Re: [PATCH v6] f2fs: compress: add compress_inode to cache compressed blocks

[Jaegeuk Kim <jaegeuk@kernel.org>]

On 05/25, Chao Yu wrote:
> Also, and queue this?

Easy to get this?

[ 1204.287099] kworker/u17:0: page allocation failure: order:0, mode:0x40(__GFP_IO), nodemask=(null),cpuset=/,mems_allowed=0
[ 1204.296932] CPU: 1 PID: 158 Comm: kworker/u17:0 Tainted: G           OE     5.13.0-rc1-custom #1
[ 1204.300746] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.14.0-2 04/01/2014
[ 1204.303458] Workqueue: f2fs_post_read_wq f2fs_post_read_work [f2fs]
[ 1204.305772] Call Trace:
[ 1204.307103]  dump_stack+0x7d/0x9c
[ 1204.308613]  warn_alloc.cold+0x7b/0xdf
[ 1204.310167]  __alloc_pages_slowpath.constprop.0+0xd57/0xd80
[ 1204.312214]  __alloc_pages+0x30e/0x330
[ 1204.313780]  alloc_pages+0x87/0x110
[ 1204.315265]  f2fs_cache_compressed_page+0x136/0x2d0 [f2fs]
[ 1204.317142]  ? dequeue_entity+0xdb/0x450
[ 1204.318708]  f2fs_end_read_compressed_page+0x5c/0x70 [f2fs]
[ 1204.320659]  f2fs_post_read_work+0x11f/0x180 [f2fs]
[ 1204.322442]  process_one_work+0x220/0x3c0
[ 1204.324091]  worker_thread+0x53/0x420
[ 1204.325577]  kthread+0x12f/0x150

> 
> On 2021/5/20 19:51, Chao Yu wrote:
> > From: Chao Yu <yuchao0@huawei.com>
> > 
> > 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>
> > ---
> > v6:
> > - fix to cover COMPRESS_MAPPING() with CONFIG_F2FS_FS_COMPRESSION
> >   Documentation/filesystems/f2fs.rst |   3 +
> >   fs/f2fs/compress.c                 | 180 ++++++++++++++++++++++++++++-
> >   fs/f2fs/data.c                     |  41 ++++++-
> >   fs/f2fs/debug.c                    |  13 +++
> >   fs/f2fs/f2fs.h                     |  71 +++++++++++-
> >   fs/f2fs/gc.c                       |   1 +
> >   fs/f2fs/inode.c                    |  21 +++-
> >   fs/f2fs/segment.c                  |   6 +-
> >   fs/f2fs/super.c                    |  35 +++++-
> >   include/linux/f2fs_fs.h            |   1 +
> >   10 files changed, 358 insertions(+), 14 deletions(-)
> > 
> > diff --git a/Documentation/filesystems/f2fs.rst b/Documentation/filesystems/f2fs.rst
> > index 992bf91eeec8..809c4d0a696f 100644
> > --- a/Documentation/filesystems/f2fs.rst
> > +++ b/Documentation/filesystems/f2fs.rst
> > @@ -289,6 +289,9 @@ 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 d4f7371fb0d8..25e785e0d9fc 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;
> > @@ -736,7 +738,7 @@ 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);
> > @@ -835,7 +837,8 @@ 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);
> > @@ -845,6 +848,9 @@ 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);
> > @@ -1660,6 +1666,176 @@ 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_READ))
> > +		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;
> > +	}
> > +
> > +	set_page_private_data(cpage, ino);
> > +
> > +	if (!f2fs_is_valid_blkaddr(sbi, blkaddr, DATA_GENERIC_ENHANCE_READ))
> > +		goto out;
> > +
> > +	memcpy(page_address(cpage), page_address(page), PAGE_SIZE);
> > +	SetPageUptodate(cpage);
> > +out:
> > +	f2fs_put_page(cpage, 1);
> > +}
> > +
> > +bool f2fs_load_compressed_page(struct f2fs_sb_info *sbi, struct page *page,
> > +								block_t blkaddr)
> > +{
> > +	struct page *cpage;
> > +	bool hitted = false;
> > +
> > +	if (!test_opt(sbi, COMPRESS_CACHE))
> > +		return false;
> > +
> > +	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);
> > +			hitted = true;
> > +		}
> > +		f2fs_put_page(cpage, 1);
> > +	}
> > +
> > +	return hitted;
> > +}
> > +
> > +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);
> > +
> > +	if (!mapping->nrpages)
> > +		return;
> > +
> > +	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 != get_page_private_data(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 d4795eda12fa..3058c7e28b11 100644
> > --- a/fs/f2fs/data.c
> > +++ b/fs/f2fs/data.c
> > @@ -132,7 +132,7 @@ 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;
> >   		}
> > @@ -228,15 +228,19 @@ 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++;
> >   	}
> >   	/*
> > @@ -1352,9 +1356,11 @@ 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);
> >   	/*
> > @@ -2174,7 +2180,7 @@ int f2fs_read_multi_pages(struct compress_ctx *cc, struct bio **bio_ret,
> >   		goto out_put_dnode;
> >   	}
> > -	for (i = 0; i < dic->nr_cpages; i++) {
> > +	for (i = 0; i < cc->nr_cpages; i++) {
> >   		struct page *page = dic->cpages[i];
> >   		block_t blkaddr;
> >   		struct bio_post_read_ctx *ctx;
> > @@ -2182,6 +2188,14 @@ 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_wait_on_block_writeback(inode, blkaddr);
> > +
> > +		if (f2fs_load_compressed_page(sbi, page, blkaddr)) {
> > +			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))) {
> > @@ -2203,8 +2217,6 @@ int f2fs_read_multi_pages(struct compress_ctx *cc, struct bio **bio_ret,
> >   			}
> >   		}
> > -		f2fs_wait_on_block_writeback(inode, blkaddr);
> > -
> >   		if (bio_add_page(bio, page, blocksize, 0) < blocksize)
> >   			goto submit_and_realloc;
> > @@ -3618,6 +3630,13 @@ void f2fs_invalidate_page(struct page *page, unsigned int offset,
> >   	clear_page_private_gcing(page);
> > +	if (test_opt(sbi, COMPRESS_CACHE)) {
> > +		if (f2fs_compressed_file(inode))
> > +			f2fs_invalidate_compress_pages(sbi, inode->i_ino);
> > +		if (inode->i_ino == F2FS_COMPRESS_INO(sbi))
> > +			clear_page_private_data(page);
> > +	}
> > +
> >   	if (page_private_atomic(page))
> >   		return f2fs_drop_inmem_page(inode, page);
> > @@ -3635,6 +3654,16 @@ int f2fs_release_page(struct page *page, gfp_t wait)
> >   	if (page_private_atomic(page))
> >   		return 0;
> > +	if (test_opt(F2FS_P_SB(page), COMPRESS_CACHE)) {
> > +		struct f2fs_sb_info *sbi = F2FS_P_SB(page);
> > +		struct inode *inode = page->mapping->host;
> > +
> > +		if (f2fs_compressed_file(inode))
> > +			f2fs_invalidate_compress_pages(sbi, inode->i_ino);
> > +		if (inode->i_ino == F2FS_COMPRESS_INO(sbi))
> > +			clear_page_private_data(page);
> > +	}
> > +
> >   	clear_page_private_gcing(page);
> >   	detach_page_private(page);
> > diff --git a/fs/f2fs/debug.c b/fs/f2fs/debug.c
> > index c03949a7ccff..833325038ef3 100644
> > --- a/fs/f2fs/debug.c
> > +++ b/fs/f2fs/debug.c
> > @@ -152,6 +152,12 @@ 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);
> > @@ -309,6 +315,12 @@ static void update_mem_info(struct f2fs_sb_info *sbi)
> >   		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)
> > @@ -476,6 +488,7 @@ 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 c0bead0df66a..70c0bd563732 100644
> > --- a/fs/f2fs/f2fs.h
> > +++ b/fs/f2fs/f2fs.h
> > @@ -98,6 +98,7 @@ extern const char *f2fs_fault_name[FAULT_MAX];
> >   #define F2FS_MOUNT_ATGC			0x08000000
> >   #define F2FS_MOUNT_MERGE_CHECKPOINT	0x10000000
> >   #define	F2FS_MOUNT_GC_MERGE		0x20000000
> > +#define F2FS_MOUNT_COMPRESS_CACHE	0x40000000
> >   #define F2FS_OPTION(sbi)	((sbi)->mount_opt)
> >   #define clear_opt(sbi, option)	(F2FS_OPTION(sbi).opt &= ~F2FS_MOUNT_##option)
> > @@ -1371,6 +1372,37 @@ PAGE_PRIVATE_CLEAR_FUNC(gcing, ONGOING_MIGRATION);
> >   PAGE_PRIVATE_CLEAR_FUNC(atomic, ATOMIC_WRITE);
> >   PAGE_PRIVATE_CLEAR_FUNC(dummy, DUMMY_WRITE);
> > +static inline unsigned long get_page_private_data(struct page *page)
> > +{
> > +	unsigned long data = page_private(page);
> > +
> > +	if (!test_bit(PAGE_PRIVATE_NOT_POINTER, &data))
> > +		return 0;
> > +	return data >> PAGE_PRIVATE_MAX;
> > +}
> > +
> > +static inline void set_page_private_data(struct page *page, unsigned long data)
> > +{
> > +	if (!PagePrivate(page)) {
> > +		get_page(page);
> > +		SetPagePrivate(page);
> > +	}
> > +	set_bit(PAGE_PRIVATE_NOT_POINTER, &page_private(page));
> > +	page_private(page) |= data << PAGE_PRIVATE_MAX;
> > +}
> > +
> > +static inline void clear_page_private_data(struct page *page)
> > +{
> > +	page_private(page) &= (1 << PAGE_PRIVATE_MAX) - 1;
> > +	if (page_private(page) == 1 << PAGE_PRIVATE_NOT_POINTER) {
> > +		set_page_private(page, 0);
> > +		if (PagePrivate(page)) {
> > +			ClearPagePrivate(page);
> > +			put_page(page);
> > +		}
> > +	}
> > +}
> > +
> >   /* For compression */
> >   enum compress_algorithm_type {
> >   	COMPRESS_LZO,
> > @@ -1385,6 +1417,9 @@ 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 */
> > @@ -1694,6 +1729,12 @@ struct f2fs_sb_info {
> >   	u64 compr_written_block;
> >   	u64 compr_saved_block;
> >   	u32 compr_new_inode;
> > +
> > +	/* For compressed block cache */
> > +	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
> >   };
> > @@ -3660,7 +3701,8 @@ 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;
> > @@ -3996,7 +4038,9 @@ 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);
> > @@ -4014,10 +4058,19 @@ 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, bool reuse);
> >   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);
> > +bool 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);
> >   #define inc_compr_inode_stat(inode)					\
> >   	do {								\
> >   		struct f2fs_sb_info *sbi = F2FS_I_SB(inode);		\
> > @@ -4046,7 +4099,9 @@ 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);
> >   }
> > @@ -4054,10 +4109,20 @@ 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 bool f2fs_load_compressed_page(struct f2fs_sb_info *sbi,
> > +				struct page *page, block_t blkaddr) { return false; }
> > +static inline void f2fs_invalidate_compress_pages(struct f2fs_sb_info *sbi,
> > +							nid_t ino) { }
> >   #define inc_compr_inode_stat(inode)		do { } while (0)
> >   #endif
> > diff --git a/fs/f2fs/gc.c b/fs/f2fs/gc.c
> > index bcb3b488dbca..f3d2bed746b0 100644
> > --- a/fs/f2fs/gc.c
> > +++ b/fs/f2fs/gc.c
> > @@ -1261,6 +1261,7 @@ 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 cbda7ca3b3be..9141147b5bb0 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;
> > @@ -723,8 +738,12 @@ 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 8668df7870d0..406a6b244782 100644
> > --- a/fs/f2fs/segment.c
> > +++ b/fs/f2fs/segment.c
> > @@ -2322,6 +2322,7 @@ 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);
> > @@ -3469,9 +3470,11 @@ 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);
> > @@ -3661,6 +3664,7 @@ 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 096492caaa6b..5056b8cfe919 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_gc_merge,
> >   	Opt_nogc_merge,
> > @@ -224,6 +225,7 @@ 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_gc_merge, "gc_merge"},
> >   	{Opt_nogc_merge, "nogc_merge"},
> > @@ -1066,12 +1068,16 @@ 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
> > @@ -1403,6 +1409,8 @@ 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;
> > @@ -1672,6 +1680,9 @@ 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");
> >   }
> >   #endif
> > @@ -1949,6 +1960,7 @@ static int f2fs_remount(struct super_block *sb, int *flags, char *data)
> >   	bool disable_checkpoint = test_opt(sbi, DISABLE_CHECKPOINT);
> >   	bool no_io_align = !F2FS_IO_ALIGNED(sbi);
> >   	bool no_atgc = !test_opt(sbi, ATGC);
> > +	bool no_compress_cache = !test_opt(sbi, COMPRESS_CACHE);
> >   	bool checkpoint_changed;
> >   #ifdef CONFIG_QUOTA
> >   	int i, j;
> > @@ -2041,6 +2053,12 @@ static int f2fs_remount(struct super_block *sb, int *flags, char *data)
> >   		goto restore_opts;
> >   	}
> > +	if (no_compress_cache == !!test_opt(sbi, COMPRESS_CACHE)) {
> > +		err = -EINVAL;
> > +		f2fs_warn(sbi, "switch compress_cache option is not allowed");
> > +		goto restore_opts;
> > +	}
> > +
> >   	if ((*flags & SB_RDONLY) && test_opt(sbi, DISABLE_CHECKPOINT)) {
> >   		err = -EINVAL;
> >   		f2fs_warn(sbi, "disabling checkpoint not compatible with read-only");
> > @@ -3940,10 +3958,14 @@ 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)) {
> > @@ -4084,6 +4106,8 @@ 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;
> > @@ -4162,6 +4186,15 @@ static void kill_f2fs_super(struct super_block *sb)
> >   		f2fs_stop_gc_thread(sbi);
> >   		f2fs_stop_discard_thread(sbi);
> > +#ifdef CONFIG_F2FS_FS_COMPRESSION
> > +		/*
> > +		 * latter evict_inode() can bypass checking and invalidating
> > +		 * compress inode cache.
> > +		 */
> > +		if (test_opt(sbi, COMPRESS_CACHE))
> > +			truncate_inode_pages_final(COMPRESS_MAPPING(sbi));
> > +#endif
> > +
> >   		if (is_sbi_flag_set(sbi, SBI_IS_DIRTY) ||
> >   				!is_set_ckpt_flags(sbi, CP_UMOUNT_FLAG)) {
> >   			struct cp_control cpc = {
> > diff --git a/include/linux/f2fs_fs.h b/include/linux/f2fs_fs.h
> > index 5487a80617a3..0021ea8f7c3b 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
> >