On Thu, Jul 20, 2023 at 04:04:52PM +0200, Christoph Hellwig wrote: > @@ -400,7 +391,8 @@ static int blkdev_iomap_begin(struct inode *inode, loff_t offset, loff_t length, > iomap->type = IOMAP_MAPPED; > iomap->addr = iomap->offset; > iomap->length = isize - iomap->offset; > - iomap->flags |= IOMAP_F_BUFFER_HEAD; > + if (IS_ENABLED(CONFIG_BUFFER_HEAD)) > + iomap->flags |= IOMAP_F_BUFFER_HEAD; Wouldn't it be simpler to do ... +#ifdef CONFIG_BUFFER_HEAD #define IOMAP_F_BUFFER_HEAD (1U << 4) +#else +#define IOMAP_F_BUFFER_HEAD 0 +#endif in include/linux/iomap.h ? > diff --git a/fs/iomap/buffered-io.c b/fs/iomap/buffered-io.c > index 0607790827b48a..6dc585c010c020 100644 > --- a/fs/iomap/buffered-io.c > +++ b/fs/iomap/buffered-io.c > @@ -41,6 +41,12 @@ static inline struct iomap_page *to_iomap_page(struct folio *folio) > return NULL; > } > > +static inline bool iomap_use_buffer_heads(const struct iomap *iomap) > +{ > + return IS_ENABLED(CONFIG_BUFFER_HEAD) && > + (iomap->flags & IOMAP_F_BUFFER_HEAD); > +} ... because this function then goes away. > @@ -675,7 +681,7 @@ static int iomap_write_begin(struct iomap_iter *iter, loff_t pos, > > if (srcmap->type == IOMAP_INLINE) > status = iomap_write_begin_inline(iter, folio); > - else if (srcmap->flags & IOMAP_F_BUFFER_HEAD) > + else if (iomap_use_buffer_heads(srcmap)) ... as this will be optimised away.