[PATCH] filemap: Fix some misleading comments

[Jiachen Zhang <zhangjiachen.jaycee@bytedance.com>]

The users of filemap_write_and_wait_range() and file_write_and_wait_range()
interfaces should set the lend parameter to LLONG_MAX, rather than -1, to
indicate they want to writeback to the very end-of-file, as several kernel
code paths are checking the 'wbc->range_end == LLONG_MAX' conditions.

Signed-off-by: Jiachen Zhang <zhangjiachen.jaycee@bytedance.com>
---
 mm/filemap.c | 6 ++++--
 1 file changed, 4 insertions(+), 2 deletions(-)

diff --git a/mm/filemap.c b/mm/filemap.c
index 65eee6ec1066..c6d066a39425 100644
--- a/mm/filemap.c
+++ b/mm/filemap.c
@@ -661,7 +661,8 @@ EXPORT_SYMBOL_GPL(filemap_range_has_writeback);
  * Write out and wait upon file offsets lstart->lend, inclusive.
  *
  * Note that @lend is inclusive (describes the last byte to be written) so
- * that this function can be used to write to the very end-of-file (end = -1).
+ * that this function can be used to write to the very end-of-file (@lend =
+ * LLONG_MAX).
  *
  * Return: error status of the address space.
  */
@@ -758,7 +759,8 @@ EXPORT_SYMBOL(file_check_and_advance_wb_err);
  * Write out and wait upon file offsets lstart->lend, inclusive.
  *
  * Note that @lend is inclusive (describes the last byte to be written) so
- * that this function can be used to write to the very end-of-file (end = -1).
+ * that this function can be used to write to the very end-of-file (@lend =
+ * LLONG_MAX).
  *
  * After writing out and waiting on the data, we check and advance the
  * f_wb_err cursor to the latest value, and return any errors detected there.
-- 
2.20.1