1 files changed, 251 insertions, 0 deletions
diff --git a/fs/xfs/xfs_export.c b/fs/xfs/xfs_export.c
new file mode 100644
index 0000000000..7cd09c3a82
--- /dev/null
+++ b/fs/xfs/xfs_export.c
@@ -0,0 +1,251 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Copyright (c) 2004-2005 Silicon Graphics, Inc.
+ * All Rights Reserved.
+ */
+#include "xfs.h"
+#include "xfs_shared.h"
+#include "xfs_format.h"
+#include "xfs_log_format.h"
+#include "xfs_trans_resv.h"
+#include "xfs_mount.h"
+#include "xfs_dir2.h"
+#include "xfs_export.h"
+#include "xfs_inode.h"
+#include "xfs_trans.h"
+#include "xfs_inode_item.h"
+#include "xfs_icache.h"
+#include "xfs_pnfs.h"
+
+/*
+ * Note that we only accept fileids which are long enough rather than allow
+ * the parent generation number to default to zero.  XFS considers zero a
+ * valid generation number not an invalid/wildcard value.
+ */
+static int xfs_fileid_length(int fileid_type)
+{
+	switch (fileid_type) {
+	case FILEID_INO32_GEN:
+		return 2;
+	case FILEID_INO32_GEN_PARENT:
+		return 4;
+	case FILEID_INO32_GEN | XFS_FILEID_TYPE_64FLAG:
+		return 3;
+	case FILEID_INO32_GEN_PARENT | XFS_FILEID_TYPE_64FLAG:
+		return 6;
+	}
+	return FILEID_INVALID;
+}
+
+STATIC int
+xfs_fs_encode_fh(
+	struct inode	*inode,
+	__u32		*fh,
+	int		*max_len,
+	struct inode	*parent)
+{
+	struct xfs_mount	*mp = XFS_M(inode->i_sb);
+	struct fid		*fid = (struct fid *)fh;
+	struct xfs_fid64	*fid64 = (struct xfs_fid64 *)fh;
+	int			fileid_type;
+	int			len;
+
+	/* Directories don't need their parent encoded, they have ".." */
+	if (!parent)
+		fileid_type = FILEID_INO32_GEN;
+	else
+		fileid_type = FILEID_INO32_GEN_PARENT;
+
+	/*
+	 * If the filesystem may contain 64bit inode numbers, we need
+	 * to use larger file handles that can represent them.
+	 *
+	 * While we only allocate inodes that do not fit into 32 bits any
+	 * large enough filesystem may contain them, thus the slightly
+	 * confusing looking conditional below.
+	 */
+	if (!xfs_has_small_inums(mp) || xfs_is_inode32(mp))
+		fileid_type |= XFS_FILEID_TYPE_64FLAG;
+
+	/*
+	 * Only encode if there is enough space given.  In practice
+	 * this means we can't export a filesystem with 64bit inodes
+	 * over NFSv2 with the subtree_check export option; the other
+	 * seven combinations work.  The real answer is "don't use v2".
+	 */
+	len = xfs_fileid_length(fileid_type);
+	if (*max_len < len) {
+		*max_len = len;
+		return FILEID_INVALID;
+	}
+	*max_len = len;
+
+	switch (fileid_type) {
+	case FILEID_INO32_GEN_PARENT:
+		fid->i32.parent_ino = XFS_I(parent)->i_ino;
+		fid->i32.parent_gen = parent->i_generation;
+		fallthrough;
+	case FILEID_INO32_GEN:
+		fid->i32.ino = XFS_I(inode)->i_ino;
+		fid->i32.gen = inode->i_generation;
+		break;
+	case FILEID_INO32_GEN_PARENT | XFS_FILEID_TYPE_64FLAG:
+		fid64->parent_ino = XFS_I(parent)->i_ino;
+		fid64->parent_gen = parent->i_generation;
+		fallthrough;
+	case FILEID_INO32_GEN | XFS_FILEID_TYPE_64FLAG:
+		fid64->ino = XFS_I(inode)->i_ino;
+		fid64->gen = inode->i_generation;
+		break;
+	}
+
+	return fileid_type;
+}
+
+STATIC struct inode *
+xfs_nfs_get_inode(
+	struct super_block	*sb,
+	u64			ino,
+	u32			generation)
+{
+ 	xfs_mount_t		*mp = XFS_M(sb);
+	xfs_inode_t		*ip;
+	int			error;
+
+	/*
+	 * NFS can sometimes send requests for ino 0.  Fail them gracefully.
+	 */
+	if (ino == 0)
+		return ERR_PTR(-ESTALE);
+
+	/*
+	 * The XFS_IGET_UNTRUSTED means that an invalid inode number is just
+	 * fine and not an indication of a corrupted filesystem as clients can
+	 * send invalid file handles and we have to handle it gracefully..
+	 */
+	error = xfs_iget(mp, NULL, ino, XFS_IGET_UNTRUSTED, 0, &ip);
+	if (error) {
+
+		/*
+		 * EINVAL means the inode cluster doesn't exist anymore.
+		 * EFSCORRUPTED means the metadata pointing to the inode cluster
+		 * or the inode cluster itself is corrupt.  This implies the
+		 * filehandle is stale, so we should translate it here.
+		 * We don't use ESTALE directly down the chain to not
+		 * confuse applications using bulkstat that expect EINVAL.
+		 */
+		switch (error) {
+		case -EINVAL:
+		case -ENOENT:
+		case -EFSCORRUPTED:
+			error = -ESTALE;
+			break;
+		default:
+			break;
+		}
+		return ERR_PTR(error);
+	}
+
+	/*
+	 * Reload the incore unlinked list to avoid failure in inodegc.
+	 * Use an unlocked check here because unrecovered unlinked inodes
+	 * should be somewhat rare.
+	 */
+	if (xfs_inode_unlinked_incomplete(ip)) {
+		error = xfs_inode_reload_unlinked(ip);
+		if (error) {
+			xfs_force_shutdown(mp, SHUTDOWN_CORRUPT_INCORE);
+			xfs_irele(ip);
+			return ERR_PTR(error);
+		}
+	}
+
+	if (VFS_I(ip)->i_generation != generation) {
+		xfs_irele(ip);
+		return ERR_PTR(-ESTALE);
+	}
+
+	return VFS_I(ip);
+}
+
+STATIC struct dentry *
+xfs_fs_fh_to_dentry(struct super_block *sb, struct fid *fid,
+		 int fh_len, int fileid_type)
+{
+	struct xfs_fid64	*fid64 = (struct xfs_fid64 *)fid;
+	struct inode		*inode = NULL;
+
+	if (fh_len < xfs_fileid_length(fileid_type))
+		return NULL;
+
+	switch (fileid_type) {
+	case FILEID_INO32_GEN_PARENT:
+	case FILEID_INO32_GEN:
+		inode = xfs_nfs_get_inode(sb, fid->i32.ino, fid->i32.gen);
+		break;
+	case FILEID_INO32_GEN_PARENT | XFS_FILEID_TYPE_64FLAG:
+	case FILEID_INO32_GEN | XFS_FILEID_TYPE_64FLAG:
+		inode = xfs_nfs_get_inode(sb, fid64->ino, fid64->gen);
+		break;
+	}
+
+	return d_obtain_alias(inode);
+}
+
+STATIC struct dentry *
+xfs_fs_fh_to_parent(struct super_block *sb, struct fid *fid,
+		 int fh_len, int fileid_type)
+{
+	struct xfs_fid64	*fid64 = (struct xfs_fid64 *)fid;
+	struct inode		*inode = NULL;
+
+	if (fh_len < xfs_fileid_length(fileid_type))
+		return NULL;
+
+	switch (fileid_type) {
+	case FILEID_INO32_GEN_PARENT:
+		inode = xfs_nfs_get_inode(sb, fid->i32.parent_ino,
+					      fid->i32.parent_gen);
+		break;
+	case FILEID_INO32_GEN_PARENT | XFS_FILEID_TYPE_64FLAG:
+		inode = xfs_nfs_get_inode(sb, fid64->parent_ino,
+					      fid64->parent_gen);
+		break;
+	}
+
+	return d_obtain_alias(inode);
+}
+
+STATIC struct dentry *
+xfs_fs_get_parent(
+	struct dentry		*child)
+{
+	int			error;
+	struct xfs_inode	*cip;
+
+	error = xfs_lookup(XFS_I(d_inode(child)), &xfs_name_dotdot, &cip, NULL);
+	if (unlikely(error))
+		return ERR_PTR(error);
+
+	return d_obtain_alias(VFS_I(cip));
+}
+
+STATIC int
+xfs_fs_nfs_commit_metadata(
+	struct inode		*inode)
+{
+	return xfs_log_force_inode(XFS_I(inode));
+}
+
+const struct export_operations xfs_export_operations = {
+	.encode_fh		= xfs_fs_encode_fh,
+	.fh_to_dentry		= xfs_fs_fh_to_dentry,
+	.fh_to_parent		= xfs_fs_fh_to_parent,
+	.get_parent		= xfs_fs_get_parent,
+	.commit_metadata	= xfs_fs_nfs_commit_metadata,
+#ifdef CONFIG_EXPORTFS_BLOCK_OPS
+	.get_uuid		= xfs_fs_get_uuid,
+	.map_blocks		= xfs_fs_map_blocks,
+	.commit_blocks		= xfs_fs_commit_blocks,
+#endif
+};