patch-2.3.43 linux/fs/bfs/file.c

• Lines: 189
• Date: Thu Feb 10 12:16:58 2000
• Orig file: v2.3.42/linux/fs/bfs/file.c
• Orig date: Fri Jan 7 19:13:22 2000

diff -u --recursive --new-file v2.3.42/linux/fs/bfs/file.c linux/fs/bfs/file.c
@@ -5,68 +5,149 @@
  */
 
 #include <linux/fs.h>
+#include <linux/locks.h>
 #include <linux/bfs_fs.h>
+#include <linux/smp_lock.h>
 #include "bfs_defs.h"
 
 #undef DEBUG
 
 #ifdef DEBUG
-#define DBG(x...)	printk(x)
+#define dprintf(x...)	printf(x)
 #else
-#define DBG(x...)
+#define dprintf(x...)
 #endif
 
-static ssize_t bfs_file_write(struct file * f, const char * buf, size_t count, loff_t *ppos)
-{
-	return generic_file_write(f, buf, count, ppos, block_write_partial_page);
-}
-
 static struct file_operations bfs_file_operations = {
-	llseek:			NULL,
 	read:			generic_file_read,
-	write:			bfs_file_write,
-	readdir:		NULL,
-	poll:			NULL,
-	ioctl:			NULL,
+	write:			generic_file_write,
 	mmap:			generic_file_mmap,
-	open:			NULL,
-	flush:			NULL,
-	release:		NULL,
-	fsync:			NULL,
-	fasync:			NULL,
 };
 
+static int bfs_move_block(unsigned long from, unsigned long to, kdev_t dev)
+{
+	struct buffer_head *bh, *new = NULL;
+
+	bh = bread(dev, from, BFS_BSIZE);
+	if (!bh)
+		return -EIO;
+	new = getblk(dev, to, BFS_BSIZE);
+	memcpy(new->b_data, bh->b_data, bh->b_size);
+	mark_buffer_dirty(new, 1);
+	bforget(bh);
+	brelse(new);
+	return 0;
+}
+
+static int bfs_move_blocks(kdev_t dev, unsigned long start, unsigned long end, 
+				unsigned long where)
+{
+	unsigned long i;
+
+	dprintf("%08lx-%08lx->%08lx\n", start, end, where);
+	for (i = start; i <= end; i++)
+		if(bfs_move_block(i, where + i, dev)) {
+			dprintf("failed to move block %08lx -> %08lx\n", i, where + i);
+			return -EIO;
+		}
+	return 0;
+}
+
 static int bfs_get_block(struct inode * inode, long block, 
 	struct buffer_head * bh_result, int create)
 {
-	long phys = inode->iu_sblock + block;
-	if (!create || phys <= inode->iu_eblock) {
+	long phys, next_free_block;
+	int err;
+	struct super_block *s = inode->i_sb;
+
+	if (block < 0 || block > s->su_blocks)
+		return -EIO;
+
+	phys = inode->iu_sblock + block;
+	if (!create) {
+		if (phys <= inode->iu_eblock) {
+			dprintf("c=%d, b=%08lx, phys=%08lx (granted)\n", create, block, phys);
+			bh_result->b_dev = inode->i_dev;
+			bh_result->b_blocknr = phys;
+			bh_result->b_state |= (1UL << BH_Mapped);
+		}
+		return 0;
+	}
+
+	/* if the file is not empty and the requested block is within the range
+	   of blocks allocated for this file, we can grant it */
+	if (inode->i_size && phys <= inode->iu_eblock) {
+		dprintf("c=%d, b=%08lx, phys=%08lx (interim block granted)\n", create, block, phys);
 		bh_result->b_dev = inode->i_dev;
 		bh_result->b_blocknr = phys;
 		bh_result->b_state |= (1UL << BH_Mapped);
 		return 0;
-	} 
-	/* no support for file migration, working on it */
-	return -EIO;
+	}
+
+	/* the rest has to be protected against itself */
+	lock_kernel();
+
+	/* if the last data block for this file is the last allocated block, we can
+	   extend the file trivially, without moving it anywhere */
+	if (inode->iu_eblock == s->su_lf_eblk) {
+		dprintf("c=%d, b=%08lx, phys=%08lx (simple extension)\n", create, block, phys);
+		bh_result->b_dev = inode->i_dev;
+		bh_result->b_blocknr = phys;
+		bh_result->b_state |= (1UL << BH_Mapped);
+		s->su_lf_eblk = inode->iu_eblock = inode->iu_sblock + block;
+		mark_inode_dirty(inode);
+		mark_buffer_dirty(s->su_sbh, 1);
+		err = 0;
+		goto out;
+	}
+
+	/* Ok, we have to move this entire file to the next free block */
+	next_free_block = s->su_lf_eblk + 1;
+	if (inode->iu_sblock) { /* if data starts on block 0 then there is no data */
+		err = bfs_move_blocks(inode->i_dev, inode->iu_sblock, inode->iu_eblock, next_free_block);
+		if (err) {
+			dprintf("failed to move ino=%08lx -> possible fs corruption\n", inode->i_ino);
+			goto out;
+		}
+	} else
+		err = 0;
+
+	inode->iu_sblock = next_free_block;
+	s->su_lf_eblk = inode->iu_eblock = next_free_block + block;
+	mark_inode_dirty(inode);
+	mark_buffer_dirty(s->su_sbh, 1);
+	bh_result->b_dev = inode->i_dev;
+	bh_result->b_blocknr = inode->iu_sblock + block;
+	bh_result->b_state |= (1UL << BH_Mapped);
+out:
+	unlock_kernel();
+	return err;
+}
+
+static int bfs_writepage(struct dentry *dentry, struct page *page)
+{
+	return block_write_full_page(page,bfs_get_block);
 }
+static int bfs_readpage(struct dentry *dentry, struct page *page)
+{
+	return block_read_full_page(page,bfs_get_block);
+}
+static int bfs_prepare_write(struct page *page, unsigned from, unsigned to)
+{
+	return block_prepare_write(page,from,to,bfs_get_block);
+}
+static int bfs_bmap(struct address_space *mapping, long block)
+{
+	return generic_block_bmap(mapping,block,bfs_get_block);
+}
+struct address_space_operations bfs_aops = {
+	readpage: bfs_readpage,
+	writepage: bfs_writepage,
+	prepare_write: bfs_prepare_write,
+	commit_write: generic_commit_write,
+	bmap: bfs_bmap
+};
 
 struct inode_operations bfs_file_inops = {
 	default_file_ops:	&bfs_file_operations,
-	create:			NULL,
-	lookup:			NULL,
-	link:			NULL,
-	unlink:			NULL,
-	symlink:		NULL,
-	mkdir:			NULL,
-	rmdir:			NULL,
-	mknod:			NULL,
-	rename:			NULL,
-	readlink:		NULL,
-	follow_link:		NULL,
-	get_block:		bfs_get_block,	
-	readpage:		block_read_full_page,
-	writepage:		block_write_full_page,
-	truncate:		NULL,
-	permission:		NULL,
-	revalidate:		NULL
 };