patch-2.3.2 linux/fs/efs/inode.c

• Lines: 302
• Date: Thu May 13 23:50:15 1999
• Orig file: v2.3.1/linux/fs/efs/inode.c
• Orig date: Wed Dec 31 16:00:00 1969

diff -u --recursive --new-file v2.3.1/linux/fs/efs/inode.c linux/fs/efs/inode.c
@@ -0,0 +1,301 @@
+/*
+ * inode.c
+ *
+ * Copyright (c) 1999 Al Smith
+ *
+ * Portions derived from work (c) 1995,1996 Christian Vogelgsang,
+ *              and from work (c) 1998 Mike Shaver.
+ */
+
+#include <linux/efs_fs.h>
+#include <linux/efs_fs_sb.h>
+
+static inline void extent_copy(efs_extent *src, efs_extent *dst) {
+	/*
+	 * this is slightly evil. it doesn't just copy
+	 * efs_extent from src to dst, it also mangles
+	 * the bits so that dst ends up in cpu byte-order.
+	 */
+
+	dst->cooked.ex_magic  =  (unsigned int) src->raw[0];
+	dst->cooked.ex_bn     = ((unsigned int) src->raw[1] << 16) |
+				((unsigned int) src->raw[2] <<  8) |
+				((unsigned int) src->raw[3] <<  0);
+	dst->cooked.ex_length =  (unsigned int) src->raw[4];
+	dst->cooked.ex_offset = ((unsigned int) src->raw[5] << 16) |
+				((unsigned int) src->raw[6] <<  8) |
+				((unsigned int) src->raw[7] <<  0);
+	return;
+}
+
+void efs_read_inode(struct inode *inode) {
+	int i, inode_index;
+	dev_t device;
+	struct buffer_head *bh;
+	struct efs_sb_info    *sb = SUPER_INFO(inode->i_sb);
+	struct efs_inode_info *in = INODE_INFO(inode);
+	efs_block_t block, offset;
+	struct efs_dinode *efs_inode;
+  
+	/*
+	** EFS layout:
+	**
+	** |   cylinder group    |   cylinder group    |   cylinder group ..etc
+	** |inodes|data          |inodes|data          |inodes|data       ..etc
+	**
+	** work out the inode block index, (considering initially that the
+	** inodes are stored as consecutive blocks). then work out the block
+	** number of that inode given the above layout, and finally the
+	** offset of the inode within that block.
+	*/
+
+	inode_index = inode->i_ino /
+		(EFS_BLOCKSIZE / sizeof(struct efs_dinode));
+
+	block = sb->fs_start + sb->first_block + 
+		(sb->group_size * (inode_index / sb->inode_blocks)) +
+		(inode_index % sb->inode_blocks);
+
+	offset = (inode->i_ino %
+			(EFS_BLOCKSIZE / sizeof(struct efs_dinode))) *
+		sizeof(struct efs_dinode);
+
+	bh = bread(inode->i_dev, block, EFS_BLOCKSIZE);
+	if (!bh) {
+		printk(KERN_WARNING "EFS: bread() failed at block %d\n", block);
+		goto read_inode_error;
+	}
+
+	efs_inode = (struct efs_dinode *) (bh->b_data + offset);
+    
+	inode->i_mode  = be16_to_cpu(efs_inode->di_mode);
+	inode->i_nlink = be16_to_cpu(efs_inode->di_nlink);
+	inode->i_uid   = be16_to_cpu(efs_inode->di_uid);
+	inode->i_gid   = be16_to_cpu(efs_inode->di_gid);
+	inode->i_size  = be32_to_cpu(efs_inode->di_size);
+	inode->i_atime = be32_to_cpu(efs_inode->di_atime);
+	inode->i_mtime = be32_to_cpu(efs_inode->di_mtime);
+	inode->i_ctime = be32_to_cpu(efs_inode->di_ctime);
+
+	/* this is the number of blocks in the file */
+	if (inode->i_size == 0) {
+		inode->i_blocks = 0;
+	} else {
+		inode->i_blocks = ((inode->i_size - 1) >> EFS_BLOCKSIZE_BITS) + 1;
+	}
+
+	/*
+	 * BUG: irix dev_t is 32-bits. linux dev_t is only 16-bits.
+	 *
+	 * apparently linux will change to 32-bit dev_t sometime during
+	 * linux 2.3.
+	 *
+	 * as is, this code maps devices that can't be represented in
+	 * 16-bits (ie major > 255 or minor > 255) to major = minor = 255.
+	 *
+	 * during 2.3 when 32-bit dev_t become available, we should test
+	 * to see whether odev contains 65535. if this is the case then we
+	 * should then do device = be32_to_cpu(efs_inode->di_u.di_dev.ndev).
+	 */
+    	device = be16_to_cpu(efs_inode->di_u.di_dev.odev);
+
+	/* get the number of extents for this object */
+	in->numextents = be16_to_cpu(efs_inode->di_numextents);
+	in->lastextent = 0;
+
+	/* copy the extents contained within the inode to memory */
+	for(i = 0; i < EFS_DIRECTEXTENTS; i++) {
+		extent_copy(&(efs_inode->di_u.di_extents[i]), &(in->extents[i]));
+		if (i < in->numextents && in->extents[i].cooked.ex_magic != 0) {
+			printk(KERN_WARNING "EFS: extent %d has bad magic number in inode %lu\n", i, inode->i_ino);
+			brelse(bh);
+			goto read_inode_error;
+		}
+	}
+
+	brelse(bh);
+   
+#ifdef DEBUG
+	printk(KERN_DEBUG "EFS: read_inode(): inode %lu, extents %d, mode %o\n",
+		inode->i_ino, in->numextents, inode->i_mode);
+#endif
+
+	switch (inode->i_mode & S_IFMT) {
+		case S_IFDIR: 
+			inode->i_op = &efs_dir_inode_operations; 
+			break;
+		case S_IFREG:
+			inode->i_op = &efs_file_inode_operations;
+			break;
+		case S_IFLNK:
+			inode->i_op = &efs_symlink_inode_operations;
+			break;
+		case S_IFCHR:
+			inode->i_rdev = device;
+			inode->i_op = &chrdev_inode_operations; 
+			break;
+		case S_IFBLK:
+			inode->i_rdev = device;
+			inode->i_op = &blkdev_inode_operations; 
+			break;
+		case S_IFIFO:
+			init_fifo(inode);
+			break;    
+		default:
+			printk(KERN_WARNING "EFS: unsupported inode mode %o\n", inode->i_mode);
+			goto read_inode_error;
+			break;
+	}
+
+	return;
+        
+read_inode_error:
+	printk(KERN_WARNING "EFS: failed to read inode %lu\n", inode->i_ino);
+	inode->i_mode = S_IFREG;
+	inode->i_atime = 0;
+	inode->i_ctime = 0;
+	inode->i_mtime = 0;
+	inode->i_nlink = 1;
+	inode->i_size = 0;
+	inode->i_blocks = 0;
+	inode->i_uid = 0;
+	inode->i_gid = 0;
+	inode->i_op = NULL;
+
+	return;
+}
+
+static inline efs_block_t
+efs_extent_check(efs_extent *ptr, efs_block_t block, struct efs_sb_info *sb) {
+	efs_block_t start;
+	efs_block_t length;
+	efs_block_t offset;
+
+	/*
+	 * given an extent and a logical block within a file,
+	 * can this block be found within this extent ?
+	 */
+	start  = ptr->cooked.ex_bn;
+	length = ptr->cooked.ex_length;
+	offset = ptr->cooked.ex_offset;
+
+	if ((block >= offset) && (block < offset+length)) {
+		return(sb->fs_start + start + block - offset);
+	} else {
+		return 0;
+	}
+}
+
+efs_block_t efs_map_block(struct inode *inode, efs_block_t block) {
+	struct efs_sb_info    *sb = SUPER_INFO(inode->i_sb);
+	struct efs_inode_info *in = INODE_INFO(inode);
+	struct buffer_head    *bh = NULL;
+
+	int cur, last, first = 1;
+	int ibase, ioffset, dirext, direxts, indext, indexts;
+	efs_block_t iblock, result = 0, lastblock = 0;
+	efs_extent ext, *exts;
+
+	last = in->lastextent;
+
+	if (in->numextents <= EFS_DIRECTEXTENTS) {
+		/* first check the last extent we returned */
+		if ((result = efs_extent_check(&in->extents[last], block, sb)))
+			return result;
+    
+		/* if we only have one extent then nothing can be found */
+		if (in->numextents == 1) {
+			printk(KERN_ERR "EFS: map_block() failed to map (1 extent)\n");
+			return 0;
+		}
+
+		direxts = in->numextents;
+
+		/*
+		 * check the stored extents in the inode
+		 * start with next extent and check forwards
+		 */
+		for(dirext = 1; dirext < direxts; dirext++) {
+			cur = (last + dirext) % in->numextents;
+			if ((result = efs_extent_check(&in->extents[cur], block, sb))) {
+				in->lastextent = cur;
+				return result;
+			}
+		}
+
+		printk(KERN_ERR "EFS: map_block() failed to map block %u (dir)\n", block);
+		return 0;
+	}
+
+#ifdef DEBUG
+	printk(KERN_DEBUG "EFS: map_block(): indirect search for logical block %u\n", block);
+#endif
+	direxts = in->extents[0].cooked.ex_offset;
+	indexts = in->numextents;
+
+	for(indext = 0; indext < indexts; indext++) {
+		cur = (last + indext) % indexts;
+
+		/*
+		 * work out which direct extent contains `cur'.
+		 *
+		 * also compute ibase: i.e. the number of the first
+		 * indirect extent contained within direct extent `cur'.
+		 *
+		 */
+		ibase = 0;
+		for(dirext = 0; cur < ibase && dirext < direxts; dirext++) {
+			ibase += in->extents[dirext].cooked.ex_length *
+				(EFS_BLOCKSIZE / sizeof(efs_extent));
+		}
+
+		if (dirext == direxts) {
+			/* should never happen */
+			printk(KERN_ERR "EFS: couldn't find direct extent for indirect extent %d (block %u)\n", cur, block);
+			if (bh) brelse(bh);
+			return 0;
+		}
+		
+		/* work out block number and offset of this indirect extent */
+		iblock = sb->fs_start + in->extents[dirext].cooked.ex_bn +
+			(cur - ibase) /
+			(EFS_BLOCKSIZE / sizeof(efs_extent));
+		ioffset = (cur - ibase) %
+			(EFS_BLOCKSIZE / sizeof(efs_extent));
+
+		if (first || lastblock != iblock) {
+			if (bh) brelse(bh);
+
+			bh = bread(inode->i_dev, iblock, EFS_BLOCKSIZE);
+			if (!bh) {
+				printk(KERN_ERR "EFS: bread() failed at block %d\n", iblock);
+				return 0;
+			}
+#ifdef DEBUG
+			printk(KERN_DEBUG "EFS: map_block(): read indirect extent block %d\n", iblock);
+#endif
+			first = 0;
+			lastblock = iblock;
+		}
+
+		exts = (efs_extent *) bh->b_data;
+
+		extent_copy(&(exts[ioffset]), &ext);
+
+		if (ext.cooked.ex_magic != 0) {
+			printk(KERN_ERR "EFS: extent %d has bad magic number in block %d\n", cur, iblock);
+			if (bh) brelse(bh);
+			return 0;
+		}
+
+		if ((result = efs_extent_check(&ext, block, sb))) {
+			if (bh) brelse(bh);
+			in->lastextent = cur;
+			return result;
+		}
+	}
+	if (bh) brelse(bh);
+	printk(KERN_ERR "EFS: map_block() failed to map block %u (indir)\n", block);
+	return 0;
+}  
+