[Patch 14/18] fs/logfs/segment.c
Jörn Engel
joern at lazybastard.org
Sun Jun 3 16:14:59 EDT 2007
--- /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);
+}
More information about the linux-mtd
mailing list