f601f9a2bf
kernfs_unmap_bin_file() is supposed to unmap all memory mappings of
the target file before kernfs_remove() finishes; however, it currently
is being called from kernfs_addrm_finish() and has the same race
problem as the original implementation of deactivation when there are
multiple removers - only the remover which snatches the node to its
addrm_cxt->removed list is guaranteed to wait for its completion
before returning.
It can be fixed by moving kernfs_unmap_bin_file() invocation from
kernfs_addrm_finish() to __kernfs_remove(). The function may be
called multiple times but that shouldn't do any harm.
We end up dropping kernfs_mutex in the removal loop and the node may
be removed inbetween by someone else. kernfs_unlink_sibling() is
updated to test whether the node has already been removed and return
accordingly. __kernfs_remove() in turn performs post-unlinking
cleanup only if it actually unlinked the node.
KERNFS_HAS_MMAP test is moved out of the unmap function into
__kernfs_remove() so that we don't unlock kernfs_mutex unnecessarily.
While at it, drop the now meaningless "bin" qualifier from the
function name.
v2: Rewritten to fit the v2 restructuring of removal path. HAS_MMAP
test relocated.
Signed-off-by: Tejun Heo <tj@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
123 lines
3.4 KiB
C
123 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_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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