From: Jens Axboe <axboe@xxxxxxxxx> Subject: iomap: use filemap_range_needs_writeback() for O_DIRECT reads For reads, use the better variant of checking for the need to call filemap_write_and_wait_range() when doing O_DIRECT. This avoids falling back to the slow path for IOCB_NOWAIT, if there are no pages to wait for (or write out). Link: https://lkml.kernel.org/r/20210224164455.1096727-4-axboe@xxxxxxxxx Signed-off-by: Jens Axboe <axboe@xxxxxxxxx> Reviewed-by: Jan Kara <jack@xxxxxxx> Cc: Matthew Wilcox (Oracle) <willy@xxxxxxxxxxxxx> Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx> --- fs/iomap/direct-io.c | 24 ++++++++++++++++-------- 1 file changed, 16 insertions(+), 8 deletions(-) --- a/fs/iomap/direct-io.c~iomap-use-filemap_range_needs_writeback-for-o_direct-reads +++ a/fs/iomap/direct-io.c @@ -487,12 +487,28 @@ __iomap_dio_rw(struct kiocb *iocb, struc if (pos >= dio->i_size) goto out_free_dio; + if (iocb->ki_flags & IOCB_NOWAIT) { + if (filemap_range_needs_writeback(mapping, pos, end)) { + ret = -EAGAIN; + goto out_free_dio; + } + iomap_flags |= IOMAP_NOWAIT; + } + if (iter_is_iovec(iter)) dio->flags |= IOMAP_DIO_DIRTY; } else { iomap_flags |= IOMAP_WRITE; dio->flags |= IOMAP_DIO_WRITE; + if (iocb->ki_flags & IOCB_NOWAIT) { + if (filemap_range_has_page(mapping, pos, end)) { + ret = -EAGAIN; + goto out_free_dio; + } + iomap_flags |= IOMAP_NOWAIT; + } + /* for data sync or sync, we need sync completion processing */ if (iocb->ki_flags & IOCB_DSYNC) dio->flags |= IOMAP_DIO_NEED_SYNC; @@ -507,14 +523,6 @@ __iomap_dio_rw(struct kiocb *iocb, struc dio->flags |= IOMAP_DIO_WRITE_FUA; } - if (iocb->ki_flags & IOCB_NOWAIT) { - if (filemap_range_has_page(mapping, pos, end)) { - ret = -EAGAIN; - goto out_free_dio; - } - iomap_flags |= IOMAP_NOWAIT; - } - if (dio_flags & IOMAP_DIO_OVERWRITE_ONLY) { ret = -EAGAIN; if (pos >= dio->i_size || pos + count > dio->i_size) _
