selftests/bpf: Add a test for objects stuck in free_by_rcu_ttracegrafted

Delete all elements of BPF_F_NO_PREALLOC hash map in one batch. The first
free_bulk() starts RCU tasks trace GP and the rest of the elements are
freed while it's in flight. Wait for call_rcu_ttrace_in_progress to clear
in bpf_mem_cache of every cpu and check that free_by_rcu_ttrace and
waiting_for_gp_ttrace lists are empty.

Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Link: https://lore.kernel.org/bpf/20260930095920.601738-4-alexei.starovoitov@gmail.com
Signed-off-by: Kumar Kartikeya Dwivedi <memxor@gmail.com>

1 files changed, 1055 insertions, 0 deletions

diff --git a/fs/ntfs/lcnalloc.c b/fs/ntfs/lcnalloc.c
new file mode 100644
index 000000000..0d6cd08ee
--- /dev/null
+++ b/fs/ntfs/lcnalloc.c
@@ -0,0 +1,1055 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+/*
+ * Cluster (de)allocation code.
+ *
+ * Copyright (c) 2004-2005 Anton Altaparmakov
+ * Copyright (c) 2025 LG Electronics Co., Ltd.
+ *
+ * Part of this file is based on code from the NTFS-3G.
+ * and is copyrighted by the respective authors below:
+ * Copyright (c) 2002-2004 Anton Altaparmakov
+ * Copyright (c) 2004 Yura Pakhuchiy
+ * Copyright (c) 2004-2008 Szabolcs Szakacsits
+ * Copyright (c) 2008-2009 Jean-Pierre Andre
+ */
+
+#include <linux/blkdev.h>
+
+#include "lcnalloc.h"
+#include "bitmap.h"
+#include "ntfs.h"
+
+/*
+ * ntfs_cluster_free_from_rl_nolock - free clusters from runlist
+ * @vol:	mounted ntfs volume on which to free the clusters
+ * @rl:		runlist describing the clusters to free
+ *
+ * Free all the clusters described by the runlist @rl on the volume @vol.  In
+ * the case of an error being returned, at least some of the clusters were not
+ * freed.
+ *
+ * Return 0 on success and -errno on error.
+ *
+ * Locking: - The volume lcn bitmap must be locked for writing on entry and is
+ *	      left locked on return.
+ */
+int ntfs_cluster_free_from_rl_nolock(struct ntfs_volume *vol,
+		const struct runlist_element *rl)
+{
+	struct inode *lcnbmp_vi = vol->lcnbmp_ino;
+	int ret = 0;
+	s64 nr_freed = 0;
+
+	ntfs_debug("Entering.");
+	if (!rl)
+		return 0;
+
+	if (!NVolFreeClusterKnown(vol))
+		wait_event(vol->free_waitq, NVolFreeClusterKnown(vol));
+
+	for (; rl->length; rl++) {
+		int err;
+
+		if (rl->lcn < 0)
+			continue;
+		err = ntfs_bitmap_clear_run(lcnbmp_vi, rl->lcn, rl->length);
+		if (likely(!err))
+			nr_freed += rl->length;
+		else if (!ret || ret == -ENOMEM)
+			ret = err;
+	}
+	ntfs_inc_free_clusters(vol, nr_freed);
+	ntfs_debug("Done.");
+	return ret;
+}
+
+static s64 max_empty_bit_range(unsigned char *buf, int size)
+{
+	int i, j, run = 0;
+	int max_range = 0;
+	s64 start_pos = -1;
+
+	ntfs_debug("Entering\n");
+
+	i = 0;
+	while (i < size) {
+		switch (*buf) {
+		case 0:
+			do {
+				buf++;
+				run += 8;
+				i++;
+			} while ((i < size) && !*buf);
+			break;
+		case 255:
+			if (run > max_range) {
+				max_range = run;
+				start_pos = (s64)i * 8 - run;
+			}
+			run = 0;
+			do {
+				buf++;
+				i++;
+			} while ((i < size) && (*buf == 255));
+			break;
+		default:
+			for (j = 0; j < 8; j++) {
+				int bit = *buf & (1 << j);
+
+				if (bit) {
+					if (run > max_range) {
+						max_range = run;
+						start_pos = (s64)i * 8 + (j - run);
+					}
+					run = 0;
+				} else
+					run++;
+			}
+			i++;
+			buf++;
+		}
+	}
+
+	if (run > max_range)
+		start_pos = (s64)i * 8 - run;
+
+	return start_pos;
+}
+
+/*
+ * ntfs_cluster_alloc - allocate clusters on an ntfs volume
+ * @vol:		mounted ntfs volume on which to allocate clusters
+ * @start_vcn:		vcn of the first allocated cluster
+ * @count:		number of clusters to allocate
+ * @start_lcn:		starting lcn at which to allocate the clusters or -1 if none
+ * @zone:		zone from which to allocate (MFT_ZONE or DATA_ZONE)
+ * @is_extension:	if true, the caller is extending an attribute
+ * @is_contig:		if true, require contiguous allocation
+ * @is_dealloc:		if true, the allocation is for deallocation purposes
+ *
+ * Allocate @count clusters preferably starting at cluster @start_lcn or at the
+ * current allocator position if @start_lcn is -1, on the mounted ntfs volume
+ * @vol. @zone is either DATA_ZONE for allocation of normal clusters or
+ * MFT_ZONE for allocation of clusters for the master file table, i.e. the
+ * $MFT/$DATA attribute.
+ *
+ * @start_vcn specifies the vcn of the first allocated cluster.  This makes
+ * merging the resulting runlist with the old runlist easier.
+ *
+ * If @is_extension is 'true', the caller is allocating clusters to extend an
+ * attribute and if it is 'false', the caller is allocating clusters to fill a
+ * hole in an attribute.  Practically the difference is that if @is_extension
+ * is 'true' the returned runlist will be terminated with LCN_ENOENT and if
+ * @is_extension is 'false' the runlist will be terminated with
+ * LCN_RL_NOT_MAPPED.
+ *
+ * You need to check the return value with IS_ERR().  If this is false, the
+ * function was successful and the return value is a runlist describing the
+ * allocated cluster(s).  If IS_ERR() is true, the function failed and
+ * PTR_ERR() gives you the error code.
+ *
+ * Notes on the allocation algorithm
+ * =================================
+ *
+ * There are two data zones.  First is the area between the end of the mft zone
+ * and the end of the volume, and second is the area between the start of the
+ * volume and the start of the mft zone.  On unmodified/standard NTFS 1.x
+ * volumes, the second data zone does not exist due to the mft zone being
+ * expanded to cover the start of the volume in order to reserve space for the
+ * mft bitmap attribute.
+ *
+ * This is not the prettiest function but the complexity stems from the need of
+ * implementing the mft vs data zoned approach and from the fact that we have
+ * access to the lcn bitmap in portions of up to 8192 bytes at a time, so we
+ * need to cope with crossing over boundaries of two buffers.  Further, the
+ * fact that the allocator allows for caller supplied hints as to the location
+ * of where allocation should begin and the fact that the allocator keeps track
+ * of where in the data zones the next natural allocation should occur,
+ * contribute to the complexity of the function.  But it should all be
+ * worthwhile, because this allocator should: 1) be a full implementation of
+ * the MFT zone approach used by Windows NT, 2) cause reduction in
+ * fragmentation, and 3) be speedy in allocations (the code is not optimized
+ * for speed, but the algorithm is, so further speed improvements are probably
+ * possible).
+ *
+ * Locking: - The volume lcn bitmap must be unlocked on entry and is unlocked
+ *	      on return.
+ *	    - This function takes the volume lcn bitmap lock for writing and
+ *	      modifies the bitmap contents.
+ *
+ * Return: Runlist describing the allocated cluster(s) on success, error pointer
+ *         on failure.
+ */
+struct runlist_element *ntfs_cluster_alloc(struct ntfs_volume *vol, const s64 start_vcn,
+		const s64 count, const s64 start_lcn,
+		const int zone,
+		const bool is_extension,
+		const bool is_contig,
+		const bool is_dealloc)
+{
+	s64 zone_start, zone_end, bmp_pos, bmp_initial_pos, last_read_pos, lcn;
+	s64 prev_lcn = 0, prev_run_len = 0, mft_zone_size;
+	s64 clusters, free_clusters;
+	loff_t i_size;
+	struct inode *lcnbmp_vi;
+	struct runlist_element *rl = NULL;
+	struct address_space *mapping;
+	struct folio *folio = NULL;
+	u8 *buf = NULL, *byte;
+	int err = 0, rlpos, rlsize, buf_size, pg_off;
+	u8 pass, done_zones, search_zone, need_writeback = 0, bit;
+	unsigned int memalloc_flags;
+	u8 has_guess, used_zone_pos;
+	pgoff_t index;
+
+	ntfs_debug("Entering for start_vcn 0x%llx, count 0x%llx, start_lcn 0x%llx, zone %s_ZONE.",
+			start_vcn, count, start_lcn,
+			zone == MFT_ZONE ? "MFT" : "DATA");
+
+	lcnbmp_vi = vol->lcnbmp_ino;
+	if (start_vcn < 0 || start_lcn < LCN_HOLE ||
+	    zone < FIRST_ZONE || zone > LAST_ZONE)
+		return ERR_PTR(-EINVAL);
+
+	/* Return NULL if @count is zero. */
+	if (count < 0 || !count)
+		return ERR_PTR(-EINVAL);
+
+	memalloc_flags = memalloc_nofs_save();
+
+	if (!NVolFreeClusterKnown(vol))
+		wait_event(vol->free_waitq, NVolFreeClusterKnown(vol));
+	free_clusters = atomic64_read(&vol->free_clusters);
+
+	/* Take the lcnbmp lock for writing. */
+	down_write(&vol->lcnbmp_lock);
+	if (is_dealloc == false)
+		free_clusters -= atomic64_read(&vol->dirty_clusters);
+
+	if (free_clusters < count) {
+		err = -ENOSPC;
+		goto out_restore;
+	}
+
+	/*
+	 * If no specific @start_lcn was requested, use the current data zone
+	 * position, otherwise use the requested @start_lcn but make sure it
+	 * lies outside the mft zone.  Also set done_zones to 0 (no zones done)
+	 * and pass depending on whether we are starting inside a zone (1) or
+	 * at the beginning of a zone (2).  If requesting from the MFT_ZONE,
+	 * we either start at the current position within the mft zone or at
+	 * the specified position.  If the latter is out of bounds then we start
+	 * at the beginning of the MFT_ZONE.
+	 */
+	done_zones = 0;
+	pass = 1;
+	/*
+	 * zone_start and zone_end are the current search range.  search_zone
+	 * is 1 for mft zone, 2 for data zone 1 (end of mft zone till end of
+	 * volume) and 4 for data zone 2 (start of volume till start of mft
+	 * zone).
+	 */
+	has_guess = 1;
+	zone_start = start_lcn;
+
+	if (zone_start < 0) {
+		if (zone == DATA_ZONE)
+			zone_start = vol->data1_zone_pos;
+		else
+			zone_start = vol->mft_zone_pos;
+		if (!zone_start) {
+			/*
+			 * Zone starts at beginning of volume which means a
+			 * single pass is sufficient.
+			 */
+			pass = 2;
+		}
+		has_guess = 0;
+	}
+
+	used_zone_pos = has_guess ? 0 : 1;
+
+	if (!zone_start || zone_start == vol->mft_zone_start ||
+			zone_start == vol->mft_zone_end)
+		pass = 2;
+
+	if (zone_start < vol->mft_zone_start) {
+		zone_end = vol->mft_zone_start;
+		search_zone = 4;
+		/* Skip searching the mft zone. */
+		done_zones |= 1;
+	} else if (zone_start < vol->mft_zone_end) {
+		zone_end = vol->mft_zone_end;
+		search_zone = 1;
+	} else {
+		zone_end = vol->nr_clusters;
+		search_zone = 2;
+		/* Skip searching the mft zone. */
+		done_zones |= 1;
+	}
+
+	/*
+	 * bmp_pos is the current bit position inside the bitmap.  We use
+	 * bmp_initial_pos to determine whether or not to do a zone switch.
+	 */
+	bmp_pos = bmp_initial_pos = zone_start;
+
+	/* Loop until all clusters are allocated, i.e. clusters == 0. */
+	clusters = count;
+	rlpos = rlsize = 0;
+	mapping = lcnbmp_vi->i_mapping;
+	/*
+	 * lcn_empty_bits_per_page is sized from nr_clusters, but $Bitmap can
+	 * cover more clusters than that; bound the scan by the array.
+	 */
+	i_size = min_t(s64, i_size_read(lcnbmp_vi),
+		       ((s64)vol->nr_clusters + 7) >> 3);
+	while (1) {
+		ntfs_debug("Start of outer while loop: done_zones 0x%x, search_zone %i, pass %i, zone_start 0x%llx, zone_end 0x%llx, bmp_initial_pos 0x%llx, bmp_pos 0x%llx, rlpos %i, rlsize %i.",
+				done_zones, search_zone, pass,
+				zone_start, zone_end, bmp_initial_pos,
+				bmp_pos, rlpos, rlsize);
+		/* Loop until we run out of free clusters. */
+		last_read_pos = bmp_pos >> 3;
+		ntfs_debug("last_read_pos 0x%llx.", last_read_pos);
+		if (last_read_pos >= i_size) {
+			ntfs_debug("End of attribute reached. Skipping to zone_pass_done.");
+			goto zone_pass_done;
+		}
+		if (likely(folio)) {
+			if (need_writeback) {
+				ntfs_debug("Marking page dirty.");
+				folio_mark_dirty(folio);
+				need_writeback = 0;
+			}
+			folio_unlock(folio);
+			kunmap_local(buf);
+			folio_put(folio);
+			folio = NULL;
+		}
+
+		index = last_read_pos >> PAGE_SHIFT;
+		pg_off = last_read_pos & ~PAGE_MASK;
+		buf_size = PAGE_SIZE - pg_off;
+		if (unlikely(last_read_pos + buf_size > i_size))
+			buf_size = i_size - last_read_pos;
+		buf_size <<= 3;
+		lcn = bmp_pos & 7;
+		bmp_pos &= ~(s64)7;
+
+		if (vol->lcn_empty_bits_per_page[index] == 0)
+			goto next_bmp_pos;
+
+		folio = read_mapping_folio(mapping, index, NULL);
+		if (IS_ERR(folio)) {
+			err = PTR_ERR(folio);
+			ntfs_error(vol->sb, "Failed to map page.");
+			goto out;
+		}
+
+		folio_lock(folio);
+		buf = kmap_local_folio(folio, 0) + pg_off;
+		ntfs_debug("Before inner while loop: buf_size %i, lcn 0x%llx, bmp_pos 0x%llx, need_writeback %i.",
+				buf_size, lcn, bmp_pos, need_writeback);
+		while (lcn < buf_size && lcn + bmp_pos < zone_end) {
+			byte = buf + (lcn >> 3);
+			ntfs_debug("In inner while loop: buf_size %i, lcn 0x%llx, bmp_pos 0x%llx, need_writeback %i, byte ofs 0x%x, *byte 0x%x.",
+					buf_size, lcn, bmp_pos, need_writeback,
+					(unsigned int)(lcn >> 3),
+					(unsigned int)*byte);
+			bit = 1 << (lcn & 7);
+			ntfs_debug("bit 0x%x.", bit);
+
+			if (has_guess) {
+				if (*byte & bit) {
+					if (is_contig == true && prev_run_len > 0)
+						goto done;
+
+					has_guess = 0;
+					break;
+				}
+			} else {
+				lcn = max_empty_bit_range(buf, buf_size >> 3);
+				if (lcn < 0)
+					break;
+				has_guess = 1;
+				continue;
+			}
+			/*
+			 * Allocate more memory if needed, including space for
+			 * the terminator element.
+			 * kvzalloc() operates on whole pages only.
+			 */
+			if ((rlpos + 2) * sizeof(*rl) > rlsize) {
+				struct runlist_element *rl2;
+
+				ntfs_debug("Reallocating memory.");
+				if (!rl)
+					ntfs_debug("First free bit is at s64 0x%llx.",
+							lcn + bmp_pos);
+				rl2 = kvzalloc(rlsize + PAGE_SIZE, GFP_NOFS);
+				if (unlikely(!rl2)) {
+					err = -ENOMEM;
+					ntfs_error(vol->sb, "Failed to allocate memory.");
+					goto out;
+				}
+				memcpy(rl2, rl, rlsize);
+				kvfree(rl);
+				rl = rl2;
+				rlsize += PAGE_SIZE;
+				ntfs_debug("Reallocated memory, rlsize 0x%x.",
+						rlsize);
+			}
+			/* Allocate the bitmap bit. */
+			*byte |= bit;
+			/* We need to write this bitmap page to disk. */
+			need_writeback = 1;
+			ntfs_debug("*byte 0x%x, need_writeback is set.",
+					(unsigned int)*byte);
+			ntfs_dec_free_clusters(vol, 1);
+			ntfs_set_lcn_empty_bits(vol, index, 1, 1);
+
+			/*
+			 * Coalesce with previous run if adjacent LCNs.
+			 * Otherwise, append a new run.
+			 */
+			ntfs_debug("Adding run (lcn 0x%llx, len 0x%llx), prev_lcn 0x%llx, lcn 0x%llx, bmp_pos 0x%llx, prev_run_len 0x%llx, rlpos %i.",
+					lcn + bmp_pos, 1ULL, prev_lcn,
+					lcn, bmp_pos, prev_run_len, rlpos);
+			if (prev_lcn == lcn + bmp_pos - prev_run_len && rlpos) {
+				ntfs_debug("Coalescing to run (lcn 0x%llx, len 0x%llx).",
+						rl[rlpos - 1].lcn,
+						rl[rlpos - 1].length);
+				rl[rlpos - 1].length = ++prev_run_len;
+				ntfs_debug("Run now (lcn 0x%llx, len 0x%llx), prev_run_len 0x%llx.",
+						rl[rlpos - 1].lcn,
+						rl[rlpos - 1].length,
+						prev_run_len);
+			} else {
+				if (likely(rlpos)) {
+					ntfs_debug("Adding new run, (previous run lcn 0x%llx, len 0x%llx).",
+							rl[rlpos - 1].lcn, rl[rlpos - 1].length);
+					rl[rlpos].vcn = rl[rlpos - 1].vcn +
+							prev_run_len;
+				} else {
+					ntfs_debug("Adding new run, is first run.");
+					rl[rlpos].vcn = start_vcn;
+				}
+				rl[rlpos].lcn = prev_lcn = lcn + bmp_pos;
+				rl[rlpos].length = prev_run_len = 1;
+				rlpos++;
+			}
+			/* Done? */
+			if (!--clusters) {
+				s64 tc;
+done:
+				if (!used_zone_pos)
+					goto out;
+				/*
+				 * Update the current zone position.  Positions
+				 * of already scanned zones have been updated
+				 * during the respective zone switches.
+				 */
+				tc = lcn + bmp_pos + 1;
+				ntfs_debug("Done. Updating current zone position, tc 0x%llx, search_zone %i.",
+						tc, search_zone);
+				switch (search_zone) {
+				case 1:
+					ntfs_debug("Before checks, vol->mft_zone_pos 0x%llx.",
+							vol->mft_zone_pos);
+					if (tc >= vol->mft_zone_end) {
+						vol->mft_zone_pos =
+								vol->mft_lcn;
+						if (!vol->mft_zone_end)
+							vol->mft_zone_pos = 0;
+					} else if ((bmp_initial_pos >=
+							vol->mft_zone_pos ||
+							tc > vol->mft_zone_pos)
+							&& tc >= vol->mft_lcn)
+						vol->mft_zone_pos = tc;
+					ntfs_debug("After checks, vol->mft_zone_pos 0x%llx.",
+							vol->mft_zone_pos);
+					break;
+				case 2:
+					ntfs_debug("Before checks, vol->data1_zone_pos 0x%llx.",
+							vol->data1_zone_pos);
+					if (tc >= vol->nr_clusters)
+						vol->data1_zone_pos =
+							     vol->mft_zone_end;
+					else if ((bmp_initial_pos >=
+						    vol->data1_zone_pos ||
+						    tc > vol->data1_zone_pos)
+						    && tc >= vol->mft_zone_end)
+						vol->data1_zone_pos = tc;
+					ntfs_debug("After checks, vol->data1_zone_pos 0x%llx.",
+							vol->data1_zone_pos);
+					break;
+				case 4:
+					ntfs_debug("Before checks, vol->data2_zone_pos 0x%llx.",
+							vol->data2_zone_pos);
+					if (tc >= vol->mft_zone_start)
+						vol->data2_zone_pos = 0;
+					else if (bmp_initial_pos >=
+						      vol->data2_zone_pos ||
+						      tc > vol->data2_zone_pos)
+						vol->data2_zone_pos = tc;
+					ntfs_debug("After checks, vol->data2_zone_pos 0x%llx.",
+							vol->data2_zone_pos);
+					break;
+				default:
+					WARN_ON(1);
+				}
+				ntfs_debug("Finished.  Going to out.");
+				goto out;
+			}
+			lcn++;
+		}
+
+		if (!used_zone_pos) {
+			used_zone_pos = 1;
+			if (search_zone == 1)
+				zone_start = vol->mft_zone_pos;
+			else if (search_zone == 2)
+				zone_start = vol->data1_zone_pos;
+			else
+				zone_start = vol->data2_zone_pos;
+
+			if (!zone_start || zone_start == vol->mft_zone_start ||
+			    zone_start == vol->mft_zone_end)
+				pass = 2;
+			bmp_pos = zone_start;
+		} else {
+next_bmp_pos:
+			bmp_pos += buf_size;
+		}
+
+		ntfs_debug("After inner while loop: buf_size 0x%x, lcn 0x%llx, bmp_pos 0x%llx, need_writeback %i.",
+				buf_size, lcn, bmp_pos, need_writeback);
+		if (bmp_pos < zone_end) {
+			ntfs_debug("Continuing outer while loop, bmp_pos 0x%llx, zone_end 0x%llx.",
+					bmp_pos, zone_end);
+			continue;
+		}
+zone_pass_done:	/* Finished with the current zone pass. */
+		ntfs_debug("At zone_pass_done, pass %i.", pass);
+		if (pass == 1) {
+			/*
+			 * Now do pass 2, scanning the first part of the zone
+			 * we omitted in pass 1.
+			 */
+			pass = 2;
+			zone_end = zone_start;
+			switch (search_zone) {
+			case 1: /* mft_zone */
+				zone_start = vol->mft_zone_start;
+				break;
+			case 2: /* data1_zone */
+				zone_start = vol->mft_zone_end;
+				break;
+			case 4: /* data2_zone */
+				zone_start = 0;
+				break;
+			default:
+				WARN_ON(1);
+			}
+			/* Sanity check. */
+			if (zone_end < zone_start)
+				zone_end = zone_start;
+			bmp_pos = zone_start;
+			ntfs_debug("Continuing outer while loop, pass 2, zone_start 0x%llx, zone_end 0x%llx, bmp_pos 0x%llx.",
+					zone_start, zone_end, bmp_pos);
+			continue;
+		} /* pass == 2 */
+done_zones_check:
+		ntfs_debug("At done_zones_check, search_zone %i, done_zones before 0x%x, done_zones after 0x%x.",
+				search_zone, done_zones,
+				done_zones | search_zone);
+		done_zones |= search_zone;
+		if (done_zones < 7) {
+			ntfs_debug("Switching zone.");
+			/* Now switch to the next zone we haven't done yet. */
+			pass = 1;
+			switch (search_zone) {
+			case 1:
+				ntfs_debug("Switching from mft zone to data1 zone.");
+				/* Update mft zone position. */
+				if (rlpos && used_zone_pos) {
+					s64 tc;
+
+					ntfs_debug("Before checks, vol->mft_zone_pos 0x%llx.",
+							vol->mft_zone_pos);
+					tc = rl[rlpos - 1].lcn +
+							rl[rlpos - 1].length;
+					if (tc >= vol->mft_zone_end) {
+						vol->mft_zone_pos =
+								vol->mft_lcn;
+						if (!vol->mft_zone_end)
+							vol->mft_zone_pos = 0;
+					} else if ((bmp_initial_pos >=
+							vol->mft_zone_pos ||
+							tc > vol->mft_zone_pos)
+							&& tc >= vol->mft_lcn)
+						vol->mft_zone_pos = tc;
+					ntfs_debug("After checks, vol->mft_zone_pos 0x%llx.",
+							vol->mft_zone_pos);
+				}
+				/* Switch from mft zone to data1 zone. */
+switch_to_data1_zone:		search_zone = 2;
+				zone_start = bmp_initial_pos =
+						vol->data1_zone_pos;
+				zone_end = vol->nr_clusters;
+				if (zone_start == vol->mft_zone_end)
+					pass = 2;
+				if (zone_start >= zone_end) {
+					vol->data1_zone_pos = zone_start =
+							vol->mft_zone_end;
+					pass = 2;
+				}
+				break;
+			case 2:
+				ntfs_debug("Switching from data1 zone to data2 zone.");
+				/* Update data1 zone position. */
+				if (rlpos && used_zone_pos) {
+					s64 tc;
+
+					ntfs_debug("Before checks, vol->data1_zone_pos 0x%llx.",
+							vol->data1_zone_pos);
+					tc = rl[rlpos - 1].lcn +
+							rl[rlpos - 1].length;
+					if (tc >= vol->nr_clusters)
+						vol->data1_zone_pos =
+							     vol->mft_zone_end;
+					else if ((bmp_initial_pos >=
+						    vol->data1_zone_pos ||
+						    tc > vol->data1_zone_pos)
+						    && tc >= vol->mft_zone_end)
+						vol->data1_zone_pos = tc;
+					ntfs_debug("After checks, vol->data1_zone_pos 0x%llx.",
+							vol->data1_zone_pos);
+				}
+				/* Switch from data1 zone to data2 zone. */
+				search_zone = 4;
+				zone_start = bmp_initial_pos =
+						vol->data2_zone_pos;
+				zone_end = vol->mft_zone_start;
+				if (!zone_start)
+					pass = 2;
+				if (zone_start >= zone_end) {
+					vol->data2_zone_pos = zone_start =
+							bmp_initial_pos = 0;
+					pass = 2;
+				}
+				break;
+			case 4:
+				ntfs_debug("Switching from data2 zone to data1 zone.");
+				/* Update data2 zone position. */
+				if (rlpos && used_zone_pos) {
+					s64 tc;
+
+					ntfs_debug("Before checks, vol->data2_zone_pos 0x%llx.",
+							vol->data2_zone_pos);
+					tc = rl[rlpos - 1].lcn +
+							rl[rlpos - 1].length;
+					if (tc >= vol->mft_zone_start)
+						vol->data2_zone_pos = 0;
+					else if (bmp_initial_pos >=
+						      vol->data2_zone_pos ||
+						      tc > vol->data2_zone_pos)
+						vol->data2_zone_pos = tc;
+					ntfs_debug("After checks, vol->data2_zone_pos 0x%llx.",
+							vol->data2_zone_pos);
+				}
+				/* Switch from data2 zone to data1 zone. */
+				goto switch_to_data1_zone;
+			default:
+				WARN_ON(1);
+			}
+			ntfs_debug("After zone switch, search_zone %i, pass %i, bmp_initial_pos 0x%llx, zone_start 0x%llx, zone_end 0x%llx.",
+					search_zone, pass,
+					bmp_initial_pos,
+					zone_start,
+					zone_end);
+			bmp_pos = zone_start;
+			if (zone_start == zone_end) {
+				ntfs_debug("Empty zone, going to done_zones_check.");
+				/* Empty zone. Don't bother searching it. */
+				goto done_zones_check;
+			}
+			ntfs_debug("Continuing outer while loop.");
+			continue;
+		} /* done_zones == 7 */
+		ntfs_debug("All zones are finished.");
+		/*
+		 * All zones are finished!  If DATA_ZONE, shrink mft zone.  If
+		 * MFT_ZONE, we have really run out of space.
+		 */
+		mft_zone_size = vol->mft_zone_end - vol->mft_zone_start;
+		ntfs_debug("vol->mft_zone_start 0x%llx, vol->mft_zone_end 0x%llx, mft_zone_size 0x%llx.",
+				vol->mft_zone_start, vol->mft_zone_end,
+				mft_zone_size);
+		if (zone == MFT_ZONE || mft_zone_size <= 0) {
+			ntfs_debug("No free clusters left, going to out.");
+			/* Really no more space left on device. */
+			err = -ENOSPC;
+			goto out;
+		} /* zone == DATA_ZONE && mft_zone_size > 0 */
+		ntfs_debug("Shrinking mft zone.");
+		zone_end = vol->mft_zone_end;
+		mft_zone_size >>= 1;
+		if (mft_zone_size > 0)
+			vol->mft_zone_end = vol->mft_zone_start + mft_zone_size;
+		else /* mft zone and data2 zone no longer exist. */
+			vol->data2_zone_pos = vol->mft_zone_start =
+					vol->mft_zone_end = 0;
+		if (vol->mft_zone_pos >= vol->mft_zone_end) {
+			vol->mft_zone_pos = vol->mft_lcn;
+			if (!vol->mft_zone_end)
+				vol->mft_zone_pos = 0;
+		}
+		bmp_pos = zone_start = bmp_initial_pos =
+				vol->data1_zone_pos = vol->mft_zone_end;
+		search_zone = 2;
+		pass = 2;
+		done_zones &= ~2;
+		ntfs_debug("After shrinking mft zone, mft_zone_size 0x%llx, vol->mft_zone_start 0x%llx, vol->mft_zone_end 0x%llx, vol->mft_zone_pos 0x%llx, search_zone 2, pass 2, dones_zones 0x%x, zone_start 0x%llx, zone_end 0x%llx, vol->data1_zone_pos 0x%llx, continuing outer while loop.",
+				mft_zone_size, vol->mft_zone_start,
+				vol->mft_zone_end, vol->mft_zone_pos,
+				done_zones, zone_start, zone_end,
+				vol->data1_zone_pos);
+	}
+	ntfs_debug("After outer while loop.");
+out:
+	ntfs_debug("At out.");
+	/* Add runlist terminator element. */
+	if (likely(rl)) {
+		rl[rlpos].vcn = rl[rlpos - 1].vcn + rl[rlpos - 1].length;
+		rl[rlpos].lcn = is_extension ? LCN_ENOENT : LCN_RL_NOT_MAPPED;
+		rl[rlpos].length = 0;
+	}
+	if (!IS_ERR_OR_NULL(folio)) {
+		if (need_writeback) {
+			ntfs_debug("Marking page dirty.");
+			folio_mark_dirty(folio);
+			need_writeback = 0;
+		}
+		folio_unlock(folio);
+		kunmap_local(buf);
+		folio_put(folio);
+	}
+	if (likely(!err)) {
+		if (!rl) {
+			err = -EIO;
+			goto out_restore;
+		}
+		if (is_dealloc == true)
+			ntfs_release_dirty_clusters(vol, rl->length);
+		ntfs_debug("Done.");
+		goto out_restore;
+	}
+	if (err != -ENOSPC)
+		ntfs_error(vol->sb,
+			"Failed to allocate clusters, aborting (error %i).",
+			err);
+	if (rl) {
+		int err2;
+
+		if (err == -ENOSPC)
+			ntfs_debug("Not enough space to complete allocation, err -ENOSPC, first free lcn 0x%llx, could allocate up to 0x%llx clusters.",
+					rl[0].lcn, count - clusters);
+		/* Deallocate all allocated clusters. */
+		ntfs_debug("Attempting rollback...");
+		err2 = ntfs_cluster_free_from_rl_nolock(vol, rl);
+		if (err2) {
+			ntfs_error(vol->sb,
+				"Failed to rollback (error %i). Leaving inconsistent metadata! Unmount and run chkdsk.",
+				err2);
+			NVolSetErrors(vol);
+		}
+		/* Free the runlist. */
+		kvfree(rl);
+	} else if (err == -ENOSPC)
+		ntfs_debug("No space left at all, err = -ENOSPC, first free lcn = 0x%llx.",
+				vol->data1_zone_pos);
+	atomic64_set(&vol->dirty_clusters, 0);
+
+out_restore:
+	up_write(&vol->lcnbmp_lock);
+	memalloc_nofs_restore(memalloc_flags);
+
+	return err < 0 ? ERR_PTR(err) : rl;
+}
+
+/*
+ * __ntfs_cluster_free - free clusters on an ntfs volume
+ * @ni:		ntfs inode whose runlist describes the clusters to free
+ * @start_vcn:	vcn in the runlist of @ni at which to start freeing clusters
+ * @count:	number of clusters to free or -1 for all clusters
+ * @ctx:	active attribute search context if present or NULL if not
+ * @is_rollback:	true if this is a rollback operation
+ *
+ * Free @count clusters starting at the cluster @start_vcn in the runlist
+ * described by the vfs inode @ni.
+ *
+ * If @count is -1, all clusters from @start_vcn to the end of the runlist are
+ * deallocated.  Thus, to completely free all clusters in a runlist, use
+ * @start_vcn = 0 and @count = -1.
+ *
+ * If @ctx is specified, it is an active search context of @ni and its base mft
+ * record.  This is needed when __ntfs_cluster_free() encounters unmapped
+ * runlist fragments and allows their mapping.  If you do not have the mft
+ * record mapped, you can specify @ctx as NULL and __ntfs_cluster_free() will
+ * perform the necessary mapping and unmapping.
+ *
+ * Note, __ntfs_cluster_free() saves the state of @ctx on entry and restores it
+ * before returning.  Thus, @ctx will be left pointing to the same attribute on
+ * return as on entry.  However, the actual pointers in @ctx may point to
+ * different memory locations on return, so you must remember to reset any
+ * cached pointers from the @ctx, i.e. after the call to __ntfs_cluster_free(),
+ * you will probably want to do:
+ *	m = ctx->mrec;
+ *	a = ctx->attr;
+ * Assuming you cache ctx->attr in a variable @a of type attr_record * and that
+ * you cache ctx->mrec in a variable @m of type struct mft_record *.
+ *
+ * @is_rollback should always be 'false', it is for internal use to rollback
+ * errors.  You probably want to use ntfs_cluster_free() instead.
+ *
+ * Note, __ntfs_cluster_free() does not modify the runlist, so you have to
+ * remove from the runlist or mark sparse the freed runs later.
+ *
+ * Return the number of deallocated clusters (not counting sparse ones) on
+ * success and -errno on error.
+ *
+ * WARNING: If @ctx is supplied, regardless of whether success or failure is
+ *	    returned, you need to check IS_ERR(@ctx->mrec) and if 'true' the @ctx
+ *	    is no longer valid, i.e. you need to either call
+ *	    ntfs_attr_reinit_search_ctx() or ntfs_attr_put_search_ctx() on it.
+ *	    In that case PTR_ERR(@ctx->mrec) will give you the error code for
+ *	    why the mapping of the old inode failed.
+ *
+ * Locking: - The runlist described by @ni must be locked for writing on entry
+ *	      and is locked on return.  Note the runlist may be modified when
+ *	      needed runlist fragments need to be mapped.
+ *	    - The volume lcn bitmap must be unlocked on entry and is unlocked
+ *	      on return.
+ *	    - This function takes the volume lcn bitmap lock for writing and
+ *	      modifies the bitmap contents.
+ *	    - If @ctx is NULL, the base mft record of @ni must not be mapped on
+ *	      entry and it will be left unmapped on return.
+ *	    - If @ctx is not NULL, the base mft record must be mapped on entry
+ *	      and it will be left mapped on return.
+ */
+s64 __ntfs_cluster_free(struct ntfs_inode *ni, const s64 start_vcn, s64 count,
+		struct ntfs_attr_search_ctx *ctx, const bool is_rollback)
+{
+	s64 delta, to_free, total_freed, real_freed;
+	struct ntfs_volume *vol;
+	struct inode *lcnbmp_vi;
+	struct runlist_element *rl;
+	int err;
+	unsigned int memalloc_flags;
+
+	ntfs_debug("Entering for i_ino 0x%llx, start_vcn 0x%llx, count 0x%llx.%s",
+			ni->mft_no, start_vcn, count,
+			is_rollback ? " (rollback)" : "");
+	vol = ni->vol;
+	lcnbmp_vi = vol->lcnbmp_ino;
+	if (start_vcn < 0 || count < -1)
+		return -EINVAL;
+
+	if (!NVolFreeClusterKnown(vol))
+		wait_event(vol->free_waitq, NVolFreeClusterKnown(vol));
+
+	/*
+	 * Lock the lcn bitmap for writing but only if not rolling back.  We
+	 * must hold the lock all the way including through rollback otherwise
+	 * rollback is not possible because once we have cleared a bit and
+	 * dropped the lock, anyone could have set the bit again, thus
+	 * allocating the cluster for another use.
+	 */
+	if (likely(!is_rollback)) {
+		memalloc_flags = memalloc_nofs_save();
+		down_write(&vol->lcnbmp_lock);
+	}
+
+	total_freed = real_freed = 0;
+
+	rl = ntfs_attr_find_vcn_nolock(ni, start_vcn, ctx);
+	if (IS_ERR(rl)) {
+		err = PTR_ERR(rl);
+		if (err == -ENOENT) {
+			if (likely(!is_rollback)) {
+				up_write(&vol->lcnbmp_lock);
+				memalloc_nofs_restore(memalloc_flags);
+			}
+			return 0;
+		}
+
+		if (!is_rollback)
+			ntfs_error(vol->sb,
+				"Failed to find first runlist element (error %d), aborting.",
+				err);
+		goto err_out;
+	}
+	if (unlikely(rl->lcn < LCN_HOLE)) {
+		if (!is_rollback)
+			ntfs_error(vol->sb, "First runlist element has invalid lcn, aborting.");
+		err = -EIO;
+		goto err_out;
+	}
+	/* Find the starting cluster inside the run that needs freeing. */
+	delta = start_vcn - rl->vcn;
+
+	/* The number of clusters in this run that need freeing. */
+	to_free = rl->length - delta;
+	if (count >= 0 && to_free > count)
+		to_free = count;
+
+	if (likely(rl->lcn >= 0)) {
+		/* Do the actual freeing of the clusters in this run. */
+		err = ntfs_bitmap_set_bits_in_run(lcnbmp_vi, rl->lcn + delta,
+				to_free, likely(!is_rollback) ? 0 : 1);
+		if (unlikely(err)) {
+			if (!is_rollback)
+				ntfs_error(vol->sb,
+					"Failed to clear first run (error %i), aborting.",
+					err);
+			goto err_out;
+		}
+		/* We have freed @to_free real clusters. */
+		real_freed = to_free;
+	}
+	/* Go to the next run and adjust the number of clusters left to free. */
+	++rl;
+	if (count >= 0)
+		count -= to_free;
+
+	/* Keep track of the total "freed" clusters, including sparse ones. */
+	total_freed = to_free;
+	/*
+	 * Loop over the remaining runs, using @count as a capping value, and
+	 * free them.
+	 */
+	for (; rl->length && count != 0; ++rl) {
+		if (unlikely(rl->lcn < LCN_HOLE)) {
+			s64 vcn;
+
+			/* Attempt to map runlist. */
+			vcn = rl->vcn;
+			rl = ntfs_attr_find_vcn_nolock(ni, vcn, ctx);
+			if (IS_ERR(rl)) {
+				err = PTR_ERR(rl);
+				if (!is_rollback)
+					ntfs_error(vol->sb,
+						"Failed to map runlist fragment or failed to find subsequent runlist element.");
+				goto err_out;
+			}
+			if (unlikely(rl->lcn < LCN_HOLE)) {
+				if (!is_rollback)
+					ntfs_error(vol->sb,
+						"Runlist element has invalid lcn (0x%llx).",
+						rl->lcn);
+				err = -EIO;
+				goto err_out;
+			}
+		}
+		/* The number of clusters in this run that need freeing. */
+		to_free = rl->length;
+		if (count >= 0 && to_free > count)
+			to_free = count;
+
+		if (likely(rl->lcn >= 0)) {
+			/* Do the actual freeing of the clusters in the run. */
+			err = ntfs_bitmap_set_bits_in_run(lcnbmp_vi, rl->lcn,
+					to_free, likely(!is_rollback) ? 0 : 1);
+			if (unlikely(err)) {
+				if (!is_rollback)
+					ntfs_error(vol->sb, "Failed to clear subsequent run.");
+				goto err_out;
+			}
+			/* We have freed @to_free real clusters. */
+			real_freed += to_free;
+		}
+		/* Adjust the number of clusters left to free. */
+		if (count >= 0)
+			count -= to_free;
+
+		/* Update the total done clusters. */
+		total_freed += to_free;
+	}
+	ntfs_inc_free_clusters(vol, real_freed);
+	if (likely(!is_rollback)) {
+		up_write(&vol->lcnbmp_lock);
+		memalloc_nofs_restore(memalloc_flags);
+	}
+
+	WARN_ON(count > 0);
+
+	if (NVolDiscard(vol) && !is_rollback) {
+		s64 total_discarded = 0, rl_off;
+		u32 gran = bdev_discard_granularity(vol->sb->s_bdev);
+
+		rl = ntfs_attr_find_vcn_nolock(ni, start_vcn, ctx);
+		if (IS_ERR(rl))
+			return real_freed;
+		rl_off = start_vcn - rl->vcn;
+		while (rl->length && total_discarded < total_freed) {
+			s64 to_discard = rl->length - rl_off;
+
+			if (to_discard + total_discarded > total_freed)
+				to_discard = total_freed - total_discarded;
+			if (rl->lcn >= 0) {
+				sector_t start_sector, end_sector;
+				int ret;
+
+				start_sector = ALIGN(NTFS_CLU_TO_B(vol, rl->lcn + rl_off),
+						     gran) >> SECTOR_SHIFT;
+				end_sector = ALIGN_DOWN(NTFS_CLU_TO_B(vol,
+							rl->lcn + rl_off + to_discard),
+							gran) >> SECTOR_SHIFT;
+				if (start_sector < end_sector) {
+					ret = blkdev_issue_discard(vol->sb->s_bdev, start_sector,
+								   end_sector - start_sector,
+								   GFP_NOFS);
+					if (ret)
+						break;
+				}
+			}
+
+			total_discarded += to_discard;
+			++rl;
+			rl_off = 0;
+		}
+	}
+
+	/* We are done.  Return the number of actually freed clusters. */
+	ntfs_debug("Done.");
+	return real_freed;
+err_out:
+	if (is_rollback)
+		return err;
+	/* If no real clusters were freed, no need to rollback. */
+	if (!real_freed) {
+		up_write(&vol->lcnbmp_lock);
+		memalloc_nofs_restore(memalloc_flags);
+		return err;
+	}
+	/*
+	 * Attempt to rollback and if that succeeds just return the error code.
+	 * If rollback fails, set the volume errors flag, emit an error
+	 * message, and return the error code.
+	 */
+	delta = __ntfs_cluster_free(ni, start_vcn, total_freed, ctx, true);
+	if (delta < 0) {
+		ntfs_error(vol->sb,
+			"Failed to rollback (error %i).  Leaving inconsistent metadata!  Unmount and run chkdsk.",
+			(int)delta);
+		NVolSetErrors(vol);
+	} else {
+		ntfs_dec_free_clusters(vol, delta);
+	}
+	up_write(&vol->lcnbmp_lock);
+	memalloc_nofs_restore(memalloc_flags);
+	ntfs_error(vol->sb, "Aborting (error %i).", err);
+	return err;
+}