blkio interface has become messy over time and is currently the largest. In addition to the inconsistent naming scheme, it has multiple stat files which report more or less the same thing, a number of debug stat files which expose internal details which shouldn't have been part of the public interface in the first place, recursive and non-recursive stats and leaf and non-leaf knobs. Both recursive vs. non-recursive and leaf vs. non-leaf distinctions don't make any sense on the unified hierarchy as only leaf cgroups can contain processes. cgroups is going through a major interface revision with the unified hierarchy involving significant fundamental usage changes and given that a significant portion of the interface doesn't make sense anymore, it's a good time to reorganize the interface. As the first step, this patch renames the external visible subsystem name from "blkio" to "io". This is more concise, matches the other two major subsystem names, "cpu" and "memory", and better suited as blkcg will be involved in anything writeback related too whether an actual block device is involved or not. As the subsystem legacy_name is set to "blkio", the only userland visible change outside the unified hierarchy is that blkcg is reported as "io" instead of "blkio" in the subsystem initialized message during boot. On the unified hierarchy, blkcg now appears as "io".
Showing the changes to include/linux/backing-dev.h (1 of 6 files). Show all
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| @@ -286,7 +286,7 @@ static inline struct bdi_writeback *wb_find_current(struct backing_dev_info *bdi · 285 unmodified lines | ||
| 286 | 286 | * %current's blkcg equals the effective blkcg of its memcg. No |
| 287 | 287 | * need to use the relatively expensive cgroup_get_e_css(). |
| 288 | 288 | */ |
| 289 | − if (likely(wb && wb->blkcg_css == task_css(current, blkio_cgrp_id))) | |
| 289 | + if (likely(wb && wb->blkcg_css == task_css(current, io_cgrp_id))) | |
| 290 | 290 | return wb; |
| 291 | 291 | return NULL; |
| 292 | 292 | } |