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&gt; Date: Fri Apr 3 14:13:02 2009 +0000 Fix sparse volume allocation reporting.