[LogFS] add new flash file system

This is a new flash file system. See
Documentation/filesystems/logfs.txt

Signed-off-by: Joern Engel <joern@logfs.org>

1 files changed, 879 insertions, 0 deletions

diff --git a/fs/logfs/journal.c b/fs/logfs/journal.c
new file mode 100644
index 000000000000..7a023dbba9f8
--- /dev/null
+++ b/fs/logfs/journal.c
@@ -0,0 +1,879 @@
+/*
+ * fs/logfs/journal.c   - journal handling code
+ *
+ * As should be obvious for Linux kernel code, license is GPLv2
+ *
+ * Copyright (c) 2005-2008 Joern Engel <joern@logfs.org>
+ */
+#include "logfs.h"
+
+static void logfs_calc_free(struct super_block *sb)
+{
+        struct logfs_super *super = logfs_super(sb);
+        u64 reserve, no_segs = super->s_no_segs;
+        s64 free;
+        int i;
+
+        /* superblock segments */
+        no_segs -= 2;
+        super->s_no_journal_segs = 0;
+        /* journal */
+        journal_for_each(i)
+                if (super->s_journal_seg[i]) {
+                        no_segs--;
+                        super->s_no_journal_segs++;
+                }
+
+        /* open segments plus one extra per level for GC */
+        no_segs -= 2 * super->s_total_levels;
+
+        free = no_segs * (super->s_segsize - LOGFS_SEGMENT_RESERVE);
+        free -= super->s_used_bytes;
+        /* just a bit extra */
+        free -= super->s_total_levels * 4096;
+
+        /* Bad blocks are 'paid' for with speed reserve - the filesystem
+         * simply gets slower as bad blocks accumulate.  Until the bad blocks
+         * exceed the speed reserve - then the filesystem gets smaller.
+         */
+        reserve = super->s_bad_segments + super->s_bad_seg_reserve;
+        reserve *= super->s_segsize - LOGFS_SEGMENT_RESERVE;
+        reserve = max(reserve, super->s_speed_reserve);
+        free -= reserve;
+        if (free < 0)
+                free = 0;
+
+        super->s_free_bytes = free;
+}
+
+static void reserve_sb_and_journal(struct super_block *sb)
+{
+        struct logfs_super *super = logfs_super(sb);
+        struct btree_head32 *head = &super->s_reserved_segments;
+        int i, err;
+
+        err = btree_insert32(head, seg_no(sb, super->s_sb_ofs[0]), (void *)1,
+                        GFP_KERNEL);
+        BUG_ON(err);
+
+        err = btree_insert32(head, seg_no(sb, super->s_sb_ofs[1]), (void *)1,
+                        GFP_KERNEL);
+        BUG_ON(err);
+
+        journal_for_each(i) {
+                if (!super->s_journal_seg[i])
+                        continue;
+                err = btree_insert32(head, super->s_journal_seg[i], (void *)1,
+                                GFP_KERNEL);
+                BUG_ON(err);
+        }
+}
+
+static void read_dynsb(struct super_block *sb,
+                struct logfs_je_dynsb *dynsb)
+{
+        struct logfs_super *super = logfs_super(sb);
+
+        super->s_gec            = be64_to_cpu(dynsb->ds_gec);
+        super->s_sweeper        = be64_to_cpu(dynsb->ds_sweeper);
+        super->s_victim_ino     = be64_to_cpu(dynsb->ds_victim_ino);
+        super->s_rename_dir     = be64_to_cpu(dynsb->ds_rename_dir);
+        super->s_rename_pos     = be64_to_cpu(dynsb->ds_rename_pos);
+        super->s_used_bytes     = be64_to_cpu(dynsb->ds_used_bytes);
+        super->s_generation     = be32_to_cpu(dynsb->ds_generation);
+}
+
+static void read_anchor(struct super_block *sb,
+                struct logfs_je_anchor *da)
+{
+        struct logfs_super *super = logfs_super(sb);
+        struct inode *inode = super->s_master_inode;
+        struct logfs_inode *li = logfs_inode(inode);
+        int i;
+
+        super->s_last_ino = be64_to_cpu(da->da_last_ino);
+        li->li_flags    = 0;
+        li->li_height   = da->da_height;
+        i_size_write(inode, be64_to_cpu(da->da_size));
+        li->li_used_bytes = be64_to_cpu(da->da_used_bytes);
+
+        for (i = 0; i < LOGFS_EMBEDDED_FIELDS; i++)
+                li->li_data[i] = be64_to_cpu(da->da_data[i]);
+}
+
+static void read_erasecount(struct super_block *sb,
+                struct logfs_je_journal_ec *ec)
+{
+        struct logfs_super *super = logfs_super(sb);
+        int i;
+
+        journal_for_each(i)
+                super->s_journal_ec[i] = be32_to_cpu(ec->ec[i]);
+}
+
+static int read_area(struct super_block *sb, struct logfs_je_area *a)
+{
+        struct logfs_super *super = logfs_super(sb);
+        struct logfs_area *area = super->s_area[a->gc_level];
+        u64 ofs;
+        u32 writemask = ~(super->s_writesize - 1);
+
+        if (a->gc_level >= LOGFS_NO_AREAS)
+                return -EIO;
+        if (a->vim != VIM_DEFAULT)
+                return -EIO; /* TODO: close area and continue */
+
+        area->a_used_bytes = be32_to_cpu(a->used_bytes);
+        area->a_written_bytes = area->a_used_bytes & writemask;
+        area->a_segno = be32_to_cpu(a->segno);
+        if (area->a_segno)
+                area->a_is_open = 1;
+
+        ofs = dev_ofs(sb, area->a_segno, area->a_written_bytes);
+        if (super->s_writesize > 1)
+                logfs_buf_recover(area, ofs, a + 1, super->s_writesize);
+        else
+                logfs_buf_recover(area, ofs, NULL, 0);
+        return 0;
+}
+
+static void *unpack(void *from, void *to)
+{
+        struct logfs_journal_header *jh = from;
+        void *data = from + sizeof(struct logfs_journal_header);
+        int err;
+        size_t inlen, outlen;
+
+        inlen = be16_to_cpu(jh->h_len);
+        outlen = be16_to_cpu(jh->h_datalen);
+
+        if (jh->h_compr == COMPR_NONE)
+                memcpy(to, data, inlen);
+        else {
+                err = logfs_uncompress(data, to, inlen, outlen);
+                BUG_ON(err);
+        }
+        return to;
+}
+
+static int __read_je_header(struct super_block *sb, u64 ofs,
+                struct logfs_journal_header *jh)
+{
+        struct logfs_super *super = logfs_super(sb);
+        size_t bufsize = max_t(size_t, sb->s_blocksize, super->s_writesize)
+                + MAX_JOURNAL_HEADER;
+        u16 type, len, datalen;
+        int err;
+
+        /* read header only */
+        err = wbuf_read(sb, ofs, sizeof(*jh), jh);
+        if (err)
+                return err;
+        type = be16_to_cpu(jh->h_type);
+        len = be16_to_cpu(jh->h_len);
+        datalen = be16_to_cpu(jh->h_datalen);
+        if (len > sb->s_blocksize)
+                return -EIO;
+        if ((type < JE_FIRST) || (type > JE_LAST))
+                return -EIO;
+        if (datalen > bufsize)
+                return -EIO;
+        return 0;
+}
+
+static int __read_je_payload(struct super_block *sb, u64 ofs,
+                struct logfs_journal_header *jh)
+{
+        u16 len;
+        int err;
+
+        len = be16_to_cpu(jh->h_len);
+        err = wbuf_read(sb, ofs + sizeof(*jh), len, jh + 1);
+        if (err)
+                return err;
+        if (jh->h_crc != logfs_crc32(jh, len + sizeof(*jh), 4)) {
+                /* Old code was confused.  It forgot about the header length
+                 * and stopped calculating the crc 16 bytes before the end
+                 * of data - ick!
+                 * FIXME: Remove this hack once the old code is fixed.
+                 */
+                if (jh->h_crc == logfs_crc32(jh, len, 4))
+                        WARN_ON_ONCE(1);
+                else
+                        return -EIO;
+        }
+        return 0;
+}
+
+/*
+ * jh needs to be large enough to hold the complete entry, not just the header
+ */
+static int __read_je(struct super_block *sb, u64 ofs,
+                struct logfs_journal_header *jh)
+{
+        int err;
+
+        err = __read_je_header(sb, ofs, jh);
+        if (err)
+                return err;
+        return __read_je_payload(sb, ofs, jh);
+}
+
+static int read_je(struct super_block *sb, u64 ofs)
+{
+        struct logfs_super *super = logfs_super(sb);
+        struct logfs_journal_header *jh = super->s_compressed_je;
+        void *scratch = super->s_je;
+        u16 type, datalen;
+        int err;
+
+        err = __read_je(sb, ofs, jh);
+        if (err)
+                return err;
+        type = be16_to_cpu(jh->h_type);
+        datalen = be16_to_cpu(jh->h_datalen);
+
+        switch (type) {
+        case JE_DYNSB:
+                read_dynsb(sb, unpack(jh, scratch));
+                break;
+        case JE_ANCHOR:
+                read_anchor(sb, unpack(jh, scratch));
+                break;
+        case JE_ERASECOUNT:
+                read_erasecount(sb, unpack(jh, scratch));
+                break;
+        case JE_AREA:
+                read_area(sb, unpack(jh, scratch));
+                break;
+        case JE_OBJ_ALIAS:
+                err = logfs_load_object_aliases(sb, unpack(jh, scratch),
+                                datalen);
+                break;
+        default:
+                WARN_ON_ONCE(1);
+                return -EIO;
+        }
+        return err;
+}
+
+static int logfs_read_segment(struct super_block *sb, u32 segno)
+{
+        struct logfs_super *super = logfs_super(sb);
+        struct logfs_journal_header *jh = super->s_compressed_je;
+        u64 ofs, seg_ofs = dev_ofs(sb, segno, 0);
+        u32 h_ofs, last_ofs = 0;
+        u16 len, datalen, last_len;
+        int i, err;
+
+        /* search for most recent commit */
+        for (h_ofs = 0; h_ofs < super->s_segsize; h_ofs += sizeof(*jh)) {
+                ofs = seg_ofs + h_ofs;
+                err = __read_je_header(sb, ofs, jh);
+                if (err)
+                        continue;
+                if (jh->h_type != cpu_to_be16(JE_COMMIT))
+                        continue;
+                err = __read_je_payload(sb, ofs, jh);
+                if (err)
+                        continue;
+                len = be16_to_cpu(jh->h_len);
+                datalen = be16_to_cpu(jh->h_datalen);
+                if ((datalen > sizeof(super->s_je_array)) ||
+                                (datalen % sizeof(__be64)))
+                        continue;
+                last_ofs = h_ofs;
+                last_len = datalen;
+                h_ofs += ALIGN(len, sizeof(*jh)) - sizeof(*jh);
+        }
+        /* read commit */
+        if (last_ofs == 0)
+                return -ENOENT;
+        ofs = seg_ofs + last_ofs;
+        log_journal("Read commit from %llx\n", ofs);
+        err = __read_je(sb, ofs, jh);
+        BUG_ON(err); /* We should have caught it in the scan loop already */
+        if (err)
+                return err;
+        /* uncompress */
+        unpack(jh, super->s_je_array);
+        super->s_no_je = last_len / sizeof(__be64);
+        /* iterate over array */
+        for (i = 0; i < super->s_no_je; i++) {
+                err = read_je(sb, be64_to_cpu(super->s_je_array[i]));
+                if (err)
+                        return err;
+        }
+        super->s_journal_area->a_segno = segno;
+        return 0;
+}
+
+static u64 read_gec(struct super_block *sb, u32 segno)
+{
+        struct logfs_segment_header sh;
+        __be32 crc;
+        int err;
+
+        if (!segno)
+                return 0;
+        err = wbuf_read(sb, dev_ofs(sb, segno, 0), sizeof(sh), &sh);
+        if (err)
+                return 0;
+        crc = logfs_crc32(&sh, sizeof(sh), 4);
+        if (crc != sh.crc) {
+                WARN_ON(sh.gec != cpu_to_be64(0xffffffffffffffffull));
+                /* Most likely it was just erased */
+                return 0;
+        }
+        return be64_to_cpu(sh.gec);
+}
+
+static int logfs_read_journal(struct super_block *sb)
+{
+        struct logfs_super *super = logfs_super(sb);
+        u64 gec[LOGFS_JOURNAL_SEGS], max;
+        u32 segno;
+        int i, max_i;
+
+        max = 0;
+        max_i = -1;
+        journal_for_each(i) {
+                segno = super->s_journal_seg[i];
+                gec[i] = read_gec(sb, super->s_journal_seg[i]);
+                if (gec[i] > max) {
+                        max = gec[i];
+                        max_i = i;
+                }
+        }
+        if (max_i == -1)
+                return -EIO;
+        /* FIXME: Try older segments in case of error */
+        return logfs_read_segment(sb, super->s_journal_seg[max_i]);
+}
+
+/*
+ * First search the current segment (outer loop), then pick the next segment
+ * in the array, skipping any zero entries (inner loop).
+ */
+static void journal_get_free_segment(struct logfs_area *area)
+{
+        struct logfs_super *super = logfs_super(area->a_sb);
+        int i;
+
+        journal_for_each(i) {
+                if (area->a_segno != super->s_journal_seg[i])
+                        continue;
+
+                do {
+                        i++;
+                        if (i == LOGFS_JOURNAL_SEGS)
+                                i = 0;
+                } while (!super->s_journal_seg[i]);
+
+                area->a_segno = super->s_journal_seg[i];
+                area->a_erase_count = ++(super->s_journal_ec[i]);
+                log_journal("Journal now at %x (ec %x)\n", area->a_segno,
+                                area->a_erase_count);
+                return;
+        }
+        BUG();
+}
+
+static void journal_get_erase_count(struct logfs_area *area)
+{
+        /* erase count is stored globally and incremented in
+         * journal_get_free_segment() - nothing to do here */
+}
+
+static int journal_erase_segment(struct logfs_area *area)
+{
+        struct super_block *sb = area->a_sb;
+        struct logfs_segment_header sh;
+        u64 ofs;
+        int err;
+
+        err = logfs_erase_segment(sb, area->a_segno);
+        if (err)
+                return err;
+
+        sh.pad = 0;
+        sh.type = SEG_JOURNAL;
+        sh.level = 0;
+        sh.segno = cpu_to_be32(area->a_segno);
+        sh.ec = cpu_to_be32(area->a_erase_count);
+        sh.gec = cpu_to_be64(logfs_super(sb)->s_gec);
+        sh.crc = logfs_crc32(&sh, sizeof(sh), 4);
+
+        /* This causes a bug in segment.c.  Not yet. */
+        //logfs_set_segment_erased(sb, area->a_segno, area->a_erase_count, 0);
+
+        ofs = dev_ofs(sb, area->a_segno, 0);
+        area->a_used_bytes = ALIGN(sizeof(sh), 16);
+        logfs_buf_write(area, ofs, &sh, sizeof(sh));
+        return 0;
+}
+
+static size_t __logfs_write_header(struct logfs_super *super,
+                struct logfs_journal_header *jh, size_t len, size_t datalen,
+                u16 type, u8 compr)
+{
+        jh->h_len       = cpu_to_be16(len);
+        jh->h_type      = cpu_to_be16(type);
+        jh->h_version   = cpu_to_be16(++super->s_last_version);
+        jh->h_datalen   = cpu_to_be16(datalen);
+        jh->h_compr     = compr;
+        jh->h_pad[0]    = 'H';
+        jh->h_pad[1]    = 'A';
+        jh->h_pad[2]    = 'T';
+        jh->h_crc       = logfs_crc32(jh, len + sizeof(*jh), 4);
+        return ALIGN(len, 16) + sizeof(*jh);
+}
+
+static size_t logfs_write_header(struct logfs_super *super,
+                struct logfs_journal_header *jh, size_t datalen, u16 type)
+{
+        size_t len = datalen;
+
+        return __logfs_write_header(super, jh, len, datalen, type, COMPR_NONE);
+}
+
+static inline size_t logfs_journal_erasecount_size(struct logfs_super *super)
+{
+        return LOGFS_JOURNAL_SEGS * sizeof(__be32);
+}
+
+static void *logfs_write_erasecount(struct super_block *sb, void *_ec,
+                u16 *type, size_t *len)
+{
+        struct logfs_super *super = logfs_super(sb);
+        struct logfs_je_journal_ec *ec = _ec;
+        int i;
+
+        journal_for_each(i)
+                ec->ec[i] = cpu_to_be32(super->s_journal_ec[i]);
+        *type = JE_ERASECOUNT;
+        *len = logfs_journal_erasecount_size(super);
+        return ec;
+}
+
+static void account_shadow(void *_shadow, unsigned long _sb, u64 ignore,
+                size_t ignore2)
+{
+        struct logfs_shadow *shadow = _shadow;
+        struct super_block *sb = (void *)_sb;
+        struct logfs_super *super = logfs_super(sb);
+
+        /* consume new space */
+        super->s_free_bytes       -= shadow->new_len;
+        super->s_used_bytes       += shadow->new_len;
+        super->s_dirty_used_bytes -= shadow->new_len;
+
+        /* free up old space */
+        super->s_free_bytes       += shadow->old_len;
+        super->s_used_bytes       -= shadow->old_len;
+        super->s_dirty_free_bytes -= shadow->old_len;
+
+        logfs_set_segment_used(sb, shadow->old_ofs, -shadow->old_len);
+        logfs_set_segment_used(sb, shadow->new_ofs, shadow->new_len);
+
+        log_journal("account_shadow(%llx, %llx, %x) %llx->%llx %x->%x\n",
+                        shadow->ino, shadow->bix, shadow->gc_level,
+                        shadow->old_ofs, shadow->new_ofs,
+                        shadow->old_len, shadow->new_len);
+        mempool_free(shadow, super->s_shadow_pool);
+}
+
+static void account_shadows(struct super_block *sb)
+{
+        struct logfs_super *super = logfs_super(sb);
+        struct inode *inode = super->s_master_inode;
+        struct logfs_inode *li = logfs_inode(inode);
+        struct shadow_tree *tree = &super->s_shadow_tree;
+
+        btree_grim_visitor64(&tree->new, (unsigned long)sb, account_shadow);
+        btree_grim_visitor64(&tree->old, (unsigned long)sb, account_shadow);
+
+        if (li->li_block) {
+                /*
+                 * We never actually use the structure, when attached to the
+                 * master inode.  But it is easier to always free it here than
+                 * to have checks in several places elsewhere when allocating
+                 * it.
+                 */
+                li->li_block->ops->free_block(sb, li->li_block);
+        }
+        BUG_ON((s64)li->li_used_bytes < 0);
+}
+
+static void *__logfs_write_anchor(struct super_block *sb, void *_da,
+                u16 *type, size_t *len)
+{
+        struct logfs_super *super = logfs_super(sb);
+        struct logfs_je_anchor *da = _da;
+        struct inode *inode = super->s_master_inode;
+        struct logfs_inode *li = logfs_inode(inode);
+        int i;
+
+        da->da_height   = li->li_height;
+        da->da_last_ino = cpu_to_be64(super->s_last_ino);
+        da->da_size     = cpu_to_be64(i_size_read(inode));
+        da->da_used_bytes = cpu_to_be64(li->li_used_bytes);
+        for (i = 0; i < LOGFS_EMBEDDED_FIELDS; i++)
+                da->da_data[i] = cpu_to_be64(li->li_data[i]);
+        *type = JE_ANCHOR;
+        *len = sizeof(*da);
+        return da;
+}
+
+static void *logfs_write_dynsb(struct super_block *sb, void *_dynsb,
+                u16 *type, size_t *len)
+{
+        struct logfs_super *super = logfs_super(sb);
+        struct logfs_je_dynsb *dynsb = _dynsb;
+
+        dynsb->ds_gec           = cpu_to_be64(super->s_gec);
+        dynsb->ds_sweeper       = cpu_to_be64(super->s_sweeper);
+        dynsb->ds_victim_ino    = cpu_to_be64(super->s_victim_ino);
+        dynsb->ds_rename_dir    = cpu_to_be64(super->s_rename_dir);
+        dynsb->ds_rename_pos    = cpu_to_be64(super->s_rename_pos);
+        dynsb->ds_used_bytes    = cpu_to_be64(super->s_used_bytes);
+        dynsb->ds_generation    = cpu_to_be32(super->s_generation);
+        *type = JE_DYNSB;
+        *len = sizeof(*dynsb);
+        return dynsb;
+}
+
+static void write_wbuf(struct super_block *sb, struct logfs_area *area,
+                void *wbuf)
+{
+        struct logfs_super *super = logfs_super(sb);
+        struct address_space *mapping = super->s_mapping_inode->i_mapping;
+        u64 ofs;
+        pgoff_t index;
+        int page_ofs;
+        struct page *page;
+
+        ofs = dev_ofs(sb, area->a_segno,
+                        area->a_used_bytes & ~(super->s_writesize - 1));
+        index = ofs >> PAGE_SHIFT;
+        page_ofs = ofs & (PAGE_SIZE - 1);
+
+        page = find_lock_page(mapping, index);
+        BUG_ON(!page);
+        memcpy(wbuf, page_address(page) + page_ofs, super->s_writesize);
+        unlock_page(page);
+}
+
+static void *logfs_write_area(struct super_block *sb, void *_a,
+                u16 *type, size_t *len)
+{
+        struct logfs_super *super = logfs_super(sb);
+        struct logfs_area *area = super->s_area[super->s_sum_index];
+        struct logfs_je_area *a = _a;
+
+        a->vim = VIM_DEFAULT;
+        a->gc_level = super->s_sum_index;
+        a->used_bytes = cpu_to_be32(area->a_used_bytes);
+        a->segno = cpu_to_be32(area->a_segno);
+        if (super->s_writesize > 1)
+                write_wbuf(sb, area, a + 1);
+
+        *type = JE_AREA;
+        *len = sizeof(*a) + super->s_writesize;
+        return a;
+}
+
+static void *logfs_write_commit(struct super_block *sb, void *h,
+                u16 *type, size_t *len)
+{
+        struct logfs_super *super = logfs_super(sb);
+
+        *type = JE_COMMIT;
+        *len = super->s_no_je * sizeof(__be64);
+        return super->s_je_array;
+}
+
+static size_t __logfs_write_je(struct super_block *sb, void *buf, u16 type,
+                size_t len)
+{
+        struct logfs_super *super = logfs_super(sb);
+        void *header = super->s_compressed_je;
+        void *data = header + sizeof(struct logfs_journal_header);
+        ssize_t compr_len, pad_len;
+        u8 compr = COMPR_ZLIB;
+
+        if (len == 0)
+                return logfs_write_header(super, header, 0, type);
+
+        compr_len = logfs_compress(buf, data, len, sb->s_blocksize);
+        if (compr_len < 0 || type == JE_ANCHOR) {
+                BUG_ON(len > sb->s_blocksize);
+                memcpy(data, buf, len);
+                compr_len = len;
+                compr = COMPR_NONE;
+        }
+
+        pad_len = ALIGN(compr_len, 16);
+        memset(data + compr_len, 0, pad_len - compr_len);
+
+        return __logfs_write_header(super, header, compr_len, len, type, compr);
+}
+
+static s64 logfs_get_free_bytes(struct logfs_area *area, size_t *bytes,
+                int must_pad)
+{
+        u32 writesize = logfs_super(area->a_sb)->s_writesize;
+        s32 ofs;
+        int ret;
+
+        ret = logfs_open_area(area, *bytes);
+        if (ret)
+                return -EAGAIN;
+
+        ofs = area->a_used_bytes;
+        area->a_used_bytes += *bytes;
+
+        if (must_pad) {
+                area->a_used_bytes = ALIGN(area->a_used_bytes, writesize);
+                *bytes = area->a_used_bytes - ofs;
+        }
+
+        return dev_ofs(area->a_sb, area->a_segno, ofs);
+}
+
+static int logfs_write_je_buf(struct super_block *sb, void *buf, u16 type,
+                size_t buf_len)
+{
+        struct logfs_super *super = logfs_super(sb);
+        struct logfs_area *area = super->s_journal_area;
+        struct logfs_journal_header *jh = super->s_compressed_je;
+        size_t len;
+        int must_pad = 0;
+        s64 ofs;
+
+        len = __logfs_write_je(sb, buf, type, buf_len);
+        if (jh->h_type == cpu_to_be16(JE_COMMIT))
+                must_pad = 1;
+
+        ofs = logfs_get_free_bytes(area, &len, must_pad);
+        if (ofs < 0)
+                return ofs;
+        logfs_buf_write(area, ofs, super->s_compressed_je, len);
+        super->s_je_array[super->s_no_je++] = cpu_to_be64(ofs);
+        return 0;
+}
+
+static int logfs_write_je(struct super_block *sb,
+                void* (*write)(struct super_block *sb, void *scratch,
+                        u16 *type, size_t *len))
+{
+        void *buf;
+        size_t len;
+        u16 type;
+
+        buf = write(sb, logfs_super(sb)->s_je, &type, &len);
+        return logfs_write_je_buf(sb, buf, type, len);
+}
+
+int write_alias_journal(struct super_block *sb, u64 ino, u64 bix,
+                level_t level, int child_no, __be64 val)
+{
+        struct logfs_super *super = logfs_super(sb);
+        struct logfs_obj_alias *oa = super->s_je;
+        int err = 0, fill = super->s_je_fill;
+
+        log_aliases("logfs_write_obj_aliases #%x(%llx, %llx, %x, %x) %llx\n",
+                        fill, ino, bix, level, child_no, be64_to_cpu(val));
+        oa[fill].ino = cpu_to_be64(ino);
+        oa[fill].bix = cpu_to_be64(bix);
+        oa[fill].val = val;
+        oa[fill].level = (__force u8)level;
+        oa[fill].child_no = cpu_to_be16(child_no);
+        fill++;
+        if (fill >= sb->s_blocksize / sizeof(*oa)) {
+                err = logfs_write_je_buf(sb, oa, JE_OBJ_ALIAS, sb->s_blocksize);
+                fill = 0;
+        }
+
+        super->s_je_fill = fill;
+        return err;
+}
+
+static int logfs_write_obj_aliases(struct super_block *sb)
+{
+        struct logfs_super *super = logfs_super(sb);
+        int err;
+
+        log_journal("logfs_write_obj_aliases: %d aliases to write\n",
+                        super->s_no_object_aliases);
+        super->s_je_fill = 0;
+        err = logfs_write_obj_aliases_pagecache(sb);
+        if (err)
+                return err;
+
+        if (super->s_je_fill)
+                err = logfs_write_je_buf(sb, super->s_je, JE_OBJ_ALIAS,
+                                super->s_je_fill
+                                * sizeof(struct logfs_obj_alias));
+        return err;
+}
+
+/*
+ * Write all journal entries.  The goto logic ensures that all journal entries
+ * are written whenever a new segment is used.  It is ugly and potentially a
+ * bit wasteful, but robustness is more important.  With this we can *always*
+ * erase all journal segments except the one containing the most recent commit.
+ */
+void logfs_write_anchor(struct inode *inode)
+{
+        struct super_block *sb = inode->i_sb;
+        struct logfs_super *super = logfs_super(sb);
+        struct logfs_area *area = super->s_journal_area;
+        int i, err;
+
+        BUG_ON(logfs_super(sb)->s_flags & LOGFS_SB_FLAG_SHUTDOWN);
+        mutex_lock(&super->s_journal_mutex);
+
+        /* Do this first or suffer corruption */
+        logfs_sync_segments(sb);
+        account_shadows(sb);
+
+again:
+        super->s_no_je = 0;
+        for_each_area(i) {
+                if (!super->s_area[i]->a_is_open)
+                        continue;
+                super->s_sum_index = i;
+                err = logfs_write_je(sb, logfs_write_area);
+                if (err)
+                        goto again;
+        }
+        err = logfs_write_obj_aliases(sb);
+        if (err)
+                goto again;
+        err = logfs_write_je(sb, logfs_write_erasecount);
+        if (err)
+                goto again;
+        err = logfs_write_je(sb, __logfs_write_anchor);
+        if (err)
+                goto again;
+        err = logfs_write_je(sb, logfs_write_dynsb);
+        if (err)
+                goto again;
+        /*
+         * Order is imperative.  First we sync all writes, including the
+         * non-committed journal writes.  Then we write the final commit and
+         * sync the current journal segment.
+         * There is a theoretical bug here.  Syncing the journal segment will
+         * write a number of journal entries and the final commit.  All these
+         * are written in a single operation.  If the device layer writes the
+         * data back-to-front, the commit will precede the other journal
+         * entries, leaving a race window.
+         * Two fixes are possible.  Preferred is to fix the device layer to
+         * ensure writes happen front-to-back.  Alternatively we can insert
+         * another logfs_sync_area() super->s_devops->sync() combo before
+         * writing the commit.
+         */
+        /*
+         * On another subject, super->s_devops->sync is usually not necessary.
+         * Unless called from sys_sync or friends, a barrier would suffice.
+         */
+        super->s_devops->sync(sb);
+        err = logfs_write_je(sb, logfs_write_commit);
+        if (err)
+                goto again;
+        log_journal("Write commit to %llx\n",
+                        be64_to_cpu(super->s_je_array[super->s_no_je - 1]));
+        logfs_sync_area(area);
+        BUG_ON(area->a_used_bytes != area->a_written_bytes);
+        super->s_devops->sync(sb);
+
+        mutex_unlock(&super->s_journal_mutex);
+        return;
+}
+
+void do_logfs_journal_wl_pass(struct super_block *sb)
+{
+        struct logfs_super *super = logfs_super(sb);
+        struct logfs_area *area = super->s_journal_area;
+        u32 segno, ec;
+        int i, err;
+
+        log_journal("Journal requires wear-leveling.\n");
+        /* Drop old segments */
+        journal_for_each(i)
+                if (super->s_journal_seg[i]) {
+                        logfs_set_segment_unreserved(sb,
+                                        super->s_journal_seg[i],
+                                        super->s_journal_ec[i]);
+                        super->s_journal_seg[i] = 0;
+                        super->s_journal_ec[i] = 0;
+                }
+        /* Get new segments */
+        for (i = 0; i < super->s_no_journal_segs; i++) {
+                segno = get_best_cand(sb, &super->s_reserve_list, &ec);
+                super->s_journal_seg[i] = segno;
+                super->s_journal_ec[i] = ec;
+                logfs_set_segment_reserved(sb, segno);
+        }
+        /* Manually move journal_area */
+        area->a_segno = super->s_journal_seg[0];
+        area->a_is_open = 0;
+        area->a_used_bytes = 0;
+        /* Write journal */
+        logfs_write_anchor(super->s_master_inode);
+        /* Write superblocks */
+        err = logfs_write_sb(sb);
+        BUG_ON(err);
+}
+
+static const struct logfs_area_ops journal_area_ops = {
+        .get_free_segment       = journal_get_free_segment,
+        .get_erase_count        = journal_get_erase_count,
+        .erase_segment          = journal_erase_segment,
+};
+
+int logfs_init_journal(struct super_block *sb)
+{
+        struct logfs_super *super = logfs_super(sb);
+        size_t bufsize = max_t(size_t, sb->s_blocksize, super->s_writesize)
+                + MAX_JOURNAL_HEADER;
+        int ret = -ENOMEM;
+
+        mutex_init(&super->s_journal_mutex);
+        btree_init_mempool32(&super->s_reserved_segments, super->s_btree_pool);
+
+        super->s_je = kzalloc(bufsize, GFP_KERNEL);
+        if (!super->s_je)
+                return ret;
+
+        super->s_compressed_je = kzalloc(bufsize, GFP_KERNEL);
+        if (!super->s_compressed_je)
+                return ret;
+
+        super->s_master_inode = logfs_new_meta_inode(sb, LOGFS_INO_MASTER);
+        if (IS_ERR(super->s_master_inode))
+                return PTR_ERR(super->s_master_inode);
+
+        ret = logfs_read_journal(sb);
+        if (ret)
+                return -EIO;
+
+        reserve_sb_and_journal(sb);
+        logfs_calc_free(sb);
+
+        super->s_journal_area->a_ops = &journal_area_ops;
+        return 0;
+}
+
+void logfs_cleanup_journal(struct super_block *sb)
+{
+        struct logfs_super *super = logfs_super(sb);
+
+        btree_grim_visitor32(&super->s_reserved_segments, 0, NULL);
+        destroy_meta_inode(super->s_master_inode);
+        super->s_master_inode = NULL;
+
+        kfree(super->s_compressed_je);
+        kfree(super->s_je);
+}