Commit 33c5ac91 authored by Tejun Heo's avatar Tejun Heo
Browse files

kernfs: implement custom exportfs ops and fid type 



The current kernfs exportfs implementation uses the generic_fh_*()
helpers and FILEID_INO32_GEN[_PARENT] which limits ino to 32bits.
Let's implement custom exportfs operations and fid type to remove the
restriction.

* FILEID_KERNFS is a single u64 value whose content is
  kernfs_node->id.  This is the only native fid type.

* For backward compatibility with blk_log_action() path which exposes
  (ino,gen) pairs which userland assembles into FILEID_INO32_GEN keys,
  combine the generic keys into 64bit IDs in the same order.

Signed-off-by: default avatarTejun Heo <tj@kernel.org>
Reviewed-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: Namhyung Kim <namhyung@kernel.org>
parent fe0f726c

fs/kernfs/mount.c

+61 −16
Original line number Diff line number Diff line
@@ -53,40 +53,84 @@ 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)

static int kernfs_encode_fh(struct inode *inode, __u32 *fh, int *max_len,

			    struct inode *parent)

{

	struct kernfs_node *kn = inode->i_private;



	if (*max_len < 2) {

		*max_len = 2;

		return FILEID_INVALID;

	}



	*max_len = 2;

	*(u64 *)fh = kn->id;

	return FILEID_KERNFS;

}



static struct dentry *__kernfs_fh_to_dentry(struct super_block *sb,

					    struct fid *fid, int fh_len,

					    int fh_type, bool get_parent)

{

	struct kernfs_super_info *info = kernfs_info(sb);

	struct inode *inode;

	struct kernfs_node *kn;

	struct inode *inode;

	u64 id;



	if (fh_len < 2)

		return NULL;



	if (ino == 0)

	switch (fh_type) {

	case FILEID_KERNFS:

		id = *(u64 *)fid;

		break;

	case FILEID_INO32_GEN:

	case FILEID_INO32_GEN_PARENT:

		/*

		 * blk_log_action() exposes (ino,gen) pair without type and

		 * userland can call us with generic fid constructed from

		 * them.  Combine it back to ID.  See blk_log_action().

		 */

		id = ((u64)fid->i32.gen << 32) | fid->i32.ino;

		break;

	default:

		return NULL;

	}



	kn = kernfs_find_and_get_node_by_id(info->root, id);

	if (!kn)

		return ERR_PTR(-ESTALE);



	kn = kernfs_find_and_get_node_by_id(info->root,

					    ino | ((u64)generation << 32));

	if (get_parent) {

		struct kernfs_node *parent;



		parent = kernfs_get_parent(kn);

		kernfs_put(kn);

		kn = parent;

		if (!kn)

			return ERR_PTR(-ESTALE);

	}



	inode = kernfs_get_inode(sb, kn);

	kernfs_put(kn);

	if (!inode)

		return ERR_PTR(-ESTALE);



	return inode;

	return d_obtain_alias(inode);

}



static struct dentry *kernfs_fh_to_dentry(struct super_block *sb, struct fid *fid,

		int fh_len, int fh_type)

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);

	return __kernfs_fh_to_dentry(sb, fid, fh_len, fh_type, false);

}



static struct dentry *kernfs_fh_to_parent(struct super_block *sb, struct fid *fid,

		int fh_len, int fh_type)

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);

	return __kernfs_fh_to_dentry(sb, fid, fh_len, fh_type, true);

}



static struct dentry *kernfs_get_parent_dentry(struct dentry *child)
@@ -97,6 +141,7 @@ static struct dentry *kernfs_get_parent_dentry(struct dentry *child) 
}



static const struct export_operations kernfs_export_ops = {

	.encode_fh	= kernfs_encode_fh,

	.fh_to_dentry	= kernfs_fh_to_dentry,

	.fh_to_parent	= kernfs_fh_to_parent,

	.get_parent	= kernfs_get_parent_dentry,

include/linux/exportfs.h

+5 −0
Original line number Diff line number Diff line
@@ -104,6 +104,11 @@ enum fid_type { 
	 */

	FILEID_LUSTRE = 0x97,



	/*

	 * 64 bit unique kernfs id

	 */

	FILEID_KERNFS = 0xfe,



	/*

	 * Filesystems must not use 0xff file ID.

	 */

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