![Arjan van de Ven](/assets/img/avatar_default.png)
sysfs has a different i_mutex lock order behavior for i_mutex than the other filesystems; sysfs i_mutex is called in many places with subsystem locks held. At the same time, many of the VFS locking rules do not apply to sysfs at all (cross directory rename for example). To untangle this mess (which gives false positives in lockdep), we're giving sysfs inodes their own class for i_mutex. Signed-off-by: Arjan van de Ven <arjan@linux.intel.com> Cc: Ingo Molnar <mingo@elte.hu> Cc: Greg KH <greg@kroah.com> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
263 lines
6.4 KiB
C
263 lines
6.4 KiB
C
/*
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* inode.c - basic inode and dentry operations.
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*
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* sysfs is Copyright (c) 2001-3 Patrick Mochel
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*
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* Please see Documentation/filesystems/sysfs.txt for more information.
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*/
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#undef DEBUG
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#include <linux/pagemap.h>
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#include <linux/namei.h>
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#include <linux/backing-dev.h>
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#include <linux/capability.h>
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#include "sysfs.h"
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extern struct super_block * sysfs_sb;
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static const struct address_space_operations sysfs_aops = {
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.readpage = simple_readpage,
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.prepare_write = simple_prepare_write,
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.commit_write = simple_commit_write
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};
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static struct backing_dev_info sysfs_backing_dev_info = {
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.ra_pages = 0, /* No readahead */
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.capabilities = BDI_CAP_NO_ACCT_DIRTY | BDI_CAP_NO_WRITEBACK,
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};
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static struct inode_operations sysfs_inode_operations ={
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.setattr = sysfs_setattr,
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};
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int sysfs_setattr(struct dentry * dentry, struct iattr * iattr)
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{
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struct inode * inode = dentry->d_inode;
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struct sysfs_dirent * sd = dentry->d_fsdata;
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struct iattr * sd_iattr;
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unsigned int ia_valid = iattr->ia_valid;
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int error;
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if (!sd)
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return -EINVAL;
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sd_iattr = sd->s_iattr;
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error = inode_change_ok(inode, iattr);
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if (error)
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return error;
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error = inode_setattr(inode, iattr);
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if (error)
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return error;
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if (!sd_iattr) {
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/* setting attributes for the first time, allocate now */
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sd_iattr = kzalloc(sizeof(struct iattr), GFP_KERNEL);
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if (!sd_iattr)
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return -ENOMEM;
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/* assign default attributes */
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sd_iattr->ia_mode = sd->s_mode;
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sd_iattr->ia_uid = 0;
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sd_iattr->ia_gid = 0;
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sd_iattr->ia_atime = sd_iattr->ia_mtime = sd_iattr->ia_ctime = CURRENT_TIME;
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sd->s_iattr = sd_iattr;
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}
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/* attributes were changed atleast once in past */
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if (ia_valid & ATTR_UID)
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sd_iattr->ia_uid = iattr->ia_uid;
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if (ia_valid & ATTR_GID)
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sd_iattr->ia_gid = iattr->ia_gid;
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if (ia_valid & ATTR_ATIME)
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sd_iattr->ia_atime = timespec_trunc(iattr->ia_atime,
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inode->i_sb->s_time_gran);
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if (ia_valid & ATTR_MTIME)
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sd_iattr->ia_mtime = timespec_trunc(iattr->ia_mtime,
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inode->i_sb->s_time_gran);
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if (ia_valid & ATTR_CTIME)
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sd_iattr->ia_ctime = timespec_trunc(iattr->ia_ctime,
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inode->i_sb->s_time_gran);
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if (ia_valid & ATTR_MODE) {
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umode_t mode = iattr->ia_mode;
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if (!in_group_p(inode->i_gid) && !capable(CAP_FSETID))
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mode &= ~S_ISGID;
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sd_iattr->ia_mode = sd->s_mode = mode;
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}
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return error;
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}
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static inline void set_default_inode_attr(struct inode * inode, mode_t mode)
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{
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inode->i_mode = mode;
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inode->i_uid = 0;
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inode->i_gid = 0;
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inode->i_atime = inode->i_mtime = inode->i_ctime = CURRENT_TIME;
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}
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static inline void set_inode_attr(struct inode * inode, struct iattr * iattr)
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{
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inode->i_mode = iattr->ia_mode;
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inode->i_uid = iattr->ia_uid;
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inode->i_gid = iattr->ia_gid;
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inode->i_atime = iattr->ia_atime;
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inode->i_mtime = iattr->ia_mtime;
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inode->i_ctime = iattr->ia_ctime;
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}
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/*
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* sysfs has a different i_mutex lock order behavior for i_mutex than other
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* filesystems; sysfs i_mutex is called in many places with subsystem locks
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* held. At the same time, many of the VFS locking rules do not apply to
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* sysfs at all (cross directory rename for example). To untangle this mess
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* (which gives false positives in lockdep), we're giving sysfs inodes their
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* own class for i_mutex.
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*/
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static struct lock_class_key sysfs_inode_imutex_key;
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struct inode * sysfs_new_inode(mode_t mode, struct sysfs_dirent * sd)
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{
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struct inode * inode = new_inode(sysfs_sb);
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if (inode) {
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inode->i_blksize = PAGE_CACHE_SIZE;
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inode->i_blocks = 0;
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inode->i_mapping->a_ops = &sysfs_aops;
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inode->i_mapping->backing_dev_info = &sysfs_backing_dev_info;
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inode->i_op = &sysfs_inode_operations;
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lockdep_set_class(&inode->i_mutex, &sysfs_inode_imutex_key);
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if (sd->s_iattr) {
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/* sysfs_dirent has non-default attributes
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* get them for the new inode from persistent copy
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* in sysfs_dirent
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*/
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set_inode_attr(inode, sd->s_iattr);
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} else
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set_default_inode_attr(inode, mode);
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}
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return inode;
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}
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int sysfs_create(struct dentry * dentry, int mode, int (*init)(struct inode *))
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{
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int error = 0;
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struct inode * inode = NULL;
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if (dentry) {
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if (!dentry->d_inode) {
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struct sysfs_dirent * sd = dentry->d_fsdata;
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if ((inode = sysfs_new_inode(mode, sd))) {
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if (dentry->d_parent && dentry->d_parent->d_inode) {
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struct inode *p_inode = dentry->d_parent->d_inode;
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p_inode->i_mtime = p_inode->i_ctime = CURRENT_TIME;
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}
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goto Proceed;
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}
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else
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error = -ENOMEM;
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} else
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error = -EEXIST;
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} else
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error = -ENOENT;
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goto Done;
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Proceed:
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if (init)
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error = init(inode);
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if (!error) {
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d_instantiate(dentry, inode);
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if (S_ISDIR(mode))
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dget(dentry); /* pin only directory dentry in core */
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} else
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iput(inode);
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Done:
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return error;
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}
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/*
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* Get the name for corresponding element represented by the given sysfs_dirent
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*/
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const unsigned char * sysfs_get_name(struct sysfs_dirent *sd)
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{
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struct attribute * attr;
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struct bin_attribute * bin_attr;
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struct sysfs_symlink * sl;
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BUG_ON(!sd || !sd->s_element);
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switch (sd->s_type) {
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case SYSFS_DIR:
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/* Always have a dentry so use that */
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return sd->s_dentry->d_name.name;
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case SYSFS_KOBJ_ATTR:
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attr = sd->s_element;
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return attr->name;
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case SYSFS_KOBJ_BIN_ATTR:
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bin_attr = sd->s_element;
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return bin_attr->attr.name;
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case SYSFS_KOBJ_LINK:
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sl = sd->s_element;
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return sl->link_name;
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}
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return NULL;
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}
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/*
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* Unhashes the dentry corresponding to given sysfs_dirent
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* Called with parent inode's i_mutex held.
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*/
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void sysfs_drop_dentry(struct sysfs_dirent * sd, struct dentry * parent)
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{
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struct dentry * dentry = sd->s_dentry;
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if (dentry) {
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spin_lock(&dcache_lock);
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spin_lock(&dentry->d_lock);
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if (!(d_unhashed(dentry) && dentry->d_inode)) {
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dget_locked(dentry);
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__d_drop(dentry);
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spin_unlock(&dentry->d_lock);
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spin_unlock(&dcache_lock);
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simple_unlink(parent->d_inode, dentry);
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} else {
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spin_unlock(&dentry->d_lock);
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spin_unlock(&dcache_lock);
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}
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}
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}
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void sysfs_hash_and_remove(struct dentry * dir, const char * name)
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{
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struct sysfs_dirent * sd;
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struct sysfs_dirent * parent_sd;
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if (!dir)
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return;
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if (dir->d_inode == NULL)
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/* no inode means this hasn't been made visible yet */
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return;
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parent_sd = dir->d_fsdata;
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mutex_lock(&dir->d_inode->i_mutex);
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list_for_each_entry(sd, &parent_sd->s_children, s_sibling) {
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if (!sd->s_element)
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continue;
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if (!strcmp(sysfs_get_name(sd), name)) {
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list_del_init(&sd->s_sibling);
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sysfs_drop_dentry(sd, dir);
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sysfs_put(sd);
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break;
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}
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}
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mutex_unlock(&dir->d_inode->i_mutex);
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}
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