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81c173cb5e
KERNFS_REMOVED is used to mark half-initialized and dying nodes so
that they don't show up in lookups and deny adding new nodes under or
renaming it; however, its role overlaps that of deactivation.
It's necessary to deny addition of new children while removal is in
progress; however, this role considerably intersects with deactivation
- KERNFS_REMOVED prevents new children while deactivation prevents new
file operations. There's no reason to have them separate making
things more complex than necessary.
This patch removes KERNFS_REMOVED.
* Instead of KERNFS_REMOVED, each node now starts its life
deactivated. This means that we now use both atomic_add() and
atomic_sub() on KN_DEACTIVATED_BIAS, which is INT_MIN. The compiler
generates an overflow warnings when negating INT_MIN as the negation
can't be represented as a positive number. Nothing is actually
broken but let's bump BIAS by one to avoid the warnings for archs
which negates the subtrahend..
* A new helper kernfs_active() which tests whether kn->active >= 0 is
added for convenience and lockdep annotation. All KERNFS_REMOVED
tests are replaced with negated kernfs_active() tests.
* __kernfs_remove() is updated to deactivate, but not drain, all nodes
in the subtree instead of setting KERNFS_REMOVED. This removes
deactivation from kernfs_deactivate(), which is now renamed to
kernfs_drain().
* Sanity check on KERNFS_REMOVED in kernfs_put() is replaced with
checks on the active ref.
* Some comment style updates in the affected area.
v2: Reordered before removal path restructuring. kernfs_active()
dropped and kernfs_get/put_active() used instead. RB_EMPTY_NODE()
used in the lookup paths.
v3: Reverted most of v2 except for creating a new node with
KN_DEACTIVATED_BIAS.
Signed-off-by: Tejun Heo <tj@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
114 lines
3.1 KiB
C
114 lines
3.1 KiB
C
/*
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* fs/kernfs/kernfs-internal.h - kernfs internal header file
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*
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* Copyright (c) 2001-3 Patrick Mochel
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* Copyright (c) 2007 SUSE Linux Products GmbH
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* Copyright (c) 2007, 2013 Tejun Heo <teheo@suse.de>
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*
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* This file is released under the GPLv2.
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*/
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#ifndef __KERNFS_INTERNAL_H
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#define __KERNFS_INTERNAL_H
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#include <linux/lockdep.h>
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#include <linux/fs.h>
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#include <linux/mutex.h>
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#include <linux/xattr.h>
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#include <linux/kernfs.h>
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struct kernfs_iattrs {
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struct iattr ia_iattr;
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void *ia_secdata;
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u32 ia_secdata_len;
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struct simple_xattrs xattrs;
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};
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/* +1 to avoid triggering overflow warning when negating it */
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#define KN_DEACTIVATED_BIAS (INT_MIN + 1)
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/* KERNFS_TYPE_MASK and types are defined in include/linux/kernfs.h */
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/**
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* kernfs_root - find out the kernfs_root a kernfs_node belongs to
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* @kn: kernfs_node of interest
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*
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* Return the kernfs_root @kn belongs to.
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*/
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static inline struct kernfs_root *kernfs_root(struct kernfs_node *kn)
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{
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/* if parent exists, it's always a dir; otherwise, @sd is a dir */
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if (kn->parent)
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kn = kn->parent;
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return kn->dir.root;
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}
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/*
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* mount.c
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*/
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struct kernfs_super_info {
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/*
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* The root associated with this super_block. Each super_block is
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* identified by the root and ns it's associated with.
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*/
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struct kernfs_root *root;
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/*
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* Each sb is associated with one namespace tag, currently the
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* network namespace of the task which mounted this kernfs
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* instance. If multiple tags become necessary, make the following
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* an array and compare kernfs_node tag against every entry.
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*/
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const void *ns;
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};
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#define kernfs_info(SB) ((struct kernfs_super_info *)(SB->s_fs_info))
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extern struct kmem_cache *kernfs_node_cache;
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/*
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* inode.c
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*/
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struct inode *kernfs_get_inode(struct super_block *sb, struct kernfs_node *kn);
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void kernfs_evict_inode(struct inode *inode);
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int kernfs_iop_permission(struct inode *inode, int mask);
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int kernfs_iop_setattr(struct dentry *dentry, struct iattr *iattr);
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int kernfs_iop_getattr(struct vfsmount *mnt, struct dentry *dentry,
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struct kstat *stat);
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int kernfs_iop_setxattr(struct dentry *dentry, const char *name, const void *value,
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size_t size, int flags);
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int kernfs_iop_removexattr(struct dentry *dentry, const char *name);
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ssize_t kernfs_iop_getxattr(struct dentry *dentry, const char *name, void *buf,
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size_t size);
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ssize_t kernfs_iop_listxattr(struct dentry *dentry, char *buf, size_t size);
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void kernfs_inode_init(void);
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/*
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* dir.c
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*/
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extern struct mutex kernfs_mutex;
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extern const struct dentry_operations kernfs_dops;
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extern const struct file_operations kernfs_dir_fops;
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extern const struct inode_operations kernfs_dir_iops;
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struct kernfs_node *kernfs_get_active(struct kernfs_node *kn);
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void kernfs_put_active(struct kernfs_node *kn);
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int kernfs_add_one(struct kernfs_node *kn);
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struct kernfs_node *kernfs_new_node(struct kernfs_node *parent,
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const char *name, umode_t mode,
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unsigned flags);
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/*
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* file.c
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*/
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extern const struct file_operations kernfs_file_fops;
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void kernfs_unmap_bin_file(struct kernfs_node *kn);
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/*
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* symlink.c
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*/
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extern const struct inode_operations kernfs_symlink_iops;
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#endif /* __KERNFS_INTERNAL_H */
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