e2fsck.c

busybox最新版的源码:学习和应用的好东东,多的不说了,大家看后再说吧

 * follows.  We keep a sorted array of first EA blocks and its
 * reference counts.  Once the refcount has dropped to zero, it is
 * removed from the array to save memory space.  Once the EA block is
 * checked, its bit is set in the block_ea_map bitmap.
 */


static errcode_t ea_refcount_create(int size, ext2_refcount_t *ret)
{
	ext2_refcount_t refcount;
	errcode_t       retval;
	size_t          bytes;

	retval = ext2fs_get_mem(sizeof(struct ea_refcount), &refcount);
	if (retval)
		return retval;
	memset(refcount, 0, sizeof(struct ea_refcount));

	if (!size)
		size = 500;
	refcount->size = size;
	bytes = (size_t) (size * sizeof(struct ea_refcount_el));
#ifdef DEBUG
	printf("Refcount allocated %d entries, %d bytes.\n",
	       refcount->size, bytes);
#endif
	retval = ext2fs_get_mem(bytes, &refcount->list);
	if (retval)
		goto errout;
	memset(refcount->list, 0, bytes);

	refcount->count = 0;
	refcount->cursor = 0;

	*ret = refcount;
	return 0;

errout:
	ea_refcount_free(refcount);
	return retval;
}

/*
 * collapse_refcount() --- go through the refcount array, and get rid
 * of any count == zero entries
 */
static void refcount_collapse(ext2_refcount_t refcount)
{
	unsigned int    i, j;
	struct ea_refcount_el   *list;

	list = refcount->list;
	for (i = 0, j = 0; i < refcount->count; i++) {
		if (list[i].ea_count) {
			if (i != j)
				list[j] = list[i];
			j++;
		}
	}
#if defined(DEBUG) || defined(TEST_PROGRAM)
	printf("Refcount_collapse: size was %d, now %d\n",
	       refcount->count, j);
#endif
	refcount->count = j;
}


/*
 * insert_refcount_el() --- Insert a new entry into the sorted list at a
 *      specified position.
 */
static struct ea_refcount_el *insert_refcount_el(ext2_refcount_t refcount,
						 blk_t blk, int pos)
{
	struct ea_refcount_el   *el;
	errcode_t               retval;
	blk_t                   new_size = 0;
	int                     num;

	if (refcount->count >= refcount->size) {
		new_size = refcount->size + 100;
#ifdef DEBUG
		printf("Reallocating refcount %d entries...\n", new_size);
#endif
		retval = ext2fs_resize_mem((size_t) refcount->size *
					   sizeof(struct ea_refcount_el),
					   (size_t) new_size *
					   sizeof(struct ea_refcount_el),
					   &refcount->list);
		if (retval)
			return 0;
		refcount->size = new_size;
	}
	num = (int) refcount->count - pos;
	if (num < 0)
		return 0;       /* should never happen */
	if (num) {
		memmove(&refcount->list[pos+1], &refcount->list[pos],
			sizeof(struct ea_refcount_el) * num);
	}
	refcount->count++;
	el = &refcount->list[pos];
	el->ea_count = 0;
	el->ea_blk = blk;
	return el;
}


/*
 * get_refcount_el() --- given an block number, try to find refcount
 *      information in the sorted list.  If the create flag is set,
 *      and we can't find an entry, create one in the sorted list.
 */
static struct ea_refcount_el *get_refcount_el(ext2_refcount_t refcount,
					      blk_t blk, int create)
{
	float   range;
	int     low, high, mid;
	blk_t   lowval, highval;

	if (!refcount || !refcount->list)
		return 0;
retry:
	low = 0;
	high = (int) refcount->count-1;
	if (create && ((refcount->count == 0) ||
		       (blk > refcount->list[high].ea_blk))) {
		if (refcount->count >= refcount->size)
			refcount_collapse(refcount);

		return insert_refcount_el(refcount, blk,
					  (unsigned) refcount->count);
	}
	if (refcount->count == 0)
		return 0;

	if (refcount->cursor >= refcount->count)
		refcount->cursor = 0;
	if (blk == refcount->list[refcount->cursor].ea_blk)
		return &refcount->list[refcount->cursor++];
#ifdef DEBUG
	printf("Non-cursor get_refcount_el: %u\n", blk);
#endif
	while (low <= high) {
		if (low == high)
			mid = low;
		else {
			/* Interpolate for efficiency */
			lowval = refcount->list[low].ea_blk;
			highval = refcount->list[high].ea_blk;

			if (blk < lowval)
				range = 0;
			else if (blk > highval)
				range = 1;
			else
				range = ((float) (blk - lowval)) /
					(highval - lowval);
			mid = low + ((int) (range * (high-low)));
		}

		if (blk == refcount->list[mid].ea_blk) {
			refcount->cursor = mid+1;
			return &refcount->list[mid];
		}
		if (blk < refcount->list[mid].ea_blk)
			high = mid-1;
		else
			low = mid+1;
	}
	/*
	 * If we need to create a new entry, it should be right at
	 * low (where high will be left at low-1).
	 */
	if (create) {
		if (refcount->count >= refcount->size) {
			refcount_collapse(refcount);
			if (refcount->count < refcount->size)
				goto retry;
		}
		return insert_refcount_el(refcount, blk, low);
	}
	return 0;
}

static errcode_t
ea_refcount_increment(ext2_refcount_t refcount, blk_t blk, int *ret)
{
	struct ea_refcount_el   *el;

	el = get_refcount_el(refcount, blk, 1);
	if (!el)
		return EXT2_ET_NO_MEMORY;
	el->ea_count++;

	if (ret)
		*ret = el->ea_count;
	return 0;
}

static errcode_t
ea_refcount_decrement(ext2_refcount_t refcount, blk_t blk, int *ret)
{
	struct ea_refcount_el   *el;

	el = get_refcount_el(refcount, blk, 0);
	if (!el || el->ea_count == 0)
		return EXT2_ET_INVALID_ARGUMENT;

	el->ea_count--;

	if (ret)
		*ret = el->ea_count;
	return 0;
}

static errcode_t
ea_refcount_store(ext2_refcount_t refcount, blk_t blk, int count)
{
	struct ea_refcount_el   *el;

	/*
	 * Get the refcount element
	 */
	el = get_refcount_el(refcount, blk, count ? 1 : 0);
	if (!el)
		return count ? EXT2_ET_NO_MEMORY : 0;
	el->ea_count = count;
	return 0;
}

static inline void ea_refcount_intr_begin(ext2_refcount_t refcount)
{
	refcount->cursor = 0;
}


static blk_t ea_refcount_intr_next(ext2_refcount_t refcount, int *ret)
{
	struct ea_refcount_el   *list;

	while (1) {
		if (refcount->cursor >= refcount->count)
			return 0;
		list = refcount->list;
		if (list[refcount->cursor].ea_count) {
			if (ret)
				*ret = list[refcount->cursor].ea_count;
			return list[refcount->cursor++].ea_blk;
		}
		refcount->cursor++;
	}
}


/*
 * ehandler.c --- handle bad block errors which come up during the
 *      course of an e2fsck session.
 */


static const char *operation;

static errcode_t
e2fsck_handle_read_error(io_channel channel, unsigned long block, int count,
			 void *data, size_t size FSCK_ATTR((unused)),
			 int actual FSCK_ATTR((unused)), errcode_t error)
{
	int     i;
	char    *p;
	ext2_filsys fs = (ext2_filsys) channel->app_data;
	e2fsck_t ctx;

	ctx = (e2fsck_t) fs->priv_data;

	/*
	 * If more than one block was read, try reading each block
	 * separately.  We could use the actual bytes read to figure
	 * out where to start, but we don't bother.
	 */
	if (count > 1) {
		p = (char *) data;
		for (i=0; i < count; i++, p += channel->block_size, block++) {
			error = io_channel_read_blk(channel, block,
						    1, p);
			if (error)
				return error;
		}
		return 0;
	}
	if (operation)
		printf(_("Error reading block %lu (%s) while %s.  "), block,
		       error_message(error), operation);
	else
		printf(_("Error reading block %lu (%s).  "), block,
		       error_message(error));
	preenhalt(ctx);
	if (ask(ctx, _("Ignore error"), 1)) {
		if (ask(ctx, _("Force rewrite"), 1))
			io_channel_write_blk(channel, block, 1, data);
		return 0;
	}

	return error;
}

static errcode_t
e2fsck_handle_write_error(io_channel channel, unsigned long block, int count,
			const void *data, size_t size FSCK_ATTR((unused)),
			int actual FSCK_ATTR((unused)), errcode_t error)
{
	int             i;
	const char      *p;
	ext2_filsys fs = (ext2_filsys) channel->app_data;
	e2fsck_t ctx;

	ctx = (e2fsck_t) fs->priv_data;

	/*
	 * If more than one block was written, try writing each block
	 * separately.  We could use the actual bytes read to figure
	 * out where to start, but we don't bother.
	 */
	if (count > 1) {
		p = (const char *) data;
		for (i=0; i < count; i++, p += channel->block_size, block++) {
			error = io_channel_write_blk(channel, block,
						     1, p);
			if (error)
				return error;
		}
		return 0;
	}

	if (operation)
		printf(_("Error writing block %lu (%s) while %s.  "), block,
		       error_message(error), operation);
	else
		printf(_("Error writing block %lu (%s).  "), block,
		       error_message(error));
	preenhalt(ctx);
	if (ask(ctx, _("Ignore error"), 1))
		return 0;

	return error;
}

static const char *ehandler_operation(const char *op)
{
	const char *ret = operation;

	operation = op;
	return ret;
}

static void ehandler_init(io_channel channel)
{
	channel->read_error = e2fsck_handle_read_error;
	channel->write_error = e2fsck_handle_write_error;
}

/*
 * journal.c --- code for handling the "ext3" journal
 *
 * Copyright (C) 2000 Andreas Dilger
 * Copyright (C) 2000 Theodore Ts'o
 *
 * Parts of the code are based on fs/jfs/journal.c by Stephen C. Tweedie
 * Copyright (C) 1999 Red Hat Software
 *
 * This file may be redistributed under the terms of the
 * GNU General Public License version 2 or at your discretion
 * any later version.
 */

/*
 * Define USE_INODE_IO to use the inode_io.c / fileio.c codepaths.
 * This creates a larger static binary, and a smaller binary using
 * shared libraries.  It's also probably slightly less CPU-efficient,
 * which is why it's not on by default.  But, it's a good way of
 * testing the functions in inode_io.c and fileio.c.
 */
#undef USE_INODE_IO

/* Kernel compatibility functions for handling the journal.  These allow us
 * to use the recovery.c file virtually unchanged from the kernel, so we
 * don't have to do much to keep kernel and user recovery in sync.
 */
static int journal_bmap(journal_t *journal, blk_t block, unsigned long *phys)
{
#ifdef USE_INODE_IO
	*phys = block;
	return 0;
#else
	struct inode    *inode = journal->j_inode;
	errcode_t       retval;
	blk_t           pblk;

	if (!inode) {
		*phys = block;
		return 0;
	}

	retval= ext2fs_bmap(inode->i_ctx->fs, inode->i_ino,
			    &inode->i_ext2, NULL, 0, block, &pblk);
	*phys = pblk;
	return retval;
#endif
}

static struct buffer_head *getblk(kdev_t kdev, blk_t blocknr, int blocksize)
{
	struct buffer_head *bh;

	bh = e2fsck_allocate_memory(kdev->k_ctx, sizeof(*bh), "block buffer");
	if (!bh)
		return NULL;

	bh->b_ctx = kdev->k_ctx;
	if (kdev->k_dev == K_DEV_FS)
		bh->b_io = kdev->k_ctx->fs->io;
	else
		bh->b_io = kdev->k_ctx->journal_io;
	bh->b_size = blocksize;
	bh->b_blocknr = blocknr;

	return bh;
}

static void sync_blockdev(kdev_t kdev)
{
	io_channel      io;

	if (kdev->k_dev == K_DEV_FS)
		io = kdev->k_ctx->fs->io;
	else
		io = kdev->k_ctx->journal_io;

	io_channel_flush(io);
}

static void ll_rw_block(int rw, int nr, struct buffer_head *bhp[])
{
	int retval;
	struct buffer_head *bh;

	for (; nr > 0; --nr) {
		bh = *bhp++;
		if (rw == READ && !bh->b_uptodate) {
			retval = io_channel_read_blk(bh->b_io,
						     bh->b_blocknr,
						     1, bh->b_data);
			if (retval) {
				bb_error_msg("while reading block %lu",
					(unsigned long) bh->b_blocknr);
				bh->b_err = retval;
				continue;
			}
			bh->b_uptodate = 1;
		} else if (rw == WRITE && bh->b_dirty) {
			retval = io_channel_write_blk(bh->b_io,
						      bh->b_blocknr,
						      1, bh->b_data);
			if (retval) {
				bb_error_msg("while writing block %lu",
					(unsigned long) bh->b_blocknr);
				bh->b_err = retval;
				continue;
			}
			bh->b_dirty = 0;
			bh->b_uptodate = 1;
		}
	}
}

static void mark_buffer_dirty(struct buffer_head *bh)
{
	bh->b_dirty = 1;
}

static inline void mark_buffer_clean(struct buffer_head * bh)
{
	bh->b_dirty = 0;
}

static void brelse(struct buffer_head *bh)
{
	if (bh->b_dirty)
		ll_rw_block(WRITE, 1, &bh);
	ext2fs_free_mem(&bh);
}

static int buffer_uptodate(struct buffer_head *bh)
{
	return bh->b_uptodate;
}

static inline void mark_buffer_uptodate(struct buffer_head *bh, int val)
{
	bh->b_uptodate = val;
}

static void wait_on_buffer(struct buffer_head *bh)
{
	if (!bh->b_uptodate)
		ll_rw_block(READ, 1, &bh);
}