[PATCH AUTOSEL 6.12 18/20] iomap: avoid avoid truncating 64-bit offset to 32 bits

[Sasha Levin]

From: Marco Nelissen <marco.nelissen@xxxxxxxxx>

[ Upstream commit c13094b894de289514d84b8db56d1f2931a0bade ]

on 32-bit kernels, iomap_write_delalloc_scan() was inadvertently using a
32-bit position due to folio_next_index() returning an unsigned long.
This could lead to an infinite loop when writing to an xfs filesystem.

Signed-off-by: Marco Nelissen <marco.nelissen@xxxxxxxxx>
Link: https://lore.kernel.org/r/20250109041253.2494374-1-marco.nelissen@xxxxxxxxx
Reviewed-by: Darrick J. Wong <djwong@xxxxxxxxxx>
Reviewed-by: Christoph Hellwig <hch@xxxxxx>
Signed-off-by: Christian Brauner <brauner@xxxxxxxxxx>
Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>
---
 fs/iomap/buffered-io.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/fs/iomap/buffered-io.c b/fs/iomap/buffered-io.c
index 3ffd9937dd51..49da74539fb3 100644
--- a/fs/iomap/buffered-io.c
+++ b/fs/iomap/buffered-io.c
@@ -1138,7 +1138,7 @@ static void iomap_write_delalloc_scan(struct inode *inode,
 				start_byte, end_byte, iomap, punch);
 
 		/* move offset to start of next folio in range */
-		start_byte = folio_next_index(folio) << PAGE_SHIFT;
+		start_byte = folio_pos(folio) + folio_size(folio);
 		folio_unlock(folio);
 		folio_put(folio);
 	}
-- 
2.39.5