dir.c

linux 内核源代码

		if (gfs2_check_dirent(dent, offset, size, len, 0))
			goto consist_inode;
	} while(1);

	switch(ret) {
	case 0:
		return NULL;
	case 1:
		return dent;
	case 2:
		return prev ? prev : dent;
	default:
		BUG_ON(ret > 0);
		return ERR_PTR(ret);
	}

consist_inode:
	gfs2_consist_inode(GFS2_I(inode));
	return ERR_PTR(-EIO);
}


/**
 * dirent_first - Return the first dirent
 * @dip: the directory
 * @bh: The buffer
 * @dent: Pointer to list of dirents
 *
 * return first dirent whether bh points to leaf or stuffed dinode
 *
 * Returns: IS_LEAF, IS_DINODE, or -errno
 */

static int dirent_first(struct gfs2_inode *dip, struct buffer_head *bh,
			struct gfs2_dirent **dent)
{
	struct gfs2_meta_header *h = (struct gfs2_meta_header *)bh->b_data;

	if (be32_to_cpu(h->mh_type) == GFS2_METATYPE_LF) {
		if (gfs2_meta_check(GFS2_SB(&dip->i_inode), bh))
			return -EIO;
		*dent = (struct gfs2_dirent *)(bh->b_data +
					       sizeof(struct gfs2_leaf));
		return IS_LEAF;
	} else {
		if (gfs2_metatype_check(GFS2_SB(&dip->i_inode), bh, GFS2_METATYPE_DI))
			return -EIO;
		*dent = (struct gfs2_dirent *)(bh->b_data +
					       sizeof(struct gfs2_dinode));
		return IS_DINODE;
	}
}

static int dirent_check_reclen(struct gfs2_inode *dip,
			       const struct gfs2_dirent *d, const void *end_p)
{
	const void *ptr = d;
	u16 rec_len = be16_to_cpu(d->de_rec_len);

	if (unlikely(rec_len < sizeof(struct gfs2_dirent)))
		goto broken;
	ptr += rec_len;
	if (ptr < end_p)
		return rec_len;
	if (ptr == end_p)
		return -ENOENT;
broken:
	gfs2_consist_inode(dip);
	return -EIO;
}

/**
 * dirent_next - Next dirent
 * @dip: the directory
 * @bh: The buffer
 * @dent: Pointer to list of dirents
 *
 * Returns: 0 on success, error code otherwise
 */

static int dirent_next(struct gfs2_inode *dip, struct buffer_head *bh,
		       struct gfs2_dirent **dent)
{
	struct gfs2_dirent *cur = *dent, *tmp;
	char *bh_end = bh->b_data + bh->b_size;
	int ret;

	ret = dirent_check_reclen(dip, cur, bh_end);
	if (ret < 0)
		return ret;

	tmp = (void *)cur + ret;
	ret = dirent_check_reclen(dip, tmp, bh_end);
	if (ret == -EIO)
		return ret;

        /* Only the first dent could ever have de_inum.no_addr == 0 */
	if (gfs2_dirent_sentinel(tmp)) {
		gfs2_consist_inode(dip);
		return -EIO;
	}

	*dent = tmp;
	return 0;
}

/**
 * dirent_del - Delete a dirent
 * @dip: The GFS2 inode
 * @bh: The buffer
 * @prev: The previous dirent
 * @cur: The current dirent
 *
 */

static void dirent_del(struct gfs2_inode *dip, struct buffer_head *bh,
		       struct gfs2_dirent *prev, struct gfs2_dirent *cur)
{
	u16 cur_rec_len, prev_rec_len;

	if (gfs2_dirent_sentinel(cur)) {
		gfs2_consist_inode(dip);
		return;
	}

	gfs2_trans_add_bh(dip->i_gl, bh, 1);

	/* If there is no prev entry, this is the first entry in the block.
	   The de_rec_len is already as big as it needs to be.  Just zero
	   out the inode number and return.  */

	if (!prev) {
		cur->de_inum.no_addr = 0;
		cur->de_inum.no_formal_ino = 0;
		return;
	}

	/*  Combine this dentry with the previous one.  */

	prev_rec_len = be16_to_cpu(prev->de_rec_len);
	cur_rec_len = be16_to_cpu(cur->de_rec_len);

	if ((char *)prev + prev_rec_len != (char *)cur)
		gfs2_consist_inode(dip);
	if ((char *)cur + cur_rec_len > bh->b_data + bh->b_size)
		gfs2_consist_inode(dip);

	prev_rec_len += cur_rec_len;
	prev->de_rec_len = cpu_to_be16(prev_rec_len);
}

/*
 * Takes a dent from which to grab space as an argument. Returns the
 * newly created dent.
 */
static struct gfs2_dirent *gfs2_init_dirent(struct inode *inode,
					    struct gfs2_dirent *dent,
					    const struct qstr *name,
					    struct buffer_head *bh)
{
	struct gfs2_inode *ip = GFS2_I(inode);
	struct gfs2_dirent *ndent;
	unsigned offset = 0, totlen;

	if (!gfs2_dirent_sentinel(dent))
		offset = GFS2_DIRENT_SIZE(be16_to_cpu(dent->de_name_len));
	totlen = be16_to_cpu(dent->de_rec_len);
	BUG_ON(offset + name->len > totlen);
	gfs2_trans_add_bh(ip->i_gl, bh, 1);
	ndent = (struct gfs2_dirent *)((char *)dent + offset);
	dent->de_rec_len = cpu_to_be16(offset);
	gfs2_qstr2dirent(name, totlen - offset, ndent);
	return ndent;
}

static struct gfs2_dirent *gfs2_dirent_alloc(struct inode *inode,
					     struct buffer_head *bh,
					     const struct qstr *name)
{
	struct gfs2_dirent *dent;
	dent = gfs2_dirent_scan(inode, bh->b_data, bh->b_size,
				gfs2_dirent_find_space, name, NULL);
	if (!dent || IS_ERR(dent))
		return dent;
	return gfs2_init_dirent(inode, dent, name, bh);
}

static int get_leaf(struct gfs2_inode *dip, u64 leaf_no,
		    struct buffer_head **bhp)
{
	int error;

	error = gfs2_meta_read(dip->i_gl, leaf_no, DIO_WAIT, bhp);
	if (!error && gfs2_metatype_check(GFS2_SB(&dip->i_inode), *bhp, GFS2_METATYPE_LF)) {
		/* printk(KERN_INFO "block num=%llu\n", leaf_no); */
		error = -EIO;
	}

	return error;
}

/**
 * get_leaf_nr - Get a leaf number associated with the index
 * @dip: The GFS2 inode
 * @index:
 * @leaf_out:
 *
 * Returns: 0 on success, error code otherwise
 */

static int get_leaf_nr(struct gfs2_inode *dip, u32 index,
		       u64 *leaf_out)
{
	__be64 leaf_no;
	int error;

	error = gfs2_dir_read_data(dip, (char *)&leaf_no,
				    index * sizeof(__be64),
				    sizeof(__be64), 0);
	if (error != sizeof(u64))
		return (error < 0) ? error : -EIO;

	*leaf_out = be64_to_cpu(leaf_no);

	return 0;
}

static int get_first_leaf(struct gfs2_inode *dip, u32 index,
			  struct buffer_head **bh_out)
{
	u64 leaf_no;
	int error;

	error = get_leaf_nr(dip, index, &leaf_no);
	if (!error)
		error = get_leaf(dip, leaf_no, bh_out);

	return error;
}

static struct gfs2_dirent *gfs2_dirent_search(struct inode *inode,
					      const struct qstr *name,
					      gfs2_dscan_t scan,
					      struct buffer_head **pbh)
{
	struct buffer_head *bh;
	struct gfs2_dirent *dent;
	struct gfs2_inode *ip = GFS2_I(inode);
	int error;

	if (ip->i_di.di_flags & GFS2_DIF_EXHASH) {
		struct gfs2_leaf *leaf;
		unsigned hsize = 1 << ip->i_di.di_depth;
		unsigned index;
		u64 ln;
		if (hsize * sizeof(u64) != ip->i_di.di_size) {
			gfs2_consist_inode(ip);
			return ERR_PTR(-EIO);
		}

		index = name->hash >> (32 - ip->i_di.di_depth);
		error = get_first_leaf(ip, index, &bh);
		if (error)
			return ERR_PTR(error);
		do {
			dent = gfs2_dirent_scan(inode, bh->b_data, bh->b_size,
						scan, name, NULL);
			if (dent)
				goto got_dent;
			leaf = (struct gfs2_leaf *)bh->b_data;
			ln = be64_to_cpu(leaf->lf_next);
			brelse(bh);
			if (!ln)
				break;

			error = get_leaf(ip, ln, &bh);
		} while(!error);

		return error ? ERR_PTR(error) : NULL;
	}


	error = gfs2_meta_inode_buffer(ip, &bh);
	if (error)
		return ERR_PTR(error);
	dent = gfs2_dirent_scan(inode, bh->b_data, bh->b_size, scan, name, NULL);
got_dent:
	if (unlikely(dent == NULL || IS_ERR(dent))) {
		brelse(bh);
		bh = NULL;
	}
	*pbh = bh;
	return dent;
}

static struct gfs2_leaf *new_leaf(struct inode *inode, struct buffer_head **pbh, u16 depth)
{
	struct gfs2_inode *ip = GFS2_I(inode);
	u64 bn = gfs2_alloc_meta(ip);
	struct buffer_head *bh = gfs2_meta_new(ip->i_gl, bn);
	struct gfs2_leaf *leaf;
	struct gfs2_dirent *dent;
	struct qstr name = { .name = "", .len = 0, .hash = 0 };
	if (!bh)
		return NULL;

	gfs2_trans_add_bh(ip->i_gl, bh, 1);
	gfs2_metatype_set(bh, GFS2_METATYPE_LF, GFS2_FORMAT_LF);
	leaf = (struct gfs2_leaf *)bh->b_data;
	leaf->lf_depth = cpu_to_be16(depth);
	leaf->lf_entries = 0;
	leaf->lf_dirent_format = cpu_to_be32(GFS2_FORMAT_DE);
	leaf->lf_next = 0;
	memset(leaf->lf_reserved, 0, sizeof(leaf->lf_reserved));
	dent = (struct gfs2_dirent *)(leaf+1);
	gfs2_qstr2dirent(&name, bh->b_size - sizeof(struct gfs2_leaf), dent);
	*pbh = bh;
	return leaf;
}

/**
 * dir_make_exhash - Convert a stuffed directory into an ExHash directory
 * @dip: The GFS2 inode
 *
 * Returns: 0 on success, error code otherwise
 */

static int dir_make_exhash(struct inode *inode)
{
	struct gfs2_inode *dip = GFS2_I(inode);
	struct gfs2_sbd *sdp = GFS2_SB(inode);
	struct gfs2_dirent *dent;
	struct qstr args;
	struct buffer_head *bh, *dibh;
	struct gfs2_leaf *leaf;
	int y;
	u32 x;
	__be64 *lp;
	u64 bn;
	int error;

	error = gfs2_meta_inode_buffer(dip, &dibh);
	if (error)
		return error;

	/*  Turn over a new leaf  */

	leaf = new_leaf(inode, &bh, 0);
	if (!leaf)
		return -ENOSPC;
	bn = bh->b_blocknr;

	gfs2_assert(sdp, dip->i_di.di_entries < (1 << 16));
	leaf->lf_entries = cpu_to_be16(dip->i_di.di_entries);

	/*  Copy dirents  */

	gfs2_buffer_copy_tail(bh, sizeof(struct gfs2_leaf), dibh,
			     sizeof(struct gfs2_dinode));

	/*  Find last entry  */

	x = 0;
	args.len = bh->b_size - sizeof(struct gfs2_dinode) +
		   sizeof(struct gfs2_leaf);
	args.name = bh->b_data;
	dent = gfs2_dirent_scan(&dip->i_inode, bh->b_data, bh->b_size,
				gfs2_dirent_last, &args, NULL);
	if (!dent) {
		brelse(bh);
		brelse(dibh);
		return -EIO;
	}
	if (IS_ERR(dent)) {
		brelse(bh);
		brelse(dibh);
		return PTR_ERR(dent);
	}

	/*  Adjust the last dirent's record length
	   (Remember that dent still points to the last entry.)  */

	dent->de_rec_len = cpu_to_be16(be16_to_cpu(dent->de_rec_len) +
		sizeof(struct gfs2_dinode) -
		sizeof(struct gfs2_leaf));

	brelse(bh);

	/*  We're done with the new leaf block, now setup the new
	    hash table.  */

	gfs2_trans_add_bh(dip->i_gl, dibh, 1);
	gfs2_buffer_clear_tail(dibh, sizeof(struct gfs2_dinode));

	lp = (__be64 *)(dibh->b_data + sizeof(struct gfs2_dinode));

	for (x = sdp->sd_hash_ptrs; x--; lp++)
		*lp = cpu_to_be64(bn);

	dip->i_di.di_size = sdp->sd_sb.sb_bsize / 2;
	dip->i_di.di_blocks++;
	gfs2_set_inode_blocks(&dip->i_inode);
	dip->i_di.di_flags |= GFS2_DIF_EXHASH;

	for (x = sdp->sd_hash_ptrs, y = -1; x; x >>= 1, y++) ;
	dip->i_di.di_depth = y;

	gfs2_dinode_out(dip, dibh->b_data);

	brelse(dibh);

	return 0;
}

/**
 * dir_split_leaf - Split a leaf block into two
 * @dip: The GFS2 inode
 * @index:
 * @leaf_no:
 *
 * Returns: 0 on success, error code on failure
 */

static int dir_split_leaf(struct inode *inode, const struct qstr *name)
{
	struct gfs2_inode *dip = GFS2_I(inode);
	struct buffer_head *nbh, *obh, *dibh;
	struct gfs2_leaf *nleaf, *oleaf;
	struct gfs2_dirent *dent = NULL, *prev = NULL, *next = NULL, *new;
	u32 start, len, half_len, divider;
	u64 bn, leaf_no;
	__be64 *lp;
	u32 index;
	int x, moved = 0;
	int error;

	index = name->hash >> (32 - dip->i_di.di_depth);
	error = get_leaf_nr(dip, index, &leaf_no);
	if (error)
		return error;

	/*  Get the old leaf block  */
	error = get_leaf(dip, leaf_no, &obh);
	if (error)
		return error;

	oleaf = (struct gfs2_leaf *)obh->b_data;
	if (dip->i_di.di_depth == be16_to_cpu(oleaf->lf_depth)) {
		brelse(obh);
		return 1; /* can't split */
	}

	gfs2_trans_add_bh(dip->i_gl, obh, 1);

	nleaf = new_leaf(inode, &nbh, be16_to_cpu(oleaf->lf_depth) + 1);
	if (!nleaf) {
		brelse(obh);
		return -ENOSPC;
	}
	bn = nbh->b_blocknr;

	/*  Compute the start and len of leaf pointers in the hash table.  */
	len = 1 << (dip->i_di.di_depth - be16_to_cpu(oleaf->lf_depth));
	half_len = len >> 1;
	if (!half_len) {
		printk(KERN_WARNING "di_depth %u lf_depth %u index %u\n", dip->i_di.di_depth, be16_to_cpu(oleaf->lf_depth), index);
		gfs2_consist_inode(dip);
		error = -EIO;
		goto fail_brelse;
	}

	start = (index & ~(len - 1));

	/* Change the pointers.
	   Don't bother distinguishing stuffed from non-stuffed.
	   This code is complicated enough already. */
	lp = kmalloc(half_len * sizeof(__be64), GFP_NOFS | __GFP_NOFAIL);
	/*  Change the pointers  */
	for (x = 0; x < half_len; x++)
		lp[x] = cpu_to_be64(bn);

	error = gfs2_dir_write_data(dip, (char *)lp, start * sizeof(u64),
				    half_len * sizeof(u64));
	if (error != half_len * sizeof(u64)) {
		if (error >= 0)
			error = -EIO;
		goto fail_lpfree;
	}

	kfree(lp);

	/*  Compute the divider  */
	divider = (start + half_len) << (32 - dip->i_di.di_depth);

	/*  Copy the entries  */
	dirent_first(dip, obh, &dent);

	do {
		next = dent;
		if (dirent_next(dip, obh, &next))
			next = NULL;

		if (!gfs2_dirent_sentinel(dent) &&
		    be32_to_cpu(dent->de_hash) < divider) {
			struct qstr str;
			str.name = (char*)(dent+1);
			str.len = be16_to_cpu(dent->de_name_len);