/* * 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 "sysfs.h" extern struct super_block * sysfs_sb; static 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 struct inode_operations sysfs_inode_operations ={ .setattr = sysfs_setattr, }; 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 = kmalloc(sizeof(struct iattr), GFP_KERNEL); if (!sd_iattr) return -ENOMEM; /* assign default attributes */ memset(sd_iattr, 0, sizeof(struct iattr)); 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; } struct inode * sysfs_new_inode(mode_t mode, struct sysfs_dirent * sd) { struct inode * inode = new_inode(sysfs_sb); if (inode) { inode->i_blksize = PAGE_CACHE_SIZE; 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; 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, mode); } return inode; } int sysfs_create(struct dentry * dentry, int mode, int (*init)(struct inode *)) { int error = 0; struct inode * inode = NULL; if (dentry) { if (!dentry->d_inode) { struct sysfs_dirent * sd = dentry->d_fsdata; if ((inode = sysfs_new_inode(mode, sd))) { 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; } goto Proceed; } else error = -ENOMEM; } else error = -EEXIST; } else error = -ENOENT; goto Done; Proceed: if (init) error = init(inode); if (!error) { d_instantiate(dentry, inode); if (S_ISDIR(mode)) dget(dentry); /* pin only directory dentry in core */ } else iput(inode); Done: return error; } /* * Get the name for corresponding element represented by the given sysfs_dirent */ const unsigned char * sysfs_get_name(struct sysfs_dirent *sd) { struct attribute * attr; struct bin_attribute * bin_attr; struct sysfs_symlink * sl; if (!sd || !sd->s_element) BUG(); switch (sd->s_type) { case SYSFS_DIR: /* Always have a dentry so use that */ return sd->s_dentry->d_name.name; case SYSFS_KOBJ_ATTR: attr = sd->s_element; return attr->name; case SYSFS_KOBJ_BIN_ATTR: bin_attr = sd->s_element; return bin_attr->attr.name; case SYSFS_KOBJ_LINK: sl = sd->s_element; return sl->link_name; } return NULL; } /* * Unhashes the dentry corresponding to given sysfs_dirent * Called with parent inode's i_sem held. */ void sysfs_drop_dentry(struct sysfs_dirent * sd, struct dentry * parent) { struct dentry * dentry = sd->s_dentry; if (dentry) { spin_lock(&dcache_lock); spin_lock(&dentry->d_lock); if (!(d_unhashed(dentry) && dentry->d_inode)) { dget_locked(dentry); __d_drop(dentry); spin_unlock(&dentry->d_lock); spin_unlock(&dcache_lock); simple_unlink(parent->d_inode, dentry); } else { spin_unlock(&dentry->d_lock); spin_unlock(&dcache_lock); } } } void sysfs_hash_and_remove(struct dentry * dir, const char * name) { struct sysfs_dirent * sd; struct sysfs_dirent * parent_sd = dir->d_fsdata; if (dir->d_inode == NULL) /* no inode means this hasn't been made visible yet */ return; down(&dir->d_inode->i_sem); list_for_each_entry(sd, &parent_sd->s_children, s_sibling) { if (!sd->s_element) continue; if (!strcmp(sysfs_get_name(sd), name)) { list_del_init(&sd->s_sibling); sysfs_drop_dentry(sd, dir); sysfs_put(sd); break; } } up(&dir->d_inode->i_sem); }