/* * fs/sysfs/inode.c - basic sysfs inode and dentry operations * * Copyright (c) 2001-3 Patrick Mochel * Copyright (c) 2007 SUSE Linux Products GmbH * Copyright (c) 2007 Tejun Heo <teheo@suse.de> * * This file is released under the GPLv2. * * 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 "sysfs.h" extern struct super_block * sysfs_sb; static const struct address_space_operations sysfs_aops = { .readpage = simple_readpage, .write_begin = simple_write_begin, .write_end = simple_write_end, }; static struct backing_dev_info sysfs_backing_dev_info = { .ra_pages = 0, /* No readahead */ .capabilities = BDI_CAP_NO_ACCT_AND_WRITEBACK, }; static const struct inode_operations sysfs_inode_operations ={ .setattr = sysfs_setattr, }; int __init sysfs_inode_init(void) { return bdi_init(&sysfs_backing_dev_info); } 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; iattr->ia_valid &= ~ATTR_SIZE; /* ignore size changes */ 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; static int sysfs_count_nlink(struct sysfs_dirent *sd) { struct sysfs_dirent *child; int nr = 0; for (child = sd->s_dir.children; child; child = child->s_sibling) if (sysfs_type(child) == SYSFS_DIR) nr++; return nr + 2; } static void sysfs_init_inode(struct sysfs_dirent *sd, struct inode *inode) { struct bin_attribute *bin_attr; 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); /* initialize inode according to type */ switch (sysfs_type(sd)) { case SYSFS_DIR: inode->i_op = &sysfs_dir_inode_operations; inode->i_fop = &sysfs_dir_operations; inode->i_nlink = sysfs_count_nlink(sd); break; case SYSFS_KOBJ_ATTR: inode->i_size = PAGE_SIZE; inode->i_fop = &sysfs_file_operations; break; case SYSFS_KOBJ_BIN_ATTR: bin_attr = sd->s_bin_attr.bin_attr; inode->i_size = bin_attr->size; inode->i_fop = &bin_fops; break; case SYSFS_KOBJ_LINK: inode->i_op = &sysfs_symlink_inode_operations; break; default: BUG(); } unlock_new_inode(inode); } /** * 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; } int sysfs_hash_and_remove(struct sysfs_dirent *dir_sd, const char *name) { struct sysfs_addrm_cxt acxt; struct sysfs_dirent *sd; if (!dir_sd) return -ENOENT; sysfs_addrm_start(&acxt, dir_sd); sd = sysfs_find_dirent(dir_sd, name); if (sd) sysfs_remove_one(&acxt, sd); sysfs_addrm_finish(&acxt); if (sd) return 0; else return -ENOENT; }