(fs)   ((fs)->fs_fsize / sizeof(daddr_t))
+
+/*
+ * Each file system has a number of inodes statically allocated.
+ * We allocate one inode slot per NBPI bytes, expecting this
+ * to be far more than we will ever need.
+ */
+#define        NBPI            2048
+

 #ifndef STANDALONE
 #include <stdio.h>
 #include <a.out.h>
 #ifndef STANDALONE
 #include <stdio.h>
 #include <a.out.h>


@@ -113,11 +179,11 @@ main(argc, argv)
        if (argc > 4)
                sblock.fs_bsize = atoi(argv[4]);
        else
        if (argc > 4)
                sblock.fs_bsize = atoi(argv[4]);
        else

-               sblock.fs_bsize = MAXBSIZE;
+               sblock.fs_bsize = DESBLKSIZE;

        if (argc > 5)
                sblock.fs_fsize = atoi(argv[5]);
        else
        if (argc > 5)
                sblock.fs_fsize = atoi(argv[5]);
        else

-               sblock.fs_fsize = MAX(sblock.fs_bsize / DESFRAG, DEV_BSIZE);
+               sblock.fs_fsize = DESFRAGSIZE;

        if (!POWEROF2(sblock.fs_bsize)) {
                printf("block size must be a power of 2, not %d\n",
                    sblock.fs_bsize);
        if (!POWEROF2(sblock.fs_bsize)) {
                printf("block size must be a power of 2, not %d\n",
                    sblock.fs_bsize);


@@ -351,6 +417,8 @@ next:
        sblock.fs_magic = FS_MAGIC;
        sblock.fs_rotdelay = ROTDELAY;
        sblock.fs_minfree = MINFREE;
        sblock.fs_magic = FS_MAGIC;
        sblock.fs_rotdelay = ROTDELAY;
        sblock.fs_minfree = MINFREE;

+       sblock.fs_maxcontig = MAXCONTIG;
+       sblock.fs_maxbpg = MAXBLKPG(&sblock);

        sblock.fs_rps = 60;     /* assume disk speed == 60 HZ */
        sblock.fs_cgrotor = 0;
        sblock.fs_cstotal.cs_ndir = 0;
        sblock.fs_rps = 60;     /* assume disk speed == 60 HZ */
        sblock.fs_cgrotor = 0;
        sblock.fs_cstotal.cs_ndir = 0;