bmap.c

linux 内核源代码

	if (height < ip->i_di.di_height - 1)
		for (; top < bottom; top++, first = 0) {
			if (!*top)
				continue;

			bn = be64_to_cpu(*top);

			error = recursive_scan(ip, dibh, mp, height + 1, bn,
					       first, bc, data);
			if (error)
				break;
		}

out:
	brelse(bh);
	return error;
}

/**
 * do_strip - Look for a layer a particular layer of the file and strip it off
 * @ip: the inode
 * @dibh: the dinode buffer
 * @bh: A buffer of pointers
 * @top: The first pointer in the buffer
 * @bottom: One more than the last pointer
 * @height: the height this buffer is at
 * @data: a pointer to a struct strip_mine
 *
 * Returns: errno
 */

static int do_strip(struct gfs2_inode *ip, struct buffer_head *dibh,
		    struct buffer_head *bh, __be64 *top, __be64 *bottom,
		    unsigned int height, void *data)
{
	struct strip_mine *sm = data;
	struct gfs2_sbd *sdp = GFS2_SB(&ip->i_inode);
	struct gfs2_rgrp_list rlist;
	u64 bn, bstart;
	u32 blen;
	__be64 *p;
	unsigned int rg_blocks = 0;
	int metadata;
	unsigned int revokes = 0;
	int x;
	int error;

	if (!*top)
		sm->sm_first = 0;

	if (height != sm->sm_height)
		return 0;

	if (sm->sm_first) {
		top++;
		sm->sm_first = 0;
	}

	metadata = (height != ip->i_di.di_height - 1);
	if (metadata)
		revokes = (height) ? sdp->sd_inptrs : sdp->sd_diptrs;

	error = gfs2_rindex_hold(sdp, &ip->i_alloc.al_ri_gh);
	if (error)
		return error;

	memset(&rlist, 0, sizeof(struct gfs2_rgrp_list));
	bstart = 0;
	blen = 0;

	for (p = top; p < bottom; p++) {
		if (!*p)
			continue;

		bn = be64_to_cpu(*p);

		if (bstart + blen == bn)
			blen++;
		else {
			if (bstart)
				gfs2_rlist_add(sdp, &rlist, bstart);

			bstart = bn;
			blen = 1;
		}
	}

	if (bstart)
		gfs2_rlist_add(sdp, &rlist, bstart);
	else
		goto out; /* Nothing to do */

	gfs2_rlist_alloc(&rlist, LM_ST_EXCLUSIVE, 0);

	for (x = 0; x < rlist.rl_rgrps; x++) {
		struct gfs2_rgrpd *rgd;
		rgd = rlist.rl_ghs[x].gh_gl->gl_object;
		rg_blocks += rgd->rd_length;
	}

	error = gfs2_glock_nq_m(rlist.rl_rgrps, rlist.rl_ghs);
	if (error)
		goto out_rlist;

	error = gfs2_trans_begin(sdp, rg_blocks + RES_DINODE +
				 RES_INDIRECT + RES_STATFS + RES_QUOTA,
				 revokes);
	if (error)
		goto out_rg_gunlock;

	down_write(&ip->i_rw_mutex);

	gfs2_trans_add_bh(ip->i_gl, dibh, 1);
	gfs2_trans_add_bh(ip->i_gl, bh, 1);

	bstart = 0;
	blen = 0;

	for (p = top; p < bottom; p++) {
		if (!*p)
			continue;

		bn = be64_to_cpu(*p);

		if (bstart + blen == bn)
			blen++;
		else {
			if (bstart) {
				if (metadata)
					gfs2_free_meta(ip, bstart, blen);
				else
					gfs2_free_data(ip, bstart, blen);
			}

			bstart = bn;
			blen = 1;
		}

		*p = 0;
		if (!ip->i_di.di_blocks)
			gfs2_consist_inode(ip);
		ip->i_di.di_blocks--;
		gfs2_set_inode_blocks(&ip->i_inode);
	}
	if (bstart) {
		if (metadata)
			gfs2_free_meta(ip, bstart, blen);
		else
			gfs2_free_data(ip, bstart, blen);
	}

	ip->i_inode.i_mtime = ip->i_inode.i_ctime = CURRENT_TIME;

	gfs2_dinode_out(ip, dibh->b_data);

	up_write(&ip->i_rw_mutex);

	gfs2_trans_end(sdp);

out_rg_gunlock:
	gfs2_glock_dq_m(rlist.rl_rgrps, rlist.rl_ghs);
out_rlist:
	gfs2_rlist_free(&rlist);
out:
	gfs2_glock_dq_uninit(&ip->i_alloc.al_ri_gh);
	return error;
}

/**
 * do_grow - Make a file look bigger than it is
 * @ip: the inode
 * @size: the size to set the file to
 *
 * Called with an exclusive lock on @ip.
 *
 * Returns: errno
 */

static int do_grow(struct gfs2_inode *ip, u64 size)
{
	struct gfs2_sbd *sdp = GFS2_SB(&ip->i_inode);
	struct gfs2_alloc *al;
	struct buffer_head *dibh;
	unsigned int h;
	int error;

	al = gfs2_alloc_get(ip);

	error = gfs2_quota_lock(ip, NO_QUOTA_CHANGE, NO_QUOTA_CHANGE);
	if (error)
		goto out;

	error = gfs2_quota_check(ip, ip->i_inode.i_uid, ip->i_inode.i_gid);
	if (error)
		goto out_gunlock_q;

	al->al_requested = sdp->sd_max_height + RES_DATA;

	error = gfs2_inplace_reserve(ip);
	if (error)
		goto out_gunlock_q;

	error = gfs2_trans_begin(sdp,
			sdp->sd_max_height + al->al_rgd->rd_length +
			RES_JDATA + RES_DINODE + RES_STATFS + RES_QUOTA, 0);
	if (error)
		goto out_ipres;

	if (size > sdp->sd_sb.sb_bsize - sizeof(struct gfs2_dinode)) {
		if (gfs2_is_stuffed(ip)) {
			error = gfs2_unstuff_dinode(ip, NULL);
			if (error)
				goto out_end_trans;
		}

		h = calc_tree_height(ip, size);
		if (ip->i_di.di_height < h) {
			down_write(&ip->i_rw_mutex);
			error = build_height(&ip->i_inode, h);
			up_write(&ip->i_rw_mutex);
			if (error)
				goto out_end_trans;
		}
	}

	ip->i_di.di_size = size;
	ip->i_inode.i_mtime = ip->i_inode.i_ctime = CURRENT_TIME;

	error = gfs2_meta_inode_buffer(ip, &dibh);
	if (error)
		goto out_end_trans;

	gfs2_trans_add_bh(ip->i_gl, dibh, 1);
	gfs2_dinode_out(ip, dibh->b_data);
	brelse(dibh);

out_end_trans:
	gfs2_trans_end(sdp);
out_ipres:
	gfs2_inplace_release(ip);
out_gunlock_q:
	gfs2_quota_unlock(ip);
out:
	gfs2_alloc_put(ip);
	return error;
}


/**
 * gfs2_block_truncate_page - Deal with zeroing out data for truncate
 *
 * This is partly borrowed from ext3.
 */
static int gfs2_block_truncate_page(struct address_space *mapping)
{
	struct inode *inode = mapping->host;
	struct gfs2_inode *ip = GFS2_I(inode);
	struct gfs2_sbd *sdp = GFS2_SB(inode);
	loff_t from = inode->i_size;
	unsigned long index = from >> PAGE_CACHE_SHIFT;
	unsigned offset = from & (PAGE_CACHE_SIZE-1);
	unsigned blocksize, iblock, length, pos;
	struct buffer_head *bh;
	struct page *page;
	int err;

	page = grab_cache_page(mapping, index);
	if (!page)
		return 0;

	blocksize = inode->i_sb->s_blocksize;
	length = blocksize - (offset & (blocksize - 1));
	iblock = index << (PAGE_CACHE_SHIFT - inode->i_sb->s_blocksize_bits);

	if (!page_has_buffers(page))
		create_empty_buffers(page, blocksize, 0);

	/* Find the buffer that contains "offset" */
	bh = page_buffers(page);
	pos = blocksize;
	while (offset >= pos) {
		bh = bh->b_this_page;
		iblock++;
		pos += blocksize;
	}

	err = 0;

	if (!buffer_mapped(bh)) {
		gfs2_get_block(inode, iblock, bh, 0);
		/* unmapped? It's a hole - nothing to do */
		if (!buffer_mapped(bh))
			goto unlock;
	}

	/* Ok, it's mapped. Make sure it's up-to-date */
	if (PageUptodate(page))
		set_buffer_uptodate(bh);

	if (!buffer_uptodate(bh)) {
		err = -EIO;
		ll_rw_block(READ, 1, &bh);
		wait_on_buffer(bh);
		/* Uhhuh. Read error. Complain and punt. */
		if (!buffer_uptodate(bh))
			goto unlock;
		err = 0;
	}

	if (sdp->sd_args.ar_data == GFS2_DATA_ORDERED || gfs2_is_jdata(ip))
		gfs2_trans_add_bh(ip->i_gl, bh, 0);

	zero_user_page(page, offset, length, KM_USER0);

unlock:
	unlock_page(page);
	page_cache_release(page);
	return err;
}

static int trunc_start(struct gfs2_inode *ip, u64 size)
{
	struct gfs2_sbd *sdp = GFS2_SB(&ip->i_inode);
	struct buffer_head *dibh;
	int journaled = gfs2_is_jdata(ip);
	int error;

	error = gfs2_trans_begin(sdp,
				 RES_DINODE + (journaled ? RES_JDATA : 0), 0);
	if (error)
		return error;

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

	if (gfs2_is_stuffed(ip)) {
		ip->i_di.di_size = size;
		ip->i_inode.i_mtime = ip->i_inode.i_ctime = CURRENT_TIME;
		gfs2_trans_add_bh(ip->i_gl, dibh, 1);
		gfs2_dinode_out(ip, dibh->b_data);
		gfs2_buffer_clear_tail(dibh, sizeof(struct gfs2_dinode) + size);
		error = 1;

	} else {
		if (size & (u64)(sdp->sd_sb.sb_bsize - 1))
			error = gfs2_block_truncate_page(ip->i_inode.i_mapping);

		if (!error) {
			ip->i_di.di_size = size;
			ip->i_inode.i_mtime = ip->i_inode.i_ctime = CURRENT_TIME;
			ip->i_di.di_flags |= GFS2_DIF_TRUNC_IN_PROG;
			gfs2_trans_add_bh(ip->i_gl, dibh, 1);
			gfs2_dinode_out(ip, dibh->b_data);
		}
	}

	brelse(dibh);

out:
	gfs2_trans_end(sdp);
	return error;
}

static int trunc_dealloc(struct gfs2_inode *ip, u64 size)
{
	unsigned int height = ip->i_di.di_height;
	u64 lblock;
	struct metapath mp;
	int error;

	if (!size)
		lblock = 0;
	else
		lblock = (size - 1) >> GFS2_SB(&ip->i_inode)->sd_sb.sb_bsize_shift;

	find_metapath(ip, lblock, &mp);
	gfs2_alloc_get(ip);

	error = gfs2_quota_hold(ip, NO_QUOTA_CHANGE, NO_QUOTA_CHANGE);
	if (error)
		goto out;

	while (height--) {
		struct strip_mine sm;
		sm.sm_first = !!size;
		sm.sm_height = height;

		error = recursive_scan(ip, NULL, &mp, 0, 0, 1, do_strip, &sm);
		if (error)
			break;
	}

	gfs2_quota_unhold(ip);

out:
	gfs2_alloc_put(ip);
	return error;
}

static int trunc_end(struct gfs2_inode *ip)
{
	struct gfs2_sbd *sdp = GFS2_SB(&ip->i_inode);
	struct buffer_head *dibh;
	int error;

	error = gfs2_trans_begin(sdp, RES_DINODE, 0);
	if (error)
		return error;

	down_write(&ip->i_rw_mutex);

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

	if (!ip->i_di.di_size) {
		ip->i_di.di_height = 0;
		ip->i_di.di_goal_meta =
			ip->i_di.di_goal_data =
			ip->i_no_addr;
		gfs2_buffer_clear_tail(dibh, sizeof(struct gfs2_dinode));
	}
	ip->i_inode.i_mtime = ip->i_inode.i_ctime = CURRENT_TIME;
	ip->i_di.di_flags &= ~GFS2_DIF_TRUNC_IN_PROG;

	gfs2_trans_add_bh(ip->i_gl, dibh, 1);
	gfs2_dinode_out(ip, dibh->b_data);
	brelse(dibh);

out:
	up_write(&ip->i_rw_mutex);
	gfs2_trans_end(sdp);
	return error;
}

/**
 * do_shrink - make a file smaller
 * @ip: the inode
 * @size: the size to make the file
 * @truncator: function to truncate the last partial block
 *
 * Called with an exclusive lock on @ip.
 *
 * Returns: errno
 */

static int do_shrink(struct gfs2_inode *ip, u64 size)
{
	int error;

	error = trunc_start(ip, size);
	if (error < 0)
		return error;
	if (error > 0)
		return 0;

	error = trunc_dealloc(ip, size);
	if (!error)
		error = trunc_end(ip);

	return error;
}

static int do_touch(struct gfs2_inode *ip, u64 size)
{
	struct gfs2_sbd *sdp = GFS2_SB(&ip->i_inode);
	struct buffer_head *dibh;
	int error;

	error = gfs2_trans_begin(sdp, RES_DINODE, 0);
	if (error)
		return error;

	down_write(&ip->i_rw_mutex);

	error = gfs2_meta_inode_buffer(ip, &dibh);
	if (error)
		goto do_touch_out;

	ip->i_inode.i_mtime = ip->i_inode.i_ctime = CURRENT_TIME;
	gfs2_trans_add_bh(ip->i_gl, dibh, 1);
	gfs2_dinode_out(ip, dibh->b_data);
	brelse(dibh);

do_touch_out:
	up_write(&ip->i_rw_mutex);
	gfs2_trans_end(sdp);
	return error;
}

/**
 * gfs2_truncatei - make a file a given size
 * @ip: the inode
 * @size: the size to make the file
 * @truncator: function to truncate the last partial block
 *
 * The file size can grow, shrink, or stay the same size.
 *
 * Returns: errno
 */

int gfs2_truncatei(struct gfs2_inode *ip, u64 size)
{
	int error;

	if (gfs2_assert_warn(GFS2_SB(&ip->i_inode), S_ISREG(ip->i_inode.i_mode)))
		return -EINVAL;

	if (size > ip->i_di.di_size)
		error = do_grow(ip, size);
	else if (size < ip->i_di.di_size)
		error = do_shrink(ip, size);
	else
		/* update time stamps */
		error = do_touch(ip, size);

	return error;
}

int gfs2_truncatei_resume(struct gfs2_inode *ip)
{
	int error;
	error = trunc_dealloc(ip, ip->i_di.di_size);
	if (!error)
		error = trunc_end(ip);
	return error;
}

int gfs2_file_dealloc(struct gfs2_inode *ip)
{
	return trunc_dealloc(ip, 0);
}

/**
 * gfs2_write_calc_reserv - calculate number of blocks needed to write to a file
 * @ip: the file
 * @len: the number of bytes to be written to the file
 * @data_blocks: returns the number of data blocks required
 * @ind_blocks: returns the number of indirect blocks required
 *
 */

void gfs2_write_calc_reserv(struct gfs2_inode *ip, unsigned int len,
			    unsigned int *data_blocks, unsigned int *ind_blocks)
{
	struct gfs2_sbd *sdp = GFS2_SB(&ip->i_inode);
	unsigned int tmp;

	if (gfs2_is_dir(ip)) {
		*data_blocks = DIV_ROUND_UP(len, sdp->sd_jbsize) + 2;
		*ind_blocks = 3 * (sdp->sd_max_jheight - 1);
	} else {
		*data_blocks = (len >> sdp->sd_sb.sb_bsize_shift) + 3;
		*ind_blocks = 3 * (sdp->sd_max_height - 1);
	}

	for (tmp = *data_blocks; tmp > sdp->sd_diptrs;) {
		tmp = DIV_ROUND_UP(tmp, sdp->sd_inptrs);
		*ind_blocks += tmp;
	}
}

/**
 * gfs2_write_alloc_required - figure out if a write will require an allocation
 * @ip: the file being written to
 * @offset: the offset to write to
 * @len: the number of bytes being written
 * @alloc_required: set to 1 if an alloc is required, 0 otherwise
 *
 * Returns: errno
 */

int gfs2_write_alloc_required(struct gfs2_inode *ip, u64 offset,
			      unsigned int len, int *alloc_required)
{
	struct gfs2_sbd *sdp = GFS2_SB(&ip->i_inode);
	u64 lblock, lblock_stop, dblock;
	u32 extlen;
	int new = 0;
	int error = 0;

	*alloc_required = 0;

	if (!len)
		return 0;

	if (gfs2_is_stuffed(ip)) {
		if (offset + len >
		    sdp->sd_sb.sb_bsize - sizeof(struct gfs2_dinode))
			*alloc_required = 1;
		return 0;
	}

	if (gfs2_is_dir(ip)) {
		unsigned int bsize = sdp->sd_jbsize;
		lblock = offset;
		do_div(lblock, bsize);
		lblock_stop = offset + len + bsize - 1;
		do_div(lblock_stop, bsize);
	} else {
		unsigned int shift = sdp->sd_sb.sb_bsize_shift;
		lblock = offset >> shift;
		lblock_stop = (offset + len + sdp->sd_sb.sb_bsize - 1) >> shift;
	}

	for (; lblock < lblock_stop; lblock += extlen) {
		error = gfs2_extent_map(&ip->i_inode, lblock, &new, &dblock, &extlen);
		if (error)
			return error;

		if (!dblock) {
			*alloc_required = 1;
			return 0;
		}
	}

	return 0;
}