On Thu, Mar 20, 2014 at 02:22:19PM +0100, Kevin Wolf wrote: > Am 17.03.2014 um 07:53 hat Hu Tao geschrieben: > > This patch adds a new option preallocation for raw format, and implements > > full preallocation. > > > > Signed-off-by: Hu Tao <hu...@cn.fujitsu.com> > > --- > > block/raw-posix.c | 43 +++++++++++++++++++++++++++++++++++-------- > > 1 file changed, 35 insertions(+), 8 deletions(-) > > > > diff --git a/block/raw-posix.c b/block/raw-posix.c > > index a363b71..e004ff8 100644 > > --- a/block/raw-posix.c > > +++ b/block/raw-posix.c > > @@ -1240,6 +1240,7 @@ static int raw_create(const char *filename, > > QEMUOptionParameter *options, > > int fd; > > int result = 0; > > int64_t total_size = 0; > > + PreallocMode prealloc = PREALLOC_MODE_OFF; > > > > strstart(filename, "file:", &filename); > > > > @@ -1247,6 +1248,16 @@ static int raw_create(const char *filename, > > QEMUOptionParameter *options, > > while (options && options->name) { > > if (!strcmp(options->name, BLOCK_OPT_SIZE)) { > > total_size = options->value.n & BDRV_SECTOR_MASK; > > + } else if (!strcmp(options->name, BLOCK_OPT_PREALLOC)) { > > + if (!options->value.s || !strcmp(options->value.s, "off")) { > > + prealloc = PREALLOC_MODE_OFF; > > + } else if (!strcmp(options->value.s, "full")) { > > + prealloc = PREALLOC_MODE_FULL; > > + } else { > > + error_setg(errp, "Invalid preallocation mode: '%s'", > > + options->value.s); > > + return -EINVAL; > > + } > > } > > options++; > > } > > @@ -1256,16 +1267,27 @@ static int raw_create(const char *filename, > > QEMUOptionParameter *options, > > if (fd < 0) { > > result = -errno; > > error_setg_errno(errp, -result, "Could not create file"); > > - } else { > > - if (ftruncate(fd, total_size) != 0) { > > - result = -errno; > > - error_setg_errno(errp, -result, "Could not resize file"); > > - } > > - if (qemu_close(fd) != 0) { > > - result = -errno; > > - error_setg_errno(errp, -result, "Could not close the new > > file"); > > + goto out; > > + } > > + if (ftruncate(fd, total_size) != 0) { > > + result = -errno; > > + error_setg_errno(errp, -result, "Could not resize file"); > > + goto out_close; > > + } > > + if (prealloc == PREALLOC_MODE_FULL) { > > + /* posix_fallocate() doesn't set errno. */ > > + result = -posix_fallocate(fd, 0, total_size); > > + if (result != 0) { > > + error_setg_errno(errp, -result, > > + "Could not preallocate data for the new > > file"); > > } > > Can you please make that PREALLOC_MODE_METADATA? > > You're really only preallocating metadata on a filesystem level here. If > the backing block device were thin provisioned, we wouldn't make any
Thanks for reminding me! I was not aware of thin privisioning case. > attempt to preallocate that (e.g. with a loop writing zeroes or > bdrv_write_zeroes() without BDRV_REQ_MAY_UNMAP), so I'd hardly call it > "full" preallocation. Just to confirm it, we can only do full preallocation by writing zeros to the backing device? If yes, I agree that this patch doesn't do full preallocation. In the other hand, this patch changes the behaviour of qcow2 metadata preallocation, I think it is not reasonable to still call it PREALLOC_MODE_METADATA. What's your opinion? Regards, Hu Tao