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-rw-r--r--fs/kernfs/mount.c56
1 files changed, 56 insertions, 0 deletions
diff --git a/fs/kernfs/mount.c b/fs/kernfs/mount.c
index acd542625fd8..fa323589704f 100644
--- a/fs/kernfs/mount.c
+++ b/fs/kernfs/mount.c
@@ -16,6 +16,7 @@
#include <linux/pagemap.h>
#include <linux/namei.h>
#include <linux/seq_file.h>
+#include <linux/exportfs.h>
#include "kernfs-internal.h"
@@ -64,6 +65,59 @@ const struct super_operations kernfs_sops = {
.show_path = kernfs_sop_show_path,
};
+static struct inode *kernfs_fh_get_inode(struct super_block *sb,
+ u64 ino, u32 generation)
+{
+ struct kernfs_super_info *info = kernfs_info(sb);
+ struct inode *inode;
+ struct kernfs_node *kn;
+
+ if (ino == 0)
+ return ERR_PTR(-ESTALE);
+
+ kn = kernfs_find_and_get_node_by_ino(info->root, ino);
+ if (!kn)
+ return ERR_PTR(-ESTALE);
+ inode = kernfs_get_inode(sb, kn);
+ kernfs_put(kn);
+ if (IS_ERR(inode))
+ return ERR_CAST(inode);
+
+ if (generation && inode->i_generation != generation) {
+ /* we didn't find the right inode.. */
+ iput(inode);
+ return ERR_PTR(-ESTALE);
+ }
+ return inode;
+}
+
+static struct dentry *kernfs_fh_to_dentry(struct super_block *sb, struct fid *fid,
+ int fh_len, int fh_type)
+{
+ return generic_fh_to_dentry(sb, fid, fh_len, fh_type,
+ kernfs_fh_get_inode);
+}
+
+static struct dentry *kernfs_fh_to_parent(struct super_block *sb, struct fid *fid,
+ int fh_len, int fh_type)
+{
+ return generic_fh_to_parent(sb, fid, fh_len, fh_type,
+ kernfs_fh_get_inode);
+}
+
+static struct dentry *kernfs_get_parent_dentry(struct dentry *child)
+{
+ struct kernfs_node *kn = kernfs_dentry_node(child);
+
+ return d_obtain_alias(kernfs_get_inode(child->d_sb, kn->parent));
+}
+
+static const struct export_operations kernfs_export_ops = {
+ .fh_to_dentry = kernfs_fh_to_dentry,
+ .fh_to_parent = kernfs_fh_to_parent,
+ .get_parent = kernfs_get_parent_dentry,
+};
+
/**
* kernfs_root_from_sb - determine kernfs_root associated with a super_block
* @sb: the super_block in question
@@ -159,6 +213,8 @@ static int kernfs_fill_super(struct super_block *sb, unsigned long magic)
sb->s_magic = magic;
sb->s_op = &kernfs_sops;
sb->s_xattr = kernfs_xattr_handlers;
+ if (info->root->flags & KERNFS_ROOT_SUPPORT_EXPORTOP)
+ sb->s_export_op = &kernfs_export_ops;
sb->s_time_gran = 1;
/* get root inode, initialize and unlock it */