On Thu 10-09-20 16:48:27, Christoph Hellwig wrote: > Just checking SB_I_CGROUPWB for cgroup writeback support is enough. > Either the file system allocates its own bdi (e.g. btrfs), in which case > it is known to support cgroup writeback, or the bdi comes from the block > layer, which always supports cgroup writeback. > > Signed-off-by: Christoph Hellwig <hch@xxxxxx> > Reviewed-by: Johannes Thumshirn <johannes.thumshirn@xxxxxxx> Makes sense. You can add: Reviewed-by: Jan Kara <jack@xxxxxxx> Honza > --- > block/blk-core.c | 1 - > fs/btrfs/disk-io.c | 1 - > include/linux/backing-dev.h | 8 +++----- > 3 files changed, 3 insertions(+), 7 deletions(-) > > diff --git a/block/blk-core.c b/block/blk-core.c > index 18c092f8d69175..d81ee511ec8b01 100644 > --- a/block/blk-core.c > +++ b/block/blk-core.c > @@ -538,7 +538,6 @@ struct request_queue *blk_alloc_queue(int node_id) > if (!q->stats) > goto fail_stats; > > - q->backing_dev_info->capabilities = BDI_CAP_CGROUP_WRITEBACK; > q->node = node_id; > > atomic_set(&q->nr_active_requests_shared_sbitmap, 0); > diff --git a/fs/btrfs/disk-io.c b/fs/btrfs/disk-io.c > index 047934cea25efa..e24927bddd5829 100644 > --- a/fs/btrfs/disk-io.c > +++ b/fs/btrfs/disk-io.c > @@ -3091,7 +3091,6 @@ int __cold open_ctree(struct super_block *sb, struct btrfs_fs_devices *fs_device > goto fail_sb_buffer; > } > > - sb->s_bdi->capabilities |= BDI_CAP_CGROUP_WRITEBACK; > sb->s_bdi->ra_pages *= btrfs_super_num_devices(disk_super); > sb->s_bdi->ra_pages = max(sb->s_bdi->ra_pages, SZ_4M / PAGE_SIZE); > > diff --git a/include/linux/backing-dev.h b/include/linux/backing-dev.h > index 0b06b2d26c9aa3..52583b6f2ea05d 100644 > --- a/include/linux/backing-dev.h > +++ b/include/linux/backing-dev.h > @@ -123,7 +123,6 @@ int bdi_set_max_ratio(struct backing_dev_info *bdi, unsigned int max_ratio); > * BDI_CAP_NO_ACCT_WB: Don't automatically account writeback pages > * BDI_CAP_STRICTLIMIT: Keep number of dirty pages below bdi threshold. > * > - * BDI_CAP_CGROUP_WRITEBACK: Supports cgroup-aware writeback. > * BDI_CAP_SYNCHRONOUS_IO: Device is so fast that asynchronous IO would be > * inefficient. > */ > @@ -233,9 +232,9 @@ int inode_congested(struct inode *inode, int cong_bits); > * inode_cgwb_enabled - test whether cgroup writeback is enabled on an inode > * @inode: inode of interest > * > - * cgroup writeback requires support from both the bdi and filesystem. > - * Also, both memcg and iocg have to be on the default hierarchy. Test > - * whether all conditions are met. > + * Cgroup writeback requires support from the filesystem. Also, both memcg and > + * iocg have to be on the default hierarchy. Test whether all conditions are > + * met. > * > * Note that the test result may change dynamically on the same inode > * depending on how memcg and iocg are configured. > @@ -247,7 +246,6 @@ static inline bool inode_cgwb_enabled(struct inode *inode) > return cgroup_subsys_on_dfl(memory_cgrp_subsys) && > cgroup_subsys_on_dfl(io_cgrp_subsys) && > bdi_cap_account_dirty(bdi) && > - (bdi->capabilities & BDI_CAP_CGROUP_WRITEBACK) && > (inode->i_sb->s_iflags & SB_I_CGROUPWB); > } > > -- > 2.28.0 > -- Jan Kara <jack@xxxxxxxx> SUSE Labs, CR
