I've put together a patch to reduce the size of the minix superblock by
dynamically allocating the buffer arrays it needs. This reduces its size
from the largest superblock down to a more modest size, and will save a
page or two of non-swappable memory for the superblock array.
The patch also moves the error cleanup in read_super off of the common
execution path, and corrects a problem with a couple of error exits that
would leave a number of buffers in use.
I don't have any minix filesystems here to test with, so I'd appreiciate
it if some minix users could give this a try and let me know if it
works.
Regards,
Bill
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Content-Type: text/plain; charset=us-ascii; name="minix_79-patch"
Content-Transfer-Encoding: 7bit
Content-Disposition: inline; filename="minix_79-patch"
--- linux-2.1.79/include/linux/minix_fs_sb.h.old Thu Jan 4 07:07:58 1996
+++ linux-2.1.79/include/linux/minix_fs_sb.h Thu Jan 15 16:39:41 1998
@@ -12,10 +12,10 @@
unsigned long s_firstdatazone;
unsigned long s_log_zone_size;
unsigned long s_max_size;
- struct buffer_head * s_imap[8];
- struct buffer_head * s_zmap[64];
unsigned long s_dirsize;
unsigned long s_namelen;
+ struct buffer_head ** s_imap;
+ struct buffer_head ** s_zmap;
struct buffer_head * s_sbh;
struct minix_super_block * s_ms;
unsigned short s_mount_state;
--- linux-2.1.79/fs/minix/inode.c.old Fri Jul 18 15:42:29 1997
+++ linux-2.1.79/fs/minix/inode.c Thu Jan 15 17:39:39 1998
@@ -12,9 +12,9 @@
#include <linux/module.h>
#include <linux/sched.h>
-#include <linux/minix_fs.h>
#include <linux/kernel.h>
#include <linux/mm.h>
+#include <linux/malloc.h>
#include <linux/string.h>
#include <linux/stat.h>
#include <linux/locks.h>
@@ -24,6 +24,8 @@
#include <asm/uaccess.h>
#include <asm/bitops.h>
+#include <linux/minix_fs.h>
+
static void minix_delete_inode(struct inode *inode)
{
inode->i_size = 0;
@@ -62,12 +64,13 @@
sb->u.minix_sb.s_ms->s_state = sb->u.minix_sb.s_mount_state;
mark_buffer_dirty(sb->u.minix_sb.s_sbh, 1);
}
- sb->s_dev = 0;
for(i = 0 ; i < MINIX_I_MAP_SLOTS ; i++)
brelse(sb->u.minix_sb.s_imap[i]);
for(i = 0 ; i < MINIX_Z_MAP_SLOTS ; i++)
brelse(sb->u.minix_sb.s_zmap[i]);
brelse (sb->u.minix_sb.s_sbh);
+ kfree(sb->u.minix_sb.s_imap);
+ sb->s_dev = 0;
unlock_super(sb);
MOD_DEC_USE_COUNT;
return;
@@ -161,30 +164,29 @@
return errmsg;
}
-struct super_block *minix_read_super(struct super_block *s,void *data,
+struct super_block *minix_read_super(struct super_block *s, void *data,
int silent)
{
struct buffer_head *bh;
+ struct buffer_head **map;
struct minix_super_block *ms;
int i, block;
kdev_t dev = s->s_dev;
const char * errmsg;
struct inode *root_inode;
+ /* N.B. These should be compile-time tests */
if (32 != sizeof (struct minix_inode))
panic("bad V1 i-node size");
if (64 != sizeof(struct minix2_inode))
panic("bad V2 i-node size");
+
MOD_INC_USE_COUNT;
lock_super(s);
set_blocksize(dev, BLOCK_SIZE);
- if (!(bh = bread(dev,1,BLOCK_SIZE))) {
- s->s_dev = 0;
- unlock_super(s);
- printk("MINIX-fs: unable to read superblock\n");
- MOD_DEC_USE_COUNT;
- return NULL;
- }
+ if (!(bh = bread(dev,1,BLOCK_SIZE)))
+ goto out_bad_sb;
+
ms = (struct minix_super_block *) bh->b_data;
s->u.minix_sb.s_ms = ms;
s->u.minix_sb.s_sbh = bh;
@@ -192,6 +194,7 @@
s->s_blocksize = 1024;
s->s_blocksize_bits = 10;
s->u.minix_sb.s_ninodes = ms->s_ninodes;
+ s->u.minix_sb.s_nzones = ms->s_nzones;
s->u.minix_sb.s_imap_blocks = ms->s_imap_blocks;
s->u.minix_sb.s_zmap_blocks = ms->s_zmap_blocks;
s->u.minix_sb.s_firstdatazone = ms->s_firstdatazone;
@@ -200,103 +203,74 @@
s->s_magic = ms->s_magic;
if (s->s_magic == MINIX_SUPER_MAGIC) {
s->u.minix_sb.s_version = MINIX_V1;
- s->u.minix_sb.s_nzones = ms->s_nzones;
s->u.minix_sb.s_dirsize = 16;
s->u.minix_sb.s_namelen = 14;
} else if (s->s_magic == MINIX_SUPER_MAGIC2) {
s->u.minix_sb.s_version = MINIX_V1;
- s->u.minix_sb.s_nzones = ms->s_nzones;
s->u.minix_sb.s_dirsize = 32;
s->u.minix_sb.s_namelen = 30;
} else if (s->s_magic == MINIX2_SUPER_MAGIC) {
s->u.minix_sb.s_version = MINIX_V2;
- s->u.minix_sb.s_nzones = ms->s_zones;
s->u.minix_sb.s_dirsize = 16;
s->u.minix_sb.s_namelen = 14;
} else if (s->s_magic == MINIX2_SUPER_MAGIC2) {
s->u.minix_sb.s_version = MINIX_V2;
- s->u.minix_sb.s_nzones = ms->s_zones;
s->u.minix_sb.s_dirsize = 32;
s->u.minix_sb.s_namelen = 30;
- } else {
- s->s_dev = 0;
- unlock_super(s);
- brelse(bh);
- if (!silent)
- printk("VFS: Can't find a minix or minix V2 filesystem on dev "
- "%s.\n", kdevname(dev));
- MOD_DEC_USE_COUNT;
- return NULL;
- }
- for (i=0;i < MINIX_I_MAP_SLOTS;i++)
- s->u.minix_sb.s_imap[i] = NULL;
- for (i=0;i < MINIX_Z_MAP_SLOTS;i++)
- s->u.minix_sb.s_zmap[i] = NULL;
- if (s->u.minix_sb.s_zmap_blocks > MINIX_Z_MAP_SLOTS) {
- s->s_dev = 0;
- unlock_super (s);
- brelse (bh);
- if (!silent)
- printk ("MINIX-fs: filesystem too big\n");
- MOD_DEC_USE_COUNT;
- return NULL;
- }
+ } else
+ goto out_no_fs;
+
+ if (s->u.minix_sb.s_zmap_blocks > MINIX_Z_MAP_SLOTS)
+ goto out_too_big;
+ /*
+ * Allocate the buffer map to keep the superblock small.
+ */
+ i = (MINIX_I_MAP_SLOTS + MINIX_Z_MAP_SLOTS) * sizeof(bh);
+ map = kmalloc(i, GFP_KERNEL);
+ if (!map)
+ goto out_no_map;
+ memset(map, 0, i);
+ s->u.minix_sb.s_imap = &map[0];
+ s->u.minix_sb.s_zmap = &map[MINIX_I_MAP_SLOTS];
+
block=2;
- for (i=0 ; i < s->u.minix_sb.s_imap_blocks ; i++)
- if ((s->u.minix_sb.s_imap[i]=bread(dev,block,BLOCK_SIZE)) != NULL)
- block++;
- else
- break;
- for (i=0 ; i < s->u.minix_sb.s_zmap_blocks ; i++)
- if ((s->u.minix_sb.s_zmap[i]=bread(dev,block,BLOCK_SIZE)) != NULL)
- block++;
- else
- break;
- if (block != 2+s->u.minix_sb.s_imap_blocks+s->u.minix_sb.s_zmap_blocks) {
- for(i=0;i<MINIX_I_MAP_SLOTS;i++)
- brelse(s->u.minix_sb.s_imap[i]);
- for(i=0;i<MINIX_Z_MAP_SLOTS;i++)
- brelse(s->u.minix_sb.s_zmap[i]);
- s->s_dev = 0;
- unlock_super(s);
- brelse(bh);
- printk("MINIX-fs: bad superblock or unable to read bitmaps\n");
- MOD_DEC_USE_COUNT;
- return NULL;
+ for (i=0 ; i < s->u.minix_sb.s_imap_blocks ; i++) {
+ if (!(s->u.minix_sb.s_imap[i]=bread(dev,block,BLOCK_SIZE)))
+ goto out_no_bitmap;
+ block++;
+ }
+ for (i=0 ; i < s->u.minix_sb.s_zmap_blocks ; i++) {
+ if (!(s->u.minix_sb.s_zmap[i]=bread(dev,block,BLOCK_SIZE)))
+ goto out_no_bitmap;
+ block++;
}
+ if (block != 2+s->u.minix_sb.s_imap_blocks+s->u.minix_sb.s_zmap_blocks)
+ goto out_no_bitmap;
+
minix_set_bit(0,s->u.minix_sb.s_imap[0]->b_data);
minix_set_bit(0,s->u.minix_sb.s_zmap[0]->b_data);
- unlock_super(s);
/* set up enough so that it can read an inode */
- s->s_dev = dev;
s->s_op = &minix_sops;
- root_inode = iget(s,MINIX_ROOT_INO);
- s->s_root = d_alloc_root(root_inode, NULL);
- if (!s->s_root) {
- s->s_dev = 0;
- brelse(bh);
- if (!silent)
- printk("MINIX-fs: get root inode failed\n");
- MOD_DEC_USE_COUNT;
- return NULL;
- }
-
+ root_inode = iget(s, MINIX_ROOT_INO);
+ if (!root_inode)
+ goto out_no_root;
+ /*
+ * Check the fs before we get the root dentry ...
+ */
errmsg = minix_checkroot(s, root_inode);
- if (errmsg) {
- if (!silent)
- printk("MINIX-fs: %s\n", errmsg);
- d_delete(s->s_root); /* XXX Is this enough? */
- s->s_dev = 0;
- brelse (bh);
- MOD_DEC_USE_COUNT;
- return NULL;
- }
+ if (errmsg)
+ goto out_bad_root;
+
+ s->s_root = d_alloc_root(root_inode, NULL);
+ if (!s->s_root)
+ goto out_iput;
if (!(s->s_flags & MS_RDONLY)) {
ms->s_state &= ~MINIX_VALID_FS;
mark_buffer_dirty(bh, 1);
s->s_dirt = 1;
}
+ unlock_super(s);
if (!(s->u.minix_sb.s_mount_state & MINIX_VALID_FS))
printk ("MINIX-fs: mounting unchecked file system, "
"running fsck is recommended.\n");
@@ -304,6 +278,54 @@
printk ("MINIX-fs: mounting file system with errors, "
"running fsck is recommended.\n");
return s;
+
+out_bad_root:
+ if (!silent)
+ printk("MINIX-fs: %s\n", errmsg);
+out_iput:
+ iput(root_inode);
+ goto out_freemap;
+
+out_no_root:
+ if (!silent)
+ printk("MINIX-fs: get root inode failed\n");
+ goto out_freemap;
+
+out_no_bitmap:
+ printk("MINIX-fs: bad superblock or unable to read bitmaps\n");
+ out_freemap:
+ for(i=0;i<MINIX_I_MAP_SLOTS;i++)
+ brelse(s->u.minix_sb.s_imap[i]);
+ for(i=0;i<MINIX_Z_MAP_SLOTS;i++)
+ brelse(s->u.minix_sb.s_zmap[i]);
+ kfree(s->u.minix_sb.s_imap);
+ goto out_release;
+
+out_no_map:
+ if (!silent)
+ printk ("MINIX-fs: can't allocate map\n");
+ goto out_release;
+
+out_too_big:
+ if (!silent)
+ printk ("MINIX-fs: filesystem too big\n");
+ goto out_release;
+
+out_no_fs:
+ if (!silent)
+ printk("VFS: Can't find a minix or minix V2 filesystem on dev "
+ "%s.\n", kdevname(dev));
+ out_release:
+ brelse(bh);
+ goto out_unlock;
+
+out_bad_sb:
+ printk("MINIX-fs: unable to read superblock\n");
+ out_unlock:
+ s->s_dev = 0;
+ unlock_super(s);
+ MOD_DEC_USE_COUNT;
+ return NULL;
}
int minix_statfs(struct super_block *sb, struct statfs *buf, int bufsiz)
--------------A42F7733758C1F457AED5C4D--