| Message ID | 20190815195823.GD2263813@devbig004.ftw2.facebook.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | [1/5] writeback: Generalize and expose wb_completion | expand |
On Thu 15-08-19 12:58:23, Tejun Heo wrote: > Separate out wb_get_lookup() which doesn't try to create one if there > isn't already one from wb_get_create(). This will be used by later > patches. > > Signed-off-by: Tejun Heo <tj@kernel.org> Looks good to me. You can add: Reviewed-by: Jan Kara <jack@suse.cz> Honza > --- > include/linux/backing-dev.h | 2 + > mm/backing-dev.c | 55 +++++++++++++++++++++++++++++--------------- > 2 files changed, 39 insertions(+), 18 deletions(-) > > --- a/include/linux/backing-dev.h > +++ b/include/linux/backing-dev.h > @@ -230,6 +230,8 @@ static inline int bdi_sched_wait(void *w > struct bdi_writeback_congested * > wb_congested_get_create(struct backing_dev_info *bdi, int blkcg_id, gfp_t gfp); > void wb_congested_put(struct bdi_writeback_congested *congested); > +struct bdi_writeback *wb_get_lookup(struct backing_dev_info *bdi, > + struct cgroup_subsys_state *memcg_css); > struct bdi_writeback *wb_get_create(struct backing_dev_info *bdi, > struct cgroup_subsys_state *memcg_css, > gfp_t gfp); > --- a/mm/backing-dev.c > +++ b/mm/backing-dev.c > @@ -618,13 +618,12 @@ out_put: > } > > /** > - * wb_get_create - get wb for a given memcg, create if necessary > + * wb_get_lookup - get wb for a given memcg > * @bdi: target bdi > * @memcg_css: cgroup_subsys_state of the target memcg (must have positive ref) > - * @gfp: allocation mask to use > * > - * Try to get the wb for @memcg_css on @bdi. If it doesn't exist, try to > - * create one. The returned wb has its refcount incremented. > + * Try to get the wb for @memcg_css on @bdi. The returned wb has its > + * refcount incremented. > * > * This function uses css_get() on @memcg_css and thus expects its refcnt > * to be positive on invocation. IOW, rcu_read_lock() protection on > @@ -641,6 +640,39 @@ out_put: > * each lookup. On mismatch, the existing wb is discarded and a new one is > * created. > */ > +struct bdi_writeback *wb_get_lookup(struct backing_dev_info *bdi, > + struct cgroup_subsys_state *memcg_css) > +{ > + struct bdi_writeback *wb; > + > + if (!memcg_css->parent) > + return &bdi->wb; > + > + rcu_read_lock(); > + wb = radix_tree_lookup(&bdi->cgwb_tree, memcg_css->id); > + if (wb) { > + struct cgroup_subsys_state *blkcg_css; > + > + /* see whether the blkcg association has changed */ > + blkcg_css = cgroup_get_e_css(memcg_css->cgroup, &io_cgrp_subsys); > + if (unlikely(wb->blkcg_css != blkcg_css || !wb_tryget(wb))) > + wb = NULL; > + css_put(blkcg_css); > + } > + rcu_read_unlock(); > + > + return wb; > +} > + > +/** > + * wb_get_create - get wb for a given memcg, create if necessary > + * @bdi: target bdi > + * @memcg_css: cgroup_subsys_state of the target memcg (must have positive ref) > + * @gfp: allocation mask to use > + * > + * Try to get the wb for @memcg_css on @bdi. If it doesn't exist, try to > + * create one. See wb_get_lookup() for more details. > + */ > struct bdi_writeback *wb_get_create(struct backing_dev_info *bdi, > struct cgroup_subsys_state *memcg_css, > gfp_t gfp) > @@ -653,20 +685,7 @@ struct bdi_writeback *wb_get_create(stru > return &bdi->wb; > > do { > - rcu_read_lock(); > - wb = radix_tree_lookup(&bdi->cgwb_tree, memcg_css->id); > - if (wb) { > - struct cgroup_subsys_state *blkcg_css; > - > - /* see whether the blkcg association has changed */ > - blkcg_css = cgroup_get_e_css(memcg_css->cgroup, > - &io_cgrp_subsys); > - if (unlikely(wb->blkcg_css != blkcg_css || > - !wb_tryget(wb))) > - wb = NULL; > - css_put(blkcg_css); > - } > - rcu_read_unlock(); > + wb = wb_get_lookup(bdi, memcg_css); > } while (!wb && !cgwb_create(bdi, memcg_css, gfp)); > > return wb;
--- a/include/linux/backing-dev.h +++ b/include/linux/backing-dev.h @@ -230,6 +230,8 @@ static inline int bdi_sched_wait(void *w struct bdi_writeback_congested * wb_congested_get_create(struct backing_dev_info *bdi, int blkcg_id, gfp_t gfp); void wb_congested_put(struct bdi_writeback_congested *congested); +struct bdi_writeback *wb_get_lookup(struct backing_dev_info *bdi, + struct cgroup_subsys_state *memcg_css); struct bdi_writeback *wb_get_create(struct backing_dev_info *bdi, struct cgroup_subsys_state *memcg_css, gfp_t gfp); --- a/mm/backing-dev.c +++ b/mm/backing-dev.c @@ -618,13 +618,12 @@ out_put: } /** - * wb_get_create - get wb for a given memcg, create if necessary + * wb_get_lookup - get wb for a given memcg * @bdi: target bdi * @memcg_css: cgroup_subsys_state of the target memcg (must have positive ref) - * @gfp: allocation mask to use * - * Try to get the wb for @memcg_css on @bdi. If it doesn't exist, try to - * create one. The returned wb has its refcount incremented. + * Try to get the wb for @memcg_css on @bdi. The returned wb has its + * refcount incremented. * * This function uses css_get() on @memcg_css and thus expects its refcnt * to be positive on invocation. IOW, rcu_read_lock() protection on @@ -641,6 +640,39 @@ out_put: * each lookup. On mismatch, the existing wb is discarded and a new one is * created. */ +struct bdi_writeback *wb_get_lookup(struct backing_dev_info *bdi, + struct cgroup_subsys_state *memcg_css) +{ + struct bdi_writeback *wb; + + if (!memcg_css->parent) + return &bdi->wb; + + rcu_read_lock(); + wb = radix_tree_lookup(&bdi->cgwb_tree, memcg_css->id); + if (wb) { + struct cgroup_subsys_state *blkcg_css; + + /* see whether the blkcg association has changed */ + blkcg_css = cgroup_get_e_css(memcg_css->cgroup, &io_cgrp_subsys); + if (unlikely(wb->blkcg_css != blkcg_css || !wb_tryget(wb))) + wb = NULL; + css_put(blkcg_css); + } + rcu_read_unlock(); + + return wb; +} + +/** + * wb_get_create - get wb for a given memcg, create if necessary + * @bdi: target bdi + * @memcg_css: cgroup_subsys_state of the target memcg (must have positive ref) + * @gfp: allocation mask to use + * + * Try to get the wb for @memcg_css on @bdi. If it doesn't exist, try to + * create one. See wb_get_lookup() for more details. + */ struct bdi_writeback *wb_get_create(struct backing_dev_info *bdi, struct cgroup_subsys_state *memcg_css, gfp_t gfp) @@ -653,20 +685,7 @@ struct bdi_writeback *wb_get_create(stru return &bdi->wb; do { - rcu_read_lock(); - wb = radix_tree_lookup(&bdi->cgwb_tree, memcg_css->id); - if (wb) { - struct cgroup_subsys_state *blkcg_css; - - /* see whether the blkcg association has changed */ - blkcg_css = cgroup_get_e_css(memcg_css->cgroup, - &io_cgrp_subsys); - if (unlikely(wb->blkcg_css != blkcg_css || - !wb_tryget(wb))) - wb = NULL; - css_put(blkcg_css); - } - rcu_read_unlock(); + wb = wb_get_lookup(bdi, memcg_css); } while (!wb && !cgwb_create(bdi, memcg_css, gfp)); return wb;
Separate out wb_get_lookup() which doesn't try to create one if there isn't already one from wb_get_create(). This will be used by later patches. Signed-off-by: Tejun Heo <tj@kernel.org> --- include/linux/backing-dev.h | 2 + mm/backing-dev.c | 55 +++++++++++++++++++++++++++++--------------- 2 files changed, 39 insertions(+), 18 deletions(-)