| Message ID | 1385456183-24840-8-git-send-email-pl@kamp.de |
|---|---|
| State | New |
| Headers | show |
Il 26/11/2013 09:56, Peter Lieven ha scritto: > this patch shortens requests to end at an aligned sector so that > the next request starts aligned. > > Signed-off-by: Peter Lieven <pl@kamp.de> > --- > qemu-img.c | 30 ++++++++++++++++++++---------- > 1 file changed, 20 insertions(+), 10 deletions(-) > > diff --git a/qemu-img.c b/qemu-img.c > index b076d44..1421f0f 100644 > --- a/qemu-img.c > +++ b/qemu-img.c > @@ -1124,8 +1124,7 @@ out3: > > static int img_convert(int argc, char **argv) > { > - int c, n, n1, bs_n, bs_i, compress, cluster_size, > - cluster_sectors, skip_create; > + int c, n, n1, bs_n, bs_i, compress, cluster_sectors, skip_create; > int64_t ret = 0; > int progress = 0, flags; > const char *fmt, *out_fmt, *cache, *out_baseimg, *out_filename; > @@ -1397,19 +1396,21 @@ static int img_convert(int argc, char **argv) > } > } > > + cluster_sectors = 0; > + ret = bdrv_get_info(out_bs, &bdi); > + if (ret < 0 && compress) { > + error_report("could not get block driver info"); > + goto out; > + } else { > + cluster_sectors = bdi.cluster_size / BDRV_SECTOR_SIZE; > + } > + > if (compress) { > - ret = bdrv_get_info(out_bs, &bdi); > - if (ret < 0) { > - error_report("could not get block driver info"); > - goto out; > - } > - cluster_size = bdi.cluster_size; > - if (cluster_size <= 0 || cluster_size > bufsectors * BDRV_SECTOR_SIZE) { > + if (cluster_sectors <= 0 || cluster_sectors > bufsectors) { > error_report("invalid cluster size"); > ret = -1; > goto out; > } > - cluster_sectors = cluster_size >> 9; > sector_num = 0; > > nb_sectors = total_sectors; > @@ -1547,6 +1548,15 @@ static int img_convert(int argc, char **argv) > n = nb_sectors; > } > > + /* round down request length to an aligned sector */ If you have to respin, /* do not bother doing this on short requests. They happen when we found an all-zero area, and the next sector to write will not be sector_num + n. */ > + if (cluster_sectors > 0 && n >= cluster_sectors) { > + int64_t next_aligned_sector = (sector_num + n); > + next_aligned_sector -= next_aligned_sector % cluster_sectors; > + if (sector_num + n > next_aligned_sector) { > + n = next_aligned_sector - sector_num; > + } > + } > + > if (n > bs_offset + bs_sectors - sector_num) { > n = bs_offset + bs_sectors - sector_num; > } > Reviewed-by: Paolo Bonzini <pbonzini@redhat.com>
diff --git a/qemu-img.c b/qemu-img.c index b076d44..1421f0f 100644 --- a/qemu-img.c +++ b/qemu-img.c @@ -1124,8 +1124,7 @@ out3: static int img_convert(int argc, char **argv) { - int c, n, n1, bs_n, bs_i, compress, cluster_size, - cluster_sectors, skip_create; + int c, n, n1, bs_n, bs_i, compress, cluster_sectors, skip_create; int64_t ret = 0; int progress = 0, flags; const char *fmt, *out_fmt, *cache, *out_baseimg, *out_filename; @@ -1397,19 +1396,21 @@ static int img_convert(int argc, char **argv) } } + cluster_sectors = 0; + ret = bdrv_get_info(out_bs, &bdi); + if (ret < 0 && compress) { + error_report("could not get block driver info"); + goto out; + } else { + cluster_sectors = bdi.cluster_size / BDRV_SECTOR_SIZE; + } + if (compress) { - ret = bdrv_get_info(out_bs, &bdi); - if (ret < 0) { - error_report("could not get block driver info"); - goto out; - } - cluster_size = bdi.cluster_size; - if (cluster_size <= 0 || cluster_size > bufsectors * BDRV_SECTOR_SIZE) { + if (cluster_sectors <= 0 || cluster_sectors > bufsectors) { error_report("invalid cluster size"); ret = -1; goto out; } - cluster_sectors = cluster_size >> 9; sector_num = 0; nb_sectors = total_sectors; @@ -1547,6 +1548,15 @@ static int img_convert(int argc, char **argv) n = nb_sectors; } + /* round down request length to an aligned sector */ + if (cluster_sectors > 0 && n >= cluster_sectors) { + int64_t next_aligned_sector = (sector_num + n); + next_aligned_sector -= next_aligned_sector % cluster_sectors; + if (sector_num + n > next_aligned_sector) { + n = next_aligned_sector - sector_num; + } + } + if (n > bs_offset + bs_sectors - sector_num) { n = bs_offset + bs_sectors - sector_num; }
this patch shortens requests to end at an aligned sector so that the next request starts aligned. Signed-off-by: Peter Lieven <pl@kamp.de> --- qemu-img.c | 30 ++++++++++++++++++++---------- 1 file changed, 20 insertions(+), 10 deletions(-)