[PATCH] squahsfs: read synchronously when readahead window is small

[Minchan Kim]

Normally, MM does readahead with small window size so in that case,
our plugging logic can hurt performance.
If readahead window is smaller than compress block size, let's do
old synchronous read.

Signed-off-by: Minchan Kim <minchan@xxxxxxxxxx>
---
 fs/squashfs/file.c |   18 ++++++++++++++++++
 1 file changed, 18 insertions(+)

diff --git a/fs/squashfs/file.c b/fs/squashfs/file.c
index b98965c..2537eeb 100644
--- a/fs/squashfs/file.c
+++ b/fs/squashfs/file.c
@@ -1007,6 +1007,24 @@ static int squashfs_readpages(struct file *file, struct address_space *mapping,
 	start_bindex = hpage->index >> (msblk->block_log - PAGE_CACHE_SHIFT);
 	last_bindex = tpage->index >> (msblk->block_log - PAGE_CACHE_SHIFT);
 
+	/*
+	 * Normally, MM readahread window is smaller than our compressed
+	 * block size. In that case, plugging could hurt performance so
+	 * let's do synchronous read in that case.
+	 */
+	if (start_bindex == last_bindex) {
+		list_del(&hpage->lru);
+		if (add_to_page_cache_lru(hpage, mapping, hpage->index,
+				GFP_KERNEL)) {
+			page_cache_release(hpage);
+			return 0;
+		}
+
+		ret = squashfs_readpage(file, hpage);
+		page_cache_release(hpage);
+		return ret;
+	}
+
 	if (last_bindex >= (i_size_read(inode) >> msblk->block_log))
 		return 0;
 
-- 
1.7.9.5


On Tue, Sep 17, 2013 at 10:52:14AM +0900, Minchan Kim wrote:
> This patch had a bug so I send fixed below patchset.
> Thanks.
> 
> >From ccbf1322b6322bc34bb3e6f75a27f4fecf84ed02 Mon Sep 17 00:00:00 2001
> From: Minchan Kim <minchan@xxxxxxxxxx>
> Date: Mon, 16 Sep 2013 14:28:49 +0900
> Subject: [RFC 5/5] squashfs: support readpages
> 
> This patch supports squashfs_readpages so it can do readahead pages
> without unplugging I/O scheduler. With blktrace, I confirmed following test.
> 
> 2 compression ratio 1G file(ie, 500M consumed by real storage) sequential read
> with fadvise(SEQUENTIAL) hint and tune some knobs for block device and read_ahead_kb.
> 
> Old :
>  Reads Queued:      524289,   524289KiB  Writes Queued:           0,        0KiB
>  Read Dispatches:     4096,   524289KiB  Write Dispatches:        0,        0KiB
>  Reads Requeued:         0               Writes Requeued:         0
>  Reads Completed:     4096,   524289KiB  Writes Completed:        0,        0KiB
>  Read Merges:       520193,   520193KiB  Write Merges:            0,        0KiB
>  PC Reads Queued:        0,        0KiB  PC Writes Queued:        0,        0KiB
>  PC Read Disp.:         10,        0KiB  PC Write Disp.:          0,        0KiB
>  PC Reads Req.:          0               PC Writes Req.:          0
>  PC Reads Compl.:        0               PC Writes Compl.:        0
>  IO unplugs:          4096               Timer unplugs:           0
> 
> New :
>  Reads Queued:      524289,   524289KiB  Writes Queued:           0,        0KiB
>  Read Dispatches:      633,   524289KiB  Write Dispatches:        0,        0KiB
>  Reads Requeued:         0               Writes Requeued:         0
>  Reads Completed:      633,   524289KiB  Writes Completed:        0,        0KiB
>  Read Merges:       523656,   523656KiB  Write Merges:            0,        0KiB
>  PC Reads Queued:        0,        0KiB  PC Writes Queued:        0,        0KiB
>  PC Read Disp.:          7,        0KiB  PC Write Disp.:          0,        0KiB
>  PC Reads Req.:          0               PC Writes Req.:          0
>  PC Reads Compl.:        0               PC Writes Compl.:        0
>  IO unplugs:            31               Timer unplugs:           0
> 
> IOW, lots of I/O were merged before issuing. Of course, I can confirm that with
> blktrace.
> 
> old:
> 
>   8,34   0     1933     0.014381550  4957  Q   R 4197628 + 2 [seqread]
>   8,34   0     1934     0.014381629  4957  M   R 4197628 + 2 [seqread]
>   8,32   0     1935     0.014381821  4957  A   R 4197630 + 2 <- (8,34) 1278
>   8,34   0     1936     0.014381919  4957  Q   R 4197630 + 2 [seqread]
>   8,34   0     1937     0.014381998  4957  M   R 4197630 + 2 [seqread]
>   8,32   0     1938     0.014382131  4957  A   R 4197632 + 2 <- (8,34) 1280
>   8,34   0     1939     0.014382203  4957  Q   R 4197632 + 2 [seqread]
>   8,34   0     1940     0.014382281  4957  M   R 4197632 + 2 [seqread]
>   8,34   0     1941     0.014382873  4957  I   R 4197378 + 256 [seqread]
>   8,34   0        0     0.014383649     0  m   N cfq4957S  / insert_request
>   8,34   0        0     0.014384609     0  m   N cfq4957S  / dispatch_insert
>   8,34   0        0     0.014385132     0  m   N cfq4957S  / dispatched a request
>   8,34   0        0     0.014385460     0  m   N cfq4957S  / activate rq, drv=1
>   8,34   0     1942     0.014385581  4957  D   R 4197378 + 256 [seqread]
> 
> new:
> 
>   8,34   0    98321     0.352583517  5101  M   R 4261888 + 2 [seqread]
>   8,34   0    98322     0.353008833  5101  I   R 4230404 + 4096 [seqread]
>   8,34   0        0     0.353012357     0  m   N cfq5101SN / insert_request
>   8,34   0    98323     0.353013872  5101  I   R 4234500 + 4096 [seqread]
>   8,34   0        0     0.353014218     0  m   N cfq5101SN / insert_request
>   8,34   0    98324     0.353014553  5101  I   R 4238596 + 4096 [seqread]
>   8,34   0        0     0.353014802     0  m   N cfq5101SN / insert_request
>   8,34   0    98325     0.353014992  5101  I   R 4242692 + 4096 [seqread]
>   8,34   0        0     0.353015315     0  m   N cfq5101SN / insert_request
> 
> Voila, it's a result by that.
> elapsed time, old : 17.5 sec new : 11.5 sec
> 
> A drawback from my mind is magic value 3ms for waiting more I/O so that
> it can make delay at least 3ms although the I/O was done earlier.
> The reason I selected that value is that it was a vaule kblockd had used
> for a long time to plug/unplug for scheduler until we introduced explicit
> blk_[start|finish]_plug. If it's really problem, we can add a hook into
> plug and flush the I/O if someone is waiting the I/O.
> 
> Signed-off-by: Minchan Kim <minchan@xxxxxxxxxx>
> ---
>  fs/squashfs/block.c          |   2 -
>  fs/squashfs/file.c           | 447 ++++++++++++++++++++++++++++++++++++++++++-
>  fs/squashfs/squashfs.h       |   3 +
>  fs/squashfs/squashfs_fs_sb.h |   4 +
>  fs/squashfs/super.c          |   4 +-
>  5 files changed, 450 insertions(+), 10 deletions(-)
> 
> diff --git a/fs/squashfs/block.c b/fs/squashfs/block.c
> index d41bac8..e8bf200 100644
> --- a/fs/squashfs/block.c
> +++ b/fs/squashfs/block.c
> @@ -76,8 +76,6 @@ static struct buffer_head *get_block_length(struct super_block *sb,
>  	return bh;
>  }
>  
> -
> -
>  int squashfs_decompress_block(struct super_block *sb, int compressed,
>  		void **buffer, struct buffer_head **bh, int nr_bh,
>  		int offset, int length, int srclength, int pages)
> diff --git a/fs/squashfs/file.c b/fs/squashfs/file.c
> index 36508c3..b98965c 100644
> --- a/fs/squashfs/file.c
> +++ b/fs/squashfs/file.c
> @@ -47,6 +47,7 @@
>  #include <linux/string.h>
>  #include <linux/pagemap.h>
>  #include <linux/mutex.h>
> +#include <linux/swap.h>
>  
>  #include "squashfs_fs.h"
>  #include "squashfs_fs_sb.h"
> @@ -454,8 +455,55 @@ error_out:
>  	return 0;
>  }
>  
> -static int squashfs_hole_readpage(struct file *file, struct inode *inode,
> -				int index, struct page *page)
> +static int squashfs_hole_readpages(struct inode *inode, int index,
> +				struct list_head *page_list)
> +{
> +	struct squashfs_sb_info *msblk = inode->i_sb->s_fs_info;
> +	int bytes, i, offset = 0;
> +	void *pageaddr;
> +	struct page *push_page;
> +
> +	int start_index = index << (msblk->block_log - PAGE_CACHE_SHIFT);
> +	int file_end = i_size_read(inode) >> msblk->block_log;
> +
> +	bytes = index == file_end ?
> +		(i_size_read(inode) & (msblk->block_size - 1)) :
> +		 msblk->block_size;
> +
> +	/*
> +	 * Loop copying datablock into pages.  As the datablock likely covers
> +	 * many PAGE_CACHE_SIZE pages (default block size is 128 KiB) explicitly
> +	 * grab the pages from the page cache, except for the page that we've
> +	 * been called to fill.
> +	 */
> +	for (i = start_index; bytes > 0; i++,
> +			bytes -= PAGE_CACHE_SIZE, offset += PAGE_CACHE_SIZE) {
> +
> +		push_page = list_entry(page_list->prev, struct page, lru);
> +		list_del(&push_page->lru);
> +
> +		pageaddr = kmap_atomic(push_page);
> +		memset(pageaddr, 0, PAGE_CACHE_SIZE);
> +		kunmap_atomic(pageaddr);
> +		flush_dcache_page(push_page);
> +		SetPageUptodate(push_page);
> +
> +		lru_cache_add_file(push_page);
> +		unlock_page(push_page);
> +		page_cache_release(push_page);
> +	}
> +
> +	while (!list_empty(page_list)) {
> +		push_page = list_entry(page_list->prev, struct page, lru);
> +		list_del(&push_page->lru);
> +		page_cache_release(push_page);
> +	}
> +
> +	return 0;
> +}
> +
> +static int squashfs_hole_readpage(struct inode *inode, int index,
> +				struct page *page)
>  {
>  	struct squashfs_sb_info *msblk = inode->i_sb->s_fs_info;
>  	int bytes, i, offset = 0;
> @@ -478,8 +526,8 @@ static int squashfs_hole_readpage(struct file *file, struct inode *inode,
>  			bytes -= PAGE_CACHE_SIZE, offset += PAGE_CACHE_SIZE) {
>  		struct page *push_page;
>  
> -		push_page = (page && i == page->index) ? page :
> -			grab_cache_page_nowait(page->mapping, i);
> +		push_page = (i == page->index) ? page :
> +			grab_cache_page_nowait(inode->i_mapping, i);
>  
>  		if (!push_page)
>  			continue;
> @@ -494,7 +542,7 @@ static int squashfs_hole_readpage(struct file *file, struct inode *inode,
>  		SetPageUptodate(push_page);
>  skip_page:
>  		unlock_page(push_page);
> -		if (page && i == page->index)
> +		if (i == page->index)
>  			continue;
>  		page_cache_release(push_page);
>  	}
> @@ -533,7 +581,7 @@ static int squashfs_regular_readpage(struct file *file, struct page *page)
>  		goto error_out;
>  
>  	if (bsize == 0)
> -		return squashfs_hole_readpage(file, inode, index, page);
> +		return squashfs_hole_readpage(inode, index, page);
>  
>  	/*
>  	 * Read and decompress data block
> @@ -660,6 +708,391 @@ out:
>  	return 0;
>  }
>  
> +static int squashfs_ra_readblock(struct inode *inode, int index,
> +			struct buffer_head **bh, int *nr_bh,
> +			int *block_size, u64 *block)
> +{
> +	int bsize;
> +	struct squashfs_sb_info *msblk = inode->i_sb->s_fs_info;
> +	int ret, b;
> +
> +	/*
> +	 * Reading a datablock from disk.  Need to read block list
> +	 * to get location and block size.
> +	 */
> +	*block_size = read_blocklist(inode, index, block);
> +	if (*block_size < 0)
> +		return 1;
> +
> +	if (*block_size == 0)
> +		return 0;
> +
> +	bsize = SQUASHFS_COMPRESSED_SIZE_BLOCK(*block_size);
> +	ret = squashfs_read_submit(inode->i_sb, *block, bsize,
> +				msblk->block_size, bh, &b);
> +	if (ret < 0)
> +		return ret;
> +
> +	*nr_bh = b;
> +	return 0;
> +}
> +
> +struct squashfs_ra_private {
> +	struct buffer_head **bh;
> +	int nr_bh;
> +	int block_size;
> +	u64 block;
> +	void **buffer;
> +	struct page **page_array;
> +};
> +
> +/* Caller should free buffer head */
> +static int squashfs_ra_read_submit(struct inode *inode, int bindex,
> +			struct squashfs_ra_private *ra_priv)
> +{
> +	struct squashfs_sb_info *msblk = inode->i_sb->s_fs_info;
> +	int ret;
> +	struct buffer_head **bh;
> +	int nr_bh = -1, bsize;
> +	u64 block;
> +	bh = kcalloc(((msblk->block_size + msblk->devblksize - 1)
> +				>> msblk->devblksize_log2) + 1,
> +				sizeof(*bh), GFP_KERNEL);
> +	if (!bh)
> +		return -ENOMEM;
> +
> +	ra_priv->bh = bh;
> +	ret = squashfs_ra_readblock(inode, bindex, bh, &nr_bh,
> +					&bsize, &block);
> +	if (ret != 0)
> +		goto release_bh;
> +
> +	ra_priv->nr_bh = nr_bh;
> +	ra_priv->block_size = bsize;
> +	ra_priv->block = block;
> +
> +	return 0;
> +
> +release_bh:
> +	kfree(ra_priv->bh);
> +	return ret;
> +}
> +
> +static int squashfs_ra_decompress(struct inode *inode, int bindex,
> +			struct squashfs_ra_private *ra_priv, gfp_t gfp_mask,
> +			struct list_head *page_list)
> +{
> +	int j;
> +	int ret = -ENOMEM;
> +	struct squashfs_sb_info *msblk = inode->i_sb->s_fs_info;
> +	int pages_per_block;
> +
> +	void **buffer;
> +	struct buffer_head **bh;
> +	int block_size, nr_bh;
> +	u64 block;
> +	struct page **page_array, *page;
> +
> +	int compressed, offset, length;
> +
> +	pages_per_block = msblk->block_size >> PAGE_CACHE_SHIFT;
> +	pages_per_block = pages_per_block ? pages_per_block : 1;
> +
> +	bh = ra_priv->bh;
> +	block_size = ra_priv->block_size;
> +	nr_bh = ra_priv->nr_bh;
> +	block = ra_priv->block;
> +
> +	if (block_size == 0)
> +		return squashfs_hole_readpages(inode, bindex, page_list);
> +
> +	buffer = kcalloc(1 << (msblk->block_log - PAGE_CACHE_SHIFT),
> +					sizeof(void *), GFP_KERNEL);
> +	if (!buffer)
> +		goto out;
> +	ra_priv->buffer = buffer;
> +
> +	page_array = kcalloc(1 << (msblk->block_log - PAGE_CACHE_SHIFT),
> +					sizeof(struct page *), GFP_KERNEL);
> +	if (!page_array)
> +		goto release_buffer;
> +	ra_priv->page_array = page_array;
> +
> +	/* alloc buffer pages */
> +	for (j = 0; j < pages_per_block; j++) {
> +		page = list_entry(page_list->prev, struct page, lru);
> +		list_del(&page->lru);
> +		buffer[j] = kmap(page);
> +		page_array[j] = page;
> +	}
> +
> +	compressed = SQUASHFS_COMPRESSED_BLOCK(block_size);
> +	length = SQUASHFS_COMPRESSED_SIZE_BLOCK(block_size);
> +
> +	offset = block & ((1 << msblk->devblksize_log2) - 1);
> +	length = squashfs_decompress_block(inode->i_sb, compressed, buffer,
> +				bh, nr_bh, offset, length, msblk->block_size,
> +				pages_per_block);
> +
> +	for (j = 0; j < pages_per_block; j++) {
> +		page = page_array[j];
> +		flush_dcache_page(page);
> +		SetPageUptodate(page);
> +		lru_cache_add_file(page);
> +		if (!PageLocked(page))
> +			printk("unlock page %p j %d\n", page, j);
> +		unlock_page(page);
> +	}
> +
> +	ret = 0;
> +
> +release_buffer:
> +	if (ra_priv->buffer) {
> +		for (j = 0; j < pages_per_block; j++) {
> +			if (!ra_priv->buffer[j])
> +				break;
> +			kunmap(ra_priv->page_array[j]);
> +			page_cache_release(ra_priv->page_array[j]);
> +		}
> +		kfree(ra_priv->page_array);
> +	}
> +
> +	kfree(ra_priv->buffer);
> +out:
> +	return ret;
> +}
> +
> +/*
> + * Fill hole pages between page_index and last_page_index
> + * Return 0 if function is successful, otherwise, return 1
> + * All pages are locked and added into page cache so that caller should
> + * add them into LRU and unlock.
> + */
> +int hole_plugging(struct squashfs_sb_info *msblk, struct list_head *page_list,
> +				int start_bindex, int last_bindex,
> +				struct address_space *mapping)
> +{
> +	struct page *page, *tmp_page, *hpage, *tpage;
> +	int page_index, last_page_index;
> +	gfp_t gfp_mask = mapping_gfp_mask(mapping);
> +
> +	page_index = start_bindex << (msblk->block_log - PAGE_CACHE_SHIFT);
> +	last_page_index = ((last_bindex + 1) <<
> +			(msblk->block_log - PAGE_CACHE_SHIFT));
> +	
> +	hpage = list_entry(page_list->prev, struct page, lru);
> +	for (; page_index < hpage->index; page_index++) {
> +		struct page *new_page = page_cache_alloc_readahead(mapping);
> +		if (!new_page)
> +			return 1;
> +		new_page->index = page_index;
> +		list_add(&new_page->lru, &hpage->lru);
> +	}
> +
> +	tpage = list_entry(page_list->next, struct page, lru);
> +	page_index = tpage->index + 1;
> +	for (; page_index < last_page_index; page_index++) {
> +		struct page *new_page = page_cache_alloc_readahead(mapping);
> +		if (!new_page)
> +			return 1;
> +		new_page->index = page_index;
> +		list_add(&new_page->lru, page_list);
> +	}
> +
> +	list_for_each_entry_reverse(page, page_list, lru)
> +		if (add_to_page_cache(page, mapping, page->index, gfp_mask))
> +			goto remove_pagecache;
> +	return 0;
> +
> +remove_pagecache:
> +	list_for_each_entry_reverse(tmp_page, page_list, lru) {
> +		if (tmp_page == page)
> +			break;
> +		delete_from_page_cache(tmp_page);
> +		unlock_page(tmp_page);
> +	}
> +	return 1;
> +}
> +
> +struct decomp_work {
> +	struct inode *inode;
> +	int bindex;
> +	struct list_head list;
> +	struct list_head pages;
> +	struct squashfs_ra_private *ra_priv;
> +	gfp_t gfp_mask;
> +};
> +
> +void squashfs_decomp_work(struct work_struct *work)
> +{
> +	struct inode *inode;
> +	struct list_head *pages;
> +	struct squashfs_ra_private *ra_priv;
> +	struct decomp_work *decomp_work;
> +	gfp_t gfp_mask;
> +	int bindex;
> +	struct squashfs_sb_info *msblk =
> +		container_of(work, struct squashfs_sb_info, delay_work.work);
> +
> +	for (;;) {
> +		decomp_work = NULL;
> +		spin_lock(&msblk->decomp_lock);
> +		if (!list_empty(&msblk->decomp_list)) {
> +			decomp_work = list_entry(msblk->decomp_list.prev,
> +					struct decomp_work, list);
> +			list_del(&decomp_work->list);
> +		}
> +		spin_unlock(&msblk->decomp_lock);
> +		if (!decomp_work)
> +			return;
> +
> +		inode = decomp_work->inode;
> +		bindex = decomp_work->bindex;
> +		ra_priv = decomp_work->ra_priv;
> +		gfp_mask = decomp_work->gfp_mask;
> +		pages = &decomp_work->pages;
> +
> +		if (squashfs_ra_decompress(inode, bindex, ra_priv,
> +						gfp_mask, pages)) {
> +			struct page *page, *tmp;
> +			list_for_each_entry_safe_reverse(page, tmp,
> +							pages, lru) {
> +				list_del(&page->lru);
> +				delete_from_page_cache(page);
> +				unlock_page(page);
> +				page_cache_release(page);
> +			}
> +		}
> +
> +		kfree(ra_priv->bh);
> +		kfree(ra_priv);
> +		kfree(decomp_work);
> +	}
> +}
> +
> +static int move_pages(struct list_head *page_list, struct list_head *pages,
> +				int nr)
> +{
> +	int moved_pages = 0;
> +	struct page *page, *tmp_page;
> +	list_for_each_entry_safe_reverse(page, tmp_page,
> +						page_list, lru) {
> +		list_move(&page->lru, pages);
> +		moved_pages++;
> +		if (moved_pages == nr)
> +			break;
> +	}
> +
> +	return moved_pages;
> +}
> +
> +static int squashfs_readpages(struct file *file, struct address_space *mapping,
> +		struct list_head *page_list, unsigned nr_pages)
> +{
> +	struct inode *inode = mapping->host;
> +	struct squashfs_sb_info *msblk = inode->i_sb->s_fs_info;
> +	struct page *hpage, *tpage, *page;
> +	struct decomp_work **work;
> +	int start_bindex, last_bindex;
> +	struct squashfs_ra_private **ra_priv;
> +	int pages_per_block, i, ret = -ENOMEM;
> +	gfp_t gfp_mask;
> +	int nr_blocks;
> +
> +	gfp_mask = mapping_gfp_mask(mapping);
> +
> +	hpage = list_entry(page_list->prev, struct page, lru);
> +	tpage = list_entry(page_list->next, struct page, lru);
> +
> +	start_bindex = hpage->index >> (msblk->block_log - PAGE_CACHE_SHIFT);
> +	last_bindex = tpage->index >> (msblk->block_log - PAGE_CACHE_SHIFT);
> +
> +	if (last_bindex >= (i_size_read(inode) >> msblk->block_log))
> +		return 0;
> +
> +	/* fill with pages for readahead  */
> +	if (hole_plugging(msblk, page_list, start_bindex,
> +					last_bindex, mapping)) {
> +		ret = 0;
> +		goto out;
> +	}
> +
> +	nr_blocks = last_bindex - start_bindex + 1;
> +	ra_priv = kcalloc(nr_blocks, sizeof(*ra_priv), GFP_KERNEL);
> +	if (!ra_priv)
> +		goto remove_pagecache;
> +
> +	for (i = 0; i < nr_blocks; i++) {
> +		ra_priv[i] = kmalloc(sizeof(**ra_priv),	GFP_KERNEL);
> +		if (ra_priv[i] == NULL)
> +			goto release_ra_priv;
> +	}
> +
> +	work = kcalloc(nr_blocks, sizeof(*work), GFP_KERNEL);
> +	if (!work)
> +		goto release_ra_priv;
> +
> +	for (i = 0; i < nr_blocks; i++) {
> +		work[i] = kmalloc(sizeof(**work), GFP_KERNEL);
> +		if (!work[i])
> +			goto release_work;
> +	}
> +
> +	for (i = 0; i < nr_blocks; i++) {
> +		ret = squashfs_ra_read_submit(inode, start_bindex + i ,
> +							ra_priv[i]);
> +		if (ret)
> +			goto release_ra_priv;
> +	}
> +
> +	ret = 0;
> +
> +	queue_delayed_work(system_unbound_wq, &msblk->delay_work,
> +		msecs_to_jiffies(3));
> +
> +	pages_per_block = msblk->block_size >> PAGE_CACHE_SHIFT;
> +	pages_per_block = pages_per_block ? pages_per_block : 1;
> +
> +	for (i = 0; i < nr_blocks; i++) {
> +		struct decomp_work *decomp_work = work[i];
> +
> +		INIT_LIST_HEAD(&decomp_work->pages);
> +		decomp_work->bindex = start_bindex + i;
> +		decomp_work->ra_priv = ra_priv[i];
> +		decomp_work->gfp_mask = gfp_mask;
> +		decomp_work->inode = inode;
> +
> +		move_pages(page_list, &decomp_work->pages,
> +			pages_per_block);
> +
> +		spin_lock(&msblk->decomp_lock);
> +		list_add(&decomp_work->list, &msblk->decomp_list);
> +		spin_unlock(&msblk->decomp_lock);
> +	}
> +
> +	kfree(ra_priv);
> +	kfree(work);
> +
> +	return ret;
> +
> +release_work:
> +	for (i = 0; i < nr_blocks; i++)
> +		kfree(work[i]);
> +	kfree(work);
> +release_ra_priv:
> +	for (i = 0; i < nr_blocks; i++)
> +		kfree(ra_priv[i]);
> +	kfree(ra_priv);
> +remove_pagecache:
> +	list_for_each_entry_reverse(page, page_list, lru) {
> +		delete_from_page_cache(page);
> +		unlock_page(page);
> +	}
> +out:
> +	return ret;
> +}
> +
>  const struct address_space_operations squashfs_aops = {
> -	.readpage = squashfs_readpage
> +	.readpage = squashfs_readpage,
> +	.readpages = squashfs_readpages,
>  };
> diff --git a/fs/squashfs/squashfs.h b/fs/squashfs/squashfs.h
> index 4bb1f90..2de96a7 100644
> --- a/fs/squashfs/squashfs.h
> +++ b/fs/squashfs/squashfs.h
> @@ -34,6 +34,8 @@ extern int squashfs_read_metablock(struct super_block *, void **, u64, int,
>  				u64 *, int, int);
>  extern int squashfs_read_submit(struct super_block *, u64, int, int,
>  				struct buffer_head **, int *);
> +extern int squashfs_decompress_block(struct super_block *, int, void **,
> +			struct buffer_head **, int, int, int, int, int);
>  
>  /* cache.c */
>  extern struct squashfs_cache *squashfs_cache_init(char *, int, int);
> @@ -89,6 +91,7 @@ extern const struct export_operations squashfs_export_ops;
>  
>  /* file.c */
>  extern const struct address_space_operations squashfs_aops;
> +extern void squashfs_decomp_work(struct work_struct *work);
>  
>  /* inode.c */
>  extern const struct inode_operations squashfs_inode_ops;
> diff --git a/fs/squashfs/squashfs_fs_sb.h b/fs/squashfs/squashfs_fs_sb.h
> index 0a209e6..bdcc0f2 100644
> --- a/fs/squashfs/squashfs_fs_sb.h
> +++ b/fs/squashfs/squashfs_fs_sb.h
> @@ -79,5 +79,9 @@ struct squashfs_sb_info {
>  	wait_queue_head_t			decomp_wait_queue;
>  	int					nr_avail_decomp;
>  	unsigned short				flags;
> +
> +	struct delayed_work			delay_work;
> +	spinlock_t				decomp_lock;
> +	struct list_head			decomp_list;
>  };
>  #endif
> diff --git a/fs/squashfs/super.c b/fs/squashfs/super.c
> index 70aa9c4..78d12d6 100644
> --- a/fs/squashfs/super.c
> +++ b/fs/squashfs/super.c
> @@ -73,7 +73,6 @@ static const struct squashfs_decompressor *supported_squashfs_filesystem(short
>  	return decompressor;
>  }
>  
> -
>  static int squashfs_fill_super(struct super_block *sb, void *data, int silent)
>  {
>  	struct squashfs_sb_info *msblk;
> @@ -98,6 +97,9 @@ static int squashfs_fill_super(struct super_block *sb, void *data, int silent)
>  	msblk->devblksize = sb_min_blocksize(sb, SQUASHFS_DEVBLK_SIZE);
>  	msblk->devblksize_log2 = ffz(~msblk->devblksize);
>  
> +	spin_lock_init(&msblk->decomp_lock);
> +	INIT_DELAYED_WORK(&msblk->delay_work, squashfs_decomp_work);
> +	INIT_LIST_HEAD(&msblk->decomp_list);
>  	INIT_LIST_HEAD(&msblk->strm_list);
>  	mutex_init(&msblk->comp_strm_mutex);
>  	init_waitqueue_head(&msblk->decomp_wait_queue);
> -- 
> 1.8.2.1
> 
> -- 
> Kind regards,
> Minchan Kim
> --
> To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
> the body of a message to majordomo@xxxxxxxxxxxxxxx
> More majordomo info at  http://vger.kernel.org/majordomo-info.html
> Please read the FAQ at  http://www.tux.org/lkml/

-- 
Kind regards,
Minchan Kim
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/