On Fri, 25 Nov 2022 15:09:59 +0800 Jiachen Zhang <zhangjiachen.jaycee@xxxxxxxxxxxxx> wrote: > 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. Unclear. LLONG_MAX differs from -1 on 64-bit and differs differently on 32-bit. > --- 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). > * The write(2) manpage says "According to POSIX.1, if count is greater than SSIZE_MAX, the result is implementation-defined; see NOTES for the upper limit on Linux." And filemap_fdatawrite_wbc() enforces LONG_MAX, which differs from LLONG_MAX on 32-bit. I suspect more research is needed here.
