[Patch 08/18] fs/logfs/journal.c

Jörn Engel
2007-08-08T16:23:25Z

--- /dev/null 2007-08-05 21:14:35.622844160 +0200
+++ linux-2.6.21logfs/fs/logfs/journal.c 2007-08-08 02:57:37.000000000 +0200
@@ -0,0 +1,737 @@
+/*
+ * fs/logfs/journal.c - journal handling code
+ *
+ * As should be obvious for Linux kernel code, license is GPLv2
+ *
+ * Copyright (c) 2005-2007 Joern Engel <joern@logfs.org>
+ */
+#include "logfs.h"
+
+static void clear_retired(struct super_block *sb)
+{
+ struct logfs_super *super = logfs_super(sb);
+ int i;
+
+ for (i=0; i<JE_LAST; i++)
+ super->s_retired[i].used = 0;
+ super->s_first.used = 0;
+}
+
+static void clear_speculatives(struct super_block *sb)
+{
+ struct logfs_super *super = logfs_super(sb);
+ int i;
+
+ for (i=0; i<JE_LAST; i++)
+ super->s_speculative[i].used = 0;
+}
+
+static void retire_speculatives(struct super_block *sb)
+{
+ struct logfs_super *super = logfs_super(sb);
+ struct logfs_journal_entry *spec, *retired;
+ int i;
+
+ for (i=0; i<JE_LAST; i++) {
+ spec = super->s_speculative + i;
+ retired = super->s_retired + i;
+ if (! spec->used)
+ continue;
+ if (retired->used && (spec->version <= retired->version))
+ continue;
+ retired->used = 1;
+ retired->version = spec->version;
+ retired->offset = spec->offset;
+ retired->len = spec->len;
+ }
+ clear_speculatives(sb);
+}
+
+/*
+ * Journal entries are versioned and highest version always wins. To save
+ * some bytes, the version is only be16 instead of be64. This means versions
+ * can and regularly will wrap. However, all versions should be in a strict
+ * sequence and the total number of entries significantly lower than 2^16.
+ *
+ * So we read the first entry, store its version and substract that from
+ * any version read to normalize them. Normalized versions should all be
+ * fairly close to zero and we can again easily judge which is the highest
+ * number.
+ */
+static int scan_segment(struct super_block *sb, u32 segno)
+{
+ struct logfs_super *super = logfs_super(sb);
+ struct logfs_area *area = super->s_journal_area;
+ struct logfs_journal_header *h = super->s_compressed_je;
+ struct logfs_journal_entry *spec, *retired;
+ u64 ofs, seg_ofs = logfs_block_ofs(sb, segno, 0);
+ u32 h_ofs;
+ s16 len, type, version;
+ int err;
+
+ for (h_ofs = 0; h_ofs < super->s_segsize; h_ofs += sizeof(*h)) {
+ ofs = seg_ofs + h_ofs;
+ err = super->s_devops->read(sb, ofs, sizeof(*h), h);
+ if (err)
+ return err;
+ /* stop scanning if all 0xff */
+ if (0 && !memchr_inv(h, 0xff, sizeof(*h))) /* FIXME */
+ break;
+
+ len = be16_to_cpu(h->h_len);
+ type = be16_to_cpu(h->h_type);
+ version = be16_to_cpu(h->h_version);
+
+ if ((len < 16) || (len > sb->s_blocksize))
+ continue;
+ if ((type < JE_FIRST) || (type > JE_LAST))
+ continue;
+
+ err = super->s_devops->read(sb, ofs, len + sizeof(*h), h);
+ if (err)
+ return err;
+
+ if (h->h_crc != logfs_crc32(h, len, 4))
+ continue;
+
+ if (!super->s_first.used) {
+ super->s_first.used = 1;
+ super->s_first.version = version;
+ }
+ version -= super->s_first.version;
+
+ if (abs(version) > 1<<14)
+ return -EIO;
+
+ h_ofs += len - sizeof(*h);
+ spec = &super->s_speculative[type];
+ retired = &super->s_retired[type];
+ switch (type) {
+ default:
+ if (spec->used && (version <= spec->version))
+ break;
+ /* store speculative entry */
+ spec->used = 1;
+ spec->version = version;
+ spec->offset = ofs;
+ spec->len = len;
+ break;
+ case JE_COMMIT:
+ if (retired->used && (version <= retired->version))
+ break;
+ /* retire speculative entries */
+ retired->used = 1;
+ retired->version = version;
+ retired->offset = ofs;
+ retired->len = len;
+ retire_speculatives(sb);
+ /* and set up journal area */
+ area->a_segno = segno;
+ /*
+ * On every mount we switch to a new segment instead
+ * of writing further in the current one. While safe
+ * this method is quite wasteful and may get changed
+ * sooner or later.
+ */
+ area->a_is_open = 0;
+ break;
+ }
+ }
+ return 0;
+}
+
+static int logfs_scan_journal(struct super_block *sb)
+{
+ struct logfs_super *super = logfs_super(sb);
+ u32 segno;
+ int i, err;
+
+ clear_speculatives(sb);
+ clear_retired(sb);
+ journal_for_each(i) {
+ segno = super->s_journal_seg[i];
+ if (!segno)
+ continue;
+ err = scan_segment(sb, segno);
+ if (err)
+ return err;
+ }
+ return 0;
+}
+
+static void logfs_read_commit(struct logfs_super *super,
+ struct logfs_journal_header *h)
+{
+ super->s_last_version = be16_to_cpu(h->h_version);
+}
+
+static void logfs_calc_free(struct super_block *sb)
+{
+ struct logfs_super *super = logfs_super(sb);
+ u64 no_segs = super->s_no_segs;
+ u64 free;
+ int i;
+
+ /* superblock segment */
+ no_segs -= 1;
+ /* bad blocks */
+ no_segs -= super->s_bad_segments;
+ /* journal */
+ journal_for_each(i)
+ if (super->s_journal_seg[i])
+ no_segs--;
+
+ free = no_segs * (super->s_segsize - LOGFS_SEGMENT_RESERVE);
+ free -= super->s_used_bytes;
+ super->s_free_bytes = free;
+}
+
+static void reserve_sb_and_journal(struct super_block *sb)
+{
+ struct logfs_super *super = logfs_super(sb);
+ struct btree_head *head = &super->s_reserved_segments;
+ int i, err;
+
+ err = btree_insert(head, 0, (void*)1);
+ BUG_ON(err);
+
+ journal_for_each(i) {
+ if (! super->s_journal_seg[i])
+ continue;
+ err = btree_insert(head, super->s_journal_seg[i], (void*)1);
+ BUG_ON(err);
+ }
+}
+
+static void logfs_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);
+}
+
+static void logfs_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 = LOGFS_IF_VALID;
+ 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 logfs_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 void logfs_read_badsegments(struct super_block *sb)
+{
+ struct logfs_super *super = logfs_super(sb);
+ struct btree_head *head = &super->s_reserved_segments;
+ __be32 *seg, *bad = super->s_bb_array;
+ int err;
+
+ super->s_bad_segments = 0;
+ for (seg = bad; seg - bad < sb->s_blocksize >> 2; seg++) {
+ if (*seg == 0)
+ continue;
+ err = btree_insert(head, be32_to_cpu(*seg), (void*)1);
+ BUG_ON(err);
+ super->s_bad_segments++;
+ }
+}
+
+static void logfs_read_areas(struct super_block *sb, struct logfs_je_areas *a)
+{
+ struct logfs_area *area;
+ int i;
+
+ for (i=0; i<LOGFS_NO_AREAS; i++) {
+ area = logfs_super(sb)->s_area[i];
+ area->a_used_bytes = be32_to_cpu(a->used_bytes[i]);
+ area->a_segno = be32_to_cpu(a->segno[i]);
+ if (area->a_segno)
+ area->a_is_open = 1;
+ }
+}
+
+static void *unpack(void *from, void *to)
+{
+ struct logfs_journal_header *h = from;
+ void *data = from + sizeof(struct logfs_journal_header);
+ int err;
+ size_t inlen, outlen;
+
+ if (h->h_compr == COMPR_NONE)
+ return data;
+
+ inlen = be16_to_cpu(h->h_len) - sizeof(*h);
+ outlen = be16_to_cpu(h->h_datalen);
+ err = logfs_uncompress(data, to, inlen, outlen);
+ BUG_ON(err);
+ return to;
+}
+
+/*
+ * Journal entries come in groups of 16. The first group contains unique
+ * entries, the second group contains the write buffers for all levels.
+ * As of now, there are only two groups.
+ * The outer switch statement deals with groups (high nibble), the inner
+ * one with unique entries
+ */
+/* FIXME: make sure there are enough per-area objects in journal */
+static int logfs_read_journal(struct super_block *sb)
+{
+ struct logfs_super *super = logfs_super(sb);
+ void *block = super->s_compressed_je;
+ void *scratch = super->s_je;
+ int i, err, level;
+ struct logfs_area *area;
+
+ for (i=0; i<JE_LAST; i++) {
+ struct logfs_journal_entry *je = super->s_retired + i;
+ if (!super->s_retired[i].used) {
+ switch (i) {
+ case JE_COMMIT:
+ case JE_DYNSB:
+ case JE_ANCHOR:
+ printk(KERN_WARNING "LogFS: Missing journal "
+ "entry %x?\n", i);
+ return -EIO;
+ default:
+ continue;
+ }
+ }
+ err = super->s_devops->read(sb, je->offset, sb->s_blocksize, block);
+ if (err)
+ return err;
+
+ level = i & 0xf;
+ area = super->s_area[level];
+ switch (i & ~0xf) {
+ case JEG_BASE:
+ switch (i) {
+ case JE_COMMIT:
+ /* just reads the latest version number */
+ logfs_read_commit(super, block);
+ break;
+ case JE_DYNSB:
+ logfs_read_dynsb(sb, unpack(block, scratch));
+ break;
+ case JE_ANCHOR:
+ logfs_read_anchor(sb, unpack(block, scratch));
+ break;
+ case JE_ERASECOUNT:
+ logfs_read_erasecount(sb,unpack(block,scratch));
+ break;
+ case JE_BADSEGMENTS:
+ unpack(block, super->s_bb_array);
+ logfs_read_badsegments(sb);
+ break;
+ case JE_AREAS:
+ logfs_read_areas(sb, unpack(block, scratch));
+ break;
+ default:
+ /*
+ * Any unknown entries in this group are
+ * considered optional.
+ */
+ break;
+ }
+ break;
+ case JEG_WBUF:
+ unpack(block, area->a_wbuf);
+ break;
+ default:
+ LOGFS_BUG(sb);
+ return -EIO;
+ }
+
+ }
+ return 0;
+}
+
+/*
+ * 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];
+ ++(super->s_journal_ec[i]);
+ 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)
+{
+ return logfs_erase_segment(area->a_sb, area->a_segno);
+}
+
+static void journal_finish_area(struct logfs_area *area)
+{
+ area->a_is_open = 0;
+ area->a_used_bytes = 0;
+}
+
+static size_t __logfs_write_header(struct logfs_super *super,
+ struct logfs_journal_header *h, size_t len, size_t datalen,
+ u16 type, u8 compr)
+{
+ h->h_len = cpu_to_be16(len);
+ h->h_type = cpu_to_be16(type);
+ h->h_version = cpu_to_be16(++super->s_last_version);
+ h->h_datalen = cpu_to_be16(datalen);
+ h->h_compr = compr;
+ h->h_pad[0] = 'H';
+ h->h_pad[1] = 'A';
+ h->h_pad[2] = 'T';
+ h->h_crc = logfs_crc32(h, len, 4);
+ return len;
+}
+
+static size_t logfs_write_header(struct logfs_super *super,
+ struct logfs_journal_header *h, size_t datalen, u16 type)
+{
+ size_t len = datalen + sizeof(*h);
+
+ return __logfs_write_header(super, h, len, datalen, type, COMPR_NONE);
+}
+
+static void *logfs_write_bb(struct super_block *sb, void *h,
+ u16 *type, size_t *len)
+{
+ *type = JE_BADSEGMENTS;
+ *len = sb->s_blocksize;
+ return logfs_super(sb)->s_bb_array;
+}
+
+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 *logfs_write_wbuf(struct super_block *sb, void *h,
+ u16 *type, size_t *len)
+{
+ struct logfs_super *super = logfs_super(sb);
+ struct logfs_area *area = super->s_area[super->s_sum_index];
+
+ *type = JEG_WBUF + super->s_sum_index;
+ *len = super->s_writesize;
+ return area->a_wbuf;
+}
+
+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_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);
+ *type = JE_DYNSB;
+ *len = sizeof(*dynsb);
+ return dynsb;
+}
+
+static void *logfs_write_areas(struct super_block *sb, void *_a,
+ u16 *type, size_t *len)
+{
+ struct logfs_area *area;
+ struct logfs_je_areas *a = _a;
+ int i;
+
+ for (i=0; i<16; i++) {
+ /* FIXME: have all 16 areas */
+ a->used_bytes[i] = 0;
+ a->segno[i] = 0;
+ }
+ for (i=0; i<LOGFS_NO_AREAS; i++) {
+ area = logfs_super(sb)->s_area[i];
+ a->used_bytes[i] = cpu_to_be32(area->a_used_bytes);
+ a->segno[i] = cpu_to_be32(area->a_segno);
+ }
+ *type = JE_AREAS;
+ *len = sizeof(*a);
+ return a;
+}
+
+static void *logfs_write_commit(struct super_block *sb, void *h,
+ u16 *type, size_t *len)
+{
+ *type = JE_COMMIT;
+ *len = 0;
+ return NULL;
+}
+
+static size_t __logfs_write_je(struct super_block *sb, size_t jpos,
+ void* (*write)(struct super_block *sb, void *scratch,
+ u16 *type, size_t *len))
+{
+ struct logfs_super *super = logfs_super(sb);
+ void *scratch = super->s_je;
+ void *header = super->s_compressed_je + jpos;
+ void *data = header + sizeof(struct logfs_journal_header);
+ ssize_t max, compr_len, pad_len, full_len;
+ size_t len;
+ u16 type;
+ u8 compr = COMPR_ZLIB;
+
+ scratch = write(sb, scratch, &type, &len);
+ if (len == 0)
+ return logfs_write_header(super, header, 0, type);
+
+ max = sb->s_blocksize - jpos;
+ compr_len = logfs_compress(scratch, data, len, max);
+ if (compr_len < 0 || type == JE_ANCHOR) {
+ BUG_ON(len > max);
+ memcpy(data, scratch, len);
+ compr_len = len;
+ compr = COMPR_NONE;
+ }
+
+ pad_len = ALIGN(compr_len, 16);
+ memset(data + compr_len, 0, pad_len - compr_len);
+ full_len = pad_len + sizeof(struct logfs_journal_header);
+
+ return __logfs_write_header(super, header, full_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);
+ BUG_ON(ret);
+
+ ofs = area->a_used_bytes;
+ area->a_used_bytes += *bytes;
+
+ if (area->a_used_bytes >= logfs_super(area->a_sb)->s_segsize) {
+ logfs_close_area(area);
+ return -EAGAIN;
+ }
+ 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(struct super_block *sb,
+ void* (*write)(struct super_block *sb, void *scratch,
+ u16 *type, size_t *len))
+{
+ struct logfs_super *super = logfs_super(sb);
+ struct logfs_area *area = super->s_journal_area;
+ struct logfs_journal_header *h = super->s_compressed_je;
+ size_t len;
+ int must_pad = 0;
+ s64 ofs;
+
+ len = __logfs_write_je(sb, 0, write);
+ if (h->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);
+ return 0;
+}
+
+/*
+ * 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.
+ */
+int logfs_write_anchor(struct inode *inode)
+{
+ struct super_block *sb = inode->i_sb;
+ struct logfs_super *super = logfs_super(sb);
+ int i, err;
+
+ mutex_lock(&super->s_journal_mutex);
+
+again:
+ for (i=0; i<LOGFS_NO_AREAS; i++) {
+ super->s_sum_index = i;
+ err = logfs_write_je(sb, logfs_write_wbuf);
+ if (err)
+ goto again;
+ }
+ err = logfs_write_je(sb, logfs_write_bb);
+ 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;
+ err = logfs_write_je(sb, logfs_write_areas);
+ if (err)
+ goto again;
+ super->s_devops->sync(sb);
+ err = logfs_write_je(sb, logfs_write_commit);
+ if (err)
+ goto again;
+
+ mutex_unlock(&super->s_journal_mutex);
+ return 0;
+}
+
+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,
+ .finish_area = journal_finish_area,
+};
+
+int logfs_init_journal(struct super_block *sb)
+{
+ struct logfs_super *super = logfs_super(sb);
+ int ret = -ENOMEM;
+
+ mutex_init(&super->s_journal_mutex);
+
+ super->s_je = kzalloc(sb->s_blocksize, GFP_KERNEL);
+ if (!super->s_je)
+ goto err0;
+
+ super->s_compressed_je = kzalloc(sb->s_blocksize, GFP_KERNEL);
+ if (!super->s_compressed_je)
+ goto err1;
+
+ super->s_bb_array = kzalloc(sb->s_blocksize, GFP_KERNEL);
+ if (!super->s_bb_array)
+ goto err2;
+
+ super->s_master_inode = logfs_new_meta_inode(sb, LOGFS_INO_MASTER);
+ if (!super->s_master_inode)
+ goto err3;
+
+ /* make sure noone tries to evict this inode */
+ super->s_master_inode->i_nlink = 1;
+
+ /* logfs_scan_journal() is looking for the latest journal entries, but
+ * doesn't copy them into data structures yet. logfs_read_journal()
+ * then re-reads those entries and copies their contents over. */
+ ret = logfs_scan_journal(sb);
+ if (ret)
+ goto err3;
+ ret = logfs_read_journal(sb);
+ if (ret)
+ goto err3;
+
+ reserve_sb_and_journal(sb);
+ logfs_calc_free(sb);
+
+ super->s_journal_area->a_ops = &journal_area_ops;
+ return 0;
+err3:
+ kfree(super->s_bb_array);
+err2:
+ kfree(super->s_compressed_je);
+err1:
+ kfree(super->s_je);
+err0:
+ return ret;
+}
+
+void logfs_cleanup_journal(struct super_block *sb)
+{
+ struct logfs_super *super = logfs_super(sb);
+
+ __logfs_destroy_inode(super->s_master_inode);
+ super->s_master_inode = NULL;
+
+ kfree(super->s_bb_array);
+ kfree(super->s_compressed_je);
+ kfree(super->s_je);
+}