Adding upstream version 6.1.76.upstream/6.1.76

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

1 files changed, 867 insertions, 0 deletions

diff --git a/mm/truncate.c b/mm/truncate.c
new file mode 100644
index 000000000..0d4dd233f
--- /dev/null
+++ b/mm/truncate.c
@@ -0,0 +1,867 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * mm/truncate.c - code for taking down pages from address_spaces
+ *
+ * Copyright (C) 2002, Linus Torvalds
+ *
+ * 10Sep2002	Andrew Morton
+ *		Initial version.
+ */
+
+#include <linux/kernel.h>
+#include <linux/backing-dev.h>
+#include <linux/dax.h>
+#include <linux/gfp.h>
+#include <linux/mm.h>
+#include <linux/swap.h>
+#include <linux/export.h>
+#include <linux/pagemap.h>
+#include <linux/highmem.h>
+#include <linux/pagevec.h>
+#include <linux/task_io_accounting_ops.h>
+#include <linux/shmem_fs.h>
+#include <linux/rmap.h>
+#include "internal.h"
+
+/*
+ * Regular page slots are stabilized by the page lock even without the tree
+ * itself locked.  These unlocked entries need verification under the tree
+ * lock.
+ */
+static inline void __clear_shadow_entry(struct address_space *mapping,
+				pgoff_t index, void *entry)
+{
+	XA_STATE(xas, &mapping->i_pages, index);
+
+	xas_set_update(&xas, workingset_update_node);
+	if (xas_load(&xas) != entry)
+		return;
+	xas_store(&xas, NULL);
+}
+
+static void clear_shadow_entry(struct address_space *mapping, pgoff_t index,
+			       void *entry)
+{
+	spin_lock(&mapping->host->i_lock);
+	xa_lock_irq(&mapping->i_pages);
+	__clear_shadow_entry(mapping, index, entry);
+	xa_unlock_irq(&mapping->i_pages);
+	if (mapping_shrinkable(mapping))
+		inode_add_lru(mapping->host);
+	spin_unlock(&mapping->host->i_lock);
+}
+
+/*
+ * Unconditionally remove exceptional entries. Usually called from truncate
+ * path. Note that the folio_batch may be altered by this function by removing
+ * exceptional entries similar to what folio_batch_remove_exceptionals() does.
+ */
+static void truncate_folio_batch_exceptionals(struct address_space *mapping,
+				struct folio_batch *fbatch, pgoff_t *indices)
+{
+	int i, j;
+	bool dax;
+
+	/* Handled by shmem itself */
+	if (shmem_mapping(mapping))
+		return;
+
+	for (j = 0; j < folio_batch_count(fbatch); j++)
+		if (xa_is_value(fbatch->folios[j]))
+			break;
+
+	if (j == folio_batch_count(fbatch))
+		return;
+
+	dax = dax_mapping(mapping);
+	if (!dax) {
+		spin_lock(&mapping->host->i_lock);
+		xa_lock_irq(&mapping->i_pages);
+	}
+
+	for (i = j; i < folio_batch_count(fbatch); i++) {
+		struct folio *folio = fbatch->folios[i];
+		pgoff_t index = indices[i];
+
+		if (!xa_is_value(folio)) {
+			fbatch->folios[j++] = folio;
+			continue;
+		}
+
+		if (unlikely(dax)) {
+			dax_delete_mapping_entry(mapping, index);
+			continue;
+		}
+
+		__clear_shadow_entry(mapping, index, folio);
+	}
+
+	if (!dax) {
+		xa_unlock_irq(&mapping->i_pages);
+		if (mapping_shrinkable(mapping))
+			inode_add_lru(mapping->host);
+		spin_unlock(&mapping->host->i_lock);
+	}
+	fbatch->nr = j;
+}
+
+/*
+ * Invalidate exceptional entry if easily possible. This handles exceptional
+ * entries for invalidate_inode_pages().
+ */
+static int invalidate_exceptional_entry(struct address_space *mapping,
+					pgoff_t index, void *entry)
+{
+	/* Handled by shmem itself, or for DAX we do nothing. */
+	if (shmem_mapping(mapping) || dax_mapping(mapping))
+		return 1;
+	clear_shadow_entry(mapping, index, entry);
+	return 1;
+}
+
+/*
+ * Invalidate exceptional entry if clean. This handles exceptional entries for
+ * invalidate_inode_pages2() so for DAX it evicts only clean entries.
+ */
+static int invalidate_exceptional_entry2(struct address_space *mapping,
+					 pgoff_t index, void *entry)
+{
+	/* Handled by shmem itself */
+	if (shmem_mapping(mapping))
+		return 1;
+	if (dax_mapping(mapping))
+		return dax_invalidate_mapping_entry_sync(mapping, index);
+	clear_shadow_entry(mapping, index, entry);
+	return 1;
+}
+
+/**
+ * folio_invalidate - Invalidate part or all of a folio.
+ * @folio: The folio which is affected.
+ * @offset: start of the range to invalidate
+ * @length: length of the range to invalidate
+ *
+ * folio_invalidate() is called when all or part of the folio has become
+ * invalidated by a truncate operation.
+ *
+ * folio_invalidate() does not have to release all buffers, but it must
+ * ensure that no dirty buffer is left outside @offset and that no I/O
+ * is underway against any of the blocks which are outside the truncation
+ * point.  Because the caller is about to free (and possibly reuse) those
+ * blocks on-disk.
+ */
+void folio_invalidate(struct folio *folio, size_t offset, size_t length)
+{
+	const struct address_space_operations *aops = folio->mapping->a_ops;
+
+	if (aops->invalidate_folio)
+		aops->invalidate_folio(folio, offset, length);
+}
+EXPORT_SYMBOL_GPL(folio_invalidate);
+
+/*
+ * If truncate cannot remove the fs-private metadata from the page, the page
+ * becomes orphaned.  It will be left on the LRU and may even be mapped into
+ * user pagetables if we're racing with filemap_fault().
+ *
+ * We need to bail out if page->mapping is no longer equal to the original
+ * mapping.  This happens a) when the VM reclaimed the page while we waited on
+ * its lock, b) when a concurrent invalidate_mapping_pages got there first and
+ * c) when tmpfs swizzles a page between a tmpfs inode and swapper_space.
+ */
+static void truncate_cleanup_folio(struct folio *folio)
+{
+	if (folio_mapped(folio))
+		unmap_mapping_folio(folio);
+
+	if (folio_has_private(folio))
+		folio_invalidate(folio, 0, folio_size(folio));
+
+	/*
+	 * Some filesystems seem to re-dirty the page even after
+	 * the VM has canceled the dirty bit (eg ext3 journaling).
+	 * Hence dirty accounting check is placed after invalidation.
+	 */
+	folio_cancel_dirty(folio);
+	folio_clear_mappedtodisk(folio);
+}
+
+int truncate_inode_folio(struct address_space *mapping, struct folio *folio)
+{
+	if (folio->mapping != mapping)
+		return -EIO;
+
+	truncate_cleanup_folio(folio);
+	filemap_remove_folio(folio);
+	return 0;
+}
+
+/*
+ * Handle partial folios.  The folio may be entirely within the
+ * range if a split has raced with us.  If not, we zero the part of the
+ * folio that's within the [start, end] range, and then split the folio if
+ * it's large.  split_page_range() will discard pages which now lie beyond
+ * i_size, and we rely on the caller to discard pages which lie within a
+ * newly created hole.
+ *
+ * Returns false if splitting failed so the caller can avoid
+ * discarding the entire folio which is stubbornly unsplit.
+ */
+bool truncate_inode_partial_folio(struct folio *folio, loff_t start, loff_t end)
+{
+	loff_t pos = folio_pos(folio);
+	unsigned int offset, length;
+
+	if (pos < start)
+		offset = start - pos;
+	else
+		offset = 0;
+	length = folio_size(folio);
+	if (pos + length <= (u64)end)
+		length = length - offset;
+	else
+		length = end + 1 - pos - offset;
+
+	folio_wait_writeback(folio);
+	if (length == folio_size(folio)) {
+		truncate_inode_folio(folio->mapping, folio);
+		return true;
+	}
+
+	/*
+	 * We may be zeroing pages we're about to discard, but it avoids
+	 * doing a complex calculation here, and then doing the zeroing
+	 * anyway if the page split fails.
+	 */
+	folio_zero_range(folio, offset, length);
+
+	if (folio_has_private(folio))
+		folio_invalidate(folio, offset, length);
+	if (!folio_test_large(folio))
+		return true;
+	if (split_folio(folio) == 0)
+		return true;
+	if (folio_test_dirty(folio))
+		return false;
+	truncate_inode_folio(folio->mapping, folio);
+	return true;
+}
+
+/*
+ * Used to get rid of pages on hardware memory corruption.
+ */
+int generic_error_remove_page(struct address_space *mapping, struct page *page)
+{
+	VM_BUG_ON_PAGE(PageTail(page), page);
+
+	if (!mapping)
+		return -EINVAL;
+	/*
+	 * Only punch for normal data pages for now.
+	 * Handling other types like directories would need more auditing.
+	 */
+	if (!S_ISREG(mapping->host->i_mode))
+		return -EIO;
+	return truncate_inode_folio(mapping, page_folio(page));
+}
+EXPORT_SYMBOL(generic_error_remove_page);
+
+static long mapping_evict_folio(struct address_space *mapping,
+		struct folio *folio)
+{
+	if (folio_test_dirty(folio) || folio_test_writeback(folio))
+		return 0;
+	/* The refcount will be elevated if any page in the folio is mapped */
+	if (folio_ref_count(folio) >
+			folio_nr_pages(folio) + folio_has_private(folio) + 1)
+		return 0;
+	if (!filemap_release_folio(folio, 0))
+		return 0;
+
+	return remove_mapping(mapping, folio);
+}
+
+/**
+ * invalidate_inode_page() - Remove an unused page from the pagecache.
+ * @page: The page to remove.
+ *
+ * Safely invalidate one page from its pagecache mapping.
+ * It only drops clean, unused pages.
+ *
+ * Context: Page must be locked.
+ * Return: The number of pages successfully removed.
+ */
+long invalidate_inode_page(struct page *page)
+{
+	struct folio *folio = page_folio(page);
+	struct address_space *mapping = folio_mapping(folio);
+
+	/* The page may have been truncated before it was locked */
+	if (!mapping)
+		return 0;
+	return mapping_evict_folio(mapping, folio);
+}
+
+/**
+ * truncate_inode_pages_range - truncate range of pages specified by start & end byte offsets
+ * @mapping: mapping to truncate
+ * @lstart: offset from which to truncate
+ * @lend: offset to which to truncate (inclusive)
+ *
+ * Truncate the page cache, removing the pages that are between
+ * specified offsets (and zeroing out partial pages
+ * if lstart or lend + 1 is not page aligned).
+ *
+ * Truncate takes two passes - the first pass is nonblocking.  It will not
+ * block on page locks and it will not block on writeback.  The second pass
+ * will wait.  This is to prevent as much IO as possible in the affected region.
+ * The first pass will remove most pages, so the search cost of the second pass
+ * is low.
+ *
+ * We pass down the cache-hot hint to the page freeing code.  Even if the
+ * mapping is large, it is probably the case that the final pages are the most
+ * recently touched, and freeing happens in ascending file offset order.
+ *
+ * Note that since ->invalidate_folio() accepts range to invalidate
+ * truncate_inode_pages_range is able to handle cases where lend + 1 is not
+ * page aligned properly.
+ */
+void truncate_inode_pages_range(struct address_space *mapping,
+				loff_t lstart, loff_t lend)
+{
+	pgoff_t		start;		/* inclusive */
+	pgoff_t		end;		/* exclusive */
+	struct folio_batch fbatch;
+	pgoff_t		indices[PAGEVEC_SIZE];
+	pgoff_t		index;
+	int		i;
+	struct folio	*folio;
+	bool		same_folio;
+
+	if (mapping_empty(mapping))
+		return;
+
+	/*
+	 * 'start' and 'end' always covers the range of pages to be fully
+	 * truncated. Partial pages are covered with 'partial_start' at the
+	 * start of the range and 'partial_end' at the end of the range.
+	 * Note that 'end' is exclusive while 'lend' is inclusive.
+	 */
+	start = (lstart + PAGE_SIZE - 1) >> PAGE_SHIFT;
+	if (lend == -1)
+		/*
+		 * lend == -1 indicates end-of-file so we have to set 'end'
+		 * to the highest possible pgoff_t and since the type is
+		 * unsigned we're using -1.
+		 */
+		end = -1;
+	else
+		end = (lend + 1) >> PAGE_SHIFT;
+
+	folio_batch_init(&fbatch);
+	index = start;
+	while (index < end && find_lock_entries(mapping, index, end - 1,
+			&fbatch, indices)) {
+		index = indices[folio_batch_count(&fbatch) - 1] + 1;
+		truncate_folio_batch_exceptionals(mapping, &fbatch, indices);
+		for (i = 0; i < folio_batch_count(&fbatch); i++)
+			truncate_cleanup_folio(fbatch.folios[i]);
+		delete_from_page_cache_batch(mapping, &fbatch);
+		for (i = 0; i < folio_batch_count(&fbatch); i++)
+			folio_unlock(fbatch.folios[i]);
+		folio_batch_release(&fbatch);
+		cond_resched();
+	}
+
+	same_folio = (lstart >> PAGE_SHIFT) == (lend >> PAGE_SHIFT);
+	folio = __filemap_get_folio(mapping, lstart >> PAGE_SHIFT, FGP_LOCK, 0);
+	if (folio) {
+		same_folio = lend < folio_pos(folio) + folio_size(folio);
+		if (!truncate_inode_partial_folio(folio, lstart, lend)) {
+			start = folio->index + folio_nr_pages(folio);
+			if (same_folio)
+				end = folio->index;
+		}
+		folio_unlock(folio);
+		folio_put(folio);
+		folio = NULL;
+	}
+
+	if (!same_folio)
+		folio = __filemap_get_folio(mapping, lend >> PAGE_SHIFT,
+						FGP_LOCK, 0);
+	if (folio) {
+		if (!truncate_inode_partial_folio(folio, lstart, lend))
+			end = folio->index;
+		folio_unlock(folio);
+		folio_put(folio);
+	}
+
+	index = start;
+	while (index < end) {
+		cond_resched();
+		if (!find_get_entries(mapping, index, end - 1, &fbatch,
+				indices)) {
+			/* If all gone from start onwards, we're done */
+			if (index == start)
+				break;
+			/* Otherwise restart to make sure all gone */
+			index = start;
+			continue;
+		}
+
+		for (i = 0; i < folio_batch_count(&fbatch); i++) {
+			struct folio *folio = fbatch.folios[i];
+
+			/* We rely upon deletion not changing page->index */
+			index = indices[i];
+
+			if (xa_is_value(folio))
+				continue;
+
+			folio_lock(folio);
+			VM_BUG_ON_FOLIO(!folio_contains(folio, index), folio);
+			folio_wait_writeback(folio);
+			truncate_inode_folio(mapping, folio);
+			folio_unlock(folio);
+			index = folio_index(folio) + folio_nr_pages(folio) - 1;
+		}
+		truncate_folio_batch_exceptionals(mapping, &fbatch, indices);
+		folio_batch_release(&fbatch);
+		index++;
+	}
+}
+EXPORT_SYMBOL(truncate_inode_pages_range);
+
+/**
+ * truncate_inode_pages - truncate *all* the pages from an offset
+ * @mapping: mapping to truncate
+ * @lstart: offset from which to truncate
+ *
+ * Called under (and serialised by) inode->i_rwsem and
+ * mapping->invalidate_lock.
+ *
+ * Note: When this function returns, there can be a page in the process of
+ * deletion (inside __filemap_remove_folio()) in the specified range.  Thus
+ * mapping->nrpages can be non-zero when this function returns even after
+ * truncation of the whole mapping.
+ */
+void truncate_inode_pages(struct address_space *mapping, loff_t lstart)
+{
+	truncate_inode_pages_range(mapping, lstart, (loff_t)-1);
+}
+EXPORT_SYMBOL(truncate_inode_pages);
+
+/**
+ * truncate_inode_pages_final - truncate *all* pages before inode dies
+ * @mapping: mapping to truncate
+ *
+ * Called under (and serialized by) inode->i_rwsem.
+ *
+ * Filesystems have to use this in the .evict_inode path to inform the
+ * VM that this is the final truncate and the inode is going away.
+ */
+void truncate_inode_pages_final(struct address_space *mapping)
+{
+	/*
+	 * Page reclaim can not participate in regular inode lifetime
+	 * management (can't call iput()) and thus can race with the
+	 * inode teardown.  Tell it when the address space is exiting,
+	 * so that it does not install eviction information after the
+	 * final truncate has begun.
+	 */
+	mapping_set_exiting(mapping);
+
+	if (!mapping_empty(mapping)) {
+		/*
+		 * As truncation uses a lockless tree lookup, cycle
+		 * the tree lock to make sure any ongoing tree
+		 * modification that does not see AS_EXITING is
+		 * completed before starting the final truncate.
+		 */
+		xa_lock_irq(&mapping->i_pages);
+		xa_unlock_irq(&mapping->i_pages);
+	}
+
+	truncate_inode_pages(mapping, 0);
+}
+EXPORT_SYMBOL(truncate_inode_pages_final);
+
+/**
+ * invalidate_mapping_pagevec - Invalidate all the unlocked pages of one inode
+ * @mapping: the address_space which holds the pages to invalidate
+ * @start: the offset 'from' which to invalidate
+ * @end: the offset 'to' which to invalidate (inclusive)
+ * @nr_pagevec: invalidate failed page number for caller
+ *
+ * This helper is similar to invalidate_mapping_pages(), except that it accounts
+ * for pages that are likely on a pagevec and counts them in @nr_pagevec, which
+ * will be used by the caller.
+ */
+unsigned long invalidate_mapping_pagevec(struct address_space *mapping,
+		pgoff_t start, pgoff_t end, unsigned long *nr_pagevec)
+{
+	pgoff_t indices[PAGEVEC_SIZE];
+	struct folio_batch fbatch;
+	pgoff_t index = start;
+	unsigned long ret;
+	unsigned long count = 0;
+	int i;
+
+	folio_batch_init(&fbatch);
+	while (find_lock_entries(mapping, index, end, &fbatch, indices)) {
+		for (i = 0; i < folio_batch_count(&fbatch); i++) {
+			struct folio *folio = fbatch.folios[i];
+
+			/* We rely upon deletion not changing folio->index */
+			index = indices[i];
+
+			if (xa_is_value(folio)) {
+				count += invalidate_exceptional_entry(mapping,
+								      index,
+								      folio);
+				continue;
+			}
+			index += folio_nr_pages(folio) - 1;
+
+			ret = mapping_evict_folio(mapping, folio);
+			folio_unlock(folio);
+			/*
+			 * Invalidation is a hint that the folio is no longer
+			 * of interest and try to speed up its reclaim.
+			 */
+			if (!ret) {
+				deactivate_file_folio(folio);
+				/* It is likely on the pagevec of a remote CPU */
+				if (nr_pagevec)
+					(*nr_pagevec)++;
+			}
+			count += ret;
+		}
+		folio_batch_remove_exceptionals(&fbatch);
+		folio_batch_release(&fbatch);
+		cond_resched();
+		index++;
+	}
+	return count;
+}
+
+/**
+ * invalidate_mapping_pages - Invalidate all clean, unlocked cache of one inode
+ * @mapping: the address_space which holds the cache to invalidate
+ * @start: the offset 'from' which to invalidate
+ * @end: the offset 'to' which to invalidate (inclusive)
+ *
+ * This function removes pages that are clean, unmapped and unlocked,
+ * as well as shadow entries. It will not block on IO activity.
+ *
+ * If you want to remove all the pages of one inode, regardless of
+ * their use and writeback state, use truncate_inode_pages().
+ *
+ * Return: the number of the cache entries that were invalidated
+ */
+unsigned long invalidate_mapping_pages(struct address_space *mapping,
+		pgoff_t start, pgoff_t end)
+{
+	return invalidate_mapping_pagevec(mapping, start, end, NULL);
+}
+EXPORT_SYMBOL(invalidate_mapping_pages);
+
+/*
+ * This is like invalidate_inode_page(), except it ignores the page's
+ * refcount.  We do this because invalidate_inode_pages2() needs stronger
+ * invalidation guarantees, and cannot afford to leave pages behind because
+ * shrink_page_list() has a temp ref on them, or because they're transiently
+ * sitting in the lru_cache_add() pagevecs.
+ */
+static int invalidate_complete_folio2(struct address_space *mapping,
+					struct folio *folio)
+{
+	if (folio->mapping != mapping)
+		return 0;
+
+	if (!filemap_release_folio(folio, GFP_KERNEL))
+		return 0;
+
+	spin_lock(&mapping->host->i_lock);
+	xa_lock_irq(&mapping->i_pages);
+	if (folio_test_dirty(folio))
+		goto failed;
+
+	BUG_ON(folio_has_private(folio));
+	__filemap_remove_folio(folio, NULL);
+	xa_unlock_irq(&mapping->i_pages);
+	if (mapping_shrinkable(mapping))
+		inode_add_lru(mapping->host);
+	spin_unlock(&mapping->host->i_lock);
+
+	filemap_free_folio(mapping, folio);
+	return 1;
+failed:
+	xa_unlock_irq(&mapping->i_pages);
+	spin_unlock(&mapping->host->i_lock);
+	return 0;
+}
+
+static int folio_launder(struct address_space *mapping, struct folio *folio)
+{
+	if (!folio_test_dirty(folio))
+		return 0;
+	if (folio->mapping != mapping || mapping->a_ops->launder_folio == NULL)
+		return 0;
+	return mapping->a_ops->launder_folio(folio);
+}
+
+/**
+ * invalidate_inode_pages2_range - remove range of pages from an address_space
+ * @mapping: the address_space
+ * @start: the page offset 'from' which to invalidate
+ * @end: the page offset 'to' which to invalidate (inclusive)
+ *
+ * Any pages which are found to be mapped into pagetables are unmapped prior to
+ * invalidation.
+ *
+ * Return: -EBUSY if any pages could not be invalidated.
+ */
+int invalidate_inode_pages2_range(struct address_space *mapping,
+				  pgoff_t start, pgoff_t end)
+{
+	pgoff_t indices[PAGEVEC_SIZE];
+	struct folio_batch fbatch;
+	pgoff_t index;
+	int i;
+	int ret = 0;
+	int ret2 = 0;
+	int did_range_unmap = 0;
+
+	if (mapping_empty(mapping))
+		return 0;
+
+	folio_batch_init(&fbatch);
+	index = start;
+	while (find_get_entries(mapping, index, end, &fbatch, indices)) {
+		for (i = 0; i < folio_batch_count(&fbatch); i++) {
+			struct folio *folio = fbatch.folios[i];
+
+			/* We rely upon deletion not changing folio->index */
+			index = indices[i];
+
+			if (xa_is_value(folio)) {
+				if (!invalidate_exceptional_entry2(mapping,
+						index, folio))
+					ret = -EBUSY;
+				continue;
+			}
+
+			if (!did_range_unmap && folio_mapped(folio)) {
+				/*
+				 * If folio is mapped, before taking its lock,
+				 * zap the rest of the file in one hit.
+				 */
+				unmap_mapping_pages(mapping, index,
+						(1 + end - index), false);
+				did_range_unmap = 1;
+			}
+
+			folio_lock(folio);
+			VM_BUG_ON_FOLIO(!folio_contains(folio, index), folio);
+			if (folio->mapping != mapping) {
+				folio_unlock(folio);
+				continue;
+			}
+			folio_wait_writeback(folio);
+
+			if (folio_mapped(folio))
+				unmap_mapping_folio(folio);
+			BUG_ON(folio_mapped(folio));
+
+			ret2 = folio_launder(mapping, folio);
+			if (ret2 == 0) {
+				if (!invalidate_complete_folio2(mapping, folio))
+					ret2 = -EBUSY;
+			}
+			if (ret2 < 0)
+				ret = ret2;
+			folio_unlock(folio);
+		}
+		folio_batch_remove_exceptionals(&fbatch);
+		folio_batch_release(&fbatch);
+		cond_resched();
+		index++;
+	}
+	/*
+	 * For DAX we invalidate page tables after invalidating page cache.  We
+	 * could invalidate page tables while invalidating each entry however
+	 * that would be expensive. And doing range unmapping before doesn't
+	 * work as we have no cheap way to find whether page cache entry didn't
+	 * get remapped later.
+	 */
+	if (dax_mapping(mapping)) {
+		unmap_mapping_pages(mapping, start, end - start + 1, false);
+	}
+	return ret;
+}
+EXPORT_SYMBOL_GPL(invalidate_inode_pages2_range);
+
+/**
+ * invalidate_inode_pages2 - remove all pages from an address_space
+ * @mapping: the address_space
+ *
+ * Any pages which are found to be mapped into pagetables are unmapped prior to
+ * invalidation.
+ *
+ * Return: -EBUSY if any pages could not be invalidated.
+ */
+int invalidate_inode_pages2(struct address_space *mapping)
+{
+	return invalidate_inode_pages2_range(mapping, 0, -1);
+}
+EXPORT_SYMBOL_GPL(invalidate_inode_pages2);
+
+/**
+ * truncate_pagecache - unmap and remove pagecache that has been truncated
+ * @inode: inode
+ * @newsize: new file size
+ *
+ * inode's new i_size must already be written before truncate_pagecache
+ * is called.
+ *
+ * This function should typically be called before the filesystem
+ * releases resources associated with the freed range (eg. deallocates
+ * blocks). This way, pagecache will always stay logically coherent
+ * with on-disk format, and the filesystem would not have to deal with
+ * situations such as writepage being called for a page that has already
+ * had its underlying blocks deallocated.
+ */
+void truncate_pagecache(struct inode *inode, loff_t newsize)
+{
+	struct address_space *mapping = inode->i_mapping;
+	loff_t holebegin = round_up(newsize, PAGE_SIZE);
+
+	/*
+	 * unmap_mapping_range is called twice, first simply for
+	 * efficiency so that truncate_inode_pages does fewer
+	 * single-page unmaps.  However after this first call, and
+	 * before truncate_inode_pages finishes, it is possible for
+	 * private pages to be COWed, which remain after
+	 * truncate_inode_pages finishes, hence the second
+	 * unmap_mapping_range call must be made for correctness.
+	 */
+	unmap_mapping_range(mapping, holebegin, 0, 1);
+	truncate_inode_pages(mapping, newsize);
+	unmap_mapping_range(mapping, holebegin, 0, 1);
+}
+EXPORT_SYMBOL(truncate_pagecache);
+
+/**
+ * truncate_setsize - update inode and pagecache for a new file size
+ * @inode: inode
+ * @newsize: new file size
+ *
+ * truncate_setsize updates i_size and performs pagecache truncation (if
+ * necessary) to @newsize. It will be typically be called from the filesystem's
+ * setattr function when ATTR_SIZE is passed in.
+ *
+ * Must be called with a lock serializing truncates and writes (generally
+ * i_rwsem but e.g. xfs uses a different lock) and before all filesystem
+ * specific block truncation has been performed.
+ */
+void truncate_setsize(struct inode *inode, loff_t newsize)
+{
+	loff_t oldsize = inode->i_size;
+
+	i_size_write(inode, newsize);
+	if (newsize > oldsize)
+		pagecache_isize_extended(inode, oldsize, newsize);
+	truncate_pagecache(inode, newsize);
+}
+EXPORT_SYMBOL(truncate_setsize);
+
+/**
+ * pagecache_isize_extended - update pagecache after extension of i_size
+ * @inode:	inode for which i_size was extended
+ * @from:	original inode size
+ * @to:		new inode size
+ *
+ * Handle extension of inode size either caused by extending truncate or by
+ * write starting after current i_size. We mark the page straddling current
+ * i_size RO so that page_mkwrite() is called on the nearest write access to
+ * the page.  This way filesystem can be sure that page_mkwrite() is called on
+ * the page before user writes to the page via mmap after the i_size has been
+ * changed.
+ *
+ * The function must be called after i_size is updated so that page fault
+ * coming after we unlock the page will already see the new i_size.
+ * The function must be called while we still hold i_rwsem - this not only
+ * makes sure i_size is stable but also that userspace cannot observe new
+ * i_size value before we are prepared to store mmap writes at new inode size.
+ */
+void pagecache_isize_extended(struct inode *inode, loff_t from, loff_t to)
+{
+	int bsize = i_blocksize(inode);
+	loff_t rounded_from;
+	struct page *page;
+	pgoff_t index;
+
+	WARN_ON(to > inode->i_size);
+
+	if (from >= to || bsize == PAGE_SIZE)
+		return;
+	/* Page straddling @from will not have any hole block created? */
+	rounded_from = round_up(from, bsize);
+	if (to <= rounded_from || !(rounded_from & (PAGE_SIZE - 1)))
+		return;
+
+	index = from >> PAGE_SHIFT;
+	page = find_lock_page(inode->i_mapping, index);
+	/* Page not cached? Nothing to do */
+	if (!page)
+		return;
+	/*
+	 * See clear_page_dirty_for_io() for details why set_page_dirty()
+	 * is needed.
+	 */
+	if (page_mkclean(page))
+		set_page_dirty(page);
+	unlock_page(page);
+	put_page(page);
+}
+EXPORT_SYMBOL(pagecache_isize_extended);
+
+/**
+ * truncate_pagecache_range - unmap and remove pagecache that is hole-punched
+ * @inode: inode
+ * @lstart: offset of beginning of hole
+ * @lend: offset of last byte of hole
+ *
+ * This function should typically be called before the filesystem
+ * releases resources associated with the freed range (eg. deallocates
+ * blocks). This way, pagecache will always stay logically coherent
+ * with on-disk format, and the filesystem would not have to deal with
+ * situations such as writepage being called for a page that has already
+ * had its underlying blocks deallocated.
+ */
+void truncate_pagecache_range(struct inode *inode, loff_t lstart, loff_t lend)
+{
+	struct address_space *mapping = inode->i_mapping;
+	loff_t unmap_start = round_up(lstart, PAGE_SIZE);
+	loff_t unmap_end = round_down(1 + lend, PAGE_SIZE) - 1;
+	/*
+	 * This rounding is currently just for example: unmap_mapping_range
+	 * expands its hole outwards, whereas we want it to contract the hole
+	 * inwards.  However, existing callers of truncate_pagecache_range are
+	 * doing their own page rounding first.  Note that unmap_mapping_range
+	 * allows holelen 0 for all, and we allow lend -1 for end of file.
+	 */
+
+	/*
+	 * Unlike in truncate_pagecache, unmap_mapping_range is called only
+	 * once (before truncating pagecache), and without "even_cows" flag:
+	 * hole-punching should not remove private COWed pages from the hole.
+	 */
+	if ((u64)unmap_end > (u64)unmap_start)
+		unmap_mapping_range(mapping, unmap_start,
+				    1 + unmap_end - unmap_start, 0);
+	truncate_inode_pages_range(mapping, lstart, lend);
+}
+EXPORT_SYMBOL(truncate_pagecache_range);