[GitHub/LineageOS/android_kernel_samsung_universal7580.git] / fs / sdcardfs / lookup.c

/*
 * fs/sdcardfs/lookup.c
 *
 * Copyright (c) 2013 Samsung Electronics Co. Ltd
 *   Authors: Daeho Jeong, Woojoong Lee, Seunghwan Hyun,
 *               Sunghwan Yun, Sungjong Seo
 *
 * This program has been developed as a stackable file system based on
 * the WrapFS which written by
 *
 * Copyright (c) 1998-2011 Erez Zadok
 * Copyright (c) 2009     Shrikar Archak
 * Copyright (c) 2003-2011 Stony Brook University
 * Copyright (c) 2003-2011 The Research Foundation of SUNY
 *
 * This file is dual licensed.  It may be redistributed and/or modified
 * under the terms of the Apache 2.0 License OR version 2 of the GNU
 * General Public License.
 */

#include "sdcardfs.h"
#include "linux/delay.h"

/* The dentry cache is just so we have properly sized dentries */
static struct kmem_cache *sdcardfs_dentry_cachep;

int sdcardfs_init_dentry_cache(void)
{
	sdcardfs_dentry_cachep =
		kmem_cache_create("sdcardfs_dentry",
				  sizeof(struct sdcardfs_dentry_info),
				  0, SLAB_RECLAIM_ACCOUNT, NULL);

	return sdcardfs_dentry_cachep ? 0 : -ENOMEM;
}

void sdcardfs_destroy_dentry_cache(void)
{
	kmem_cache_destroy(sdcardfs_dentry_cachep);
}

void free_dentry_private_data(struct dentry *dentry)
{
	if (!dentry || !dentry->d_fsdata)
		return;
	kmem_cache_free(sdcardfs_dentry_cachep, dentry->d_fsdata);
	dentry->d_fsdata = NULL;
}

/* allocate new dentry private data */
int new_dentry_private_data(struct dentry *dentry)
{
	struct sdcardfs_dentry_info *info = SDCARDFS_D(dentry);

	/* use zalloc to init dentry_info.lower_path */
	info = kmem_cache_zalloc(sdcardfs_dentry_cachep, GFP_ATOMIC);
	if (!info)
		return -ENOMEM;

	spin_lock_init(&info->lock);
	dentry->d_fsdata = info;

	return 0;
}

struct inode_data {
	struct inode *lower_inode;
	userid_t id;
};

static int sdcardfs_inode_test(struct inode *inode, void *candidate_data/*void *candidate_lower_inode*/)
{
	struct inode *current_lower_inode = sdcardfs_lower_inode(inode);
	userid_t current_userid = SDCARDFS_I(inode)->data->userid;

	if (current_lower_inode == ((struct inode_data *)candidate_data)->lower_inode &&
			current_userid == ((struct inode_data *)candidate_data)->id)
		return 1; /* found a match */
	else
		return 0; /* no match */
}

static int sdcardfs_inode_set(struct inode *inode, void *lower_inode)
{
	/* we do actual inode initialization in sdcardfs_iget */
	return 0;
}

struct inode *sdcardfs_iget(struct super_block *sb, struct inode *lower_inode, userid_t id)
{
	struct sdcardfs_inode_info *info;
	struct inode_data data;
	struct inode *inode; /* the new inode to return */

	if (!igrab(lower_inode))
		return ERR_PTR(-ESTALE);

	data.id = id;
	data.lower_inode = lower_inode;
	inode = iget5_locked(sb, /* our superblock */
			     /*
			      * hashval: we use inode number, but we can
			      * also use "(unsigned long)lower_inode"
			      * instead.
			      */
			     lower_inode->i_ino, /* hashval */
			     sdcardfs_inode_test, /* inode comparison function */
			     sdcardfs_inode_set, /* inode init function */
			     &data); /* data passed to test+set fxns */
	if (!inode) {
		iput(lower_inode);
		return ERR_PTR(-ENOMEM);
	}
	/* if found a cached inode, then just return it (after iput) */
	if (!(inode->i_state & I_NEW)) {
		iput(lower_inode);
		return inode;
	}

	/* initialize new inode */
	info = SDCARDFS_I(inode);

	inode->i_ino = lower_inode->i_ino;
	sdcardfs_set_lower_inode(inode, lower_inode);

	inode->i_version++;

	/* use different set of inode ops for symlinks & directories */
	if (S_ISDIR(lower_inode->i_mode))
		inode->i_op = &sdcardfs_dir_iops;
	else if (S_ISLNK(lower_inode->i_mode))
		inode->i_op = &sdcardfs_symlink_iops;
	else
		inode->i_op = &sdcardfs_main_iops;

	/* use different set of file ops for directories */
	if (S_ISDIR(lower_inode->i_mode))
		inode->i_fop = &sdcardfs_dir_fops;
	else
		inode->i_fop = &sdcardfs_main_fops;

	inode->i_mapping->a_ops = &sdcardfs_aops;

	inode->i_atime.tv_sec = 0;
	inode->i_atime.tv_nsec = 0;
	inode->i_mtime.tv_sec = 0;
	inode->i_mtime.tv_nsec = 0;
	inode->i_ctime.tv_sec = 0;
	inode->i_ctime.tv_nsec = 0;

	/* properly initialize special inodes */
	if (S_ISBLK(lower_inode->i_mode) || S_ISCHR(lower_inode->i_mode) ||
	    S_ISFIFO(lower_inode->i_mode) || S_ISSOCK(lower_inode->i_mode))
		init_special_inode(inode, lower_inode->i_mode,
				   lower_inode->i_rdev);

	/* all well, copy inode attributes */
	sdcardfs_copy_and_fix_attrs(inode, lower_inode);
	fsstack_copy_inode_size(inode, lower_inode);

	unlock_new_inode(inode);
	return inode;
}

/*
 * Helper interpose routine, called directly by ->lookup to handle
 * spliced dentries.
 */
static struct dentry *__sdcardfs_interpose(struct dentry *dentry,
					 struct super_block *sb,
					 struct path *lower_path,
					 userid_t id)
{
	struct inode *inode;
	struct inode *lower_inode;
	struct super_block *lower_sb;
	struct dentry *ret_dentry;

	lower_inode = lower_path->dentry->d_inode;
	lower_sb = sdcardfs_lower_super(sb);

	/* check that the lower file system didn't cross a mount point */
	if (lower_inode->i_sb != lower_sb) {
		ret_dentry = ERR_PTR(-EXDEV);
		goto out;
	}

	/*
	 * We allocate our new inode below by calling sdcardfs_iget,
	 * which will initialize some of the new inode's fields
	 */

	/* inherit lower inode number for sdcardfs's inode */
	inode = sdcardfs_iget(sb, lower_inode, id);
	if (IS_ERR(inode)) {
		ret_dentry = ERR_CAST(inode);
		goto out;
	}

	ret_dentry = d_splice_alias(inode, dentry);
	dentry = ret_dentry ?: dentry;
	update_derived_permission_lock(dentry);
out:
	return ret_dentry;
}

/*
 * Connect an sdcardfs inode dentry/inode with several lower ones.  This is
 * the classic stackable file system "vnode interposition" action.
 *
 * @dentry: sdcardfs's dentry which interposes on lower one
 * @sb: sdcardfs's super_block
 * @lower_path: the lower path (caller does path_get/put)
 */
int sdcardfs_interpose(struct dentry *dentry, struct super_block *sb,
		     struct path *lower_path, userid_t id)
{
	struct dentry *ret_dentry;

	ret_dentry = __sdcardfs_interpose(dentry, sb, lower_path, id);
	return PTR_ERR(ret_dentry);
}

struct sdcardfs_name_data {
	struct dir_context ctx;
	const struct qstr *to_find;
	char *name;
	bool found;
};

static int sdcardfs_name_match(void *__buf, const char *name, int namelen,
		loff_t offset, u64 ino, unsigned int d_type)
{
	struct sdcardfs_name_data *buf = (struct sdcardfs_name_data *) __buf;
	struct qstr candidate = QSTR_INIT(name, namelen);

	if (qstr_case_eq(buf->to_find, &candidate)) {
		memcpy(buf->name, name, namelen);
		buf->name[namelen] = 0;
		buf->found = true;
		return 1;
	}
	return 0;
}

/*
 * Main driver function for sdcardfs's lookup.
 *
 * Returns: NULL (ok), ERR_PTR if an error occurred.
 * Fills in lower_parent_path with <dentry,mnt> on success.
 */
static struct dentry *__sdcardfs_lookup(struct dentry *dentry,
		unsigned int flags, struct path *lower_parent_path, userid_t id)
{
	int err = 0;
	struct vfsmount *lower_dir_mnt;
	struct dentry *lower_dir_dentry = NULL;
	struct dentry *lower_dentry;
	const struct qstr *name;
	struct path lower_path;
	struct qstr dname;
	struct dentry *ret_dentry = NULL;
	struct sdcardfs_sb_info *sbi;

	sbi = SDCARDFS_SB(dentry->d_sb);
	/* must initialize dentry operations */
	d_set_d_op(dentry, &sdcardfs_ci_dops);

	if (IS_ROOT(dentry))
		goto out;

	name = &dentry->d_name;

	/* now start the actual lookup procedure */
	lower_dir_dentry = lower_parent_path->dentry;
	lower_dir_mnt = lower_parent_path->mnt;

	/* Use vfs_path_lookup to check if the dentry exists or not */
	err = vfs_path_lookup(lower_dir_dentry, lower_dir_mnt, name->name, 0,
				&lower_path);
	/* check for other cases */
	if (err == -ENOENT) {
		struct file *file;
		const struct cred *cred = current_cred();

		struct sdcardfs_name_data buffer = {
			.ctx.actor = sdcardfs_name_match,
			.to_find = name,
			.name = __getname(),
			.found = false,
		};

		if (!buffer.name) {
			err = -ENOMEM;
			goto out;
		}
		file = dentry_open(lower_parent_path, O_RDONLY, cred);
		if (IS_ERR(file)) {
			err = PTR_ERR(file);
			goto put_name;
		}
		err = iterate_dir(file, &buffer.ctx);
		fput(file);
		if (err)
			goto put_name;

		if (buffer.found)
			err = vfs_path_lookup(lower_dir_dentry,
						lower_dir_mnt,
						buffer.name, 0,
						&lower_path);
		else
			err = -ENOENT;
put_name:
		__putname(buffer.name);
	}

	/* no error: handle positive dentries */
	if (!err) {
		/* check if the dentry is an obb dentry
		 * if true, the lower_inode must be replaced with
		 * the inode of the graft path
		 */

		if (need_graft_path(dentry)) {

			/* setup_obb_dentry()
			 * The lower_path will be stored to the dentry's orig_path
			 * and the base obbpath will be copyed to the lower_path variable.
			 * if an error returned, there's no change in the lower_path
			 * returns: -ERRNO if error (0: no error)
			 */
			err = setup_obb_dentry(dentry, &lower_path);

			if (err) {
				/* if the sbi->obbpath is not available, we can optionally
				 * setup the lower_path with its orig_path.
				 * but, the current implementation just returns an error
				 * because the sdcard daemon also regards this case as
				 * a lookup fail.
				 */
				pr_info("sdcardfs: base obbpath is not available\n");
				sdcardfs_put_reset_orig_path(dentry);
				goto out;
			}
		}

		sdcardfs_set_lower_path(dentry, &lower_path);
		ret_dentry =
			__sdcardfs_interpose(dentry, dentry->d_sb, &lower_path, id);
		if (IS_ERR(ret_dentry)) {
			err = PTR_ERR(ret_dentry);
			 /* path_put underlying path on error */
			sdcardfs_put_reset_lower_path(dentry);
		}
		goto out;
	}

	/*
	 * We don't consider ENOENT an error, and we want to return a
	 * negative dentry.
	 */
	if (err && err != -ENOENT)
		goto out;

	/* instatiate a new negative dentry */
	dname.name = name->name;
	dname.len = name->len;
	dname.hash = full_name_hash(dname.name, dname.len);
	lower_dentry = d_lookup(lower_dir_dentry, &dname);
	if (lower_dentry)
		goto setup_lower;

	lower_dentry = d_alloc(lower_dir_dentry, &dname);
	if (!lower_dentry) {
		err = -ENOMEM;
		goto out;
	}
	d_add(lower_dentry, NULL); /* instantiate and hash */

setup_lower:
	lower_path.dentry = lower_dentry;
	lower_path.mnt = mntget(lower_dir_mnt);
	sdcardfs_set_lower_path(dentry, &lower_path);

	/*
	 * If the intent is to create a file, then don't return an error, so
	 * the VFS will continue the process of making this negative dentry
	 * into a positive one.
	 */
	if (flags & (LOOKUP_CREATE|LOOKUP_RENAME_TARGET))
		err = 0;

out:
	if (err)
		return ERR_PTR(err);
	return ret_dentry;
}

/*
 * 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)) {
		ret = ERR_PTR(-EACCES);
		goto out_err;
	}

	/* save current_cred and override it */
	OVERRIDE_CRED_PTR(SDCARDFS_SB(dir->i_sb), saved_cred, SDCARDFS_I(dir));

	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,
				SDCARDFS_I(dir)->data->userid);
	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 derived permission */
		get_derived_permission(parent, dentry);
		fixup_tmp_permissions(dentry->d_inode);
		fixup_lower_ownership(dentry, dentry->d_name.name);
	}
	/* 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;
}
Commit	Line	Data
ee184c81 DC	1	/*
	2	* fs/sdcardfs/lookup.c
	3	*
	4	* Copyright (c) 2013 Samsung Electronics Co. Ltd
	5	* Authors: Daeho Jeong, Woojoong Lee, Seunghwan Hyun,
	6	* Sunghwan Yun, Sungjong Seo
	7	*
	8	* This program has been developed as a stackable file system based on
	9	* the WrapFS which written by
	10	*
	11	* Copyright (c) 1998-2011 Erez Zadok
	12	* Copyright (c) 2009 Shrikar Archak
	13	* Copyright (c) 2003-2011 Stony Brook University
	14	* Copyright (c) 2003-2011 The Research Foundation of SUNY
	15	*
	16	* This file is dual licensed. It may be redistributed and/or modified
	17	* under the terms of the Apache 2.0 License OR version 2 of the GNU
	18	* General Public License.
	19	*/
	20
	21	#include "sdcardfs.h"
	22	#include "linux/delay.h"
	23
	24	/* The dentry cache is just so we have properly sized dentries */
	25	static struct kmem_cache *sdcardfs_dentry_cachep;
	26
	27	int sdcardfs_init_dentry_cache(void)
	28	{
	29	sdcardfs_dentry_cachep =
	30	kmem_cache_create("sdcardfs_dentry",
	31	sizeof(struct sdcardfs_dentry_info),
	32	0, SLAB_RECLAIM_ACCOUNT, NULL);
	33
	34	return sdcardfs_dentry_cachep ? 0 : -ENOMEM;
	35	}
	36
	37	void sdcardfs_destroy_dentry_cache(void)
	38	{
fb692c2e	39	kmem_cache_destroy(sdcardfs_dentry_cachep);
ee184c81 DC	40	}
	41
	42	void free_dentry_private_data(struct dentry *dentry)
	43	{
	44	if (!dentry \|\| !dentry->d_fsdata)
	45	return;
	46	kmem_cache_free(sdcardfs_dentry_cachep, dentry->d_fsdata);
	47	dentry->d_fsdata = NULL;
	48	}
	49
	50	/* allocate new dentry private data */
	51	int new_dentry_private_data(struct dentry *dentry)
	52	{
	53	struct sdcardfs_dentry_info *info = SDCARDFS_D(dentry);
	54
	55	/* use zalloc to init dentry_info.lower_path */
	56	info = kmem_cache_zalloc(sdcardfs_dentry_cachep, GFP_ATOMIC);
	57	if (!info)
	58	return -ENOMEM;
	59
	60	spin_lock_init(&info->lock);
	61	dentry->d_fsdata = info;
	62
	63	return 0;
	64	}
	65
3ebb8b99 DR	66	struct inode_data {
	67	struct inode *lower_inode;
	68	userid_t id;
	69	};
	70
	71	static int sdcardfs_inode_test(struct inode inode, void candidate_data/void candidate_lower_inode*/)
ee184c81 DC	72	{
ee184c81 DC	73	struct inode *current_lower_inode = sdcardfs_lower_inode(inode);
2b8e1225	74	userid_t current_userid = SDCARDFS_I(inode)->data->userid;
e1211368	75
3ebb8b99 DR	76	if (current_lower_inode == ((struct inode_data *)candidate_data)->lower_inode &&
3ebb8b99 DR	77	current_userid == ((struct inode_data *)candidate_data)->id)
ee184c81 DC	78	return 1; /* found a match */
	79	else
	80	return 0; /* no match */
	81	}
	82
	83	static int sdcardfs_inode_set(struct inode inode, void lower_inode)
	84	{
	85	/* we do actual inode initialization in sdcardfs_iget */
	86	return 0;
	87	}
	88
3ebb8b99	89	struct inode sdcardfs_iget(struct super_block sb, struct inode *lower_inode, userid_t id)
ee184c81 DC	90	{
ee184c81 DC	91	struct sdcardfs_inode_info *info;
3ebb8b99	92	struct inode_data data;
ee184c81	93	struct inode inode; / the new inode to return */
df69e20e DR	94
	95	if (!igrab(lower_inode))
	96	return ERR_PTR(-ESTALE);
ee184c81	97
3ebb8b99 DR	98	data.id = id;
3ebb8b99 DR	99	data.lower_inode = lower_inode;
ee184c81 DC	100	inode = iget5_locked(sb, /* our superblock */
	101	/*
	102	* hashval: we use inode number, but we can
	103	* also use "(unsigned long)lower_inode"
	104	* instead.
	105	*/
	106	lower_inode->i_ino, /* hashval */
e1211368	107	sdcardfs_inode_test, /* inode comparison function */
ee184c81	108	sdcardfs_inode_set, /* inode init function */
3ebb8b99	109	&data); /* data passed to test+set fxns */
ee184c81	110	if (!inode) {
ee184c81	111	iput(lower_inode);
df69e20e	112	return ERR_PTR(-ENOMEM);
ee184c81	113	}
df69e20e DR	114	/* if found a cached inode, then just return it (after iput) */
	115	if (!(inode->i_state & I_NEW)) {
	116	iput(lower_inode);
ee184c81	117	return inode;
df69e20e	118	}
ee184c81 DC	119
	120	/* initialize new inode */
	121	info = SDCARDFS_I(inode);
	122
	123	inode->i_ino = lower_inode->i_ino;
ee184c81 DC	124	sdcardfs_set_lower_inode(inode, lower_inode);
	125
	126	inode->i_version++;
	127
	128	/* use different set of inode ops for symlinks & directories */
	129	if (S_ISDIR(lower_inode->i_mode))
	130	inode->i_op = &sdcardfs_dir_iops;
	131	else if (S_ISLNK(lower_inode->i_mode))
	132	inode->i_op = &sdcardfs_symlink_iops;
	133	else
	134	inode->i_op = &sdcardfs_main_iops;
	135
	136	/* use different set of file ops for directories */
	137	if (S_ISDIR(lower_inode->i_mode))
	138	inode->i_fop = &sdcardfs_dir_fops;
	139	else
	140	inode->i_fop = &sdcardfs_main_fops;
	141
	142	inode->i_mapping->a_ops = &sdcardfs_aops;
	143
	144	inode->i_atime.tv_sec = 0;
	145	inode->i_atime.tv_nsec = 0;
	146	inode->i_mtime.tv_sec = 0;
	147	inode->i_mtime.tv_nsec = 0;
	148	inode->i_ctime.tv_sec = 0;
	149	inode->i_ctime.tv_nsec = 0;
	150
	151	/* properly initialize special inodes */
	152	if (S_ISBLK(lower_inode->i_mode) \|\| S_ISCHR(lower_inode->i_mode) \|\|
	153	S_ISFIFO(lower_inode->i_mode) \|\| S_ISSOCK(lower_inode->i_mode))
	154	init_special_inode(inode, lower_inode->i_mode,
	155	lower_inode->i_rdev);
	156
	157	/* all well, copy inode attributes */
3ebb8b99	158	sdcardfs_copy_and_fix_attrs(inode, lower_inode);
ee184c81 DC	159	fsstack_copy_inode_size(inode, lower_inode);
ee184c81 DC	160
ee184c81 DC	161	unlock_new_inode(inode);
	162	return inode;
	163	}
	164
	165	/*
4bf924f0 DR	166	* Helper interpose routine, called directly by ->lookup to handle
4bf924f0 DR	167	* spliced dentries.
ee184c81	168	*/
4bf924f0 DR	169	static struct dentry __sdcardfs_interpose(struct dentry dentry,
	170	struct super_block *sb,
	171	struct path *lower_path,
	172	userid_t id)
ee184c81	173	{
ee184c81 DC	174	struct inode *inode;
	175	struct inode *lower_inode;
	176	struct super_block *lower_sb;
4bf924f0	177	struct dentry *ret_dentry;
ee184c81 DC	178
	179	lower_inode = lower_path->dentry->d_inode;
	180	lower_sb = sdcardfs_lower_super(sb);
	181
	182	/* check that the lower file system didn't cross a mount point */
	183	if (lower_inode->i_sb != lower_sb) {
4bf924f0	184	ret_dentry = ERR_PTR(-EXDEV);
ee184c81 DC	185	goto out;
	186	}
	187
	188	/*
	189	* We allocate our new inode below by calling sdcardfs_iget,
	190	* which will initialize some of the new inode's fields
	191	*/
	192
	193	/* inherit lower inode number for sdcardfs's inode */
3ebb8b99	194	inode = sdcardfs_iget(sb, lower_inode, id);
ee184c81	195	if (IS_ERR(inode)) {
4bf924f0	196	ret_dentry = ERR_CAST(inode);
ee184c81 DC	197	goto out;
	198	}
	199
4bf924f0 DR	200	ret_dentry = d_splice_alias(inode, dentry);
4bf924f0 DR	201	dentry = ret_dentry ?: dentry;
3ebb8b99	202	update_derived_permission_lock(dentry);
ee184c81	203	out:
4bf924f0 DR	204	return ret_dentry;
	205	}
	206
	207	/*
	208	* Connect an sdcardfs inode dentry/inode with several lower ones. This is
	209	* the classic stackable file system "vnode interposition" action.
	210	*
	211	* @dentry: sdcardfs's dentry which interposes on lower one
	212	* @sb: sdcardfs's super_block
	213	* @lower_path: the lower path (caller does path_get/put)
	214	*/
	215	int sdcardfs_interpose(struct dentry dentry, struct super_block sb,
	216	struct path *lower_path, userid_t id)
	217	{
	218	struct dentry *ret_dentry;
	219
	220	ret_dentry = __sdcardfs_interpose(dentry, sb, lower_path, id);
	221	return PTR_ERR(ret_dentry);
ee184c81 DC	222	}
ee184c81 DC	223
d03cf4c9 DR	224	struct sdcardfs_name_data {
	225	struct dir_context ctx;
	226	const struct qstr *to_find;
	227	char *name;
	228	bool found;
	229	};
	230
	231	static int sdcardfs_name_match(void __buf, const char name, int namelen,
	232	loff_t offset, u64 ino, unsigned int d_type)
	233	{
	234	struct sdcardfs_name_data buf = (struct sdcardfs_name_data ) __buf;
	235	struct qstr candidate = QSTR_INIT(name, namelen);
	236
	237	if (qstr_case_eq(buf->to_find, &candidate)) {
	238	memcpy(buf->name, name, namelen);
	239	buf->name[namelen] = 0;
	240	buf->found = true;
	241	return 1;
	242	}
	243	return 0;
	244	}
	245
ee184c81 DC	246	/*
	247	* Main driver function for sdcardfs's lookup.
	248	*
	249	* Returns: NULL (ok), ERR_PTR if an error occurred.
	250	* Fills in lower_parent_path with <dentry,mnt> on success.
	251	*/
	252	static struct dentry __sdcardfs_lookup(struct dentry dentry,
3ebb8b99	253	unsigned int flags, struct path *lower_parent_path, userid_t id)
ee184c81 DC	254	{
	255	int err = 0;
	256	struct vfsmount *lower_dir_mnt;
	257	struct dentry *lower_dir_dentry = NULL;
	258	struct dentry *lower_dentry;
0bd58959	259	const struct qstr *name;
ee184c81	260	struct path lower_path;
2578b04a	261	struct qstr dname;
4bf924f0	262	struct dentry *ret_dentry = NULL;
ee184c81 DC	263	struct sdcardfs_sb_info *sbi;
	264
	265	sbi = SDCARDFS_SB(dentry->d_sb);
	266	/* must initialize dentry operations */
	267	d_set_d_op(dentry, &sdcardfs_ci_dops);
	268
	269	if (IS_ROOT(dentry))
	270	goto out;
	271
0bd58959	272	name = &dentry->d_name;
ee184c81 DC	273
	274	/* now start the actual lookup procedure */
	275	lower_dir_dentry = lower_parent_path->dentry;
	276	lower_dir_mnt = lower_parent_path->mnt;
	277
	278	/* Use vfs_path_lookup to check if the dentry exists or not */
0bd58959	279	err = vfs_path_lookup(lower_dir_dentry, lower_dir_mnt, name->name, 0,
542a676e	280	&lower_path);
d6783077 DR	281	/* check for other cases */
d6783077 DR	282	if (err == -ENOENT) {
d03cf4c9 DR	283	struct file *file;
	284	const struct cred *cred = current_cred();
	285
	286	struct sdcardfs_name_data buffer = {
	287	.ctx.actor = sdcardfs_name_match,
	288	.to_find = name,
	289	.name = __getname(),
	290	.found = false,
	291	};
	292
	293	if (!buffer.name) {
	294	err = -ENOMEM;
	295	goto out;
	296	}
	297	file = dentry_open(lower_parent_path, O_RDONLY, cred);
	298	if (IS_ERR(file)) {
	299	err = PTR_ERR(file);
	300	goto put_name;
d6783077	301	}
d03cf4c9 DR	302	err = iterate_dir(file, &buffer.ctx);
	303	fput(file);
	304	if (err)
	305	goto put_name;
	306
	307	if (buffer.found)
d6783077 DR	308	err = vfs_path_lookup(lower_dir_dentry,
d6783077 DR	309	lower_dir_mnt,
d03cf4c9	310	buffer.name, 0,
d6783077	311	&lower_path);
d03cf4c9 DR	312	else
	313	err = -ENOENT;
	314	put_name:
	315	__putname(buffer.name);
d6783077	316	}
ee184c81 DC	317
	318	/* no error: handle positive dentries */
	319	if (!err) {
	320	/* check if the dentry is an obb dentry
	321	* if true, the lower_inode must be replaced with
e1211368 DR	322	* the inode of the graft path
e1211368 DR	323	*/
ee184c81	324
e1211368	325	if (need_graft_path(dentry)) {
ee184c81 DC	326
ee184c81 DC	327	/* setup_obb_dentry()
e1211368	328	* The lower_path will be stored to the dentry's orig_path
ee184c81 DC	329	* and the base obbpath will be copyed to the lower_path variable.
ee184c81 DC	330	* if an error returned, there's no change in the lower_path
e1211368 DR	331	* returns: -ERRNO if error (0: no error)
e1211368 DR	332	*/
542a676e	333	err = setup_obb_dentry(dentry, &lower_path);
ee184c81	334
e1211368	335	if (err) {
ee184c81 DC	336	/* if the sbi->obbpath is not available, we can optionally
	337	* setup the lower_path with its orig_path.
	338	* but, the current implementation just returns an error
	339	* because the sdcard daemon also regards this case as
e1211368 DR	340	* a lookup fail.
e1211368 DR	341	*/
43602c05	342	pr_info("sdcardfs: base obbpath is not available\n");
ee184c81 DC	343	sdcardfs_put_reset_orig_path(dentry);
	344	goto out;
	345	}
	346	}
	347
542a676e	348	sdcardfs_set_lower_path(dentry, &lower_path);
4bf924f0 DR	349	ret_dentry =
	350	__sdcardfs_interpose(dentry, dentry->d_sb, &lower_path, id);
	351	if (IS_ERR(ret_dentry)) {
	352	err = PTR_ERR(ret_dentry);
	353	/* path_put underlying path on error */
ee184c81	354	sdcardfs_put_reset_lower_path(dentry);
4bf924f0	355	}
ee184c81 DC	356	goto out;
	357	}
	358
	359	/*
	360	* We don't consider ENOENT an error, and we want to return a
	361	* negative dentry.
	362	*/
	363	if (err && err != -ENOENT)
	364	goto out;
	365
	366	/* instatiate a new negative dentry */
2578b04a DR	367	dname.name = name->name;
	368	dname.len = name->len;
	369	dname.hash = full_name_hash(dname.name, dname.len);
	370	lower_dentry = d_lookup(lower_dir_dentry, &dname);
0d2128be DR	371	if (lower_dentry)
	372	goto setup_lower;
	373
	374	lower_dentry = d_alloc(lower_dir_dentry, &dname);
ee184c81	375	if (!lower_dentry) {
0d2128be	376	err = -ENOMEM;
ee184c81 DC	377	goto out;
ee184c81 DC	378	}
0d2128be	379	d_add(lower_dentry, NULL); /* instantiate and hash */
ee184c81	380
0d2128be	381	setup_lower:
ee184c81 DC	382	lower_path.dentry = lower_dentry;
	383	lower_path.mnt = mntget(lower_dir_mnt);
	384	sdcardfs_set_lower_path(dentry, &lower_path);
	385
	386	/*
	387	* If the intent is to create a file, then don't return an error, so
	388	* the VFS will continue the process of making this negative dentry
	389	* into a positive one.
	390	*/
542a676e	391	if (flags & (LOOKUP_CREATE\|LOOKUP_RENAME_TARGET))
ee184c81 DC	392	err = 0;
	393
	394	out:
4bf924f0 DR	395	if (err)
	396	return ERR_PTR(err);
	397	return ret_dentry;
ee184c81 DC	398	}
	399
	400	/*
	401	* On success:
e1211368	402	* fills dentry object appropriate values and returns NULL.
ee184c81	403	* On fail (== error)
e1211368	404	* returns error ptr
ee184c81 DC	405	*
	406	* @dir : Parent inode. It is locked (dir->i_mutex)
	407	* @dentry : Target dentry to lookup. we should set each of fields.
	408	* (dentry->d_name is initialized already)
	409	* @nd : nameidata of parent inode
	410	*/
	411	struct dentry sdcardfs_lookup(struct inode dir, struct dentry *dentry,
542a676e	412	unsigned int flags)
ee184c81 DC	413	{
	414	struct dentry ret = NULL, parent;
	415	struct path lower_parent_path;
	416	int err = 0;
ee184c81 DC	417	const struct cred *saved_cred = NULL;
	418
	419	parent = dget_parent(dentry);
	420
e1211368	421	if (!check_caller_access_to_name(parent->d_inode, &dentry->d_name)) {
ee184c81	422	ret = ERR_PTR(-EACCES);
ee184c81	423	goto out_err;
e1211368	424	}
ee184c81 DC	425
ee184c81 DC	426	/* save current_cred and override it */
f4d33b9a	427	OVERRIDE_CRED_PTR(SDCARDFS_SB(dir->i_sb), saved_cred, SDCARDFS_I(dir));
ee184c81 DC	428
	429	sdcardfs_get_lower_path(parent, &lower_parent_path);
	430
	431	/* allocate dentry private data. We free it in ->d_release */
	432	err = new_dentry_private_data(dentry);
	433	if (err) {
	434	ret = ERR_PTR(err);
	435	goto out;
	436	}
	437
2b8e1225 DR	438	ret = __sdcardfs_lookup(dentry, flags, &lower_parent_path,
2b8e1225 DR	439	SDCARDFS_I(dir)->data->userid);
ee184c81	440	if (IS_ERR(ret))
ee184c81	441	goto out;
ee184c81 DC	442	if (ret)
	443	dentry = ret;
	444	if (dentry->d_inode) {
	445	fsstack_copy_attr_times(dentry->d_inode,
	446	sdcardfs_lower_inode(dentry->d_inode));
4e9ba27b	447	/* get derived permission */
ee184c81	448	get_derived_permission(parent, dentry);
a50d4516	449	fixup_tmp_permissions(dentry->d_inode);
f4d33b9a	450	fixup_lower_ownership(dentry, dentry->d_name.name);
ee184c81 DC	451	}
	452	/* update parent directory's atime */
	453	fsstack_copy_attr_atime(parent->d_inode,
	454	sdcardfs_lower_inode(parent->d_inode));
	455
	456	out:
	457	sdcardfs_put_lower_path(parent, &lower_parent_path);
	458	REVERT_CRED(saved_cred);
	459	out_err:
	460	dput(parent);
	461	return ret;
	462	}