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1628 |
jcastillo |
/*
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* linux/fs/ufs/ufs_file.c
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*
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* Copyright (C) 1996
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* Adrian Rodriguez (adrian@franklins-tower.rutgers.edu)
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* Laboratory for Computer Science Research Computing Facility
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* Rutgers, The State University of New Jersey
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*
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* $Id: ufs_file.c,v 1.1 2005-12-20 10:26:35 jcastillo Exp $
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*
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*/
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#include <linux/fs.h>
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/*
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* Return values:
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* 0: bmap failed
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* nonzero: absolute "block" number
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*/
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int ufs_bmap (struct inode * inode, int block)
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{
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unsigned long int fsblkno, phys_block, lfsblkno;
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struct buffer_head * bh;
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/*
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* Note that contrary to what the BSD source calls these things,
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* blkno and lblkno are *frags* (1024), not UFS blocks (8192).
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* XXX - maybe I'm wrong, and ui_blocks is really 512-blocks...
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*/
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/*
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* Ok, I think I figured out what is going on. ui_blocks is the
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* number of 512-byte blocks that are allocated to the file. The
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* elements in ui_db[UFS_NDADDR] are pointers to 1024-byte aligned
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* 8192 byte objects. The entire 8192 bytes (16 512-blocks) may
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* not be allocated to the file in question - use ui_blocks to see
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* how many of the blocks are allocated. Also, use ui_size to see
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* what fraction of the last block is allocated to the file, and
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* what fraction is unused. I have not yet seen a file with a
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* hole in it, but I'd guess that a hole must be at least 8192
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* bytes of zeros, and it's represented by a zero in ui_db[X].
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*
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* Yes, this means that there is more than one way to name a given
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* 512-byte block on the disk. Because of the 1024-byte alignment
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* of 8192-byte filesystem blocks, a given 512-byte disk block
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* could be referred to in eight different ways.
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*/
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/*
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* block is the logical 1024-block in the file
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* lfsblkno is the logical 8192-block in the file
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* fsblkno is the physical 8192-block
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* phys_block is the 1024-block
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*/
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lfsblkno = block>>3;
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if (block < UFS_NDADDR) {
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/* It's a direct block */
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fsblkno = inode->u.ufs_i.ui_db[lfsblkno]; /* XXX */
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#if 0
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phys_block = ufs_cgdmin(inode->i_sb, ufs_ino2cg(inode)) +
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blkno%(inode->i_sb->u.ufs_sb.s_fpg);
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#endif
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phys_block = fsblkno + ((block & 0x7)<<10); /* XXX */
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if (inode->i_sb->u.ufs_sb.s_flags & UFS_DEBUG) {
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printk("ufs_bmap: mapped ino %lu logical %u to %lu (phys %lu)\n",
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inode->i_ino, block, fsblkno, phys_block);
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}
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return(phys_block);
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} else {
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/* Need to use indirect blocks */
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/* XXX - bmap through indirect blocks not implemented */
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block -= UFS_NDADDR;
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if (block < (inode->i_sb->s_blocksize/sizeof(__u32))) {
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bh = bread(inode->i_dev, inode->u.ufs_i.ui_ib[0],
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BLOCK_SIZE);
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if (bh == NULL) {
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printk("ufs_bmap: can't map block %u, ino %lu\n",
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block + UFS_NDADDR, inode->i_ino);
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return(0);
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}
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phys_block = ((__u32 *)bh->b_data)[block];
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brelse(bh);
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printk("ufs_bmap: imap ino %lu block %u phys %lu\n",
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inode->i_ino, block + UFS_NDADDR, phys_block);
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return(phys_block);
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} else {
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printk("ufs_bmap: ino %lu: indirect blocks not implemented\n",
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inode->i_ino);
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return(0);
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}
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}
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return(0);
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}
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static struct file_operations ufs_file_operations = {
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NULL, /* lseek */
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generic_file_read, /* read */
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NULL, /* write */
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NULL, /* readdir */
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NULL, /* select */
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NULL, /* ioctl */
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generic_file_mmap, /* mmap */
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NULL, /* open */
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NULL, /* release */
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file_fsync, /* fsync */
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NULL, /* fasync */
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NULL, /* check_media_change */
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NULL, /* revalidate */
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};
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struct inode_operations ufs_file_inode_operations = {
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&ufs_file_operations, /* default directory file operations */
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NULL, /* create */
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NULL, /* lookup */
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NULL, /* link */
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NULL, /* unlink */
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NULL, /* symlink */
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NULL, /* mkdir */
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NULL, /* rmdir */
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NULL, /* mknod */
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NULL, /* rename */
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NULL, /* readlink */
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NULL, /* follow_link */
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generic_readpage, /* readpage */
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NULL, /* writepage */
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ufs_bmap, /* bmap */
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NULL, /* truncate */
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NULL, /* permission */
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NULL, /* smap */
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};
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/*
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* Local Variables: ***
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* c-indent-level: 8 ***
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* c-continued-statement-offset: 8 ***
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* c-brace-offset: -8 ***
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* c-argdecl-indent: 0 ***
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* c-label-offset: -8 ***
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* End: ***
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*/
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