Commit fe0f726c authored by Tejun Heo's avatar Tejun Heo
Browse files

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: default avatarTejun Heo <tj@kernel.org>
Reviewed-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
parent 67c0496e

fs/kernfs/dir.c

+13 −4
Original line number Diff line number Diff line
@@ -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

fs/kernfs/kernfs-internal.h

+0 −2
Original line number Diff line number Diff line
@@ -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

fs/kernfs/mount.c

+2 −24
Original line number Diff line number Diff line
@@ -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;

}

include/linux/kernfs.h

+2 −1
Original line number Diff line number Diff line
@@ -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)

kernel/cgroup/cgroup.c

+1 −1
Original line number Diff line number Diff line
@@ -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);

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