[net-next-2.6.git] / fs / isofs / export.c

/*
 * fs/isofs/export.c
 *
 *  (C) 2004  Paul Serice - The new inode scheme requires switching
 *                          from iget() to iget5_locked() which means
 *                          the NFS export operations have to be hand
 *                          coded because the default routines rely on
 *                          iget().
 *
 * The following files are helpful:
 *
 *     Documentation/filesystems/Exporting
 *     fs/exportfs/expfs.c.
 */

#include "isofs.h"

static struct dentry *
isofs_export_iget(struct super_block *sb,
		  unsigned long block,
		  unsigned long offset,
		  __u32 generation)
{
	struct inode *inode;
	struct dentry *result;
	if (block == 0)
		return ERR_PTR(-ESTALE);
	inode = isofs_iget(sb, block, offset);
	if (IS_ERR(inode))
		return ERR_CAST(inode);
	if (generation && inode->i_generation != generation) {
		iput(inode);
		return ERR_PTR(-ESTALE);
	}
	result = d_alloc_anon(inode);
	if (!result) {
		iput(inode);
		return ERR_PTR(-ENOMEM);
	}
	return result;
}

/* This function is surprisingly simple.  The trick is understanding
 * that "child" is always a directory. So, to find its parent, you
 * simply need to find its ".." entry, normalize its block and offset,
 * and return the underlying inode.  See the comments for
 * isofs_normalize_block_and_offset(). */
static struct dentry *isofs_export_get_parent(struct dentry *child)
{
	unsigned long parent_block = 0;
	unsigned long parent_offset = 0;
	struct inode *child_inode = child->d_inode;
	struct iso_inode_info *e_child_inode = ISOFS_I(child_inode);
	struct inode *parent_inode = NULL;
	struct iso_directory_record *de = NULL;
	struct buffer_head * bh = NULL;
	struct dentry *rv = NULL;

	/* "child" must always be a directory. */
	if (!S_ISDIR(child_inode->i_mode)) {
		printk(KERN_ERR "isofs: isofs_export_get_parent(): "
		       "child is not a directory!\n");
		rv = ERR_PTR(-EACCES);
		goto out;
	}

	/* It is an invariant that the directory offset is zero.  If
	 * it is not zero, it means the directory failed to be
	 * normalized for some reason. */
	if (e_child_inode->i_iget5_offset != 0) {
		printk(KERN_ERR "isofs: isofs_export_get_parent(): "
		       "child directory not normalized!\n");
		rv = ERR_PTR(-EACCES);
		goto out;
	}

	/* The child inode has been normalized such that its
	 * i_iget5_block value points to the "." entry.  Fortunately,
	 * the ".." entry is located in the same block. */
	parent_block = e_child_inode->i_iget5_block;

	/* Get the block in question. */
	bh = sb_bread(child_inode->i_sb, parent_block);
	if (bh == NULL) {
		rv = ERR_PTR(-EACCES);
		goto out;
	}

	/* This is the "." entry. */
	de = (struct iso_directory_record*)bh->b_data;

	/* The ".." entry is always the second entry. */
	parent_offset = (unsigned long)isonum_711(de->length);
	de = (struct iso_directory_record*)(bh->b_data + parent_offset);

	/* Verify it is in fact the ".." entry. */
	if ((isonum_711(de->name_len) != 1) || (de->name[0] != 1)) {
		printk(KERN_ERR "isofs: Unable to find the \"..\" "
		       "directory for NFS.\n");
		rv = ERR_PTR(-EACCES);
		goto out;
	}

	/* Normalize */
	isofs_normalize_block_and_offset(de, &parent_block, &parent_offset);

	/* Get the inode. */
	parent_inode = isofs_iget(child_inode->i_sb,
				  parent_block,
				  parent_offset);
	if (IS_ERR(parent_inode)) {
		rv = ERR_CAST(parent_inode);
		if (rv != ERR_PTR(-ENOMEM))
			rv = ERR_PTR(-EACCES);
		goto out;
	}

	/* Allocate the dentry. */
	rv = d_alloc_anon(parent_inode);
	if (rv == NULL) {
		rv = ERR_PTR(-ENOMEM);
		goto out;
	}

 out:
	if (bh) {
		brelse(bh);
	}
	return rv;
}

static int
isofs_export_encode_fh(struct dentry *dentry,
		       __u32 *fh32,
		       int *max_len,
		       int connectable)
{
	struct inode * inode = dentry->d_inode;
	struct iso_inode_info * ei = ISOFS_I(inode);
	int len = *max_len;
	int type = 1;
	__u16 *fh16 = (__u16*)fh32;

	/*
	 * WARNING: max_len is 5 for NFSv2.  Because of this
	 * limitation, we use the lower 16 bits of fh32[1] to hold the
	 * offset of the inode and the upper 16 bits of fh32[1] to
	 * hold the offset of the parent.
	 */

	if (len < 3 || (connectable && len < 5))
		return 255;

	len = 3;
	fh32[0] = ei->i_iget5_block;
 	fh16[2] = (__u16)ei->i_iget5_offset;  /* fh16 [sic] */
	fh32[2] = inode->i_generation;
	if (connectable && !S_ISDIR(inode->i_mode)) {
		struct inode *parent;
		struct iso_inode_info *eparent;
		spin_lock(&dentry->d_lock);
		parent = dentry->d_parent->d_inode;
		eparent = ISOFS_I(parent);
		fh32[3] = eparent->i_iget5_block;
		fh16[3] = (__u16)eparent->i_iget5_offset;  /* fh16 [sic] */
		fh32[4] = parent->i_generation;
		spin_unlock(&dentry->d_lock);
		len = 5;
		type = 2;
	}
	*max_len = len;
	return type;
}

struct isofs_fid {
	u32 block;
	u16 offset;
	u16 parent_offset;
	u32 generation;
	u32 parent_block;
	u32 parent_generation;
};

static struct dentry *isofs_fh_to_dentry(struct super_block *sb,
	struct fid *fid, int fh_len, int fh_type)
{
	struct isofs_fid *ifid = (struct isofs_fid *)fid;

	if (fh_len < 3 || fh_type > 2)
		return NULL;

	return isofs_export_iget(sb, ifid->block, ifid->offset,
			ifid->generation);
}

static struct dentry *isofs_fh_to_parent(struct super_block *sb,
		struct fid *fid, int fh_len, int fh_type)
{
	struct isofs_fid *ifid = (struct isofs_fid *)fid;

	if (fh_type != 2)
		return NULL;

	return isofs_export_iget(sb,
			fh_len > 2 ? ifid->parent_block : 0,
			ifid->parent_offset,
			fh_len > 4 ? ifid->parent_generation : 0);
}

const struct export_operations isofs_export_ops = {
	.encode_fh	= isofs_export_encode_fh,
	.fh_to_dentry	= isofs_fh_to_dentry,
	.fh_to_parent	= isofs_fh_to_parent,
	.get_parent     = isofs_export_get_parent,
};
Commit	Line	Data
1da177e4 LT	1	/*
	2	* fs/isofs/export.c
	3	*
	4	* (C) 2004 Paul Serice - The new inode scheme requires switching
	5	* from iget() to iget5_locked() which means
	6	* the NFS export operations have to be hand
	7	* coded because the default routines rely on
	8	* iget().
	9	*
	10	* The following files are helpful:
	11	*
	12	* Documentation/filesystems/Exporting
	13	* fs/exportfs/expfs.c.
	14	*/
	15
94f2f715	16	#include "isofs.h"
1da177e4 LT	17
	18	static struct dentry *
	19	isofs_export_iget(struct super_block *sb,
	20	unsigned long block,
	21	unsigned long offset,
	22	__u32 generation)
	23	{
	24	struct inode *inode;
	25	struct dentry *result;
	26	if (block == 0)
	27	return ERR_PTR(-ESTALE);
	28	inode = isofs_iget(sb, block, offset);
c4386c83 DH	29	if (IS_ERR(inode))
	30	return ERR_CAST(inode);
	31	if (generation && inode->i_generation != generation) {
1da177e4 LT	32	iput(inode);
	33	return ERR_PTR(-ESTALE);
	34	}
	35	result = d_alloc_anon(inode);
	36	if (!result) {
	37	iput(inode);
	38	return ERR_PTR(-ENOMEM);
	39	}
	40	return result;
	41	}
	42
1da177e4 LT	43	/* This function is surprisingly simple. The trick is understanding
	44	* that "child" is always a directory. So, to find its parent, you
	45	* simply need to find its ".." entry, normalize its block and offset,
	46	* and return the underlying inode. See the comments for
	47	* isofs_normalize_block_and_offset(). */
	48	static struct dentry isofs_export_get_parent(struct dentry child)
	49	{
	50	unsigned long parent_block = 0;
	51	unsigned long parent_offset = 0;
	52	struct inode *child_inode = child->d_inode;
	53	struct iso_inode_info *e_child_inode = ISOFS_I(child_inode);
	54	struct inode *parent_inode = NULL;
	55	struct iso_directory_record *de = NULL;
	56	struct buffer_head * bh = NULL;
	57	struct dentry *rv = NULL;
	58
	59	/* "child" must always be a directory. */
	60	if (!S_ISDIR(child_inode->i_mode)) {
	61	printk(KERN_ERR "isofs: isofs_export_get_parent(): "
	62	"child is not a directory!\n");
	63	rv = ERR_PTR(-EACCES);
	64	goto out;
	65	}
	66
	67	/* It is an invariant that the directory offset is zero. If
	68	* it is not zero, it means the directory failed to be
	69	* normalized for some reason. */
	70	if (e_child_inode->i_iget5_offset != 0) {
	71	printk(KERN_ERR "isofs: isofs_export_get_parent(): "
	72	"child directory not normalized!\n");
	73	rv = ERR_PTR(-EACCES);
	74	goto out;
	75	}
	76
	77	/* The child inode has been normalized such that its
	78	* i_iget5_block value points to the "." entry. Fortunately,
	79	* the ".." entry is located in the same block. */
	80	parent_block = e_child_inode->i_iget5_block;
	81
	82	/* Get the block in question. */
	83	bh = sb_bread(child_inode->i_sb, parent_block);
	84	if (bh == NULL) {
	85	rv = ERR_PTR(-EACCES);
	86	goto out;
	87	}
	88
	89	/* This is the "." entry. */
	90	de = (struct iso_directory_record*)bh->b_data;
	91
	92	/* The ".." entry is always the second entry. */
	93	parent_offset = (unsigned long)isonum_711(de->length);
	94	de = (struct iso_directory_record*)(bh->b_data + parent_offset);
	95
	96	/* Verify it is in fact the ".." entry. */
	97	if ((isonum_711(de->name_len) != 1) \|\| (de->name[0] != 1)) {
	98	printk(KERN_ERR "isofs: Unable to find the \"..\" "
	99	"directory for NFS.\n");
	100	rv = ERR_PTR(-EACCES);
	101	goto out;
	102	}
	103
	104	/* Normalize */
	105	isofs_normalize_block_and_offset(de, &parent_block, &parent_offset);
	106
107	/* Get the inode. */
108	parent_inode = isofs_iget(child_inode->i_sb,
109	parent_block,
110	parent_offset);
c4386c83 DH	111	if (IS_ERR(parent_inode)) {
	112	rv = ERR_CAST(parent_inode);
	113	if (rv != ERR_PTR(-ENOMEM))
	114	rv = ERR_PTR(-EACCES);
1da177e4 LT	115	goto out;
	116	}
	117
	118	/* Allocate the dentry. */
	119	rv = d_alloc_anon(parent_inode);
	120	if (rv == NULL) {
	121	rv = ERR_PTR(-ENOMEM);
	122	goto out;
	123	}
	124
	125	out:
	126	if (bh) {
	127	brelse(bh);
	128	}
	129	return rv;
	130	}
	131
	132	static int
	133	isofs_export_encode_fh(struct dentry *dentry,
	134	__u32 *fh32,
	135	int *max_len,
	136	int connectable)
	137	{
	138	struct inode * inode = dentry->d_inode;
	139	struct iso_inode_info * ei = ISOFS_I(inode);
	140	int len = *max_len;
	141	int type = 1;
	142	__u16 fh16 = (__u16)fh32;
	143
	144	/*
	145	* WARNING: max_len is 5 for NFSv2. Because of this
	146	* limitation, we use the lower 16 bits of fh32[1] to hold the
	147	* offset of the inode and the upper 16 bits of fh32[1] to
	148	* hold the offset of the parent.
	149	*/
	150
	151	if (len < 3 \|\| (connectable && len < 5))
	152	return 255;
	153
	154	len = 3;
	155	fh32[0] = ei->i_iget5_block;
	156	fh16[2] = (__u16)ei->i_iget5_offset; /* fh16 [sic] */
	157	fh32[2] = inode->i_generation;
	158	if (connectable && !S_ISDIR(inode->i_mode)) {
	159	struct inode *parent;
	160	struct iso_inode_info *eparent;
	161	spin_lock(&dentry->d_lock);
	162	parent = dentry->d_parent->d_inode;
	163	eparent = ISOFS_I(parent);
	164	fh32[3] = eparent->i_iget5_block;
	165	fh16[3] = (__u16)eparent->i_iget5_offset; /* fh16 [sic] */
	166	fh32[4] = parent->i_generation;
	167	spin_unlock(&dentry->d_lock);
	168	len = 5;
	169	type = 2;
	170	}
	171	*max_len = len;
	172	return type;
	173	}
	174
905251a0 CH	175	struct isofs_fid {
	176	u32 block;
	177	u16 offset;
	178	u16 parent_offset;
	179	u32 generation;
	180	u32 parent_block;
	181	u32 parent_generation;
	182	};
1da177e4	183
905251a0 CH	184	static struct dentry isofs_fh_to_dentry(struct super_block sb,
905251a0 CH	185	struct fid *fid, int fh_len, int fh_type)
1da177e4	186	{
905251a0	187	struct isofs_fid ifid = (struct isofs_fid )fid;
1da177e4	188
905251a0	189	if (fh_len < 3 \|\| fh_type > 2)
1da177e4 LT	190	return NULL;
1da177e4 LT	191
905251a0 CH	192	return isofs_export_iget(sb, ifid->block, ifid->offset,
905251a0 CH	193	ifid->generation);
1da177e4 LT	194	}
1da177e4 LT	195
905251a0 CH	196	static struct dentry isofs_fh_to_parent(struct super_block sb,
	197	struct fid *fid, int fh_len, int fh_type)
	198	{
	199	struct isofs_fid ifid = (struct isofs_fid )fid;
	200
	201	if (fh_type != 2)
	202	return NULL;
	203
	204	return isofs_export_iget(sb,
	205	fh_len > 2 ? ifid->parent_block : 0,
	206	ifid->parent_offset,
	207	fh_len > 4 ? ifid->parent_generation : 0);
	208	}
1da177e4	209
39655164	210	const struct export_operations isofs_export_ops = {
1da177e4	211	.encode_fh = isofs_export_encode_fh,
905251a0 CH	212	.fh_to_dentry = isofs_fh_to_dentry,
905251a0 CH	213	.fh_to_parent = isofs_fh_to_parent,
1da177e4 LT	214	.get_parent = isofs_export_get_parent,
1da177e4 LT	215	};