patch-1.3.60 linux/fs/msdos/buffer.c

• Lines: 151
• Date: Thu Jan 1 02:00:00 1970
• Orig file: v1.3.59/linux/fs/msdos/buffer.c
• Orig date: Mon Nov 27 12:48:32 1995

diff -u --recursive --new-file v1.3.59/linux/fs/msdos/buffer.c linux/fs/msdos/buffer.c
@@ -1,150 +0,0 @@
-/*
- * linux/fs/msdos/buffer.c
- *
- *
- */
-
-#include <linux/mm.h>
-#include <linux/malloc.h>
-#include <linux/string.h>
-#include <linux/fs.h>
-#include <linux/msdos_fs.h>
-
-struct buffer_head *msdos_bread (
-	struct super_block *sb,
-	int block)
-{
-	struct buffer_head *ret = NULL;
-	if (sb->s_blocksize == 512){
-		ret = bread (sb->s_dev,block,512);
-	}else{
-		struct buffer_head *real = bread (sb->s_dev,block>>1,1024);
-		if (real != NULL){
-			ret = (struct buffer_head *)kmalloc (sizeof(struct buffer_head)
-				,GFP_KERNEL);
-			if (ret != NULL){
-				/* #Specification: msdos / strategy / special device / dummy blocks
-					Many special device (Scsi optical disk for one) use
-					larger hardware sector size. This allows for higher
-					capacity.
-
-					Most of the time, the MsDOS file system that sit
-					on this device is totally unaligned. It use logically
-					512 bytes sector size, with logical sector starting
-					in the middle of a hardware block. The bad news is
-					that a hardware sector may hold data own by two
-					different files. This means that the hardware sector
-					must be read, patch and written almost all the time.
-
-					Needless to say that it kills write performance
-					on all OS.
-
-					Internally the linux msdos fs is using 512 bytes
-					logical sector. When accessing such a device, we
-					allocate dummy buffer cache blocks, that we stuff
-					with the information of a real one (1k large).
-
-					This strategy is used to hide this difference to
-					the core of the msdos fs. The slowdown is not
-					hidden though!
-				*/
-				/*
-					The memset is there only to catch errors. The msdos
-					fs is only using b_data
-				*/
-				memset (ret,0,sizeof(*ret));
-				ret->b_data = real->b_data;
-				if (block & 1) ret->b_data += 512;
-				ret->b_next = real;
-			}else{
-				brelse (real);
-			}
-		}
-	}
-	return ret;
-}
-struct buffer_head *msdos_getblk (
-	struct super_block *sb,
-	int block)
-{
-	struct buffer_head *ret = NULL;
-	if (sb->s_blocksize == 512){
-		ret = getblk (sb->s_dev,block,512);
-	}else{
-		/* #Specification: msdos / special device / writing
-			A write is always preceded by a read of the complete block
-			(large hardware sector size). This defeat write performance.
-			There is a possibility to optimize this when writing large
-			chunk by making sure we are filling large block. Volunteer ?
-		*/
-		ret = msdos_bread (sb,block);
-	}
-	return ret;
-}
-
-void msdos_brelse (
-	struct super_block *sb,
-	struct buffer_head *bh)
-{
-	if (bh != NULL){
-		if (sb->s_blocksize == 512){
-			brelse (bh);
-		}else{
-			brelse (bh->b_next);
-			/* We can free the dummy because a new one is allocated at
-				each msdos_getblk() and msdos_bread().
-			*/
-			kfree (bh);
-		}
-	}
-}
-	
-void msdos_mark_buffer_dirty (
-	struct super_block *sb,
-	struct buffer_head *bh,
-	int dirty_val)
-{
-	if (sb->s_blocksize != 512){
-		bh = bh->b_next;
-	}
-	mark_buffer_dirty (bh,dirty_val);
-}
-
-void msdos_set_uptodate (
-	struct super_block *sb,
-	struct buffer_head *bh,
-	int val)
-{
-	if (sb->s_blocksize != 512){
-		bh = bh->b_next;
-	}
-	mark_buffer_uptodate(bh, val);
-}
-int msdos_is_uptodate (
-	struct super_block *sb,
-	struct buffer_head *bh)
-{
-	if (sb->s_blocksize != 512){
-		bh = bh->b_next;
-	}
-	return buffer_uptodate(bh);
-}
-
-void msdos_ll_rw_block (
-	struct super_block *sb,
-	int opr,
-	int nbreq,
-	struct buffer_head *bh[32])
-{
-	if (sb->s_blocksize == 512){
-		ll_rw_block(opr,nbreq,bh);
-	}else{
-		struct buffer_head *tmp[32];
-		int i;
-		for (i=0; i<nbreq; i++){
-			tmp[i] = bh[i]->b_next;
-		}
-		ll_rw_block(opr,nbreq,tmp);
-	}
-}
-