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block: move direct_IO into our own read_iter handler
Don't call into generic_file_read_iter() if we know it's O_DIRECT, just set it up ourselves and call our own handler. This avoids an indirect call for O_DIRECT. Fall back to filemap_read() if we fail. Signed-off-by: Jens Axboe <axboe@kernel.dk>
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parent
4bdcd1dd4d
commit
ceaa762527
1 changed files with 32 additions and 5 deletions
37
block/fops.c
37
block/fops.c
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@ -566,21 +566,48 @@ static ssize_t blkdev_read_iter(struct kiocb *iocb, struct iov_iter *to)
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{
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{
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struct block_device *bdev = iocb->ki_filp->private_data;
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struct block_device *bdev = iocb->ki_filp->private_data;
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loff_t size = bdev_nr_bytes(bdev);
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loff_t size = bdev_nr_bytes(bdev);
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size_t count = iov_iter_count(to);
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loff_t pos = iocb->ki_pos;
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loff_t pos = iocb->ki_pos;
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size_t shorted = 0;
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size_t shorted = 0;
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ssize_t ret;
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ssize_t ret = 0;
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if (unlikely(pos + iov_iter_count(to) > size)) {
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if (unlikely(pos + count > size)) {
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if (pos >= size)
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if (pos >= size)
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return 0;
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return 0;
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size -= pos;
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size -= pos;
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if (iov_iter_count(to) > size) {
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if (count > size) {
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shorted = iov_iter_count(to) - size;
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shorted = count - size;
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iov_iter_truncate(to, size);
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iov_iter_truncate(to, size);
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}
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}
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}
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}
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ret = generic_file_read_iter(iocb, to);
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if (iocb->ki_flags & IOCB_DIRECT) {
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struct address_space *mapping = iocb->ki_filp->f_mapping;
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if (iocb->ki_flags & IOCB_NOWAIT) {
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if (filemap_range_needs_writeback(mapping, iocb->ki_pos,
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iocb->ki_pos + count - 1))
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return -EAGAIN;
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} else {
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ret = filemap_write_and_wait_range(mapping,
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iocb->ki_pos,
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iocb->ki_pos + count - 1);
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if (ret < 0)
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return ret;
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}
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file_accessed(iocb->ki_filp);
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ret = blkdev_direct_IO(iocb, to);
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if (ret >= 0) {
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iocb->ki_pos += ret;
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count -= ret;
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}
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if (ret < 0 || !count)
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return ret;
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}
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ret = filemap_read(iocb, to, ret);
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if (unlikely(shorted))
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if (unlikely(shorted))
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iov_iter_reexpand(to, iov_iter_count(to) + shorted);
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iov_iter_reexpand(to, iov_iter_count(to) + shorted);
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