ftrace: Synchronize the initialization of ftrace_opsgrafted

There's some internal state that ftrace_ops needs to have set, but since
it can be declared outside of the ftrace.c code, it calls
ftrace_ops_init() on the ops in every global function. The issue is that
if two tasks call it on the same ops at the same time it is possible to
have the initialization of one corrupt the initialization of the other
call.

Create a ops_mutex to use to synchronize every initialization of the
ftrace_ops. The mutex is taken within checking the ftrace_ops flag that
states it was initializied but the flag is checked again after the mutex
has been taken. Checking first outside the mutex allows it to shortcut
having to take the mutex. But then the check needs to be done again after
the mute is taken in case of races.

Cc: stable@vger.kernel.org
Link: https://patch.msgid.link/20260902095501.6b59af20@gandalf.local.home
Fixes: f04f24fb7e48d ("ftrace, kprobes: Fix a deadlock on ftrace_regex_lock")
Reported-by: sashiko-bot@kernel.org
Close: https://lore.kernel.org/all/20260829025528.49A831F000E9@smtp.kernel.org/
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>

1 files changed, 726 insertions, 0 deletions

diff --git a/fs/ntfs/wof.c b/fs/ntfs/wof.c
new file mode 100644
index 000000000..8f84c2212
--- /dev/null
+++ b/fs/ntfs/wof.c
@@ -0,0 +1,726 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+/*
+ * Windows System Compression (WOF) decompression glue.
+ *
+ * Copyright (c) 2026 LG Electronics Co., Ltd.
+ */
+
+#include <linux/fs.h>
+#include <linux/blkdev.h>
+#include <linux/overflow.h>
+#include <linux/pagemap.h>
+#include <linux/sched/mm.h>
+#include <linux/slab.h>
+#include <linux/unaligned.h>
+#include <linux/vmalloc.h>
+
+#include "ntfs.h"
+#include "inode.h"
+#include "debug.h"
+#include "ntfs_codec.h"
+#include "attrib.h"
+
+static const __le16 WOF_NAME[] = {
+	cpu_to_le16('W'), cpu_to_le16('o'), cpu_to_le16('f'),
+	cpu_to_le16('C'), cpu_to_le16('o'), cpu_to_le16('m'),
+	cpu_to_le16('p'), cpu_to_le16('r'), cpu_to_le16('e'),
+	cpu_to_le16('s'), cpu_to_le16('s'), cpu_to_le16('e'),
+	cpu_to_le16('d'), cpu_to_le16('D'), cpu_to_le16('a'),
+	cpu_to_le16('t'), cpu_to_le16('a'),
+};
+
+#define WOF_NAME_LEN 17
+
+#define NTFS_WOF_MAX_COMP_UNIT (1U << 15)
+#define NTFS_WOF_MAX_PAGES \
+	DIV_ROUND_UP(NTFS_WOF_MAX_COMP_UNIT + PAGE_SIZE - 1, PAGE_SIZE)
+
+struct ntfs_wof_workspace {
+	struct mutex *lock;
+	const struct ntfs_codec_ops *codec;
+	u32 comp_unit;
+	void *input;
+	size_t input_size;
+	void *output;
+	void *scratch;
+};
+
+static DEFINE_MUTEX(ntfs_wof_xpress4k_lock);
+static DEFINE_MUTEX(ntfs_wof_xpress8k_lock);
+static DEFINE_MUTEX(ntfs_wof_xpress16k_lock);
+static DEFINE_MUTEX(ntfs_wof_lzx32k_lock);
+
+static struct ntfs_wof_workspace ntfs_wof_xpress4k_workspace = {
+	.lock = &ntfs_wof_xpress4k_lock,
+	.codec = &ntfs_xpress4k_codec_ops,
+	.comp_unit = 1U << 12,
+};
+
+static struct ntfs_wof_workspace ntfs_wof_xpress8k_workspace = {
+	.lock = &ntfs_wof_xpress8k_lock,
+	.codec = &ntfs_xpress8k_codec_ops,
+	.comp_unit = 1U << 13,
+};
+
+static struct ntfs_wof_workspace ntfs_wof_xpress16k_workspace = {
+	.lock = &ntfs_wof_xpress16k_lock,
+	.codec = &ntfs_xpress16k_codec_ops,
+	.comp_unit = 1U << 14,
+};
+
+static struct ntfs_wof_workspace ntfs_wof_lzx32k_workspace = {
+	.lock = &ntfs_wof_lzx32k_lock,
+	.codec = &ntfs_lzx32k_codec_ops,
+	.comp_unit = 1U << 15,
+};
+
+static struct ntfs_wof_workspace *const ntfs_wof_workspaces[] = {
+	&ntfs_wof_xpress4k_workspace,
+	&ntfs_wof_xpress8k_workspace,
+	&ntfs_wof_xpress16k_workspace,
+	&ntfs_wof_lzx32k_workspace,
+};
+
+static struct ntfs_wof_workspace *ntfs_wof_workspace(u8 block_size_bits)
+{
+	switch (block_size_bits) {
+	case 12:
+		return &ntfs_wof_xpress4k_workspace;
+	case 13:
+		return &ntfs_wof_xpress8k_workspace;
+	case 14:
+		return &ntfs_wof_xpress16k_workspace;
+	case 15:
+		return &ntfs_wof_lzx32k_workspace;
+	default:
+		return NULL;
+	}
+}
+
+static int ntfs_wof_workspace_prepare(struct ntfs_wof_workspace *ws)
+{
+	void *input, *output, *scratch;
+	size_t scratch_size;
+
+	if (ws->input)
+		return 0;
+
+	ws->input_size = round_up((size_t)ws->comp_unit + 511, 512);
+	scratch_size = ws->codec->scratch_size(ws->comp_unit);
+	if (!scratch_size)
+		return -EINVAL;
+
+	input = kvmalloc(ws->input_size, GFP_NOFS);
+	output = kvmalloc(ws->comp_unit, GFP_NOFS);
+	scratch = kvzalloc(scratch_size, GFP_NOFS);
+	if (!input || !output || !scratch) {
+		kvfree(input);
+		kvfree(output);
+		kvfree(scratch);
+		return -ENOMEM;
+	}
+
+	ws->input = input;
+	ws->output = output;
+	ws->scratch = scratch;
+	return 0;
+}
+
+void ntfs_wof_free_workspaces(void)
+{
+	unsigned int i;
+
+	for (i = 0; i < ARRAY_SIZE(ntfs_wof_workspaces); i++) {
+		struct ntfs_wof_workspace *ws = ntfs_wof_workspaces[i];
+
+		mutex_lock(ws->lock);
+		kvfree(ws->input);
+		kvfree(ws->output);
+		kvfree(ws->scratch);
+		ws->input = NULL;
+		ws->output = NULL;
+		ws->scratch = NULL;
+		mutex_unlock(ws->lock);
+	}
+}
+
+static int ntfs_bdev_read_from_rl(struct ntfs_volume *vol,
+				  struct runlist *runlist,
+				  sector_t start_sector, u64 sector_count,
+				  void *buf)
+{
+	struct runlist_element *rl;
+	u32 sec_per_clu_bits;
+	s64 vcn;
+	u64 sec_off;
+	size_t buf_off = 0;
+	unsigned int nofs_flags;
+	int err;
+
+	if (vol->cluster_size_bits < 9)
+		return -EINVAL;
+	sec_per_clu_bits = vol->cluster_size_bits - 9;
+	vcn = start_sector >> sec_per_clu_bits;
+	sec_off = start_sector & ((1ULL << sec_per_clu_bits) - 1);
+
+	nofs_flags = memalloc_nofs_save();
+	down_read(&runlist->lock);
+	if (!runlist->rl) {
+		err = -EINVAL;
+		goto out_unlock;
+	}
+
+	rl = __ntfs_attr_find_vcn_nolock(runlist, vcn);
+	if (IS_ERR(rl)) {
+		err = PTR_ERR(rl);
+		goto out_unlock;
+	}
+
+	while (sector_count > 0) {
+		s64 lcn;
+		s64 rl_end;
+		u64 byte_off, byte_len, sectors, available;
+
+		if (rl->length <= 0 || vcn < rl->vcn) {
+			err = -EINVAL;
+			goto out_unlock;
+		}
+
+		lcn = ntfs_rl_vcn_to_lcn(rl, vcn);
+		if (lcn < 0 && lcn != LCN_HOLE) {
+			err = -EINVAL;
+			goto out_unlock;
+		}
+
+		if (check_add_overflow(rl->vcn, rl->length, &rl_end) ||
+		    rl_end <= vcn ||
+		    (u64)(rl_end - vcn) > (U64_MAX >> sec_per_clu_bits)) {
+			err = -EOVERFLOW;
+			goto out_unlock;
+		}
+		available = (u64)(rl_end - vcn) << sec_per_clu_bits;
+		if (available <= sec_off) {
+			err = -EINVAL;
+			goto out_unlock;
+		}
+		available -= sec_off;
+		sectors = min_t(u64, sector_count, available);
+		if (check_mul_overflow(sectors, (u64)SECTOR_SIZE, &byte_len) ||
+		    byte_len > SIZE_MAX - buf_off) {
+			err = -EOVERFLOW;
+			goto out_unlock;
+		}
+
+		if (lcn == LCN_HOLE) {
+			memset((u8 *)buf + buf_off, 0, byte_len);
+		} else {
+			byte_off = ntfs_cluster_to_bytes(vol, lcn);
+			if (check_add_overflow(byte_off, sec_off << 9,
+					       &byte_off) ||
+			    byte_off > S64_MAX) {
+				err = -EOVERFLOW;
+				goto out_unlock;
+			}
+			err = ntfs_bdev_read(vol->sb->s_bdev,
+					     (char *)buf + buf_off,
+					     (loff_t)byte_off, byte_len);
+			if (err)
+				goto out_unlock;
+		}
+
+		buf_off += byte_len;
+		sector_count -= sectors;
+		rl++;
+		vcn = rl->vcn;
+		sec_off = 0;
+	}
+
+	err = 0;
+out_unlock:
+	up_read(&runlist->lock);
+	memalloc_nofs_restore(nofs_flags);
+	return err;
+}
+
+static int parse_wof_chunk_table(struct ntfs_inode *base_ni,
+				 struct ntfs_inode *ni, u64 chunk_idx,
+				 u64 chunk_count, u32 decomp_size,
+				 u64 *chunk_offset, u32 *chunk_size,
+				 void *table_buf, size_t table_buf_size)
+{
+	u8 bytes_per_off;
+	u8 *buf;
+	u64 off[2];
+	u64 byte_off, chunk_data_size, table_size;
+	u32 bytes_to_read;
+	int ret = 0;
+
+	if (i_size_read(VFS_I(base_ni)) < (1ULL << 32))
+		bytes_per_off = sizeof(__le32);
+	else
+		bytes_per_off = sizeof(__le64);
+
+	if (!chunk_count || chunk_idx >= chunk_count)
+		return -EINVAL;
+
+	table_size = (chunk_count - 1) * bytes_per_off;
+	if (ni->data_size < 0 || (u64)ni->data_size < table_size)
+		return -EINVAL;
+	chunk_data_size = (u64)ni->data_size - table_size;
+
+	if (chunk_count == 1) {
+		if (chunk_data_size > decomp_size)
+			return -EINVAL;
+		*chunk_offset = 0;
+		*chunk_size = chunk_data_size;
+		goto out;
+	}
+
+	byte_off = chunk_idx ? (chunk_idx - 1) * bytes_per_off : 0;
+	bytes_to_read = chunk_idx + 1 == chunk_count ?
+				bytes_per_off :
+				(chunk_idx ? 2 : 1) * bytes_per_off;
+
+	if (NInoNonResident(ni)) {
+		sector_t start_sector = byte_off >> 9;
+		u32 sector_off = byte_off & ((1 << 9) - 1);
+		u32 sectors = DIV_ROUND_UP(sector_off + bytes_to_read, 512);
+
+		if ((size_t)sectors << 9 > table_buf_size)
+			return -EINVAL;
+		buf = table_buf;
+		ret = ntfs_bdev_read_from_rl(ni->vol, &ni->runlist,
+					     start_sector, sectors, buf);
+		if (ret)
+			return -EIO;
+		buf += sector_off;
+	} else {
+		struct ntfs_attr_search_ctx *ctx;
+		u32 value_length;
+		u16 value_offset;
+
+		if (bytes_to_read > table_buf_size)
+			return -EINVAL;
+
+		mutex_lock(&base_ni->mrec_lock);
+		ctx = ntfs_attr_get_search_ctx(base_ni, NULL);
+		if (!ctx) {
+			ret = -ENOMEM;
+			goto out_unlock_mrec;
+		}
+		ret = ntfs_attr_lookup(ni->type, ni->name, ni->name_len,
+				       CASE_SENSITIVE, 0, NULL, 0, ctx);
+		if (ret)
+			goto out_put_ctx;
+
+		value_length =
+			le32_to_cpu(ctx->attr->data.resident.value_length);
+		value_offset =
+			le16_to_cpu(ctx->attr->data.resident.value_offset);
+		if (byte_off + bytes_to_read > value_length) {
+			ret = -EINVAL;
+			goto out_put_ctx;
+		}
+		memcpy(table_buf, (u8 *)ctx->attr + value_offset + byte_off,
+		       bytes_to_read);
+		buf = table_buf;
+out_put_ctx:
+		ntfs_attr_put_search_ctx(ctx);
+out_unlock_mrec:
+		mutex_unlock(&base_ni->mrec_lock);
+		if (ret)
+			return ret;
+	}
+
+	if (bytes_per_off == sizeof(__le32)) {
+		off[0] = chunk_idx ? get_unaligned_le32(buf) : 0;
+		if (chunk_idx + 1 == chunk_count)
+			off[1] = chunk_data_size;
+		else if (chunk_idx)
+			off[1] = get_unaligned_le32(buf + bytes_per_off);
+		else
+			off[1] = get_unaligned_le32(buf);
+	} else {
+		off[0] = chunk_idx ? get_unaligned_le64(buf) : 0;
+		if (chunk_idx + 1 == chunk_count)
+			off[1] = chunk_data_size;
+		else if (chunk_idx)
+			off[1] = get_unaligned_le64(buf + bytes_per_off);
+		else
+			off[1] = get_unaligned_le64(buf);
+	}
+
+	if (off[1] <= off[0] || off[1] > chunk_data_size ||
+	    off[1] - off[0] > decomp_size)
+		return -EINVAL;
+
+	*chunk_offset = table_size + off[0];
+	*chunk_size = off[1] - off[0];
+out:
+	if (!*chunk_size)
+		return -EINVAL;
+	return 0;
+}
+
+static int ntfs_read_wof_chunk(struct ntfs_volume *vol,
+			       struct ntfs_inode *wof_ni, u64 chunk_offset,
+			       u32 chunk_size, void *input, size_t input_size,
+			       char **chunk_mem)
+{
+	struct ntfs_inode *base_ni = wof_ni->ext.base_ntfs_ino;
+	struct ntfs_attr_search_ctx *ctx;
+	u32 input_offset = chunk_offset & 511;
+	u32 input_size_aligned;
+	u32 value_length;
+	u16 value_offset;
+	int err;
+
+	input_size_aligned = round_up(chunk_size + input_offset, 512);
+	if (input_size_aligned > input_size)
+		return -EINVAL;
+
+	if (NInoNonResident(wof_ni)) {
+		err = ntfs_bdev_read_from_rl(vol, &wof_ni->runlist,
+					     chunk_offset >> 9,
+					     input_size_aligned >> 9, input);
+		if (err)
+			return err;
+		*chunk_mem = (u8 *)input + input_offset;
+		return 0;
+	}
+
+	mutex_lock(&base_ni->mrec_lock);
+	ctx = ntfs_attr_get_search_ctx(base_ni, NULL);
+	if (!ctx) {
+		err = -ENOMEM;
+		goto out_unlock_mrec;
+	}
+
+	err = ntfs_attr_lookup(wof_ni->type, wof_ni->name, wof_ni->name_len,
+			       CASE_SENSITIVE, 0, NULL, 0, ctx);
+	if (err)
+		goto out_put_ctx;
+
+	value_length = le32_to_cpu(ctx->attr->data.resident.value_length);
+	value_offset = le16_to_cpu(ctx->attr->data.resident.value_offset);
+	if (chunk_offset + chunk_size > value_length) {
+		err = -EINVAL;
+		goto out_put_ctx;
+	}
+	memcpy(input, (u8 *)ctx->attr + value_offset + chunk_offset,
+	       chunk_size);
+	*chunk_mem = input;
+out_put_ctx:
+	ntfs_attr_put_search_ctx(ctx);
+out_unlock_mrec:
+	mutex_unlock(&base_ni->mrec_lock);
+	return err;
+}
+
+struct ntfs_wof_dest {
+	struct folio *folios[NTFS_WOF_MAX_PAGES];
+	struct page *pages[NTFS_WOF_MAX_PAGES];
+	unsigned int nr_folios;
+	unsigned int nr_pages;
+};
+
+static void ntfs_wof_release_dest(struct ntfs_wof_dest *dest,
+				  struct folio *target, bool success)
+{
+	unsigned int i;
+
+	for (i = 0; i < dest->nr_folios; i++) {
+		struct folio *folio = dest->folios[i];
+
+		if (folio == target)
+			continue;
+		if (success) {
+			flush_dcache_folio(folio);
+			folio_mark_uptodate(folio);
+		} else {
+			folio_clear_uptodate(folio);
+		}
+		folio_unlock(folio);
+		folio_put(folio);
+	}
+}
+
+static int ntfs_wof_collect_dest(struct address_space *mapping,
+				 struct folio *target, loff_t chunk_start,
+				 loff_t chunk_end, struct ntfs_wof_dest *dest)
+{
+	pgoff_t index, last, page_index;
+	unsigned int i;
+
+	memset(dest, 0, sizeof(*dest));
+	index = chunk_start >> PAGE_SHIFT;
+	last = (chunk_end - 1) >> PAGE_SHIFT;
+	while (index <= last) {
+		struct folio *folio;
+		pgoff_t next;
+		bool is_target;
+
+		if (folio_contains(target, index)) {
+			folio = target;
+			is_target = true;
+		} else {
+			folio = __filemap_get_folio(
+				mapping, index,
+				FGP_LOCK | FGP_CREAT | FGP_NOFS | FGP_NOWAIT,
+				GFP_NOFS);
+			if (IS_ERR(folio))
+				return PTR_ERR(folio);
+			is_target = false;
+			if (folio_pos(folio) < chunk_start ||
+			    folio_next_pos(folio) > chunk_end) {
+				folio_unlock(folio);
+				folio_put(folio);
+				return -EAGAIN;
+			}
+		}
+
+		if (dest->nr_folios == ARRAY_SIZE(dest->folios)) {
+			if (!is_target) {
+				folio_unlock(folio);
+				folio_put(folio);
+			}
+			return -EINVAL;
+		}
+		dest->folios[dest->nr_folios++] = folio;
+		next = folio->index + folio_nr_pages(folio);
+		if (next <= index)
+			return -EAGAIN;
+		index = next;
+	}
+
+	for (page_index = chunk_start >> PAGE_SHIFT; page_index <= last;
+	     page_index++) {
+		struct folio *folio = NULL;
+
+		for (i = 0; i < dest->nr_folios; i++) {
+			if (folio_contains(dest->folios[i], page_index)) {
+				folio = dest->folios[i];
+				break;
+			}
+		}
+		if (!folio || dest->nr_pages == ARRAY_SIZE(dest->pages))
+			return -EAGAIN;
+		dest->pages[dest->nr_pages++] =
+			folio_page(folio, page_index - folio->index);
+	}
+	return 0;
+}
+
+static int ntfs_wof_decode(struct ntfs_wof_workspace *ws, const void *src,
+			   u32 src_len, void *dst, u32 dst_len)
+{
+	if (src_len == dst_len) {
+		memcpy(dst, src, dst_len);
+		return 0;
+	}
+	return ws->codec->decompress_chunk(ws->scratch, src, src_len, dst,
+					   dst_len, ws->comp_unit);
+}
+
+static int ntfs_wof_decode_page_direct(struct ntfs_wof_workspace *ws,
+				       struct folio *target, loff_t chunk_start,
+				       const void *src, u32 src_len,
+				       u32 dst_len)
+{
+	unsigned int page_offset = offset_in_page(chunk_start);
+	struct page *page;
+	pgoff_t page_index;
+	void *addr;
+	int err;
+
+	page_index = chunk_start >> PAGE_SHIFT;
+	if (!folio_contains(target, page_index))
+		return -EAGAIN;
+
+	page = folio_page(target, page_index - target->index);
+	addr = kmap_local_page(page);
+	err = ntfs_wof_decode(ws, src, src_len, (u8 *)addr + page_offset,
+			      dst_len);
+	kunmap_local(addr);
+	if (err)
+		return -EINVAL;
+	return 0;
+}
+
+static int ntfs_wof_decode_folios_direct(struct ntfs_wof_workspace *ws,
+					 struct address_space *mapping,
+					 struct folio *target,
+					 loff_t chunk_start, loff_t chunk_end,
+					 const void *src, u32 src_len,
+					 u32 dst_len)
+{
+	unsigned int page_offset = offset_in_page(chunk_start);
+	struct ntfs_wof_dest dest;
+	void *addr;
+	unsigned int nofs_flags;
+	int err;
+
+	err = ntfs_wof_collect_dest(mapping, target, chunk_start, chunk_end,
+				    &dest);
+	if (err) {
+		ntfs_wof_release_dest(&dest, target, false);
+		return -EAGAIN;
+	}
+
+	nofs_flags = memalloc_nofs_save();
+	addr = vmap(dest.pages, dest.nr_pages, VM_MAP, PAGE_KERNEL);
+	memalloc_nofs_restore(nofs_flags);
+	if (!addr) {
+		ntfs_wof_release_dest(&dest, target, false);
+		return -EAGAIN;
+	}
+
+	err = ntfs_wof_decode(ws, src, src_len, (u8 *)addr + page_offset,
+			      dst_len);
+	vunmap(addr);
+	if (err) {
+		ntfs_wof_release_dest(&dest, target, false);
+		return -EINVAL;
+	}
+	ntfs_wof_release_dest(&dest, target, true);
+	return 0;
+}
+
+static int ntfs_wof_try_direct(struct ntfs_wof_workspace *ws,
+			       struct address_space *mapping,
+			       struct folio *target, loff_t chunk_start,
+			       loff_t chunk_end, const void *src, u32 src_len,
+			       u32 dst_len)
+{
+	unsigned int page_offset = offset_in_page(chunk_start);
+
+	if (dst_len <= PAGE_SIZE - page_offset)
+		return ntfs_wof_decode_page_direct(ws, target, chunk_start, src,
+						   src_len, dst_len);
+
+	return ntfs_wof_decode_folios_direct(ws, mapping, target, chunk_start,
+					     chunk_end, src, src_len, dst_len);
+}
+
+int ntfs_read_wof_compressed_block(struct folio *folio)
+{
+	struct address_space *mapping = folio->mapping;
+	struct ntfs_inode *ni = NTFS_I(mapping->host), *wof_ni;
+	struct inode *wof_inode;
+	struct ntfs_volume *vol = ni->vol;
+	struct ntfs_wof_workspace *ws;
+	loff_t i_size = i_size_read(VFS_I(ni));
+	loff_t folio_start = folio_pos(folio);
+	loff_t folio_end = folio_next_pos(folio);
+	char *chunk_mem;
+	u32 decomp_size;
+	u64 chunk_count, chunk_idx, last_chunk, chunk_offset;
+	int err = 0;
+
+	ws = ntfs_wof_workspace(ni->itype.compressed.block_size_bits);
+	if (!ws) {
+		err = -EOPNOTSUPP;
+		goto out;
+	}
+
+	if (folio_start >= i_size) {
+		folio_zero_segment(folio, 0, folio_size(folio));
+		goto out;
+	}
+
+	wof_inode = ntfs_attr_iget(VFS_I(ni), AT_DATA, (__le16 *)WOF_NAME,
+				   WOF_NAME_LEN);
+	if (IS_ERR(wof_inode)) {
+		err = PTR_ERR(wof_inode);
+		goto out;
+	}
+
+	wof_ni = NTFS_I(wof_inode);
+	if (wof_ni->initialized_size != wof_ni->data_size) {
+		ntfs_error(vol->sb,
+			   "WOF compressed stream is not fully initialized (init %lld, data %lld).",
+			   wof_ni->initialized_size, wof_ni->data_size);
+		err = -EIO;
+		goto out_iput;
+	}
+	if (NInoNonResident(wof_ni) && !NInoFullyMapped(wof_ni)) {
+		down_write(&wof_ni->runlist.lock);
+		if (!NInoFullyMapped(wof_ni))
+			err = ntfs_attr_map_whole_runlist(wof_ni);
+		up_write(&wof_ni->runlist.lock);
+		if (err)
+			goto out_iput;
+	}
+
+	mutex_lock(ws->lock);
+	err = ntfs_wof_workspace_prepare(ws);
+	if (err)
+		goto out_unlock_ws;
+
+	chunk_idx = div_u64(folio_start, ws->comp_unit);
+	last_chunk =
+		div_u64(min_t(loff_t, folio_end, i_size) - 1, ws->comp_unit);
+	chunk_count = DIV_ROUND_UP_ULL(i_size, ws->comp_unit);
+	for (; chunk_idx <= last_chunk; chunk_idx++) {
+		u32 chunk_size;
+		u64 chunk_file_offset;
+		loff_t chunk_end, copy_start, copy_end;
+
+		decomp_size = chunk_idx + 1 == chunk_count ?
+				      i_size - chunk_idx * ws->comp_unit :
+				      ws->comp_unit;
+		err = parse_wof_chunk_table(ni, wof_ni, chunk_idx, chunk_count,
+					    decomp_size, &chunk_offset,
+					    &chunk_size, ws->input,
+					    ws->input_size);
+		if (err)
+			goto out_unlock_ws;
+
+		err = ntfs_read_wof_chunk(vol, wof_ni, chunk_offset, chunk_size,
+					  ws->input, ws->input_size,
+					  &chunk_mem);
+		if (err)
+			goto out_unlock_ws;
+
+		chunk_file_offset = chunk_idx * ws->comp_unit;
+		chunk_end = chunk_file_offset + decomp_size;
+		err = ntfs_wof_try_direct(ws, mapping, folio, chunk_file_offset,
+					  chunk_end, chunk_mem, chunk_size,
+					  decomp_size);
+		if (!err)
+			continue;
+		if (err != -EAGAIN)
+			goto out_unlock_ws;
+
+		err = ntfs_wof_decode(ws, chunk_mem, chunk_size, ws->output,
+				      decomp_size);
+		if (err) {
+			ntfs_error(vol->sb, "Decompression failed: %d", err);
+			err = -EINVAL;
+			goto out_unlock_ws;
+		}
+		copy_start = max_t(loff_t, folio_start, chunk_file_offset);
+		copy_end = min_t(loff_t, folio_end,
+				 chunk_file_offset + decomp_size);
+		memcpy_to_folio(folio, copy_start - folio_start,
+				ws->output + copy_start - chunk_file_offset,
+				copy_end - copy_start);
+	}
+
+	if (folio_end > i_size)
+		folio_zero_segment(folio, i_size - folio_start,
+				   folio_size(folio));
+out_unlock_ws:
+	mutex_unlock(ws->lock);
+out_iput:
+	iput(wof_inode);
+out:
+	if (!err) {
+		flush_dcache_folio(folio);
+		folio_mark_uptodate(folio);
+	} else {
+		folio_clear_uptodate(folio);
+	}
+	folio_unlock(folio);
+	return err;
+}