From 33c5ac9175195c36a0b7005aaf503a2e81f117a1 Mon Sep 17 00:00:00 2001 From: Tejun Heo Date: Mon, 4 Nov 2019 15:54:30 -0800 Subject: [PATCH] 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: Tejun Heo Reviewed-by: Greg Kroah-Hartman Cc: Namhyung Kim --- fs/kernfs/mount.c | 77 +++++++++++++++++++++++++++++++--------- include/linux/exportfs.h | 5 +++ 2 files changed, 66 insertions(+), 16 deletions(-) diff --git a/fs/kernfs/mount.c b/fs/kernfs/mount.c index 8aed2cccd002..37a1e5df117a 100644 --- a/fs/kernfs/mount.c +++ b/fs/kernfs/mount.c @@ -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 (ino == 0) - return ERR_PTR(-ESTALE); + if (fh_len < 2) + return NULL; + + 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, - ino | ((u64)generation << 32)); + kn = kernfs_find_and_get_node_by_id(info->root, id); if (!kn) return ERR_PTR(-ESTALE); + + 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, diff --git a/include/linux/exportfs.h b/include/linux/exportfs.h index cf6571fc9c01..d896b8657085 100644 --- a/include/linux/exportfs.h +++ b/include/linux/exportfs.h @@ -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. */ -- 2.30.2