1 files changed, 193 insertions, 0 deletions
diff --git a/fs/isofs/export.c b/fs/isofs/export.c
new file mode 100644
index 000000000..35768a63f
--- /dev/null
+++ b/fs/isofs/export.c
@@ -0,0 +1,193 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * fs/isofs/export.c
+ *
+ *  (C) 2004  Paul Serice - The new inode scheme requires switching
+ *                          from iget() to iget5_locked() which means
+ *                          the NFS export operations have to be hand
+ *                          coded because the default routines rely on
+ *                          iget().
+ *
+ * The following files are helpful:
+ *
+ *     Documentation/filesystems/nfs/exporting.rst
+ *     fs/exportfs/expfs.c.
+ */
+
+#include "isofs.h"
+
+static struct dentry *
+isofs_export_iget(struct super_block *sb,
+		  unsigned long block,
+		  unsigned long offset,
+		  __u32 generation)
+{
+	struct inode *inode;
+
+	if (block == 0)
+		return ERR_PTR(-ESTALE);
+	inode = isofs_iget(sb, block, offset);
+	if (IS_ERR(inode))
+		return ERR_CAST(inode);
+	if (generation && inode->i_generation != generation) {
+		iput(inode);
+		return ERR_PTR(-ESTALE);
+	}
+	return d_obtain_alias(inode);
+}
+
+/* This function is surprisingly simple.  The trick is understanding
+ * that "child" is always a directory. So, to find its parent, you
+ * simply need to find its ".." entry, normalize its block and offset,
+ * and return the underlying inode.  See the comments for
+ * isofs_normalize_block_and_offset(). */
+static struct dentry *isofs_export_get_parent(struct dentry *child)
+{
+	unsigned long parent_block = 0;
+	unsigned long parent_offset = 0;
+	struct inode *child_inode = d_inode(child);
+	struct iso_inode_info *e_child_inode = ISOFS_I(child_inode);
+	struct iso_directory_record *de = NULL;
+	struct buffer_head * bh = NULL;
+	struct dentry *rv = NULL;
+
+	/* "child" must always be a directory. */
+	if (!S_ISDIR(child_inode->i_mode)) {
+		printk(KERN_ERR "isofs: isofs_export_get_parent(): "
+		       "child is not a directory!\n");
+		rv = ERR_PTR(-EACCES);
+		goto out;
+	}
+
+	/* It is an invariant that the directory offset is zero.  If
+	 * it is not zero, it means the directory failed to be
+	 * normalized for some reason. */
+	if (e_child_inode->i_iget5_offset != 0) {
+		printk(KERN_ERR "isofs: isofs_export_get_parent(): "
+		       "child directory not normalized!\n");
+		rv = ERR_PTR(-EACCES);
+		goto out;
+	}
+
+	/* The child inode has been normalized such that its
+	 * i_iget5_block value points to the "." entry.  Fortunately,
+	 * the ".." entry is located in the same block. */
+	parent_block = e_child_inode->i_iget5_block;
+
+	/* Get the block in question. */
+	bh = sb_bread(child_inode->i_sb, parent_block);
+	if (bh == NULL) {
+		rv = ERR_PTR(-EACCES);
+		goto out;
+	}
+
+	/* This is the "." entry. */
+	de = (struct iso_directory_record*)bh->b_data;
+
+	/* The ".." entry is always the second entry. */
+	parent_offset = (unsigned long)isonum_711(de->length);
+	de = (struct iso_directory_record*)(bh->b_data + parent_offset);
+
+	/* Verify it is in fact the ".." entry. */
+	if ((isonum_711(de->name_len) != 1) || (de->name[0] != 1)) {
+		printk(KERN_ERR "isofs: Unable to find the \"..\" "
+		       "directory for NFS.\n");
+		rv = ERR_PTR(-EACCES);
+		goto out;
+	}
+
+	/* Normalize */
+	isofs_normalize_block_and_offset(de, &parent_block, &parent_offset);
+
+	rv = d_obtain_alias(isofs_iget(child_inode->i_sb, parent_block,
+				     parent_offset));
+ out:
+	if (bh)
+		brelse(bh);
+	return rv;
+}
+
+static int
+isofs_export_encode_fh(struct inode *inode,
+		       __u32 *fh32,
+		       int *max_len,
+		       struct inode *parent)
+{
+	struct iso_inode_info * ei = ISOFS_I(inode);
+	int len = *max_len;
+	int type = 1;
+	__u16 *fh16 = (__u16*)fh32;
+
+	/*
+	 * WARNING: max_len is 5 for NFSv2.  Because of this
+	 * limitation, we use the lower 16 bits of fh32[1] to hold the
+	 * offset of the inode and the upper 16 bits of fh32[1] to
+	 * hold the offset of the parent.
+	 */
+	if (parent && (len < 5)) {
+		*max_len = 5;
+		return FILEID_INVALID;
+	} else if (len < 3) {
+		*max_len = 3;
+		return FILEID_INVALID;
+	}
+
+	len = 3;
+	fh32[0] = ei->i_iget5_block;
+ 	fh16[2] = (__u16)ei->i_iget5_offset;  /* fh16 [sic] */
+	fh16[3] = 0;  /* avoid leaking uninitialized data */
+	fh32[2] = inode->i_generation;
+	if (parent) {
+		struct iso_inode_info *eparent;
+		eparent = ISOFS_I(parent);
+		fh32[3] = eparent->i_iget5_block;
+		fh16[3] = (__u16)eparent->i_iget5_offset;  /* fh16 [sic] */
+		fh32[4] = parent->i_generation;
+		len = 5;
+		type = 2;
+	}
+	*max_len = len;
+	return type;
+}
+
+struct isofs_fid {
+	u32 block;
+	u16 offset;
+	u16 parent_offset;
+	u32 generation;
+	u32 parent_block;
+	u32 parent_generation;
+};
+
+static struct dentry *isofs_fh_to_dentry(struct super_block *sb,
+	struct fid *fid, int fh_len, int fh_type)
+{
+	struct isofs_fid *ifid = (struct isofs_fid *)fid;
+
+	if (fh_len < 3 || fh_type > 2)
+		return NULL;
+
+	return isofs_export_iget(sb, ifid->block, ifid->offset,
+			ifid->generation);
+}
+
+static struct dentry *isofs_fh_to_parent(struct super_block *sb,
+		struct fid *fid, int fh_len, int fh_type)
+{
+	struct isofs_fid *ifid = (struct isofs_fid *)fid;
+
+	if (fh_len < 2 || fh_type != 2)
+		return NULL;
+
+	return isofs_export_iget(sb,
+			fh_len > 2 ? ifid->parent_block : 0,
+			ifid->parent_offset,
+			fh_len > 4 ? ifid->parent_generation : 0);
+}
+
+const struct export_operations isofs_export_ops = {
+	.encode_fh	= isofs_export_encode_fh,
+	.fh_to_dentry	= isofs_fh_to_dentry,
+	.fh_to_parent	= isofs_fh_to_parent,
+	.get_parent     = isofs_export_get_parent,
+};