diff --git a/fs/erofs/Kconfig b/fs/erofs/Kconfig
index f259d92c9720..56a99ba8ce22 100644
--- a/fs/erofs/Kconfig
+++ b/fs/erofs/Kconfig
@@ -99,6 +99,21 @@ config EROFS_FS_ZIP_LZMA
 
 	  If unsure, say N.
 
+config EROFS_FS_ZIP_DEFLATE
+	bool "EROFS DEFLATE compressed data support"
+	depends on EROFS_FS_ZIP
+	select ZLIB_INFLATE
+	help
+	  Saying Y here includes support for reading EROFS file systems
+	  containing DEFLATE compressed data.  It gives better compression
+	  ratios than the default LZ4 format, while it costs more CPU
+	  overhead.
+
+	  DEFLATE support is an experimental feature for now and so most
+	  file systems will be readable without selecting this option.
+
+	  If unsure, say N.
+
 config EROFS_FS_ONDEMAND
 	bool "EROFS fscache-based on-demand read support"
 	depends on CACHEFILES_ONDEMAND && (EROFS_FS=m && FSCACHE || EROFS_FS=y && FSCACHE=y)
diff --git a/fs/erofs/Makefile b/fs/erofs/Makefile
index a3a98fc3e481..994d0b9deddf 100644
--- a/fs/erofs/Makefile
+++ b/fs/erofs/Makefile
@@ -5,4 +5,5 @@ erofs-objs := super.o inode.o data.o namei.o dir.o utils.o sysfs.o
 erofs-$(CONFIG_EROFS_FS_XATTR) += xattr.o
 erofs-$(CONFIG_EROFS_FS_ZIP) += decompressor.o zmap.o zdata.o pcpubuf.o
 erofs-$(CONFIG_EROFS_FS_ZIP_LZMA) += decompressor_lzma.o
+erofs-$(CONFIG_EROFS_FS_ZIP_DEFLATE) += decompressor_deflate.o
 erofs-$(CONFIG_EROFS_FS_ONDEMAND) += fscache.o
diff --git a/fs/erofs/compress.h b/fs/erofs/compress.h
index b1b846504027..349c3316ae6b 100644
--- a/fs/erofs/compress.h
+++ b/fs/erofs/compress.h
@@ -94,4 +94,6 @@ extern const struct z_erofs_decompressor erofs_decompressors[];
 /* prototypes for specific algorithms */
 int z_erofs_lzma_decompress(struct z_erofs_decompress_req *rq,
 			    struct page **pagepool);
+int z_erofs_deflate_decompress(struct z_erofs_decompress_req *rq,
+			       struct page **pagepool);
 #endif
diff --git a/fs/erofs/decompressor.c b/fs/erofs/decompressor.c
index cfad1eac7fd9..332ec5f74002 100644
--- a/fs/erofs/decompressor.c
+++ b/fs/erofs/decompressor.c
@@ -379,4 +379,10 @@ const struct z_erofs_decompressor erofs_decompressors[] = {
 		.name = "lzma"
 	},
 #endif
+#ifdef CONFIG_EROFS_FS_ZIP_DEFLATE
+	[Z_EROFS_COMPRESSION_DEFLATE] = {
+		.decompress = z_erofs_deflate_decompress,
+		.name = "deflate"
+	},
+#endif
 };
diff --git a/fs/erofs/decompressor_deflate.c b/fs/erofs/decompressor_deflate.c
new file mode 100644
index 000000000000..3f2495821df0
--- /dev/null
+++ b/fs/erofs/decompressor_deflate.c
@@ -0,0 +1,252 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+#include <linux/module.h>
+#include <linux/zlib.h>
+#include "compress.h"
+
+struct z_erofs_deflate {
+	struct z_erofs_deflate *next;
+	struct z_stream_s z;
+	u8 bounce[PAGE_SIZE];
+};
+
+static DEFINE_SPINLOCK(z_erofs_deflate_lock);
+static unsigned int z_erofs_deflate_nstrms, z_erofs_deflate_avail_strms;
+static struct z_erofs_deflate *z_erofs_deflate_head;
+static DECLARE_WAIT_QUEUE_HEAD(z_erofs_deflate_wq);
+
+module_param_named(deflate_streams, z_erofs_deflate_nstrms, uint, 0444);
+
+void z_erofs_deflate_exit(void)
+{
+	/* there should be no running fs instance */
+	while (z_erofs_deflate_avail_strms) {
+		struct z_erofs_deflate *strm;
+
+		spin_lock(&z_erofs_deflate_lock);
+		strm = z_erofs_deflate_head;
+		if (!strm) {
+			spin_unlock(&z_erofs_deflate_lock);
+			DBG_BUGON(1);
+			return;
+		}
+		z_erofs_deflate_head = NULL;
+		spin_unlock(&z_erofs_deflate_lock);
+
+		while (strm) {
+			struct z_erofs_deflate *n = strm->next;
+
+			vfree(strm->z.workspace);
+			kfree(strm);
+			--z_erofs_deflate_avail_strms;
+			strm = n;
+		}
+	}
+}
+
+int __init z_erofs_deflate_init(void)
+{
+	/* by default, use # of possible CPUs instead */
+	if (!z_erofs_deflate_nstrms)
+		z_erofs_deflate_nstrms = num_possible_cpus();
+
+	for (; z_erofs_deflate_avail_strms < z_erofs_deflate_nstrms;
+	     ++z_erofs_deflate_avail_strms) {
+		struct z_erofs_deflate *strm;
+
+		strm = kzalloc(sizeof(*strm), GFP_KERNEL);
+		if (!strm)
+			goto out_failed;
+
+		/* XXX: in-kernel zlib cannot shrink windowbits currently */
+		strm->z.workspace = vmalloc(zlib_inflate_workspacesize());
+		if (!strm->z.workspace) {
+			kfree(strm);
+			goto out_failed;
+		}
+
+		spin_lock(&z_erofs_deflate_lock);
+		strm->next = z_erofs_deflate_head;
+		z_erofs_deflate_head = strm;
+		spin_unlock(&z_erofs_deflate_lock);
+	}
+	return 0;
+
+out_failed:
+	pr_err("failed to allocate zlib workspace\n");
+	z_erofs_deflate_exit();
+	return -ENOMEM;
+}
+
+int z_erofs_load_deflate_config(struct super_block *sb,
+				struct erofs_super_block *dsb,
+				struct z_erofs_deflate_cfgs *dfl, int size)
+{
+	if (!dfl || size < sizeof(struct z_erofs_deflate_cfgs)) {
+		erofs_err(sb, "invalid deflate cfgs, size=%u", size);
+		return -EINVAL;
+	}
+
+	if (dfl->windowbits > MAX_WBITS) {
+		erofs_err(sb, "unsupported windowbits %u", dfl->windowbits);
+		return -EOPNOTSUPP;
+	}
+
+	erofs_info(sb, "EXPERIMENTAL DEFLATE feature in use. Use at your own risk!");
+	return 0;
+}
+
+int z_erofs_deflate_decompress(struct z_erofs_decompress_req *rq,
+			       struct page **pagepool)
+{
+	static u8 skipped[PAGE_SIZE];
+	const unsigned int nrpages_out =
+		PAGE_ALIGN(rq->pageofs_out + rq->outputsize) >> PAGE_SHIFT;
+	const unsigned int nrpages_in =
+		PAGE_ALIGN(rq->inputsize) >> PAGE_SHIFT;
+	struct super_block *sb = rq->sb;
+	unsigned int insz, outsz, pofs;
+	struct z_erofs_deflate *strm;
+	u8 *kin, *kout = NULL;
+	bool bounced = false;
+	int no = -1, ni = 0, j = 0, zerr, err;
+
+	/* 1. get the exact DEFLATE compressed size */
+	kin = kmap_local_page(*rq->in);
+	err = z_erofs_fixup_insize(rq, kin + rq->pageofs_in,
+			min_t(unsigned int, rq->inputsize,
+			      sb->s_blocksize - rq->pageofs_in));
+	if (err) {
+		kunmap_local(kin);
+		return err;
+	}
+
+	/* 2. get an available DEFLATE context */
+again:
+	spin_lock(&z_erofs_deflate_lock);
+	strm = z_erofs_deflate_head;
+	if (!strm) {
+		spin_unlock(&z_erofs_deflate_lock);
+		wait_event(z_erofs_deflate_wq, READ_ONCE(z_erofs_deflate_head));
+		goto again;
+	}
+	z_erofs_deflate_head = strm->next;
+	spin_unlock(&z_erofs_deflate_lock);
+
+	/* 3. multi-call decompress */
+	insz = rq->inputsize;
+	outsz = rq->outputsize;
+	zerr = zlib_inflateInit2(&strm->z, -MAX_WBITS);
+	if (zerr != Z_OK) {
+		err = -EIO;
+		goto failed_zinit;
+	}
+
+	pofs = rq->pageofs_out;
+	strm->z.avail_in = min_t(u32, insz, PAGE_SIZE - rq->pageofs_in);
+	insz -= strm->z.avail_in;
+	strm->z.next_in = kin + rq->pageofs_in;
+	strm->z.avail_out = 0;
+
+	while (1) {
+		if (!strm->z.avail_out) {
+			if (++no >= nrpages_out || !outsz) {
+				erofs_err(sb, "insufficient space for decompressed data");
+				err = -EFSCORRUPTED;
+				break;
+			}
+
+			if (kout)
+				kunmap_local(kout);
+			strm->z.avail_out = min_t(u32, outsz, PAGE_SIZE - pofs);
+			outsz -= strm->z.avail_out;
+			if (rq->out[no] && rq->fillgaps) /* deduped data */
+				rq->out[no] = erofs_allocpage(pagepool,
+						GFP_KERNEL | __GFP_NOFAIL);
+			if (rq->out[no]) {
+				kout = kmap_local_page(rq->out[no]) + pofs;
+				strm->z.next_out = kout;
+			} else {
+				kout = NULL;
+				strm->z.next_out = skipped;
+			}
+			pofs = 0;
+		}
+
+		if (!strm->z.avail_in && insz) {
+			if (++ni >= nrpages_in) {
+				erofs_err(sb, "compressed data was invalid");
+				err = -EFSCORRUPTED;
+				break;
+			}
+
+			if (kout) { /* unlike kmap(), take care of the orders */
+				j = strm->z.next_out - kout;
+				kunmap_local(kout);
+			}
+			kunmap_local(kin);
+			strm->z.avail_in = min_t(u32, insz, PAGE_SIZE);
+			insz -= strm->z.avail_in;
+			kin = kmap_local_page(rq->in[ni]);
+			strm->z.next_in = kin;
+			bounced = false;
+			if (kout) {
+				kout = kmap_local_page(rq->out[no]);
+				strm->z.next_out = kout + j;
+			}
+		}
+
+		/*
+		 * Handle overlapping: Use bounced buffer if the compressed
+		 * data is under processing; Or use short-lived pages from the
+		 * on-stack pagepool where pages share among the same request
+		 * and not _all_ inplace I/O pages are needed to be doubled.
+		 */
+		if (!bounced && rq->out[no] == rq->in[ni]) {
+			memcpy(strm->bounce, strm->z.next_in, strm->z.avail_in);
+			strm->z.next_in = strm->bounce;
+			bounced = true;
+		}
+
+		for (j = ni + 1; j < nrpages_in; ++j) {
+			struct page *tmppage;
+
+			if (rq->out[no] != rq->in[j])
+				continue;
+
+			DBG_BUGON(erofs_page_is_managed(EROFS_SB(sb),
+							rq->in[j]));
+			tmppage = erofs_allocpage(pagepool,
+						  GFP_KERNEL | __GFP_NOFAIL);
+			set_page_private(tmppage, Z_EROFS_SHORTLIVED_PAGE);
+			copy_highpage(tmppage, rq->in[j]);
+			rq->in[j] = tmppage;
+		}
+
+		zerr = zlib_inflate(&strm->z, Z_SYNC_FLUSH);
+		if (zerr != Z_OK || !outsz) {
+			if (zerr == Z_OK && rq->partial_decoding)
+				break;
+			if (zerr == Z_STREAM_END && !outsz)
+				break;
+			erofs_err(sb, "failed to decompress %d in[%u] out[%u]",
+				  zerr, rq->inputsize, rq->outputsize);
+			err = -EFSCORRUPTED;
+			break;
+		}
+	}
+
+	if (zlib_inflateEnd(&strm->z) != Z_OK && !err)
+		err = -EIO;
+	if (kout)
+		kunmap_local(kout);
+failed_zinit:
+	if (kin)
+		kunmap_local(kin);
+	/* 4. push back DEFLATE stream context to the global list */
+	spin_lock(&z_erofs_deflate_lock);
+	strm->next = z_erofs_deflate_head;
+	z_erofs_deflate_head = strm;
+	spin_unlock(&z_erofs_deflate_lock);
+	wake_up(&z_erofs_deflate_wq);
+	return err;
+}
diff --git a/fs/erofs/erofs_fs.h b/fs/erofs/erofs_fs.h
index 2c7b16e340fe..364f51171c13 100644
--- a/fs/erofs/erofs_fs.h
+++ b/fs/erofs/erofs_fs.h
@@ -289,6 +289,7 @@ struct erofs_dirent {
 enum {
 	Z_EROFS_COMPRESSION_LZ4		= 0,
 	Z_EROFS_COMPRESSION_LZMA	= 1,
+	Z_EROFS_COMPRESSION_DEFLATE	= 2,
 	Z_EROFS_COMPRESSION_MAX
 };
 #define Z_EROFS_ALL_COMPR_ALGS		((1 << Z_EROFS_COMPRESSION_MAX) - 1)
@@ -309,6 +310,12 @@ struct z_erofs_lzma_cfgs {
 
 #define Z_EROFS_LZMA_MAX_DICT_SIZE	(8 * Z_EROFS_PCLUSTER_MAX_SIZE)
 
+/* 6 bytes (+ length field = 8 bytes) */
+struct z_erofs_deflate_cfgs {
+	u8 windowbits;			/* 8..15 for DEFLATE */
+	u8 reserved[5];
+} __packed;
+
 /*
  * bit 0 : COMPACTED_2B indexes (0 - off; 1 - on)
  *  e.g. for 4k logical cluster size,      4B        if compacted 2B is off;
diff --git a/fs/erofs/internal.h b/fs/erofs/internal.h
index 36e32fa542f0..fb45855cfd5d 100644
--- a/fs/erofs/internal.h
+++ b/fs/erofs/internal.h
@@ -519,6 +519,26 @@ static inline int z_erofs_load_lzma_config(struct super_block *sb,
 }
 #endif	/* !CONFIG_EROFS_FS_ZIP_LZMA */
 
+#ifdef CONFIG_EROFS_FS_ZIP_DEFLATE
+int __init z_erofs_deflate_init(void);
+void z_erofs_deflate_exit(void);
+int z_erofs_load_deflate_config(struct super_block *sb,
+				struct erofs_super_block *dsb,
+				struct z_erofs_deflate_cfgs *dfl, int size);
+#else
+static inline int z_erofs_deflate_init(void) { return 0; }
+static inline int z_erofs_deflate_exit(void) { return 0; }
+static inline int z_erofs_load_deflate_config(struct super_block *sb,
+			struct erofs_super_block *dsb,
+			struct z_erofs_deflate_cfgs *dfl, int size) {
+	if (dfl) {
+		erofs_err(sb, "deflate algorithm isn't enabled");
+		return -EINVAL;
+	}
+	return 0;
+}
+#endif	/* !CONFIG_EROFS_FS_ZIP_DEFLATE */
+
 #ifdef CONFIG_EROFS_FS_ONDEMAND
 int erofs_fscache_register_fs(struct super_block *sb);
 void erofs_fscache_unregister_fs(struct super_block *sb);
diff --git a/fs/erofs/super.c b/fs/erofs/super.c
index 9d6a3c6158bd..832f9fdef712 100644
--- a/fs/erofs/super.c
+++ b/fs/erofs/super.c
@@ -201,6 +201,9 @@ static int erofs_load_compr_cfgs(struct super_block *sb,
 		case Z_EROFS_COMPRESSION_LZMA:
 			ret = z_erofs_load_lzma_config(sb, dsb, data, size);
 			break;
+		case Z_EROFS_COMPRESSION_DEFLATE:
+			ret = z_erofs_load_deflate_config(sb, dsb, data, size);
+			break;
 		default:
 			DBG_BUGON(1);
 			ret = -EFAULT;
@@ -966,6 +969,10 @@ static int __init erofs_module_init(void)
 	if (err)
 		goto lzma_err;
 
+	err = z_erofs_deflate_init();
+	if (err)
+		goto deflate_err;
+
 	erofs_pcpubuf_init();
 	err = z_erofs_init_zip_subsystem();
 	if (err)
@@ -986,6 +993,8 @@ static int __init erofs_module_init(void)
 sysfs_err:
 	z_erofs_exit_zip_subsystem();
 zip_err:
+	z_erofs_deflate_exit();
+deflate_err:
 	z_erofs_lzma_exit();
 lzma_err:
 	erofs_exit_shrinker();
@@ -1003,6 +1012,7 @@ static void __exit erofs_module_exit(void)
 
 	erofs_exit_sysfs();
 	z_erofs_exit_zip_subsystem();
+	z_erofs_deflate_exit();
 	z_erofs_lzma_exit();
 	erofs_exit_shrinker();
 	kmem_cache_destroy(erofs_inode_cachep);
diff --git a/fs/erofs/zmap.c b/fs/erofs/zmap.c
index 1909ddafd9c7..7b55111fd533 100644
--- a/fs/erofs/zmap.c
+++ b/fs/erofs/zmap.c
@@ -561,8 +561,9 @@ static int z_erofs_do_map_blocks(struct inode *inode,
 
 	if ((flags & EROFS_GET_BLOCKS_FIEMAP) ||
 	    ((flags & EROFS_GET_BLOCKS_READMORE) &&
-	     map->m_algorithmformat == Z_EROFS_COMPRESSION_LZMA &&
-	     map->m_llen >= i_blocksize(inode))) {
+	     (map->m_algorithmformat == Z_EROFS_COMPRESSION_LZMA ||
+	      map->m_algorithmformat == Z_EROFS_COMPRESSION_DEFLATE) &&
+	      map->m_llen >= i_blocksize(inode))) {
 		err = z_erofs_get_extent_decompressedlen(&m);
 		if (!err)
 			map->m_flags |= EROFS_MAP_FULL_MAPPED;
