On 4/12/17 12:30 AM, Nicholas A. Bellinger wrote:
> On Mon, 2017-04-10 at 18:08 +0200, Christoph Hellwig wrote:
>> Use the pscsi driver to support arbitrary command passthrough
>> instead.
>>
> The people who are actively using iblock_execute_write_same_direct() are
> doing so in the context of ESX VAAI BlockZero, together with
> EXTENDED_COPY and COMPARE_AND_WRITE primitives. Just using PSCSI is not
> an option for them.
>
> In practice though I've not seen any users of IBLOCK WRITE_SAME for
> anything other than VAAI BlockZero, so just using blkdev_issue_zeroout()
> when available, and falling back to iblock_execute_write_same() if the
> WRITE_SAME buffer contains anything other than zeros should be OK.
>
> How about something like the following below..?
>
> This would bring parity to how blkdev_issue_write_same() works atm wrt
> to synchronous bio completions. However, most folks with a raw
> make_request or blk-mq backend driver that supports multiple GB/sec of
> zero bandwidth end up changing IBLOCK to support asynchronous
> REQ_WRITE_SAME completions anyways.
>
> I'd be happy to add support for that using __blkdev_issue_zeroout() once
> the basic conversion is in place.
>
> From ff74012eaff38f9fa0d74aca60507b9964f484ce Mon Sep 17 00:00:00 2001
> From: Nicholas Bellinger <nab@xxxxxxxxxxxxxxx>
> Date: Tue, 11 Apr 2017 22:21:47 -0700
> Subject: [PATCH] target/iblock: Convert WRITE_SAME to blkdev_issue_zeroout
>
> Signed-off-by: Nicholas Bellinger <nab@xxxxxxxxxxxxxxx>
> ---
> drivers/target/target_core_iblock.c | 44 +++++++++++++++++++++++--------------
> 1 file changed, 27 insertions(+), 17 deletions(-)
>
> diff --git a/drivers/target/target_core_iblock.c b/drivers/target/target_core_iblock.c
> index d316ed5..5bfde20 100644
> --- a/drivers/target/target_core_iblock.c
> +++ b/drivers/target/target_core_iblock.c
> @@ -86,6 +86,7 @@ static int iblock_configure_device(struct se_device *dev)
> struct block_device *bd = NULL;
> struct blk_integrity *bi;
> fmode_t mode;
> + unsigned int max_write_zeroes_sectors;
> int ret = -ENOMEM;
>
> if (!(ib_dev->ibd_flags & IBDF_HAS_UDEV_PATH)) {
> @@ -129,7 +130,11 @@ static int iblock_configure_device(struct se_device *dev)
> * Enable write same emulation for IBLOCK and use 0xFFFF as
> * the smaller WRITE_SAME(10) only has a two-byte block count.
> */
> - dev->dev_attrib.max_write_same_len = 0xFFFF;
> + max_write_zeroes_sectors = bdev_write_zeroes_sectors(bd);
> + if (max_write_zeroes_sectors)
> + dev->dev_attrib.max_write_same_len = max_write_zeroes_sectors;
> + else
> + dev->dev_attrib.max_write_same_len = 0xFFFF;
>
> if (blk_queue_nonrot(q))
> dev->dev_attrib.is_nonrot = 1;
> @@ -415,28 +420,31 @@ static void iblock_end_io_flush(struct bio *bio)
> }
>
> static sense_reason_t
> -iblock_execute_write_same_direct(struct block_device *bdev, struct se_cmd *cmd)
> +iblock_execute_zero_out(struct block_device *bdev, struct se_cmd *cmd)
> {
> struct se_device *dev = cmd->se_dev;
> struct scatterlist *sg = &cmd->t_data_sg[0];
> - struct page *page = NULL;
> - int ret;
> + unsigned char *buf, zero = 0x00, *p = &zero;
> + int rc, ret;
>
> - if (sg->offset) {
> - page = alloc_page(GFP_KERNEL);
> - if (!page)
> - return TCM_OUT_OF_RESOURCES;
> - sg_copy_to_buffer(sg, cmd->t_data_nents, page_address(page),
> - dev->dev_attrib.block_size);
> - }
> + buf = kmap(sg_page(sg)) + sg->offset;
> + if (!buf)
> + return TCM_LOGICAL_UNIT_COMMUNICATION_FAILURE;
> + /*
> + * Fall back to block_execute_write_same() slow-path if
> + * incoming WRITE_SAME payload does not contain zeros.
> + */
> + rc = memcmp(buf, p, cmd->data_length);
> + kunmap(sg_page(sg));
> +
I recently pulled in this patch and I am getting:
[ 716.756756] ------------[ cut here ]------------
[ 716.756757] kernel BUG at /build/linux-hwe-edge-F6_Smd/linux-hwe-edge-4.13.0/lib/string.c:985!
[ 716.756762] Oops: Exception in kernel mode, sig: 5 [#1]
[ 716.756764] SMP NR_CPUS=2048
[ 716.756765] NUMA
[ 716.756767] pSeries
[ 716.756769] Modules linked in: hvcs(OE) hvcserver dm_snapshot dm_bufio ip6table_raw xt_CT xt_mac xt_tcpudp xt_comment xt_physdev xt_set ip_set_hash_net ip_set rpadlpar_io rpaphp iptable_raw target_core_pscsi(OE) target_core_file(OE) target_core_iblock(OE) iscsi_target_mod(OE) dccp_diag dccp tcp_diag udp_diag inet_diag unix_diag af_packet_diag netlink_diag vport_vxlan vxlan ip6_udp_tunnel udp_tunnel openvswitch nf_nat_ipv6 target_core_user(OE) uio binfmt_misc ibmvmc(OE) pseries_rng vmx_crypto crct10dif_vpmsum xt_conntrack nf_nat_ftp nf_conntrack_ftp nf_conntrack_netlink nfnetlink nf_conntrack_netbios_ns nf_conntrack_broadcast nf_conntrack_ipv6 nf_defrag_ipv6 nbd ipt_REJECT nf_reject_ipv4 ipt_MASQUERADE nf_nat_masquerade_ipv4 iptable_nat nf_conntrack_ipv4 nf_defrag_ipv4 nf_nat_ipv4 nf_nat nf_conntrack
[ 716.756825] iptable_mangle iptable_filter ip_tables ip6table_filter ip6_tables ebtables x_tables br_netfilter bridge stp llc ib_iser rdma_cm iw_cm ib_cm ib_core iscsi_tcp libiscsi_tcp libiscsi scsi_transport_iscsi autofs4 btrfs raid10 raid456 async_raid6_recov async_memcpy async_pq async_xor async_tx xor raid6_pq raid1 raid0 multipath linear mlx4_en dm_round_robin ses enclosure scsi_transport_sas ibmvscsis(OE) target_core_mod(OE) ibmveth(OE) mlx5_core mlx4_core bnx2x mdio libcrc32c crc32c_vpmsum mlxfw ipr devlink tg3 scsi_dh_emc scsi_dh_rdac scsi_dh_alua dm_multipath
[ 716.756872] CPU: 1 PID: 3685 Comm: kworker/1:2 Tainted: G OE 4.13.0-16-generic #19~16.04.3-Ubuntu
[ 716.756880] Workqueue: ibmvscsis30000008 ibmvscsis_scheduler [ibmvscsis]
[ 716.756883] task: c0000001ee076a00 task.stack: c0000001b536c000
[ 716.756885] NIP: c000000000c26620 LR: c000000000c2661c CTR: 0000000000655170
[ 716.756888] REGS: c0000001b536f590 TRAP: 0700 Tainted: G OE (4.13.0-16-generic)
[ 716.756891] MSR: 800000000282b033 <SF,VEC,VSX,EE,FP,ME,IR,DR,RI,LE>
[ 716.756896] CR: 28482222 XER: 20000003
[ 716.756899] CFAR: c000000000179740 SOFTE: 1
GPR00: c000000000c2661c c0000001b536f810 c0000000015c2b00 0000000000000022
GPR04: c0000001f704ade8 c0000001f7062068 0000000000000003 ffffffffffffffff
GPR08: 0000000000000007 c0000000010d1a74 00000001f5f80000 0000000000000066
GPR12: 0000000000002200 c00000000fac0a80 c000000000129158 c0000001f2b5bb00
GPR16: 0000000000000000 0000000000000000 0000000000000000 0000000000000000
GPR20: 0000000000000000 0000000000000000 0000000000000000 fffffffffffffef7
GPR24: 0000000000000000 f0000000007a82c0 00000000000003f0 0000000000648010
GPR28: c00000004394fbd0 c0000001f36c2780 c0000001ddb0e700 c0000001e391a000
[ 716.756932] NIP [c000000000c26620] fortify_panic+0x28/0x38
[ 716.756935] LR [c000000000c2661c] fortify_panic+0x24/0x38
[ 716.756937] Call Trace:
[ 716.756939] [c0000001b536f810] [c000000000c2661c] fortify_panic+0x24/0x38 (unreliable)
[ 716.756944] [c0000001b536f870] [d000000013c30bf8] iblock_execute_write_same+0x3b8/0x3c0 [target_core_iblock]
[ 716.756955] [c0000001b536f920] [d00000000b6537b4] __target_execute_cmd+0x54/0x150 [target_core_mod]
[ 716.756960] [c0000001b536f950] [d00000000b822c90] ibmvscsis_write_pending+0x70/0xc0 [ibmvscsis]
[ 716.756969] [c0000001b536f9c0] [d00000000b654f28] transport_generic_new_cmd+0x318/0x370 [target_core_mod]
[ 716.756979] [c0000001b536fa40] [d00000000b654fe4] transport_handle_cdb_direct+0x64/0xd0 [target_core_mod]
[ 716.756988] [c0000001b536fab0] [d00000000b6551f8] target_submit_cmd_map_sgls+0x1a8/0x320 [target_core_mod]
[ 716.756998] [c0000001b536fb40] [d00000000b6553b8] target_submit_cmd+0x48/0x60 [target_core_mod]
[ 716.757002] [c0000001b536fbe0] [d00000000b824bb0] ibmvscsis_scheduler+0x370/0x600 [ibmvscsis]
[ 716.757007] [c0000001b536fca0] [c0000000001200fc] process_one_work+0x1ec/0x580
[ 716.757010] [c0000001b536fd30] [c000000000120528] worker_thread+0x98/0x5d0
[ 716.757013] [c0000001b536fdc0] [c0000000001292bc] kthread+0x16c/0x1b0
[ 716.757017] [c0000001b536fe30] [c00000000000b4e8] ret_from_kernel_thread+0x5c/0x74
[ 716.757020] Instruction dump:
[ 716.757022] 7c0803a6 4e800020 3c4c009a 3842c508 7c0802a6 f8010010 f821ffa1 7c641b78
[ 716.757027] 3c62ff98 3863e8b8 4b5530dd 60000000 <0fe00000> 00000000 00000000 00000000
[ 716.757033] ---[ end trace 1f1264fedf09f0b7 ]---
It looks like memcmp is throwing the fortify panic due to size of ptrs being incorrectly
determined at compile time.
-Bryant
