--- /dev/null 2007-03-13 19:15:28.862769062 +0100
+++ linux-2.6.21logfs/fs/logfs/readwrite.c 2007-06-03 20:06:23.000000000 +0200
@@ -0,0 +1,1084 @@
+/*
+ * fs/logfs/readwrite.c
+ *
+ * As should be obvious for Linux kernel code, license is GPLv2
+ *
+ * Copyright (c) 2005-2007 Joern Engel
+ *
+ *
+ * Actually contains five sets of very similar functions:
+ * read read blocks from a file
+ * write write blocks to a file
+ * valid check whether a block still belongs to a file
+ * truncate truncate a file
+ * rewrite move existing blocks of a file to a new location (gc helper)
+ */
+#include "logfs.h"
+
+static int logfs_read_empty(void *buf, int read_zero)
+{
+ if (!read_zero)
+ return -ENODATA;
+
+ memset(buf, 0, PAGE_CACHE_SIZE);
+ return 0;
+}
+
+static int logfs_read_embedded(struct inode *inode, void *buf)
+{
+ struct logfs_inode *li = logfs_inode(inode);
+
+ memcpy(buf, li->li_data, LOGFS_EMBEDDED_SIZE);
+ memset(buf + LOGFS_EMBEDDED_SIZE, 0,
+ PAGE_CACHE_SIZE - LOGFS_EMBEDDED_SIZE);
+ return 0;
+}
+
+static int logfs_read_direct(struct inode *inode, pgoff_t index, void *buf,
+ int read_zero)
+{
+ struct logfs_inode *li = logfs_inode(inode);
+ u64 block;
+
+ block = li->li_data[index];
+ if (!block)
+ return logfs_read_empty(buf, read_zero);
+
+ return logfs_segment_read(inode->i_sb, buf, block);
+}
+
+static __be64 *logfs_get_rblock(struct logfs_super *super)
+{
+ mutex_lock(&super->s_r_mutex);
+ return super->s_rblock;
+}
+
+static void logfs_put_rblock(struct logfs_super *super)
+{
+ mutex_unlock(&super->s_r_mutex);
+}
+
+static __be64 **logfs_get_wblocks(struct super_block *sb)
+{
+ mutex_lock(&logfs_super(sb)->s_w_mutex);
+ logfs_gc_pass(sb);
+ return logfs_super(sb)->s_wblock;
+}
+
+static __be64 **logfs_get_wblocks_nolock(struct super_block *sb)
+{
+ return logfs_super(sb)->s_wblock;
+}
+
+static void logfs_put_wblocks(struct super_block *sb)
+{
+ mutex_unlock(&logfs_super(sb)->s_w_mutex);
+}
+
+static unsigned long get_bits(u64 val, int skip, int no)
+{
+ u64 ret = val;
+
+ ret >>= skip * no;
+ ret <<= 64 - no;
+ ret >>= 64 - no;
+ return ret;
+}
+
+static int logfs_read_loop(struct inode *inode, pgoff_t index, void *buf,
+ int read_zero, int count)
+{
+ struct logfs_inode *li = logfs_inode(inode);
+ struct logfs_super *super = logfs_super(inode->i_sb);
+ __be64 *rblock;
+ u64 bofs = li->li_data[I1_INDEX + count];
+ int bits = LOGFS_BLOCK_BITS;
+ int i, ret;
+
+ if (!bofs)
+ return logfs_read_empty(buf, read_zero);
+
+ rblock = logfs_get_rblock(super);
+
+ for (i=count; i>=0; i--) {
+ ret = logfs_segment_read(inode->i_sb, rblock, bofs);
+ if (ret)
+ goto out;
+ bofs = be64_to_cpu(rblock[get_bits(index, i, bits)]);
+
+ if (!bofs) {
+ ret = logfs_read_empty(buf, read_zero);
+ goto out;
+ }
+ }
+
+ ret = logfs_segment_read(inode->i_sb, buf, bofs);
+out:
+ logfs_put_rblock(super);
+ return ret;
+}
+
+static int logfs_read_block(struct inode *inode, pgoff_t index, void *buf,
+ int read_zero)
+{
+ struct logfs_inode *li = logfs_inode(inode);
+
+ if (li->li_flags & LOGFS_IF_EMBEDDED) {
+ if (index != 0)
+ return logfs_read_empty(buf, read_zero);
+ else
+ return logfs_read_embedded(inode, buf);
+ } else if (index < I0_BLOCKS)
+ return logfs_read_direct(inode, index, buf, read_zero);
+ else if (index < I1_BLOCKS)
+ return logfs_read_loop(inode, index, buf, read_zero, 0);
+ else if (index < I2_BLOCKS)
+ return logfs_read_loop(inode, index, buf, read_zero, 1);
+ else if (index < I3_BLOCKS)
+ return logfs_read_loop(inode, index, buf, read_zero, 2);
+
+ BUG();
+ return -EIO;
+}
+
+static u64 seek_data_direct(struct inode *inode, u64 pos)
+{
+ struct logfs_inode *li = logfs_inode(inode);
+
+ for (; pos < I0_BLOCKS; pos++)
+ if (li->li_data[pos])
+ return pos;
+ return I0_BLOCKS;
+}
+
+static u64 seek_data_loop(struct inode *inode, u64 pos, int count)
+{
+ struct logfs_inode *li = logfs_inode(inode);
+ struct logfs_super *super = logfs_super(inode->i_sb);
+ __be64 *rblock;
+ u64 bofs = li->li_data[I1_INDEX + count];
+ int bits = LOGFS_BLOCK_BITS;
+ int i, ret, slot;
+
+ BUG_ON(!bofs);
+
+ rblock = logfs_get_rblock(super);
+
+ for (i=count; i>=0; i--) {
+ ret = logfs_segment_read(inode->i_sb, rblock, bofs);
+ if (ret)
+ break;
+ slot = get_bits(pos, i, bits);
+ while (slot < LOGFS_BLOCK_FACTOR && rblock[slot] == 0) {
+ slot++;
+ pos += 1 << (LOGFS_BLOCK_BITS * i);
+ }
+ if (slot >= LOGFS_BLOCK_FACTOR)
+ break;
+ bofs = be64_to_cpu(rblock[slot]);
+ }
+ logfs_put_rblock(super);
+ return pos;
+}
+
+static u64 __logfs_seek_data(struct inode *inode, u64 pos)
+{
+ struct logfs_inode *li = logfs_inode(inode);
+
+ if (li->li_flags & LOGFS_IF_EMBEDDED)
+ return pos;
+ if (pos < I0_BLOCKS) {
+ pos = seek_data_direct(inode, pos);
+ if (pos < I0_BLOCKS)
+ return pos;
+ }
+ if (pos < I1_BLOCKS) {
+ if (!li->li_data[I1_INDEX])
+ pos = I1_BLOCKS;
+ else
+ return seek_data_loop(inode, pos, 0);
+ }
+ if (pos < I2_BLOCKS) {
+ if (!li->li_data[I2_INDEX])
+ pos = I2_BLOCKS;
+ else
+ return seek_data_loop(inode, pos, 1);
+ }
+ if (pos < I3_BLOCKS) {
+ if (!li->li_data[I3_INDEX])
+ pos = I3_BLOCKS;
+ else
+ return seek_data_loop(inode, pos, 2);
+ }
+ return pos;
+}
+
+u64 logfs_seek_data(struct inode *inode, u64 pos)
+{
+ struct super_block *sb = inode->i_sb;
+ u64 ret, end;
+
+ ret = __logfs_seek_data(inode, pos);
+ end = i_size_read(inode) >> sb->s_blocksize_bits;
+ if (ret >= end)
+ ret = max(pos, end);
+ return ret;
+}
+
+static int logfs_is_valid_direct(struct logfs_inode *li, pgoff_t index, u64 ofs)
+{
+ return li->li_data[index] == ofs;
+}
+
+static int __logfs_is_valid_loop(struct inode *inode, pgoff_t index,
+ int count, u64 ofs, u64 bofs, __be64 *rblock)
+{
+ int bits = LOGFS_BLOCK_BITS;
+ int i, ret;
+
+ for (i=count; i>=0; i--) {
+ ret = logfs_segment_read(inode->i_sb, rblock, bofs);
+ if (ret)
+ return 0;
+
+ bofs = be64_to_cpu(rblock[get_bits(index, i, bits)]);
+ if (!bofs)
+ return 0;
+
+ if (bofs == ofs)
+ return 1;
+ }
+ return 0;
+}
+
+static int logfs_is_valid_loop(struct inode *inode, pgoff_t index,
+ int count, u64 ofs)
+{
+ struct logfs_inode *li = logfs_inode(inode);
+ struct logfs_super *super = logfs_super(inode->i_sb);
+ __be64 *rblock;
+ u64 bofs = li->li_data[I1_INDEX + count];
+ int ret;
+
+ if (!bofs)
+ return 0;
+
+ if (bofs == ofs)
+ return 1;
+
+ rblock = logfs_get_rblock(super);
+ ret = __logfs_is_valid_loop(inode, index, count, ofs, bofs, rblock);
+ logfs_put_rblock(super);
+ return ret;
+}
+
+static int __logfs_is_valid_block(struct inode *inode, pgoff_t index, u64 ofs)
+{
+ struct logfs_inode *li = logfs_inode(inode);
+
+ if ((inode->i_nlink == 0) && atomic_read(&inode->i_count) == 1)
+ return 0;
+
+ if (li->li_flags & LOGFS_IF_EMBEDDED)
+ return 0;
+
+ if (index < I0_BLOCKS)
+ return logfs_is_valid_direct(li, index, ofs);
+ else if (index < I1_BLOCKS)
+ return logfs_is_valid_loop(inode, index, 0, ofs);
+ else if (index < I2_BLOCKS)
+ return logfs_is_valid_loop(inode, index, 1, ofs);
+ else if (index < I3_BLOCKS)
+ return logfs_is_valid_loop(inode, index, 2, ofs);
+
+ BUG();
+ return 0;
+}
+
+int logfs_is_valid_block(struct super_block *sb, u64 ofs, u64 ino, u64 pos)
+{
+ struct inode *inode;
+ int ret, cookie;
+
+ /* Umount closes a segment with free blocks remaining. Those
+ * blocks are by definition invalid. */
+ if (ino == -1)
+ return 0;
+
+ LOGFS_BUG_ON((u64)(u_long)ino != ino, sb);
+
+ inode = logfs_iget(sb, ino, &cookie);
+ if (!inode)
+ return 0;
+
+ ret = __logfs_is_valid_block(inode, pos, ofs);
+ /*
+ * If the inode is dirty, the on-medium inode and the in-core inode
+ * differ. Any object may be valid wrt. the on-medium inode even if
+ * it is invalid wrt. the in-core inode. Deleting such an object before
+ * the in-core inode is written back can lead to data loss.
+ *
+ * Right now we unconditionally write the inode now. In the future it
+ * can make sense to have a metric whether the object in question can
+ * possibly be valid wrt. on-medium inode and only write the inode if
+ * valid objects are possible.
+ */
+ if ((ret == 0) && (inode->i_state & I_DIRTY))
+ __logfs_write_inode(inode, 0);
+
+ logfs_iput(inode, cookie);
+ return ret;
+}
+
+int logfs_readpage_nolock(struct page *page)
+{
+ struct inode *inode = page->mapping->host;
+ void *buf;
+ int ret = -EIO;
+
+ buf = kmap(page);
+ ret = logfs_read_block(inode, page->index, buf, 1);
+ kunmap(page);
+
+ if (ret) {
+ ClearPageUptodate(page);
+ SetPageError(page);
+ } else {
+ SetPageUptodate(page);
+ ClearPageError(page);
+ }
+ flush_dcache_page(page);
+
+ return ret;
+}
+
+/*
+ * logfs_file_read - generic_file_read for in-kernel buffers
+ */
+static ssize_t __logfs_inode_read(struct inode *inode, char *buf, size_t count,
+ loff_t *ppos, int read_zero)
+{
+ struct super_block *sb = inode->i_sb;
+ void *block_data = NULL;
+ loff_t size = i_size_read(inode);
+ int err = -ENOMEM;
+
+ if (*ppos >= size)
+ return 0;
+ if (count > size - *ppos)
+ count = size - *ppos;
+
+ BUG_ON(logfs_index(sb, *ppos) != logfs_index(sb, *ppos + count - 1));
+
+ block_data = kzalloc(LOGFS_BLOCKSIZE, GFP_KERNEL);
+ if (!block_data)
+ goto fail;
+
+ err = logfs_read_block(inode, logfs_index(sb, *ppos), block_data,
+ read_zero);
+ if (err)
+ goto fail;
+
+ memcpy(buf, block_data + (*ppos % LOGFS_BLOCKSIZE), count);
+ *ppos += count;
+ err = count;
+fail:
+ kfree(block_data);
+ return err;
+}
+
+static s64 logfs_segment_write_pos(struct inode *inode, void *buf, u64 pos,
+ int level, int alloc)
+{
+ return logfs_segment_write(inode, buf, logfs_index(inode->i_sb, pos),
+ level, alloc);
+}
+
+static int logfs_reserve_bytes(struct inode *inode, int bytes)
+{
+ struct logfs_super *super = logfs_super(inode->i_sb);
+
+ if (!bytes)
+ return 0;
+
+ if (super->s_free_bytes < bytes + super->s_gc_reserve)
+ return -ENOSPC;
+
+ return 0;
+}
+
+/*
+ * Not strictly a reservation, but rather a check that we still have enough
+ * space to satisfy the write.
+ */
+static int logfs_reserve_blocks(struct inode *inode, int blocks)
+{
+ return logfs_reserve_bytes(inode, blocks * LOGFS_MAX_OBJECTSIZE);
+}
+
+static int logfs_dirty_inode(struct inode *inode)
+{
+ if (inode->i_ino == LOGFS_INO_MASTER)
+ return logfs_write_anchor(inode);
+
+ mark_inode_dirty_sync(inode);
+ return 0;
+}
+
+/*
+ * File is too large for embedded data when called. Move data to first
+ * block and clear embedded area
+ */
+static int logfs_move_embedded(struct inode *inode, __be64 **wblocks)
+{
+ struct logfs_inode *li = logfs_inode(inode);
+ void *buf;
+ s64 block;
+ int i;
+
+ if (! (li->li_flags & LOGFS_IF_EMBEDDED))
+ return 0;
+
+ if (logfs_reserve_blocks(inode, 1))
+ return -ENOSPC;
+
+ buf = wblocks[0];
+
+ memcpy(buf, li->li_data, LOGFS_EMBEDDED_SIZE);
+ block = logfs_segment_write(inode, buf, 0, 0, 1);
+ if (block < 0)
+ return block;
+
+ li->li_data[0] = block;
+
+ li->li_flags &= ~LOGFS_IF_EMBEDDED;
+ for (i=1; i<LOGFS_EMBEDDED_FIELDS; i++)
+ li->li_data[i] = 0;
+
+ return logfs_dirty_inode(inode);
+}
+
+static int logfs_write_embedded(struct inode *inode, void *buf)
+{
+ struct logfs_inode *li = logfs_inode(inode);
+ void *dst = li->li_data;
+
+ memcpy(dst, buf, max((long long)LOGFS_EMBEDDED_SIZE, i_size_read(inode)));
+
+ li->li_flags |= LOGFS_IF_EMBEDDED;
+ logfs_set_blocks(inode, 0);
+
+ return logfs_dirty_inode(inode);
+}
+
+static int logfs_write_direct(struct inode *inode, pgoff_t index, void *buf)
+{
+ struct logfs_inode *li = logfs_inode(inode);
+ s64 block;
+
+ if (li->li_data[index] == 0) {
+ if (logfs_reserve_blocks(inode, 1)) {
+ return -ENOSPC;
+ }
+ }
+ block = logfs_segment_write(inode, buf, index, 0, 1);
+ if (block < 0)
+ return block;
+
+ if (li->li_data[index])
+ logfs_segment_delete(inode, li->li_data[index], index, 0);
+ li->li_data[index] = block;
+
+ return logfs_dirty_inode(inode);
+}
+
+static int logfs_write_loop(struct inode *inode, pgoff_t index, void *buf,
+ __be64 **wblocks, int count)
+{
+ struct logfs_inode *li = logfs_inode(inode);
+ u64 bofs = li->li_data[I1_INDEX + count];
+ s64 block;
+ int bits = LOGFS_BLOCK_BITS;
+ int allocs = 0;
+ int i, ret;
+
+ for (i=count; i>=0; i--) {
+ if (bofs) {
+ ret = logfs_segment_read(inode->i_sb, wblocks[i], bofs);
+ if (ret)
+ return ret;
+ } else {
+ allocs++;
+ memset(wblocks[i], 0, LOGFS_BLOCKSIZE);
+ }
+ bofs = be64_to_cpu(wblocks[i][get_bits(index, i, bits)]);
+ }
+
+ if (! wblocks[0][get_bits(index, 0, bits)])
+ allocs++;
+ if (logfs_reserve_blocks(inode, allocs))
+ return -ENOSPC;
+
+ block = logfs_segment_write(inode, buf, index, 0, allocs);
+ allocs = allocs ? allocs-1 : 0;
+ if (block < 0)
+ return block;
+
+ for (i=0; i<=count; i++) {
+ wblocks[i][get_bits(index, i, bits)] = cpu_to_be64(block);
+ block = logfs_segment_write(inode, wblocks[i], index, i+1,
+ allocs);
+ allocs = allocs ? allocs-1 : 0;
+ if (block < 0)
+ return block;
+ }
+
+ li->li_data[I1_INDEX + count] = block;
+
+ return logfs_dirty_inode(inode);
+}
+
+static int __logfs_write_buf(struct inode *inode, pgoff_t index, void *buf,
+ __be64 **wblocks)
+{
+ u64 size = i_size_read(inode);
+ int err;
+
+ inode->i_ctime.tv_sec = inode->i_mtime.tv_sec = get_seconds();
+
+ if (size <= LOGFS_EMBEDDED_SIZE)
+ return logfs_write_embedded(inode, buf);
+
+ err = logfs_move_embedded(inode, wblocks);
+ if (err)
+ return err;
+
+ if (index < I0_BLOCKS)
+ return logfs_write_direct(inode, index, buf);
+ if (index < I1_BLOCKS)
+ return logfs_write_loop(inode, index, buf, wblocks, 0);
+ if (index < I2_BLOCKS)
+ return logfs_write_loop(inode, index, buf, wblocks, 1);
+ if (index < I3_BLOCKS)
+ return logfs_write_loop(inode, index, buf, wblocks, 2);
+
+ BUG();
+ return -EIO;
+}
+
+int logfs_write_buf(struct inode *inode, pgoff_t index, void *buf)
+{
+ struct super_block *sb = inode->i_sb;
+ __be64 **wblocks;
+ int ret;
+
+ wblocks = logfs_get_wblocks(sb);
+ ret = __logfs_write_buf(inode, index, buf, wblocks);
+ logfs_put_wblocks(sb);
+ return ret;
+}
+
+static int logfs_write_buf_nolock(struct inode *inode, pgoff_t index, void *buf)
+{
+ struct super_block *sb = inode->i_sb;
+ __be64 **wblocks;
+
+ wblocks = logfs_get_wblocks_nolock(sb);
+ return __logfs_write_buf(inode, index, buf, wblocks);
+}
+
+static int logfs_delete_direct(struct inode *inode, pgoff_t index)
+{
+ struct logfs_inode *li = logfs_inode(inode);
+
+ if (li->li_data[index])
+ logfs_segment_delete(inode, li->li_data[index], index, 0);
+ li->li_data[index] = 0;
+ return logfs_dirty_inode(inode);
+}
+
+static int mem_zero(void *buf, size_t len)
+{
+ long *lmap;
+ char *cmap;
+
+ lmap = buf;
+ while (len >= sizeof(long)) {
+ if (*lmap)
+ return 0;
+ lmap++;
+ len -= sizeof(long);
+ }
+ cmap = (void*)lmap;
+ while (len) {
+ if (*cmap)
+ return 0;
+ cmap++;
+ len--;
+ }
+ return 1;
+}
+
+static int logfs_delete_loop(struct inode *inode, pgoff_t index,
+ __be64 **wblocks, int count)
+{
+ struct super_block *sb = inode->i_sb;
+ struct logfs_inode *li = logfs_inode(inode);
+ u64 bofs = li->li_data[I1_INDEX + count];
+ u64 ofs_array[LOGFS_MAX_LEVELS];
+ s64 block;
+ int bits = LOGFS_BLOCK_BITS;
+ int i, ret;
+
+ if (!bofs)
+ return 0;
+
+ for (i=count; i>=0; i--) {
+ ret = logfs_segment_read(sb, wblocks[i], bofs);
+ if (ret)
+ return ret;
+
+ bofs = be64_to_cpu(wblocks[i][get_bits(index, i, bits)]);
+ ofs_array[i+1] = bofs;
+ if (!bofs)
+ return 0;
+ }
+ logfs_segment_delete(inode, bofs, index, 0);
+ block = 0;
+
+ for (i=0; i<=count; i++) {
+ wblocks[i][get_bits(index, i, bits)] = cpu_to_be64(block);
+ if ((block == 0) && mem_zero(wblocks[i], sb->s_blocksize)) {
+ logfs_segment_delete(inode, ofs_array[i+1], index, i+1);
+ continue;
+ }
+ block = logfs_segment_write(inode, wblocks[i], index, i+1, 0);
+ if (block < 0)
+ return block;
+ }
+
+ li->li_data[I1_INDEX + count] = block;
+
+ return logfs_dirty_inode(inode);
+}
+
+static int __logfs_delete(struct inode *inode, pgoff_t index, __be64 **wblocks)
+{
+ struct logfs_inode *li = logfs_inode(inode);
+
+ inode->i_ctime.tv_sec = inode->i_mtime.tv_sec = get_seconds();
+
+ if (li->li_flags & LOGFS_IF_EMBEDDED) {
+ i_size_write(inode, 0);
+ mark_inode_dirty_sync(inode);
+ return 0;
+ }
+
+ if (index < I0_BLOCKS)
+ return logfs_delete_direct(inode, index);
+ if (index < I1_BLOCKS)
+ return logfs_delete_loop(inode, index, wblocks, 0);
+ if (index < I2_BLOCKS)
+ return logfs_delete_loop(inode, index, wblocks, 1);
+ if (index < I3_BLOCKS)
+ return logfs_delete_loop(inode, index, wblocks, 2);
+ return 0;
+}
+
+int logfs_delete(struct inode *inode, pgoff_t index)
+{
+ struct super_block *sb = inode->i_sb;
+ __be64 **wblocks;
+ int ret;
+
+ wblocks = logfs_get_wblocks(sb);
+ ret = __logfs_delete(inode, index, wblocks);
+ logfs_put_wblocks(sb);
+ return ret;
+}
+
+static int logfs_rewrite_direct(struct inode *inode, int index, pgoff_t pos,
+ void *buf, int level)
+{
+ struct logfs_inode *li = logfs_inode(inode);
+ s64 block;
+ int err;
+
+ block = li->li_data[index];
+ BUG_ON(block == 0);
+
+ err = logfs_segment_read(inode->i_sb, buf, block);
+ if (err)
+ return err;
+
+ block = logfs_segment_write(inode, buf, pos, level, 0);
+ if (block < 0)
+ return block;
+
+ li->li_data[index] = block;
+
+ return logfs_dirty_inode(inode);
+}
+
+static int logfs_rewrite_loop(struct inode *inode, pgoff_t index, void *buf,
+ __be64 **wblocks, int count, int level)
+{
+ struct logfs_inode *li = logfs_inode(inode);
+ u64 bofs = li->li_data[I1_INDEX + count];
+ s64 block;
+ int bits = LOGFS_BLOCK_BITS;
+ int i, err;
+
+ if (level > count)
+ return logfs_rewrite_direct(inode, I1_INDEX + count, index, buf,
+ level);
+
+ for (i=count; i>=level; i--) {
+ if (bofs) {
+ err = logfs_segment_read(inode->i_sb, wblocks[i], bofs);
+ if (err)
+ return err;
+ } else {
+ BUG();
+ }
+ bofs = be64_to_cpu(wblocks[i][get_bits(index, i, bits)]);
+ }
+
+ block = be64_to_cpu(wblocks[level][get_bits(index, level, bits)]);
+ LOGFS_BUG_ON(!block, inode->i_sb);
+
+ err = logfs_segment_read(inode->i_sb, buf, block);
+ if (err)
+ return err;
+
+ block = logfs_segment_write(inode, buf, index, level, 0);
+ if (block < 0)
+ return block;
+
+ for (i=level; i<=count; i++) {
+ wblocks[i][get_bits(index, i, bits)] = cpu_to_be64(block);
+ block = logfs_segment_write(inode, wblocks[i], index, i+1, 0);
+ if (block < 0)
+ return block;
+ }
+
+ li->li_data[I1_INDEX + count] = block;
+
+ return logfs_dirty_inode(inode);
+}
+
+static int __logfs_rewrite_block(struct inode *inode, pgoff_t index, void *buf,
+ __be64 **wblocks, int level)
+{
+ if (level >= LOGFS_MAX_LEVELS)
+ level -= LOGFS_MAX_LEVELS;
+ BUG_ON(level >= LOGFS_MAX_LEVELS);
+
+ if (index < I0_BLOCKS)
+ return logfs_rewrite_direct(inode, index, index, buf, level);
+ if (index < I1_BLOCKS)
+ return logfs_rewrite_loop(inode, index, buf, wblocks, 0, level);
+ if (index < I2_BLOCKS)
+ return logfs_rewrite_loop(inode, index, buf, wblocks, 1, level);
+ if (index < I3_BLOCKS)
+ return logfs_rewrite_loop(inode, index, buf, wblocks, 2, level);
+
+ BUG();
+ return -EIO;
+}
+
+int logfs_rewrite_block(struct inode *inode, pgoff_t index, u64 ofs, int level)
+{
+ struct logfs_super *super = logfs_super(inode->i_sb);
+ __be64 **wblocks;
+ void *buf;
+ int ret;
+
+ wblocks = super->s_wblock;
+ buf = wblocks[LOGFS_MAX_INDIRECT];
+ ret = __logfs_rewrite_block(inode, index, buf, wblocks, level);
+ return ret;
+}
+
+/*
+ * Three cases exist:
+ * size <= pos - remove full block
+ * size >= pos + chunk - do nothing
+ * pos < size < pos + chunk - truncate, rewrite
+ */
+static s64 __logfs_truncate_i0(struct inode *inode, u64 size, u64 bofs,
+ u64 pos, __be64 **wblocks)
+{
+ size_t len = size - pos;
+ void *buf = wblocks[LOGFS_MAX_INDIRECT];
+ int err;
+
+ if (size <= pos) {
+ /* remove whole block */
+ logfs_segment_delete(inode, bofs,
+ pos >> inode->i_sb->s_blocksize_bits, 0);
+ return 0;
+ }
+
+ /* truncate this block, rewrite it */
+ err = logfs_segment_read(inode->i_sb, buf, bofs);
+ if (err)
+ return err;
+
+ memset(buf + len, 0, LOGFS_BLOCKSIZE - len);
+ return logfs_segment_write_pos(inode, buf, pos, 0, 0);
+}
+
+/* FIXME: these need to become per-sb once we support different blocksizes */
+static u64 logfs_factor[] = {
+ LOGFS_BLOCKSIZE,
+ LOGFS_I1_SIZE,
+ LOGFS_I2_SIZE,
+ LOGFS_I3_SIZE
+};
+
+static u64 logfs_start[] = {
+ LOGFS_I0_SIZE,
+ LOGFS_I1_SIZE,
+ LOGFS_I2_SIZE,
+ LOGFS_I3_SIZE
+};
+
+/*
+ * One recursion per indirect block. Logfs supports 5fold indirect blocks.
+ */
+static s64 __logfs_truncate_loop(struct inode *inode, u64 size, u64 old_bofs,
+ u64 pos, __be64 **wblocks, int i)
+{
+ struct super_block *sb = inode->i_sb;
+ struct logfs_super *super = logfs_super(sb);
+ s64 ofs;
+ int e, ret;
+
+ ret = logfs_segment_read(sb, wblocks[i], old_bofs);
+ if (ret)
+ return ret;
+
+ for (e = LOGFS_BLOCK_FACTOR-1; e>=0; e--) {
+ u64 bofs;
+ u64 new_pos = pos + e*logfs_factor[i];
+
+ if (size >= new_pos + logfs_factor[i])
+ break;
+
+ bofs = be64_to_cpu(wblocks[i][e]);
+ if (!bofs)
+ continue;
+
+ LOGFS_BUG_ON(bofs > super->s_size, sb);
+
+ if (i)
+ ofs = __logfs_truncate_loop(inode, size, bofs, new_pos,
+ wblocks, i-1);
+ else
+ ofs = __logfs_truncate_i0(inode, size, bofs, new_pos,
+ wblocks);
+ if (ofs < 0)
+ return ofs;
+
+ wblocks[i][e] = cpu_to_be64(ofs);
+ }
+
+ if (size <= max(pos, logfs_start[i])) {
+ /* complete indirect block is removed */
+ logfs_segment_delete(inode, old_bofs, logfs_index(sb,pos), i+1);
+ return 0;
+ }
+
+ /* partially removed - write back */
+ return logfs_segment_write_pos(inode, wblocks[i], pos, i, 0);
+}
+
+static int logfs_truncate_direct(struct inode *inode, u64 size,
+ __be64 **wblocks)
+{
+ struct logfs_inode *li = logfs_inode(inode);
+ int e;
+ s64 bofs, ofs;
+
+ for (e = I1_INDEX-1; e>=0; e--) {
+ u64 new_pos = e*logfs_factor[0];
+
+ if (size > e*logfs_factor[0])
+ break;
+
+ bofs = li->li_data[e];
+ if (!bofs)
+ continue;
+
+ ofs = __logfs_truncate_i0(inode, size, bofs, new_pos, wblocks);
+ if (ofs < 0)
+ return ofs;
+
+ li->li_data[e] = ofs;
+ }
+ return 0;
+}
+
+static int logfs_truncate_loop(struct inode *inode, u64 size, __be64 **wblocks,
+ int i)
+{
+ struct logfs_inode *li = logfs_inode(inode);
+ u64 bofs = li->li_data[I1_INDEX + i];
+ s64 ofs;
+
+ if (!bofs)
+ return 0;
+
+ ofs = __logfs_truncate_loop(inode, size, bofs, 0, wblocks, i);
+ if (ofs < 0)
+ return ofs;
+
+ li->li_data[I1_INDEX + i] = ofs;
+ return 0;
+}
+
+static void logfs_truncate_embedded(struct inode *inode, u64 size)
+{
+ struct logfs_inode *li = logfs_inode(inode);
+ void *buf = (void*)li->li_data + size;
+ size_t len = LOGFS_EMBEDDED_SIZE - size;
+
+ if (size >= LOGFS_EMBEDDED_SIZE)
+ return;
+ memset(buf, 0, len);
+}
+
+static void __logfs_truncate(struct inode *inode, __be64 **wblocks)
+{
+ struct logfs_inode *li = logfs_inode(inode);
+ u64 size = i_size_read(inode);
+ int ret;
+
+ if (li->li_flags & LOGFS_IF_EMBEDDED)
+ return logfs_truncate_embedded(inode, size);
+
+ if (size >= logfs_factor[3])
+ return;
+ ret = logfs_truncate_loop(inode, size, wblocks, 2);
+ BUG_ON(ret);
+
+ if (size >= logfs_factor[2])
+ return;
+ ret = logfs_truncate_loop(inode, size, wblocks, 1);
+ BUG_ON(ret);
+
+ if (size >= logfs_factor[1])
+ return;
+ ret = logfs_truncate_loop(inode, size, wblocks, 0);
+ BUG_ON(ret);
+
+ ret = logfs_truncate_direct(inode, size, wblocks);
+ BUG_ON(ret);
+
+ if (size == 0)
+ li->li_flags |= LOGFS_IF_EMBEDDED;
+}
+
+void logfs_truncate(struct inode *inode)
+{
+ struct super_block *sb = inode->i_sb;
+ __be64 **wblocks;
+
+ wblocks = logfs_get_wblocks(sb);
+ __logfs_truncate(inode, wblocks);
+ logfs_put_wblocks(sb);
+ mark_inode_dirty_sync(inode);
+}
+
+static ssize_t __logfs_inode_write(struct inode *inode, const char *buf,
+ size_t count, loff_t *ppos, int lock)
+{
+ struct super_block *sb = inode->i_sb;
+ void *block_data = NULL;
+ pgoff_t index = logfs_index(sb, *ppos);
+ int err = -ENOMEM;
+
+ BUG_ON(index != logfs_index(sb, *ppos + count - 1));
+
+ block_data = kzalloc(LOGFS_BLOCKSIZE, GFP_KERNEL);
+ if (!block_data)
+ goto fail;
+
+ err = logfs_read_block(inode, index, block_data, 1);
+ if (err)
+ goto fail;
+
+ memcpy(block_data + (*ppos % LOGFS_BLOCKSIZE), buf, count);
+
+ if (i_size_read(inode) < *ppos + count)
+ i_size_write(inode, *ppos + count);
+
+ if (lock)
+ err = logfs_write_buf(inode, index, block_data);
+ else
+ err = logfs_write_buf_nolock(inode, index, block_data);
+ if (err)
+ goto fail;
+
+ *ppos += count;
+ err = count;
+fail:
+ kfree(block_data);
+ return err;
+}
+
+int logfs_inode_read(struct inode *inode, void *buf, size_t n, loff_t _pos)
+{
+ loff_t pos = _pos << inode->i_sb->s_blocksize_bits;
+ ssize_t ret;
+
+ if (pos >= i_size_read(inode))
+ return -EOF;
+ ret = __logfs_inode_read(inode, buf, n, &pos, 0);
+ if (ret < 0)
+ return ret;
+ ret = ret==n ? 0 : -EIO;
+ return ret;
+}
+
+int logfs_inode_write(struct inode *inode, const void *buf, size_t n,
+ loff_t _pos, int lock)
+{
+ loff_t pos = _pos << inode->i_sb->s_blocksize_bits;
+ ssize_t ret;
+
+ ret = __logfs_inode_write(inode, buf, n, &pos, lock);
+ if (ret < 0)
+ return ret;
+ return ret==n ? 0 : -EIO;
+}
+
+int logfs_init_rw(struct logfs_super *super)
+{
+ int i;
+
+ mutex_init(&super->s_r_mutex);
+ mutex_init(&super->s_w_mutex);
+ super->s_rblock = kmalloc(LOGFS_BLOCKSIZE, GFP_KERNEL);
+ if (!super->s_wblock)
+ return -ENOMEM;
+ for (i=0; i<=LOGFS_MAX_INDIRECT; i++) {
+ super->s_wblock[i] = kmalloc(LOGFS_BLOCKSIZE, GFP_KERNEL);
+ if (!super->s_wblock) {
+ logfs_cleanup_rw(super);
+ return -ENOMEM;
+ }
+ }
+
+ return 0;
+}
+
+void logfs_cleanup_rw(struct logfs_super *super)
+{
+ int i;
+
+ for (i=0; i<=LOGFS_MAX_INDIRECT; i++)
+ kfree(super->s_wblock[i]);
+ kfree(super->s_rblock);
+}
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