From: Eduardo Habkost <ehabkost@redhat.com>
To: Xiao Guangrong <guangrong.xiao@linux.intel.com>
Cc: Kevin Wolf <kwolf@redhat.com>,
vsementsov@virtuozzo.com, qemu-block@nongnu.org,
kvm@vger.kernel.org, mst@redhat.com, gleb@kernel.org,
mtosatti@redhat.com, qemu-devel@nongnu.org, stefanha@redhat.com,
imammedo@redhat.com, pbonzini@redhat.com,
dan.j.williams@intel.com, rth@twiddle.net
Subject: Re: [PATCH v7 12/35] util: let qemu_fd_getlength support block device
Date: Mon, 9 Nov 2015 16:43:22 -0200 [thread overview]
Message-ID: <20151109184322.GD4180@thinpad.lan.raisama.net> (raw)
In-Reply-To: <56403603.20002@linux.intel.com>
On Mon, Nov 09, 2015 at 01:58:27PM +0800, Xiao Guangrong wrote:
>
>
> On 11/06/2015 11:54 PM, Eduardo Habkost wrote:
> >On Mon, Nov 02, 2015 at 05:13:14PM +0800, Xiao Guangrong wrote:
> >>lseek can not work for all block devices as the man page says:
> >>| Some devices are incapable of seeking and POSIX does not specify
> >>| which devices must support lseek().
> >>
> >>This patch tries to add the support on Linux by using BLKGETSIZE64
> >>ioctl
> >>
> >>Signed-off-by: Xiao Guangrong <guangrong.xiao@linux.intel.com>
> >
> >On which cases is this patch necessary? Do you know any examples of
> >Linux block devices that won't work with lseek(SEEK_END)?
>
> To be honest, i have not checked all block device, this patch was made
> based on the man page. However, i do not mind drop this patch (and maybe
> other patches) to make this pachset smaller. BLKGETSIZE64 can be added
> in the future if we meet such device.
By looking at the Linux source code implementing BLKGETSIZE64, it looks
like it should work for all block devices where SEEK_END works:
* BLKGETSIZE64 returns i_size_read(bdev->bd_inode)
(block/ioctl.c:blkdev_ioctl())
* llseek(SEEK_END) uses i_size_read(bd_inode) as the offset
(fs/block_dev.c:block_llseek())
That's probably why raw_getlength() never needed a Linux-specific
BLKGETSIZE call.
--
Eduardo
WARNING: multiple messages have this Message-ID (diff)
From: Eduardo Habkost <ehabkost@redhat.com>
To: Xiao Guangrong <guangrong.xiao@linux.intel.com>
Cc: Kevin Wolf <kwolf@redhat.com>,
vsementsov@virtuozzo.com, qemu-block@nongnu.org,
kvm@vger.kernel.org, mst@redhat.com, gleb@kernel.org,
mtosatti@redhat.com, qemu-devel@nongnu.org, stefanha@redhat.com,
imammedo@redhat.com, pbonzini@redhat.com,
dan.j.williams@intel.com, rth@twiddle.net
Subject: Re: [Qemu-devel] [PATCH v7 12/35] util: let qemu_fd_getlength support block device
Date: Mon, 9 Nov 2015 16:43:22 -0200 [thread overview]
Message-ID: <20151109184322.GD4180@thinpad.lan.raisama.net> (raw)
In-Reply-To: <56403603.20002@linux.intel.com>
On Mon, Nov 09, 2015 at 01:58:27PM +0800, Xiao Guangrong wrote:
>
>
> On 11/06/2015 11:54 PM, Eduardo Habkost wrote:
> >On Mon, Nov 02, 2015 at 05:13:14PM +0800, Xiao Guangrong wrote:
> >>lseek can not work for all block devices as the man page says:
> >>| Some devices are incapable of seeking and POSIX does not specify
> >>| which devices must support lseek().
> >>
> >>This patch tries to add the support on Linux by using BLKGETSIZE64
> >>ioctl
> >>
> >>Signed-off-by: Xiao Guangrong <guangrong.xiao@linux.intel.com>
> >
> >On which cases is this patch necessary? Do you know any examples of
> >Linux block devices that won't work with lseek(SEEK_END)?
>
> To be honest, i have not checked all block device, this patch was made
> based on the man page. However, i do not mind drop this patch (and maybe
> other patches) to make this pachset smaller. BLKGETSIZE64 can be added
> in the future if we meet such device.
By looking at the Linux source code implementing BLKGETSIZE64, it looks
like it should work for all block devices where SEEK_END works:
* BLKGETSIZE64 returns i_size_read(bdev->bd_inode)
(block/ioctl.c:blkdev_ioctl())
* llseek(SEEK_END) uses i_size_read(bd_inode) as the offset
(fs/block_dev.c:block_llseek())
That's probably why raw_getlength() never needed a Linux-specific
BLKGETSIZE call.
--
Eduardo
next prev parent reply other threads:[~2015-11-09 18:43 UTC|newest]
Thread overview: 200+ messages / expand[flat|nested] mbox.gz Atom feed top
2015-11-02 9:13 [PATCH v7 00/35] implement vNVDIMM Xiao Guangrong
2015-11-02 9:13 ` [Qemu-devel] " Xiao Guangrong
2015-11-02 9:13 ` [PATCH v7 01/35] acpi: add aml_derefof Xiao Guangrong
2015-11-02 9:13 ` [Qemu-devel] " Xiao Guangrong
2015-11-02 9:13 ` [PATCH v7 02/35] acpi: add aml_sizeof Xiao Guangrong
2015-11-02 9:13 ` [Qemu-devel] " Xiao Guangrong
2015-11-02 9:13 ` [PATCH v7 03/35] acpi: add aml_create_field Xiao Guangrong
2015-11-02 9:13 ` [Qemu-devel] " Xiao Guangrong
2015-11-03 6:14 ` Shannon Zhao
2015-11-03 6:14 ` [Qemu-devel] " Shannon Zhao
2015-11-03 14:52 ` Xiao Guangrong
2015-11-02 9:13 ` [PATCH v7 04/35] acpi: add aml_concatenate Xiao Guangrong
2015-11-02 9:13 ` [Qemu-devel] " Xiao Guangrong
2015-11-02 9:13 ` [PATCH v7 05/35] acpi: add aml_object_type Xiao Guangrong
2015-11-02 9:13 ` [Qemu-devel] " Xiao Guangrong
2015-11-02 9:13 ` [PATCH v7 06/35] acpi: add aml_method_serialized Xiao Guangrong
2015-11-02 9:13 ` [Qemu-devel] " Xiao Guangrong
2015-11-03 12:30 ` Igor Mammedov
2015-11-03 12:30 ` Igor Mammedov
2015-11-03 13:27 ` Xiao Guangrong
2015-11-03 13:27 ` Xiao Guangrong
2015-11-02 9:13 ` [PATCH v7 07/35] util: introduce qemu_file_get_page_size() Xiao Guangrong
2015-11-02 9:13 ` [Qemu-devel] " Xiao Guangrong
2015-11-02 13:56 ` Vladimir Sementsov-Ogievskiy
2015-11-02 13:56 ` [Qemu-devel] " Vladimir Sementsov-Ogievskiy
2015-11-06 15:36 ` Eduardo Habkost
2015-11-06 15:36 ` [Qemu-devel] " Eduardo Habkost
2015-11-09 4:36 ` Xiao Guangrong
2015-11-09 4:36 ` [Qemu-devel] " Xiao Guangrong
2015-11-09 18:34 ` Eduardo Habkost
2015-11-09 18:34 ` [Qemu-devel] " Eduardo Habkost
2015-11-02 9:13 ` [PATCH v7 08/35] exec: allow memory to be allocated from any kind of path Xiao Guangrong
2015-11-02 9:13 ` [Qemu-devel] " Xiao Guangrong
2015-11-02 14:51 ` Vladimir Sementsov-Ogievskiy
2015-11-02 14:51 ` [Qemu-devel] " Vladimir Sementsov-Ogievskiy
2015-11-02 15:22 ` Xiao Guangrong
2015-11-02 15:22 ` [Qemu-devel] " Xiao Guangrong
2015-11-02 15:52 ` Vladimir Sementsov-Ogievskiy
2015-11-02 15:52 ` [Qemu-devel] " Vladimir Sementsov-Ogievskiy
2015-11-03 23:00 ` Eduardo Habkost
2015-11-03 23:00 ` [Qemu-devel] " Eduardo Habkost
2015-11-04 3:12 ` Xiao Guangrong
2015-11-04 3:12 ` [Qemu-devel] " Xiao Guangrong
2015-11-04 12:40 ` Eduardo Habkost
2015-11-04 12:40 ` [Qemu-devel] " Eduardo Habkost
2015-11-04 14:22 ` Xiao Guangrong
2015-11-04 14:22 ` [Qemu-devel] " Xiao Guangrong
2015-11-02 9:13 ` [PATCH v7 09/35] exec: allow file_ram_alloc to work on file Xiao Guangrong
2015-11-02 9:13 ` [Qemu-devel] " Xiao Guangrong
2015-11-02 15:12 ` Vladimir Sementsov-Ogievskiy
2015-11-02 15:12 ` [Qemu-devel] " Vladimir Sementsov-Ogievskiy
2015-11-02 15:25 ` Xiao Guangrong
2015-11-02 15:25 ` [Qemu-devel] " Xiao Guangrong
2015-11-02 15:58 ` Vladimir Sementsov-Ogievskiy
2015-11-02 15:58 ` Vladimir Sementsov-Ogievskiy
2015-11-02 21:12 ` Paolo Bonzini
2015-11-02 21:12 ` [Qemu-devel] " Paolo Bonzini
2015-11-03 3:56 ` Xiao Guangrong
2015-11-03 3:56 ` [Qemu-devel] " Xiao Guangrong
2015-11-03 13:55 ` Paolo Bonzini
2015-11-03 13:55 ` [Qemu-devel] " Paolo Bonzini
2015-11-03 14:26 ` Xiao Guangrong
2015-11-03 14:26 ` [Qemu-devel] " Xiao Guangrong
2015-11-03 12:34 ` Igor Mammedov
2015-11-03 12:34 ` [Qemu-devel] " Igor Mammedov
2015-11-03 13:32 ` Xiao Guangrong
2015-11-03 13:32 ` [Qemu-devel] " Xiao Guangrong
2015-11-02 9:13 ` [PATCH v7 10/35] hostmem-file: clean up memory allocation Xiao Guangrong
2015-11-02 9:13 ` [Qemu-devel] " Xiao Guangrong
2015-11-02 9:13 ` [PATCH v7 11/35] util: introduce qemu_file_getlength() Xiao Guangrong
2015-11-02 9:13 ` [Qemu-devel] " Xiao Guangrong
2015-11-02 15:26 ` Vladimir Sementsov-Ogievskiy
2015-11-02 15:26 ` [Qemu-devel] " Vladimir Sementsov-Ogievskiy
2015-11-03 23:21 ` Eduardo Habkost
2015-11-03 23:21 ` [Qemu-devel] " Eduardo Habkost
2015-11-04 3:17 ` Xiao Guangrong
2015-11-04 3:17 ` [Qemu-devel] " Xiao Guangrong
2015-11-04 14:44 ` Eduardo Habkost
2015-11-04 14:44 ` [Qemu-devel] " Eduardo Habkost
2015-11-04 14:44 ` Xiao Guangrong
2015-11-04 14:44 ` [Qemu-devel] " Xiao Guangrong
2015-11-06 15:50 ` Eduardo Habkost
2015-11-06 15:50 ` [Qemu-devel] " Eduardo Habkost
2015-11-09 4:44 ` Xiao Guangrong
2015-11-09 4:44 ` [Qemu-devel] " Xiao Guangrong
2015-11-09 19:21 ` Eduardo Habkost
2015-11-09 19:21 ` [Qemu-devel] " Eduardo Habkost
2015-11-02 9:13 ` [PATCH v7 12/35] util: let qemu_fd_getlength support block device Xiao Guangrong
2015-11-02 9:13 ` [Qemu-devel] " Xiao Guangrong
2015-11-02 16:11 ` Vladimir Sementsov-Ogievskiy
2015-11-02 16:11 ` [Qemu-devel] " Vladimir Sementsov-Ogievskiy
2015-11-02 16:21 ` Xiao Guangrong
2015-11-02 16:21 ` [Qemu-devel] " Xiao Guangrong
2015-11-06 15:44 ` Eduardo Habkost
2015-11-06 15:44 ` [Qemu-devel] " Eduardo Habkost
2015-11-06 15:48 ` Eduardo Habkost
2015-11-06 15:48 ` [Qemu-devel] " Eduardo Habkost
2015-11-06 15:54 ` Eduardo Habkost
2015-11-06 15:54 ` [Qemu-devel] " Eduardo Habkost
2015-11-09 5:58 ` Xiao Guangrong
2015-11-09 5:58 ` [Qemu-devel] " Xiao Guangrong
2015-11-09 18:43 ` Eduardo Habkost [this message]
2015-11-09 18:43 ` Eduardo Habkost
2015-11-02 9:13 ` [PATCH v7 13/35] hostmem-file: use whole file size if possible Xiao Guangrong
2015-11-02 9:13 ` [Qemu-devel] " Xiao Guangrong
2015-11-02 17:09 ` Vladimir Sementsov-Ogievskiy
2015-11-02 17:09 ` [Qemu-devel] " Vladimir Sementsov-Ogievskiy
2015-11-03 14:51 ` Xiao Guangrong
2015-11-03 14:51 ` [Qemu-devel] " Xiao Guangrong
2015-11-02 9:13 ` [PATCH v7 14/35] pc-dimm: remove DEFAULT_PC_DIMMSIZE Xiao Guangrong
2015-11-02 9:13 ` [Qemu-devel] " Xiao Guangrong
2015-11-02 9:13 ` [PATCH v7 15/35] pc-dimm: make pc_existing_dimms_capacity static and rename it Xiao Guangrong
2015-11-02 9:13 ` [Qemu-devel] " Xiao Guangrong
2015-11-02 9:13 ` [PATCH v7 16/35] pc-dimm: drop the prefix of pc-dimm Xiao Guangrong
2015-11-02 9:13 ` [Qemu-devel] " Xiao Guangrong
2015-11-02 9:13 ` [PATCH v7 17/35] stubs: rename qmp_pc_dimm_device_list.c Xiao Guangrong
2015-11-02 9:13 ` [Qemu-devel] " Xiao Guangrong
2015-11-02 9:13 ` [PATCH v7 18/35] pc-dimm: rename pc-dimm.c and pc-dimm.h Xiao Guangrong
2015-11-02 9:13 ` [Qemu-devel] " Xiao Guangrong
2015-11-02 9:13 ` [PATCH v7 19/35] dimm: abstract dimm device from pc-dimm Xiao Guangrong
2015-11-02 9:13 ` [Qemu-devel] " Xiao Guangrong
2015-11-02 9:13 ` [PATCH v7 20/35] dimm: get mapped memory region from DIMMDeviceClass->get_memory_region Xiao Guangrong
2015-11-02 9:13 ` [Qemu-devel] " Xiao Guangrong
2015-11-02 12:19 ` Vladimir Sementsov-Ogievskiy
2015-11-02 12:19 ` [Qemu-devel] " Vladimir Sementsov-Ogievskiy
2015-11-02 13:08 ` Xiao Guangrong
2015-11-02 13:08 ` [Qemu-devel] " Xiao Guangrong
2015-11-02 14:26 ` Vladimir Sementsov-Ogievskiy
2015-11-02 14:26 ` [Qemu-devel] " Vladimir Sementsov-Ogievskiy
2015-11-02 15:06 ` Xiao Guangrong
2015-11-02 15:06 ` [Qemu-devel] " Xiao Guangrong
2015-11-02 16:16 ` Vladimir Sementsov-Ogievskiy
2015-11-02 16:16 ` [Qemu-devel] " Vladimir Sementsov-Ogievskiy
2015-11-03 14:47 ` Xiao Guangrong
2015-11-03 14:47 ` [Qemu-devel] " Xiao Guangrong
2015-11-05 8:53 ` Vladimir Sementsov-Ogievskiy
2015-11-05 8:53 ` [Qemu-devel] " Vladimir Sementsov-Ogievskiy
2015-11-05 17:29 ` Eduardo Habkost
2015-11-05 17:29 ` [Qemu-devel] " Eduardo Habkost
2015-11-06 2:50 ` Xiao Guangrong
2015-11-06 2:50 ` [Qemu-devel] " Xiao Guangrong
2015-11-02 9:13 ` [PATCH v7 21/35] dimm: keep the state of the whole backend memory Xiao Guangrong
2015-11-02 9:13 ` [Qemu-devel] " Xiao Guangrong
2015-11-02 9:13 ` [PATCH v7 22/35] dimm: introduce realize callback Xiao Guangrong
2015-11-02 9:13 ` [Qemu-devel] " Xiao Guangrong
2015-11-02 9:13 ` [PATCH v7 23/35] nvdimm: implement NVDIMM device abstract Xiao Guangrong
2015-11-02 9:13 ` [Qemu-devel] " Xiao Guangrong
2015-11-13 16:53 ` Vladimir Sementsov-Ogievskiy
2015-11-13 16:53 ` [Qemu-devel] " Vladimir Sementsov-Ogievskiy
2015-11-02 9:13 ` [PATCH v7 24/35] docs: add NVDIMM ACPI documentation Xiao Guangrong
2015-11-02 9:13 ` [Qemu-devel] " Xiao Guangrong
2015-11-02 9:13 ` [PATCH v7 25/35] nvdimm acpi: init the resource used by NVDIMM ACPI Xiao Guangrong
2015-11-02 9:13 ` [Qemu-devel] " Xiao Guangrong
2015-11-05 9:58 ` Igor Mammedov
2015-11-05 9:58 ` [Qemu-devel] " Igor Mammedov
2015-11-05 10:15 ` Xiao Guangrong
2015-11-05 10:15 ` [Qemu-devel] " Xiao Guangrong
2015-11-05 13:03 ` Igor Mammedov
2015-11-05 13:03 ` [Qemu-devel] " Igor Mammedov
2015-11-05 13:33 ` Xiao Guangrong
2015-11-05 13:33 ` [Qemu-devel] " Xiao Guangrong
2015-11-05 14:49 ` Igor Mammedov
2015-11-05 14:49 ` [Qemu-devel] " Igor Mammedov
2015-11-06 8:31 ` Xiao Guangrong
2015-11-06 8:31 ` [Qemu-devel] " Xiao Guangrong
2015-11-06 8:56 ` Xiao Guangrong
2015-11-06 8:56 ` [Qemu-devel] " Xiao Guangrong
2015-11-09 11:13 ` Igor Mammedov
2015-11-11 3:01 ` Ask for ACK (was Re: [PATCH v7 25/35] nvdimm acpi: init the resource used by NVDIMM ACPI) Xiao Guangrong
2015-11-11 3:01 ` [Qemu-devel] " Xiao Guangrong
2015-11-02 9:13 ` [PATCH v7 26/35] nvdimm acpi: build ACPI NFIT table Xiao Guangrong
2015-11-02 9:13 ` [Qemu-devel] " Xiao Guangrong
2015-11-02 9:13 ` [PATCH v7 27/35] nvdimm acpi: build ACPI nvdimm devices Xiao Guangrong
2015-11-02 9:13 ` [Qemu-devel] " Xiao Guangrong
2015-11-03 13:13 ` Igor Mammedov
2015-11-03 13:13 ` [Qemu-devel] " Igor Mammedov
2015-11-03 14:22 ` Xiao Guangrong
2015-11-03 14:22 ` [Qemu-devel] " Xiao Guangrong
2015-11-04 8:56 ` Igor Mammedov
2015-11-04 8:56 ` [Qemu-devel] " Igor Mammedov
2015-11-04 14:11 ` Xiao Guangrong
2015-11-04 14:11 ` [Qemu-devel] " Xiao Guangrong
2015-11-02 9:13 ` [PATCH v7 28/35] nvdimm acpi: save arg3 for NVDIMM device _DSM method Xiao Guangrong
2015-11-02 9:13 ` [Qemu-devel] " Xiao Guangrong
2015-11-02 9:13 ` [PATCH v7 29/35] nvdimm acpi: support function 0 Xiao Guangrong
2015-11-02 9:13 ` [Qemu-devel] " Xiao Guangrong
2015-11-02 9:13 ` [PATCH v7 30/35] nvdimm acpi: support Get Namespace Label Size function Xiao Guangrong
2015-11-02 9:13 ` [Qemu-devel] " Xiao Guangrong
2015-11-02 9:13 ` [PATCH v7 31/35] nvdimm acpi: support Get Namespace Label Data function Xiao Guangrong
2015-11-02 9:13 ` [Qemu-devel] " Xiao Guangrong
2015-11-02 9:13 ` [PATCH v7 32/35] nvdimm acpi: support Set " Xiao Guangrong
2015-11-02 9:13 ` [Qemu-devel] " Xiao Guangrong
2015-11-02 9:13 ` [PATCH v7 33/35] nvdimm: allow using whole backend memory as pmem Xiao Guangrong
2015-11-02 9:13 ` [Qemu-devel] " Xiao Guangrong
2015-11-02 9:13 ` [PATCH v7 34/35] nvdimm acpi: support _FIT method Xiao Guangrong
2015-11-02 9:13 ` [Qemu-devel] " Xiao Guangrong
2015-11-02 9:13 ` [PATCH v7 35/35] nvdimm: add maintain info Xiao Guangrong
2015-11-02 9:13 ` [Qemu-devel] " Xiao Guangrong
2015-11-02 11:51 ` [PATCH v7 00/35] implement vNVDIMM Stefan Hajnoczi
2015-11-02 11:51 ` [Qemu-devel] " Stefan Hajnoczi
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