Date: Sat, 26 Jul 2014 13:56:50 +0000 (UTC) From: Alexander Motin <mav@FreeBSD.org> To: src-committers@freebsd.org, svn-src-all@freebsd.org, svn-src-head@freebsd.org Subject: svn commit: r269123 - head/sys/cam/ctl Message-ID: <201407261356.s6QDuotb033601@svn.freebsd.org>
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Author: mav Date: Sat Jul 26 13:56:50 2014 New Revision: 269123 URL: http://svnweb.freebsd.org/changeset/base/269123 Log: Implement separate I/O dispatch method for ZVOLs in "dev" mode. Unlike disk devices ZVOLs process all requests synchronously. That makes impossible sending multiple requests to them from single thread. From the other side ZVOLs have real d_read/d_write methods, which unlike d_strategy can handle uio scatter/gather and have no strict I/O size limitations. So, if ZVOL in "dev" mode is detected, use of d_read/d_write methods instead of d_strategy allows to avoid pointless splitting of large requests into MAXPHYS (128K) sized chunks. MFC after: 1 week Modified: head/sys/cam/ctl/ctl_backend_block.c Modified: head/sys/cam/ctl/ctl_backend_block.c ============================================================================== --- head/sys/cam/ctl/ctl_backend_block.c Sat Jul 26 13:43:25 2014 (r269122) +++ head/sys/cam/ctl/ctl_backend_block.c Sat Jul 26 13:56:50 2014 (r269123) @@ -738,6 +738,88 @@ ctl_be_block_dispatch_file(struct ctl_be } static void +ctl_be_block_dispatch_zvol(struct ctl_be_block_lun *be_lun, + struct ctl_be_block_io *beio) +{ + struct ctl_be_block_devdata *dev_data; + union ctl_io *io; + struct uio xuio; + struct iovec *xiovec; + int flags; + int error, i; + + DPRINTF("entered\n"); + + dev_data = &be_lun->backend.dev; + io = beio->io; + flags = beio->bio_flags; + + bzero(&xuio, sizeof(xuio)); + if (beio->bio_cmd == BIO_READ) { + SDT_PROBE(cbb, kernel, read, file_start, 0, 0, 0, 0, 0); + xuio.uio_rw = UIO_READ; + } else { + SDT_PROBE(cbb, kernel, write, file_start, 0, 0, 0, 0, 0); + xuio.uio_rw = UIO_WRITE; + } + xuio.uio_offset = beio->io_offset; + xuio.uio_resid = beio->io_len; + xuio.uio_segflg = UIO_SYSSPACE; + xuio.uio_iov = beio->xiovecs; + xuio.uio_iovcnt = beio->num_segs; + xuio.uio_td = curthread; + + for (i = 0, xiovec = xuio.uio_iov; i < xuio.uio_iovcnt; i++, xiovec++) { + xiovec->iov_base = beio->sg_segs[i].addr; + xiovec->iov_len = beio->sg_segs[i].len; + } + + binuptime(&beio->ds_t0); + mtx_lock(&be_lun->io_lock); + devstat_start_transaction(beio->lun->disk_stats, &beio->ds_t0); + mtx_unlock(&be_lun->io_lock); + + if (beio->bio_cmd == BIO_READ) { + error = (*dev_data->csw->d_read)(dev_data->cdev, &xuio, 0); + SDT_PROBE(cbb, kernel, read, file_done, 0, 0, 0, 0, 0); + } else { + error = (*dev_data->csw->d_write)(dev_data->cdev, &xuio, 0); + SDT_PROBE(cbb, kernel, write, file_done, 0, 0, 0, 0, 0); + } + + mtx_lock(&be_lun->io_lock); + devstat_end_transaction(beio->lun->disk_stats, beio->io_len, + beio->ds_tag_type, beio->ds_trans_type, + /*now*/ NULL, /*then*/&beio->ds_t0); + mtx_unlock(&be_lun->io_lock); + + /* + * If we got an error, set the sense data to "MEDIUM ERROR" and + * return the I/O to the user. + */ + if (error != 0) { + ctl_set_medium_error(&io->scsiio); + ctl_complete_beio(beio); + return; + } + + /* + * If this is a write or a verify, we're all done. + * If this is a read, we can now send the data to the user. + */ + if ((beio->bio_cmd == BIO_WRITE) || + (ARGS(io)->flags & CTL_LLF_VERIFY)) { + ctl_set_success(&io->scsiio); + ctl_complete_beio(beio); + } else { +#ifdef CTL_TIME_IO + getbintime(&io->io_hdr.dma_start_bt); +#endif + ctl_datamove(io); + } +} + +static void ctl_be_block_flush_dev(struct ctl_be_block_lun *be_lun, struct ctl_be_block_io *beio) { @@ -1578,14 +1660,17 @@ ctl_be_block_open_dev(struct ctl_be_bloc params = &req->reqdata.create; be_lun->dev_type = CTL_BE_BLOCK_DEV; - be_lun->dispatch = ctl_be_block_dispatch_dev; - be_lun->lun_flush = ctl_be_block_flush_dev; - be_lun->unmap = ctl_be_block_unmap_dev; be_lun->backend.dev.cdev = be_lun->vn->v_rdev; be_lun->backend.dev.csw = dev_refthread(be_lun->backend.dev.cdev, &be_lun->backend.dev.dev_ref); if (be_lun->backend.dev.csw == NULL) panic("Unable to retrieve device switch"); + if (strcmp(be_lun->backend.dev.csw->d_name, "zvol") == 0) + be_lun->dispatch = ctl_be_block_dispatch_zvol; + else + be_lun->dispatch = ctl_be_block_dispatch_dev; + be_lun->lun_flush = ctl_be_block_flush_dev; + be_lun->unmap = ctl_be_block_unmap_dev; error = VOP_GETATTR(be_lun->vn, &vattr, NOCRED); if (error) {
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