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/*

 * 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_DIRTY | BDI_CAP_NO_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;

        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;

}