From fe0f726c9fb626b1092a9ea3bf75f57f2eed676e Mon Sep 17 00:00:00 2001 From: Tejun Heo Date: Mon, 4 Nov 2019 15:54:30 -0800 Subject: [PATCH] kernfs: combine ino/id lookup functions into kernfs_find_and_get_node_by_id() kernfs_find_and_get_node_by_ino() looks the kernfs_node matching the specified ino. On top of that, kernfs_get_node_by_id() and kernfs_fh_get_inode() implement full ID matching by testing the rest of ID. On surface, confusingly, the two are slightly different in that the latter uses 0 gen as wildcard while the former doesn't - does it mean that the latter can't uniquely identify inodes w/ 0 gen? In practice, this is a distinction without a difference because generation number starts at 1. There are no actual IDs with 0 gen, so it can always safely used as wildcard. Let's simplify the code by renaming kernfs_find_and_get_node_by_ino() to kernfs_find_and_get_node_by_id(), moving all lookup logics into it, and removing now unnecessary kernfs_get_node_by_id(). Signed-off-by: Tejun Heo Reviewed-by: Greg Kroah-Hartman --- fs/kernfs/dir.c | 17 +++++++++++++---- fs/kernfs/kernfs-internal.h | 2 -- fs/kernfs/mount.c | 26 ++------------------------ include/linux/kernfs.h | 3 ++- kernel/cgroup/cgroup.c | 2 +- 5 files changed, 18 insertions(+), 32 deletions(-) diff --git a/fs/kernfs/dir.c b/fs/kernfs/dir.c index c67afb591e5b..5dcf19d4adbc 100644 --- a/fs/kernfs/dir.c +++ b/fs/kernfs/dir.c @@ -696,17 +696,22 @@ struct kernfs_node *kernfs_new_node(struct kernfs_node *parent, } /* - * kernfs_find_and_get_node_by_ino - get kernfs_node from inode number + * kernfs_find_and_get_node_by_id - get kernfs_node from node id * @root: the kernfs root - * @ino: inode number + * @id: the target node id + * + * @id's lower 32bits encode ino and upper gen. If the gen portion is + * zero, all generations are matched. * * RETURNS: * NULL on failure. Return a kernfs node with reference counter incremented */ -struct kernfs_node *kernfs_find_and_get_node_by_ino(struct kernfs_root *root, - unsigned int ino) +struct kernfs_node *kernfs_find_and_get_node_by_id(struct kernfs_root *root, + u64 id) { struct kernfs_node *kn; + ino_t ino = kernfs_id_ino(id); + u32 gen = kernfs_id_gen(id); spin_lock(&kernfs_idr_lock); @@ -714,6 +719,10 @@ struct kernfs_node *kernfs_find_and_get_node_by_ino(struct kernfs_root *root, if (!kn) goto err_unlock; + /* 0 matches all generations */ + if (unlikely(gen && kernfs_gen(kn) != gen)) + goto err_unlock; + /* * ACTIVATED is protected with kernfs_mutex but it was clear when * @kn was added to idr and we just wanna see it set. No need to diff --git a/fs/kernfs/kernfs-internal.h b/fs/kernfs/kernfs-internal.h index 02ce570a9a3c..2f3c51d55261 100644 --- a/fs/kernfs/kernfs-internal.h +++ b/fs/kernfs/kernfs-internal.h @@ -109,8 +109,6 @@ struct kernfs_node *kernfs_new_node(struct kernfs_node *parent, const char *name, umode_t mode, kuid_t uid, kgid_t gid, unsigned flags); -struct kernfs_node *kernfs_find_and_get_node_by_ino(struct kernfs_root *root, - unsigned int ino); /* * file.c diff --git a/fs/kernfs/mount.c b/fs/kernfs/mount.c index f05d5d6f926d..8aed2cccd002 100644 --- a/fs/kernfs/mount.c +++ b/fs/kernfs/mount.c @@ -53,24 +53,6 @@ const struct super_operations kernfs_sops = { .show_path = kernfs_sop_show_path, }; -/* - * Similar to kernfs_fh_get_inode, this one gets kernfs node from inode - * number and generation - */ -struct kernfs_node *kernfs_get_node_by_id(struct kernfs_root *root, u64 id) -{ - struct kernfs_node *kn; - - kn = kernfs_find_and_get_node_by_ino(root, kernfs_id_ino(id)); - if (!kn) - return NULL; - if (kernfs_gen(kn) != kernfs_id_gen(id)) { - kernfs_put(kn); - return NULL; - } - return kn; -} - static struct inode *kernfs_fh_get_inode(struct super_block *sb, u64 ino, u32 generation) { @@ -81,7 +63,8 @@ static struct inode *kernfs_fh_get_inode(struct super_block *sb, if (ino == 0) return ERR_PTR(-ESTALE); - kn = kernfs_find_and_get_node_by_ino(info->root, ino); + kn = kernfs_find_and_get_node_by_id(info->root, + ino | ((u64)generation << 32)); if (!kn) return ERR_PTR(-ESTALE); inode = kernfs_get_inode(sb, kn); @@ -89,11 +72,6 @@ static struct inode *kernfs_fh_get_inode(struct super_block *sb, if (!inode) return ERR_PTR(-ESTALE); - if (generation && inode->i_generation != generation) { - /* we didn't find the right inode.. */ - iput(inode); - return ERR_PTR(-ESTALE); - } return inode; } diff --git a/include/linux/kernfs.h b/include/linux/kernfs.h index b2fc5c8ef6d9..38267cc9420c 100644 --- a/include/linux/kernfs.h +++ b/include/linux/kernfs.h @@ -393,7 +393,8 @@ void kernfs_kill_sb(struct super_block *sb); void kernfs_init(void); -struct kernfs_node *kernfs_get_node_by_id(struct kernfs_root *root, u64 id); +struct kernfs_node *kernfs_find_and_get_node_by_id(struct kernfs_root *root, + u64 id); #else /* CONFIG_KERNFS */ static inline enum kernfs_node_type kernfs_type(struct kernfs_node *kn) diff --git a/kernel/cgroup/cgroup.c b/kernel/cgroup/cgroup.c index c6bd1a5a1977..b5dcbee5aa6c 100644 --- a/kernel/cgroup/cgroup.c +++ b/kernel/cgroup/cgroup.c @@ -5790,7 +5790,7 @@ void cgroup_path_from_kernfs_id(u64 id, char *buf, size_t buflen) { struct kernfs_node *kn; - kn = kernfs_get_node_by_id(cgrp_dfl_root.kf_root, id); + kn = kernfs_find_and_get_node_by_id(cgrp_dfl_root.kf_root, id); if (!kn) return; kernfs_path(kn, buf, buflen);