freevxfs: handle big endian HP-UX file systems

To support VxFS filesystems from HP-UX on x86 systems we need to
implement byte swapping, and to keep support for Unixware filesystems
it needs to be the complicated dual-endian kind ala sysvfs.

To do this properly we have to split the on disk and in-core inode
so that we can keep the in-core one in native endianness.  All other
structures are byteswapped on demand.

Signed-off-by: Krzysztof Błaszkowski <kb@sysmikro.com.pl>
[hch: make spare happy]
Signed-off-by: Christoph Hellwig <hch@lst.de>

1 files changed, 73 insertions, 28 deletions

diff --git a/fs/freevxfs/vxfs_super.c b/fs/freevxfs/vxfs_super.c
index 7ca8c75d50d3..6124091b4fdb 100644
--- a/fs/freevxfs/vxfs_super.c
+++ b/fs/freevxfs/vxfs_super.c
@@ -109,14 +109,15 @@ static int
 vxfs_statfs(struct dentry *dentry, struct kstatfs *bufp)
 {
 	struct vxfs_sb_info		*infp = VXFS_SBI(dentry->d_sb);
+	struct vxfs_sb *raw_sb = infp->vsi_raw;
 
 	bufp->f_type = VXFS_SUPER_MAGIC;
 	bufp->f_bsize = dentry->d_sb->s_blocksize;
-	bufp->f_blocks = infp->vsi_raw->vs_dsize;
-	bufp->f_bfree = infp->vsi_raw->vs_free;
+	bufp->f_blocks = fs32_to_cpu(infp, raw_sb->vs_dsize);
+	bufp->f_bfree = fs32_to_cpu(infp, raw_sb->vs_free);
 	bufp->f_bavail = 0;
 	bufp->f_files = 0;
-	bufp->f_ffree = infp->vsi_raw->vs_ifree;
+	bufp->f_ffree = fs32_to_cpu(infp, raw_sb->vs_ifree);
 	bufp->f_namelen = VXFS_NAMELEN;
 
 	return 0;
@@ -129,6 +130,50 @@ static int vxfs_remount(struct super_block *sb, int *flags, char *data)
 	return 0;
 }
 
+
+static int vxfs_try_sb_magic(struct super_block *sbp, int silent,
+		unsigned blk, __fs32 magic)
+{
+	struct buffer_head *bp;
+	struct vxfs_sb *rsbp;
+	struct vxfs_sb_info *infp = VXFS_SBI(sbp);
+	int rc = -ENOMEM;
+
+	bp = sb_bread(sbp, blk);
+	do {
+		if (!bp || !buffer_mapped(bp)) {
+			if (!silent) {
+				printk(KERN_WARNING
+					"vxfs: unable to read disk superblock at %u\n",
+					blk);
+			}
+			break;
+		}
+
+		rc = -EINVAL;
+		rsbp = (struct vxfs_sb *)bp->b_data;
+		if (rsbp->vs_magic != magic) {
+			if (!silent)
+				printk(KERN_NOTICE
+					"vxfs: WRONG superblock magic %08x at %u\n",
+					rsbp->vs_magic, blk);
+			break;
+		}
+
+		rc = 0;
+		infp->vsi_raw = rsbp;
+		infp->vsi_bp = bp;
+	} while (0);
+
+	if (rc) {
+		infp->vsi_raw = NULL;
+		infp->vsi_bp = NULL;
+		brelse(bp);
+	}
+
+	return rc;
+}
+
 /**
  * vxfs_read_super - read superblock into memory and initialize filesystem
  * @sbp:		VFS superblock (to fill)
@@ -149,10 +194,10 @@ static int vxfs_fill_super(struct super_block *sbp, void *dp, int silent)
 {
 	struct vxfs_sb_info	*infp;
 	struct vxfs_sb		*rsbp;
-	struct buffer_head	*bp = NULL;
 	u_long			bsize;
 	struct inode *root;
 	int ret = -EINVAL;
+	u32 j;
 
 	sbp->s_flags |= MS_RDONLY;
 
@@ -168,42 +213,42 @@ static int vxfs_fill_super(struct super_block *sbp, void *dp, int silent)
 		goto out;
 	}
 
-	bp = sb_bread(sbp, 1);
-	if (!bp || !buffer_mapped(bp)) {
-		if (!silent) {
-			printk(KERN_WARNING
-				"vxfs: unable to read disk superblock\n");
-		}
-		goto out;
-	}
+	sbp->s_fs_info = infp;
 
-	rsbp = (struct vxfs_sb *)bp->b_data;
-	if (rsbp->vs_magic != VXFS_SUPER_MAGIC) {
+	if (!vxfs_try_sb_magic(sbp, silent, 1,
+			(__force __fs32)cpu_to_le32(VXFS_SUPER_MAGIC))) {
+		/* Unixware, x86 */
+		infp->byte_order = VXFS_BO_LE;
+	} else if (!vxfs_try_sb_magic(sbp, silent, 8,
+			(__force __fs32)cpu_to_be32(VXFS_SUPER_MAGIC))) {
+		/* HP-UX, parisc */
+		infp->byte_order = VXFS_BO_BE;
+	} else {
 		if (!silent)
-			printk(KERN_NOTICE "vxfs: WRONG superblock magic\n");
+			printk(KERN_NOTICE "vxfs: can't find superblock.\n");
 		goto out;
 	}
 
-	if ((rsbp->vs_version < 2 || rsbp->vs_version > 4) && !silent) {
-		printk(KERN_NOTICE "vxfs: unsupported VxFS version (%d)\n",
-		       rsbp->vs_version);
+	rsbp = infp->vsi_raw;
+	j = fs32_to_cpu(infp, rsbp->vs_version);
+	if ((j < 2 || j > 4) && !silent) {
+		printk(KERN_NOTICE "vxfs: unsupported VxFS version (%d)\n", j);
 		goto out;
 	}
 
 #ifdef DIAGNOSTIC
-	printk(KERN_DEBUG "vxfs: supported VxFS version (%d)\n", rsbp->vs_version);
-	printk(KERN_DEBUG "vxfs: blocksize: %d\n", rsbp->vs_bsize);
+	printk(KERN_DEBUG "vxfs: supported VxFS version (%d)\n", j);
+	printk(KERN_DEBUG "vxfs: blocksize: %d\n",
+		fs32_to_cpu(infp, rsbp->vs_bsize));
 #endif
 
-	sbp->s_magic = rsbp->vs_magic;
-	sbp->s_fs_info = infp;
+	sbp->s_magic = fs32_to_cpu(infp, rsbp->vs_magic);
 
-	infp->vsi_raw = rsbp;
-	infp->vsi_bp = bp;
-	infp->vsi_oltext = rsbp->vs_oltext[0];
-	infp->vsi_oltsize = rsbp->vs_oltsize;
+	infp->vsi_oltext = fs32_to_cpu(infp, rsbp->vs_oltext[0]);
+	infp->vsi_oltsize = fs32_to_cpu(infp, rsbp->vs_oltsize);
 
-	if (!sb_set_blocksize(sbp, rsbp->vs_bsize)) {
+	j = fs32_to_cpu(infp, rsbp->vs_bsize);
+	if (!sb_set_blocksize(sbp, j)) {
 		printk(KERN_WARNING "vxfs: unable to set final block size\n");
 		goto out;
 	}
@@ -237,7 +282,7 @@ out_free_ilist:
 	vxfs_put_fake_inode(infp->vsi_ilist);
 	vxfs_put_fake_inode(infp->vsi_stilist);
 out:
-	brelse(bp);
+	brelse(infp->vsi_bp);
 	kfree(infp);
 	return ret;
 }