diff options
| -rw-r--r-- | fs/fs-writeback.c | 106 | ||||
| -rw-r--r-- | include/linux/backing-dev-defs.h | 18 |
2 files changed, 80 insertions, 44 deletions
diff --git a/fs/fs-writeback.c b/fs/fs-writeback.c index 5520a6b5cc4d..737ac27adb77 100644 --- a/fs/fs-writeback.c +++ b/fs/fs-writeback.c @@ -335,10 +335,18 @@ static struct bdi_writeback *inode_to_wb_and_lock_list(struct inode *inode) } struct inode_switch_wbs_context { - struct inode *inode; - struct bdi_writeback *new_wb; - struct rcu_work work; + + /* + * Multiple inodes can be switched at once. The switching procedure + * consists of two parts, separated by a RCU grace period. To make + * sure that the second part is executed for each inode gone through + * the first part, all inode pointers are placed into a NULL-terminated + * array embedded into struct inode_switch_wbs_context. Otherwise + * an inode could be left in a non-consistent state. + */ + struct bdi_writeback *new_wb; + struct inode *inodes[]; }; static void bdi_down_write_wb_switch_rwsem(struct backing_dev_info *bdi) @@ -351,39 +359,15 @@ static void bdi_up_write_wb_switch_rwsem(struct backing_dev_info *bdi) up_write(&bdi->wb_switch_rwsem); } -static void inode_do_switch_wbs(struct inode *inode, +static bool inode_do_switch_wbs(struct inode *inode, + struct bdi_writeback *old_wb, struct bdi_writeback *new_wb) { - struct backing_dev_info *bdi = inode_to_bdi(inode); struct address_space *mapping = inode->i_mapping; - struct bdi_writeback *old_wb = inode->i_wb; XA_STATE(xas, &mapping->i_pages, 0); struct page *page; bool switched = false; - /* - * If @inode switches cgwb membership while sync_inodes_sb() is - * being issued, sync_inodes_sb() might miss it. Synchronize. - */ - down_read(&bdi->wb_switch_rwsem); - - /* - * By the time control reaches here, RCU grace period has passed - * since I_WB_SWITCH assertion and all wb stat update transactions - * between unlocked_inode_to_wb_begin/end() are guaranteed to be - * synchronizing against the i_pages lock. - * - * Grabbing old_wb->list_lock, inode->i_lock and the i_pages lock - * gives us exclusion against all wb related operations on @inode - * including IO list manipulations and stat updates. - */ - if (old_wb < new_wb) { - spin_lock(&old_wb->list_lock); - spin_lock_nested(&new_wb->list_lock, SINGLE_DEPTH_NESTING); - } else { - spin_lock(&new_wb->list_lock); - spin_lock_nested(&old_wb->list_lock, SINGLE_DEPTH_NESTING); - } spin_lock(&inode->i_lock); xa_lock_irq(&mapping->i_pages); @@ -458,25 +442,63 @@ skip_switch: xa_unlock_irq(&mapping->i_pages); spin_unlock(&inode->i_lock); - spin_unlock(&new_wb->list_lock); - spin_unlock(&old_wb->list_lock); - - up_read(&bdi->wb_switch_rwsem); - if (switched) { - wb_wakeup(new_wb); - wb_put(old_wb); - } + return switched; } static void inode_switch_wbs_work_fn(struct work_struct *work) { struct inode_switch_wbs_context *isw = container_of(to_rcu_work(work), struct inode_switch_wbs_context, work); + struct backing_dev_info *bdi = inode_to_bdi(isw->inodes[0]); + struct bdi_writeback *old_wb = isw->inodes[0]->i_wb; + struct bdi_writeback *new_wb = isw->new_wb; + unsigned long nr_switched = 0; + struct inode **inodep; + + /* + * If @inode switches cgwb membership while sync_inodes_sb() is + * being issued, sync_inodes_sb() might miss it. Synchronize. + */ + down_read(&bdi->wb_switch_rwsem); + + /* + * By the time control reaches here, RCU grace period has passed + * since I_WB_SWITCH assertion and all wb stat update transactions + * between unlocked_inode_to_wb_begin/end() are guaranteed to be + * synchronizing against the i_pages lock. + * + * Grabbing old_wb->list_lock, inode->i_lock and the i_pages lock + * gives us exclusion against all wb related operations on @inode + * including IO list manipulations and stat updates. + */ + if (old_wb < new_wb) { + spin_lock(&old_wb->list_lock); + spin_lock_nested(&new_wb->list_lock, SINGLE_DEPTH_NESTING); + } else { + spin_lock(&new_wb->list_lock); + spin_lock_nested(&old_wb->list_lock, SINGLE_DEPTH_NESTING); + } + + for (inodep = isw->inodes; *inodep; inodep++) { + WARN_ON_ONCE((*inodep)->i_wb != old_wb); + if (inode_do_switch_wbs(*inodep, old_wb, new_wb)) + nr_switched++; + } + + spin_unlock(&new_wb->list_lock); + spin_unlock(&old_wb->list_lock); + + up_read(&bdi->wb_switch_rwsem); + + if (nr_switched) { + wb_wakeup(new_wb); + wb_put_many(old_wb, nr_switched); + } - inode_do_switch_wbs(isw->inode, isw->new_wb); - wb_put(isw->new_wb); - iput(isw->inode); + for (inodep = isw->inodes; *inodep; inodep++) + iput(*inodep); + wb_put(new_wb); kfree(isw); atomic_dec(&isw_nr_in_flight); } @@ -503,7 +525,7 @@ static void inode_switch_wbs(struct inode *inode, int new_wb_id) if (atomic_read(&isw_nr_in_flight) > WB_FRN_MAX_IN_FLIGHT) return; - isw = kzalloc(sizeof(*isw), GFP_ATOMIC); + isw = kzalloc(sizeof(*isw) + 2 * sizeof(struct inode *), GFP_ATOMIC); if (!isw) return; @@ -530,7 +552,7 @@ static void inode_switch_wbs(struct inode *inode, int new_wb_id) __iget(inode); spin_unlock(&inode->i_lock); - isw->inode = inode; + isw->inodes[0] = inode; /* * In addition to synchronizing among switchers, I_WB_SWITCH tells diff --git a/include/linux/backing-dev-defs.h b/include/linux/backing-dev-defs.h index e5dc238ebe4f..63f52ad2ce7a 100644 --- a/include/linux/backing-dev-defs.h +++ b/include/linux/backing-dev-defs.h @@ -240,8 +240,9 @@ static inline void wb_get(struct bdi_writeback *wb) /** * wb_put - decrement a wb's refcount * @wb: bdi_writeback to put + * @nr: number of references to put */ -static inline void wb_put(struct bdi_writeback *wb) +static inline void wb_put_many(struct bdi_writeback *wb, unsigned long nr) { if (WARN_ON_ONCE(!wb->bdi)) { /* @@ -252,7 +253,16 @@ static inline void wb_put(struct bdi_writeback *wb) } if (wb != &wb->bdi->wb) - percpu_ref_put(&wb->refcnt); + percpu_ref_put_many(&wb->refcnt, nr); +} + +/** + * wb_put - decrement a wb's refcount + * @wb: bdi_writeback to put + */ +static inline void wb_put(struct bdi_writeback *wb) +{ + wb_put_many(wb, 1); } /** @@ -281,6 +291,10 @@ static inline void wb_put(struct bdi_writeback *wb) { } +static inline void wb_put_many(struct bdi_writeback *wb, unsigned long nr) +{ +} + static inline bool wb_dying(struct bdi_writeback *wb) { return false; |