| Message ID | 50200A46.3070508@inktank.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
On 08/06/2012 11:17 AM, Alex Elder wrote: > The only caller of rbd_header_from_disk() is rbd_read_header(). > It passes as allocated_snaps the number of snapshots it will > have received from the server for the snapshot context that > rbd_header_from_disk() is to interpret. The first time through > it provides 0--mainly to extract the number of snapshots from > the snapshot context header--so that it can allocate an > appropriately-sized buffer to receive the entire snapshot > context from the server in a second request. > > rbd_header_from_disk() will not fill in the array of snapshot ids > unless the number in the snapshot matches the number the caller > had allocated. > > This patch adjusts that logic a little further to be more efficient. > rbd_read_header() doesn't even examine the snapshot context unless > the snapshot count (stored in header->total_snaps) matches the > number of snapshots allocated. So rbd_header_from_disk() doesn't > need to allocate or fill in the snapshot context field at all in > that case. > > Signed-off-by: Alex Elder <elder@inktank.com> Reviewed-by: Josh Durgin <josh.durgin@inktank.com> > --- > drivers/block/rbd.c | 15 ++++++++++++--- > 1 file changed, 12 insertions(+), 3 deletions(-) > > Index: b/drivers/block/rbd.c > =================================================================== > --- a/drivers/block/rbd.c > +++ b/drivers/block/rbd.c > @@ -541,7 +541,14 @@ static int rbd_header_from_disk(struct r > header->comp_type = ondisk->options.comp_type; > header->total_snaps = snap_count; > > - /* Set up the snapshot context */ > + /* > + * If the number of snapshot ids provided by the caller > + * doesn't match the number in the entire context there's > + * no point in going further. Caller will try again after > + * getting an updated snapshot context from the server. > + */ > + if (allocated_snaps != snap_count) > + return 0; > > size = sizeof (struct ceph_snap_context); > size += snap_count * sizeof (header->snapc->snaps[0]); > @@ -553,8 +560,10 @@ static int rbd_header_from_disk(struct r > header->snapc->seq = le64_to_cpu(ondisk->snap_seq); > header->snapc->num_snaps = snap_count; > > - if (snap_count && allocated_snaps == snap_count) { > - int i; > + /* Fill in the snapshot information */ > + > + if (snap_count) { > + u32 i; > > for (i = 0; i < snap_count; i++) { > header->snapc->snaps[i] = > -- > To unsubscribe from this list: send the line "unsubscribe ceph-devel" in > the body of a message to majordomo@vger.kernel.org > More majordomo info at http://vger.kernel.org/majordomo-info.html -- To unsubscribe from this list: send the line "unsubscribe ceph-devel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
Index: b/drivers/block/rbd.c =================================================================== --- a/drivers/block/rbd.c +++ b/drivers/block/rbd.c @@ -541,7 +541,14 @@ static int rbd_header_from_disk(struct r header->comp_type = ondisk->options.comp_type; header->total_snaps = snap_count; - /* Set up the snapshot context */ + /* + * If the number of snapshot ids provided by the caller + * doesn't match the number in the entire context there's + * no point in going further. Caller will try again after + * getting an updated snapshot context from the server. + */ + if (allocated_snaps != snap_count) + return 0; size = sizeof (struct ceph_snap_context); size += snap_count * sizeof (header->snapc->snaps[0]); @@ -553,8 +560,10 @@ static int rbd_header_from_disk(struct r header->snapc->seq = le64_to_cpu(ondisk->snap_seq); header->snapc->num_snaps = snap_count; - if (snap_count && allocated_snaps == snap_count) { - int i; + /* Fill in the snapshot information */ + + if (snap_count) { + u32 i; for (i = 0; i < snap_count; i++) { header->snapc->snaps[i] =
The only caller of rbd_header_from_disk() is rbd_read_header(). It passes as allocated_snaps the number of snapshots it will have received from the server for the snapshot context that rbd_header_from_disk() is to interpret. The first time through it provides 0--mainly to extract the number of snapshots from the snapshot context header--so that it can allocate an appropriately-sized buffer to receive the entire snapshot context from the server in a second request. rbd_header_from_disk() will not fill in the array of snapshot ids unless the number in the snapshot matches the number the caller had allocated. This patch adjusts that logic a little further to be more efficient. rbd_read_header() doesn't even examine the snapshot context unless the snapshot count (stored in header->total_snaps) matches the number of snapshots allocated. So rbd_header_from_disk() doesn't need to allocate or fill in the snapshot context field at all in that case. Signed-off-by: Alex Elder <elder@inktank.com> --- drivers/block/rbd.c | 15 ++++++++++++--- 1 file changed, 12 insertions(+), 3 deletions(-) -- To unsubscribe from this list: send the line "unsubscribe ceph-devel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html