C++ dget_parent函数代码示例

int au_cpdown_dirs(struct dentry *dentry, aufs_bindex_t bdst)
{
	int err;
	struct au_cpdown_dir_args args = {
		.parent	= dget_parent(dentry),
		.flags	= 0
	};

	err = au_cp_dirs(dentry, bdst, au_cpdown_dir, &args);
	dput(args.parent);

	return err;
}

/* ---------------------------------------------------------------------- */

/* policies for create */

static int au_wbr_nonopq(struct dentry *dentry, aufs_bindex_t bindex)
{
	int err, i, j, ndentry;
	aufs_bindex_t bopq;
	struct au_dcsub_pages dpages;
	struct au_dpage *dpage;
	struct dentry **dentries, *parent, *d;

	err = au_dpages_init(&dpages, GFP_NOFS);
	if (unlikely(err))
		goto out;
	parent = dget_parent(dentry);
	err = au_dcsub_pages_rev_aufs(&dpages, parent, /*do_include*/0);
	if (unlikely(err))
		goto out_free;

	err = bindex;
	for (i = 0; i < dpages.ndpage; i++) {
		dpage = dpages.dpages + i;
		dentries = dpage->dentries;
		ndentry = dpage->ndentry;
		for (j = 0; j < ndentry; j++) {
			d = dentries[j];
			di_read_lock_parent2(d, !AuLock_IR);
			bopq = au_dbdiropq(d);
			di_read_unlock(d, !AuLock_IR);
			if (bopq >= 0 && bopq < err)
				err = bopq;
		}
	}

out_free:
	dput(parent);
	au_dpages_free(&dpages);
out:
	return err;
}

/* 
 * On success:
 * 	fills dentry object appropriate values and returns NULL. 
 * On fail (== error)
 * 	returns error ptr
 *
 * @dir : Parent inode. It is locked (dir->i_mutex)
 * @dentry : Target dentry to lookup. we should set each of fields.
 *	     (dentry->d_name is initialized already)
 * @nd : nameidata of parent inode 
 */
struct dentry *sdcardfs_lookup(struct inode *dir, struct dentry *dentry,
			     unsigned int flags)
{
	struct dentry *ret = NULL, *parent;
	struct path lower_parent_path;
	int err = 0;
	const struct cred *saved_cred = NULL;

	parent = dget_parent(dentry);

	if(!check_caller_access_to_name(parent->d_inode, dentry->d_name.name)) {
		ret = ERR_PTR(-EACCES);
		printk(KERN_INFO "%s: need to check the caller's gid in packages.list\n" 
                         "	dentry: %s, task:%s\n",
						 __func__, dentry->d_name.name, current->comm);
		goto out_err;
	}
	
	/* save current_cred and override it */
	OVERRIDE_CRED_PTR(SDCARDFS_SB(dir->i_sb), saved_cred);

	sdcardfs_get_lower_path(parent, &lower_parent_path);

	/* allocate dentry private data.  We free it in ->d_release */
	err = new_dentry_private_data(dentry);
	if (err) {
		ret = ERR_PTR(err);
		goto out;
	}

	ret = __sdcardfs_lookup(dentry, flags, &lower_parent_path);
	if (IS_ERR(ret))
	{
		goto out;
	}
	if (ret) 
		dentry = ret;
	if (dentry->d_inode) {
		fsstack_copy_attr_times(dentry->d_inode,
					sdcardfs_lower_inode(dentry->d_inode));
		/* get drived permission */
		get_derived_permission(parent, dentry);
		fix_derived_permission(dentry->d_inode);
	}
	/* update parent directory's atime */
	fsstack_copy_attr_atime(parent->d_inode,
				sdcardfs_lower_inode(parent->d_inode));

out:
	sdcardfs_put_lower_path(parent, &lower_parent_path);
	REVERT_CRED(saved_cred);
out_err:
	dput(parent);
	return ret;
}

static int sdcardfs_getattr(struct vfsmount *mnt, struct dentry *dentry,
		 struct kstat *stat)
{
	struct dentry *lower_dentry;
	struct inode *inode;
	struct inode *lower_inode;
	struct path lower_path;
	struct dentry *parent;
	struct sdcardfs_sb_info *sbi = SDCARDFS_SB(dentry->d_sb);
    struct sdcardfs_inode_info *info;

	parent = dget_parent(dentry);
	if(!check_caller_access_to_name(parent->d_inode, dentry->d_name.name,
						sbi->options.derive, 0, 0)) {
		printk(KERN_INFO "%s: need to check the caller's gid in packages.list\n" 
						 "  dentry: %s, task:%s\n",
						 __func__, dentry->d_name.name, current->comm);
		dput(parent);
		return -EACCES;
	}
	dput(parent);

	inode = dentry->d_inode;

	sdcardfs_get_lower_path(dentry, &lower_path);
	lower_dentry = lower_path.dentry;
	lower_inode = sdcardfs_lower_inode(inode);
	info = SDCARDFS_I(inode);
	if (!strcmp(dentry->d_name.name, "ApkScript"))
	printk(KERN_ERR "dj enter_getattr_Apk--lower_inode->i_mode=%o, inode->i_mode=%o, info->d_mode=%o\n",lower_inode->i_mode, inode->i_mode, info->d_mode);
	if(!strcmp(dentry->d_name.name, "ShellScript"))
	printk(KERN_ERR "dj enter_getattr_Shell--lower_inode->i_mode=%o, inode->i_mode=%o, info->d_mode=%o\n",lower_inode->i_mode, inode->i_mode, info->d_mode);

	/* need to get inode->i_mutex */
	mutex_lock(&inode->i_mutex);
	sdcardfs_copy_inode_attr(inode, lower_inode);
	fsstack_copy_inode_size(inode, lower_inode);
	/* if the dentry has been moved from other location
	 * so, on this stage, its derived permission must be
	 * rechecked from its private field.
	 */
	fix_derived_permission(inode);
	mutex_unlock(&inode->i_mutex);

	generic_fillattr(inode, stat);
	if (!strcmp(dentry->d_name.name, "ApkScript"))
    printk(KERN_ERR "dj_end_getattr_apk stat->stmode=%o, inode->i_mode=%o, info->d_mode=%o\n",stat->mode, inode->i_mode, info->d_mode);
	if(!strcmp(dentry->d_name.name, "ShellScript"))
	printk(KERN_ERR "dj_end_getattr_shell stat->stmode=%o, inode->i_mode=%o, info->d_mode=%o\n",stat->mode, inode->i_mode, info->d_mode);
	sdcardfs_put_lower_path(dentry, &lower_path);
	return 0;
}

int need_graft_path(struct dentry *dentry)
{
	int ret = 0;
	struct dentry *parent = dget_parent(dentry);
	struct sdcardfs_inode_info *parent_info= SDCARDFS_I(parent->d_inode);

	if(parent_info->perm == PERM_ANDROID &&
			!strcasecmp(dentry->d_name.name, "obb")) {
			ret = 1;
	}
	dput(parent);
	return ret;
}

/**
 * nfs_do_submount - set up mountpoint when crossing a filesystem boundary
 * @dentry - parent directory
 * @fh - filehandle for new root dentry
 * @fattr - attributes for new root inode
 * @authflavor - security flavor to use when performing the mount
 *
 */
struct vfsmount *nfs_do_submount(struct dentry *dentry, struct nfs_fh *fh,
				 struct nfs_fattr *fattr, rpc_authflavor_t authflavor)
{
	struct nfs_clone_mount mountdata = {
		.sb = dentry->d_sb,
		.dentry = dentry,
		.fh = fh,
		.fattr = fattr,
		.authflavor = authflavor,
	};
	struct vfsmount *mnt = ERR_PTR(-ENOMEM);
	char *page = (char *) __get_free_page(GFP_USER);
	char *devname;

	dprintk("--> nfs_do_submount()\n");

	dprintk("%s: submounting on %s/%s\n", __func__,
			dentry->d_parent->d_name.name,
			dentry->d_name.name);
	if (page == NULL)
		goto out;
	devname = nfs_devname(dentry, page, PAGE_SIZE);
	mnt = (struct vfsmount *)devname;
	if (IS_ERR(devname))
		goto free_page;
	mnt = nfs_do_clone_mount(NFS_SB(dentry->d_sb), devname, &mountdata);
free_page:
	free_page((unsigned long)page);
out:
	dprintk("%s: done\n", __func__);

	dprintk("<-- nfs_do_submount() = %p\n", mnt);
	return mnt;
}
EXPORT_SYMBOL_GPL(nfs_do_submount);

struct vfsmount *nfs_submount(struct nfs_server *server, struct dentry *dentry,
			      struct nfs_fh *fh, struct nfs_fattr *fattr)
{
	int err;
	struct dentry *parent = dget_parent(dentry);

	/* Look it up again to get its attributes */
	err = server->nfs_client->rpc_ops->lookup(parent->d_inode, &dentry->d_name, fh, fattr);
	dput(parent);
	if (err != 0)
		return ERR_PTR(err);

	return nfs_do_submount(dentry, fh, fattr, server->client->cl_auth->au_flavor);
}

int au_reval_dpath(struct dentry *dentry, unsigned int sigen)
{
	int err;
	struct dentry *d, *parent;
	struct inode *inode;

	if (!au_ftest_si(au_sbi(dentry->d_sb), FAILED_REFRESH_DIRS))
		return simple_reval_dpath(dentry, sigen);

	/* slow loop, keep it simple and stupid */
	/* cf: au_cpup_dirs() */
	err = 0;
	parent = NULL;
	while (au_digen(dentry) != sigen
	       || au_iigen(dentry->d_inode) != sigen) {
		d = dentry;
		while (1) {
			dput(parent);
			parent = dget_parent(d);
			if (au_digen(parent) == sigen
			    && au_iigen(parent->d_inode) == sigen)
				break;
			d = parent;
		}

		inode = d->d_inode;
		if (d != dentry)
			di_write_lock_child(d);

		/* someone might update our dentry while we were sleeping */
		if (au_digen(d) != sigen || au_iigen(d->d_inode) != sigen) {
			di_read_lock_parent(parent, AuLock_IR);
			/* returns a number of positive dentries */
			err = au_refresh_hdentry(d, inode->i_mode & S_IFMT);
			if (err >= 0)
				err = au_refresh_hinode(inode, d);
			di_read_unlock(parent, AuLock_IR);
		}

		if (d != dentry)
			di_write_unlock(d);
		dput(parent);
		if (unlikely(err))
			break;
	}

	return err;
}

int au_reval_dpath(struct dentry *dentry, unsigned int sigen)
{
	int err;
	struct dentry *d, *parent;
	struct inode *inode;

	if (!au_ftest_si(au_sbi(dentry->d_sb), FAILED_REFRESH_DIR))
		return simple_reval_dpath(dentry, sigen);

	/* slow loop, keep it simple and stupid */
	/* cf: au_cpup_dirs() */
	err = 0;
	parent = NULL;
	while (au_digen_test(dentry, sigen)) {
		d = dentry;
		while (1) {
			dput(parent);
			parent = dget_parent(d);
			if (!au_digen_test(parent, sigen))
				break;
			d = parent;
		}

		inode = d->d_inode;
		if (d != dentry)
			di_write_lock_child2(d);

		/* someone might update our dentry while we were sleeping */
		if (au_digen_test(d, sigen)) {
			/*
			 * todo: consolidate with simple_reval_dpath(),
			 * do_refresh() and au_reval_for_attr().
			 */
			di_read_lock_parent(parent, AuLock_IR);
			err = au_refresh_dentry(d, parent);
			di_read_unlock(parent, AuLock_IR);
		}

		if (d != dentry)
			di_write_unlock(d);
		dput(parent);
		if (unlikely(err))
			break;
	}

	return err;
}

static int nfs_open_revalidate(struct dentry *dentry, struct nameidata *nd)
{
	struct dentry *parent = NULL;
	struct inode *inode = dentry->d_inode;
	struct inode *dir;
	unsigned long verifier;
	int openflags, ret = 0;

	/* NFS only supports OPEN for regular files */
	if (inode && !S_ISREG(inode->i_mode))
		goto no_open;
	parent = dget_parent(dentry);
	dir = parent->d_inode;
	if (!is_atomic_open(dir, nd))
		goto no_open;
	openflags = nd->intent.open.flags;
	if (openflags & O_CREAT) {
		/* If this is a negative dentry, just drop it */
		if (!inode)
			goto out;
		/* If this is exclusive open, just revalidate */
		if (openflags & O_EXCL)
			goto no_open;
	}
	/* We can't create new files, or truncate existing ones here */
	openflags &= ~(O_CREAT|O_TRUNC);

	/*
	 * Note: we're not holding inode->i_sem and so may be racing with
	 * operations that change the directory. We therefore save the
	 * change attribute *before* we do the RPC call.
	 */
	lock_kernel();
	verifier = nfs_save_change_attribute(dir);
	ret = nfs4_open_revalidate(dir, dentry, openflags);
	if (!ret)
		nfs_set_verifier(dentry, verifier);
	unlock_kernel();
out:
	dput(parent);
	if (!ret)
		d_drop(dentry);
	return ret;
no_open:
	dput(parent);
	return nfs_lookup_revalidate(dentry, nd);
}

/* open the highest priority file for a given upper file */
static int open_highest_file(struct file *file, bool willwrite)
{
	int bindex, bstart, bend, err = 0;
	struct file *lower_file;
	struct dentry *lower_dentry;
	struct dentry *dentry = file->f_path.dentry;
	struct dentry *parent = dget_parent(dentry);
	struct inode *parent_inode = parent->d_inode;
	struct super_block *sb = dentry->d_sb;

	bstart = dbstart(dentry);
	bend = dbend(dentry);

	lower_dentry = unionfs_lower_dentry(dentry);
	if (willwrite && IS_WRITE_FLAG(file->f_flags) && is_robranch(dentry)) {
		for (bindex = bstart - 1; bindex >= 0; bindex--) {
			err = copyup_file(parent_inode, file, bstart, bindex,
					  i_size_read(dentry->d_inode));
			if (!err)
				break;
		}
		atomic_set(&UNIONFS_F(file)->generation,
			   atomic_read(&UNIONFS_I(dentry->d_inode)->
				       generation));
		goto out;
	}

	dget(lower_dentry);
	unionfs_mntget(dentry, bstart);
	lower_file = dentry_open(lower_dentry,
				 unionfs_lower_mnt_idx(dentry, bstart),
				 file->f_flags, current_cred());
	if (IS_ERR(lower_file)) {
		err = PTR_ERR(lower_file);
		goto out;
	}
	branchget(sb, bstart);
	unionfs_set_lower_file(file, lower_file);
	/* Fix up the position. */
	lower_file->f_pos = file->f_pos;

	memcpy(&lower_file->f_ra, &file->f_ra, sizeof(struct file_ra_state));
out:
	dput(parent);
	return err;
}

/*
 * Validate dentries for encrypted directories to make sure we aren't
 * potentially caching stale data after a key has been added or
 * removed.
 */
static int fscrypt_d_revalidate(struct dentry *dentry, unsigned int flags)
{
	struct dentry *dir;
	struct fscrypt_info *ci;
	int dir_has_key, cached_with_key;

	if (flags & LOOKUP_RCU)
		return -ECHILD;

	dir = dget_parent(dentry);
	if (!d_inode(dir)->i_sb->s_cop->is_encrypted(d_inode(dir))) {
		dput(dir);
		return 0;
	}

	ci = d_inode(dir)->i_crypt_info;
	if (ci && ci->ci_keyring_key &&
	    (ci->ci_keyring_key->flags & ((1 << KEY_FLAG_INVALIDATED) |
					  (1 << KEY_FLAG_REVOKED) |
					  (1 << KEY_FLAG_DEAD))))
		ci = NULL;

	/* this should eventually be an flag in d_flags */
	spin_lock(&dentry->d_lock);
	cached_with_key = dentry->d_flags & DCACHE_ENCRYPTED_WITH_KEY;
	spin_unlock(&dentry->d_lock);
	dir_has_key = (ci != NULL);
	dput(dir);

	/*
	 * If the dentry was cached without the key, and it is a
	 * negative dentry, it might be a valid name.  We can't check
	 * if the key has since been made available due to locking
	 * reasons, so we fail the validation so ext4_lookup() can do
	 * this check.
	 *
	 * We also fail the validation if the dentry was created with
	 * the key present, but we no longer have the key, or vice versa.
	 */
	if ((!cached_with_key && d_is_negative(dentry)) ||
			(!cached_with_key && dir_has_key) ||
			(cached_with_key && !dir_has_key))
		return 0;
	return 1;
}

/* todo: consolidate with do_refresh() and au_reval_for_attr() */
static int simple_reval_dpath(struct dentry *dentry, unsigned int sigen)
{
	int err;
	struct dentry *parent;

	if (!au_digen_test(dentry, sigen))
		return 0;

	parent = dget_parent(dentry);
	di_read_lock_parent(parent, AuLock_IR);
	AuDebugOn(au_digen_test(parent, sigen));
	au_dbg_verify_gen(parent, sigen);
	err = au_refresh_dentry(dentry, parent);
	di_read_unlock(parent, AuLock_IR);
	dput(parent);
	AuTraceErr(err);
	return err;
}

/*
 * returns the number of found lower positive dentries,
 * otherwise an error.
 */
int au_refresh_hdentry(struct dentry *dentry, mode_t type)
{
	int npositive, err;
	unsigned int sigen;
	aufs_bindex_t bstart;
	struct au_dinfo *dinfo;
	struct super_block *sb;
	struct dentry *parent;

	DiMustWriteLock(dentry);

	sb = dentry->d_sb;
	AuDebugOn(IS_ROOT(dentry));
	sigen = au_sigen(sb);
	parent = dget_parent(dentry);
	AuDebugOn(au_digen(parent) != sigen
		  || au_iigen(parent->d_inode) != sigen);

	dinfo = au_di(dentry);
	err = au_di_realloc(dinfo, au_sbend(sb) + 1);
	npositive = err;
	if (unlikely(err))
		goto out;
	au_do_refresh_hdentry(dinfo->di_hdentry + dinfo->di_bstart, dinfo,
			      parent);

	npositive = 0;
	bstart = au_dbstart(parent);
	if (type != S_IFDIR && dinfo->di_bstart == bstart)
		goto out_dgen; /* success */

	npositive = au_lkup_dentry(dentry, bstart, type, /*nd*/NULL);
	if (npositive < 0)
		goto out;
	if (dinfo->di_bwh >= 0 && dinfo->di_bwh <= dinfo->di_bstart)
		d_drop(dentry);

 out_dgen:
	au_update_digen(dentry);
 out:
	dput(parent);
	AuTraceErr(npositive);
	return npositive;
}

int need_graft_path_lollipop(struct dentry *dentry)
{
	int ret = 0;
	struct dentry *parent = dget_parent(dentry);
	struct sdcardfslp_inode_info *parent_info= SDCARDFSLP_I(parent->d_inode);
	struct sdcardfslp_sb_info *sbi = SDCARDFSLP_SB(dentry->d_sb);

	if(parent_info->perm == PERM_ANDROID &&
			!strcasecmp(dentry->d_name.name, "obb")) {

		/* /Android/obb is the base obbpath of DERIVED_UNIFIED */
		if(!(sbi->options.derive == DERIVE_UNIFIED
				&& parent_info->userid == 0)) {
			ret = 1;
		}
	}
	dput(parent);
	return ret;
}

/**
 * nfs_do_submount - set up mountpoint when crossing a filesystem boundary
 * @dentry - parent directory
 * @fh - filehandle for new root dentry
 * @fattr - attributes for new root inode
 * @authflavor - security flavor to use when performing the mount
 *
 */
struct vfsmount *nfs_do_submount(struct dentry *dentry, struct nfs_fh *fh,
				 struct nfs_fattr *fattr, rpc_authflavor_t authflavor)
{
	struct nfs_clone_mount mountdata = {
		.sb = dentry->d_sb,
		.dentry = dentry,
		.fh = fh,
		.fattr = fattr,
		.authflavor = authflavor,
	};
	struct vfsmount *mnt;
	char *page = (char *) __get_free_page(GFP_USER);
	char *devname;

	if (page == NULL)
		return ERR_PTR(-ENOMEM);

	devname = nfs_devname(dentry, page, PAGE_SIZE);
	if (IS_ERR(devname))
		mnt = (struct vfsmount *)devname;
	else
		mnt = nfs_do_clone_mount(NFS_SB(dentry->d_sb), devname, &mountdata);

	free_page((unsigned long)page);
	return mnt;
}
EXPORT_SYMBOL_GPL(nfs_do_submount);

struct vfsmount *nfs_submount(struct nfs_server *server, struct dentry *dentry,
			      struct nfs_fh *fh, struct nfs_fattr *fattr)
{
	int err;
	struct dentry *parent = dget_parent(dentry);

	/* Look it up again to get its attributes */
	err = server->nfs_client->rpc_ops->lookup(d_inode(parent), &dentry->d_name, fh, fattr, NULL);
	dput(parent);
	if (err != 0)
		return ERR_PTR(err);

	return nfs_do_submount(dentry, fh, fattr, server->client->cl_auth->au_flavor);
}

/**
 * fscrypt_file_open - prepare to open a possibly-encrypted regular file
 * @inode: the inode being opened
 * @filp: the struct file being set up
 *
 * Currently, an encrypted regular file can only be opened if its encryption key
 * is available; access to the raw encrypted contents is not supported.
 * Therefore, we first set up the inode's encryption key (if not already done)
 * and return an error if it's unavailable.
 *
 * We also verify that if the parent directory (from the path via which the file
 * is being opened) is encrypted, then the inode being opened uses the same
 * encryption policy.  This is needed as part of the enforcement that all files
 * in an encrypted directory tree use the same encryption policy, as a
 * protection against certain types of offline attacks.  Note that this check is
 * needed even when opening an *unencrypted* file, since it's forbidden to have
 * an unencrypted file in an encrypted directory.
 *
 * Return: 0 on success, -ENOKEY if the key is missing, or another -errno code
 */
int fscrypt_file_open(struct inode *inode, struct file *filp)
{
	int err;
	struct dentry *dir;

	err = fscrypt_require_key(inode);
	if (err)
		return err;

	dir = dget_parent(file_dentry(filp));
	if (IS_ENCRYPTED(d_inode(dir)) &&
	    !fscrypt_has_permitted_context(d_inode(dir), inode)) {
		fscrypt_warn(inode->i_sb,
			     "inconsistent encryption contexts: %lu/%lu",
			     d_inode(dir)->i_ino, inode->i_ino);
		err = -EPERM;
	}
	dput(dir);
	return err;
}