filemap: find_get_entries() now updates start offset

Initially, find_get_entries() was being passed in the start offset as a
value.  That left the calculation of the offset to the callers.  This led
to complexity in the callers trying to keep track of the index.

Now find_get_entries() takes in a pointer to the start offset and updates
the value to be directly after the last entry found.  If no entry is
found, the offset is not changed.  This gets rid of multiple hacky
calculations that kept track of the start offset.

Link: https://lkml.kernel.org/r/20221017161800.2003-3-vishal.moola@gmail.com
Signed-off-by: Vishal Moola (Oracle) <vishal.moola@gmail.com>
Cc: Hugh Dickins <hughd@google.com>
Cc: Matthew Wilcox <willy@infradead.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

1 files changed, 7 insertions, 12 deletions

diff --git a/mm/truncate.c b/mm/truncate.c
index b6065a494c71..c7bfd247a651 100644
--- a/mm/truncate.c
+++ b/mm/truncate.c
@@ -400,7 +400,7 @@ void truncate_inode_pages_range(struct address_space *mapping,
 	index = start;
 	while (index < end) {
 		cond_resched();
-		if (!find_get_entries(mapping, index, end - 1, &fbatch,
+		if (!find_get_entries(mapping, &index, end - 1, &fbatch,
 				indices)) {
 			/* If all gone from start onwards, we're done */
 			if (index == start)
@@ -414,21 +414,18 @@ void truncate_inode_pages_range(struct address_space *mapping,
 			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);
+			VM_BUG_ON_FOLIO(!folio_contains(folio, indices[i]), 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);
@@ -636,16 +633,15 @@ int invalidate_inode_pages2_range(struct address_space *mapping,
 
 	folio_batch_init(&fbatch);
 	index = start;
-	while (find_get_entries(mapping, index, end, &fbatch, indices)) {
+	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))
+						indices[i], folio))
 					ret = -EBUSY;
 				continue;
 			}
@@ -655,13 +651,13 @@ int invalidate_inode_pages2_range(struct address_space *mapping,
 				 * 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);
+				unmap_mapping_pages(mapping, indices[i],
+						(1 + end - indices[i]), false);
 				did_range_unmap = 1;
 			}
 
 			folio_lock(folio);
-			VM_BUG_ON_FOLIO(!folio_contains(folio, index), folio);
+			VM_BUG_ON_FOLIO(!folio_contains(folio, indices[i]), folio);
 			if (folio->mapping != mapping) {
 				folio_unlock(folio);
 				continue;
@@ -684,7 +680,6 @@ int invalidate_inode_pages2_range(struct address_space *mapping,
 		folio_batch_remove_exceptionals(&fbatch);
 		folio_batch_release(&fbatch);
 		cond_resched();
-		index++;
 	}
 	/*
 	 * For DAX we invalidate page tables after invalidating page cache.  We