Re: [libvirt] [PATCH 4/5] Implement virDomainGetBlockInfo in QEMU driver
On Tue, Apr 27, 2010 at 04:43:08PM -0600, Eric Blake wrote:
On 04/27/2010 01:35 PM, Daniel P. Berrange wrote:
> * src/qemu/qemu_driver.c: Implementation of virDomainGetBlockInfo
> * src/util/storage_file.h: Add DEV_BSIZE
> * src/storage/storage_backend.c: Remove DEV_BSIZE
> + if (S_ISREG(sb.st_mode)) {
> +#ifndef __MINGW32__
> + info->physical = (unsigned long long)sb.st_blocks *
> + (unsigned long long)DEV_BSIZE;
Is it worth checking sb.st_blksize rather than DEV_BSIZE on XSI systems
where that is part of struct stat? In particular, POSIX allows the
block size to be file-system dependent, and some file systems (like
NTFS) have 4k rather than 512 as the block size (is anyone daring enough
to use NTFS for raw file storage?).
This code is essentially identical to code in storage_backend.c & in
the future I will unify it. We did originally use sb.st_blksize in
the storage_backend.c impl, but this was not actually correct because
it gives the preferred size for efficient I/O, which is not the same
as the filesystem block size :-( Hence we have to hardcode 512.
The commit was this one, sadly no details in the commit message, but
they'll be in the mail archive somewhere:
commit e807e4d9e9a766bd00a89b0a9c179edfad52773c
Author: Cole Robinson <crobinso(a)redhat.com>
Date: Fri Apr 3 14:13:02 2009 +0000
Fix sparse volume allocation reporting.
Regards,
Daniel
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