text: // SPDX-License-Identifier: GPL-2.0
  /*
   * f2fs compress support
   *
   * Copyright (c) 2019 Chao Yu <chao@kernel.org>
   */
  
  #include <linux/fs.h>
  #include <linux/f2fs_fs.h>
  #include <linux/writeback.h>
  #include <linux/backing-dev.h>
  #include <linux/lzo.h>
  #include <linux/lz4.h>
  #include <linux/zstd.h>
  
  #include "f2fs.h"
  #include "node.h"
  #include <trace/events/f2fs.h>
  
  static struct kmem_cache *cic_entry_slab;
  static struct kmem_cache *dic_entry_slab;
  
  static void *page_array_alloc(struct inode *inode, int nr)
  {
  	struct f2fs_sb_info *sbi = F2FS_I_SB(inode);
  	unsigned int size = sizeof(struct page *) * nr;
  
  	if (likely(size <= sbi->page_array_slab_size))
  		return kmem_cache_zalloc(sbi->page_array_slab, GFP_NOFS);
  	return f2fs_kzalloc(sbi, size, GFP_NOFS);
  }
  
  static void page_array_free(struct inode *inode, void *pages, int nr)
  {
  	struct f2fs_sb_info *sbi = F2FS_I_SB(inode);
  	unsigned int size = sizeof(struct page *) * nr;
  
  	if (!pages)
  		return;
  
  	if (likely(size <= sbi->page_array_slab_size))
  		kmem_cache_free(sbi->page_array_slab, pages);
  	else
  		kfree(pages);
  }
  
  struct f2fs_compress_ops {
  	int (*init_compress_ctx)(struct compress_ctx *cc);
  	void (*destroy_compress_ctx)(struct compress_ctx *cc);
  	int (*compress_pages)(struct compress_ctx *cc);
  	int (*init_decompress_ctx)(struct decompress_io_ctx *dic);
  	void (*destroy_decompress_ctx)(struct decompress_io_ctx *dic);
  	int (*decompress_pages)(struct decompress_io_ctx *dic);
  };
  
  static unsigned int offset_in_cluster(struct compress_ctx *cc, pgoff_t index)
  {
  	return index & (cc->cluster_size - 1);
  }
  
  static pgoff_t cluster_idx(struct compress_ctx *cc, pgoff_t index)
  {
  	return index >> cc->log_cluster_size;
  }
  
  static pgoff_t start_idx_of_cluster(struct compress_ctx *cc)
  {
  	return cc->cluster_idx << cc->log_cluster_size;
  }
  
  bool f2fs_is_compressed_page(struct page *page)
  {
  	if (!PagePrivate(page))
  		return false;
  	if (!page_private(page))
  		return false;
  	if (IS_ATOMIC_WRITTEN_PAGE(page) || IS_DUMMY_WRITTEN_PAGE(page))
  		return false;
  	/*
  	 * page->private may be set with pid.
  	 * pid_max is enough to check if it is traced.
  	 */
  	if (IS_IO_TRACED_PAGE(page))
  		return false;
  
  	f2fs_bug_on(F2FS_M_SB(page->mapping),
  		*((u32 *)page_private(page)) != F2FS_COMPRESSED_PAGE_MAGIC);
  	return true;
  }
  
  static void f2fs_set_compressed_page(struct page *page,
  		struct inode *inode, pgoff_t index, void *data)
  {
  	SetPagePrivate(page);
  	set_page_private(page, (unsigned long)data);
  
  	/* i_crypto_info and iv index */
  	page->index = index;
  	page->mapping = inode->i_mapping;
  }
  
  static void f2fs_drop_rpages(struct compress_ctx *cc, int len, bool unlock)
  {
  	int i;
  
  	for (i = 0; i < len; i++) {
  		if (!cc->rpages[i])
  			continue;
  		if (unlock)
  			unlock_page(cc->rpages[i]);
  		else
  			put_page(cc->rpages[i]);
  	}
  }
  
  static void f2fs_put_rpages(struct compress_ctx *cc)
  {
  	f2fs_drop_rpages(cc, cc->cluster_size, false);
  }
  
  static void f2fs_unlock_rpages(struct compress_ctx *cc, int len)
  {
  	f2fs_drop_rpages(cc, len, true);
  }
  
  static void f2fs_put_rpages_wbc(struct compress_ctx *cc,
  		struct writeback_control *wbc, bool redirty, int unlock)
  {
  	unsigned int i;
  
  	for (i = 0; i < cc->cluster_size; i++) {
  		if (!cc->rpages[i])
  			continue;
  		if (redirty)
  			redirty_page_for_writepage(wbc, cc->rpages[i]);
  		f2fs_put_page(cc->rpages[i], unlock);
  	}
  }
  
  struct page *f2fs_compress_control_page(struct page *page)
  {
  	return ((struct compress_io_ctx *)page_private(page))->rpages[0];
  }
  
  int f2fs_init_compress_ctx(struct compress_ctx *cc)
  {
  	if (cc->rpages)
  		return 0;
  
  	cc->rpages = page_array_alloc(cc->inode, cc->cluster_size);
  	return cc->rpages ? 0 : -ENOMEM;
  }
  
  void f2fs_destroy_compress_ctx(struct compress_ctx *cc, bool reuse)
  {
  	page_array_free(cc->inode, cc->rpages, cc->cluster_size);
  	cc->rpages = NULL;
  	cc->nr_rpages = 0;
  	cc->nr_cpages = 0;
  	if (!reuse)
  		cc->cluster_idx = NULL_CLUSTER;
  }
  
  void f2fs_compress_ctx_add_page(struct compress_ctx *cc, struct page *page)
  {
  	unsigned int cluster_ofs;
  
  	if (!f2fs_cluster_can_merge_page(cc, page->index))
  		f2fs_bug_on(F2FS_I_SB(cc->inode), 1);
  
  	cluster_ofs = offset_in_cluster(cc, page->index);
  	cc->rpages[cluster_ofs] = page;
  	cc->nr_rpages++;
  	cc->cluster_idx = cluster_idx(cc, page->index);
  }
  
  #ifdef CONFIG_F2FS_FS_LZO
  static int lzo_init_compress_ctx(struct compress_ctx *cc)
  {
  	cc->private = f2fs_kvmalloc(F2FS_I_SB(cc->inode),
  				LZO1X_MEM_COMPRESS, GFP_NOFS);
  	if (!cc->private)
  		return -ENOMEM;
  
  	cc->clen = lzo1x_worst_compress(PAGE_SIZE << cc->log_cluster_size);
  	return 0;
  }
  
  static void lzo_destroy_compress_ctx(struct compress_ctx *cc)
  {
  	kvfree(cc->private);
  	cc->private = NULL;
  }
  
  static int lzo_compress_pages(struct compress_ctx *cc)
  {
  	int ret;
  
  	ret = lzo1x_1_compress(cc->rbuf, cc->rlen, cc->cbuf->cdata,
  					&cc->clen, cc->private);
  	if (ret != LZO_E_OK) {
  		printk_ratelimited("%sF2FS-fs (%s): lzo compress failed, ret:%d\n",
  				KERN_ERR, F2FS_I_SB(cc->inode)->sb->s_id, ret);
  		return -EIO;
  	}
  	return 0;
  }
  
  static int lzo_decompress_pages(struct decompress_io_ctx *dic)
  {
  	int ret;
  
  	ret = lzo1x_decompress_safe(dic->cbuf->cdata, dic->clen,
  						dic->rbuf, &dic->rlen);
  	if (ret != LZO_E_OK) {
  		printk_ratelimited("%sF2FS-fs (%s): lzo decompress failed, ret:%d\n",
  				KERN_ERR, F2FS_I_SB(dic->inode)->sb->s_id, ret);
  		return -EIO;
  	}
  
  	if (dic->rlen != PAGE_SIZE << dic->log_cluster_size) {
  		printk_ratelimited("%sF2FS-fs (%s): lzo invalid rlen:%zu, "
  					"expected:%lu\n", KERN_ERR,
  					F2FS_I_SB(dic->inode)->sb->s_id,
  					dic->rlen,
  					PAGE_SIZE << dic->log_cluster_size);
  		return -EIO;
  	}
  	return 0;
  }
  
  static const struct f2fs_compress_ops f2fs_lzo_ops = {
  	.init_compress_ctx	= lzo_init_compress_ctx,
  	.destroy_compress_ctx	= lzo_destroy_compress_ctx,
  	.compress_pages		= lzo_compress_pages,
  	.decompress_pages	= lzo_decompress_pages,
  };
  #endif
  
  #ifdef CONFIG_F2FS_FS_LZ4
  static int lz4_init_compress_ctx(struct compress_ctx *cc)
  {
  	unsigned int size = LZ4_MEM_COMPRESS;
  
  #ifdef CONFIG_F2FS_FS_LZ4HC
  	if (F2FS_I(cc->inode)->i_compress_flag >> COMPRESS_LEVEL_OFFSET)
  		size = LZ4HC_MEM_COMPRESS;
  #endif
  
  	cc->private = f2fs_kvmalloc(F2FS_I_SB(cc->inode), size, GFP_NOFS);
  	if (!cc->private)
  		return -ENOMEM;
  
  	/*
  	 * we do not change cc->clen to LZ4_compressBound(inputsize) to
  	 * adapt worst compress case, because lz4 compressor can handle
  	 * output budget properly.
  	 */
  	cc->clen = cc->rlen - PAGE_SIZE - COMPRESS_HEADER_SIZE;
  	return 0;
  }
  
  static void lz4_destroy_compress_ctx(struct compress_ctx *cc)
  {
  	kvfree(cc->private);
  	cc->private = NULL;
  }
  
  #ifdef CONFIG_F2FS_FS_LZ4HC
  static int lz4hc_compress_pages(struct compress_ctx *cc)
  {
  	unsigned char level = F2FS_I(cc->inode)->i_compress_flag >>
  						COMPRESS_LEVEL_OFFSET;
  	int len;
  
  	if (level)
  		len = LZ4_compress_HC(cc->rbuf, cc->cbuf->cdata, cc->rlen,
  					cc->clen, level, cc->private);
  	else
  		len = LZ4_compress_default(cc->rbuf, cc->cbuf->cdata, cc->rlen,
  						cc->clen, cc->private);
  	if (!len)
  		return -EAGAIN;
  
  	cc->clen = len;
  	return 0;
  }
  #endif
  
  static int lz4_compress_pages(struct compress_ctx *cc)
  {
  	int len;
  
  #ifdef CONFIG_F2FS_FS_LZ4HC
  	return lz4hc_compress_pages(cc);
  #endif
  	len = LZ4_compress_default(cc->rbuf, cc->cbuf->cdata, cc->rlen,
  						cc->clen, cc->private);
  	if (!len)
  		return -EAGAIN;
  
  	cc->clen = len;
  	return 0;
  }
  
  static int lz4_decompress_pages(struct decompress_io_ctx *dic)
  {
  	int ret;
  
  	ret = LZ4_decompress_safe(dic->cbuf->cdata, dic->rbuf,
  						dic->clen, dic->rlen);
  	if (ret < 0) {
  		printk_ratelimited("%sF2FS-fs (%s): lz4 decompress failed, ret:%d\n",
  				KERN_ERR, F2FS_I_SB(dic->inode)->sb->s_id, ret);
  		return -EIO;
  	}
  
  	if (ret != PAGE_SIZE << dic->log_cluster_size) {
  		printk_ratelimited("%sF2FS-fs (%s): lz4 invalid rlen:%zu, "
  					"expected:%lu\n", KERN_ERR,
  					F2FS_I_SB(dic->inode)->sb->s_id,
  					dic->rlen,
  					PAGE_SIZE << dic->log_cluster_size);
  		return -EIO;
  	}
  	return 0;
  }
  
  static const struct f2fs_compress_ops f2fs_lz4_ops = {
  	.init_compress_ctx	= lz4_init_compress_ctx,
  	.destroy_compress_ctx	= lz4_destroy_compress_ctx,
  	.compress_pages		= lz4_compress_pages,
  	.decompress_pages	= lz4_decompress_pages,
  };
  #endif
  
  #ifdef CONFIG_F2FS_FS_ZSTD
  #define F2FS_ZSTD_DEFAULT_CLEVEL	1
  
  static int zstd_init_compress_ctx(struct compress_ctx *cc)
  {
  	ZSTD_parameters params;
  	ZSTD_CStream *stream;
  	void *workspace;
  	unsigned int workspace_size;
  	unsigned char level = F2FS_I(cc->inode)->i_compress_flag >>
  						COMPRESS_LEVEL_OFFSET;
  
  	if (!level)
  		level = F2FS_ZSTD_DEFAULT_CLEVEL;
  
  	params = ZSTD_getParams(level, cc->rlen, 0);
  	workspace_size = ZSTD_CStreamWorkspaceBound(params.cParams);
  
  	workspace = f2fs_kvmalloc(F2FS_I_SB(cc->inode),
  					workspace_size, GFP_NOFS);
  	if (!workspace)
  		return -ENOMEM;
  
  	stream = ZSTD_initCStream(params, 0, workspace, workspace_size);
  	if (!stream) {
  		printk_ratelimited("%sF2FS-fs (%s): %s ZSTD_initCStream failed\n",
  				KERN_ERR, F2FS_I_SB(cc->inode)->sb->s_id,
  				__func__);
  		kvfree(workspace);
  		return -EIO;
  	}
  
  	cc->private = workspace;
  	cc->private2 = stream;
  
  	cc->clen = cc->rlen - PAGE_SIZE - COMPRESS_HEADER_SIZE;
  	return 0;
  }
  
  static void zstd_destroy_compress_ctx(struct compress_ctx *cc)
  {
  	kvfree(cc->private);
  	cc->private = NULL;
  	cc->private2 = NULL;
  }
  
  static int zstd_compress_pages(struct compress_ctx *cc)
  {
  	ZSTD_CStream *stream = cc->private2;
  	ZSTD_inBuffer inbuf;
  	ZSTD_outBuffer outbuf;
  	int src_size = cc->rlen;
  	int dst_size = src_size - PAGE_SIZE - COMPRESS_HEADER_SIZE;
  	int ret;
  
  	inbuf.pos = 0;
  	inbuf.src = cc->rbuf;
  	inbuf.size = src_size;
  
  	outbuf.pos = 0;
  	outbuf.dst = cc->cbuf->cdata;
  	outbuf.size = dst_size;
  
  	ret = ZSTD_compressStream(stream, &outbuf, &inbuf);
  	if (ZSTD_isError(ret)) {
  		printk_ratelimited("%sF2FS-fs (%s): %s ZSTD_compressStream failed, ret: %d\n",
  				KERN_ERR, F2FS_I_SB(cc->inode)->sb->s_id,
  				__func__, ZSTD_getErrorCode(ret));
  		return -EIO;
  	}
  
  	ret = ZSTD_endStream(stream, &outbuf);
  	if (ZSTD_isError(ret)) {
  		printk_ratelimited("%sF2FS-fs (%s): %s ZSTD_endStream returned %d\n",
  				KERN_ERR, F2FS_I_SB(cc->inode)->sb->s_id,
  				__func__, ZSTD_getErrorCode(ret));
  		return -EIO;
  	}
  
  	/*
  	 * there is compressed data remained in intermediate buffer due to
  	 * no more space in cbuf.cdata
  	 */
  	if (ret)
  		return -EAGAIN;
  
  	cc->clen = outbuf.pos;
  	return 0;
  }
  
  static int zstd_init_decompress_ctx(struct decompress_io_ctx *dic)
  {
  	ZSTD_DStream *stream;
  	void *workspace;
  	unsigned int workspace_size;
  	unsigned int max_window_size =
  			MAX_COMPRESS_WINDOW_SIZE(dic->log_cluster_size);
  
  	workspace_size = ZSTD_DStreamWorkspaceBound(max_window_size);
  
  	workspace = f2fs_kvmalloc(F2FS_I_SB(dic->inode),
  					workspace_size, GFP_NOFS);
  	if (!workspace)
  		return -ENOMEM;
  
  	stream = ZSTD_initDStream(max_window_size, workspace, workspace_size);
  	if (!stream) {
  		printk_ratelimited("%sF2FS-fs (%s): %s ZSTD_initDStream failed\n",
  				KERN_ERR, F2FS_I_SB(dic->inode)->sb->s_id,
  				__func__);
  		kvfree(workspace);
  		return -EIO;
  	}
  
  	dic->private = workspace;
  	dic->private2 = stream;
  
  	return 0;
  }
  
  static void zstd_destroy_decompress_ctx(struct decompress_io_ctx *dic)
  {
  	kvfree(dic->private);
  	dic->private = NULL;
  	dic->private2 = NULL;
  }
  
  static int zstd_decompress_pages(struct decompress_io_ctx *dic)
  {
  	ZSTD_DStream *stream = dic->private2;
  	ZSTD_inBuffer inbuf;
  	ZSTD_outBuffer outbuf;
  	int ret;
  
  	inbuf.pos = 0;
  	inbuf.src = dic->cbuf->cdata;
  	inbuf.size = dic->clen;
  
  	outbuf.pos = 0;
  	outbuf.dst = dic->rbuf;
  	outbuf.size = dic->rlen;
  
  	ret = ZSTD_decompressStream(stream, &outbuf, &inbuf);
  	if (ZSTD_isError(ret)) {
  		printk_ratelimited("%sF2FS-fs (%s): %s ZSTD_compressStream failed, ret: %d\n",
  				KERN_ERR, F2FS_I_SB(dic->inode)->sb->s_id,
  				__func__, ZSTD_getErrorCode(ret));
  		return -EIO;
  	}
  
  	if (dic->rlen != outbuf.pos) {
  		printk_ratelimited("%sF2FS-fs (%s): %s ZSTD invalid rlen:%zu, "
  				"expected:%lu\n", KERN_ERR,
  				F2FS_I_SB(dic->inode)->sb->s_id,
  				__func__, dic->rlen,
  				PAGE_SIZE << dic->log_cluster_size);
  		return -EIO;
  	}
  
  	return 0;
  }
  
  static const struct f2fs_compress_ops f2fs_zstd_ops = {
  	.init_compress_ctx	= zstd_init_compress_ctx,
  	.destroy_compress_ctx	= zstd_destroy_compress_ctx,
  	.compress_pages		= zstd_compress_pages,
  	.init_decompress_ctx	= zstd_init_decompress_ctx,
  	.destroy_decompress_ctx	= zstd_destroy_decompress_ctx,
  	.decompress_pages	= zstd_decompress_pages,
  };
  #endif
  
  #ifdef CONFIG_F2FS_FS_LZO
  #ifdef CONFIG_F2FS_FS_LZORLE
  static int lzorle_compress_pages(struct compress_ctx *cc)
  {
  	int ret;
  
  	ret = lzorle1x_1_compress(cc->rbuf, cc->rlen, cc->cbuf->cdata,
  					&cc->clen, cc->private);
  	if (ret != LZO_E_OK) {
  		printk_ratelimited("%sF2FS-fs (%s): lzo-rle compress failed, ret:%d\n",
  				KERN_ERR, F2FS_I_SB(cc->inode)->sb->s_id, ret);
  		return -EIO;
  	}
  	return 0;
  }
  
  static const struct f2fs_compress_ops f2fs_lzorle_ops = {
  	.init_compress_ctx	= lzo_init_compress_ctx,
  	.destroy_compress_ctx	= lzo_destroy_compress_ctx,
  	.compress_pages		= lzorle_compress_pages,
  	.decompress_pages	= lzo_decompress_pages,
  };
  #endif
  #endif
  
  static const struct f2fs_compress_ops *f2fs_cops[COMPRESS_MAX] = {
  #ifdef CONFIG_F2FS_FS_LZO
  	&f2fs_lzo_ops,
  #else
  	NULL,
  #endif
  #ifdef CONFIG_F2FS_FS_LZ4
  	&f2fs_lz4_ops,
  #else
  	NULL,
  #endif
  #ifdef CONFIG_F2FS_FS_ZSTD
  	&f2fs_zstd_ops,
  #else
  	NULL,
  #endif
  #if defined(CONFIG_F2FS_FS_LZO) && defined(CONFIG_F2FS_FS_LZORLE)
  	&f2fs_lzorle_ops,
  #else
  	NULL,
  #endif
  };
  
  bool f2fs_is_compress_backend_ready(struct inode *inode)
  {
  	if (!f2fs_compressed_file(inode))
  		return true;
  	return f2fs_cops[F2FS_I(inode)->i_compress_algorithm];
  }
  
  static mempool_t *compress_page_pool;
  static int num_compress_pages = 512;
  module_param(num_compress_pages, uint, 0444);
  MODULE_PARM_DESC(num_compress_pages,
  		"Number of intermediate compress pages to preallocate");
  
  int f2fs_init_compress_mempool(void)
  {
  	compress_page_pool = mempool_create_page_pool(num_compress_pages, 0);
  	if (!compress_page_pool)
  		return -ENOMEM;
  
  	return 0;
  }
  
  void f2fs_destroy_compress_mempool(void)
  {
  	mempool_destroy(compress_page_pool);
  }
  
  static struct page *f2fs_compress_alloc_page(void)
  {
  	struct page *page;
  
  	page = mempool_alloc(compress_page_pool, GFP_NOFS);
  	lock_page(page);
  
  	return page;
  }
  
  static void f2fs_compress_free_page(struct page *page)
  {
  	if (!page)
  		return;
  	set_page_private(page, (unsigned long)NULL);
  	ClearPagePrivate(page);
  	page->mapping = NULL;
  	unlock_page(page);
  	mempool_free(page, compress_page_pool);
  }
  
  #define MAX_VMAP_RETRIES	3
  
  static void *f2fs_vmap(struct page **pages, unsigned int count)
  {
  	int i;
  	void *buf = NULL;
  
  	for (i = 0; i < MAX_VMAP_RETRIES; i++) {
  		buf = vm_map_ram(pages, count, -1);
  		if (buf)
  			break;
  		vm_unmap_aliases();
  	}
  	return buf;
  }
  
  static int f2fs_compress_pages(struct compress_ctx *cc)
  {
  	struct f2fs_inode_info *fi = F2FS_I(cc->inode);
  	const struct f2fs_compress_ops *cops =
  				f2fs_cops[fi->i_compress_algorithm];
  	unsigned int max_len, new_nr_cpages;
  	struct page **new_cpages;
  	u32 chksum = 0;
  	int i, ret;
  
  	trace_f2fs_compress_pages_start(cc->inode, cc->cluster_idx,
  				cc->cluster_size, fi->i_compress_algorithm);
  
  	if (cops->init_compress_ctx) {
  		ret = cops->init_compress_ctx(cc);
  		if (ret)
  			goto out;
  	}
  
  	max_len = COMPRESS_HEADER_SIZE + cc->clen;
  	cc->nr_cpages = DIV_ROUND_UP(max_len, PAGE_SIZE);
  
  	cc->cpages = page_array_alloc(cc->inode, cc->nr_cpages);
  	if (!cc->cpages) {
  		ret = -ENOMEM;
  		goto destroy_compress_ctx;
  	}
  
  	for (i = 0; i < cc->nr_cpages; i++) {
  		cc->cpages[i] = f2fs_compress_alloc_page();
  		if (!cc->cpages[i]) {
  			ret = -ENOMEM;
  			goto out_free_cpages;
  		}
  	}
  
  	cc->rbuf = f2fs_vmap(cc->rpages, cc->cluster_size);
  	if (!cc->rbuf) {
  		ret = -ENOMEM;
  		goto out_free_cpages;
  	}
  
  	cc->cbuf = f2fs_vmap(cc->cpages, cc->nr_cpages);
  	if (!cc->cbuf) {
  		ret = -ENOMEM;
  		goto out_vunmap_rbuf;
  	}
  
  	ret = cops->compress_pages(cc);
  	if (ret)
  		goto out_vunmap_cbuf;
  
  	max_len = PAGE_SIZE * (cc->cluster_size - 1) - COMPRESS_HEADER_SIZE;
  
  	if (cc->clen > max_len) {
  		ret = -EAGAIN;
  		goto out_vunmap_cbuf;
  	}
  
  	cc->cbuf->clen = cpu_to_le32(cc->clen);
  
  	if (fi->i_compress_flag & 1 << COMPRESS_CHKSUM)
  		chksum = f2fs_crc32(F2FS_I_SB(cc->inode),
  					cc->cbuf->cdata, cc->clen);
  	cc->cbuf->chksum = cpu_to_le32(chksum);
  
  	for (i = 0; i < COMPRESS_DATA_RESERVED_SIZE; i++)
  		cc->cbuf->reserved[i] = cpu_to_le32(0);
  
  	new_nr_cpages = DIV_ROUND_UP(cc->clen + COMPRESS_HEADER_SIZE, PAGE_SIZE);
  
  	/* Now we're going to cut unnecessary tail pages */
  	new_cpages = page_array_alloc(cc->inode, new_nr_cpages);
  	if (!new_cpages) {
  		ret = -ENOMEM;
  		goto out_vunmap_cbuf;
  	}
  
  	/* zero out any unused part of the last page */
  	memset(&cc->cbuf->cdata[cc->clen], 0,
  			(new_nr_cpages * PAGE_SIZE) -
  			(cc->clen + COMPRESS_HEADER_SIZE));
  
  	vm_unmap_ram(cc->cbuf, cc->nr_cpages);
  	vm_unmap_ram(cc->rbuf, cc->cluster_size);
  
  	for (i = 0; i < cc->nr_cpages; i++) {
  		if (i < new_nr_cpages) {
  			new_cpages[i] = cc->cpages[i];
  			continue;
  		}
  		f2fs_compress_free_page(cc->cpages[i]);
  		cc->cpages[i] = NULL;
  	}
  
  	if (cops->destroy_compress_ctx)
  		cops->destroy_compress_ctx(cc);
  
  	page_array_free(cc->inode, cc->cpages, cc->nr_cpages);
  	cc->cpages = new_cpages;
  	cc->nr_cpages = new_nr_cpages;
  
  	trace_f2fs_compress_pages_end(cc->inode, cc->cluster_idx,
  							cc->clen, ret);
  	return 0;
  
  out_vunmap_cbuf:
  	vm_unmap_ram(cc->cbuf, cc->nr_cpages);
  out_vunmap_rbuf:
  	vm_unmap_ram(cc->rbuf, cc->cluster_size);
  out_free_cpages:
  	for (i = 0; i < cc->nr_cpages; i++) {
  		if (cc->cpages[i])
  			f2fs_compress_free_page(cc->cpages[i]);
  	}
  	page_array_free(cc->inode, cc->cpages, cc->nr_cpages);
  	cc->cpages = NULL;
  destroy_compress_ctx:
  	if (cops->destroy_compress_ctx)
  		cops->destroy_compress_ctx(cc);
  out:
  	trace_f2fs_compress_pages_end(cc->inode, cc->cluster_idx,
  							cc->clen, ret);
  	return ret;
  }
  
  static 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);
  	const struct f2fs_compress_ops *cops =
  			f2fs_cops[fi->i_compress_algorithm];
  	int ret;
  	int i;
  
  	trace_f2fs_decompress_pages_start(dic->inode, dic->cluster_idx,
  				dic->cluster_size, fi->i_compress_algorithm);
  
  	if (dic->failed) {
  		ret = -EIO;
  		goto out_end_io;
  	}
  
  	dic->tpages = page_array_alloc(dic->inode, dic->cluster_size);
  	if (!dic->tpages) {
  		ret = -ENOMEM;
  		goto out_end_io;
  	}
  
  	for (i = 0; i < dic->cluster_size; i++) {
  		if (dic->rpages[i]) {
  			dic->tpages[i] = dic->rpages[i];
  			continue;
  		}
  
  		dic->tpages[i] = f2fs_compress_alloc_page();
  		if (!dic->tpages[i]) {
  			ret = -ENOMEM;
  			goto out_end_io;
  		}
  	}
  
  	if (cops->init_decompress_ctx) {
  		ret = cops->init_decompress_ctx(dic);
  		if (ret)
  			goto out_end_io;
  	}
  
  	dic->rbuf = f2fs_vmap(dic->tpages, dic->cluster_size);
  	if (!dic->rbuf) {
  		ret = -ENOMEM;
  		goto out_destroy_decompress_ctx;
  	}
  
  	dic->cbuf = f2fs_vmap(dic->cpages, dic->nr_cpages);
  	if (!dic->cbuf) {
  		ret = -ENOMEM;
  		goto out_vunmap_rbuf;
  	}
  
  	dic->clen = le32_to_cpu(dic->cbuf->clen);
  	dic->rlen = PAGE_SIZE << dic->log_cluster_size;
  
  	if (dic->clen > PAGE_SIZE * dic->nr_cpages - COMPRESS_HEADER_SIZE) {
  		ret = -EFSCORRUPTED;
  		goto out_vunmap_cbuf;
  	}
  
  	ret = cops->decompress_pages(dic);
  
  	if (!ret && (fi->i_compress_flag & 1 << COMPRESS_CHKSUM)) {
  		u32 provided = le32_to_cpu(dic->cbuf->chksum);
  		u32 calculated = f2fs_crc32(sbi, dic->cbuf->cdata, dic->clen);
  
  		if (provided != calculated) {
  			if (!is_inode_flag_set(dic->inode, FI_COMPRESS_CORRUPT)) {
  				set_inode_flag(dic->inode, FI_COMPRESS_CORRUPT);
  				printk_ratelimited(
  					"%sF2FS-fs (%s): checksum invalid, nid = %lu, %x vs %x",
  					KERN_INFO, sbi->sb->s_id, dic->inode->i_ino,
  					provided, calculated);
  			}
  			set_sbi_flag(sbi, SBI_NEED_FSCK);
  		}
  	}
  
  out_vunmap_cbuf:
  	vm_unmap_ram(dic->cbuf, dic->nr_cpages);
  out_vunmap_rbuf:
  	vm_unmap_ram(dic->rbuf, dic->cluster_size);
  out_destroy_decompress_ctx:
  	if (cops->destroy_decompress_ctx)
  		cops->destroy_decompress_ctx(dic);
  out_end_io:
  	trace_f2fs_decompress_pages_end(dic->inode, dic->cluster_idx,
  							dic->clen, ret);
  	f2fs_decompress_end_io(dic, ret);
  }
  
  /*
   * This is called when a page of a compressed cluster has been read from disk
   * (or failed to be read from disk).  It checks whether this page was the last
   * 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)
  {
  	struct decompress_io_ctx *dic =
  			(struct decompress_io_ctx *)page_private(page);
  	struct f2fs_sb_info *sbi = F2FS_I_SB(dic->inode);
  
  	dec_page_count(sbi, F2FS_RD_DATA);
  
  	if (failed)
  		WRITE_ONCE(dic->failed, true);
  
  	if (atomic_dec_and_test(&dic->remaining_pages))
  		f2fs_decompress_cluster(dic);
  }
  
  static bool is_page_in_cluster(struct compress_ctx *cc, pgoff_t index)
  {
  	if (cc->cluster_idx == NULL_CLUSTER)
  		return true;
  	return cc->cluster_idx == cluster_idx(cc, index);
  }
  
  bool f2fs_cluster_is_empty(struct compress_ctx *cc)
  {
  	return cc->nr_rpages == 0;
  }
  
  static bool f2fs_cluster_is_full(struct compress_ctx *cc)
  {
  	return cc->cluster_size == cc->nr_rpages;
  }
  
  bool f2fs_cluster_can_merge_page(struct compress_ctx *cc, pgoff_t index)
  {
  	if (f2fs_cluster_is_empty(cc))
  		return true;
  	return is_page_in_cluster(cc, index);
  }
  
  static bool __cluster_may_compress(struct compress_ctx *cc)
  {
  	struct f2fs_sb_info *sbi = F2FS_I_SB(cc->inode);
  	loff_t i_size = i_size_read(cc->inode);
  	unsigned nr_pages = DIV_ROUND_UP(i_size, PAGE_SIZE);
  	int i;
  
  	for (i = 0; i < cc->cluster_size; i++) {
  		struct page *page = cc->rpages[i];
  
  		f2fs_bug_on(sbi, !page);
  
  		if (unlikely(f2fs_cp_error(sbi)))
  			return false;
  		if (unlikely(is_sbi_flag_set(sbi, SBI_POR_DOING)))
  			return false;
  
  		/* beyond EOF */
  		if (page->index >= nr_pages)
  			return false;
  	}
  	return true;
  }
  
  static int __f2fs_cluster_blocks(struct compress_ctx *cc, bool compr)
  {
  	struct dnode_of_data dn;
  	int ret;
  
  	set_new_dnode(&dn, cc->inode, NULL, NULL, 0);
  	ret = f2fs_get_dnode_of_data(&dn, start_idx_of_cluster(cc),
  							LOOKUP_NODE);
  	if (ret) {
  		if (ret == -ENOENT)
  			ret = 0;
  		goto fail;
  	}
  
  	if (dn.data_blkaddr == COMPRESS_ADDR) {
  		int i;
  
  		ret = 1;
  		for (i = 1; i < cc->cluster_size; i++) {
  			block_t blkaddr;
  
  			blkaddr = data_blkaddr(dn.inode,
  					dn.node_page, dn.ofs_in_node + i);
  			if (compr) {
  				if (__is_valid_data_blkaddr(blkaddr))
  					ret++;
  			} else {
  				if (blkaddr != NULL_ADDR)
  					ret++;
  			}
  		}
  	}
  fail:
  	f2fs_put_dnode(&dn);
  	return ret;
  }
  
  /* return # of compressed blocks in compressed cluster */
  static int f2fs_compressed_blocks(struct compress_ctx *cc)
  {
  	return __f2fs_cluster_blocks(cc, true);
  }
  
  /* return # of valid blocks in compressed cluster */
  static int f2fs_cluster_blocks(struct compress_ctx *cc)
  {
  	return __f2fs_cluster_blocks(cc, false);
  }
  
  int f2fs_is_compressed_cluster(struct inode *inode, pgoff_t index)
  {
  	struct compress_ctx cc = {
  		.inode = inode,
  		.log_cluster_size = F2FS_I(inode)->i_log_cluster_size,
  		.cluster_size = F2FS_I(inode)->i_cluster_size,
  		.cluster_idx = index >> F2FS_I(inode)->i_log_cluster_size,
  	};
  
  	return f2fs_cluster_blocks(&cc);
  }
  
  static bool cluster_may_compress(struct compress_ctx *cc)
  {
  	if (!f2fs_need_compress_data(cc->inode))
  		return false;
  	if (f2fs_is_atomic_file(cc->inode))
  		return false;
  	if (f2fs_is_mmap_file(cc->inode))
  		return false;
  	if (!f2fs_cluster_is_full(cc))
  		return false;
  	if (unlikely(f2fs_cp_error(F2FS_I_SB(cc->inode))))
  		return false;
  	return __cluster_may_compress(cc);
  }
  
  static void set_cluster_writeback(struct compress_ctx *cc)
  {
  	int i;
  
  	for (i = 0; i < cc->cluster_size; i++) {
  		if (cc->rpages[i])
  			set_page_writeback(cc->rpages[i]);
  	}
  }
  
  static void set_cluster_dirty(struct compress_ctx *cc)
  {
  	int i;
  
  	for (i = 0; i < cc->cluster_size; i++)
  		if (cc->rpages[i])
  			set_page_dirty(cc->rpages[i]);
  }
  
  static int prepare_compress_overwrite(struct compress_ctx *cc,
  		struct page **pagep, pgoff_t index, void **fsdata)
  {
  	struct f2fs_sb_info *sbi = F2FS_I_SB(cc->inode);
  	struct address_space *mapping = cc->inode->i_mapping;
  	struct page *page;
  	struct dnode_of_data dn;
  	sector_t last_block_in_bio;
  	unsigned fgp_flag = FGP_LOCK | FGP_WRITE | FGP_CREAT;
  	pgoff_t start_idx = start_idx_of_cluster(cc);
  	int i, ret;
  	bool prealloc;
  
  retry:
  	ret = f2fs_cluster_blocks(cc);
  	if (ret <= 0)
  		return ret;
  
  	/* compressed case */
  	prealloc = (ret < cc->cluster_size);
  
  	ret = f2fs_init_compress_ctx(cc);
  	if (ret)
  		return ret;
  
  	/* keep page reference to avoid page reclaim */
  	for (i = 0; i < cc->cluster_size; i++) {
  		page = f2fs_pagecache_get_page(mapping, start_idx + i,
  							fgp_flag, GFP_NOFS);
  		if (!page) {
  			ret = -ENOMEM;
  			goto unlock_pages;
  		}
  
  		if (PageUptodate(page))
  			f2fs_put_page(page, 1);
  		else
  			f2fs_compress_ctx_add_page(cc, page);
  	}
  
  	if (!f2fs_cluster_is_empty(cc)) {
  		struct bio *bio = NULL;
  
  		ret = f2fs_read_multi_pages(cc, &bio, cc->cluster_size,
  					&last_block_in_bio, false, true);
  		f2fs_put_rpages(cc);
  		f2fs_destroy_compress_ctx(cc, true);
  		if (ret)
  			goto out;
  		if (bio)
  			f2fs_submit_bio(sbi, bio, DATA);
  
  		ret = f2fs_init_compress_ctx(cc);
  		if (ret)
  			goto out;
  	}
  
  	for (i = 0; i < cc->cluster_size; i++) {
  		f2fs_bug_on(sbi, cc->rpages[i]);
  
  		page = find_lock_page(mapping, start_idx + i);
  		if (!page) {
  			/* page can be truncated */
  			goto release_and_retry;
  		}
  
  		f2fs_wait_on_page_writeback(page, DATA, true, true);
  		f2fs_compress_ctx_add_page(cc, page);
  
  		if (!PageUptodate(page)) {
  release_and_retry:
  			f2fs_put_rpages(cc);
  			f2fs_unlock_rpages(cc, i + 1);
  			f2fs_destroy_compress_ctx(cc, true);
  			goto retry;
  		}
  	}
  
  	if (prealloc) {
  		f2fs_do_map_lock(sbi, F2FS_GET_BLOCK_PRE_AIO, true);
  
  		set_new_dnode(&dn, cc->inode, NULL, NULL, 0);
  
  		for (i = cc->cluster_size - 1; i > 0; i--) {
  			ret = f2fs_get_block(&dn, start_idx + i);
  			if (ret) {
  				i = cc->cluster_size;
  				break;
  			}
  
  			if (dn.data_blkaddr != NEW_ADDR)
  				break;
  		}
  
  		f2fs_do_map_lock(sbi, F2FS_GET_BLOCK_PRE_AIO, false);
  	}
  
  	if (likely(!ret)) {
  		*fsdata = cc->rpages;
  		*pagep = cc->rpages[offset_in_cluster(cc, index)];
  		return cc->cluster_size;
  	}
  
  unlock_pages:
  	f2fs_put_rpages(cc);
  	f2fs_unlock_rpages(cc, i);
  	f2fs_destroy_compress_ctx(cc, true);
  out:
  	return ret;
  }
  
  int f2fs_prepare_compress_overwrite(struct inode *inode,
  		struct page **pagep, pgoff_t index, void **fsdata)
  {
  	struct compress_ctx cc = {
  		.inode = inode,
  		.log_cluster_size = F2FS_I(inode)->i_log_cluster_size,
  		.cluster_size = F2FS_I(inode)->i_cluster_size,
  		.cluster_idx = index >> F2FS_I(inode)->i_log_cluster_size,
  		.rpages = NULL,
  		.nr_rpages = 0,
  	};
  
  	return prepare_compress_overwrite(&cc, pagep, index, fsdata);
  }
  
  bool f2fs_compress_write_end(struct inode *inode, void *fsdata,
  					pgoff_t index, unsigned copied)
  
  {
  	struct compress_ctx cc = {
  		.inode = inode,
  		.log_cluster_size = F2FS_I(inode)->i_log_cluster_size,
  		.cluster_size = F2FS_I(inode)->i_cluster_size,
  		.rpages = fsdata,
  	};
  	bool first_index = (index == cc.rpages[0]->index);
  
  	if (copied)
  		set_cluster_dirty(&cc);
  
  	f2fs_put_rpages_wbc(&cc, NULL, false, 1);
  	f2fs_destroy_compress_ctx(&cc, false);
  
  	return first_index;
  }
  
  int f2fs_truncate_partial_cluster(struct inode *inode, u64 from, bool lock)
  {
  	void *fsdata = NULL;
  	struct page *pagep;
  	int log_cluster_size = F2FS_I(inode)->i_log_cluster_size;
  	pgoff_t start_idx = from >> (PAGE_SHIFT + log_cluster_size) <<
  							log_cluster_size;
  	int err;
  
  	err = f2fs_is_compressed_cluster(inode, start_idx);
  	if (err < 0)
  		return err;
  
  	/* truncate normal cluster */
  	if (!err)
  		return f2fs_do_truncate_blocks(inode, from, lock);
  
  	/* truncate compressed cluster */
  	err = f2fs_prepare_compress_overwrite(inode, &pagep,
  						start_idx, &fsdata);
  
  	/* should not be a normal cluster */
  	f2fs_bug_on(F2FS_I_SB(inode), err == 0);
  
  	if (err <= 0)
  		return err;
  
  	if (err > 0) {
  		struct page **rpages = fsdata;
  		int cluster_size = F2FS_I(inode)->i_cluster_size;
  		int i;
  
  		for (i = cluster_size - 1; i >= 0; i--) {
  			loff_t start = rpages[i]->index << PAGE_SHIFT;
  
  			if (from <= start) {
  				zero_user_segment(rpages[i], 0, PAGE_SIZE);
  			} else {
  				zero_user_segment(rpages[i], from - start,
  								PAGE_SIZE);
  				break;
  			}
  		}
  
  		f2fs_compress_write_end(inode, fsdata, start_idx, true);
  	}
  	return 0;
  }
  
  static int f2fs_write_compressed_pages(struct compress_ctx *cc,
  					int *submitted,
  					struct writeback_control *wbc,
  					enum iostat_type io_type)
  {
  	struct inode *inode = cc->inode;
  	struct f2fs_sb_info *sbi = F2FS_I_SB(inode);
  	struct f2fs_inode_info *fi = F2FS_I(inode);
  	struct f2fs_io_info fio = {
  		.sbi = sbi,
  		.ino = cc->inode->i_ino,
  		.type = DATA,
  		.op = REQ_OP_WRITE,
  		.op_flags = wbc_to_write_flags(wbc),
  		.old_blkaddr = NEW_ADDR,
  		.page = NULL,
  		.encrypted_page = NULL,
  		.compressed_page = NULL,
  		.submitted = false,
  		.io_type = io_type,
  		.io_wbc = wbc,
  		.encrypted = fscrypt_inode_uses_fs_layer_crypto(cc->inode),
  	};
  	struct dnode_of_data dn;
  	struct node_info ni;
  	struct compress_io_ctx *cic;
  	pgoff_t start_idx = start_idx_of_cluster(cc);
  	unsigned int last_index = cc->cluster_size - 1;
  	loff_t psize;
  	int i, err;
  
  	if (IS_NOQUOTA(inode)) {
  		/*
  		 * We need to wait for node_write to avoid block allocation during
  		 * checkpoint. This can only happen to quota writes which can cause
  		 * the below discard race condition.
  		 */
  		down_read(&sbi->node_write);
  	} else if (!f2fs_trylock_op(sbi)) {
  		goto out_free;
  	}
  
  	set_new_dnode(&dn, cc->inode, NULL, NULL, 0);
  
  	err = f2fs_get_dnode_of_data(&dn, start_idx, LOOKUP_NODE);
  	if (err)
  		goto out_unlock_op;
  
  	for (i = 0; i < cc->cluster_size; i++) {
  		if (data_blkaddr(dn.inode, dn.node_page,
  					dn.ofs_in_node + i) == NULL_ADDR)
  			goto out_put_dnode;
  	}
  
  	psize = (loff_t)(cc->rpages[last_index]->index + 1) << PAGE_SHIFT;
  
  	err = f2fs_get_node_info(fio.sbi, dn.nid, &ni);
  	if (err)
  		goto out_put_dnode;
  
  	fio.version = ni.version;
  
  	cic = kmem_cache_zalloc(cic_entry_slab, GFP_NOFS);
  	if (!cic)
  		goto out_put_dnode;
  
  	cic->magic = F2FS_COMPRESSED_PAGE_MAGIC;
  	cic->inode = inode;
  	atomic_set(&cic->pending_pages, cc->nr_cpages);
  	cic->rpages = page_array_alloc(cc->inode, cc->cluster_size);
  	if (!cic->rpages)
  		goto out_put_cic;
  
  	cic->nr_rpages = cc->cluster_size;
  
  	for (i = 0; i < cc->nr_cpages; i++) {
  		f2fs_set_compressed_page(cc->cpages[i], inode,
  					cc->rpages[i + 1]->index, cic);
  		fio.compressed_page = cc->cpages[i];
  
  		fio.old_blkaddr = data_blkaddr(dn.inode, dn.node_page,
  						dn.ofs_in_node + i + 1);
  
  		/* wait for GCed page writeback via META_MAPPING */
  		f2fs_wait_on_block_writeback(inode, fio.old_blkaddr);
  
  		if (fio.encrypted) {
  			fio.page = cc->rpages[i + 1];
  			err = f2fs_encrypt_one_page(&fio);
  			if (err)
  				goto out_destroy_crypt;
  			cc->cpages[i] = fio.encrypted_page;
  		}
  	}
  
  	set_cluster_writeback(cc);
  
  	for (i = 0; i < cc->cluster_size; i++)
  		cic->rpages[i] = cc->rpages[i];
  
  	for (i = 0; i < cc->cluster_size; i++, dn.ofs_in_node++) {
  		block_t blkaddr;
  
  		blkaddr = f2fs_data_blkaddr(&dn);
  		fio.page = cc->rpages[i];
  		fio.old_blkaddr = blkaddr;
  
  		/* cluster header */
  		if (i == 0) {
  			if (blkaddr == COMPRESS_ADDR)
  				fio.compr_blocks++;
  			if (__is_valid_data_blkaddr(blkaddr))
  				f2fs_invalidate_blocks(sbi, blkaddr);
  			f2fs_update_data_blkaddr(&dn, COMPRESS_ADDR);
  			goto unlock_continue;
  		}
  
  		if (fio.compr_blocks && __is_valid_data_blkaddr(blkaddr))
  			fio.compr_blocks++;
  
  		if (i > cc->nr_cpages) {
  			if (__is_valid_data_blkaddr(blkaddr)) {
  				f2fs_invalidate_blocks(sbi, blkaddr);
  				f2fs_update_data_blkaddr(&dn, NEW_ADDR);
  			}
  			goto unlock_continue;
  		}
  
  		f2fs_bug_on(fio.sbi, blkaddr == NULL_ADDR);
  
  		if (fio.encrypted)
  			fio.encrypted_page = cc->cpages[i - 1];
  		else
  			fio.compressed_page = cc->cpages[i - 1];
  
  		cc->cpages[i - 1] = NULL;
  		f2fs_outplace_write_data(&dn, &fio);
  		(*submitted)++;
  unlock_continue:
  		inode_dec_dirty_pages(cc->inode);
  		unlock_page(fio.page);
  	}
  
  	if (fio.compr_blocks)
  		f2fs_i_compr_blocks_update(inode, fio.compr_blocks - 1, false);
  	f2fs_i_compr_blocks_update(inode, cc->nr_cpages, true);
  
  	set_inode_flag(cc->inode, FI_APPEND_WRITE);
  	if (cc->cluster_idx == 0)
  		set_inode_flag(inode, FI_FIRST_BLOCK_WRITTEN);
  
  	f2fs_put_dnode(&dn);
  	if (IS_NOQUOTA(inode))
  		up_read(&sbi->node_write);
  	else
  		f2fs_unlock_op(sbi);
  
  	spin_lock(&fi->i_size_lock);
  	if (fi->last_disk_size < psize)
  		fi->last_disk_size = psize;
  	spin_unlock(&fi->i_size_lock);
  
  	f2fs_put_rpages(cc);
  	page_array_free(cc->inode, cc->cpages, cc->nr_cpages);
  	cc->cpages = NULL;
  	f2fs_destroy_compress_ctx(cc, false);
  	return 0;
  
  out_destroy_crypt:
  	page_array_free(cc->inode, cic->rpages, cc->cluster_size);
  
  	for (--i; i >= 0; i--)
  		fscrypt_finalize_bounce_page(&cc->cpages[i]);
  	for (i = 0; i < cc->nr_cpages; i++) {
  		if (!cc->cpages[i])
  			continue;
  		f2fs_compress_free_page(cc->cpages[i]);
  		cc->cpages[i] = NULL;
  	}
  out_put_cic:
  	kmem_cache_free(cic_entry_slab, cic);
  out_put_dnode:
  	f2fs_put_dnode(&dn);
  out_unlock_op:
  	if (IS_NOQUOTA(inode))
  		up_read(&sbi->node_write);
  	else
  		f2fs_unlock_op(sbi);
  out_free:
  	page_array_free(cc->inode, cc->cpages, cc->nr_cpages);
  	cc->cpages = NULL;
  	return -EAGAIN;
  }
  
  void f2fs_compress_write_end_io(struct bio *bio, struct page *page)
  {
  	struct f2fs_sb_info *sbi = bio->bi_private;
  	struct compress_io_ctx *cic =
  			(struct compress_io_ctx *)page_private(page);
  	int i;
  
  	if (unlikely(bio->bi_status))
  		mapping_set_error(cic->inode->i_mapping, -EIO);
  
  	f2fs_compress_free_page(page);
  
  	dec_page_count(sbi, F2FS_WB_DATA);
  
  	if (atomic_dec_return(&cic->pending_pages))
  		return;
  
  	for (i = 0; i < cic->nr_rpages; i++) {
  		WARN_ON(!cic->rpages[i]);
  		clear_cold_data(cic->rpages[i]);
  		end_page_writeback(cic->rpages[i]);
  	}
  
  	page_array_free(cic->inode, cic->rpages, cic->nr_rpages);
  	kmem_cache_free(cic_entry_slab, cic);
  }
  
  static int f2fs_write_raw_pages(struct compress_ctx *cc,
  					int *submitted,
  					struct writeback_control *wbc,
  					enum iostat_type io_type)
  {
  	struct address_space *mapping = cc->inode->i_mapping;
  	int _submitted, compr_blocks, ret;
  	int i = -1, err = 0;
  
  	compr_blocks = f2fs_compressed_blocks(cc);
  	if (compr_blocks < 0) {
  		err = compr_blocks;
  		goto out_err;
  	}
  
  	for (i = 0; i < cc->cluster_size; i++) {
  		if (!cc->rpages[i])
  			continue;
  retry_write:
  		if (cc->rpages[i]->mapping != mapping) {
  			unlock_page(cc->rpages[i]);
  			continue;
  		}
  
  		BUG_ON(!PageLocked(cc->rpages[i]));
  
  		ret = f2fs_write_single_data_page(cc->rpages[i], &_submitted,
  						NULL, NULL, wbc, io_type,
  						compr_blocks, false);
  		if (ret) {
  			if (ret == AOP_WRITEPAGE_ACTIVATE) {
  				unlock_page(cc->rpages[i]);
  				ret = 0;
  			} else if (ret == -EAGAIN) {
  				/*
  				 * for quota file, just redirty left pages to
  				 * avoid deadlock caused by cluster update race
  				 * from foreground operation.
  				 */
  				if (IS_NOQUOTA(cc->inode)) {
  					err = 0;
  					goto out_err;
  				}
  				ret = 0;
  				cond_resched();
  				congestion_wait(BLK_RW_ASYNC,
  						DEFAULT_IO_TIMEOUT);
  				lock_page(cc->rpages[i]);
  
  				if (!PageDirty(cc->rpages[i])) {
  					unlock_page(cc->rpages[i]);
  					continue;
  				}
  
  				clear_page_dirty_for_io(cc->rpages[i]);
  				goto retry_write;
  			}
  			err = ret;
  			goto out_err;
  		}
  
  		*submitted += _submitted;
  	}
  
  	f2fs_balance_fs(F2FS_M_SB(mapping), true);
  
  	return 0;
  out_err:
  	for (++i; i < cc->cluster_size; i++) {
  		if (!cc->rpages[i])
  			continue;
  		redirty_page_for_writepage(wbc, cc->rpages[i]);
  		unlock_page(cc->rpages[i]);
  	}
  	return err;
  }
  
  int f2fs_write_multi_pages(struct compress_ctx *cc,
  					int *submitted,
  					struct writeback_control *wbc,
  					enum iostat_type io_type)
  {
  	int err;
  
  	*submitted = 0;
  	if (cluster_may_compress(cc)) {
  		err = f2fs_compress_pages(cc);
  		if (err == -EAGAIN) {
  			goto write;
  		} else if (err) {
  			f2fs_put_rpages_wbc(cc, wbc, true, 1);
  			goto destroy_out;
  		}
  
  		err = f2fs_write_compressed_pages(cc, submitted,
  							wbc, io_type);
  		if (!err)
  			return 0;
  		f2fs_bug_on(F2FS_I_SB(cc->inode), err != -EAGAIN);
  	}
  write:
  	f2fs_bug_on(F2FS_I_SB(cc->inode), *submitted);
  
  	err = f2fs_write_raw_pages(cc, submitted, wbc, io_type);
  	f2fs_put_rpages_wbc(cc, wbc, false, 0);
  destroy_out:
  	f2fs_destroy_compress_ctx(cc, false);
  	return err;
  }
  
  static void f2fs_free_dic(struct decompress_io_ctx *dic);
  
  struct decompress_io_ctx *f2fs_alloc_dic(struct compress_ctx *cc)
  {
  	struct decompress_io_ctx *dic;
  	pgoff_t start_idx = start_idx_of_cluster(cc);
  	int i;
  
  	dic = kmem_cache_zalloc(dic_entry_slab, GFP_NOFS);
  	if (!dic)
  		return ERR_PTR(-ENOMEM);
  
  	dic->rpages = page_array_alloc(cc->inode, cc->cluster_size);
  	if (!dic->rpages) {
  		kmem_cache_free(dic_entry_slab, dic);
  		return ERR_PTR(-ENOMEM);
  	}
  
  	dic->magic = F2FS_COMPRESSED_PAGE_MAGIC;
  	dic->inode = cc->inode;
  	atomic_set(&dic->remaining_pages, cc->nr_cpages);
  	dic->cluster_idx = cc->cluster_idx;
  	dic->cluster_size = cc->cluster_size;
  	dic->log_cluster_size = cc->log_cluster_size;
  	dic->nr_cpages = cc->nr_cpages;
  	refcount_set(&dic->refcnt, 1);
  	dic->failed = false;
  	dic->need_verity = f2fs_need_verity(cc->inode, start_idx);
  
  	for (i = 0; i < dic->cluster_size; i++)
  		dic->rpages[i] = cc->rpages[i];
  	dic->nr_rpages = cc->cluster_size;
  
  	dic->cpages = page_array_alloc(dic->inode, dic->nr_cpages);
  	if (!dic->cpages)
  		goto out_free;
  
  	for (i = 0; i < dic->nr_cpages; i++) {
  		struct page *page;
  
  		page = f2fs_compress_alloc_page();
  		if (!page)
  			goto out_free;
  
  		f2fs_set_compressed_page(page, cc->inode,
  					start_idx + i + 1, dic);
  		dic->cpages[i] = page;
  	}
  
  	return dic;
  
  out_free:
  	f2fs_free_dic(dic);
  	return ERR_PTR(-ENOMEM);
  }
  
  static void f2fs_free_dic(struct decompress_io_ctx *dic)
  {
  	int i;
  
  	if (dic->tpages) {
  		for (i = 0; i < dic->cluster_size; i++) {
  			if (dic->rpages[i])
  				continue;
  			if (!dic->tpages[i])
  				continue;
  			f2fs_compress_free_page(dic->tpages[i]);
  		}
  		page_array_free(dic->inode, dic->tpages, dic->cluster_size);
  	}
  
  	if (dic->cpages) {
  		for (i = 0; i < dic->nr_cpages; i++) {
  			if (!dic->cpages[i])
  				continue;
  			f2fs_compress_free_page(dic->cpages[i]);
  		}
  		page_array_free(dic->inode, dic->cpages, dic->nr_cpages);
  	}
  
  	page_array_free(dic->inode, dic->rpages, dic->nr_rpages);
  	kmem_cache_free(dic_entry_slab, dic);
  }
  
  static void f2fs_put_dic(struct decompress_io_ctx *dic)
  {
  	if (refcount_dec_and_test(&dic->refcnt))
  		f2fs_free_dic(dic);
  }
  
  /*
   * Update and unlock the cluster's pagecache pages, and release the reference to
   * the decompress_io_ctx that was being held for I/O completion.
   */
  static void __f2fs_decompress_end_io(struct decompress_io_ctx *dic, bool failed)
  {
  	int i;
  
  	for (i = 0; i < dic->cluster_size; i++) {
  		struct page *rpage = dic->rpages[i];
  
  		if (!rpage)
  			continue;
  
  		/* PG_error was set if verity failed. */
  		if (failed || PageError(rpage)) {
  			ClearPageUptodate(rpage);
  			/* will re-read again later */
  			ClearPageError(rpage);
  		} else {
  			SetPageUptodate(rpage);
  		}
  		unlock_page(rpage);
  	}
  
  	f2fs_put_dic(dic);
  }
  
  static void f2fs_verify_cluster(struct work_struct *work)
  {
  	struct decompress_io_ctx *dic =
  		container_of(work, struct decompress_io_ctx, verity_work);
  	int i;
  
  	/* Verify the cluster's decompressed pages with fs-verity. */
  	for (i = 0; i < dic->cluster_size; i++) {
  		struct page *rpage = dic->rpages[i];
  
  		if (rpage && !fsverity_verify_page(rpage))
  			SetPageError(rpage);
  	}
  
  	__f2fs_decompress_end_io(dic, false);
  }
  
  /*
   * This is called when a compressed cluster has been decompressed
   * (or failed to be read and/or decompressed).
   */
  void f2fs_decompress_end_io(struct decompress_io_ctx *dic, bool failed)
  {
  	if (!failed && dic->need_verity) {
  		/*
  		 * Note that to avoid deadlocks, the verity work can't be done
  		 * on the decompression workqueue.  This is because verifying
  		 * the data pages can involve reading metadata pages from the
  		 * file, and these metadata pages may be compressed.
  		 */
  		INIT_WORK(&dic->verity_work, f2fs_verify_cluster);
  		fsverity_enqueue_verify_work(&dic->verity_work);
  	} else {
  		__f2fs_decompress_end_io(dic, failed);
  	}
  }
  
  /*
   * Put a reference to a compressed page's decompress_io_ctx.
   *
   * This is called when the page is no longer needed and can be freed.
   */
  void f2fs_put_page_dic(struct page *page)
  {
  	struct decompress_io_ctx *dic =
  			(struct decompress_io_ctx *)page_private(page);
  
  	f2fs_put_dic(dic);
  }
  
  int f2fs_init_page_array_cache(struct f2fs_sb_info *sbi)
  {
  	dev_t dev = sbi->sb->s_bdev->bd_dev;
  	char slab_name[32];
  
  	sprintf(slab_name, "f2fs_page_array_entry-%u:%u", MAJOR(dev), MINOR(dev));
  
  	sbi->page_array_slab_size = sizeof(struct page *) <<
  					F2FS_OPTION(sbi).compress_log_size;
  
  	sbi->page_array_slab = f2fs_kmem_cache_create(slab_name,
  					sbi->page_array_slab_size);
  	if (!sbi->page_array_slab)
  		return -ENOMEM;
  	return 0;
  }
  
  void f2fs_destroy_page_array_cache(struct f2fs_sb_info *sbi)
  {
  	kmem_cache_destroy(sbi->page_array_slab);
  }
  
  static int __init f2fs_init_cic_cache(void)
  {
  	cic_entry_slab = f2fs_kmem_cache_create("f2fs_cic_entry",
  					sizeof(struct compress_io_ctx));
  	if (!cic_entry_slab)
  		return -ENOMEM;
  	return 0;
  }
  
  static void f2fs_destroy_cic_cache(void)
  {
  	kmem_cache_destroy(cic_entry_slab);
  }
  
  static int __init f2fs_init_dic_cache(void)
  {
  	dic_entry_slab = f2fs_kmem_cache_create("f2fs_dic_entry",
  					sizeof(struct decompress_io_ctx));
  	if (!dic_entry_slab)
  		return -ENOMEM;
  	return 0;
  }
  
  static void f2fs_destroy_dic_cache(void)
  {
  	kmem_cache_destroy(dic_entry_slab);
  }
  
  int __init f2fs_init_compress_cache(void)
  {
  	int err;
  
  	err = f2fs_init_cic_cache();
  	if (err)
  		goto out;
  	err = f2fs_init_dic_cache();
  	if (err)
  		goto free_cic;
  	return 0;
  free_cic:
  	f2fs_destroy_cic_cache();
  out:
  	return -ENOMEM;
  }
  
  void f2fs_destroy_compress_cache(void)
  {
  	f2fs_destroy_dic_cache();
  	f2fs_destroy_cic_cache();
  }
  