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Date: Sun, 10 Feb 2013 16:45:11 +0800
From: Zheng Liu <gnehzuil.liu@...il.com>
To: Theodore Ts'o <tytso@....edu>
Cc: Zheng Liu <wenqing.lz@...bao.com>, Jan kara <jack@...e.cz>,
linux-ext4@...r.kernel.org
Subject: Re: [PATCH 09/10 v5] ext4: convert unwritten extents from extent
status tree in end_io
On Fri, Feb 08, 2013 at 04:44:05PM +0800, Zheng Liu wrote:
> From: Zheng Liu <wenqing.lz@...bao.com>
>
> This commit tries to convert unwritten extents from extent status tree
> in end_io callback functions and ext4_ext_direct_IO.
>
> Signed-off-by: Zheng Liu <wenqing.lz@...bao.com>
> Cc: "Theodore Ts'o" <tytso@....edu>
> Cc: Jan kara <jack@...e.cz>
> ---
> fs/ext4/extents.c | 6 +-
> fs/ext4/extents_status.c | 180 ++++++++++++++++++++++++++++++++++++++++----
> fs/ext4/extents_status.h | 2 +
> fs/ext4/inode.c | 5 ++
> fs/ext4/page-io.c | 8 +-
> include/trace/events/ext4.h | 25 ++++++
> 6 files changed, 208 insertions(+), 18 deletions(-)
>
> diff --git a/fs/ext4/extents.c b/fs/ext4/extents.c
> index 9f21430..a03cabf 100644
> --- a/fs/ext4/extents.c
> +++ b/fs/ext4/extents.c
> @@ -4443,8 +4443,10 @@ int ext4_convert_unwritten_extents(struct inode *inode, loff_t offset,
> ret = PTR_ERR(handle);
> break;
> }
> - ret = ext4_map_blocks(handle, inode, &map,
> - EXT4_GET_BLOCKS_IO_CONVERT_EXT);
> + down_write(&EXT4_I(inode)->i_data_sem);
> + ret = ext4_ext_map_blocks(handle, inode, &map,
> + EXT4_GET_BLOCKS_IO_CONVERT_EXT);
> + up_write(&EXT4_I(inode)->i_data_sem);
> if (ret <= 0) {
> WARN_ON(ret <= 0);
> ext4_msg(inode->i_sb, KERN_ERR,
Hi Ted,
This chunk is missing in your 'dev' branch of ext4. If we call
ext4_map_blocks here, unwritten extent in disk will never be converted
because ext4_map_blocks first tries to lookup extent status tree and the
unwriten extent in this tree has been converted in end_io callback
function. It always looks up a written extent in cache, and return
immdiately. Please check it again.
Thanks,
- Zheng
> diff --git a/fs/ext4/extents_status.c b/fs/ext4/extents_status.c
> index bac5286..eab8893 100644
> --- a/fs/ext4/extents_status.c
> +++ b/fs/ext4/extents_status.c
> @@ -248,10 +248,11 @@ ext4_lblk_t ext4_es_find_delayed_extent(struct inode *inode,
> struct extent_status *es1 = NULL;
> struct rb_node *node;
> ext4_lblk_t ret = EXT_MAX_BLOCKS;
> + unsigned long flags;
>
> trace_ext4_es_find_delayed_extent_enter(inode, es->es_lblk);
>
> - read_lock(&EXT4_I(inode)->i_es_lock);
> + read_lock_irqsave(&EXT4_I(inode)->i_es_lock, flags);
> tree = &EXT4_I(inode)->i_es_tree;
>
> /* find extent in cache firstly */
> @@ -291,7 +292,7 @@ out:
> }
> }
>
> - read_unlock(&EXT4_I(inode)->i_es_lock);
> + read_unlock_irqrestore(&EXT4_I(inode)->i_es_lock, flags);
>
> ext4_es_lru_add(inode);
> trace_ext4_es_find_delayed_extent_exit(inode, es, ret);
> @@ -458,6 +459,7 @@ int ext4_es_insert_extent(struct inode *inode, ext4_lblk_t lblk,
> {
> struct extent_status newes;
> ext4_lblk_t end = lblk + len - 1;
> + unsigned long flags;
> int err = 0;
>
> es_debug("add [%u/%u) %llu %llx to extent status tree of inode %lu\n",
> @@ -471,14 +473,14 @@ int ext4_es_insert_extent(struct inode *inode, ext4_lblk_t lblk,
> ext4_es_store_status(&newes, status);
> trace_ext4_es_insert_extent(inode, &newes);
>
> - write_lock(&EXT4_I(inode)->i_es_lock);
> + write_lock_irqsave(&EXT4_I(inode)->i_es_lock, flags);
> err = __es_remove_extent(inode, lblk, end);
> if (err != 0)
> goto error;
> err = __es_insert_extent(inode, &newes);
>
> error:
> - write_unlock(&EXT4_I(inode)->i_es_lock);
> + write_unlock_irqrestore(&EXT4_I(inode)->i_es_lock, flags);
>
> ext4_es_lru_add(inode);
> ext4_es_print_tree(inode);
> @@ -498,13 +500,14 @@ int ext4_es_lookup_extent(struct inode *inode, struct extent_status *es)
> struct ext4_es_tree *tree;
> struct extent_status *es1 = NULL;
> struct rb_node *node;
> + unsigned long flags;
> int found = 0;
>
> trace_ext4_es_lookup_extent_enter(inode, es->es_lblk);
> es_debug("lookup extent in block %u\n", es->es_lblk);
>
> tree = &EXT4_I(inode)->i_es_tree;
> - read_lock(&EXT4_I(inode)->i_es_lock);
> + read_lock_irqsave(&EXT4_I(inode)->i_es_lock, flags);
>
> /* find extent in cache firstly */
> es->es_len = es->es_pblk = 0;
> @@ -539,7 +542,7 @@ out:
> es->es_pblk = es1->es_pblk;
> }
>
> - read_unlock(&EXT4_I(inode)->i_es_lock);
> + read_unlock_irqrestore(&EXT4_I(inode)->i_es_lock, flags);
>
> ext4_es_lru_add(inode);
> trace_ext4_es_lookup_extent_exit(inode, es, found);
> @@ -649,6 +652,7 @@ int ext4_es_remove_extent(struct inode *inode, ext4_lblk_t lblk,
> ext4_lblk_t len)
> {
> ext4_lblk_t end;
> + unsigned long flags;
> int err = 0;
>
> trace_ext4_es_remove_extent(inode, lblk, len);
> @@ -658,9 +662,9 @@ int ext4_es_remove_extent(struct inode *inode, ext4_lblk_t lblk,
> end = lblk + len - 1;
> BUG_ON(end < lblk);
>
> - write_lock(&EXT4_I(inode)->i_es_lock);
> + write_lock_irqsave(&EXT4_I(inode)->i_es_lock, flags);
> err = __es_remove_extent(inode, lblk, end);
> - write_unlock(&EXT4_I(inode)->i_es_lock);
> + write_unlock_irqrestore(&EXT4_I(inode)->i_es_lock, flags);
> ext4_es_print_tree(inode);
> return err;
> }
> @@ -671,6 +675,7 @@ static int ext4_es_shrink(struct shrinker *shrink, struct shrink_control *sc)
> struct ext4_sb_info, s_es_shrinker);
> struct ext4_inode_info *ei;
> struct list_head *cur, *tmp, scanned;
> + unsigned long flags;
> int nr_to_scan = sc->nr_to_scan;
> int ret, nr_shrunk = 0;
>
> @@ -687,16 +692,16 @@ static int ext4_es_shrink(struct shrinker *shrink, struct shrink_control *sc)
>
> ei = list_entry(cur, struct ext4_inode_info, i_es_lru);
>
> - read_lock(&ei->i_es_lock);
> + read_lock_irqsave(&ei->i_es_lock, flags);
> if (ei->i_es_lru_nr == 0) {
> - read_unlock(&ei->i_es_lock);
> + read_unlock_irqrestore(&ei->i_es_lock, flags);
> continue;
> }
> - read_unlock(&ei->i_es_lock);
> + read_unlock_irqrestore(&ei->i_es_lock, flags);
>
> - write_lock(&ei->i_es_lock);
> + write_lock_irqsave(&ei->i_es_lock, flags);
> ret = __es_try_to_reclaim_extents(ei, nr_to_scan);
> - write_unlock(&ei->i_es_lock);
> + write_unlock_irqrestore(&ei->i_es_lock, flags);
>
> nr_shrunk += ret;
> nr_to_scan -= ret;
> @@ -756,14 +761,15 @@ static int ext4_es_reclaim_extents_count(struct super_block *sb)
> struct ext4_sb_info *sbi = EXT4_SB(sb);
> struct ext4_inode_info *ei;
> struct list_head *cur;
> + unsigned long flags;
> int nr_cached = 0;
>
> spin_lock(&sbi->s_es_lru_lock);
> list_for_each(cur, &sbi->s_es_lru) {
> ei = list_entry(cur, struct ext4_inode_info, i_es_lru);
> - read_lock(&ei->i_es_lock);
> + read_lock_irqsave(&ei->i_es_lock, flags);
> nr_cached += ei->i_es_lru_nr;
> - read_unlock(&ei->i_es_lock);
> + read_unlock_irqrestore(&ei->i_es_lock, flags);
> }
> spin_unlock(&sbi->s_es_lru_lock);
> trace_ext4_es_reclaim_extents_count(sb, nr_cached);
> @@ -801,3 +807,147 @@ static int __es_try_to_reclaim_extents(struct ext4_inode_info *ei,
> tree->cache_es = NULL;
> return nr_shrunk;
> }
> +
> +int ext4_es_convert_unwritten_extents(struct inode *inode, loff_t offset,
> + size_t size)
> +{
> + struct ext4_es_tree *tree;
> + struct rb_node *node;
> + struct extent_status *es, orig_es, conv_es;
> + ext4_lblk_t end, len1, len2;
> + ext4_lblk_t lblk = 0, len = 0;
> + ext4_fsblk_t block;
> + unsigned long flags;
> + unsigned int blkbits;
> + int err = 0;
> +
> + trace_ext4_es_convert_unwritten_extents(inode, offset, size);
> + blkbits = inode->i_blkbits;
> + lblk = offset >> blkbits;
> + len = (EXT4_BLOCK_ALIGN(offset + size, blkbits) >> blkbits) - lblk;
> +
> + end = lblk + len - 1;
> + BUG_ON(end < lblk);
> +
> + tree = &EXT4_I(inode)->i_es_tree;
> +
> + write_lock_irqsave(&EXT4_I(inode)->i_es_lock, flags);
> + es = __es_tree_search(&tree->root, lblk);
> + if (!es)
> + goto out;
> + if (es->es_lblk > end)
> + goto out;
> +
> + tree->cache_es = NULL;
> +
> + orig_es.es_lblk = es->es_lblk;
> + orig_es.es_len = es->es_len;
> + orig_es.es_pblk = es->es_pblk;
> +
> + len1 = lblk > es->es_lblk ? lblk - es->es_lblk : 0;
> + len2 = ext4_es_end(es) > end ?
> + ext4_es_end(es) - end : 0;
> + if (len1 > 0)
> + es->es_len = len1;
> + if (len2 > 0) {
> + if (len1 > 0) {
> + struct extent_status newes;
> +
> + newes.es_lblk = end + 1;
> + newes.es_len = len2;
> + block = ext4_es_pblock(&orig_es) +
> + orig_es.es_len - len2;
> + ext4_es_store_pblock(&newes, block);
> + ext4_es_store_status(&newes, ext4_es_status(&orig_es));
> + err = __es_insert_extent(inode, &newes);
> + if (err) {
> + es->es_lblk = orig_es.es_lblk;
> + es->es_len = orig_es.es_len;
> + es->es_pblk = orig_es.es_pblk;
> + goto out;
> + }
> +
> + conv_es.es_lblk = orig_es.es_lblk + len1;
> + conv_es.es_len = orig_es.es_len - len1 - len2;
> + block = ext4_es_pblock(&orig_es) + len1;
> + ext4_es_store_pblock(&conv_es, block);
> + ext4_es_store_status(&conv_es, EXTENT_STATUS_WRITTEN);
> + err = __es_insert_extent(inode, &conv_es);
> + if (err) {
> + int err2 = __es_remove_extent(inode,
> + conv_es.es_lblk,
> + ext4_es_end(&newes));
> + if (err2)
> + goto out;
> + es->es_lblk = orig_es.es_lblk;
> + es->es_len = orig_es.es_len;
> + es->es_pblk = orig_es.es_pblk;
> + goto out;
> + }
> + } else {
> + es->es_lblk = end + 1;
> + es->es_len = len2;
> + block = ext4_es_pblock(&orig_es) +
> + orig_es.es_len - len2;
> + ext4_es_store_pblock(es, block);
> +
> + conv_es.es_lblk = orig_es.es_lblk;
> + conv_es.es_len = orig_es.es_len - len2;
> + ext4_es_store_pblock(&conv_es,
> + ext4_es_pblock(&orig_es));
> + ext4_es_store_status(&conv_es, EXTENT_STATUS_WRITTEN);
> + err = __es_insert_extent(inode, &conv_es);
> + if (err) {
> + es->es_lblk = orig_es.es_lblk;
> + es->es_len = orig_es.es_len;
> + es->es_pblk = orig_es.es_pblk;
> + }
> + }
> + goto out;
> + }
> +
> + if (len1 > 0) {
> + node = rb_next(&es->rb_node);
> + if (node)
> + es = rb_entry(node, struct extent_status, rb_node);
> + else
> + es = NULL;
> + }
> +
> + while (es && ext4_es_end(es) <= end) {
> + node = rb_next(&es->rb_node);
> + ext4_es_store_status(es, EXTENT_STATUS_WRITTEN);
> + if (!inode) {
> + es = NULL;
> + break;
> + }
> + es = rb_entry(node, struct extent_status, rb_node);
> + }
> +
> + if (es && es->es_lblk < end + 1) {
> + ext4_lblk_t orig_len = es->es_len;
> +
> + /*
> + * Here we first set conv_es just because of avoiding copy the
> + * value of es to a temporary variable.
> + */
> + len1 = ext4_es_end(es) - end;
> + conv_es.es_lblk = es->es_lblk;
> + conv_es.es_len = es->es_len - len1;
> + ext4_es_store_pblock(&conv_es, ext4_es_pblock(es));
> + ext4_es_store_status(&conv_es, EXTENT_STATUS_WRITTEN);
> +
> + es->es_lblk = end + 1;
> + es->es_len = len1;
> + block = ext4_es_pblock(es) + orig_len - len1;
> + ext4_es_store_pblock(es, block);
> +
> + err = __es_insert_extent(inode, &conv_es);
> + if (err)
> + goto out;
> + }
> +
> +out:
> + write_unlock_irqrestore(&EXT4_I(inode)->i_es_lock, flags);
> + return err;
> +}
> diff --git a/fs/ext4/extents_status.h b/fs/ext4/extents_status.h
> index 938ad2b..2849d74 100644
> --- a/fs/ext4/extents_status.h
> +++ b/fs/ext4/extents_status.h
> @@ -54,6 +54,8 @@ extern int ext4_es_remove_extent(struct inode *inode, ext4_lblk_t lblk,
> extern ext4_lblk_t ext4_es_find_delayed_extent(struct inode *inode,
> struct extent_status *es);
> extern int ext4_es_lookup_extent(struct inode *inode, struct extent_status *es);
> +extern int ext4_es_convert_unwritten_extents(struct inode *inode, loff_t offset,
> + size_t size);
>
> static inline int ext4_es_is_written(struct extent_status *es)
> {
> diff --git a/fs/ext4/inode.c b/fs/ext4/inode.c
> index 670779a..08cf720 100644
> --- a/fs/ext4/inode.c
> +++ b/fs/ext4/inode.c
> @@ -3063,6 +3063,7 @@ out:
> io_end->result = ret;
> }
>
> + ext4_es_convert_unwritten_extents(inode, offset, size);
> ext4_add_complete_io(io_end);
> }
>
> @@ -3088,6 +3089,7 @@ static void ext4_end_io_buffer_write(struct buffer_head *bh, int uptodate)
> */
> inode = io_end->inode;
> ext4_set_io_unwritten_flag(inode, io_end);
> + ext4_es_convert_unwritten_extents(inode, io_end->offset, io_end->size);
> ext4_add_complete_io(io_end);
> out:
> bh->b_private = NULL;
> @@ -3246,6 +3248,9 @@ static ssize_t ext4_ext_direct_IO(int rw, struct kiocb *iocb,
> } else if (ret > 0 && !overwrite && ext4_test_inode_state(inode,
> EXT4_STATE_DIO_UNWRITTEN)) {
> int err;
> + err = ext4_es_convert_unwritten_extents(inode, offset, ret);
> + if (err)
> + ret = err;
> /*
> * for non AIO case, since the IO is already
> * completed, we could do the conversion right here
> diff --git a/fs/ext4/page-io.c b/fs/ext4/page-io.c
> index 0016fbc..66ea30e 100644
> --- a/fs/ext4/page-io.c
> +++ b/fs/ext4/page-io.c
> @@ -276,6 +276,13 @@ static void ext4_end_bio(struct bio *bio, int error)
> error = 0;
> bio_put(bio);
>
> + /*
> + * We need to convert unwrittne extents in extent status tree before
> + * end_page_writeback() is called. Otherwise, when dioread_nolock is
> + * enabled, we will be likely to read stale data.
> + */
> + inode = io_end->inode;
> + ext4_es_convert_unwritten_extents(inode, io_end->offset, io_end->size);
> for (i = 0; i < io_end->num_io_pages; i++) {
> struct page *page = io_end->pages[i]->p_page;
> struct buffer_head *bh, *head;
> @@ -305,7 +312,6 @@ static void ext4_end_bio(struct bio *bio, int error)
> put_io_page(io_end->pages[i]);
> }
> io_end->num_io_pages = 0;
> - inode = io_end->inode;
>
> if (error) {
> io_end->flag |= EXT4_IO_END_ERROR;
> diff --git a/include/trace/events/ext4.h b/include/trace/events/ext4.h
> index f0734b3..d32e3d5 100644
> --- a/include/trace/events/ext4.h
> +++ b/include/trace/events/ext4.h
> @@ -2233,6 +2233,31 @@ TRACE_EVENT(ext4_es_lookup_extent_exit,
> __entry->found ? __entry->status : 0)
> );
>
> +TRACE_EVENT(ext4_es_convert_unwritten_extents,
> + TP_PROTO(struct inode *inode, loff_t offset, loff_t size),
> +
> + TP_ARGS(inode, offset, size),
> +
> + TP_STRUCT__entry(
> + __field( dev_t, dev )
> + __field( ino_t, ino )
> + __field( loff_t, offset )
> + __field( loff_t, size )
> + ),
> +
> + TP_fast_assign(
> + __entry->dev = inode->i_sb->s_dev;
> + __entry->ino = inode->i_ino;
> + __entry->offset = offset;
> + __entry->size = size;
> + ),
> +
> + TP_printk("dev %d,%d ino %lu convert unwritten extents [%llu/%llu",
> + MAJOR(__entry->dev), MINOR(__entry->dev),
> + (unsigned long) __entry->ino,
> + __entry->offset, __entry->size)
> +);
> +
> TRACE_EVENT(ext4_es_reclaim_extents_count,
> TP_PROTO(struct super_block *sb, int nr_cached),
>
> --
> 1.7.12.rc2.18.g61b472e
>
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