Hi,
I'm replying rather late but I've been busy with my PhD thesis lately.
So sorry for that.
> Move the blocks on the temporary inode to the original inode
> by a page.
> 1. Read the file data from the old blocks to the page
> 2. Move the block on the temporary inode to the original inode
> 3. Write the file data on the page into the new blocks
I have one thing - it's probably not good to use page cache for
defragmentation. As you will read/write tons of data and that will push
out all other data from the cache. I think it may be better to allocate
some separate pages and use them as buffers.
Also I'm intending to work on a similar functionality for ext3
(without extents/mballoc). It would be probably good to find some common
parts so that they don't have to be duplicated.
Honza
> Signed-off-by: Takashi Sato <sho@xxxxxxxxxxxxxx>
> ---
> diff -Nrup -X linux-2.6.19-rc6-org/Documentation/dontdiff linux-2.6.19-rc6-1/fs/ext4/extents.c linux-2.6.19-rc6-FULL/fs/ext4/extents.c
> --- linux-2.6.19-rc6-1/fs/ext4/extents.c 2007-01-16 09:46:13.000000000 +0900
> +++ linux-2.6.19-rc6-FULL/fs/ext4/extents.c 2007-01-16 09:43:45.000000000 +0900
> @@ -2539,6 +2539,470 @@ ext4_ext_next_extent(struct inode *inode
> }
>
> /**
> + * ext4_ext_merge_extents - merge new extent to the extent block
> + *
> + * @handle journal handle
> + * @inode target file's inode
> + * @org_path path indicates first extent to be defraged
> + * @o_start first original extent to be defraged
> + * @o_end last original extent to be defraged
> + * @start_ext first new extent to be merged
> + * @new_ext middle of new extent to be merged
> + * @end_ext last new extent to be merged
> + * @replaced the number of blocks which will be replaced with new_ext
> + *
> + * This function returns 0 if succeed, otherwise returns -1.
> + */
> +static int
> +ext4_ext_merge_extents(handle_t *handle, struct inode *inode,
> + struct ext4_ext_path *org_path,
> + struct ext4_extent *o_start, struct ext4_extent *o_end,
> + struct ext4_extent *start_ext, struct ext4_extent *new_ext,
> + struct ext4_extent *end_ext, unsigned long replaced)
> +{
> + int i = 0;
> + unsigned need_slots;
> + unsigned slots_range, len;
> + int range_to_move;
> + struct ext4_extent_header * eh;
> + struct ext4_extent *free_start, *free_end;
> + int depth;
> +
> + /* The extents need to be inserted
> + * start_extent + new_extent + end_extent
> + */
> + need_slots = (le16_to_cpu(start_ext->ee_len) ? 1 : 0) +
> + (le16_to_cpu(end_ext->ee_len) ? 1 : 0) +
> + (le16_to_cpu(new_ext->ee_len) ? 1 : 0);
> +
> + /* The number of slots between start and end */
> + slots_range = o_end - o_start + 1;
> +
> + /* Range to move the end of extent */
> + range_to_move = need_slots - slots_range;
> + depth = org_path->p_depth;
> + org_path += depth;
> + eh = org_path->p_hdr;
> + /* expansion */
> + if (range_to_move > 0) {
> + if (range_to_move > le16_to_cpu(eh->eh_max)
> + - le16_to_cpu(eh->eh_entries)) {
> + printk("Cannot merge extents due to no space\n");
> + return -1;
> + }
> + }
> + if (depth) {
> + /* Register to journal */
> + if (ext4_journal_get_write_access(handle, org_path->p_bh)) {
> + return -1;
> + }
> + }
> +
> + /* Free old blocks
> + * dest |---------------|
> + * org |---------------|
> + */
> + free_start = o_start;
> + free_end = o_end;
> + if (le16_to_cpu(start_ext->ee_len)) {
> + if (le16_to_cpu(o_start->ee_len)
> + > le16_to_cpu(start_ext->ee_len)) {
> + ext4_free_blocks(handle, inode,
> + ext_pblock(o_start)
> + + le16_to_cpu(start_ext->ee_len),
> + le16_to_cpu(o_start->ee_len)
> + - le16_to_cpu(start_ext->ee_len), 0);
> + }
> + free_start++;
> + }
> +
> + /* dest |----------------|
> + * org |---------------|
> + */
> + if (le16_to_cpu(end_ext->ee_len)) {
> + ext4_free_blocks(handle, inode, ext_pblock(o_end),
> + le16_to_cpu(o_end->ee_len)
> + - le16_to_cpu(end_ext->ee_len), 0);
> + free_end--;
> + }
> +
> + /* dest |-------------------|
> + * org |-----------------|
> + */
> + for (; free_start <= free_end; free_start++) {
> + ext4_free_blocks(handle, inode,
> + ext_pblock(free_start),
> + le32_to_cpu(free_start->ee_len), 0);
> + }
> +
> + /* Move the existing extents */
> + if (range_to_move && o_end < EXT_LAST_EXTENT(eh)) {
> + len = EXT_LAST_EXTENT(eh) - (o_end + 1) + 1;
> + len = len * sizeof(struct ext4_extent);
> + memmove(o_end + 1 + range_to_move, o_end + 1, len);
> + }
> +
> + /* Insert start entry */
> + if (le16_to_cpu(start_ext->ee_len)) {
> + o_start[i++].ee_len = start_ext->ee_len;
> + }
> +
> + /* Insert new entry */
> + if (le16_to_cpu(new_ext->ee_len)) {
> + o_start[i].ee_block = new_ext->ee_block;
> + o_start[i].ee_len = cpu_to_le16(replaced);
> + ext4_ext_store_pblock(&o_start[i++], ext_pblock(new_ext));
> + }
> +
> + /* Insert end entry */
> + if (end_ext->ee_len) {
> + o_start[i] = *end_ext;
> + }
> +
> + /* Increment the total entries counter on the extent block */
> + eh->eh_entries
> + = cpu_to_le16(le16_to_cpu(eh->eh_entries) + range_to_move);
> + if (depth) {
> + if (ext4_journal_dirty_metadata(handle, org_path->p_bh)) {
> + return -1;
> + }
> + } else {
> + if (ext4_mark_inode_dirty(handle, inode) < 0) {
> + return -1;
> + }
> + }
> +
> + return 0;
> +}
> +
> +/**
> + * ext4_ext_defrag_leaf_block - Defragmentation for one leaf extent block.
> + * @handle journal handle
> + * @org_inode target inode
> + * @org_path path indicates first extent to be defraged
> + * @dext destination extent
> + * @from start offset on the target file
> + *
> + * This function returns 0 if succeed, otherwise returns error value.
> + */
> +static int
> +ext4_ext_defrag_leaf_block(handle_t *handle, struct inode *org_inode,
> + struct ext4_ext_path *org_path, struct ext4_extent *dext,
> + unsigned long *from, unsigned long *delete_start)
> +{
> + unsigned long depth, replaced = 0;
> + struct ext4_extent *oext, *o_start = NULL, *o_end = NULL, *prev_ext;
> + struct ext4_extent new_ext, start_ext, end_ext;
> + unsigned long new_end;
> + unsigned long lblock;
> + unsigned long len;
> + unsigned long long new_phys_end;
> + int ret;
> +
> + depth = ext_depth(org_inode);
> + start_ext.ee_len = end_ext.ee_len = 0;
> + o_start = o_end = oext = org_path[depth].p_ext;
> + ext4_ext_store_pblock(&new_ext, ext_pblock(dext));
> + len = new_ext.ee_len = dext->ee_len;
> + new_ext.ee_block = cpu_to_le32(*from);
> + lblock = le32_to_cpu(oext->ee_block);
> + new_end = le32_to_cpu(new_ext.ee_block)
> + + le16_to_cpu(new_ext.ee_len) - 1;
> + new_phys_end = ext_pblock(&new_ext)
> + + le16_to_cpu(new_ext.ee_len) - 1;
> +
> + /* First original extent
> + * dest |---------------|
> + * org |---------------|
> + */
> + if (le32_to_cpu(new_ext.ee_block) >
> + le32_to_cpu(oext->ee_block) &&
> + le32_to_cpu(new_ext.ee_block) <
> + le32_to_cpu(oext->ee_block)
> + + le16_to_cpu(oext->ee_len)) {
> + start_ext.ee_len = cpu_to_le32(le32_to_cpu(new_ext.ee_block)
> + - le32_to_cpu(oext->ee_block));
> + replaced += le16_to_cpu(oext->ee_len)
> + - le16_to_cpu(start_ext.ee_len);
> + } else if (oext > EXT_FIRST_EXTENT(org_path[depth].p_hdr)) {
> + /* We can merge previous extent. */
> + prev_ext = oext -1;
> + if ((ext_pblock(prev_ext)
> + + le32_to_cpu(prev_ext->ee_len))
> + == ext_pblock(&new_ext)) {
> + o_start = prev_ext;
> + start_ext.ee_len = cpu_to_le32(
> + le16_to_cpu(prev_ext->ee_len)
> + + le16_to_cpu(new_ext.ee_len));
> + new_ext.ee_len = 0;
> + }
> + }
> +
> + for (;;) {
> +
> + /* The extent for destination must be found. */
> + BUG_ON(!oext || lblock != le32_to_cpu(oext->ee_block));
> + lblock += le16_to_cpu(oext->ee_len);
> +
> + /* Middle of original extent
> + * dest |-------------------|
> + * org |-----------------|
> + */
> + if (le32_to_cpu(new_ext.ee_block) <=
> + le32_to_cpu(oext->ee_block) &&
> + new_end >= le32_to_cpu(oext->ee_block)
> + + le16_to_cpu(oext->ee_len) -1) {
> + replaced += le16_to_cpu(oext->ee_len);
> + }
> +
> + /* Last original extent
> + * dest |----------------|
> + * org |---------------|
> + */
> + if (new_end >= le32_to_cpu(oext->ee_block) &&
> + new_end < le32_to_cpu(oext->ee_block)
> + + le16_to_cpu(oext->ee_len) - 1) {
> + end_ext.ee_len
> + = cpu_to_le16(le32_to_cpu(oext->ee_block)
> + + le16_to_cpu(oext->ee_len) -1 - new_end);
> + ext4_ext_store_pblock(&end_ext, (ext_pblock(o_end)
> + + cpu_to_le16(oext->ee_len)
> + - cpu_to_le16(end_ext.ee_len)));
> + end_ext.ee_block
> + = cpu_to_le32(le32_to_cpu(o_end->ee_block)
> + + le16_to_cpu(oext->ee_len)
> + - le16_to_cpu(end_ext.ee_len));
> + replaced += le16_to_cpu(oext->ee_len)
> + - le16_to_cpu(end_ext.ee_len);
> + }
> +
> + /* Detected the block end, reached the number of replaced
> + * blocks to dext->ee_len. Then, merge the extent.
> + */
> + if (oext == EXT_LAST_EXTENT(org_path[depth].p_hdr) ||
> + new_end <= le32_to_cpu(oext->ee_block)
> + + le16_to_cpu(oext->ee_len) - 1) {
> + if (ext4_ext_merge_extents(handle, org_inode,
> + org_path, o_start, o_end,
> + &start_ext, &new_ext, &end_ext, replaced) < 0) {
> + return -EIO;
> + }
> +
> + *delete_start = le32_to_cpu(new_ext.ee_block)
> + + replaced;
> +
> + /* All expected blocks are replaced */
> + if (new_ext.ee_len <= 0) {
> + if (DQUOT_ALLOC_BLOCK
> + (org_inode, len)) {
> + return -EDQUOT;
> + }
> + return 0;
> + }
> +
> + /* re-calculate new_ext */
> + new_ext.ee_len = cpu_to_le32(le16_to_cpu(new_ext.ee_len)
> + - replaced);
> + new_ext.ee_block =
> + cpu_to_le32(le32_to_cpu(new_ext.ee_block)
> + + replaced);
> + ext4_ext_store_pblock(&new_ext, ext_pblock(&new_ext)
> + + replaced);
> + replaced = 0;
> + start_ext.ee_len = end_ext.ee_len = 0;
> + o_start = NULL;
> +
> + /* All expected blocks are replaced */
> + if (new_ext.ee_len <= 0) {
> + if (DQUOT_ALLOC_BLOCK
> + (org_inode, len)) {
> + return -EDQUOT;
> + }
> + return 0;
> + }
> + }
> +
> + /* Get next extent for original. */
> + if ((ret
> + = ext4_ext_next_extent(org_inode, org_path, &oext))
> + != 0) {
> + if (ret == 1)
> + ret = -EIO;
> + return ret;
> + }
> + o_end = oext;
> + if (!o_start)
> + o_start = oext;
> + }
> +}
> +
> +/**
> + * ext4_ext_replace_branches - replace original extents with new extents.
> + * @org_inode Original inode
> + * @dest_inode temporary inode
> + * @from_page Page offset
> + * @count_page Page count to be replaced
> + * @delete_start block offset for deletion
> + *
> + * This function returns 0 if succeed, otherwise returns error value.
> + * Replace extents for blocks from "from" to "from+count-1".
> + */
> +static int
> +ext4_ext_replace_branches(struct inode *org_inode, struct inode *dest_inode,
> + pgoff_t from_page, pgoff_t dest_from_page,
> + pgoff_t count_page, unsigned long *delete_start)
> +{
> + struct ext4_ext_path *org_path = NULL;
> + struct ext4_ext_path *dest_path = NULL;
> + struct ext4_extent *oext, *dext;
> + struct ext4_extent tmp_ext;
> + int err = 0;
> + int depth;
> + unsigned long from, count, dest_off, diff, replaced_count = 0;
> + handle_t *handle = NULL;
> + unsigned jnum;
> +
> + from = from_page << (PAGE_CACHE_SHIFT - dest_inode->i_blkbits);
> + count = count_page << (PAGE_CACHE_SHIFT - dest_inode->i_blkbits);
> + dest_off = dest_from_page << (PAGE_CACHE_SHIFT -
> + dest_inode->i_blkbits);
> + jnum = ext4_ext_writepage_trans_blocks(org_inode, count) + 3;
> + handle = ext4_journal_start(org_inode, jnum);
> + if (IS_ERR(handle)) {
> + err = PTR_ERR(handle);
> + goto out;
> + }
> +
> + /* Get the original extent for the block "from" */
> + org_path = ext4_ext_find_extent(org_inode, from, NULL);
> + if (IS_ERR(org_path)) {
> + err = PTR_ERR(org_path);
> + org_path = NULL;
> + goto out;
> + }
> +
> + /* Get the destination extent for the head */
> + dest_path = ext4_ext_find_extent(dest_inode, dest_off, NULL);
> + if (IS_ERR(dest_path)) {
> + err = PTR_ERR(dest_path);
> + dest_path = NULL;
> + goto out;
> + }
> + depth = ext_depth(dest_inode);
> + dext = dest_path[depth].p_ext;
> + /* When dext is too large, pick up the target range. */
> + diff = dest_off - le32_to_cpu(dext->ee_block);
> + ext4_ext_store_pblock(&tmp_ext, ext_pblock(dext) + diff);
> + tmp_ext.ee_block = cpu_to_le32(le32_to_cpu(dext->ee_block) + diff);
> + tmp_ext.ee_len = cpu_to_le16(le16_to_cpu(dext->ee_len) - diff);
> + if (count < tmp_ext.ee_len) {
> + tmp_ext.ee_len = cpu_to_le16(count);
> + }
> + dext = &tmp_ext;
> +
> + /* loop for the destination extents */
> + while (1) {
> + /* The extent for destination must be found. */
> + BUG_ON(!dext || dest_off != le32_to_cpu(dext->ee_block));
> +
> + /* loop for the original extent blocks */
> + if ((err = ext4_ext_defrag_leaf_block(handle, org_inode,
> + org_path, dext, &from, delete_start)) < 0) {
> + goto out;
> + }
> +
> + replaced_count += le16_to_cpu(dext->ee_len);
> + dest_off += le16_to_cpu(dext->ee_len);
> + from += le16_to_cpu(dext->ee_len);
> +
> + /* Already moved the expected blocks */
> + if (replaced_count >= count)
> + break;
> +
> + /* get the next extent on both original and destination. */
> + err = ext4_ext_next_extent(dest_inode, dest_path, &dext);
> + if (err != 0) {
> + if (err > 0) {
> + err = 0;
> + }
> + goto out;
> + }
> + if ((err =
> + ext4_ext_next_extent(org_inode, org_path, &oext)) < 0) {
> + goto out;
> + }
> + }
> +out:
> + if (handle) {
> + ext4_journal_stop(handle);
> + }
> + if (org_path) {
> + ext4_ext_drop_refs(org_path);
> + kfree(org_path);
> + }
> + if (dest_path) {
> + ext4_ext_drop_refs(dest_path);
> + kfree(dest_path);
> + }
> +
> + return err;
> +}
> +
> +/**
> + * ext4_ext_remove_index_blocks - remove leaf blocks and index blocks
> + * @handle handle
> + * @dest_inode temporary inode
> + * @eh extent header
> + * @depth depth of extent tree
> + *
> + * This function returns 0 if succeed, otherwise returns error value
> + */
> +static int ext4_ext_remove_index_blocks(handle_t *handle,
> + struct inode *dest_inode,
> + struct ext4_extent_header *eh, int depth)
> +{
> + struct ext4_extent_idx *idx;
> + struct buffer_head *bh;
> + int metadata = 1;
> + int credits = 0;
> + int i, ret = 0;
> +
> + if (depth == 0) {
> + eh->eh_entries = 0;
> + return 0;
> + }
> +
> + idx = EXT_FIRST_INDEX(eh);
> +
> + for (i = 1; i <= eh->eh_entries; i++) {
> + if (depth > 1) {
> + bh = sb_bread(dest_inode->i_sb, idx->ei_leaf);
> + if (!bh) {
> + ret = -EIO;
> + } else {
> + ret = ext4_ext_remove_index_blocks(handle,
> + dest_inode, ext_block_hdr(bh),
> + depth - 1);
> + brelse(bh);
> + }
> + }
> +#ifdef CONFIG_QUOTA
> + credits = 2 * EXT4_QUOTA_TRANS_BLOCKS(dest_inode->i_sb);
> +#endif
> + handle = ext4_ext_journal_restart(handle,
> + credits + EXT4_TRANS_META_BLOCKS);
> + if (IS_ERR(handle))
> + return PTR_ERR(handle);
> +
> + ext4_free_blocks(handle, dest_inode,
> + idx->ei_leaf, 1, metadata);
> + eh->eh_entries--;
> + idx++;
> + }
> + return ret;
> +}
> +
> +/**
> * ext4_ext_alloc_blocks - allocate contiguous blocks to temporary inode
> * @dest_inode temporary inode for multiple block allocation
> * @iblock file related offset
> @@ -2673,6 +3137,61 @@ out2:
> }
>
> /**
> + * ext4_ext_defrag_partial - defrag original file partially
> + * @filp: pointer to file
> + * @org_offset: page index on original file
> + * @dest_offset: page index on temporary file
> + *
> + * This function returns 0 if succeeded, otherwise returns error value
> + */
> +static int
> +ext4_ext_defrag_partial(struct inode *tmp_inode,
> + struct file *filp,
> + pgoff_t org_offset,
> + pgoff_t dest_offset, unsigned long *delete_start)
> +{
> + struct inode *inode = filp->f_dentry->d_inode;
> + struct address_space *mapping = inode->i_mapping;
> + struct page *page;
> + pgoff_t offset_in_page = PAGE_SIZE;
> + int ret = 0;
> +
> + page = read_cache_page(inode->i_mapping,
> + org_offset, (filler_t *)inode->i_mapping->a_ops->readpage,
> + NULL);
> +
> + if (IS_ERR(page)) {
> + ret = PTR_ERR(page);
> + return ret;
> + }
> +
> + wait_on_page_locked(page);
> + lock_page(page);
> + /* release old bh and drop refs */
> + try_to_release_page(page, 0);
> + ret = ext4_ext_replace_branches(inode, tmp_inode, org_offset,
> + dest_offset, 1, delete_start);
> + if (ret < 0)
> + goto ERR;
> +
> + if (org_offset == ((inode->i_size - 1) >> PAGE_SHIFT))
> + offset_in_page = (inode->i_size & (PAGE_CACHE_SIZE - 1));
> +
> + ret = mapping->a_ops->prepare_write(filp, page,
> + 0, offset_in_page);
> + if (ret)
> + goto ERR;
> +
> + ret = mapping->a_ops->commit_write(filp, page,
> + 0, offset_in_page);
> +ERR:
> + unlock_page(page);
> + page_cache_release(page);
> +
> + return (ret < 0 ? ret : 0);
> +}
> +
> +/**
> * ext4_ext_new_extent_tree - allocate contiguous blocks
> * @inode: inode of the original file
> * @tmp_inode: inode of the temporary file
> -
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--
Jan Kara <jack@xxxxxxx>
SuSE CR Labs
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