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Date:   Mon, 11 Jan 2021 01:48:00 -0800
From:   Jaegeuk Kim <jaegeuk@kernel.org>
To:     Chao Yu <yuchao0@huawei.com>
Cc:     linux-f2fs-devel@lists.sourceforge.net,
        linux-kernel@vger.kernel.org, chao@kernel.org
Subject: Re: [PATCH v3 1/5] f2fs: compress: add compress_inode to cache
 compressed blocks
Message-ID: <X/we0NoUqAwuW82+@google.com>
References: <20210107093126.116958-1-yuchao0@huawei.com>
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In-Reply-To: <20210107093126.116958-1-yuchao0@huawei.com>
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Hi Chao,

After quick test of fsstress w/ fault injection, it gave wrong block address
errors. Could you please run the test a bit?

Thanks,

On 01/07, Chao Yu wrote:
> Support to use address space of inner inode to cache compressed block,
> in order to improve cache hit ratio of random read.
> 
> Signed-off-by: Chao Yu <yuchao0@huawei.com>
> ---
> v3:
> - rebase to last dev branch.
> - add blkaddr sanity check in f2fs_cache_compressed_page()
>  Documentation/filesystems/f2fs.rst |   3 +
>  fs/f2fs/compress.c                 | 171 ++++++++++++++++++++++++++++-
>  fs/f2fs/data.c                     |  19 +++-
>  fs/f2fs/debug.c                    |  13 +++
>  fs/f2fs/f2fs.h                     |  39 ++++++-
>  fs/f2fs/gc.c                       |   1 +
>  fs/f2fs/inode.c                    |  21 +++-
>  fs/f2fs/segment.c                  |   6 +-
>  fs/f2fs/super.c                    |  19 +++-
>  include/linux/f2fs_fs.h            |   1 +
>  10 files changed, 282 insertions(+), 11 deletions(-)
> 
> diff --git a/Documentation/filesystems/f2fs.rst b/Documentation/filesystems/f2fs.rst
> index 5eff4009e77e..cd1e5b826ba3 100644
> --- a/Documentation/filesystems/f2fs.rst
> +++ b/Documentation/filesystems/f2fs.rst
> @@ -273,6 +273,9 @@ compress_mode=%s	 Control file compression mode. This supports "fs" and "user"
>  			 choosing the target file and the timing. The user can do manual
>  			 compression/decompression on the compression enabled files using
>  			 ioctls.
> +compress_cache		 Support to use address space of a filesystem managed inode to
> +			 cache compressed block, in order to improve cache hit ratio of
> +			 random read.
>  inlinecrypt		 When possible, encrypt/decrypt the contents of encrypted
>  			 files using the blk-crypto framework rather than
>  			 filesystem-layer encryption. This allows the use of
> diff --git a/fs/f2fs/compress.c b/fs/f2fs/compress.c
> index 1696f9183ff5..cb16b0437bd4 100644
> --- a/fs/f2fs/compress.c
> +++ b/fs/f2fs/compress.c
> @@ -12,9 +12,11 @@
>  #include <linux/lzo.h>
>  #include <linux/lz4.h>
>  #include <linux/zstd.h>
> +#include <linux/pagevec.h>
>  
>  #include "f2fs.h"
>  #include "node.h"
> +#include "segment.h"
>  #include <trace/events/f2fs.h>
>  
>  static struct kmem_cache *cic_entry_slab;
> @@ -756,7 +758,7 @@ static int f2fs_compress_pages(struct compress_ctx *cc)
>  	return ret;
>  }
>  
> -static void f2fs_decompress_cluster(struct decompress_io_ctx *dic)
> +void f2fs_decompress_cluster(struct decompress_io_ctx *dic)
>  {
>  	struct f2fs_sb_info *sbi = F2FS_I_SB(dic->inode);
>  	struct f2fs_inode_info *fi = F2FS_I(dic->inode);
> @@ -855,7 +857,8 @@ static void f2fs_decompress_cluster(struct decompress_io_ctx *dic)
>   * page being waited on in the cluster, and if so, it decompresses the cluster
>   * (or in the case of a failure, cleans up without actually decompressing).
>   */
> -void f2fs_end_read_compressed_page(struct page *page, bool failed)
> +void f2fs_end_read_compressed_page(struct page *page, bool failed,
> +						block_t blkaddr)
>  {
>  	struct decompress_io_ctx *dic =
>  			(struct decompress_io_ctx *)page_private(page);
> @@ -865,6 +868,9 @@ void f2fs_end_read_compressed_page(struct page *page, bool failed)
>  
>  	if (failed)
>  		WRITE_ONCE(dic->failed, true);
> +	else if (blkaddr)
> +		f2fs_cache_compressed_page(sbi, page,
> +					dic->inode->i_ino, blkaddr);
>  
>  	if (atomic_dec_and_test(&dic->remaining_pages))
>  		f2fs_decompress_cluster(dic);
> @@ -1702,6 +1708,167 @@ void f2fs_put_page_dic(struct page *page)
>  	f2fs_put_dic(dic);
>  }
>  
> +const struct address_space_operations f2fs_compress_aops = {
> +	.releasepage = f2fs_release_page,
> +	.invalidatepage = f2fs_invalidate_page,
> +};
> +
> +struct address_space *COMPRESS_MAPPING(struct f2fs_sb_info *sbi)
> +{
> +	return sbi->compress_inode->i_mapping;
> +}
> +
> +void f2fs_invalidate_compress_page(struct f2fs_sb_info *sbi, block_t blkaddr)
> +{
> +	if (!sbi->compress_inode)
> +		return;
> +	invalidate_mapping_pages(COMPRESS_MAPPING(sbi), blkaddr, blkaddr);
> +}
> +
> +void f2fs_cache_compressed_page(struct f2fs_sb_info *sbi, struct page *page,
> +						nid_t ino, block_t blkaddr)
> +{
> +	struct page *cpage;
> +	int ret;
> +	struct sysinfo si;
> +	unsigned long free_ram, avail_ram;
> +
> +	if (!test_opt(sbi, COMPRESS_CACHE))
> +		return;
> +
> +	if (!f2fs_is_valid_blkaddr(sbi, blkaddr, DATA_GENERIC_ENHANCE))
> +		return;
> +
> +	si_meminfo(&si);
> +	free_ram = si.freeram;
> +	avail_ram = si.totalram - si.totalhigh;
> +
> +	/* free memory is lower than watermark, deny caching compress page */
> +	if (free_ram <= sbi->compress_watermark / 100 * avail_ram)
> +		return;
> +
> +	/* cached page count exceed threshold, deny caching compress page */
> +	if (COMPRESS_MAPPING(sbi)->nrpages >=
> +			free_ram / 100 * sbi->compress_percent)
> +		return;
> +
> +	cpage = find_get_page(COMPRESS_MAPPING(sbi), blkaddr);
> +	if (cpage) {
> +		f2fs_put_page(cpage, 0);
> +		return;
> +	}
> +
> +	cpage = alloc_page(__GFP_IO);
> +	if (!cpage)
> +		return;
> +
> +	ret = add_to_page_cache_lru(cpage, COMPRESS_MAPPING(sbi),
> +						blkaddr, GFP_NOFS);
> +	if (ret) {
> +		f2fs_put_page(cpage, 0);
> +		return;
> +	}
> +
> +	memcpy(page_address(cpage), page_address(page), PAGE_SIZE);
> +	SetPageUptodate(cpage);
> +
> +	f2fs_set_page_private(cpage, ino);
> +
> +	f2fs_put_page(cpage, 1);
> +}
> +
> +void f2fs_load_compressed_page(struct f2fs_sb_info *sbi, struct page *page,
> +								block_t blkaddr)
> +{
> +	struct page *cpage;
> +
> +	if (!test_opt(sbi, COMPRESS_CACHE))
> +		return;
> +
> +	cpage = f2fs_pagecache_get_page(COMPRESS_MAPPING(sbi),
> +				blkaddr, FGP_LOCK | FGP_NOWAIT, GFP_NOFS);
> +	if (cpage) {
> +		if (PageUptodate(cpage)) {
> +			atomic_inc(&sbi->compress_page_hit);
> +			memcpy(page_address(page),
> +				page_address(cpage), PAGE_SIZE);
> +			SetPageUptodate(page);
> +		}
> +		f2fs_put_page(cpage, 1);
> +	}
> +}
> +
> +void f2fs_invalidate_compress_pages(struct f2fs_sb_info *sbi, nid_t ino)
> +{
> +	struct address_space *mapping = sbi->compress_inode->i_mapping;
> +	struct pagevec pvec;
> +	pgoff_t index = 0;
> +	pgoff_t end = MAX_BLKADDR(sbi);
> +
> +	pagevec_init(&pvec);
> +
> +	do {
> +		unsigned int nr_pages;
> +		int i;
> +
> +		nr_pages = pagevec_lookup_range(&pvec, mapping,
> +						&index, end - 1);
> +		if (!nr_pages)
> +			break;
> +
> +		for (i = 0; i < nr_pages; i++) {
> +			struct page *page = pvec.pages[i];
> +
> +			if (page->index > end)
> +				break;
> +
> +			lock_page(page);
> +			if (page->mapping != mapping) {
> +				unlock_page(page);
> +				continue;
> +			}
> +
> +			if (ino != page_private(page)) {
> +				unlock_page(page);
> +				continue;
> +			}
> +
> +			generic_error_remove_page(mapping, page);
> +			unlock_page(page);
> +		}
> +		pagevec_release(&pvec);
> +		cond_resched();
> +	} while (index < end);
> +}
> +
> +int f2fs_init_compress_inode(struct f2fs_sb_info *sbi)
> +{
> +	struct inode *inode;
> +
> +	if (!test_opt(sbi, COMPRESS_CACHE))
> +		return 0;
> +
> +	inode = f2fs_iget(sbi->sb, F2FS_COMPRESS_INO(sbi));
> +	if (IS_ERR(inode))
> +		return PTR_ERR(inode);
> +	sbi->compress_inode = inode;
> +
> +	sbi->compress_percent = COMPRESS_PERCENT;
> +	sbi->compress_watermark = COMPRESS_WATERMARK;
> +
> +	atomic_set(&sbi->compress_page_hit, 0);
> +
> +	return 0;
> +}
> +
> +void f2fs_destroy_compress_inode(struct f2fs_sb_info *sbi)
> +{
> +	if (!sbi->compress_inode)
> +		return;
> +	iput(sbi->compress_inode);
> +	sbi->compress_inode = NULL;
> +}
> +
>  int f2fs_init_page_array_cache(struct f2fs_sb_info *sbi)
>  {
>  	dev_t dev = sbi->sb->s_bdev->bd_dev;
> diff --git a/fs/f2fs/data.c b/fs/f2fs/data.c
> index 4d80f00e5e40..427a527eb17e 100644
> --- a/fs/f2fs/data.c
> +++ b/fs/f2fs/data.c
> @@ -153,7 +153,7 @@ static void f2fs_finish_read_bio(struct bio *bio)
>  
>  		if (f2fs_is_compressed_page(page)) {
>  			if (bio->bi_status)
> -				f2fs_end_read_compressed_page(page, true);
> +				f2fs_end_read_compressed_page(page, true, 0);
>  			f2fs_put_page_dic(page);
>  			continue;
>  		}
> @@ -249,15 +249,19 @@ static void f2fs_handle_step_decompress(struct bio_post_read_ctx *ctx)
>  	struct bio_vec *bv;
>  	struct bvec_iter_all iter_all;
>  	bool all_compressed = true;
> +	block_t blkaddr = SECTOR_TO_BLOCK(ctx->bio->bi_iter.bi_sector);
>  
>  	bio_for_each_segment_all(bv, ctx->bio, iter_all) {
>  		struct page *page = bv->bv_page;
>  
>  		/* PG_error was set if decryption failed. */
>  		if (f2fs_is_compressed_page(page))
> -			f2fs_end_read_compressed_page(page, PageError(page));
> +			f2fs_end_read_compressed_page(page, PageError(page),
> +						blkaddr);
>  		else
>  			all_compressed = false;
> +
> +		blkaddr++;
>  	}
>  
>  	/*
> @@ -1385,9 +1389,11 @@ static int __allocate_data_block(struct dnode_of_data *dn, int seg_type)
>  	old_blkaddr = dn->data_blkaddr;
>  	f2fs_allocate_data_block(sbi, NULL, old_blkaddr, &dn->data_blkaddr,
>  				&sum, seg_type, NULL);
> -	if (GET_SEGNO(sbi, old_blkaddr) != NULL_SEGNO)
> +	if (GET_SEGNO(sbi, old_blkaddr) != NULL_SEGNO) {
>  		invalidate_mapping_pages(META_MAPPING(sbi),
>  					old_blkaddr, old_blkaddr);
> +		f2fs_invalidate_compress_page(sbi, old_blkaddr);
> +	}
>  	f2fs_update_data_blkaddr(dn, dn->data_blkaddr);
>  
>  	/*
> @@ -2205,6 +2211,13 @@ int f2fs_read_multi_pages(struct compress_ctx *cc, struct bio **bio_ret,
>  		blkaddr = data_blkaddr(dn.inode, dn.node_page,
>  						dn.ofs_in_node + i + 1);
>  
> +		f2fs_load_compressed_page(sbi, page, blkaddr);
> +		if (PageUptodate(page)) {
> +			if (atomic_dec_and_test(&dic->remaining_pages))
> +				f2fs_decompress_cluster(dic);
> +			continue;
> +		}
> +
>  		if (bio && (!page_is_mergeable(sbi, bio,
>  					*last_block_in_bio, blkaddr) ||
>  		    !f2fs_crypt_mergeable_bio(bio, inode, page->index, NULL))) {
> diff --git a/fs/f2fs/debug.c b/fs/f2fs/debug.c
> index 197c914119da..f1f8714066c5 100644
> --- a/fs/f2fs/debug.c
> +++ b/fs/f2fs/debug.c
> @@ -145,6 +145,12 @@ static void update_general_status(struct f2fs_sb_info *sbi)
>  		si->node_pages = NODE_MAPPING(sbi)->nrpages;
>  	if (sbi->meta_inode)
>  		si->meta_pages = META_MAPPING(sbi)->nrpages;
> +#ifdef CONFIG_F2FS_FS_COMPRESSION
> +	if (sbi->compress_inode) {
> +		si->compress_pages = COMPRESS_MAPPING(sbi)->nrpages;
> +		si->compress_page_hit = atomic_read(&sbi->compress_page_hit);
> +	}
> +#endif
>  	si->nats = NM_I(sbi)->nat_cnt[TOTAL_NAT];
>  	si->dirty_nats = NM_I(sbi)->nat_cnt[DIRTY_NAT];
>  	si->sits = MAIN_SEGS(sbi);
> @@ -299,6 +305,12 @@ static void update_mem_info(struct f2fs_sb_info *sbi)
>  		unsigned npages = META_MAPPING(sbi)->nrpages;
>  		si->page_mem += (unsigned long long)npages << PAGE_SHIFT;
>  	}
> +#ifdef CONFIG_F2FS_FS_COMPRESSION
> +	if (sbi->compress_inode) {
> +		unsigned npages = COMPRESS_MAPPING(sbi)->nrpages;
> +		si->page_mem += (unsigned long long)npages << PAGE_SHIFT;
> +	}
> +#endif
>  }
>  
>  static int stat_show(struct seq_file *s, void *v)
> @@ -461,6 +473,7 @@ static int stat_show(struct seq_file *s, void *v)
>  			"volatile IO: %4d (Max. %4d)\n",
>  			   si->inmem_pages, si->aw_cnt, si->max_aw_cnt,
>  			   si->vw_cnt, si->max_vw_cnt);
> +		seq_printf(s, "  - compress: %4d, hit:%8d\n", si->compress_pages, si->compress_page_hit);
>  		seq_printf(s, "  - nodes: %4d in %4d\n",
>  			   si->ndirty_node, si->node_pages);
>  		seq_printf(s, "  - dents: %4d in dirs:%4d (%4d)\n",
> diff --git a/fs/f2fs/f2fs.h b/fs/f2fs/f2fs.h
> index 980e061f7968..67086c6072ad 100644
> --- a/fs/f2fs/f2fs.h
> +++ b/fs/f2fs/f2fs.h
> @@ -97,6 +97,7 @@ extern const char *f2fs_fault_name[FAULT_MAX];
>  #define F2FS_MOUNT_DISABLE_CHECKPOINT	0x02000000
>  #define F2FS_MOUNT_NORECOVERY		0x04000000
>  #define F2FS_MOUNT_ATGC			0x08000000
> +#define F2FS_MOUNT_COMPRESS_CACHE	0x10000000
>  
>  #define F2FS_OPTION(sbi)	((sbi)->mount_opt)
>  #define clear_opt(sbi, option)	(F2FS_OPTION(sbi).opt &= ~F2FS_MOUNT_##option)
> @@ -1300,6 +1301,9 @@ enum compress_flag {
>  	COMPRESS_MAX_FLAG,
>  };
>  
> +#define	COMPRESS_WATERMARK			20
> +#define	COMPRESS_PERCENT			20
> +
>  #define COMPRESS_DATA_RESERVED_SIZE		4
>  struct compress_data {
>  	__le32 clen;			/* compressed data size */
> @@ -1604,6 +1608,11 @@ struct f2fs_sb_info {
>  #ifdef CONFIG_F2FS_FS_COMPRESSION
>  	struct kmem_cache *page_array_slab;	/* page array entry */
>  	unsigned int page_array_slab_size;	/* default page array slab size */
> +
> +	struct inode *compress_inode;		/* cache compressed blocks */
> +	unsigned int compress_percent;		/* cache page percentage */
> +	unsigned int compress_watermark;	/* cache page watermark */
> +	atomic_t compress_page_hit;		/* cache hit count */
>  #endif
>  };
>  
> @@ -3571,7 +3580,8 @@ struct f2fs_stat_info {
>  	unsigned int bimodal, avg_vblocks;
>  	int util_free, util_valid, util_invalid;
>  	int rsvd_segs, overp_segs;
> -	int dirty_count, node_pages, meta_pages;
> +	int dirty_count, node_pages, meta_pages, compress_pages;
> +	int compress_page_hit;
>  	int prefree_count, call_count, cp_count, bg_cp_count;
>  	int tot_segs, node_segs, data_segs, free_segs, free_secs;
>  	int bg_node_segs, bg_data_segs;
> @@ -3909,7 +3919,9 @@ void f2fs_compress_write_end_io(struct bio *bio, struct page *page);
>  bool f2fs_is_compress_backend_ready(struct inode *inode);
>  int f2fs_init_compress_mempool(void);
>  void f2fs_destroy_compress_mempool(void);
> -void f2fs_end_read_compressed_page(struct page *page, bool failed);
> +void f2fs_decompress_cluster(struct decompress_io_ctx *dic);
> +void f2fs_end_read_compressed_page(struct page *page, bool failed,
> +							block_t blkaddr);
>  bool f2fs_cluster_is_empty(struct compress_ctx *cc);
>  bool f2fs_cluster_can_merge_page(struct compress_ctx *cc, pgoff_t index);
>  void f2fs_compress_ctx_add_page(struct compress_ctx *cc, struct page *page);
> @@ -3927,10 +3939,19 @@ void f2fs_put_page_dic(struct page *page);
>  int f2fs_init_compress_ctx(struct compress_ctx *cc);
>  void f2fs_destroy_compress_ctx(struct compress_ctx *cc);
>  void f2fs_init_compress_info(struct f2fs_sb_info *sbi);
> +int f2fs_init_compress_inode(struct f2fs_sb_info *sbi);
> +void f2fs_destroy_compress_inode(struct f2fs_sb_info *sbi);
>  int f2fs_init_page_array_cache(struct f2fs_sb_info *sbi);
>  void f2fs_destroy_page_array_cache(struct f2fs_sb_info *sbi);
>  int __init f2fs_init_compress_cache(void);
>  void f2fs_destroy_compress_cache(void);
> +struct address_space *COMPRESS_MAPPING(struct f2fs_sb_info *sbi);
> +void f2fs_invalidate_compress_page(struct f2fs_sb_info *sbi, block_t blkaddr);
> +void f2fs_cache_compressed_page(struct f2fs_sb_info *sbi, struct page *page,
> +						nid_t ino, block_t blkaddr);
> +void f2fs_load_compressed_page(struct f2fs_sb_info *sbi, struct page *page,
> +								block_t blkaddr);
> +void f2fs_invalidate_compress_pages(struct f2fs_sb_info *sbi, nid_t ino);
>  #else
>  static inline bool f2fs_is_compressed_page(struct page *page) { return false; }
>  static inline bool f2fs_is_compress_backend_ready(struct inode *inode)
> @@ -3947,7 +3968,9 @@ static inline struct page *f2fs_compress_control_page(struct page *page)
>  }
>  static inline int f2fs_init_compress_mempool(void) { return 0; }
>  static inline void f2fs_destroy_compress_mempool(void) { }
> -static inline void f2fs_end_read_compressed_page(struct page *page, bool failed)
> +static inline void f2fs_decompress_cluster(struct decompress_io_ctx *dic) { }
> +static inline void f2fs_end_read_compressed_page(struct page *page,
> +						bool failed, block_t blkaddr)
>  {
>  	WARN_ON_ONCE(1);
>  }
> @@ -3955,10 +3978,20 @@ static inline void f2fs_put_page_dic(struct page *page)
>  {
>  	WARN_ON_ONCE(1);
>  }
> +static inline int f2fs_init_compress_inode(struct f2fs_sb_info *sbi) { return 0; }
> +static inline void f2fs_destroy_compress_inode(struct f2fs_sb_info *sbi) { }
>  static inline int f2fs_init_page_array_cache(struct f2fs_sb_info *sbi) { return 0; }
>  static inline void f2fs_destroy_page_array_cache(struct f2fs_sb_info *sbi) { }
>  static inline int __init f2fs_init_compress_cache(void) { return 0; }
>  static inline void f2fs_destroy_compress_cache(void) { }
> +static inline void f2fs_invalidate_compress_page(struct f2fs_sb_info *sbi,
> +				block_t blkaddr) { }
> +static inline void f2fs_cache_compressed_page(struct f2fs_sb_info *sbi,
> +				struct page *page, nid_t ino, block_t blkaddr) { }
> +static inline void f2fs_load_compressed_page(struct f2fs_sb_info *sbi,
> +				struct page *page, block_t blkaddr) { }
> +static inline void f2fs_invalidate_compress_pages(struct f2fs_sb_info *sbi,
> +							nid_t ino) { }
>  #endif
>  
>  static inline void set_compress_context(struct inode *inode)
> diff --git a/fs/f2fs/gc.c b/fs/f2fs/gc.c
> index 39330ad3c44e..4561c44dfa8f 100644
> --- a/fs/f2fs/gc.c
> +++ b/fs/f2fs/gc.c
> @@ -1226,6 +1226,7 @@ static int move_data_block(struct inode *inode, block_t bidx,
>  	f2fs_put_page(mpage, 1);
>  	invalidate_mapping_pages(META_MAPPING(fio.sbi),
>  				fio.old_blkaddr, fio.old_blkaddr);
> +	f2fs_invalidate_compress_page(fio.sbi, fio.old_blkaddr);
>  
>  	set_page_dirty(fio.encrypted_page);
>  	if (clear_page_dirty_for_io(fio.encrypted_page))
> diff --git a/fs/f2fs/inode.c b/fs/f2fs/inode.c
> index 349d9cb933ee..f030b9b79202 100644
> --- a/fs/f2fs/inode.c
> +++ b/fs/f2fs/inode.c
> @@ -18,6 +18,10 @@
>  
>  #include <trace/events/f2fs.h>
>  
> +#ifdef CONFIG_F2FS_FS_COMPRESSION
> +extern const struct address_space_operations f2fs_compress_aops;
> +#endif
> +
>  void f2fs_mark_inode_dirty_sync(struct inode *inode, bool sync)
>  {
>  	if (is_inode_flag_set(inode, FI_NEW_INODE))
> @@ -494,6 +498,11 @@ struct inode *f2fs_iget(struct super_block *sb, unsigned long ino)
>  	if (ino == F2FS_NODE_INO(sbi) || ino == F2FS_META_INO(sbi))
>  		goto make_now;
>  
> +#ifdef CONFIG_F2FS_FS_COMPRESSION
> +	if (ino == F2FS_COMPRESS_INO(sbi))
> +		goto make_now;
> +#endif
> +
>  	ret = do_read_inode(inode);
>  	if (ret)
>  		goto bad_inode;
> @@ -504,6 +513,12 @@ struct inode *f2fs_iget(struct super_block *sb, unsigned long ino)
>  	} else if (ino == F2FS_META_INO(sbi)) {
>  		inode->i_mapping->a_ops = &f2fs_meta_aops;
>  		mapping_set_gfp_mask(inode->i_mapping, GFP_NOFS);
> +	} else if (ino == F2FS_COMPRESS_INO(sbi)) {
> +#ifdef CONFIG_F2FS_FS_COMPRESSION
> +		inode->i_mapping->a_ops = &f2fs_compress_aops;
> +#endif
> +		mapping_set_gfp_mask(inode->i_mapping,
> +			GFP_NOFS | __GFP_HIGHMEM | __GFP_MOVABLE);
>  	} else if (S_ISREG(inode->i_mode)) {
>  		inode->i_op = &f2fs_file_inode_operations;
>  		inode->i_fop = &f2fs_file_operations;
> @@ -722,8 +737,12 @@ void f2fs_evict_inode(struct inode *inode)
>  	trace_f2fs_evict_inode(inode);
>  	truncate_inode_pages_final(&inode->i_data);
>  
> +	if (test_opt(sbi, COMPRESS_CACHE) && f2fs_compressed_file(inode))
> +		f2fs_invalidate_compress_pages(sbi, inode->i_ino);
> +
>  	if (inode->i_ino == F2FS_NODE_INO(sbi) ||
> -			inode->i_ino == F2FS_META_INO(sbi))
> +			inode->i_ino == F2FS_META_INO(sbi) ||
> +			inode->i_ino == F2FS_COMPRESS_INO(sbi))
>  		goto out_clear;
>  
>  	f2fs_bug_on(sbi, get_dirty_pages(inode));
> diff --git a/fs/f2fs/segment.c b/fs/f2fs/segment.c
> index 11b2bba01353..dab870d9faf6 100644
> --- a/fs/f2fs/segment.c
> +++ b/fs/f2fs/segment.c
> @@ -2312,6 +2312,7 @@ void f2fs_invalidate_blocks(struct f2fs_sb_info *sbi, block_t addr)
>  		return;
>  
>  	invalidate_mapping_pages(META_MAPPING(sbi), addr, addr);
> +	f2fs_invalidate_compress_page(sbi, addr);
>  
>  	/* add it into sit main buffer */
>  	down_write(&sit_i->sentry_lock);
> @@ -3439,9 +3440,11 @@ static void do_write_page(struct f2fs_summary *sum, struct f2fs_io_info *fio)
>  reallocate:
>  	f2fs_allocate_data_block(fio->sbi, fio->page, fio->old_blkaddr,
>  			&fio->new_blkaddr, sum, type, fio);
> -	if (GET_SEGNO(fio->sbi, fio->old_blkaddr) != NULL_SEGNO)
> +	if (GET_SEGNO(fio->sbi, fio->old_blkaddr) != NULL_SEGNO) {
>  		invalidate_mapping_pages(META_MAPPING(fio->sbi),
>  					fio->old_blkaddr, fio->old_blkaddr);
> +		f2fs_invalidate_compress_page(fio->sbi, fio->old_blkaddr);
> +	}
>  
>  	/* writeout dirty page into bdev */
>  	f2fs_submit_page_write(fio);
> @@ -3614,6 +3617,7 @@ void f2fs_do_replace_block(struct f2fs_sb_info *sbi, struct f2fs_summary *sum,
>  	if (GET_SEGNO(sbi, old_blkaddr) != NULL_SEGNO) {
>  		invalidate_mapping_pages(META_MAPPING(sbi),
>  					old_blkaddr, old_blkaddr);
> +		f2fs_invalidate_compress_page(sbi, old_blkaddr);
>  		if (!from_gc)
>  			update_segment_mtime(sbi, old_blkaddr, 0);
>  		update_sit_entry(sbi, old_blkaddr, -1);
> diff --git a/fs/f2fs/super.c b/fs/f2fs/super.c
> index c39c03ac7468..18d9a7ece24d 100644
> --- a/fs/f2fs/super.c
> +++ b/fs/f2fs/super.c
> @@ -150,6 +150,7 @@ enum {
>  	Opt_compress_extension,
>  	Opt_compress_chksum,
>  	Opt_compress_mode,
> +	Opt_compress_cache,
>  	Opt_atgc,
>  	Opt_err,
>  };
> @@ -220,6 +221,7 @@ static match_table_t f2fs_tokens = {
>  	{Opt_compress_extension, "compress_extension=%s"},
>  	{Opt_compress_chksum, "compress_chksum"},
>  	{Opt_compress_mode, "compress_mode=%s"},
> +	{Opt_compress_cache, "compress_cache"},
>  	{Opt_atgc, "atgc"},
>  	{Opt_err, NULL},
>  };
> @@ -1035,12 +1037,16 @@ static int parse_options(struct super_block *sb, char *options, bool is_remount)
>  			}
>  			kfree(name);
>  			break;
> +		case Opt_compress_cache:
> +			set_opt(sbi, COMPRESS_CACHE);
> +			break;
>  #else
>  		case Opt_compress_algorithm:
>  		case Opt_compress_log_size:
>  		case Opt_compress_extension:
>  		case Opt_compress_chksum:
>  		case Opt_compress_mode:
> +		case Opt_compress_cache:
>  			f2fs_info(sbi, "compression options not supported");
>  			break;
>  #endif
> @@ -1365,6 +1371,8 @@ static void f2fs_put_super(struct super_block *sb)
>  
>  	f2fs_bug_on(sbi, sbi->fsync_node_num);
>  
> +	f2fs_destroy_compress_inode(sbi);
> +
>  	iput(sbi->node_inode);
>  	sbi->node_inode = NULL;
>  
> @@ -1637,6 +1645,9 @@ static inline void f2fs_show_compress_options(struct seq_file *seq,
>  		seq_printf(seq, ",compress_mode=%s", "fs");
>  	else if (F2FS_OPTION(sbi).compress_mode == COMPR_MODE_USER)
>  		seq_printf(seq, ",compress_mode=%s", "user");
> +
> +	if (test_opt(sbi, COMPRESS_CACHE))
> +		seq_puts(seq, ",compress_cache");
>  }
>  
>  static int f2fs_show_options(struct seq_file *seq, struct dentry *root)
> @@ -3841,10 +3852,14 @@ static int f2fs_fill_super(struct super_block *sb, void *data, int silent)
>  		goto free_node_inode;
>  	}
>  
> -	err = f2fs_register_sysfs(sbi);
> +	err = f2fs_init_compress_inode(sbi);
>  	if (err)
>  		goto free_root_inode;
>  
> +	err = f2fs_register_sysfs(sbi);
> +	if (err)
> +		goto free_compress_inode;
> +
>  #ifdef CONFIG_QUOTA
>  	/* Enable quota usage during mount */
>  	if (f2fs_sb_has_quota_ino(sbi) && !f2fs_readonly(sb)) {
> @@ -3978,6 +3993,8 @@ static int f2fs_fill_super(struct super_block *sb, void *data, int silent)
>  	/* evict some inodes being cached by GC */
>  	evict_inodes(sb);
>  	f2fs_unregister_sysfs(sbi);
> +free_compress_inode:
> +	f2fs_destroy_compress_inode(sbi);
>  free_root_inode:
>  	dput(sb->s_root);
>  	sb->s_root = NULL;
> diff --git a/include/linux/f2fs_fs.h b/include/linux/f2fs_fs.h
> index c6cc0a566ef5..2dcc63fe8494 100644
> --- a/include/linux/f2fs_fs.h
> +++ b/include/linux/f2fs_fs.h
> @@ -34,6 +34,7 @@
>  #define F2FS_ROOT_INO(sbi)	((sbi)->root_ino_num)
>  #define F2FS_NODE_INO(sbi)	((sbi)->node_ino_num)
>  #define F2FS_META_INO(sbi)	((sbi)->meta_ino_num)
> +#define F2FS_COMPRESS_INO(sbi)	(NM_I(sbi)->max_nid)
>  
>  #define F2FS_MAX_QUOTAS		3
>  
> -- 
> 2.29.2