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ae34372eb8
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 those of deactivation and
removal from rbtree.
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.
KERNFS_REMOVED is also used to decide whether a node is still visible
to vfs layer, which is rather redundant as equivalent determination
can be made by testing whether the node is on its parent's children
rbtree or not.
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..
* KERNFS_REMOVED tests in add and rename paths are replaced with
kernfs_get/put_active() of the target nodes. Due to the way the add
path is structured now, active ref handling is done in the callers
of kernfs_add_one(). This will be consolidated up later.
* kernfs_remove_one() is updated to deactivate instead of setting
KERNFS_REMOVED. This removes deactivation from kernfs_deactivate(),
which is now renamed to kernfs_drain().
* kernfs_dop_revalidate() now tests RB_EMPTY_NODE(&kn->rb) instead of
KERNFS_REMOVED and KERNFS_REMOVED test in kernfs_dir_pos() is
dropped. A node which is removed from the children rbtree is not
included in the iteration in the first place. This means that a
node may be visible through vfs a bit longer - it's now also visible
after deactivation until the actual removal. This slightly enlarged
window difference doesn't make any difference to the userland.
* 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.
Signed-off-by: Tejun Heo <tj@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
124 lines
3.4 KiB
C
124 lines
3.4 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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* Context structure to be used while adding/removing nodes.
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*/
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struct kernfs_addrm_cxt {
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struct kernfs_node *removed;
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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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void kernfs_addrm_start(struct kernfs_addrm_cxt *acxt);
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int kernfs_add_one(struct kernfs_addrm_cxt *acxt, struct kernfs_node *kn,
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struct kernfs_node *parent);
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void kernfs_addrm_finish(struct kernfs_addrm_cxt *acxt);
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struct kernfs_node *kernfs_new_node(struct kernfs_root *root, const char *name,
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umode_t mode, 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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