Release 4.10 fs/gfs2/dir.c

/*
 * Copyright (C) Sistina Software, Inc.  1997-2003 All rights reserved.
 * Copyright (C) 2004-2006 Red Hat, Inc.  All rights reserved.
 *
 * This copyrighted material is made available to anyone wishing to use,
 * modify, copy, or redistribute it subject to the terms and conditions
 * of the GNU General Public License version 2.
 */

/*
 * Implements Extendible Hashing as described in:
 *   "Extendible Hashing" by Fagin, et al in
 *     __ACM Trans. on Database Systems__, Sept 1979.
 *
 *
 * Here's the layout of dirents which is essentially the same as that of ext2
 * within a single block. The field de_name_len is the number of bytes
 * actually required for the name (no null terminator). The field de_rec_len
 * is the number of bytes allocated to the dirent. The offset of the next
 * dirent in the block is (dirent + dirent->de_rec_len). When a dirent is
 * deleted, the preceding dirent inherits its allocated space, ie
 * prev->de_rec_len += deleted->de_rec_len. Since the next dirent is obtained
 * by adding de_rec_len to the current dirent, this essentially causes the
 * deleted dirent to get jumped over when iterating through all the dirents.
 *
 * When deleting the first dirent in a block, there is no previous dirent so
 * the field de_ino is set to zero to designate it as deleted. When allocating
 * a dirent, gfs2_dirent_alloc iterates through the dirents in a block. If the
 * first dirent has (de_ino == 0) and de_rec_len is large enough, this first
 * dirent is allocated. Otherwise it must go through all the 'used' dirents
 * searching for one in which the amount of total space minus the amount of
 * used space will provide enough space for the new dirent.
 *
 * There are two types of blocks in which dirents reside. In a stuffed dinode,
 * the dirents begin at offset sizeof(struct gfs2_dinode) from the beginning of
 * the block.  In leaves, they begin at offset sizeof(struct gfs2_leaf) from the
 * beginning of the leaf block. The dirents reside in leaves when
 *
 * dip->i_diskflags & GFS2_DIF_EXHASH is true
 *
 * Otherwise, the dirents are "linear", within a single stuffed dinode block.
 *
 * When the dirents are in leaves, the actual contents of the directory file are
 * used as an array of 64-bit block pointers pointing to the leaf blocks. The
 * dirents are NOT in the directory file itself. There can be more than one
 * block pointer in the array that points to the same leaf. In fact, when a
 * directory is first converted from linear to exhash, all of the pointers
 * point to the same leaf.
 *
 * When a leaf is completely full, the size of the hash table can be
 * doubled unless it is already at the maximum size which is hard coded into
 * GFS2_DIR_MAX_DEPTH. After that, leaves are chained together in a linked list,
 * but never before the maximum hash table size has been reached.
 */


#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt

#include <linux/slab.h>
#include <linux/spinlock.h>
#include <linux/buffer_head.h>
#include <linux/sort.h>
#include <linux/gfs2_ondisk.h>
#include <linux/crc32.h>
#include <linux/vmalloc.h>
#include <linux/bio.h>

#include "gfs2.h"
#include "incore.h"
#include "dir.h"
#include "glock.h"
#include "inode.h"
#include "meta_io.h"
#include "quota.h"
#include "rgrp.h"
#include "trans.h"
#include "bmap.h"
#include "util.h"


#define IS_LEAF     1 
/* Hashed (leaf) directory */

#define IS_DINODE   2 
/* Linear (stuffed dinode block) directory */


#define MAX_RA_BLOCKS 32 
/* max read-ahead blocks */


#define gfs2_disk_hash2offset(h) (((u64)(h)) >> 1)

#define gfs2_dir_offset2hash(p) ((u32)(((u64)(p)) << 1))

#define GFS2_HASH_INDEX_MASK 0xffffc000

#define GFS2_USE_HASH_FLAG 0x2000


struct qstr gfs2_qdot __read_mostly;

struct qstr gfs2_qdotdot __read_mostly;


typedef int (*gfs2_dscan_t)(const struct gfs2_dirent *dent,
			    const struct qstr *name, void *opaque);



int gfs2_dir_get_new_buffer(struct gfs2_inode *ip, u64 block,
			    struct buffer_head **bhp)
{
	struct buffer_head *bh;

	bh = gfs2_meta_new(ip->i_gl, block);
	gfs2_trans_add_meta(ip->i_gl, bh);
	gfs2_metatype_set(bh, GFS2_METATYPE_JD, GFS2_FORMAT_JD);
	gfs2_buffer_clear_tail(bh, sizeof(struct gfs2_meta_header));
	*bhp = bh;
	return 0;
}

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static int gfs2_dir_get_existing_buffer(struct gfs2_inode *ip, u64 block,
					struct buffer_head **bhp)
{
	struct buffer_head *bh;
	int error;

	error = gfs2_meta_read(ip->i_gl, block, DIO_WAIT, 0, &bh);
	if (error)
		return error;
	if (gfs2_metatype_check(GFS2_SB(&ip->i_inode), bh, GFS2_METATYPE_JD)) {
		brelse(bh);
		return -EIO;
	}
	*bhp = bh;
	return 0;
}

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static int gfs2_dir_write_stuffed(struct gfs2_inode *ip, const char *buf,
				  unsigned int offset, unsigned int size)
{
	struct buffer_head *dibh;
	int error;

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

	gfs2_trans_add_meta(ip->i_gl, dibh);
	memcpy(dibh->b_data + offset + sizeof(struct gfs2_dinode), buf, size);
	if (ip->i_inode.i_size < offset + size)
		i_size_write(&ip->i_inode, offset + size);
	ip->i_inode.i_mtime = ip->i_inode.i_ctime = current_time(&ip->i_inode);
	gfs2_dinode_out(ip, dibh->b_data);

	brelse(dibh);

	return size;
}



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/**
 * gfs2_dir_write_data - Write directory information to the inode
 * @ip: The GFS2 inode
 * @buf: The buffer containing information to be written
 * @offset: The file offset to start writing at
 * @size: The amount of data to write
 *
 * Returns: The number of bytes correctly written or error code
 */


static int gfs2_dir_write_data(struct gfs2_inode *ip, const char *buf,
			       u64 offset, unsigned int size)
{
	struct gfs2_sbd *sdp = GFS2_SB(&ip->i_inode);
	struct buffer_head *dibh;
	u64 lblock, dblock;
	u32 extlen = 0;
	unsigned int o;
	int copied = 0;
	int error = 0;
	int new = 0;

	if (!size)
		return 0;

	if (gfs2_is_stuffed(ip) &&
	    offset + size <= sdp->sd_sb.sb_bsize - sizeof(struct gfs2_dinode))
		return gfs2_dir_write_stuffed(ip, buf, (unsigned int)offset,
					      size);

	if (gfs2_assert_warn(sdp, gfs2_is_jdata(ip)))
		return -EINVAL;

	if (gfs2_is_stuffed(ip)) {
		error = gfs2_unstuff_dinode(ip, NULL);
		if (error)
			return error;
	}

	lblock = offset;
	o = do_div(lblock, sdp->sd_jbsize) + sizeof(struct gfs2_meta_header);

	while (copied < size) {
		unsigned int amount;
		struct buffer_head *bh;

		amount = size - copied;
		if (amount > sdp->sd_sb.sb_bsize - o)
			amount = sdp->sd_sb.sb_bsize - o;

		if (!extlen) {
			new = 1;
			error = gfs2_extent_map(&ip->i_inode, lblock, &new,
						&dblock, &extlen);
			if (error)
				goto fail;
			error = -EIO;
			if (gfs2_assert_withdraw(sdp, dblock))
				goto fail;
		}

		if (amount == sdp->sd_jbsize || new)
			error = gfs2_dir_get_new_buffer(ip, dblock, &bh);
		else
			error = gfs2_dir_get_existing_buffer(ip, dblock, &bh);

		if (error)
			goto fail;

		gfs2_trans_add_meta(ip->i_gl, bh);
		memcpy(bh->b_data + o, buf, amount);
		brelse(bh);

		buf += amount;
		copied += amount;
		lblock++;
		dblock++;
		extlen--;

		o = sizeof(struct gfs2_meta_header);
	}

out:
	error = gfs2_meta_inode_buffer(ip, &dibh);
	if (error)
		return error;

	if (ip->i_inode.i_size < offset + copied)
		i_size_write(&ip->i_inode, offset + copied);
	ip->i_inode.i_mtime = ip->i_inode.i_ctime = current_time(&ip->i_inode);

	gfs2_trans_add_meta(ip->i_gl, dibh);
	gfs2_dinode_out(ip, dibh->b_data);
	brelse(dibh);

	return copied;
fail:
	if (copied)
		goto out;
	return error;
}

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static int gfs2_dir_read_stuffed(struct gfs2_inode *ip, __be64 *buf,
				 unsigned int size)
{
	struct buffer_head *dibh;
	int error;

	error = gfs2_meta_inode_buffer(ip, &dibh);
	if (!error) {
		memcpy(buf, dibh->b_data + sizeof(struct gfs2_dinode), size);
		brelse(dibh);
	}

	return (error) ? error : size;
}


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/**
 * gfs2_dir_read_data - Read a data from a directory inode
 * @ip: The GFS2 Inode
 * @buf: The buffer to place result into
 * @size: Amount of data to transfer
 *
 * Returns: The amount of data actually copied or the error
 */


static int gfs2_dir_read_data(struct gfs2_inode *ip, __be64 *buf,
			      unsigned int size)
{
	struct gfs2_sbd *sdp = GFS2_SB(&ip->i_inode);
	u64 lblock, dblock;
	u32 extlen = 0;
	unsigned int o;
	int copied = 0;
	int error = 0;

	if (gfs2_is_stuffed(ip))
		return gfs2_dir_read_stuffed(ip, buf, size);

	if (gfs2_assert_warn(sdp, gfs2_is_jdata(ip)))
		return -EINVAL;

	lblock = 0;
	o = do_div(lblock, sdp->sd_jbsize) + sizeof(struct gfs2_meta_header);

	while (copied < size) {
		unsigned int amount;
		struct buffer_head *bh;
		int new;

		amount = size - copied;
		if (amount > sdp->sd_sb.sb_bsize - o)
			amount = sdp->sd_sb.sb_bsize - o;

		if (!extlen) {
			new = 0;
			error = gfs2_extent_map(&ip->i_inode, lblock, &new,
						&dblock, &extlen);
			if (error || !dblock)
				goto fail;
			BUG_ON(extlen < 1);
			bh = gfs2_meta_ra(ip->i_gl, dblock, extlen);
		} else {
			error = gfs2_meta_read(ip->i_gl, dblock, DIO_WAIT, 0, &bh);
			if (error)
				goto fail;
		}
		error = gfs2_metatype_check(sdp, bh, GFS2_METATYPE_JD);
		if (error) {
			brelse(bh);
			goto fail;
		}
		dblock++;
		extlen--;
		memcpy(buf, bh->b_data + o, amount);
		brelse(bh);
		buf += (amount/sizeof(__be64));
		copied += amount;
		lblock++;
		o = sizeof(struct gfs2_meta_header);
	}

	return copied;
fail:
	return (copied) ? copied : error;
}

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/**
 * gfs2_dir_get_hash_table - Get pointer to the dir hash table
 * @ip: The inode in question
 *
 * Returns: The hash table or an error
 */



static __be64 *gfs2_dir_get_hash_table(struct gfs2_inode *ip)
{
	struct inode *inode = &ip->i_inode;
	int ret;
	u32 hsize;
	__be64 *hc;

	BUG_ON(!(ip->i_diskflags & GFS2_DIF_EXHASH));

	hc = ip->i_hash_cache;
	if (hc)
		return hc;

	hsize = BIT(ip->i_depth);
	hsize *= sizeof(__be64);
	if (hsize != i_size_read(&ip->i_inode)) {
		gfs2_consist_inode(ip);
		return ERR_PTR(-EIO);
	}

	hc = kmalloc(hsize, GFP_NOFS | __GFP_NOWARN);
	if (hc == NULL)
		hc = __vmalloc(hsize, GFP_NOFS, PAGE_KERNEL);

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

	ret = gfs2_dir_read_data(ip, hc, hsize);
	if (ret < 0) {
		kvfree(hc);
		return ERR_PTR(ret);
	}

	spin_lock(&inode->i_lock);
	if (likely(!ip->i_hash_cache)) {
		ip->i_hash_cache = hc;
		hc = NULL;
	}
	spin_unlock(&inode->i_lock);
	kvfree(hc);

	return ip->i_hash_cache;
}

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/**
 * gfs2_dir_hash_inval - Invalidate dir hash
 * @ip: The directory inode
 *
 * Must be called with an exclusive glock, or during glock invalidation.
 */


void gfs2_dir_hash_inval(struct gfs2_inode *ip)
{
	__be64 *hc;

	spin_lock(&ip->i_inode.i_lock);
	hc = ip->i_hash_cache;
	ip->i_hash_cache = NULL;
	spin_unlock(&ip->i_inode.i_lock);

	kvfree(hc);
}

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static inline int gfs2_dirent_sentinel(const struct gfs2_dirent *dent)
{
	return dent->de_inum.no_addr == 0 || dent->de_inum.no_formal_ino == 0;
}

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static inline int __gfs2_dirent_find(const struct gfs2_dirent *dent,
				     const struct qstr *name, int ret)
{
	if (!gfs2_dirent_sentinel(dent) &&
	    be32_to_cpu(dent->de_hash) == name->hash &&
	    be16_to_cpu(dent->de_name_len) == name->len &&
	    memcmp(dent+1, name->name, name->len) == 0)
		return ret;
	return 0;
}

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static int gfs2_dirent_find(const struct gfs2_dirent *dent,
			    const struct qstr *name,
			    void *opaque)
{
	return __gfs2_dirent_find(dent, name, 1);
}

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static int gfs2_dirent_prev(const struct gfs2_dirent *dent,
			    const struct qstr *name,
			    void *opaque)
{
	return __gfs2_dirent_find(dent, name, 2);
}

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/*
 * name->name holds ptr to start of block.
 * name->len holds size of block.
 */


static int gfs2_dirent_last(const struct gfs2_dirent *dent,
			    const struct qstr *name,
			    void *opaque)
{
	const char *start = name->name;
	const char *end = (const char *)dent + be16_to_cpu(dent->de_rec_len);
	if (name->len == (end - start))
		return 1;
	return 0;
}

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/* Look for the dirent that contains the offset specified in data. Once we
 * find that dirent, there must be space available there for the new dirent */


static int gfs2_dirent_find_offset(const struct gfs2_dirent *dent,
				  const struct qstr *name,
				  void *ptr)
{
	unsigned required = GFS2_DIRENT_SIZE(name->len);
	unsigned actual = GFS2_DIRENT_SIZE(be16_to_cpu(dent->de_name_len));
	unsigned totlen = be16_to_cpu(dent->de_rec_len);

	if (ptr < (void *)dent || ptr >= (void *)dent + totlen)
		return 0;
	if (gfs2_dirent_sentinel(dent))
		actual = 0;
	if (ptr < (void *)dent + actual)
		return -1;
	if ((void *)dent + totlen >= ptr + required)
		return 1;
	return -1;
}

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static int gfs2_dirent_find_space(const struct gfs2_dirent *dent,
				  const struct qstr *name,
				  void *opaque)
{
	unsigned required = GFS2_DIRENT_SIZE(name->len);
	unsigned actual = GFS2_DIRENT_SIZE(be16_to_cpu(dent->de_name_len));
	unsigned totlen = be16_to_cpu(dent->de_rec_len);

	if (gfs2_dirent_sentinel(dent))
		actual = 0;
	if (totlen - actual >= required)
		return 1;
	return 0;
}

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struct dirent_gather {
	
const struct gfs2_dirent **pdent;
	
unsigned offset;
};



static int gfs2_dirent_gather(const struct gfs2_dirent *dent,
			      const struct qstr *name,
			      void *opaque)
{
	struct dirent_gather *g = opaque;
	if (!gfs2_dirent_sentinel(dent)) {
		g->pdent[g->offset++] = dent;
	}
	return 0;
}

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/*
 * Other possible things to check:
 * - Inode located within filesystem size (and on valid block)
 * - Valid directory entry type
 * Not sure how heavy-weight we want to make this... could also check
 * hash is correct for example, but that would take a lot of extra time.
 * For now the most important thing is to check that the various sizes
 * are correct.
 */


static int gfs2_check_dirent(struct gfs2_dirent *dent, unsigned int offset,
			     unsigned int size, unsigned int len, int first)
{
	const char *msg = "gfs2_dirent too small";
	if (unlikely(size < sizeof(struct gfs2_dirent)))
		goto error;
	msg = "gfs2_dirent misaligned";
	if (unlikely(offset & 0x7))
		goto error;
	msg = "gfs2_dirent points beyond end of block";
	if (unlikely(offset + size > len))
		goto error;
	msg = "zero inode number";
	if (unlikely(!first && gfs2_dirent_sentinel(dent)))
		goto error;
	msg = "name length is greater than space in dirent";
	if (!gfs2_dirent_sentinel(dent) &&
	    unlikely(sizeof(struct gfs2_dirent)+be16_to_cpu(dent->de_name_len) >
		     size))
		goto error;
	return 0;
error:
	pr_warn("%s: %s (%s)\n",
		__func__, msg, first ? "first in block" : "not first in block");
	return -EIO;
}

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static int gfs2_dirent_offset(const void *buf)
{
	const struct gfs2_meta_header *h = buf;
	int offset;

	BUG_ON(buf == NULL);

	switch(be32_to_cpu(h->mh_type)) {
	case GFS2_METATYPE_LF:
		offset = sizeof(struct gfs2_leaf);
		break;
	case GFS2_METATYPE_DI:
		offset = sizeof(struct gfs2_dinode);
		break;
	default:
		goto wrong_type;
	}
	return offset;
wrong_type:
	pr_warn("%s: wrong block type %u\n", __func__, be32_to_cpu(h->mh_type));
	return -1;
}

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1
16.67%
fabian frederick
fabian frederick
1
1.10%
1
16.67%
Total
91
100.00%
6
100.00%



static struct gfs2_dirent *gfs2_dirent_scan(struct inode *inode, void *buf,
					    unsigned int len, gfs2_dscan_t scan,
					    const struct qstr *name,
					    void *opaque)
{
	struct gfs2_dirent *dent, *prev;
	unsigned offset;
	unsigned size;
	int ret = 0;

	ret = gfs2_dirent_offset(buf);
	if (ret < 0)
		goto consist_inode;

	offset = ret;
	prev = NULL;
	dent = buf + offset;
	size = be16_to_cpu(dent->de_rec_len);
	if (gfs2_check_dirent(dent, offset, size, len, 1))
		goto consist_inode;
	do {
		ret = scan(dent, name, opaque);
		if (ret)
			break;
		offset += size;
		if (offset == len)
			break;
		prev = dent;
		dent = buf + offset;
		size = be16_to_cpu(dent->de_rec_len);
		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);
}

Contributors
Person
Tokens
Prop
Commits
CommitProp
steven whitehouse
steven whitehouse
196
81.33%
6
85.71%
david teigland
david teigland
45
18.67%
1
14.29%
Total
241
100.00%
7
100.00%



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;
}

Contributors
Person
Tokens
Prop
Commits
CommitProp
steven whitehouse
steven whitehouse
89
100.00%
1
100.00%
Total
89
100.00%
1
100.00%

/**
 * 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;
}

Contributors
Person
Tokens
Prop
Commits
CommitProp
steven whitehouse
steven whitehouse
68
53.97%
4
80.00%
david teigland
david teigland
58
46.03%
1
20.00%
Total
126
100.00%
5
100.00%

/**
 * 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_meta(dip->i_gl, bh);

	/* 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 +