1 files changed, 235 insertions, 0 deletions
diff --git a/fs/erofs/decompressor_lzma.c b/fs/erofs/decompressor_lzma.c
new file mode 100644
index 000000000000..b4ea6978faae
--- /dev/null
+++ b/fs/erofs/decompressor_lzma.c
@@ -0,0 +1,235 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+#include <linux/xz.h>
+#include "compress.h"
+
+struct z_erofs_lzma {
+	struct z_erofs_lzma *next;
+	struct xz_dec_microlzma *state;
+	u8 bounce[PAGE_SIZE];
+};
+
+/* considering the LZMA performance, no need to use a lockless list for now */
+static DEFINE_SPINLOCK(z_erofs_lzma_lock);
+static unsigned int z_erofs_lzma_max_dictsize;
+static unsigned int z_erofs_lzma_nstrms, z_erofs_lzma_avail_strms;
+static struct z_erofs_lzma *z_erofs_lzma_head;
+static DECLARE_WAIT_QUEUE_HEAD(z_erofs_lzma_wq);
+
+module_param_named(lzma_streams, z_erofs_lzma_nstrms, uint, 0444);
+
+static void z_erofs_lzma_exit(void)
+{
+	/* there should be no running fs instance */
+	while (z_erofs_lzma_avail_strms) {
+		struct z_erofs_lzma *strm;
+
+		spin_lock(&z_erofs_lzma_lock);
+		strm = z_erofs_lzma_head;
+		if (!strm) {
+			spin_unlock(&z_erofs_lzma_lock);
+			DBG_BUGON(1);
+			return;
+		}
+		z_erofs_lzma_head = NULL;
+		spin_unlock(&z_erofs_lzma_lock);
+
+		while (strm) {
+			struct z_erofs_lzma *n = strm->next;
+
+			if (strm->state)
+				xz_dec_microlzma_end(strm->state);
+			kfree(strm);
+			--z_erofs_lzma_avail_strms;
+			strm = n;
+		}
+	}
+}
+
+static int __init z_erofs_lzma_init(void)
+{
+	unsigned int i;
+
+	/* by default, use # of possible CPUs instead */
+	if (!z_erofs_lzma_nstrms)
+		z_erofs_lzma_nstrms = num_possible_cpus();
+
+	for (i = 0; i < z_erofs_lzma_nstrms; ++i) {
+		struct z_erofs_lzma *strm = kzalloc(sizeof(*strm), GFP_KERNEL);
+
+		if (!strm) {
+			z_erofs_lzma_exit();
+			return -ENOMEM;
+		}
+		spin_lock(&z_erofs_lzma_lock);
+		strm->next = z_erofs_lzma_head;
+		z_erofs_lzma_head = strm;
+		spin_unlock(&z_erofs_lzma_lock);
+		++z_erofs_lzma_avail_strms;
+	}
+	return 0;
+}
+
+static int z_erofs_load_lzma_config(struct super_block *sb,
+			struct erofs_super_block *dsb, void *data, int size)
+{
+	static DEFINE_MUTEX(lzma_resize_mutex);
+	struct z_erofs_lzma_cfgs *lzma = data;
+	unsigned int dict_size, i;
+	struct z_erofs_lzma *strm, *head = NULL;
+	int err;
+
+	if (!lzma || size < sizeof(struct z_erofs_lzma_cfgs)) {
+		erofs_err(sb, "invalid lzma cfgs, size=%u", size);
+		return -EINVAL;
+	}
+	if (lzma->format) {
+		erofs_err(sb, "unidentified lzma format %x, please check kernel version",
+			  le16_to_cpu(lzma->format));
+		return -EINVAL;
+	}
+	dict_size = le32_to_cpu(lzma->dict_size);
+	if (dict_size > Z_EROFS_LZMA_MAX_DICT_SIZE || dict_size < 4096) {
+		erofs_err(sb, "unsupported lzma dictionary size %u",
+			  dict_size);
+		return -EINVAL;
+	}
+
+	/* in case 2 z_erofs_load_lzma_config() race to avoid deadlock */
+	mutex_lock(&lzma_resize_mutex);
+
+	if (z_erofs_lzma_max_dictsize >= dict_size) {
+		mutex_unlock(&lzma_resize_mutex);
+		return 0;
+	}
+
+	/* 1. collect/isolate all streams for the following check */
+	for (i = 0; i < z_erofs_lzma_avail_strms; ++i) {
+		struct z_erofs_lzma *last;
+
+again:
+		spin_lock(&z_erofs_lzma_lock);
+		strm = z_erofs_lzma_head;
+		if (!strm) {
+			spin_unlock(&z_erofs_lzma_lock);
+			wait_event(z_erofs_lzma_wq,
+				   READ_ONCE(z_erofs_lzma_head));
+			goto again;
+		}
+		z_erofs_lzma_head = NULL;
+		spin_unlock(&z_erofs_lzma_lock);
+
+		for (last = strm; last->next; last = last->next)
+			++i;
+		last->next = head;
+		head = strm;
+	}
+
+	err = 0;
+	/* 2. walk each isolated stream and grow max dict_size if needed */
+	for (strm = head; strm; strm = strm->next) {
+		if (strm->state)
+			xz_dec_microlzma_end(strm->state);
+		strm->state = xz_dec_microlzma_alloc(XZ_PREALLOC, dict_size);
+		if (!strm->state)
+			err = -ENOMEM;
+	}
+
+	/* 3. push back all to the global list and update max dict_size */
+	spin_lock(&z_erofs_lzma_lock);
+	DBG_BUGON(z_erofs_lzma_head);
+	z_erofs_lzma_head = head;
+	spin_unlock(&z_erofs_lzma_lock);
+	wake_up_all(&z_erofs_lzma_wq);
+
+	z_erofs_lzma_max_dictsize = dict_size;
+	mutex_unlock(&lzma_resize_mutex);
+	return err;
+}
+
+static const char *z_erofs_lzma_decompress(struct z_erofs_decompress_req *rq,
+					   struct page **pgpl)
+{
+	struct super_block *sb = rq->sb;
+	struct z_erofs_stream_dctx dctx = { .rq = rq, .no = -1, .ni = 0 };
+	struct xz_buf buf = {};
+	struct z_erofs_lzma *strm;
+	enum xz_ret xz_err;
+	const char *reason;
+
+	/* 1. get the exact LZMA compressed size */
+	dctx.kin = kmap_local_page(*rq->in);
+	reason = z_erofs_fixup_insize(rq, dctx.kin + rq->pageofs_in,
+			min(rq->inputsize, sb->s_blocksize - rq->pageofs_in));
+	if (reason) {
+		kunmap_local(dctx.kin);
+		return reason;
+	}
+
+	/* 2. get an available lzma context */
+again:
+	spin_lock(&z_erofs_lzma_lock);
+	strm = z_erofs_lzma_head;
+	if (!strm) {
+		spin_unlock(&z_erofs_lzma_lock);
+		wait_event(z_erofs_lzma_wq, READ_ONCE(z_erofs_lzma_head));
+		goto again;
+	}
+	z_erofs_lzma_head = strm->next;
+	spin_unlock(&z_erofs_lzma_lock);
+
+	/* 3. multi-call decompress */
+	xz_dec_microlzma_reset(strm->state, rq->inputsize, rq->outputsize,
+			       !rq->partial_decoding);
+	buf.in_size = min(rq->inputsize, PAGE_SIZE - rq->pageofs_in);
+	rq->inputsize -= buf.in_size;
+	buf.in = dctx.kin + rq->pageofs_in;
+	dctx.bounce = strm->bounce;
+	do {
+		dctx.avail_out = buf.out_size - buf.out_pos;
+		dctx.inbuf_sz = buf.in_size;
+		dctx.inbuf_pos = buf.in_pos;
+		reason = z_erofs_stream_switch_bufs(&dctx, (void **)&buf.out,
+						    (void **)&buf.in, pgpl);
+		if (reason)
+			break;
+
+		if (buf.out_size == buf.out_pos) {
+			buf.out_size = dctx.avail_out;
+			buf.out_pos = 0;
+		}
+		buf.in_size = dctx.inbuf_sz;
+		buf.in_pos = dctx.inbuf_pos;
+
+		xz_err = xz_dec_microlzma_run(strm->state, &buf);
+		DBG_BUGON(buf.out_pos > buf.out_size);
+		DBG_BUGON(buf.in_pos > buf.in_size);
+
+		if (xz_err != XZ_OK) {
+			if (xz_err == XZ_STREAM_END && !rq->outputsize)
+				break;
+			reason = (xz_err == XZ_DATA_ERROR ?
+				"corrupted compressed data" :
+				"unexpected end of stream");
+			break;
+		}
+	} while (1);
+
+	if (dctx.kout)
+		kunmap_local(dctx.kout);
+	kunmap_local(dctx.kin);
+	/* 4. push back LZMA stream context to the global list */
+	spin_lock(&z_erofs_lzma_lock);
+	strm->next = z_erofs_lzma_head;
+	z_erofs_lzma_head = strm;
+	spin_unlock(&z_erofs_lzma_lock);
+	wake_up(&z_erofs_lzma_wq);
+	return reason;
+}
+
+const struct z_erofs_decompressor z_erofs_lzma_decomp = {
+	.config = z_erofs_load_lzma_config,
+	.decompress = z_erofs_lzma_decompress,
+	.init = z_erofs_lzma_init,
+	.exit = z_erofs_lzma_exit,
+	.name = "lzma"
+};