| /* |
| * inode.c - basic inode and dentry operations. |
| * |
| * sysfs is Copyright (c) 2001-3 Patrick Mochel |
| * |
| * Please see Documentation/filesystems/sysfs.txt for more information. |
| */ |
| |
| #undef DEBUG |
| |
| #include <linux/pagemap.h> |
| #include <linux/namei.h> |
| #include <linux/backing-dev.h> |
| #include <linux/capability.h> |
| #include <linux/errno.h> |
| #include <linux/sched.h> |
| #include <asm/semaphore.h> |
| #include "sysfs.h" |
| |
| extern struct super_block * sysfs_sb; |
| |
| static const struct address_space_operations sysfs_aops = { |
| .readpage = simple_readpage, |
| .prepare_write = simple_prepare_write, |
| .commit_write = simple_commit_write |
| }; |
| |
| static struct backing_dev_info sysfs_backing_dev_info = { |
| .ra_pages = 0, /* No readahead */ |
| .capabilities = BDI_CAP_NO_ACCT_DIRTY | BDI_CAP_NO_WRITEBACK, |
| }; |
| |
| static const struct inode_operations sysfs_inode_operations ={ |
| .setattr = sysfs_setattr, |
| }; |
| |
| void sysfs_delete_inode(struct inode *inode) |
| { |
| /* Free the shadowed directory inode operations */ |
| if (sysfs_is_shadowed_inode(inode)) { |
| kfree(inode->i_op); |
| inode->i_op = NULL; |
| } |
| return generic_delete_inode(inode); |
| } |
| |
| int sysfs_setattr(struct dentry * dentry, struct iattr * iattr) |
| { |
| struct inode * inode = dentry->d_inode; |
| struct sysfs_dirent * sd = dentry->d_fsdata; |
| struct iattr * sd_iattr; |
| unsigned int ia_valid = iattr->ia_valid; |
| int error; |
| |
| if (!sd) |
| return -EINVAL; |
| |
| sd_iattr = sd->s_iattr; |
| |
| error = inode_change_ok(inode, iattr); |
| if (error) |
| return error; |
| |
| error = inode_setattr(inode, iattr); |
| if (error) |
| return error; |
| |
| if (!sd_iattr) { |
| /* setting attributes for the first time, allocate now */ |
| sd_iattr = kzalloc(sizeof(struct iattr), GFP_KERNEL); |
| if (!sd_iattr) |
| return -ENOMEM; |
| /* assign default attributes */ |
| sd_iattr->ia_mode = sd->s_mode; |
| sd_iattr->ia_uid = 0; |
| sd_iattr->ia_gid = 0; |
| sd_iattr->ia_atime = sd_iattr->ia_mtime = sd_iattr->ia_ctime = CURRENT_TIME; |
| sd->s_iattr = sd_iattr; |
| } |
| |
| /* attributes were changed atleast once in past */ |
| |
| if (ia_valid & ATTR_UID) |
| sd_iattr->ia_uid = iattr->ia_uid; |
| if (ia_valid & ATTR_GID) |
| sd_iattr->ia_gid = iattr->ia_gid; |
| if (ia_valid & ATTR_ATIME) |
| sd_iattr->ia_atime = timespec_trunc(iattr->ia_atime, |
| inode->i_sb->s_time_gran); |
| if (ia_valid & ATTR_MTIME) |
| sd_iattr->ia_mtime = timespec_trunc(iattr->ia_mtime, |
| inode->i_sb->s_time_gran); |
| if (ia_valid & ATTR_CTIME) |
| sd_iattr->ia_ctime = timespec_trunc(iattr->ia_ctime, |
| inode->i_sb->s_time_gran); |
| if (ia_valid & ATTR_MODE) { |
| umode_t mode = iattr->ia_mode; |
| |
| if (!in_group_p(inode->i_gid) && !capable(CAP_FSETID)) |
| mode &= ~S_ISGID; |
| sd_iattr->ia_mode = sd->s_mode = mode; |
| } |
| |
| return error; |
| } |
| |
| static inline void set_default_inode_attr(struct inode * inode, mode_t mode) |
| { |
| inode->i_mode = mode; |
| inode->i_uid = 0; |
| inode->i_gid = 0; |
| inode->i_atime = inode->i_mtime = inode->i_ctime = CURRENT_TIME; |
| } |
| |
| static inline void set_inode_attr(struct inode * inode, struct iattr * iattr) |
| { |
| inode->i_mode = iattr->ia_mode; |
| inode->i_uid = iattr->ia_uid; |
| inode->i_gid = iattr->ia_gid; |
| inode->i_atime = iattr->ia_atime; |
| inode->i_mtime = iattr->ia_mtime; |
| inode->i_ctime = iattr->ia_ctime; |
| } |
| |
| |
| /* |
| * sysfs has a different i_mutex lock order behavior for i_mutex than 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. |
| */ |
| static struct lock_class_key sysfs_inode_imutex_key; |
| |
| void sysfs_init_inode(struct sysfs_dirent *sd, struct inode *inode) |
| { |
| inode->i_blocks = 0; |
| inode->i_mapping->a_ops = &sysfs_aops; |
| inode->i_mapping->backing_dev_info = &sysfs_backing_dev_info; |
| inode->i_op = &sysfs_inode_operations; |
| inode->i_ino = sd->s_ino; |
| lockdep_set_class(&inode->i_mutex, &sysfs_inode_imutex_key); |
| |
| if (sd->s_iattr) { |
| /* sysfs_dirent has non-default attributes |
| * get them for the new inode from persistent copy |
| * in sysfs_dirent |
| */ |
| set_inode_attr(inode, sd->s_iattr); |
| } else |
| set_default_inode_attr(inode, sd->s_mode); |
| } |
| |
| /** |
| * sysfs_get_inode - get inode for sysfs_dirent |
| * @sd: sysfs_dirent to allocate inode for |
| * |
| * Get inode for @sd. If such inode doesn't exist, a new inode |
| * is allocated and basics are initialized. New inode is |
| * returned locked. |
| * |
| * LOCKING: |
| * Kernel thread context (may sleep). |
| * |
| * RETURNS: |
| * Pointer to allocated inode on success, NULL on failure. |
| */ |
| struct inode * sysfs_get_inode(struct sysfs_dirent *sd) |
| { |
| struct inode *inode; |
| |
| inode = iget_locked(sysfs_sb, sd->s_ino); |
| if (inode && (inode->i_state & I_NEW)) |
| sysfs_init_inode(sd, inode); |
| |
| return inode; |
| } |
| |
| /** |
| * sysfs_instantiate - instantiate dentry |
| * @dentry: dentry to be instantiated |
| * @inode: inode associated with @sd |
| * |
| * Unlock @inode if locked and instantiate @dentry with @inode. |
| * |
| * LOCKING: |
| * None. |
| */ |
| void sysfs_instantiate(struct dentry *dentry, struct inode *inode) |
| { |
| BUG_ON(!dentry || dentry->d_inode); |
| |
| if (inode->i_state & I_NEW) { |
| unlock_new_inode(inode); |
| |
| if (dentry->d_parent && dentry->d_parent->d_inode) { |
| struct inode *p_inode = dentry->d_parent->d_inode; |
| p_inode->i_mtime = p_inode->i_ctime = CURRENT_TIME; |
| } |
| } |
| |
| d_instantiate(dentry, inode); |
| } |
| |
| /** |
| * sysfs_drop_dentry - drop dentry for the specified sysfs_dirent |
| * @sd: target sysfs_dirent |
| * |
| * Drop dentry for @sd. @sd must have been unlinked from its |
| * parent on entry to this function such that it can't be looked |
| * up anymore. |
| * |
| * @sd->s_dentry which is protected with sysfs_assoc_lock points |
| * to the currently associated dentry but we're not holding a |
| * reference to it and racing with dput(). Grab dcache_lock and |
| * verify dentry before dropping it. If @sd->s_dentry is NULL or |
| * dput() beats us, no need to bother. |
| */ |
| void sysfs_drop_dentry(struct sysfs_dirent *sd) |
| { |
| struct dentry *dentry = NULL; |
| struct timespec curtime; |
| struct inode *inode; |
| |
| /* We're not holding a reference to ->s_dentry dentry but the |
| * field will stay valid as long as sysfs_assoc_lock is held. |
| */ |
| spin_lock(&sysfs_assoc_lock); |
| spin_lock(&dcache_lock); |
| |
| /* drop dentry if it's there and dput() didn't kill it yet */ |
| if (sd->s_dentry && sd->s_dentry->d_inode) { |
| dentry = dget_locked(sd->s_dentry); |
| spin_lock(&dentry->d_lock); |
| __d_drop(dentry); |
| spin_unlock(&dentry->d_lock); |
| } |
| |
| spin_unlock(&dcache_lock); |
| spin_unlock(&sysfs_assoc_lock); |
| |
| dput(dentry); |
| /* XXX: unpin if directory, this will go away soon */ |
| if (sysfs_type(sd) == SYSFS_DIR) |
| dput(dentry); |
| |
| /* adjust nlink and update timestamp */ |
| curtime = CURRENT_TIME; |
| |
| inode = ilookup(sysfs_sb, sd->s_ino); |
| if (inode) { |
| mutex_lock(&inode->i_mutex); |
| |
| inode->i_ctime = curtime; |
| drop_nlink(inode); |
| if (sysfs_type(sd) == SYSFS_DIR) |
| drop_nlink(inode); |
| |
| mutex_unlock(&inode->i_mutex); |
| iput(inode); |
| } |
| |
| /* adjust nlink and udpate timestamp of the parent */ |
| inode = ilookup(sysfs_sb, sd->s_parent->s_ino); |
| if (inode) { |
| mutex_lock(&inode->i_mutex); |
| |
| inode->i_ctime = inode->i_mtime = curtime; |
| if (sysfs_type(sd) == SYSFS_DIR) |
| drop_nlink(inode); |
| |
| mutex_unlock(&inode->i_mutex); |
| iput(inode); |
| } |
| } |
| |
| int sysfs_hash_and_remove(struct sysfs_dirent *dir_sd, const char *name) |
| { |
| struct sysfs_dirent **pos, *sd; |
| int found = 0; |
| |
| if (!dir_sd) |
| return -ENOENT; |
| |
| mutex_lock(&sysfs_mutex); |
| |
| for (pos = &dir_sd->s_children; *pos; pos = &(*pos)->s_sibling) { |
| sd = *pos; |
| |
| if (!sysfs_type(sd)) |
| continue; |
| if (!strcmp(sd->s_name, name)) { |
| sd->s_flags |= SYSFS_FLAG_REMOVED; |
| *pos = sd->s_sibling; |
| sd->s_sibling = NULL; |
| found = 1; |
| break; |
| } |
| } |
| |
| mutex_unlock(&sysfs_mutex); |
| |
| if (!found) |
| return -ENOENT; |
| |
| sysfs_drop_dentry(sd); |
| sysfs_deactivate(sd); |
| sysfs_put(sd); |
| |
| return 0; |
| } |