linux.git/fs/ceph/subvolume_metrics.c, branch master Linux kernel source tree ceph: add subvolume metrics collection and reporting 2026-04-21T23:40:23+00:00 Alex Markuze amarkuze@redhat.com 2026-02-10T09:06:26+00:00 b1137e0b3d4bad1cad73fa9bac763c74ddd1813d Add complete infrastructure for per-subvolume I/O metrics collection and reporting to the MDS. This enables administrators to monitor I/O patterns at the subvolume granularity, which is useful for multi-tenant CephFS deployments. This patch adds: - CEPHFS_FEATURE_SUBVOLUME_METRICS feature flag for MDS negotiation - CEPH_SUBVOLUME_ID_NONE constant (0) for unknown/unset state - Red-black tree based metrics tracker for efficient per-subvolume aggregation with kmem_cache for entry allocations - Wire format encoding matching the MDS C++ AggregatedIOMetrics struct - Integration with the existing CLIENT_METRICS message - Recording of I/O operations from file read/write and writeback paths - Debugfs interfaces for monitoring (metrics/subvolumes, metrics/metric_features) Metrics tracked per subvolume include: - Read/write operation counts - Read/write byte counts - Read/write latency sums (for average calculation) The metrics are periodically sent to the MDS as part of the existing metrics reporting infrastructure when the MDS advertises support for the SUBVOLUME_METRICS feature. CEPH_SUBVOLUME_ID_NONE enforces subvolume_id immutability. Following the FUSE client convention, 0 means unknown/unset. Once an inode has a valid (non-zero) subvolume_id, it should not change during the inode's lifetime. Signed-off-by: Alex Markuze <amarkuze@redhat.com> Reviewed-by: Viacheslav Dubeyko <Slava.Dubeyko@ibm.com> Signed-off-by: Ilya Dryomov <idryomov@gmail.com> 
Add complete infrastructure for per-subvolume I/O metrics collection
and reporting to the MDS. This enables administrators to monitor I/O
patterns at the subvolume granularity, which is useful for multi-tenant
CephFS deployments.

This patch adds:
- CEPHFS_FEATURE_SUBVOLUME_METRICS feature flag for MDS negotiation
- CEPH_SUBVOLUME_ID_NONE constant (0) for unknown/unset state
- Red-black tree based metrics tracker for efficient per-subvolume
  aggregation with kmem_cache for entry allocations
- Wire format encoding matching the MDS C++ AggregatedIOMetrics struct
- Integration with the existing CLIENT_METRICS message
- Recording of I/O operations from file read/write and writeback paths
- Debugfs interfaces for monitoring (metrics/subvolumes, metrics/metric_features)

Metrics tracked per subvolume include:
- Read/write operation counts
- Read/write byte counts
- Read/write latency sums (for average calculation)

The metrics are periodically sent to the MDS as part of the existing
metrics reporting infrastructure when the MDS advertises support for
the SUBVOLUME_METRICS feature.

CEPH_SUBVOLUME_ID_NONE enforces subvolume_id immutability. Following
the FUSE client convention, 0 means unknown/unset. Once an inode has
a valid (non-zero) subvolume_id, it should not change during the
inode's lifetime.

Signed-off-by: Alex Markuze <amarkuze@redhat.com>
Reviewed-by: Viacheslav Dubeyko <Slava.Dubeyko@ibm.com>
Signed-off-by: Ilya Dryomov <idryomov@gmail.com>