From: Shaohua Li <shli@xxxxxx> Hi, Currently blktrace isn't cgroup aware. blktrace prints out task name of current context, but the task of current context isn't always in the cgroup where the BIO comes from. We can't use task name to find out IO cgroup. For example, Writeback BIOs always comes from flusher thread but the BIOs are for different blk cgroups. Request could be requeued and dispatched from completely different tasks. MD/DM are another examples. This brings challenges if we want to use blktrace for performance tunning with cgroup enabled. This patchset try to fix the gap. We print out cgroup fhandle info in blktrace. Userspace can use open_by_handle_at() syscall to find the cgroup by fhandle. Or userspace can use name_to_handle_at() syscall to find fhandle for a cgroup and use a BPF program to filter out blktrace for a specific cgroup. The first 6 patches adds export operation handlers for kernfs, so userspace can use open_by_handle_at/name_to_handle_at to a kernfs file. Later patches make blktrace output cgroup info. Note, we export 64-bit inode number and 32-bit generation number for fhandle. Currently kernfs only supports 32-bit inode number actually because idr only supports 32-bit allocation. We had plan to support 64-bit inode number soon, as Tejun has concerns the 32-bit inode/generation could wrap easily. This patchset hasn't converted inode number to 64-bit yet. Thanks, Shaohua V1 -> V2: - Fix a bug in cgroup association - Fix build errors reported by 0day - Address some issues pointed out by Tejun Shaohua Li (12): kernfs: implement i_generation kernfs: use idr instead of ida to manage inode number kernfs: add an API to get kernfs node from inode number kernfs: don't set dentry->d_fsdata kernfs: introduce kernfs_node_id kernfs: add exportfs operations cgroup: export fhandle info for a cgroup blktrace: export cgroup info in trace block: always attach cgroup info into bio block: call __bio_free in bio_endio blktrace: add an option to allow displying cgroup path block: use standard blktrace API to output cgroup info for debug notes arch/x86/kernel/cpu/intel_rdt_rdtgroup.c | 2 +- block/bfq-iosched.h | 13 +- block/bio-integrity.c | 1 + block/bio.c | 2 + block/blk-throttle.c | 13 +- block/cfq-iosched.c | 15 +- fs/kernfs/dir.c | 101 +++++++++--- fs/kernfs/file.c | 10 +- fs/kernfs/inode.c | 9 +- fs/kernfs/kernfs-internal.h | 9 ++ fs/kernfs/mount.c | 144 +++++++++++++++-- fs/kernfs/symlink.c | 6 +- fs/sysfs/mount.c | 2 +- include/linux/blk-cgroup.h | 17 +- include/linux/blktrace_api.h | 13 +- include/linux/cgroup.h | 16 +- include/linux/exportfs.h | 11 ++ include/linux/kernfs.h | 36 ++++- include/uapi/linux/blktrace_api.h | 3 + kernel/cgroup/cgroup.c | 15 +- kernel/trace/blktrace.c | 259 ++++++++++++++++++++++--------- 21 files changed, 523 insertions(+), 174 deletions(-) -- 2.9.3
