From: Matthew Rosato <mjrosato@linux.ibm.com>
To: Sam Li <faithilikerun@gmail.com>
Cc: "Stefan Hajnoczi" <stefanha@redhat.com>,
qemu-devel@nongnu.org, "Richard Henderson" <rth@twiddle.net>,
"Paolo Bonzini" <pbonzini@redhat.com>,
"Thomas Huth" <thuth@redhat.com>,
"Daniel P. Berrangé" <berrange@redhat.com>,
"Julia Suvorova" <jusual@redhat.com>,
"Aarushi Mehta" <mehta.aaru20@gmail.com>,
"Kevin Wolf" <kwolf@redhat.com>,
kvm@vger.kernel.org,
"Marc-André Lureau" <marcandre.lureau@redhat.com>,
"Markus Armbruster" <armbru@redhat.com>,
"Cornelia Huck" <cohuck@redhat.com>,
"Raphael Norwitz" <raphael.norwitz@nutanix.com>,
qemu-block@nongnu.org, "Michael S. Tsirkin" <mst@redhat.com>,
"Philippe Mathieu-Daudé" <philmd@linaro.org>,
"Hanna Reitz" <hreitz@redhat.com>,
"Eric Blake" <eblake@redhat.com>,
"Stefano Garzarella" <sgarzare@redhat.com>,
"Fam Zheng" <fam@euphon.net>, "Hannes Reinecke" <hare@suse.de>,
"Damien Le Moal" <damien.lemoal@opensource.wdc.com>,
"Dmitry Fomichev" <dmitry.fomichev@wdc.com>
Subject: Re: [PULL v2 02/16] block/file-posix: introduce helper functions for sysfs attributes
Date: Fri, 2 Jun 2023 14:41:35 -0400 [thread overview]
Message-ID: <638895f7-78b8-6e15-bbf8-916fc1513287@linux.ibm.com> (raw)
In-Reply-To: <CAAAx-8Km7J8dfz_63y1W5wE8MH7hJXo04ajY1A-ctv--x9CpGA@mail.gmail.com>
On 6/2/23 2:18 PM, Sam Li wrote:
> Matthew Rosato <mjrosato@linux.ibm.com> 于2023年6月1日周四 02:21写道：
>>
>> On 5/15/23 12:04 PM, Stefan Hajnoczi wrote:
>>> From: Sam Li <faithilikerun@gmail.com>
>>>
>>> Use get_sysfs_str_val() to get the string value of device
>>> zoned model. Then get_sysfs_zoned_model() can convert it to
>>> BlockZoneModel type of QEMU.
>>>
>>> Use get_sysfs_long_val() to get the long value of zoned device
>>> information.
>>
>> Hi Stefan, Sam,
>>
>> I am having an issue on s390x using virtio-blk-{pci,ccw} backed by an NVMe partition, and I've bisected the root cause to this commit.
>>
>> I noticed that tests which use the partition e.g. /dev/nvme0n1p1 as a backing device would fail, but those that use the namespace e.g. /dev/nvme0n1 would still succeed. The root issue appears to be that the block device associated with the partition does not have a "max_segments" attribute, and prior to this patch hdev_get_max_segment() would return -ENOENT in this case. After this patch, however, QEMU is instead crashing. It looks like g_file_get_contents is returning 0 with a len == 0 if the specified sysfs path does not exist. The following diff on top seems to resolve the issue for me:
>>
>>
>> diff --git a/block/file-posix.c b/block/file-posix.c
>> index 0ab158efba2..eeb0247c74e 100644
>> --- a/block/file-posix.c
>> +++ b/block/file-posix.c
>> @@ -1243,7 +1243,7 @@ static int get_sysfs_str_val(struct stat *st, const char *attribute,
>> major(st->st_rdev), minor(st->st_rdev),
>> attribute);
>> ret = g_file_get_contents(sysfspath, val, &len, NULL);
>> - if (ret == -1) {
>> + if (ret == -1 || len == 0) {
>> return -ENOENT;
>> }
>>
>
> Hi Matthew,
>
> Thanks for the information. After some checking, I think the bug here
> is that g_file_get_contens returns g_boolean value and the error case
> will return 0 instead of -1 in my previous code. Can the following
> line fix your issue on the s390x device?
>
> + if (ret == FALSE) {
>
> https://docs.gtk.org/glib/func.file_get_contents.html
Hi Sam,
Ah, good point, I didn't notice file_get_contents was meant to be a bool return and wondered why I was getting a return of 0 in the failing case, hence the check for len == 0.
Anyway, yes, I verified that checking for ret == FALSE fixes the issue. FWIW, along the same line I also checked that this works:
if (!g_file_get_contents(sysfspath, val, &len, NULL)) {
return -ENOENT;
}
which I personally think looks cleaner and matches the other uses of g_file_get_contents in QEMU. Could also get rid of ret and just return 0 at the bottom of the function.
Thanks,
Matt
next prev parent reply other threads:[~2023-06-02 18:42 UTC|newest]
Thread overview: 23+ messages / expand[flat|nested] mbox.gz Atom feed top
2023-05-15 16:04 [PULL v2 00/16] Block patches Stefan Hajnoczi
2023-05-15 16:04 ` [PULL v2 01/16] block/block-common: add zoned device structs Stefan Hajnoczi
2023-05-15 16:04 ` [PULL v2 02/16] block/file-posix: introduce helper functions for sysfs attributes Stefan Hajnoczi
[not found] ` <8b0ced3c-2fb5-2479-fe78-f4956ac037a6@linux.ibm.com>
2023-06-02 18:18 ` Sam Li
2023-06-02 18:41 ` Matthew Rosato [this message]
2023-06-02 18:45 ` Sam Li
2023-05-15 16:04 ` [PULL v2 03/16] block/block-backend: add block layer APIs resembling Linux ZonedBlockDevice ioctls Stefan Hajnoczi
2024-05-03 12:33 ` Peter Maydell
2024-05-07 15:09 ` Stefan Hajnoczi
2023-05-15 16:04 ` [PULL v2 04/16] block/raw-format: add zone operations to pass through requests Stefan Hajnoczi
2023-05-15 16:04 ` [PULL v2 05/16] block: add zoned BlockDriver check to block layer Stefan Hajnoczi
2023-05-15 16:04 ` [PULL v2 06/16] iotests: test new zone operations Stefan Hajnoczi
2023-05-15 16:04 ` [PULL v2 07/16] block: add some trace events for new block layer APIs Stefan Hajnoczi
2023-05-15 16:04 ` [PULL v2 08/16] docs/zoned-storage: add zoned device documentation Stefan Hajnoczi
2023-05-15 16:04 ` [PULL v2 09/16] file-posix: add tracking of the zone write pointers Stefan Hajnoczi
2023-05-15 16:05 ` [PULL v2 10/16] block: introduce zone append write for zoned devices Stefan Hajnoczi
2023-05-15 16:05 ` [PULL v2 11/16] qemu-iotests: test zone append operation Stefan Hajnoczi
2023-05-15 16:05 ` [PULL v2 12/16] block: add some trace events for zone append Stefan Hajnoczi
2023-05-15 16:05 ` [PULL v2 13/16] virtio-blk: add zoned storage emulation for zoned devices Stefan Hajnoczi
2023-05-15 16:05 ` [PULL v2 14/16] block: add accounting for zone append operation Stefan Hajnoczi
2023-05-15 16:05 ` [PULL v2 15/16] virtio-blk: add some trace events for zoned emulation Stefan Hajnoczi
2023-05-15 16:05 ` [PULL v2 16/16] docs/zoned-storage:add zoned emulation use case Stefan Hajnoczi
2023-05-15 23:37 ` [PULL v2 00/16] Block patches Richard Henderson
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