Message-ID: <20070603184850.GO8952@lazybastard.org>
Date:	Sun, 3 Jun 2007 20:48:51 +0200
From:	Jörn Engel <joern@...ybastard.org>
To:	linux-fsdevel@...r.kernel.org, linux-kernel@...r.kernel.org,
	linux-mtd@...ts.infradead.org
Cc:	akpm@...l.org, Sam Ravnborg <sam@...nborg.org>,
	John Stoffel <john@...ffel.org>,
	David Woodhouse <dwmw2@...radead.org>,
	Jamie Lokier <jamie@...reable.org>,
	Artem Bityutskiy <dedekind@...radead.org>,
	CaT <cat@....com.au>, Jan Engelhardt <jengelh@...ux01.gwdg.de>,
	Evgeniy Polyakov <johnpol@....mipt.ru>,
	David Weinehall <tao@....umu.se>,
	Arnd Bergmann <arnd@...db.de>, Willy Tarreau <w@....eu>,
	Kyle Moffett <mrmacman_g4@....com>,
	Dongjun Shin <djshin90@...il.com>, Pavel Machek <pavel@....cz>,
	Bill Davidsen <davidsen@....com>,
	Thomas Gleixner <tglx@...utronix.de>,
	Albert Cahalan <acahalan@...il.com>,
	Pekka Enberg <penberg@...helsinki.fi>,
	Roland Dreier <rdreier@...co.com>,
	Ondrej Zajicek <santiago@...reenet.org>,
	Ulisses Furquim <ulissesf@...il.com>
Subject: [Patch 14/18] fs/logfs/segment.c

--- /dev/null	2007-03-13 19:15:28.862769062 +0100
+++ linux-2.6.21logfs/fs/logfs/segment.c	2007-06-03 19:18:57.000000000 +0200
@@ -0,0 +1,524 @@
+/*
+ * fs/logfs/segment.c	- Handling the Object Store
+ *
+ * As should be obvious for Linux kernel code, license is GPLv2
+ *
+ * Copyright (c) 2005-2007 Joern Engel
+ *
+ * Object store or ostore makes up the complete device with exception of
+ * the superblock and journal areas.  Apart from its own metadata it stores
+ * three kinds of objects: inodes, dentries and blocks, both data and indirect.
+ */
+#include "logfs.h"
+
+/* FIXME: combine with per-sb journal variant */
+static unsigned char compressor_buf[LOGFS_MAX_OBJECTSIZE];
+static DEFINE_MUTEX(compr_mutex);
+
+int logfs_erase_segment(struct super_block *sb, u32 index)
+{
+	struct logfs_super *super = logfs_super(sb);
+
+	super->s_gec++;
+
+	return super->s_devops->erase(sb, (u64)index << super->s_segshift, super->s_segsize);
+}
+
+static s32 __logfs_get_free_bytes(struct logfs_area *area, u64 ino, u64 pos,
+		size_t bytes)
+{
+	s32 ofs;
+	int ret;
+
+	ret = logfs_open_area(area);
+	BUG_ON(ret>0);
+	if (ret)
+		return ret;
+
+	ofs = area->a_used_bytes;
+	area->a_used_bytes += bytes;
+	BUG_ON(area->a_used_bytes >= logfs_super(area->a_sb)->s_segsize);
+
+	return dev_ofs(area->a_sb, area->a_segno, ofs);
+}
+
+static void __logfs_set_blocks(struct inode *inode)
+{
+	struct super_block *sb = inode->i_sb;
+	struct logfs_inode *li = logfs_inode(inode);
+
+	inode->i_blocks = ULONG_MAX;
+	if (li->li_used_bytes >> sb->s_blocksize_bits < ULONG_MAX)
+		inode->i_blocks = li->li_used_bytes >> sb->s_blocksize_bits;
+}
+
+void logfs_set_blocks(struct inode *inode, u64 bytes)
+{
+	struct logfs_inode *li = logfs_inode(inode);
+
+	li->li_used_bytes = bytes;
+	__logfs_set_blocks(inode);
+}
+
+static void logfs_consume_bytes(struct inode *inode, int bytes)
+{
+	struct logfs_super *super = logfs_super(inode->i_sb);
+	struct logfs_inode *li = logfs_inode(inode);
+
+	BUG_ON(li->li_used_bytes + bytes < bytes);
+	super->s_free_bytes	-= bytes;
+	super->s_used_bytes	+= bytes;
+	li->li_used_bytes	+= bytes;
+	__logfs_set_blocks(inode);
+}
+
+static void logfs_remove_bytes(struct inode *inode, int bytes)
+{
+	struct logfs_super *super = logfs_super(inode->i_sb);
+	struct logfs_inode *li = logfs_inode(inode);
+
+	BUG_ON(li->li_used_bytes < bytes);
+	super->s_free_bytes	+= bytes;
+	super->s_used_bytes	-= bytes;
+	li->li_used_bytes	-= bytes;
+	__logfs_set_blocks(inode);
+}
+
+static int buf_write(struct logfs_area *area, u64 ofs, void *data, size_t len)
+{
+	struct super_block *sb = area->a_sb;
+	struct logfs_super *super = logfs_super(sb);
+	long write_mask = super->s_writesize - 1;
+	u64 buf_start;
+	size_t space, buf_ofs;
+	int err;
+
+	buf_ofs = (long)ofs & write_mask;
+	if (buf_ofs) {
+		/* buf already used - fill it */
+		space = super->s_writesize - buf_ofs;
+		if (len < space) {
+			/* not enough to fill it - just copy */
+			memcpy(area->a_wbuf + buf_ofs, data, len);
+			return 0;
+		}
+		/* enough data to fill and flush the buffer */
+		memcpy(area->a_wbuf + buf_ofs, data, space);
+		buf_start = ofs & ~write_mask;
+		err = super->s_devops->write(sb, buf_start, super->s_writesize, area->a_wbuf);
+		if (err)
+			return err;
+		ofs += space;
+		data += space;
+		len -= space;
+	}
+
+	/* write complete hunks */
+	space = len & ~write_mask;
+	if (space) {
+		err = super->s_devops->write(sb, ofs, space, data);
+		if (err)
+			return err;
+		ofs += space;
+		data += space;
+		len -= space;
+	}
+
+	/* store anything remaining in wbuf */
+	if (len)
+		memcpy(area->a_wbuf, data, len);
+	return 0;
+}
+
+static int adj_level(u64 ino, int level)
+{
+	BUG_ON(level >= LOGFS_MAX_LEVELS);
+
+	if (ino == LOGFS_INO_MASTER) {
+		/* ifile has seperate areas */
+		level += LOGFS_MAX_LEVELS;
+	}
+	return level;
+}
+
+static struct logfs_area *get_area(struct super_block *sb, int level)
+{
+	return logfs_super(sb)->s_area[level];
+}
+
+static s64 __logfs_segment_write(struct inode *inode, void *buf, u64 pos,
+		int level, int alloc, int len, int compr)
+{
+	struct logfs_area *area;
+	struct super_block *sb = inode->i_sb;
+	u64 ofs;
+	u64 ino = inode->i_ino;
+	int err;
+	struct logfs_object_header h;
+
+	h.crc	= cpu_to_be32(0xcccccccc);
+	h.len	= cpu_to_be16(len);
+	h.type	= OBJ_BLOCK;
+	h.compr	= compr;
+	h.ino	= cpu_to_be64(inode->i_ino);
+	h.pos	= cpu_to_be64(pos);
+
+	level = adj_level(ino, level);
+	area = get_area(sb, level);
+	ofs = __logfs_get_free_bytes(area, ino, pos, len + LOGFS_HEADERSIZE);
+	LOGFS_BUG_ON(ofs <= 0, sb);
+
+	err = buf_write(area, ofs, &h, sizeof(h));
+	if (!err)
+		err = buf_write(area, ofs + LOGFS_HEADERSIZE, buf, len);
+	BUG_ON(err);
+	if (err)
+		return err;
+	if (alloc) {
+		int acc_len = (level==0) ? len : sb->s_blocksize;
+		logfs_consume_bytes(inode, acc_len + LOGFS_HEADERSIZE);
+	}
+
+	/* FIXME merge with open_area */
+	logfs_close_area(area);
+
+	return ofs;
+}
+
+s64 logfs_segment_write(struct inode *inode, void *buf, u64 pos, int level,
+		int alloc)
+{
+	int bs = inode->i_sb->s_blocksize;
+	int compr_len;
+	s64 ofs;
+
+	if (level != 0) {
+		/* temporary disable compression for indirect blocks */
+		return __logfs_segment_write(inode, buf, pos, level, alloc, bs,
+				COMPR_NONE);
+	}
+
+	mutex_lock(&compr_mutex);
+	compr_len = logfs_compress(buf, compressor_buf, bs, bs);
+
+	if (compr_len >= 0) {
+		ofs = __logfs_segment_write(inode, compressor_buf, pos, level,
+				alloc, compr_len, COMPR_ZLIB);
+	} else {
+		ofs = __logfs_segment_write(inode, buf, pos, level, alloc, bs,
+				COMPR_NONE);
+	}
+	mutex_unlock(&compr_mutex);
+	return ofs;
+}
+
+/* FIXME: all this mess should get replaced by using the page cache */
+static void fixup_from_wbuf(struct super_block *sb, struct logfs_area *area,
+		void *read, u64 ofs, size_t readlen)
+{
+	struct logfs_super *super = logfs_super(sb);
+	u32 read_start = ofs & (super->s_segsize - 1);
+	u32 read_end = read_start + readlen;
+	u32 writemask = super->s_writesize - 1;
+	u32 buf_start = area->a_used_bytes & ~writemask;
+	u32 buf_end = area->a_used_bytes;
+	void *buf = area->a_wbuf;
+	size_t buflen = buf_end - buf_start;
+
+	if (read_end < buf_start)
+		return;
+	if ((ofs & (super->s_segsize - 1)) >= area->a_used_bytes) {
+		memset(read, 0xff, readlen);
+		return;
+	}
+
+	if (buf_start > read_start) {
+		read += buf_start - read_start;
+		readlen -= buf_start - read_start;
+	} else {
+		buf += read_start - buf_start;
+		buflen -= read_start - buf_start;
+	}
+	memcpy(read, buf, min(readlen, buflen));
+	if (buflen < readlen)
+		memset(read + buflen, 0xff, readlen - buflen);
+}
+
+int wbuf_read(struct super_block *sb, u64 ofs, size_t len, void *buf)
+{
+	struct logfs_super *super = logfs_super(sb);
+	struct logfs_area *area;
+	u32 segno = ofs >> super->s_segshift;
+	int i, err;
+
+	err = super->s_devops->read(sb, ofs, len, buf);
+	if (err)
+		return err;
+
+	for (i=0; i<LOGFS_NO_AREAS; i++) {
+		area = super->s_area[i];
+		if (area->a_segno == segno) {
+			fixup_from_wbuf(sb, area, buf, ofs, len);
+			break;
+		}
+	}
+	return 0;
+}
+
+int logfs_segment_read(struct super_block *sb, void *buf, u64 ofs)
+{
+	struct logfs_object_header *h;
+	u16 len;
+	int err, bs = sb->s_blocksize;
+
+	mutex_lock(&compr_mutex);
+	err = wbuf_read(sb, ofs, bs + LOGFS_HEADERSIZE, compressor_buf);
+	if (err)
+		goto out;
+	h = (void*)compressor_buf;
+	len = be16_to_cpu(h->len);
+
+	switch (h->compr) {
+	case COMPR_NONE:
+		memcpy(buf, compressor_buf + LOGFS_HEADERSIZE, bs);
+		break;
+	case COMPR_ZLIB:
+		err = logfs_uncompress(compressor_buf + LOGFS_HEADERSIZE, buf,
+				len, bs);
+		BUG_ON(err);
+		break;
+	default:
+		LOGFS_BUG(sb);
+	}
+out:
+	mutex_unlock(&compr_mutex);
+	return err;
+}
+
+static u64 logfs_block_mask[] = {
+	~0,
+	~(I1_BLOCKS-1),
+	~(I2_BLOCKS-1),
+	~(I3_BLOCKS-1)
+};
+
+/*
+ * The "position" of indirect blocks is ambiguous.  It can be the position
+ * of any data block somewhere behind this indirect block.  So we need to
+ * normalize the positions through logfs_block_mask[level] before comparing.
+ */
+static void check_pos(struct super_block *sb, u64 pos1, u64 pos2, int level)
+{
+	LOGFS_BUG_ON(	(pos1 & logfs_block_mask[level]) !=
+			(pos2 & logfs_block_mask[level]), sb);
+}
+
+int logfs_segment_delete(struct inode *inode, u64 ofs, u64 pos, int level)
+{
+	struct super_block *sb = inode->i_sb;
+	struct logfs_object_header *h;
+	u16 len;
+	int err;
+
+
+	mutex_lock(&compr_mutex);
+	err = wbuf_read(sb, ofs, LOGFS_MAX_OBJECTSIZE, compressor_buf);
+	LOGFS_BUG_ON(err, sb);
+	h = (void*)compressor_buf;
+	len = be16_to_cpu(h->len);
+	check_pos(sb, pos, be64_to_cpu(h->pos), level);
+	mutex_unlock(&compr_mutex);
+
+	level = adj_level(inode->i_ino, level);
+	len = (level==0) ? len : sb->s_blocksize;
+	logfs_remove_bytes(inode, len + sizeof(*h));
+	return 0;
+}
+
+int logfs_open_area(struct logfs_area *area)
+{
+	size_t writesize = logfs_super(area->a_sb)->s_writesize;
+
+	if (area->a_is_open)
+		return 0;
+
+	area->a_ops->get_free_segment(area);
+	area->a_used_objects = 0;
+	area->a_used_bytes = 0;
+	area->a_ops->get_erase_count(area);
+
+	if (area->a_wbuf)
+		memset(area->a_wbuf, 0, writesize);
+	area->a_is_open = 1;
+
+	return area->a_ops->erase_segment(area);
+}
+
+void logfs_close_area(struct logfs_area *area)
+{
+	if (!area->a_is_open)
+		return;
+
+	area->a_ops->finish_area(area);
+}
+
+/*
+ * Pick a free segment to be used for this area.  Effectively takes a
+ * candidate from the free list (not really a candidate anymore).
+ */
+static void ostore_get_free_segment(struct logfs_area *area)
+{
+	struct logfs_super *super = logfs_super(area->a_sb);
+	struct gc_candidate *cand;
+
+	BUG_ON(list_empty(&super->s_free_list));
+
+	cand = list_entry(super->s_free_list.prev, struct gc_candidate, list);
+	list_del(&cand->list);
+	area->a_segno = cand->segno;
+	kfree(cand);
+	super->s_free_count -= 1;
+}
+
+static void ostore_get_erase_count(struct logfs_area *area)
+{
+	struct logfs_segment_header h;
+	int err;
+
+	err = device_read(area->a_sb, area->a_segno, 0, sizeof(h), &h);
+	BUG_ON(err);
+	area->a_erase_count = be32_to_cpu(h.ec) + 1;
+}
+
+static int ostore_erase_segment(struct logfs_area *area)
+{
+	struct logfs_segment_header h;
+	u64 ofs;
+	int err;
+
+	err = logfs_erase_segment(area->a_sb, area->a_segno);
+	if (err)
+		return err;
+
+	h.len = 0;
+	h.type = OBJ_OSTORE;
+	h.level = area->a_level;
+	h.segno = cpu_to_be32(area->a_segno);
+	h.ec = cpu_to_be32(area->a_erase_count);
+	h.gec = cpu_to_be64(logfs_super(area->a_sb)->s_gec);
+	h.crc = logfs_crc32(&h, sizeof(h), 4);
+
+	ofs = dev_ofs(area->a_sb, area->a_segno, 0);
+	area->a_used_bytes = sizeof(h);
+	return buf_write(area, ofs, &h, sizeof(h));
+}
+
+static void flush_buf(struct logfs_area *area)
+{
+	struct super_block *sb = area->a_sb;
+	struct logfs_super *super = logfs_super(sb);
+	u32 used, free;
+	u64 ofs;
+	u32 writemask = super->s_writesize - 1;
+	int err;
+
+	ofs = dev_ofs(sb, area->a_segno, area->a_used_bytes);
+	ofs &= ~writemask;
+	used = area->a_used_bytes & writemask;
+	free = super->s_writesize - area->a_used_bytes;
+	free &= writemask;
+	if (used == 0)
+		return;
+
+	memset(area->a_wbuf + used, 0xff, free);
+	err = super->s_devops->write(sb, ofs, super->s_writesize, area->a_wbuf);
+	LOGFS_BUG_ON(err, sb);
+}
+
+static void ostore_finish_area(struct logfs_area *area)
+{
+	struct super_block *sb = area->a_sb;
+	struct logfs_super *super = logfs_super(sb);
+	u32 remaining = super->s_segsize - area->a_used_bytes;
+	u32 needed = sb->s_blocksize + sizeof(struct logfs_segment_header);
+
+	if (remaining > needed)
+		return;
+
+	flush_buf(area);
+
+	area->a_segno = 0;
+	area->a_is_open = 0;
+}
+
+static const struct logfs_area_ops ostore_area_ops = {
+	.get_free_segment	= ostore_get_free_segment,
+	.get_erase_count	= ostore_get_erase_count,
+	.erase_segment		= ostore_erase_segment,
+	.finish_area		= ostore_finish_area,
+};
+
+static void cleanup_ostore_area(struct logfs_area *area)
+{
+	kfree(area->a_wbuf);
+	kfree(area);
+}
+
+static void *init_ostore_area(struct super_block *sb, int level)
+{
+	struct logfs_area *area;
+	size_t writesize;
+
+	writesize = logfs_super(sb)->s_writesize;
+
+	area = kzalloc(sizeof(*area), GFP_KERNEL);
+	if (!area)
+		return NULL;
+	if (writesize > 1) {
+		area->a_wbuf = kmalloc(writesize, GFP_KERNEL);
+		if (!area->a_wbuf)
+			goto err;
+	}
+
+	area->a_sb = sb;
+	area->a_level = level;
+	area->a_ops = &ostore_area_ops;
+	return area;
+
+err:
+	cleanup_ostore_area(area);
+	return NULL;
+}
+
+int logfs_init_areas(struct super_block *sb)
+{
+	struct logfs_super *super = logfs_super(sb);
+	int i;
+
+	super->s_journal_area = kzalloc(sizeof(struct logfs_area), GFP_KERNEL);
+	if (!super->s_journal_area)
+		return -ENOMEM;
+	super->s_journal_area->a_sb = sb;
+
+	for (i=0; i<LOGFS_NO_AREAS; i++) {
+		super->s_area[i] = init_ostore_area(sb, i);
+		if (!super->s_area[i])
+			goto err;
+	}
+	return 0;
+
+err:
+	for (i--; i>=0; i--)
+		cleanup_ostore_area(super->s_area[i]);
+	kfree(super->s_journal_area);
+	return -ENOMEM;
+}
+
+void logfs_cleanup_areas(struct logfs_super *super)
+{
+	int i;
+
+	for (i=0; i<LOGFS_NO_AREAS; i++)
+		cleanup_ostore_area(super->s_area[i]);
+	kfree(super->s_journal_area);
+}
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