1 files changed, 115 insertions, 0 deletions

diff --git a/fs/fuse/inode.c b/fs/fuse/inode.c
index 3141690558c8..71fa76a48a31 100644
--- a/fs/fuse/inode.c
+++ b/fs/fuse/inode.c
@@ -18,6 +18,7 @@
 #include <linux/statfs.h>
 #include <linux/random.h>
 #include <linux/sched.h>
+#include <linux/exportfs.h>
 
 MODULE_AUTHOR("Miklos Szeredi <miklos@szeredi.hu>");
 MODULE_DESCRIPTION("Filesystem in Userspace");
@@ -552,6 +553,119 @@ static struct inode *get_root_inode(struct super_block *sb, unsigned mode)
         return fuse_iget(sb, 1, 0, &attr, 0, 0);
 }
 
+struct fuse_inode_handle
+{
+        u64 nodeid;
+        u32 generation;
+};
+
+static struct dentry *fuse_get_dentry(struct super_block *sb,
+                                      struct fuse_inode_handle *handle)
+{
+        struct inode *inode;
+        struct dentry *entry;
+        int err = -ESTALE;
+
+        if (handle->nodeid == 0)
+                goto out_err;
+
+        inode = ilookup5(sb, handle->nodeid, fuse_inode_eq, &handle->nodeid);
+        if (!inode)
+                goto out_err;
+        err = -ESTALE;
+        if (inode->i_generation != handle->generation)
+                goto out_iput;
+
+        entry = d_alloc_anon(inode);
+        err = -ENOMEM;
+        if (!entry)
+                goto out_iput;
+
+        if (get_node_id(inode) != FUSE_ROOT_ID) {
+                entry->d_op = &fuse_dentry_operations;
+                fuse_invalidate_entry_cache(entry);
+        }
+
+        return entry;
+
+ out_iput:
+        iput(inode);
+ out_err:
+        return ERR_PTR(err);
+}
+
+static int fuse_encode_fh(struct dentry *dentry, u32 *fh, int *max_len,
+                           int connectable)
+{
+        struct inode *inode = dentry->d_inode;
+        bool encode_parent = connectable && !S_ISDIR(inode->i_mode);
+        int len = encode_parent ? 6 : 3;
+        u64 nodeid;
+        u32 generation;
+
+        if (*max_len < len)
+                return  255;
+
+        nodeid = get_fuse_inode(inode)->nodeid;
+        generation = inode->i_generation;
+
+        fh[0] = (u32)(nodeid >> 32);
+        fh[1] = (u32)(nodeid & 0xffffffff);
+        fh[2] = generation;
+
+        if (encode_parent) {
+                struct inode *parent;
+
+                spin_lock(&dentry->d_lock);
+                parent = dentry->d_parent->d_inode;
+                nodeid = get_fuse_inode(parent)->nodeid;
+                generation = parent->i_generation;
+                spin_unlock(&dentry->d_lock);
+
+                fh[3] = (u32)(nodeid >> 32);
+                fh[4] = (u32)(nodeid & 0xffffffff);
+                fh[5] = generation;
+        }
+
+        *max_len = len;
+        return encode_parent ? 0x82 : 0x81;
+}
+
+static struct dentry *fuse_fh_to_dentry(struct super_block *sb,
+                struct fid *fid, int fh_len, int fh_type)
+{
+        struct fuse_inode_handle handle;
+
+        if ((fh_type != 0x81 && fh_type != 0x82) || fh_len < 3)
+                return NULL;
+
+        handle.nodeid = (u64) fid->raw[0] << 32;
+        handle.nodeid |= (u64) fid->raw[1];
+        handle.generation = fid->raw[2];
+        return fuse_get_dentry(sb, &handle);
+}
+
+static struct dentry *fuse_fh_to_parent(struct super_block *sb,
+                struct fid *fid, int fh_len, int fh_type)
+{
+        struct fuse_inode_handle parent;
+
+        if (fh_type != 0x82 || fh_len < 6)
+                return NULL;
+
+        parent.nodeid = (u64) fid->raw[3] << 32;
+        parent.nodeid |= (u64) fid->raw[4];
+        parent.generation = fid->raw[5];
+        return fuse_get_dentry(sb, &parent);
+}
+
+
+static const struct export_operations fuse_export_operations = {
+        .fh_to_dentry   = fuse_fh_to_dentry,
+        .fh_to_parent   = fuse_fh_to_parent,
+        .encode_fh      = fuse_encode_fh,
+};
+
 static const struct super_operations fuse_super_operations = {
         .alloc_inode    = fuse_alloc_inode,
         .destroy_inode  = fuse_destroy_inode,
@@ -652,6 +766,7 @@ static int fuse_fill_super(struct super_block *sb, void *data, int silent)
         sb->s_magic = FUSE_SUPER_MAGIC;
         sb->s_op = &fuse_super_operations;
         sb->s_maxbytes = MAX_LFS_FILESIZE;
+        sb->s_export_op = &fuse_export_operations;
 
         file = fget(d.fd);
         if (!file)