From 6450fe1f668f410fe2ab69c79a52a0929a4a8296 Mon Sep 17 00:00:00 2001 From: Pavel Begunkov Date: Wed, 20 Oct 2021 20:00:48 +0100 Subject: block: optimise boundary blkdev_read_iter's checks Combine pos and len checks and mark unlikely. Also, don't reexpand if it's not truncated. Reviewed-by: Christoph Hellwig Signed-off-by: Pavel Begunkov Link: https://lore.kernel.org/r/fff34e613aeaae1ad12977dc4592cb1a1f5d3190.1634755800.git.asml.silence@gmail.com Signed-off-by: Jens Axboe --- block/fops.c | 19 +++++++++++-------- 1 file changed, 11 insertions(+), 8 deletions(-) (limited to 'block/fops.c') diff --git a/block/fops.c b/block/fops.c index 21d25ee0e4bf..8f733c919ed1 100644 --- a/block/fops.c +++ b/block/fops.c @@ -503,17 +503,20 @@ static ssize_t blkdev_read_iter(struct kiocb *iocb, struct iov_iter *to) size_t shorted = 0; ssize_t ret; - if (pos >= size) - return 0; - - size -= pos; - if (iov_iter_count(to) > size) { - shorted = iov_iter_count(to) - size; - iov_iter_truncate(to, size); + if (unlikely(pos + iov_iter_count(to) > size)) { + if (pos >= size) + return 0; + size -= pos; + if (iov_iter_count(to) > size) { + shorted = iov_iter_count(to) - size; + iov_iter_truncate(to, size); + } } ret = generic_file_read_iter(iocb, to); - iov_iter_reexpand(to, iov_iter_count(to) + shorted); + + if (unlikely(shorted)) + iov_iter_reexpand(to, iov_iter_count(to) + shorted); return ret; } -- cgit v1.2.3