1 files changed, 73 insertions, 3 deletions

diff --git a/mm/filemap.c b/mm/filemap.c
index 7437b2bd75c1..1d6b3a369077 100644
--- a/mm/filemap.c
+++ b/mm/filemap.c
@@ -1540,7 +1540,7 @@ EXPORT_SYMBOL(folio_end_private_2);
  * folio_wait_private_2 - Wait for PG_private_2 to be cleared on a folio.
  * @folio: The folio to wait on.
  *
- * Wait for PG_private_2 (aka PG_fscache) to be cleared on a folio.
+ * Wait for PG_private_2 to be cleared on a folio.
  */
 void folio_wait_private_2(struct folio *folio)
 {
@@ -1553,8 +1553,8 @@ EXPORT_SYMBOL(folio_wait_private_2);
  * folio_wait_private_2_killable - Wait for PG_private_2 to be cleared on a folio.
  * @folio: The folio to wait on.
  *
- * Wait for PG_private_2 (aka PG_fscache) to be cleared on a folio or until a
- * fatal signal is received by the calling task.
+ * Wait for PG_private_2 to be cleared on a folio or until a fatal signal is
+ * received by the calling task.
  *
  * Return:
  * - 0 if successful.
@@ -4134,6 +4134,60 @@ bool filemap_release_folio(struct folio *folio, gfp_t gfp)
 }
 EXPORT_SYMBOL(filemap_release_folio);
 
+/**
+ * filemap_invalidate_inode - Invalidate/forcibly write back a range of an inode's pagecache
+ * @inode: The inode to flush
+ * @flush: Set to write back rather than simply invalidate.
+ * @start: First byte to in range.
+ * @end: Last byte in range (inclusive), or LLONG_MAX for everything from start
+ *       onwards.
+ *
+ * Invalidate all the folios on an inode that contribute to the specified
+ * range, possibly writing them back first.  Whilst the operation is
+ * undertaken, the invalidate lock is held to prevent new folios from being
+ * installed.
+ */
+int filemap_invalidate_inode(struct inode *inode, bool flush,
+			     loff_t start, loff_t end)
+{
+	struct address_space *mapping = inode->i_mapping;
+	pgoff_t first = start >> PAGE_SHIFT;
+	pgoff_t last = end >> PAGE_SHIFT;
+	pgoff_t nr = end == LLONG_MAX ? ULONG_MAX : last - first + 1;
+
+	if (!mapping || !mapping->nrpages || end < start)
+		goto out;
+
+	/* Prevent new folios from being added to the inode. */
+	filemap_invalidate_lock(mapping);
+
+	if (!mapping->nrpages)
+		goto unlock;
+
+	unmap_mapping_pages(mapping, first, nr, false);
+
+	/* Write back the data if we're asked to. */
+	if (flush) {
+		struct writeback_control wbc = {
+			.sync_mode	= WB_SYNC_ALL,
+			.nr_to_write	= LONG_MAX,
+			.range_start	= start,
+			.range_end	= end,
+		};
+
+		filemap_fdatawrite_wbc(mapping, &wbc);
+	}
+
+	/* Wait for writeback to complete on all folios and discard. */
+	truncate_inode_pages_range(mapping, start, end);
+
+unlock:
+	filemap_invalidate_unlock(mapping);
+out:
+	return filemap_check_errors(mapping);
+}
+EXPORT_SYMBOL_GPL(filemap_invalidate_inode);
+
 #ifdef CONFIG_CACHESTAT_SYSCALL
 /**
  * filemap_cachestat() - compute the page cache statistics of a mapping
@@ -4197,7 +4251,23 @@ static void filemap_cachestat(struct address_space *mapping,
 				/* shmem file - in swap cache */
 				swp_entry_t swp = radix_to_swp_entry(folio);
 
+				/* swapin error results in poisoned entry */
+				if (non_swap_entry(swp))
+					goto resched;
+
+				/*
+				 * Getting a swap entry from the shmem
+				 * inode means we beat
+				 * shmem_unuse(). rcu_read_lock()
+				 * ensures swapoff waits for us before
+				 * freeing the swapper space. However,
+				 * we can race with swapping and
+				 * invalidation, so there might not be
+				 * a shadow in the swapcache (yet).
+				 */
 				shadow = get_shadow_from_swap_cache(swp);
+				if (!shadow)
+					goto resched;
 			}
 #endif
 			if (workingset_test_recent(shadow, true, &workingset))