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Subject[PATCH] knfsd: add nfs-export support to ramfs
Date
Refer to tmpfs, use inode number and generation number
to construct the filehandle for nfs-export

Signed-off-by: Haodong Wong <haydenw.kernel@gmail.com>
---
fs/ramfs/inode.c | 72 ++++++++++++++++++++++++++++++++++++++++++++++++
1 file changed, 72 insertions(+)

diff --git a/fs/ramfs/inode.c b/fs/ramfs/inode.c
index 11201b2d06b9..418b2551f6fd 100644
--- a/fs/ramfs/inode.c
+++ b/fs/ramfs/inode.c
@@ -36,6 +36,7 @@
#include <linux/magic.h>
#include <linux/slab.h>
#include <linux/uaccess.h>
+#include <linux/exportfs.h>
#include "internal.h"

struct ramfs_mount_opts {
@@ -66,6 +67,7 @@ struct inode *ramfs_get_inode(struct super_block *sb,
if (inode) {
inode->i_ino = get_next_ino();
inode_init_owner(inode, dir, mode);
+ inode->i_generation = get_seconds();
inode->i_mapping->a_ops = &ramfs_aops;
mapping_set_gfp_mask(inode->i_mapping, GFP_HIGHUSER);
mapping_set_unevictable(inode->i_mapping);
@@ -217,6 +219,75 @@ static int ramfs_parse_options(char *data, struct ramfs_mount_opts *opts)
return 0;
}

+static struct dentry *ramfs_get_parent(struct dentry *child)
+{
+ return ERR_PTR(-ESTALE);
+}
+
+static int ramfs_match(struct inode *ino, void *vfh)
+{
+ __u32 *fh = vfh;
+ __u64 inum = fh[2];
+
+ inum = (inum << 32) | fh[1];
+ return ino->i_ino == inum && fh[0] == ino->i_generation;
+}
+
+static struct dentry *ramfs_fh_to_dentry(struct super_block *sb,
+ struct fid *fid, int fh_len, int fh_type)
+
+{
+ struct inode *inode;
+ struct dentry *dentry = NULL;
+ u64 inum;
+
+ if (fh_len < 3)
+ return NULL;
+
+ inum = fid->raw[2];
+ inum = (inum << 32) | fid->raw[1];
+ inode = ilookup5(sb, (unsigned long)(inum + fid->raw[0]),
+ ramfs_match, fid->raw);
+
+ if (inode) {
+ dentry = d_find_alias(inode);
+ iput(inode);
+ }
+
+ return dentry;
+}
+
+static int ramfs_encode_fh(struct inode *inode, __u32 *fh, int *len,
+ struct inode *parent)
+{
+ if (*len < 3) {
+ *len = 3;
+ return FILEID_INVALID;
+ }
+
+ if (inode_unhashed(inode)) {
+ static DEFINE_SPINLOCK(lock);
+
+ spin_lock(&lock);
+ if (inode_unhashed(inode))
+ __insert_inode_hash(inode,
+ inode->i_ino + inode->i_generation);
+ spin_unlock(&lock);
+ }
+ fh[0] = inode->i_generation;
+ fh[1] = inode->i_ino;
+ fh[2] = ((__u64)inode->i_ino) >> 32;
+
+ *len = 3;
+ return 1;
+}
+
+static const struct export_operations ramfs_export_ops = {
+ .get_parent = ramfs_get_parent,
+ .encode_fh = ramfs_encode_fh,
+ .fh_to_dentry = ramfs_fh_to_dentry,
+};
+
int ramfs_fill_super(struct super_block *sb, void *data, int silent)
{
struct ramfs_fs_info *fsi;
@@ -238,6 +309,7 @@ int ramfs_fill_super(struct super_block *sb, void *data, int silent)
sb->s_magic = RAMFS_MAGIC;
sb->s_op = &ramfs_ops;
sb->s_time_gran = 1;
+ sb->s_export_op = &ramfs_export_ops;

inode = ramfs_get_inode(sb, NULL, S_IFDIR | fsi->mount_opts.mode, 0);
sb->s_root = d_make_root(inode);
--
2.17.1
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