From: Ming Lei Date: Mon, 17 Aug 2015 02:31:46 +0000 (+0800) Subject: fs: direct-io: don't dirtying pages for ITER_BVEC/ITER_KVEC direct read X-Git-Url: https://git.karo-electronics.de/?a=commitdiff_plain;h=53cbf3b157a0428d40989ab1c7df9228a1976fc2;p=linux-beck.git fs: direct-io: don't dirtying pages for ITER_BVEC/ITER_KVEC direct read When direct read IO is submitted from kernel, it is often unnecessary to dirty pages, for example of loop, dirtying pages have been considered in the upper filesystem(over loop) side already, and they don't need to be dirtied again. So this patch doesn't dirtying pages for ITER_BVEC/ITER_KVEC direct read, and loop should be the 1st case to use ITER_BVEC/ITER_KVEC for direct read I/O. The patch is based on previous Dave's patch. Reviewed-by: Dave Kleikamp Reviewed-by: Christoph Hellwig Signed-off-by: Ming Lei Signed-off-by: Jens Axboe --- diff --git a/fs/direct-io.c b/fs/direct-io.c index 11256291642e..3ae0e0427191 100644 --- a/fs/direct-io.c +++ b/fs/direct-io.c @@ -120,6 +120,7 @@ struct dio { int page_errors; /* errno from get_user_pages() */ int is_async; /* is IO async ? */ bool defer_completion; /* defer AIO completion to workqueue? */ + bool should_dirty; /* if pages should be dirtied */ int io_error; /* IO error in completion path */ unsigned long refcount; /* direct_io_worker() and bios */ struct bio *bio_list; /* singly linked via bi_private */ @@ -393,7 +394,7 @@ static inline void dio_bio_submit(struct dio *dio, struct dio_submit *sdio) dio->refcount++; spin_unlock_irqrestore(&dio->bio_lock, flags); - if (dio->is_async && dio->rw == READ) + if (dio->is_async && dio->rw == READ && dio->should_dirty) bio_set_pages_dirty(bio); if (sdio->submit_io) @@ -464,14 +465,15 @@ static int dio_bio_complete(struct dio *dio, struct bio *bio) if (bio->bi_error) dio->io_error = -EIO; - if (dio->is_async && dio->rw == READ) { + if (dio->is_async && dio->rw == READ && dio->should_dirty) { bio_check_pages_dirty(bio); /* transfers ownership */ err = bio->bi_error; } else { bio_for_each_segment_all(bvec, bio, i) { struct page *page = bvec->bv_page; - if (dio->rw == READ && !PageCompound(page)) + if (dio->rw == READ && !PageCompound(page) && + dio->should_dirty) set_page_dirty_lock(page); page_cache_release(page); } @@ -1219,6 +1221,7 @@ do_blockdev_direct_IO(struct kiocb *iocb, struct inode *inode, spin_lock_init(&dio->bio_lock); dio->refcount = 1; + dio->should_dirty = (iter->type == ITER_IOVEC); sdio.iter = iter; sdio.final_block_in_request = (offset + iov_iter_count(iter)) >> blkbits;