| Message ID | 20190307180834.22008-4-andrea.righi@canonical.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | blkcg: sync() isolation | expand |
On Thu, Mar 07, 2019 at 07:08:34PM +0100, Andrea Righi wrote: > Keep track of the inodes that have been dirtied by each blkcg cgroup and > make sure that a blkcg issuing a sync() can trigger the writeback + wait > of only those pages that belong to the cgroup itself. > > This behavior is applied only when io.sync_isolation is enabled in the > cgroup, otherwise the old behavior is applied: sync() triggers the > writeback of any dirty page. > > Signed-off-by: Andrea Righi <andrea.righi@canonical.com> > --- > block/blk-cgroup.c | 47 ++++++++++++++++++++++++++++++++++ > fs/fs-writeback.c | 52 +++++++++++++++++++++++++++++++++++--- > fs/inode.c | 1 + > include/linux/blk-cgroup.h | 22 ++++++++++++++++ > include/linux/fs.h | 4 +++ > mm/page-writeback.c | 1 + > 6 files changed, 124 insertions(+), 3 deletions(-) > > diff --git a/block/blk-cgroup.c b/block/blk-cgroup.c > index 4305e78d1bb2..7d3b26ba4575 100644 > --- a/block/blk-cgroup.c > +++ b/block/blk-cgroup.c > @@ -1480,6 +1480,53 @@ void blkcg_stop_wb_wait_on_bdi(struct backing_dev_info *bdi) > spin_unlock(&blkcg_wb_sleeper_lock); > rcu_read_unlock(); > } > + > +/** > + * blkcg_set_mapping_dirty - set owner of a dirty mapping > + * @mapping: target address space > + * > + * Set the current blkcg as the owner of the address space @mapping (the first > + * blkcg that dirties @mapping becomes the owner). > + */ > +void blkcg_set_mapping_dirty(struct address_space *mapping) > +{ > + struct blkcg *curr_blkcg, *blkcg; > + > + if (mapping_tagged(mapping, PAGECACHE_TAG_WRITEBACK) || > + mapping_tagged(mapping, PAGECACHE_TAG_DIRTY)) > + return; > + > + rcu_read_lock(); > + curr_blkcg = blkcg_from_current(); > + blkcg = blkcg_from_mapping(mapping); > + if (curr_blkcg != blkcg) { > + if (blkcg) > + css_put(&blkcg->css); > + css_get(&curr_blkcg->css); > + rcu_assign_pointer(mapping->i_blkcg, curr_blkcg); > + } > + rcu_read_unlock(); > +} > + > +/** > + * blkcg_set_mapping_clean - clear the owner of a dirty mapping > + * @mapping: target address space > + * > + * Unset the owner of @mapping when it becomes clean. > + */ > + > +void blkcg_set_mapping_clean(struct address_space *mapping) > +{ > + struct blkcg *blkcg; > + > + rcu_read_lock(); > + blkcg = rcu_dereference(mapping->i_blkcg); > + if (blkcg) { > + css_put(&blkcg->css); > + RCU_INIT_POINTER(mapping->i_blkcg, NULL); > + } > + rcu_read_unlock(); > +} > #endif > Why do we need this? We already have the inode_attach_wb(), which has the blkcg_css embedded in it for whoever dirtied the inode first. Can we not just use that? Thanks, Josef
On Thu, Mar 07, 2019 at 05:07:01PM -0500, Josef Bacik wrote: > On Thu, Mar 07, 2019 at 07:08:34PM +0100, Andrea Righi wrote: > > Keep track of the inodes that have been dirtied by each blkcg cgroup and > > make sure that a blkcg issuing a sync() can trigger the writeback + wait > > of only those pages that belong to the cgroup itself. > > > > This behavior is applied only when io.sync_isolation is enabled in the > > cgroup, otherwise the old behavior is applied: sync() triggers the > > writeback of any dirty page. > > > > Signed-off-by: Andrea Righi <andrea.righi@canonical.com> > > --- > > block/blk-cgroup.c | 47 ++++++++++++++++++++++++++++++++++ > > fs/fs-writeback.c | 52 +++++++++++++++++++++++++++++++++++--- > > fs/inode.c | 1 + > > include/linux/blk-cgroup.h | 22 ++++++++++++++++ > > include/linux/fs.h | 4 +++ > > mm/page-writeback.c | 1 + > > 6 files changed, 124 insertions(+), 3 deletions(-) > > > > diff --git a/block/blk-cgroup.c b/block/blk-cgroup.c > > index 4305e78d1bb2..7d3b26ba4575 100644 > > --- a/block/blk-cgroup.c > > +++ b/block/blk-cgroup.c > > @@ -1480,6 +1480,53 @@ void blkcg_stop_wb_wait_on_bdi(struct backing_dev_info *bdi) > > spin_unlock(&blkcg_wb_sleeper_lock); > > rcu_read_unlock(); > > } > > + > > +/** > > + * blkcg_set_mapping_dirty - set owner of a dirty mapping > > + * @mapping: target address space > > + * > > + * Set the current blkcg as the owner of the address space @mapping (the first > > + * blkcg that dirties @mapping becomes the owner). > > + */ > > +void blkcg_set_mapping_dirty(struct address_space *mapping) > > +{ > > + struct blkcg *curr_blkcg, *blkcg; > > + > > + if (mapping_tagged(mapping, PAGECACHE_TAG_WRITEBACK) || > > + mapping_tagged(mapping, PAGECACHE_TAG_DIRTY)) > > + return; > > + > > + rcu_read_lock(); > > + curr_blkcg = blkcg_from_current(); > > + blkcg = blkcg_from_mapping(mapping); > > + if (curr_blkcg != blkcg) { > > + if (blkcg) > > + css_put(&blkcg->css); > > + css_get(&curr_blkcg->css); > > + rcu_assign_pointer(mapping->i_blkcg, curr_blkcg); > > + } > > + rcu_read_unlock(); > > +} > > + > > +/** > > + * blkcg_set_mapping_clean - clear the owner of a dirty mapping > > + * @mapping: target address space > > + * > > + * Unset the owner of @mapping when it becomes clean. > > + */ > > + > > +void blkcg_set_mapping_clean(struct address_space *mapping) > > +{ > > + struct blkcg *blkcg; > > + > > + rcu_read_lock(); > > + blkcg = rcu_dereference(mapping->i_blkcg); > > + if (blkcg) { > > + css_put(&blkcg->css); > > + RCU_INIT_POINTER(mapping->i_blkcg, NULL); > > + } > > + rcu_read_unlock(); > > +} > > #endif > > > > Why do we need this? We already have the inode_attach_wb(), which has the > blkcg_css embedded in it for whoever dirtied the inode first. Can we not just > use that? Thanks, > > Josef I'm realizing only now that inode_attach_wb() also has blkcg embedded in addition to the memcg. I think I can use that and drop these blkcg_set_mapping_dirty/clean().. Thanks, -Andrea
diff --git a/block/blk-cgroup.c b/block/blk-cgroup.c index 4305e78d1bb2..7d3b26ba4575 100644 --- a/block/blk-cgroup.c +++ b/block/blk-cgroup.c @@ -1480,6 +1480,53 @@ void blkcg_stop_wb_wait_on_bdi(struct backing_dev_info *bdi) spin_unlock(&blkcg_wb_sleeper_lock); rcu_read_unlock(); } + +/** + * blkcg_set_mapping_dirty - set owner of a dirty mapping + * @mapping: target address space + * + * Set the current blkcg as the owner of the address space @mapping (the first + * blkcg that dirties @mapping becomes the owner). + */ +void blkcg_set_mapping_dirty(struct address_space *mapping) +{ + struct blkcg *curr_blkcg, *blkcg; + + if (mapping_tagged(mapping, PAGECACHE_TAG_WRITEBACK) || + mapping_tagged(mapping, PAGECACHE_TAG_DIRTY)) + return; + + rcu_read_lock(); + curr_blkcg = blkcg_from_current(); + blkcg = blkcg_from_mapping(mapping); + if (curr_blkcg != blkcg) { + if (blkcg) + css_put(&blkcg->css); + css_get(&curr_blkcg->css); + rcu_assign_pointer(mapping->i_blkcg, curr_blkcg); + } + rcu_read_unlock(); +} + +/** + * blkcg_set_mapping_clean - clear the owner of a dirty mapping + * @mapping: target address space + * + * Unset the owner of @mapping when it becomes clean. + */ + +void blkcg_set_mapping_clean(struct address_space *mapping) +{ + struct blkcg *blkcg; + + rcu_read_lock(); + blkcg = rcu_dereference(mapping->i_blkcg); + if (blkcg) { + css_put(&blkcg->css); + RCU_INIT_POINTER(mapping->i_blkcg, NULL); + } + rcu_read_unlock(); +} #endif /** diff --git a/fs/fs-writeback.c b/fs/fs-writeback.c index 77c039a0ec25..d003d0593f41 100644 --- a/fs/fs-writeback.c +++ b/fs/fs-writeback.c @@ -58,6 +58,9 @@ struct wb_writeback_work { struct list_head list; /* pending work list */ struct wb_completion *done; /* set if the caller waits */ +#ifdef CONFIG_CGROUP_WRITEBACK + struct blkcg *blkcg; +#endif }; /* @@ -916,6 +919,29 @@ static int __init cgroup_writeback_init(void) } fs_initcall(cgroup_writeback_init); +static void blkcg_set_sync_domain(struct wb_writeback_work *work) +{ + rcu_read_lock(); + work->blkcg = blkcg_from_current(); + rcu_read_unlock(); +} + +static bool blkcg_same_sync_domain(struct wb_writeback_work *work, + struct address_space *mapping) +{ + struct blkcg *blkcg; + + if (!work->blkcg || work->blkcg == &blkcg_root) + return true; + if (!test_bit(BLKCG_SYNC_ISOLATION, &work->blkcg->flags)) + return true; + rcu_read_lock(); + blkcg = blkcg_from_mapping(mapping); + rcu_read_unlock(); + + return blkcg == work->blkcg; +} + #else /* CONFIG_CGROUP_WRITEBACK */ static void bdi_down_write_wb_switch_rwsem(struct backing_dev_info *bdi) { } @@ -959,6 +985,15 @@ static void bdi_split_work_to_wbs(struct backing_dev_info *bdi, } } +static void blkcg_set_sync_domain(struct wb_writeback_work *work) +{ +} + +static bool blkcg_same_sync_domain(struct wb_writeback_work *work, + struct address_space *mapping) +{ + return true; +} #endif /* CONFIG_CGROUP_WRITEBACK */ /* @@ -1131,7 +1166,7 @@ static int move_expired_inodes(struct list_head *delaying_queue, LIST_HEAD(tmp); struct list_head *pos, *node; struct super_block *sb = NULL; - struct inode *inode; + struct inode *inode, *next; int do_sb_sort = 0; int moved = 0; @@ -1141,11 +1176,12 @@ static int move_expired_inodes(struct list_head *delaying_queue, expire_time = jiffies - (dirtytime_expire_interval * HZ); older_than_this = &expire_time; } - while (!list_empty(delaying_queue)) { - inode = wb_inode(delaying_queue->prev); + list_for_each_entry_safe(inode, next, delaying_queue, i_io_list) { if (older_than_this && inode_dirtied_after(inode, *older_than_this)) break; + if (!blkcg_same_sync_domain(work, inode->i_mapping)) + continue; list_move(&inode->i_io_list, &tmp); moved++; if (flags & EXPIRE_DIRTY_ATIME) @@ -1560,6 +1596,15 @@ static long writeback_sb_inodes(struct super_block *sb, break; } + /* + * Only write out inodes that belong to the blkcg that issued + * the sync(). + */ + if (!blkcg_same_sync_domain(work, inode->i_mapping)) { + redirty_tail(inode, wb); + continue; + } + /* * Don't bother with new inodes or inodes being freed, first * kind does not need periodic writeout yet, and for the latter @@ -2447,6 +2492,7 @@ void sync_inodes_sb(struct super_block *sb) return; WARN_ON(!rwsem_is_locked(&sb->s_umount)); + blkcg_set_sync_domain(&work); blkcg_start_wb_wait_on_bdi(bdi); /* protect against inode wb switch, see inode_switch_wbs_work_fn() */ diff --git a/fs/inode.c b/fs/inode.c index e9d97add2b36..b9659aaa8546 100644 --- a/fs/inode.c +++ b/fs/inode.c @@ -564,6 +564,7 @@ static void evict(struct inode *inode) bd_forget(inode); if (S_ISCHR(inode->i_mode) && inode->i_cdev) cd_forget(inode); + blkcg_set_mapping_clean(&inode->i_data); remove_inode_hash(inode); diff --git a/include/linux/blk-cgroup.h b/include/linux/blk-cgroup.h index 6ac5aa049334..a2bcc83c8c3e 100644 --- a/include/linux/blk-cgroup.h +++ b/include/linux/blk-cgroup.h @@ -441,6 +441,15 @@ extern void blkcg_destroy_blkgs(struct blkcg *blkcg); #ifdef CONFIG_CGROUP_WRITEBACK +static inline struct blkcg *blkcg_from_mapping(struct address_space *mapping) +{ + WARN_ON_ONCE(!rcu_read_lock_held()); + return rcu_dereference(mapping->i_blkcg); +} + +void blkcg_set_mapping_dirty(struct address_space *mapping); +void blkcg_set_mapping_clean(struct address_space *mapping); + /** * blkcg_cgwb_get - get a reference for blkcg->cgwb_list * @blkcg: blkcg of interest @@ -474,6 +483,19 @@ void blkcg_stop_wb_wait_on_bdi(struct backing_dev_info *bdi); #else +static inline struct blkcg *blkcg_from_mapping(struct address_space *mapping) +{ + return NULL; +} + +static inline void blkcg_set_mapping_dirty(struct address_space *mapping) +{ +} + +static inline void blkcg_set_mapping_clean(struct address_space *mapping) +{ +} + static inline void blkcg_cgwb_get(struct blkcg *blkcg) { } static inline void blkcg_cgwb_put(struct blkcg *blkcg) diff --git a/include/linux/fs.h b/include/linux/fs.h index 08f26046233e..19e99b4a9fa2 100644 --- a/include/linux/fs.h +++ b/include/linux/fs.h @@ -420,6 +420,7 @@ int pagecache_write_end(struct file *, struct address_space *mapping, * @nrpages: Number of page entries, protected by the i_pages lock. * @nrexceptional: Shadow or DAX entries, protected by the i_pages lock. * @writeback_index: Writeback starts here. + * @i_blkcg: blkcg owner (that dirtied the address_space) * @a_ops: Methods. * @flags: Error bits and flags (AS_*). * @wb_err: The most recent error which has occurred. @@ -438,6 +439,9 @@ struct address_space { unsigned long nrexceptional; pgoff_t writeback_index; const struct address_space_operations *a_ops; +#ifdef CONFIG_CGROUP_WRITEBACK + struct blkcg __rcu *i_blkcg; +#endif unsigned long flags; errseq_t wb_err; spinlock_t private_lock; diff --git a/mm/page-writeback.c b/mm/page-writeback.c index 9f61dfec6a1f..e16574f946a7 100644 --- a/mm/page-writeback.c +++ b/mm/page-writeback.c @@ -2418,6 +2418,7 @@ void account_page_dirtied(struct page *page, struct address_space *mapping) inode_attach_wb(inode, page); wb = inode_to_wb(inode); + blkcg_set_mapping_dirty(mapping); __inc_lruvec_page_state(page, NR_FILE_DIRTY); __inc_zone_page_state(page, NR_ZONE_WRITE_PENDING); __inc_node_page_state(page, NR_DIRTIED);
Keep track of the inodes that have been dirtied by each blkcg cgroup and make sure that a blkcg issuing a sync() can trigger the writeback + wait of only those pages that belong to the cgroup itself. This behavior is applied only when io.sync_isolation is enabled in the cgroup, otherwise the old behavior is applied: sync() triggers the writeback of any dirty page. Signed-off-by: Andrea Righi <andrea.righi@canonical.com> --- block/blk-cgroup.c | 47 ++++++++++++++++++++++++++++++++++ fs/fs-writeback.c | 52 +++++++++++++++++++++++++++++++++++--- fs/inode.c | 1 + include/linux/blk-cgroup.h | 22 ++++++++++++++++ include/linux/fs.h | 4 +++ mm/page-writeback.c | 1 + 6 files changed, 124 insertions(+), 3 deletions(-)