Date:	Fri, 20 Nov 2009 20:38:19 +0100
From:	Joern Engel <joern@...fs.org>
To:	linux-kernel@...r.kernel.org, linux-fsdevel@...r.kernel.org,
	linux-mtd@...ts.infradead.org
Subject: [PATCH 14/17] [LogFS] super.c

---
 fs/logfs/super.c                    |  634 ++++++++++

diff --git a/fs/logfs/super.c b/fs/logfs/super.c
new file mode 100644
index 0000000..d128a2c
--- /dev/null
+++ b/fs/logfs/super.c
@@ -0,0 +1,634 @@
+/*
+ * fs/logfs/super.c
+ *
+ * As should be obvious for Linux kernel code, license is GPLv2
+ *
+ * Copyright (c) 2005-2008 Joern Engel <joern@...fs.org>
+ *
+ * Generally contains mount/umount code and also serves as a dump area for
+ * any functions that don't fit elsewhere and neither justify a file of their
+ * own.
+ */
+#include "logfs.h"
+#include <linux/bio.h>
+#include <linux/mtd/mtd.h>
+#include <linux/statfs.h>
+#include <linux/buffer_head.h>
+
+static DEFINE_MUTEX(emergency_mutex);
+static struct page *emergency_page;
+
+struct page *emergency_read_begin(struct address_space *mapping, pgoff_t index)
+{
+	filler_t *filler = (filler_t *)mapping->a_ops->readpage;
+	struct page *page;
+	int err;
+
+	page = read_cache_page(mapping, index, filler, NULL);
+	if (page)
+		return page;
+
+	/* No more pages available, switch to emergency page */
+	printk(KERN_INFO"Logfs: Using emergency page\n");
+	mutex_lock(&emergency_mutex);
+	err = filler(NULL, emergency_page);
+	if (err) {
+		mutex_unlock(&emergency_mutex);
+		printk(KERN_EMERG"Logfs: Error reading emergency page\n");
+		return ERR_PTR(err);
+	}
+	return emergency_page;
+}
+
+void emergency_read_end(struct page *page)
+{
+	if (page == emergency_page)
+		mutex_unlock(&emergency_mutex);
+	else
+		page_cache_release(page);
+}
+
+static void dump_segfile(struct super_block *sb)
+{
+	struct logfs_super *super = logfs_super(sb);
+	struct logfs_segment_entry se;
+	u32 segno;
+
+	for (segno = 0; segno < super->s_no_segs; segno++) {
+		logfs_get_segment_entry(sb, segno, &se);
+		printk("%3x: %6x %8x", segno, be32_to_cpu(se.ec_level),
+				be32_to_cpu(se.valid));
+		if (++segno < super->s_no_segs) {
+			logfs_get_segment_entry(sb, segno, &se);
+			printk(" %6x %8x", be32_to_cpu(se.ec_level),
+					be32_to_cpu(se.valid));
+		}
+		if (++segno < super->s_no_segs) {
+			logfs_get_segment_entry(sb, segno, &se);
+			printk(" %6x %8x", be32_to_cpu(se.ec_level),
+					be32_to_cpu(se.valid));
+		}
+		if (++segno < super->s_no_segs) {
+			logfs_get_segment_entry(sb, segno, &se);
+			printk(" %6x %8x", be32_to_cpu(se.ec_level),
+					be32_to_cpu(se.valid));
+		}
+		printk("\n");
+	}
+}
+
+/*
+ * logfs_crash_dump - dump debug information to device
+ *
+ * The LogFS superblock only occupies part of a segment.  This function will
+ * write as much debug information as it can gather into the spare space.
+ */
+void logfs_crash_dump(struct super_block *sb)
+{
+	dump_segfile(sb);
+}
+
+/*
+ * TODO: move to lib/string.c
+ */
+/**
+ * memchr_inv - Find a character in an area of memory.
+ * @s: The memory area
+ * @c: The byte to search for
+ * @n: The size of the area.
+ *
+ * returns the address of the first character other than @c, or %NULL
+ * if the whole buffer contains just @c.
+ */
+void *memchr_inv(const void *s, int c, size_t n)
+{
+	const unsigned char *p = s;
+	while (n-- != 0)
+		if ((unsigned char)c != *p++)
+			return (void *)(p - 1);
+
+	return NULL;
+}
+
+/*
+ * FIXME: There should be a reserve for root, similar to ext2.
+ */
+int logfs_statfs(struct dentry *dentry, struct kstatfs *stats)
+{
+	struct super_block *sb = dentry->d_sb;
+	struct logfs_super *super = logfs_super(sb);
+
+	stats->f_type		= LOGFS_MAGIC_U32;
+	stats->f_bsize		= sb->s_blocksize;
+	stats->f_blocks		= super->s_size >> LOGFS_BLOCK_BITS >> 3;
+	stats->f_bfree		= super->s_free_bytes >> sb->s_blocksize_bits;
+	stats->f_bavail		= super->s_free_bytes >> sb->s_blocksize_bits;
+	stats->f_files		= 0;
+	stats->f_ffree		= 0;
+	stats->f_namelen	= LOGFS_MAX_NAMELEN;
+	return 0;
+}
+
+static int logfs_sb_set(struct super_block *sb, void *_super)
+{
+	struct logfs_super *super = _super;
+
+	sb->s_fs_info = super;
+	sb->s_mtd = super->s_mtd;
+	sb->s_bdev = super->s_bdev;
+	return 0;
+}
+
+static int logfs_sb_test(struct super_block *sb, void *_super)
+{
+	struct logfs_super *super = _super;
+	struct mtd_info *mtd = super->s_mtd;
+
+	if (mtd && sb->s_mtd == mtd)
+		return 1;
+	if (super->s_bdev && sb->s_bdev == super->s_bdev)
+		return 1;
+	return 0;
+}
+
+static void set_segment_header(struct logfs_segment_header *sh, u8 type,
+		u8 level, u32 segno, u32 ec)
+{
+	sh->pad = 0;
+	sh->type = type;
+	sh->level = level;
+	sh->segno = cpu_to_be32(segno);
+	sh->ec = cpu_to_be32(ec);
+	sh->gec = cpu_to_be64(segno);
+	sh->crc = logfs_crc32(sh, LOGFS_SEGMENT_HEADERSIZE, 4);
+}
+
+static void logfs_write_ds(struct super_block *sb, struct logfs_disk_super *ds,
+		u32 segno, u32 ec)
+{
+	struct logfs_super *super = logfs_super(sb);
+	struct logfs_segment_header *sh = &ds->ds_sh;
+	int i;
+
+	memset(ds, 0, sizeof(*ds));
+	set_segment_header(sh, SEG_SUPER, 0, segno, ec);
+
+	ds->ds_ifile_levels	= super->s_ifile_levels;
+	ds->ds_iblock_levels	= super->s_iblock_levels;
+	ds->ds_data_levels	= super->s_data_levels; /* XXX: Remove */
+	ds->ds_segment_shift	= super->s_segshift;
+	ds->ds_block_shift	= sb->s_blocksize_bits;
+	ds->ds_write_shift	= super->s_writeshift;
+	ds->ds_filesystem_size	= cpu_to_be64(super->s_size);
+	ds->ds_segment_size	= cpu_to_be32(super->s_segsize);
+	ds->ds_bad_seg_reserve	= cpu_to_be32(super->s_bad_seg_reserve);
+	ds->ds_feature_incompat	= cpu_to_be64(super->s_feature_incompat);
+	ds->ds_feature_ro_compat= cpu_to_be64(super->s_feature_ro_compat);
+	ds->ds_feature_compat	= cpu_to_be64(super->s_feature_compat);
+	ds->ds_feature_flags	= cpu_to_be64(super->s_feature_flags);
+	ds->ds_root_reserve	= cpu_to_be64(super->s_root_reserve);
+	ds->ds_speed_reserve	= cpu_to_be64(super->s_speed_reserve);
+	journal_for_each(i)
+		ds->ds_journal_seg[i] = cpu_to_be32(super->s_journal_seg[i]);
+	ds->ds_magic		= cpu_to_be64(LOGFS_MAGIC);
+	ds->ds_crc = logfs_crc32(ds, sizeof(*ds),
+			LOGFS_SEGMENT_HEADERSIZE + 12);
+}
+
+static int write_one_sb(struct super_block *sb,
+		struct page *(*find_sb)(struct super_block *sb, u64 *ofs))
+{
+	struct logfs_super *super = logfs_super(sb);
+	struct logfs_disk_super *ds;
+	struct logfs_segment_entry se;
+	struct page *page;
+	u64 ofs;
+	u32 ec, segno;
+	int err;
+
+	page = find_sb(sb, &ofs);
+	if (!page)
+		return -EIO;
+	ds = page_address(page);
+	segno = seg_no(sb, ofs);
+	logfs_get_segment_entry(sb, segno, &se);
+	ec = be32_to_cpu(se.ec_level) >> 4;
+	ec++;
+	logfs_set_segment_erased(sb, segno, ec, 0);
+	logfs_write_ds(sb, ds, segno, ec);
+	err = super->s_devops->write_sb(sb, page);
+	page_cache_release(page);
+	return err;
+}
+
+int logfs_write_sb(struct super_block *sb)
+{
+	struct logfs_super *super = logfs_super(sb);
+	int err;
+
+	/* First superblock */
+	err = write_one_sb(sb, super->s_devops->find_first_sb);
+	if (err)
+		return err;
+
+	/* Last superblock */
+	err = write_one_sb(sb, super->s_devops->find_last_sb);
+	if (err)
+		return err;
+	return 0;
+}
+
+static int ds_cmp(const void *ds0, const void *ds1)
+{
+	size_t len = sizeof(struct logfs_disk_super);
+
+	/* We know the segment headers differ, so ignore them */
+	len -= LOGFS_SEGMENT_HEADERSIZE;
+	ds0 += LOGFS_SEGMENT_HEADERSIZE;
+	ds1 += LOGFS_SEGMENT_HEADERSIZE;
+	return memcmp(ds0, ds1, len);
+}
+
+static int logfs_recover_sb(struct super_block *sb)
+{
+	struct logfs_super *super = logfs_super(sb);
+	struct logfs_disk_super _ds0, *ds0 = &_ds0;
+	struct logfs_disk_super _ds1, *ds1 = &_ds1;
+	int err, valid0, valid1;
+
+	/* read first superblock */
+	err = wbuf_read(sb, super->s_sb_ofs[0], sizeof(*ds0), ds0);
+	if (err)
+		return err;
+	/* read last superblock */
+	err = wbuf_read(sb, super->s_sb_ofs[1], sizeof(*ds1), ds1);
+	if (err)
+		return err;
+	valid0 = logfs_check_ds(ds0) == 0;
+	valid1 = logfs_check_ds(ds1) == 0;
+
+	if (!valid0 && valid1) {
+		printk(KERN_INFO"First superblock is invalid - fixing.\n");
+		return write_one_sb(sb, super->s_devops->find_first_sb);
+	}
+	if (valid0 && !valid1) {
+		printk(KERN_INFO"Last superblock is invalid - fixing.\n");
+		return write_one_sb(sb, super->s_devops->find_last_sb);
+	}
+	if (valid0 && valid1 && ds_cmp(ds0, ds1)) {
+		printk(KERN_INFO"Superblocks don't match - fixing.\n");
+		return write_one_sb(sb, super->s_devops->find_last_sb);
+	}
+	/* If neither is valid now, something's wrong.  Didn't we properly
+	 * check them before?!? */
+	BUG_ON(!valid0 && !valid1);
+	return 0;
+}
+
+static int logfs_make_writeable(struct super_block *sb)
+{
+	int err;
+
+	/* Repair any broken superblock copies */
+	err = logfs_recover_sb(sb);
+	if (err)
+		return err;
+
+	/* Check areas for trailing unaccounted data */
+	err = logfs_check_areas(sb);
+	if (err)
+		return err;
+
+	err = logfs_open_segfile(sb);
+	if (err)
+		return err;
+
+	/* Do one GC pass before any data gets dirtied */
+	logfs_gc_pass(sb);
+
+	/* after all initializations are done, replay the journal
+	 * for rw-mounts, if necessary */
+	err = logfs_replay_journal(sb);
+	if (err)
+		return err;
+
+	return 0;
+}
+
+static int logfs_get_sb_final(struct super_block *sb, struct vfsmount *mnt)
+{
+	struct inode *rootdir;
+	int err;
+
+	/* root dir */
+	rootdir = logfs_iget(sb, LOGFS_INO_ROOT);
+	if (IS_ERR(rootdir))
+		goto fail;
+
+	sb->s_root = d_alloc_root(rootdir);
+	if (!sb->s_root)
+		goto fail;
+
+	/* FIXME: check for read-only mounts */
+	err = logfs_make_writeable(sb);
+	if (err)
+		goto fail2;
+
+	log_super("LogFS: Finished mounting\n");
+	simple_set_mnt(mnt, sb);
+	return 0;
+
+fail2:
+	iput(rootdir);
+fail:
+	iput(logfs_super(sb)->s_master_inode);
+	return -EIO;
+}
+
+int logfs_check_ds(struct logfs_disk_super *ds)
+{
+	struct logfs_segment_header *sh = &ds->ds_sh;
+
+	if (ds->ds_magic != cpu_to_be64(LOGFS_MAGIC))
+		return -EINVAL;
+	if (sh->crc != logfs_crc32(sh, LOGFS_SEGMENT_HEADERSIZE, 4))
+		return -EINVAL;
+	if (ds->ds_crc != logfs_crc32(ds, sizeof(*ds),
+				LOGFS_SEGMENT_HEADERSIZE + 12))
+		return -EINVAL;
+	return 0;
+}
+
+static struct page *find_super_block(struct super_block *sb)
+{
+	struct logfs_super *super = logfs_super(sb);
+	struct page *first, *last;
+
+	first = super->s_devops->find_first_sb(sb, &super->s_sb_ofs[0]);
+	if (!first || IS_ERR(first))
+		return NULL;
+	last = super->s_devops->find_last_sb(sb, &super->s_sb_ofs[1]);
+	if (!last || IS_ERR(first)) {
+		page_cache_release(first);
+		return NULL;
+	}
+
+	if (!logfs_check_ds(page_address(first))) {
+		page_cache_release(last);
+		return first;
+	}
+
+	/* First one didn't work, try the second superblock */
+	if (!logfs_check_ds(page_address(last))) {
+		page_cache_release(first);
+		return last;
+	}
+
+	/* Neither worked, sorry folks */
+	page_cache_release(first);
+	page_cache_release(last);
+	return NULL;
+}
+
+static int __logfs_read_sb(struct super_block *sb)
+{
+	struct logfs_super *super = logfs_super(sb);
+	struct page *page;
+	struct logfs_disk_super *ds;
+	int i;
+
+	page = find_super_block(sb);
+	if (!page)
+		return -EIO;
+
+	ds = page_address(page);
+	super->s_size = be64_to_cpu(ds->ds_filesystem_size);
+	super->s_root_reserve = be64_to_cpu(ds->ds_root_reserve);
+	super->s_speed_reserve = be64_to_cpu(ds->ds_speed_reserve);
+	super->s_bad_seg_reserve = be32_to_cpu(ds->ds_bad_seg_reserve);
+	super->s_segsize = 1 << ds->ds_segment_shift;
+	super->s_segmask = (1 << ds->ds_segment_shift) - 1;
+	super->s_segshift = ds->ds_segment_shift;
+	sb->s_blocksize = 1 << ds->ds_block_shift;
+	sb->s_blocksize_bits = ds->ds_block_shift;
+	super->s_writesize = 1 << ds->ds_write_shift;
+	super->s_writeshift = ds->ds_write_shift;
+	super->s_no_segs = super->s_size >> super->s_segshift;
+	super->s_no_blocks = super->s_segsize >> sb->s_blocksize_bits;
+	super->s_feature_incompat = be64_to_cpu(ds->ds_feature_incompat);
+	super->s_feature_ro_compat = be64_to_cpu(ds->ds_feature_ro_compat);
+	super->s_feature_compat = be64_to_cpu(ds->ds_feature_compat);
+	super->s_feature_flags = be64_to_cpu(ds->ds_feature_flags);
+
+	journal_for_each(i)
+		super->s_journal_seg[i] = be32_to_cpu(ds->ds_journal_seg[i]);
+
+	super->s_ifile_levels = ds->ds_ifile_levels;
+	super->s_iblock_levels = ds->ds_iblock_levels;
+	super->s_data_levels = ds->ds_data_levels;
+	super->s_total_levels = super->s_ifile_levels + super->s_iblock_levels
+		+ super->s_data_levels;
+	page_cache_release(page);
+	return 0;
+}
+
+static int logfs_read_sb(struct super_block *sb)
+{
+	struct logfs_super *super = logfs_super(sb);
+	int ret;
+
+	super->s_btree_pool = mempool_create(32, btree_alloc, btree_free, NULL);
+	if (!super->s_btree_pool)
+		return -ENOMEM;
+
+	btree_init_mempool64(&super->s_shadow_tree.new, super->s_btree_pool);
+	btree_init_mempool64(&super->s_shadow_tree.old, super->s_btree_pool);
+
+	ret = logfs_init_mapping(sb);
+	if (ret)
+		return ret;
+
+	ret = __logfs_read_sb(sb);
+	if (ret)
+		return ret;
+
+	mutex_init(&super->s_dirop_mutex);
+	mutex_init(&super->s_object_alias_mutex);
+	INIT_LIST_HEAD(&super->s_freeing_list);
+
+	ret = logfs_init_rw(sb);
+	if (ret)
+		return ret;
+
+	ret = logfs_init_areas(sb);
+	if (ret)
+		return ret;
+
+	ret = logfs_init_gc(sb);
+	if (ret)
+		return ret;
+
+	ret = logfs_init_journal(sb);
+	if (ret)
+		return ret;
+
+	return 0;
+}
+
+static void logfs_kill_sb(struct super_block *sb)
+{
+	struct logfs_super *super = logfs_super(sb);
+
+	log_super("LogFS: Start unmounting\n");
+	/* Alias entries slow down mount, so evict as many as possible */
+	sync_filesystem(sb);
+	logfs_write_anchor(super->s_master_inode);
+
+	/*
+	 * From this point on alias entries are simply dropped - and any
+	 * writes to the object store are considered bugs.
+	 */
+	super->s_flags |= LOGFS_SB_FLAG_SHUTDOWN;
+	log_super("LogFS: Now in shutdown\n");
+	generic_shutdown_super(sb);
+
+	BUG_ON(super->s_dirty_used_bytes || super->s_dirty_free_bytes);
+
+	logfs_cleanup_gc(sb);
+	logfs_cleanup_journal(sb);
+	logfs_cleanup_areas(sb);
+	logfs_cleanup_rw(sb);
+	super->s_devops->put_device(sb);
+	mempool_destroy(super->s_btree_pool);
+	mempool_destroy(super->s_alias_pool);
+	kfree(super);
+	log_super("LogFS: Finished unmounting\n");
+}
+
+int logfs_get_sb_device(struct file_system_type *type, int flags,
+		struct mtd_info *mtd, struct block_device *bdev,
+		const struct logfs_device_ops *devops, struct vfsmount *mnt)
+{
+	struct logfs_super *super;
+	struct super_block *sb;
+	int err = -ENOMEM;
+	static int mount_count;
+
+	log_super("LogFS: Start mount %x\n", mount_count++);
+	super = kzalloc(sizeof(*super), GFP_KERNEL);
+	if (!super)
+		goto err0;
+
+	super->s_mtd	= mtd;
+	super->s_bdev	= bdev;
+	err = -EINVAL;
+	sb = sget(type, logfs_sb_test, logfs_sb_set, super);
+	if (IS_ERR(sb))
+		goto err0;
+
+	if (sb->s_root) {
+		/* Device is already in use */
+		err = 0;
+		simple_set_mnt(mnt, sb);
+		goto err0;
+	}
+
+	super->s_devops = devops;
+
+	/*
+	 * sb->s_maxbytes is limited to 8TB.  On 32bit systems, the page cache
+	 * only covers 16TB and the upper 8TB are used for indirect blocks.
+	 * On 64bit system we could bump up the limit, but that would make
+	 * the filesystem incompatible with 32bit systems.
+	 */
+	sb->s_maxbytes	= (1ull << 43) - 1;
+	sb->s_op	= &logfs_super_operations;
+	sb->s_flags	= flags | MS_NOATIME;
+
+	err = logfs_read_sb(sb);
+	if (err)
+		goto err1;
+
+	sb->s_flags |= MS_ACTIVE;
+	err = logfs_get_sb_final(sb, mnt);
+	if (err)
+		goto err1;
+	return 0;
+
+err1:
+	up_write(&sb->s_umount);
+	deactivate_super(sb);
+	return err;
+err0:
+	kfree(super);
+	//devops->put_device(sb);
+	return err;
+}
+
+static int logfs_get_sb(struct file_system_type *type, int flags,
+		const char *devname, void *data, struct vfsmount *mnt)
+{
+	ulong mtdnr;
+
+	if (!devname)
+		return logfs_get_sb_bdev(type, flags, devname, mnt);
+	if (strncmp(devname, "mtd", 3))
+		return logfs_get_sb_bdev(type, flags, devname, mnt);
+
+	{
+		char *garbage;
+		mtdnr = simple_strtoul(devname+3, &garbage, 0);
+		if (*garbage)
+			return -EINVAL;
+	}
+
+	return logfs_get_sb_mtd(type, flags, mtdnr, mnt);
+}
+
+static struct file_system_type logfs_fs_type = {
+	.owner		= THIS_MODULE,
+	.name		= "logfs",
+	.get_sb		= logfs_get_sb,
+	.kill_sb	= logfs_kill_sb,
+	.fs_flags	= FS_REQUIRES_DEV,
+
+};
+
+static int __init logfs_init(void)
+{
+	int ret;
+
+	emergency_page = alloc_pages(GFP_KERNEL, 0);
+	if (!emergency_page)
+		return -ENOMEM;
+
+	ret = logfs_compr_init();
+	if (ret)
+		goto out1;
+
+	ret = logfs_init_inode_cache();
+	if (ret)
+		goto out2;
+
+	return register_filesystem(&logfs_fs_type);
+out2:
+	logfs_compr_exit();
+out1:
+	__free_pages(emergency_page, 0);
+	return ret;
+}
+
+static void __exit logfs_exit(void)
+{
+	unregister_filesystem(&logfs_fs_type);
+	logfs_destroy_inode_cache();
+	logfs_compr_exit();
+	__free_pages(emergency_page, 0);
+}
+
+module_init(logfs_init);
+module_exit(logfs_exit);
+
+MODULE_LICENSE("GPL v2");
+MODULE_AUTHOR("Joern Engel <joern@...fs.org>");
+MODULE_DESCRIPTION("scalable flash filesystem");
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