Sorry, this patch has a fault. Block reservation should not be called if tux3_get_block_delay() return a mapped buffer. <br><br>I'll re-send it tomorrow morning.<br><br><br><div class="gmail_quote">On Thu, Jan 15, 2009 at 10:25 PM, Liu Hui <span dir="ltr"><<a href="mailto:onlyflyer@gmail.com">onlyflyer@gmail.com</a>></span> wrote:<br>
<blockquote class="gmail_quote" style="border-left: 1px solid rgb(204, 204, 204); margin: 0pt 0pt 0pt 0.8ex; padding-left: 1ex;">I think delay allocation is not only just for allocating blocks or<br>
extents at write back time but also used to merge block allocation<br>
operations which will reduce allocation times and disk fragementation.</blockquote><div> </div><div>Yep. Delay allocation reduces buffered-write latency and disk fragement as well. <br>
<br></div><blockquote class="gmail_quote" style="border-left: 1px solid rgb(204, 204, 204); margin: 0pt 0pt 0pt 0.8ex; padding-left: 1ex;"><br>
IMHO, this patch indeed delays the allocation operations but not<br>
really understand the motive of delay allocations.</blockquote><div><br><br>
Thanks. It is a very simple implementation by using the nobh routines to defer block allocation and a private page flag to reserve space.<br> <br></div><blockquote class="gmail_quote" style="border-left: 1px solid rgb(204, 204, 204); margin: 0pt 0pt 0pt 0.8ex; padding-left: 1ex;">
<br>
<br>
2009/1/15 Liu XiaoFeng <<a href="mailto:bladehliu@gmail.com">bladehliu@gmail.com</a>>:<br>
<div><div></div><div class="Wj3C7c">> Here is a simple implementation of delayed allocation for Tux3.<br>
><br>
> Delayed allocation defers block allocation from prepare-write(write-begin)<br>
> time to page writeback time. It is a powerful technique and implemented by<br>
> several filesystems such as XFS, ext4, and btrfs.<br>
><br>
> Unlike ext4's delalloc, this implementation is independent with extent tree<br>
> structure.<br>
><br>
> Signed-off by XiaoFeng Liu.<br>
><br>
> ---<br>
><br>
> balloc.c | 1<br>
> filemap.c | 108<br>
> ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++<br>
> inode.c | 2 -<br>
> super.c | 7 ++++<br>
> trace.h | 11 ++++++<br>
> tux3.h | 30 +++++++++++++++++<br>
> 6 files changed, 158 insertions(+), 1 deletion(-)<br>
><br>
><br>
> diff -pNur tux-orig/balloc.c tux-hack/balloc.c<br>
> --- tux-orig/balloc.c 2009-01-14 20:00:22.000000000 +0800<br>
> +++ tux-hack/balloc.c 2009-01-15 14:29:26.000000000 +0800<br>
> @@ -281,6 +281,7 @@ int bfree(struct sb *sb, block_t start,<br>
> clear_bits(bufdata(buffer), start, blocks);<br>
> brelse_dirty(buffer);<br>
> sb->freeblocks += blocks;<br>
> + tux3_release_blocks(sb, blocks);<br>
> //set_sb_dirty(sb);<br>
> mutex_unlock(&sb->bitmap->i_mutex);<br>
> return 0;<br>
> diff -pNur tux-orig/filemap.c tux-hack/filemap.c<br>
> --- tux-orig/filemap.c 2009-01-14 20:00:22.000000000 +0800<br>
> +++ tux-hack/filemap.c 2009-01-15 14:25:07.000000000 +0800<br>
> @@ -505,4 +505,112 @@ const struct address_space_operations tu<br>
> .sync_page = block_sync_page,<br>
> .write_begin = tux3_vol_write_begin,<br>
> };<br>
> +<br>
> +<br>
> +/*<br>
> + * Tux3's delayed allocation<br>
> + * Note: support blocksize == pagesize only<br>
> + * Written by XiaoFeng LIU <<a href="mailto:xfengliu@mail.ustc.edu.cn">xfengliu@mail.ustc.edu.cn</a>><br>
> + */<br>
> +<br>
> +/* proof of concept */<br>
> +#define NR_RESERV_BLOCKS 32<br>
> +<br>
> +static int tux3_da_reserve_blocks(struct super_block *sb, int count)<br>
> +{<br>
> + long free_blocks;<br>
> + struct sb *sbi = tux_sb(sb);<br>
> + free_blocks = percpu_counter_read_positive(freeblocks_counter(sbi));<br>
> + xtrace("freeblocks_counter %ld", free_blocks);<br>
> +<br>
> + if (free_blocks < count + NR_RESERV_BLOCKS)<br>
> + return -ENOSPC;<br>
> + percpu_counter_sub(freeblocks_counter(sbi), count);<br>
> + return 0;<br>
> +}<br>
> +<br>
> +static void tux3_da_release_blocks(struct super_block *sb, int count)<br>
> +{<br>
> + struct sb *sbi = tux_sb(sb);<br>
> + if (count) {<br>
> + percpu_counter_add(freeblocks_counter(sbi), count);<br>
> + sb->s_dirt = 1;<br>
> + }<br>
> +}<br>
> +<br>
> +static int tux3_get_block_delay(struct inode *inode, sector_t iblock,<br>
> + struct buffer_head *bh_rslt, int create)<br>
> +{<br>
> + return tux3_get_block(inode, iblock, bh_rslt, 0);<br>
> +}<br>
> +<br>
> +/*<br>
> + * a get_block() called at the writeout time.<br>
> + */<br>
> +static int tux3_get_block_write(struct inode *inode, sector_t iblock,<br>
> + struct buffer_head *bh_rslt, int create)<br>
> +{<br>
> + pgoff_t index = (pgoff_t) (iblock >> (PAGE_CACHE_SHIFT -<br>
> inode->i_blkbits));<br>
> + struct page *page = find_get_page(inode->i_mapping, index);<br>
> +<br>
> + /* the page should be here, and dirty */<br>
> + if (unlikely(!page)) {<br>
> + xtrace("find_get_page ret NULL.");<br>
> + goto out;<br>
> + }<br>
> + if (create && PageChecked(page)) {<br>
> + ClearPageChecked(page);<br>
> + tux3_da_release_blocks(inode->i_sb, 1);<br>
> + }<br>
> + if (page)<br>
> + page_cache_release(page);<br>
> +<br>
> +out:<br>
> + return tux3_get_block(inode, iblock, bh_rslt, create);<br>
> +}<br>
> +<br>
> +static int tux3_da_write_begin(struct file *file, struct address_space<br>
> *mapping,<br>
> + loff_t pos, unsigned len, unsigned flags,<br>
> + struct page **pagep, void **fsdata)<br>
> +{<br>
> + return nobh_write_begin(file, mapping, pos, len, flags, pagep, fsdata,<br>
> + tux3_get_block_delay);<br>
> +}<br>
> +<br>
> +static int tux3_da_write_end(struct file *file, struct address_space<br>
> *mapping,<br>
> + loff_t pos, unsigned len, unsigned copied,<br>
> + struct page *page, void *fsdata)<br>
> +{<br>
> + if (!PageChecked(page)) {<br>
> + int ret = tux3_da_reserve_blocks(mapping->host->i_sb, 1);<br>
> + if (ret)<br>
> + return ret;<br>
> + SetPageChecked(page);<br>
> + }<br>
> + return nobh_write_end(file, mapping, pos, len, copied, page,<br>
> fsdata);<br>
> +}<br>
> +<br>
> +static int tux3_da_writepage(struct page *page, struct writeback_control<br>
> *wbc)<br>
> +{<br>
> + return nobh_writepage(page, tux3_get_block_write, wbc);<br>
> +}<br>
> +static int tux3_da_writepages(struct address_space *mapping,<br>
> + struct writeback_control *wbc)<br>
> +{<br>
> + return mpage_writepages(mapping, wbc, tux3_get_block_write);<br>
> +}<br>
> +<br>
> +const struct address_space_operations tux_da_aops = {<br>
> + .readpage = tux3_readpage,<br>
> + .readpages = tux3_readpages,<br>
> + .writepage = tux3_da_writepage,<br>
> + .writepages = tux3_da_writepages,<br>
> + .sync_page = block_sync_page,<br>
> + .write_begin = tux3_da_write_begin,<br>
> + .write_end = tux3_da_write_end,<br>
> + .bmap = tux3_bmap,<br>
> + .direct_IO = tux3_direct_IO,<br>
> + .migratepage = buffer_migrate_page,<br>
> +};<br>
> +<br>
> #endif /* __KERNEL__ */<br>
> diff -pNur tux-orig/inode.c tux-hack/inode.c<br>
> --- tux-orig/inode.c 2009-01-14 20:00:22.000000000 +0800<br>
> +++ tux-hack/inode.c 2009-01-15 15:29:43.000000000 +0800<br>
> @@ -438,7 +438,7 @@ static void tux_setup_inode(struct inode<br>
> case S_IFREG:<br>
> inode->i_op = &tux_file_iops;<br>
> inode->i_fop = &tux_file_fops;<br>
> - inode->i_mapping->a_ops = &tux_aops;<br>
> + inode->i_mapping->a_ops = &tux_da_aops;<br>
> break;<br>
> case S_IFDIR:<br>
> inode->i_op = &tux_dir_iops;<br>
> diff -pNur tux-orig/super.c tux-hack/super.c<br>
> --- tux-orig/super.c 2009-01-14 20:00:22.000000000 +0800<br>
> +++ tux-hack/super.c 2009-01-15 14:27:53.000000000 +0800<br>
> @@ -106,6 +106,9 @@ static void tux3_put_super(struct super_<br>
> iput(sbi->volmap);<br>
> iput(sbi->logmap);<br>
><br>
> + /* destroy block allocation info */<br>
> + tux3_balloc_info_destroy(sbi);<br>
> +<br>
> sb->s_fs_info = NULL;<br>
> kfree(sbi);<br>
> }<br>
> @@ -172,6 +175,10 @@ static int tux3_fill_super(struct super_<br>
> err = tux_load_sb(sb, silent);<br>
> if (err)<br>
> goto error;<br>
> +<br>
> + /* initialize block allocation info */<br>
> + tux3_balloc_info_init(sbi);<br>
> +<br>
> printk("%s: sb %p, ops %p, depth %Lu, block %Lu, entries_per_leaf<br>
> %d\n",<br>
> __func__,<br>
> sbi-><a href="http://itable.sb" target="_blank">itable.sb</a>, sbi->itable.ops,<br>
> diff -pNur tux-orig/trace.h tux-hack/trace.h<br>
> --- tux-orig/trace.h 2009-01-14 20:00:22.000000000 +0800<br>
> +++ tux-hack/trace.h 2009-01-15 15:04:49.000000000 +0800<br>
> @@ -22,4 +22,15 @@<br>
> die(100); \<br>
> } while (0)<br>
><br>
> +<br>
> +#ifdef __KERNEL__<br>
> +/* debug macro, xiaofeng */<br>
> +#define xtrace(f, a...) { \<br>
> + printk ("(%s, %d): %s:", \<br>
> + __FILE__, __LINE__, __FUNCTION__); \<br>
> + printk (f, ## a); \<br>
> + printk ("\n"); \<br>
> + }<br>
> +<br>
> +#endif<br>
> #endif<br>
> diff -pNur tux-orig/tux3.h tux-hack/tux3.h<br>
> --- tux-orig/tux3.h 2009-01-14 20:00:22.000000000 +0800<br>
> +++ tux-hack/tux3.h 2009-01-15 15:34:37.000000000 +0800<br>
> @@ -9,6 +9,8 @@<br>
> #include <linux/fs.h><br>
> #include <linux/buffer_head.h><br>
> #include <linux/mutex.h><br>
> +#include <linux/mm.h><br>
> +#include <linux/percpu_counter.h><br>
><br>
> #if LINUX_VERSION_CODE >= KERNEL_VERSION(2,6,27)<br>
> #include <linux/cred.h> // fsuid<br>
> @@ -213,6 +215,13 @@ struct cursor {<br>
> } path[];<br>
> };<br>
><br>
> +/* Tux3 block allocation information */<br>
> +struct tux3_balloc_info {<br>
> + struct percpu_counter freeblocks_counter;<br>
> + /* nextalloc_counter, and others */<br>
> +};<br>
> +#define freeblocks_counter(sbi) (&sbi->balloc_info.freeblocks_counter)<br>
> +<br>
> /* Tux3-specific sb is a handle for the entire volume state */<br>
><br>
> struct sb {<br>
> @@ -241,6 +250,7 @@ struct sb {<br>
> struct mutex loglock; /* serialize log entries (spinlock me) */<br>
> #ifdef __KERNEL__<br>
> struct super_block *vfs_sb; /* Generic kernel superblock */<br>
> + struct tux3_balloc_info balloc_info; /* control info for block<br>
> allocation */<br>
> #else<br>
> struct dev *dev; /* userspace block device */<br>
> #endif<br>
> @@ -620,6 +630,25 @@ static inline struct inode *buffer_inode<br>
> return buffer->b_page->mapping->host;<br>
> }<br>
><br>
> +static inline void tux3_balloc_info_init(struct sb* sbi)<br>
> +{<br>
> + percpu_counter_init(freeblocks_counter(sbi), sbi->freeblocks);<br>
> +}<br>
> +static inline void tux3_balloc_info_destroy(struct sb* sbi)<br>
> +{<br>
> + percpu_counter_destroy(freeblocks_counter(sbi));<br>
> +}<br>
> +<br>
> +static inline void tux3_release_blocks(struct sb* sbi, int count)<br>
> +{<br>
> + percpu_counter_add(freeblocks_counter(sbi), count);<br>
> +}<br>
> +<br>
> +static inline void tux3_reserve_blocks(struct sb* sbi, int count)<br>
> +{<br>
> + percpu_counter_sub(freeblocks_counter(sbi), count);<br>
> +}<br>
> +<br>
> /* btree.c */<br>
> struct buffer_head *cursor_leafbuf(struct cursor *cursor);<br>
> void release_cursor(struct cursor *cursor);<br>
> @@ -678,6 +707,7 @@ int tux3_get_block(struct inode *inode,<br>
> extern const struct address_space_operations tux_aops;<br>
> extern const struct address_space_operations tux_blk_aops;<br>
> extern const struct address_space_operations tux_vol_aops;<br>
> +extern const struct address_space_operations tux_da_aops;<br>
><br>
> /* iattr.c */<br>
> unsigned encode_asize(unsigned bits);<br>
><br>
><br>
</div></div>> _______________________________________________<br>
> Tux3 mailing list<br>
> <a href="mailto:Tux3@tux3.org">Tux3@tux3.org</a><br>
> <a href="http://mailman.tux3.org/cgi-bin/mailman/listinfo/tux3" target="_blank">http://mailman.tux3.org/cgi-bin/mailman/listinfo/tux3</a><br>
><br>
><br>
--<br>
Thanks & Best Regards<br>
Liu Hui<br>
<font color="#888888">--<br>
</font></blockquote></div><br>