patch-1.3.94 linux/fs/ufs/ufs_file.c

• Lines: 145
• Date: Mon Apr 22 10:59:39 1996
• Orig file: v1.3.93/linux/fs/ufs/ufs_file.c
• Orig date: Thu Jan 1 02:00:00 1970

diff -u --recursive --new-file v1.3.93/linux/fs/ufs/ufs_file.c linux/fs/ufs/ufs_file.c
@@ -0,0 +1,144 @@
+/*
+ *  linux/fs/ufs/ufs_file.c
+ *
+ * Copyright (C) 1996
+ * Adrian Rodriguez (adrian@franklins-tower.rutgers.edu)
+ * Laboratory for Computer Science Research Computing Facility
+ * Rutgers, The State University of New Jersey
+ *
+ * $Id: ufs_file.c,v 1.1 1996/04/21 14:41:08 davem Exp $
+ *
+ */
+
+#include <linux/fs.h>
+
+/*
+ * Return values:
+ *   0:  bmap failed
+ *  nonzero: absolute "block" number
+ */
+int ufs_bmap (struct inode * inode, int block)
+{
+	unsigned long int fsblkno, phys_block, lfsblkno;
+	struct buffer_head * bh;
+
+	/*
+	 * Note that contrary to what the BSD source calls these things,
+	 * blkno and lblkno are *frags* (1024), not UFS blocks (8192).
+	 * XXX - maybe I'm wrong, and ui_blocks is really 512-blocks...
+	 */
+
+	/*
+	 * Ok, I think I figured out what is going on.  ui_blocks is the
+	 * number of 512-byte blocks that are allocated to the file.  The
+	 * elements in ui_db[UFS_NDADDR] are pointers to 1024-byte aligned
+	 * 8192 byte objects.  The entire 8192 bytes (16 512-blocks) may
+	 * not be allocated to the file in question - use ui_blocks to see
+	 * how many of the blocks are allocated.  Also, use ui_size to see
+	 * what fraction of the last block is allocated to the file, and
+	 * what fraction is unused.  I have not yet seen a file with a
+	 * hole in it, but I'd guess that a hole must be at least 8192
+	 * bytes of zeros, and it's represented by a zero in ui_db[X].
+	 *
+	 * Yes, this means that there is more than one way to name a given
+	 * 512-byte block on the disk. Because of the 1024-byte alignment
+	 * of 8192-byte filesystem blocks, a given 512-byte disk block
+	 * could be referred to in eight different ways.
+	 */
+
+	/*
+	 * block is the logical 1024-block in the file
+	 * lfsblkno is the logical 8192-block in the file
+	 * fsblkno is the physical 8192-block
+	 * phys_block is the 1024-block
+	 */
+	lfsblkno = block>>3;
+
+	if (block < UFS_NDADDR) {
+	        /* It's a direct block */
+	        fsblkno = inode->u.ufs_i.ui_db[lfsblkno]; /* XXX */
+#if 0
+	        phys_block = ufs_cgdmin(inode->i_sb, ufs_ino2cg(inode)) +
+	                blkno%(inode->i_sb->u.ufs_sb.s_fpg);
+#endif
+	        phys_block = fsblkno + ((block & 0x7)<<10); /* XXX */
+	        if (inode->i_sb->u.ufs_sb.s_flags & UFS_DEBUG) {
+	                printk("ufs_bmap: mapped ino %lu  logical %u to %lu (phys %lu)\n",
+	                       inode->i_ino, block, fsblkno, phys_block);
+	        }
+	        return(phys_block);
+	} else {
+	        /* Need to use indirect blocks */
+	        /* XXX - bmap through indirect blocks not implemented */
+	        block -= UFS_NDADDR;
+	        if (block < (inode->i_sb->s_blocksize/sizeof(__u32))) {
+	                bh = bread(inode->i_dev, inode->u.ufs_i.ui_ib[0],
+	                           BLOCK_SIZE);
+	                if (bh == NULL) {
+	                        printk("ufs_bmap: can't map block %lu, ino %lu\n",
+	                               block + UFS_NDADDR, inode->i_ino);
+	                        return(0);
+	                }
+	                phys_block = ((__u32 *)bh->b_data)[block];
+	                brelse(bh);
+	                printk("ufs_bmap: imap ino %lu block %lu phys %lu\n",
+	                       inode->i_ino, block + UFS_NDADDR, phys_block);
+	                return(phys_block);
+	        } else {
+	                printk("ufs_bmap: ino %lu: indirect blocks not implemented\n",
+	                       inode->i_ino);
+	                return(0);
+	        }
+	}
+
+	return(0);
+}
+
+
+static struct file_operations ufs_file_operations = {
+	NULL,			/* lseek */
+	&generic_file_read,	/* read */
+	NULL,			/* write */
+	NULL,			/* readdir */
+	NULL,			/* select */
+	NULL,			/* ioctl */
+	&generic_file_mmap,	/* mmap */
+	NULL,			/* open */
+	NULL,			/* release */
+	&file_fsync,		/* fsync */  /* XXX - is this ok? */
+	NULL,			/* fasync */
+	NULL,			/* check_media_change */
+	NULL,			/* revalidate */
+};
+
+struct inode_operations ufs_file_inode_operations = {
+	&ufs_file_operations,	/* default directory file operations */
+	NULL,			/* create */
+	NULL,			/* lookup */
+	NULL,			/* link */
+	NULL,			/* unlink */
+	NULL,			/* symlink */
+	NULL,			/* mkdir */
+	NULL,			/* rmdir */
+	NULL,			/* mknod */
+	NULL,			/* rename */
+	NULL,			/* readlink */
+	NULL,			/* follow_link */
+	&generic_readpage,	/* readpage */
+	NULL,			/* writepage */
+	&ufs_bmap,		/* bmap */
+	NULL,			/* truncate */
+	NULL,			/* permission */
+	NULL,			/* smap */
+};
+
+
+/*
+ * Local Variables: ***
+ * c-indent-level: 8 ***
+ * c-continued-statement-offset: 8 ***
+ * c-brace-offset: -8 ***
+ * c-argdecl-indent: 0 ***
+ * c-label-offset: -8 ***
+ * End: ***
+ */