Re: first bad commit: [5795eb443060148796beeba106e4366d7f1458a6] scsi: sd_zbc: emulate ZONE_APPEND commands

[Damien Le Moal <Damien.LeMoal@wdc.com>]

On 2020/09/12 8:07, Borislav Petkov wrote:
> On Sat, Sep 12, 2020 at 12:17:59AM +0200, Borislav Petkov wrote:
>> Enabling it, fixes the issue.
> 
> Btw, I just hit the below warn with 5.8, while booting with the above
> config option enabled. Looks familiar and I didn't trigger it with
> 5.9-rc4+ so you guys either fixed it or something changed in-between:
> 
> [    5.124321] ata4.00: NCQ Send/Recv Log not supported
> [    5.131484] ata4.00: configured for UDMA/133
> [    5.135847] scsi 3:0:0:0: Direct-Access     ATA      ST8000AS0022-1WL SN01 PQ: 0 ANSI: 5
> [    5.143972] sd 3:0:0:0: Attached scsi generic sg1 type 0
> [    5.144033] sd 3:0:0:0: [sdb] Host-aware zoned block device
> [    5.177105] sd 3:0:0:0: [sdb] 15628053168 512-byte logical blocks: (8.00 TB/7.28 TiB)
> [    5.184880] sd 3:0:0:0: [sdb] 4096-byte physical blocks
> [    5.190084] sd 3:0:0:0: [sdb] 29808 zones of 524288 logical blocks + 1 runt zone
> [    5.197439] sd 3:0:0:0: [sdb] Write Protect is off
> [    5.202220] sd 3:0:0:0: [sdb] Mode Sense: 00 3a 00 00
> [    5.207260] sd 3:0:0:0: [sdb] Write cache: enabled, read cache: enabled, doesn't support DPO or FUA
> [    5.356631]  sdb: sdb1
> [    5.359014] sdb: disabling host aware zoned block device support due to partitions
> [    5.389941] ------------[ cut here ]------------
> [    5.394557] WARNING: CPU: 8 PID: 164 at block/blk-settings.c:236 blk_queue_max_zone_append_sectors+0x12/0x40
> [    5.404300] Modules linked in:
> [    5.407365] CPU: 8 PID: 164 Comm: kworker/u32:6 Not tainted 5.8.0 #7
> [    5.413682] Hardware name: Micro-Star International Co., Ltd. MS-7B79/X470 GAMING PRO (MS-7B79), BIOS 1.70 01/23/2019
> [    5.424191] Workqueue: events_unbound async_run_entry_fn
> [    5.429482] RIP: 0010:blk_queue_max_zone_append_sectors+0x12/0x40
> [    5.435543] Code: fe 0f 00 00 53 48 89 fb 0f 86 3d 07 00 00 48 89 b3 e0 03 00 00 5b c3 90 0f 1f 44 00 00 8b 87 40 04 00 00 ff c8 83 f8 01 76 03 <0f> 0b c3 8b 87 f8 03 00 00 39 87 f0 03 00 00 0f 46 87 f0 03 00 00
> [    5.454099] RSP: 0018:ffffc90000697c60 EFLAGS: 00010282
> [    5.459306] RAX: 00000000ffffffff RBX: ffff8887fa0a9400 RCX: 0000000000000000
> [    5.466390] RDX: ffff8887faf0d400 RSI: 0000000000000540 RDI: ffff8887f0dde6c8
> [    5.473474] RBP: 0000000000007471 R08: 00000000001d1c40 R09: ffff8887fee29ad0
> [    5.480559] R10: 00000001434bac00 R11: 0000000000358275 R12: 0000000000080000
> [    5.487643] R13: ffff8887f0dde6c8 R14: ffff8887fa0a9738 R15: 0000000000000000
> [    5.494726] FS:  0000000000000000(0000) GS:ffff8887fee00000(0000) knlGS:0000000000000000
> [    5.502757] CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
> [    5.508474] CR2: 0000000000000000 CR3: 0000000002209000 CR4: 00000000003406e0
> [    5.515558] Call Trace:
> [    5.518026]  sd_zbc_read_zones+0x323/0x480
> [    5.522122]  sd_revalidate_disk+0x122b/0x2000
> [    5.526472]  ? __device_add_disk+0x2f7/0x4e0
> [    5.530738]  sd_probe+0x347/0x44b
> [    5.534058]  really_probe+0x2c4/0x3f0
> [    5.537720]  driver_probe_device+0xe1/0x150
> [    5.541902]  ? driver_allows_async_probing+0x50/0x50
> [    5.546852]  bus_for_each_drv+0x6a/0xa0
> [    5.550683]  __device_attach_async_helper+0x8c/0xd0
> [    5.555547]  async_run_entry_fn+0x4a/0x180
> [    5.559636]  process_one_work+0x1a5/0x3a0
> [    5.563637]  worker_thread+0x50/0x3a0
> [    5.567300]  ? process_one_work+0x3a0/0x3a0
> [    5.571480]  kthread+0x117/0x160
> [    5.574715]  ? kthread_park+0x90/0x90
> [    5.578377]  ret_from_fork+0x22/0x30
> [    5.581960] ---[ end trace 94141003236730cf ]---
> [    5.586578] sd 3:0:0:0: [sdb] Attached SCSI disk
> [    6.186783] ata5: failed to resume link (SControl 0)
> [    6.191818] ata5: SATA link down (SStatus 0 SControl 0)
> 

Can you try this:

diff --git a/drivers/scsi/sd.c b/drivers/scsi/sd.c
index 95018e650f2d..620539162ef1 100644
--- a/drivers/scsi/sd.c
+++ b/drivers/scsi/sd.c
@@ -2968,8 +2968,13 @@ static void sd_read_block_characteristics(struct
scsi_disk *sdkp)
        } else {
                sdkp->zoned = (buffer[8] >> 4) & 3;
                if (sdkp->zoned == 1 && !disk_has_partitions(sdkp->disk)) {
+#ifdef CONFIG_BLK_DEV_ZONED
                        /* Host-aware */
                        q->limits.zoned = BLK_ZONED_HA;
+#else
+                       /* Host-aware drive is treated as a regular disk */
+                       q->limits.zoned = BLK_ZONED_NONE;
+#endif
                } else {
                        /*
                         * Treat drive-managed devices and host-aware devices
@@ -3404,12 +3409,12 @@ static int sd_probe(struct device *dev)
        sdkp->first_scan = 1;
        sdkp->max_medium_access_timeouts = SD_MAX_MEDIUM_TIMEOUTS;

+       sd_revalidate_disk(gd);
+
        error = sd_zbc_init_disk(sdkp);
        if (error)
                goto out_free_index;

-       sd_revalidate_disk(gd);
-
        gd->flags = GENHD_FL_EXT_DEVT;
        if (sdp->removable) {
                gd->flags |= GENHD_FL_REMOVABLE;
diff --git a/drivers/scsi/sd.h b/drivers/scsi/sd.h
index 4933e7daf17d..f4dc81d48a01 100644
--- a/drivers/scsi/sd.h
+++ b/drivers/scsi/sd.h
@@ -241,6 +241,8 @@ static inline void sd_zbc_release_disk(struct scsi_disk
*sdkp) {}
 static inline int sd_zbc_read_zones(struct scsi_disk *sdkp,
                                    unsigned char *buf)
 {
+       if (sd_is_zoned(sdkp))
+               sdkp->capacity = 0;
        return 0;
 }

That should fix the above as well as the hang on boot with CONFIG_BLK_DEV_ZONED
disabled (for that one I do not totally understand what is going on...).

We do not have any host-aware disk for testing (as far as I know, nobody is
selling these anymore), so our test setup is a bit lame in this area. We'll rig
something up with tcmu-runner emulation to add tests for these devices to avoid
a repeat of such problem. And we'll make sure to add a test for
host-aware+partitions, since we at least know for sure there is one user :)

Johannes: The "goto out_free_index;" on sd_zbc_init_disk() failure is wrong I
think: the disk is already added and a ref taken on the dev, but out_free_index
does not seem to do cleanup for that. Need to revisit this.

Cheers.

-- 
Damien Le Moal
Western Digital Research