From d8a8559cd7a9ccac98d5f6f13297a2ff68a43627 Mon Sep 17 00:00:00 2001 From: Jens Axboe Date: Wed, 2 Sep 2009 12:34:32 +0200 Subject: writeback: get rid of generic_sync_sb_inodes() export This adds two new exported functions: - writeback_inodes_sb(), which only attempts to writeback dirty inodes on this super_block, for WB_SYNC_NONE writeout. - sync_inodes_sb(), which writes out all dirty inodes on this super_block and also waits for the IO to complete. Acked-by: Jan Kara Signed-off-by: Jens Axboe --- include/linux/fs.h | 2 -- include/linux/writeback.h | 3 ++- 2 files changed, 2 insertions(+), 3 deletions(-) (limited to 'include') diff --git a/include/linux/fs.h b/include/linux/fs.h index c1f993515f51..46ff7dd6e164 100644 --- a/include/linux/fs.h +++ b/include/linux/fs.h @@ -2071,8 +2071,6 @@ static inline void invalidate_remote_inode(struct inode *inode) extern int invalidate_inode_pages2(struct address_space *mapping); extern int invalidate_inode_pages2_range(struct address_space *mapping, pgoff_t start, pgoff_t end); -extern void generic_sync_sb_inodes(struct super_block *sb, - struct writeback_control *wbc); extern int write_inode_now(struct inode *, int); extern int filemap_fdatawrite(struct address_space *); extern int filemap_flush(struct address_space *); diff --git a/include/linux/writeback.h b/include/linux/writeback.h index 3224820c8514..07039299603d 100644 --- a/include/linux/writeback.h +++ b/include/linux/writeback.h @@ -78,7 +78,8 @@ struct writeback_control { */ void writeback_inodes(struct writeback_control *wbc); int inode_wait(void *); -void sync_inodes_sb(struct super_block *, int wait); +long writeback_inodes_sb(struct super_block *); +long sync_inodes_sb(struct super_block *); /* writeback.h requires fs.h; it, too, is not included from here. */ static inline void wait_on_inode(struct inode *inode) -- cgit v1.2.3-58-ga151 From 66f3b8e2e103a0b93b945764d98e9ba46cb926dd Mon Sep 17 00:00:00 2001 From: Jens Axboe Date: Wed, 2 Sep 2009 09:19:46 +0200 Subject: writeback: move dirty inodes from super_block to backing_dev_info This is a first step at introducing per-bdi flusher threads. We should have no change in behaviour, although sb_has_dirty_inodes() is now ridiculously expensive, as there's no easy way to answer that question. Not a huge problem, since it'll be deleted in subsequent patches. Signed-off-by: Jens Axboe --- fs/fs-writeback.c | 197 ++++++++++++++++++++++++++++---------------- fs/super.c | 3 - include/linux/backing-dev.h | 9 ++ include/linux/fs.h | 5 +- mm/backing-dev.c | 24 ++++++ mm/page-writeback.c | 11 +-- 6 files changed, 165 insertions(+), 84 deletions(-) (limited to 'include') diff --git a/fs/fs-writeback.c b/fs/fs-writeback.c index 271e5f44e871..45ad4bb700e6 100644 --- a/fs/fs-writeback.c +++ b/fs/fs-writeback.c @@ -25,6 +25,7 @@ #include #include "internal.h" +#define inode_to_bdi(inode) ((inode)->i_mapping->backing_dev_info) /** * writeback_acquire - attempt to get exclusive writeback access to a device @@ -165,12 +166,13 @@ void __mark_inode_dirty(struct inode *inode, int flags) goto out; /* - * If the inode was already on s_dirty/s_io/s_more_io, don't - * reposition it (that would break s_dirty time-ordering). + * If the inode was already on b_dirty/b_io/b_more_io, don't + * reposition it (that would break b_dirty time-ordering). */ if (!was_dirty) { inode->dirtied_when = jiffies; - list_move(&inode->i_list, &sb->s_dirty); + list_move(&inode->i_list, + &inode_to_bdi(inode)->b_dirty); } } out: @@ -191,31 +193,30 @@ static int write_inode(struct inode *inode, int sync) * furthest end of its superblock's dirty-inode list. * * Before stamping the inode's ->dirtied_when, we check to see whether it is - * already the most-recently-dirtied inode on the s_dirty list. If that is + * already the most-recently-dirtied inode on the b_dirty list. If that is * the case then the inode must have been redirtied while it was being written * out and we don't reset its dirtied_when. */ static void redirty_tail(struct inode *inode) { - struct super_block *sb = inode->i_sb; + struct backing_dev_info *bdi = inode_to_bdi(inode); - if (!list_empty(&sb->s_dirty)) { - struct inode *tail_inode; + if (!list_empty(&bdi->b_dirty)) { + struct inode *tail; - tail_inode = list_entry(sb->s_dirty.next, struct inode, i_list); - if (time_before(inode->dirtied_when, - tail_inode->dirtied_when)) + tail = list_entry(bdi->b_dirty.next, struct inode, i_list); + if (time_before(inode->dirtied_when, tail->dirtied_when)) inode->dirtied_when = jiffies; } - list_move(&inode->i_list, &sb->s_dirty); + list_move(&inode->i_list, &bdi->b_dirty); } /* - * requeue inode for re-scanning after sb->s_io list is exhausted. + * requeue inode for re-scanning after bdi->b_io list is exhausted. */ static void requeue_io(struct inode *inode) { - list_move(&inode->i_list, &inode->i_sb->s_more_io); + list_move(&inode->i_list, &inode_to_bdi(inode)->b_more_io); } static void inode_sync_complete(struct inode *inode) @@ -262,18 +263,50 @@ static void move_expired_inodes(struct list_head *delaying_queue, /* * Queue all expired dirty inodes for io, eldest first. */ -static void queue_io(struct super_block *sb, - unsigned long *older_than_this) +static void queue_io(struct backing_dev_info *bdi, + unsigned long *older_than_this) +{ + list_splice_init(&bdi->b_more_io, bdi->b_io.prev); + move_expired_inodes(&bdi->b_dirty, &bdi->b_io, older_than_this); +} + +static int sb_on_inode_list(struct super_block *sb, struct list_head *list) { - list_splice_init(&sb->s_more_io, sb->s_io.prev); - move_expired_inodes(&sb->s_dirty, &sb->s_io, older_than_this); + struct inode *inode; + int ret = 0; + + spin_lock(&inode_lock); + list_for_each_entry(inode, list, i_list) { + if (inode->i_sb == sb) { + ret = 1; + break; + } + } + spin_unlock(&inode_lock); + return ret; } int sb_has_dirty_inodes(struct super_block *sb) { - return !list_empty(&sb->s_dirty) || - !list_empty(&sb->s_io) || - !list_empty(&sb->s_more_io); + struct backing_dev_info *bdi; + int ret = 0; + + /* + * This is REALLY expensive right now, but it'll go away + * when the bdi writeback is introduced + */ + mutex_lock(&bdi_lock); + list_for_each_entry(bdi, &bdi_list, bdi_list) { + if (sb_on_inode_list(sb, &bdi->b_dirty) || + sb_on_inode_list(sb, &bdi->b_io) || + sb_on_inode_list(sb, &bdi->b_more_io)) { + ret = 1; + break; + } + } + mutex_unlock(&bdi_lock); + + return ret; } EXPORT_SYMBOL(sb_has_dirty_inodes); @@ -322,11 +355,11 @@ writeback_single_inode(struct inode *inode, struct writeback_control *wbc) if (inode->i_state & I_SYNC) { /* * If this inode is locked for writeback and we are not doing - * writeback-for-data-integrity, move it to s_more_io so that + * writeback-for-data-integrity, move it to b_more_io so that * writeback can proceed with the other inodes on s_io. * * We'll have another go at writing back this inode when we - * completed a full scan of s_io. + * completed a full scan of b_io. */ if (!wait) { requeue_io(inode); @@ -371,11 +404,11 @@ writeback_single_inode(struct inode *inode, struct writeback_control *wbc) /* * We didn't write back all the pages. nfs_writepages() * sometimes bales out without doing anything. Redirty - * the inode; Move it from s_io onto s_more_io/s_dirty. + * the inode; Move it from b_io onto b_more_io/b_dirty. */ /* * akpm: if the caller was the kupdate function we put - * this inode at the head of s_dirty so it gets first + * this inode at the head of b_dirty so it gets first * consideration. Otherwise, move it to the tail, for * the reasons described there. I'm not really sure * how much sense this makes. Presumably I had a good @@ -385,7 +418,7 @@ writeback_single_inode(struct inode *inode, struct writeback_control *wbc) if (wbc->for_kupdate) { /* * For the kupdate function we move the inode - * to s_more_io so it will get more writeout as + * to b_more_io so it will get more writeout as * soon as the queue becomes uncongested. */ inode->i_state |= I_DIRTY_PAGES; @@ -433,51 +466,34 @@ writeback_single_inode(struct inode *inode, struct writeback_control *wbc) return ret; } -/* - * Write out a superblock's list of dirty inodes. A wait will be performed - * upon no inodes, all inodes or the final one, depending upon sync_mode. - * - * If older_than_this is non-NULL, then only write out inodes which - * had their first dirtying at a time earlier than *older_than_this. - * - * If we're a pdflush thread, then implement pdflush collision avoidance - * against the entire list. - * - * If `bdi' is non-zero then we're being asked to writeback a specific queue. - * This function assumes that the blockdev superblock's inodes are backed by - * a variety of queues, so all inodes are searched. For other superblocks, - * assume that all inodes are backed by the same queue. - * - * FIXME: this linear search could get expensive with many fileystems. But - * how to fix? We need to go from an address_space to all inodes which share - * a queue with that address_space. (Easy: have a global "dirty superblocks" - * list). - * - * The inodes to be written are parked on sb->s_io. They are moved back onto - * sb->s_dirty as they are selected for writing. This way, none can be missed - * on the writer throttling path, and we get decent balancing between many - * throttled threads: we don't want them all piling up on inode_sync_wait. - */ -static void generic_sync_sb_inodes(struct super_block *sb, - struct writeback_control *wbc) +static void generic_sync_bdi_inodes(struct backing_dev_info *bdi, + struct writeback_control *wbc, + struct super_block *sb) { + const int is_blkdev_sb = sb_is_blkdev_sb(sb); const unsigned long start = jiffies; /* livelock avoidance */ - int sync = wbc->sync_mode == WB_SYNC_ALL; spin_lock(&inode_lock); - if (!wbc->for_kupdate || list_empty(&sb->s_io)) - queue_io(sb, wbc->older_than_this); - while (!list_empty(&sb->s_io)) { - struct inode *inode = list_entry(sb->s_io.prev, + if (!wbc->for_kupdate || list_empty(&bdi->b_io)) + queue_io(bdi, wbc->older_than_this); + + while (!list_empty(&bdi->b_io)) { + struct inode *inode = list_entry(bdi->b_io.prev, struct inode, i_list); - struct address_space *mapping = inode->i_mapping; - struct backing_dev_info *bdi = mapping->backing_dev_info; long pages_skipped; + /* + * super block given and doesn't match, skip this inode + */ + if (sb && sb != inode->i_sb) { + redirty_tail(inode); + continue; + } + if (!bdi_cap_writeback_dirty(bdi)) { redirty_tail(inode); - if (sb_is_blkdev_sb(sb)) { + if (is_blkdev_sb) { /* * Dirty memory-backed blockdev: the ramdisk * driver does this. Skip just this inode @@ -499,14 +515,14 @@ static void generic_sync_sb_inodes(struct super_block *sb, if (wbc->nonblocking && bdi_write_congested(bdi)) { wbc->encountered_congestion = 1; - if (!sb_is_blkdev_sb(sb)) + if (!is_blkdev_sb) break; /* Skip a congested fs */ requeue_io(inode); continue; /* Skip a congested blockdev */ } if (wbc->bdi && bdi != wbc->bdi) { - if (!sb_is_blkdev_sb(sb)) + if (!is_blkdev_sb) break; /* fs has the wrong queue */ requeue_io(inode); continue; /* blockdev has wrong queue */ @@ -544,13 +560,57 @@ static void generic_sync_sb_inodes(struct super_block *sb, wbc->more_io = 1; break; } - if (!list_empty(&sb->s_more_io)) + if (!list_empty(&bdi->b_more_io)) wbc->more_io = 1; } - if (sync) { + spin_unlock(&inode_lock); + /* Leave any unwritten inodes on b_io */ +} + +/* + * Write out a superblock's list of dirty inodes. A wait will be performed + * upon no inodes, all inodes or the final one, depending upon sync_mode. + * + * If older_than_this is non-NULL, then only write out inodes which + * had their first dirtying at a time earlier than *older_than_this. + * + * If we're a pdlfush thread, then implement pdflush collision avoidance + * against the entire list. + * + * If `bdi' is non-zero then we're being asked to writeback a specific queue. + * This function assumes that the blockdev superblock's inodes are backed by + * a variety of queues, so all inodes are searched. For other superblocks, + * assume that all inodes are backed by the same queue. + * + * FIXME: this linear search could get expensive with many fileystems. But + * how to fix? We need to go from an address_space to all inodes which share + * a queue with that address_space. (Easy: have a global "dirty superblocks" + * list). + * + * The inodes to be written are parked on bdi->b_io. They are moved back onto + * bdi->b_dirty as they are selected for writing. This way, none can be missed + * on the writer throttling path, and we get decent balancing between many + * throttled threads: we don't want them all piling up on inode_sync_wait. + */ +static void generic_sync_sb_inodes(struct super_block *sb, + struct writeback_control *wbc) +{ + struct backing_dev_info *bdi; + + if (!wbc->bdi) { + mutex_lock(&bdi_lock); + list_for_each_entry(bdi, &bdi_list, bdi_list) + generic_sync_bdi_inodes(bdi, wbc, sb); + mutex_unlock(&bdi_lock); + } else + generic_sync_bdi_inodes(wbc->bdi, wbc, sb); + + if (wbc->sync_mode == WB_SYNC_ALL) { struct inode *inode, *old_inode = NULL; + spin_lock(&inode_lock); + /* * Data integrity sync. Must wait for all pages under writeback, * because there may have been pages dirtied before our sync @@ -588,10 +648,7 @@ static void generic_sync_sb_inodes(struct super_block *sb, } spin_unlock(&inode_lock); iput(old_inode); - } else - spin_unlock(&inode_lock); - - return; /* Leave any unwritten inodes on s_io */ + } } /* @@ -599,8 +656,8 @@ static void generic_sync_sb_inodes(struct super_block *sb, * * Note: * We don't need to grab a reference to superblock here. If it has non-empty - * ->s_dirty it's hadn't been killed yet and kill_super() won't proceed - * past sync_inodes_sb() until the ->s_dirty/s_io/s_more_io lists are all + * ->b_dirty it's hadn't been killed yet and kill_super() won't proceed + * past sync_inodes_sb() until the ->b_dirty/b_io/b_more_io lists are all * empty. Since __sync_single_inode() regains inode_lock before it finally moves * inode from superblock lists we are OK. * diff --git a/fs/super.c b/fs/super.c index 2761d3e22ed9..0d22ce3be4aa 100644 --- a/fs/super.c +++ b/fs/super.c @@ -62,9 +62,6 @@ static struct super_block *alloc_super(struct file_system_type *type) s = NULL; goto out; } - INIT_LIST_HEAD(&s->s_dirty); - INIT_LIST_HEAD(&s->s_io); - INIT_LIST_HEAD(&s->s_more_io); INIT_LIST_HEAD(&s->s_files); INIT_LIST_HEAD(&s->s_instances); INIT_HLIST_HEAD(&s->s_anon); diff --git a/include/linux/backing-dev.h b/include/linux/backing-dev.h index 1d52425a6118..928cd5484f4d 100644 --- a/include/linux/backing-dev.h +++ b/include/linux/backing-dev.h @@ -40,6 +40,8 @@ enum bdi_stat_item { #define BDI_STAT_BATCH (8*(1+ilog2(nr_cpu_ids))) struct backing_dev_info { + struct list_head bdi_list; + unsigned long ra_pages; /* max readahead in PAGE_CACHE_SIZE units */ unsigned long state; /* Always use atomic bitops on this */ unsigned int capabilities; /* Device capabilities */ @@ -58,6 +60,10 @@ struct backing_dev_info { struct device *dev; + struct list_head b_dirty; /* dirty inodes */ + struct list_head b_io; /* parked for writeback */ + struct list_head b_more_io; /* parked for more writeback */ + #ifdef CONFIG_DEBUG_FS struct dentry *debug_dir; struct dentry *debug_stats; @@ -72,6 +78,9 @@ int bdi_register(struct backing_dev_info *bdi, struct device *parent, int bdi_register_dev(struct backing_dev_info *bdi, dev_t dev); void bdi_unregister(struct backing_dev_info *bdi); +extern struct mutex bdi_lock; +extern struct list_head bdi_list; + static inline void __add_bdi_stat(struct backing_dev_info *bdi, enum bdi_stat_item item, s64 amount) { diff --git a/include/linux/fs.h b/include/linux/fs.h index 46ff7dd6e164..56371be1be65 100644 --- a/include/linux/fs.h +++ b/include/linux/fs.h @@ -715,7 +715,7 @@ struct posix_acl; struct inode { struct hlist_node i_hash; - struct list_head i_list; + struct list_head i_list; /* backing dev IO list */ struct list_head i_sb_list; struct list_head i_dentry; unsigned long i_ino; @@ -1336,9 +1336,6 @@ struct super_block { struct xattr_handler **s_xattr; struct list_head s_inodes; /* all inodes */ - struct list_head s_dirty; /* dirty inodes */ - struct list_head s_io; /* parked for writeback */ - struct list_head s_more_io; /* parked for more writeback */ struct hlist_head s_anon; /* anonymous dentries for (nfs) exporting */ struct list_head s_files; /* s_dentry_lru and s_nr_dentry_unused are protected by dcache_lock */ diff --git a/mm/backing-dev.c b/mm/backing-dev.c index c86edd244294..6f163e0f0509 100644 --- a/mm/backing-dev.c +++ b/mm/backing-dev.c @@ -22,6 +22,8 @@ struct backing_dev_info default_backing_dev_info = { EXPORT_SYMBOL_GPL(default_backing_dev_info); static struct class *bdi_class; +DEFINE_MUTEX(bdi_lock); +LIST_HEAD(bdi_list); #ifdef CONFIG_DEBUG_FS #include @@ -211,6 +213,10 @@ int bdi_register(struct backing_dev_info *bdi, struct device *parent, goto exit; } + mutex_lock(&bdi_lock); + list_add_tail(&bdi->bdi_list, &bdi_list); + mutex_unlock(&bdi_lock); + bdi->dev = dev; bdi_debug_register(bdi, dev_name(dev)); @@ -225,9 +231,17 @@ int bdi_register_dev(struct backing_dev_info *bdi, dev_t dev) } EXPORT_SYMBOL(bdi_register_dev); +static void bdi_remove_from_list(struct backing_dev_info *bdi) +{ + mutex_lock(&bdi_lock); + list_del(&bdi->bdi_list); + mutex_unlock(&bdi_lock); +} + void bdi_unregister(struct backing_dev_info *bdi) { if (bdi->dev) { + bdi_remove_from_list(bdi); bdi_debug_unregister(bdi); device_unregister(bdi->dev); bdi->dev = NULL; @@ -245,6 +259,10 @@ int bdi_init(struct backing_dev_info *bdi) bdi->min_ratio = 0; bdi->max_ratio = 100; bdi->max_prop_frac = PROP_FRAC_BASE; + INIT_LIST_HEAD(&bdi->bdi_list); + INIT_LIST_HEAD(&bdi->b_io); + INIT_LIST_HEAD(&bdi->b_dirty); + INIT_LIST_HEAD(&bdi->b_more_io); for (i = 0; i < NR_BDI_STAT_ITEMS; i++) { err = percpu_counter_init(&bdi->bdi_stat[i], 0); @@ -259,6 +277,8 @@ int bdi_init(struct backing_dev_info *bdi) err: while (i--) percpu_counter_destroy(&bdi->bdi_stat[i]); + + bdi_remove_from_list(bdi); } return err; @@ -269,6 +289,10 @@ void bdi_destroy(struct backing_dev_info *bdi) { int i; + WARN_ON(!list_empty(&bdi->b_dirty)); + WARN_ON(!list_empty(&bdi->b_io)); + WARN_ON(!list_empty(&bdi->b_more_io)); + bdi_unregister(bdi); for (i = 0; i < NR_BDI_STAT_ITEMS; i++) diff --git a/mm/page-writeback.c b/mm/page-writeback.c index 81627ebcd313..f8341b6019bf 100644 --- a/mm/page-writeback.c +++ b/mm/page-writeback.c @@ -320,15 +320,13 @@ static void task_dirty_limit(struct task_struct *tsk, unsigned long *pdirty) /* * */ -static DEFINE_SPINLOCK(bdi_lock); static unsigned int bdi_min_ratio; int bdi_set_min_ratio(struct backing_dev_info *bdi, unsigned int min_ratio) { int ret = 0; - unsigned long flags; - spin_lock_irqsave(&bdi_lock, flags); + mutex_lock(&bdi_lock); if (min_ratio > bdi->max_ratio) { ret = -EINVAL; } else { @@ -340,27 +338,26 @@ int bdi_set_min_ratio(struct backing_dev_info *bdi, unsigned int min_ratio) ret = -EINVAL; } } - spin_unlock_irqrestore(&bdi_lock, flags); + mutex_unlock(&bdi_lock); return ret; } int bdi_set_max_ratio(struct backing_dev_info *bdi, unsigned max_ratio) { - unsigned long flags; int ret = 0; if (max_ratio > 100) return -EINVAL; - spin_lock_irqsave(&bdi_lock, flags); + mutex_lock(&bdi_lock); if (bdi->min_ratio > max_ratio) { ret = -EINVAL; } else { bdi->max_ratio = max_ratio; bdi->max_prop_frac = (PROP_FRAC_BASE * max_ratio) / 100; } - spin_unlock_irqrestore(&bdi_lock, flags); + mutex_unlock(&bdi_lock); return ret; } -- cgit v1.2.3-58-ga151 From 03ba3782e8dcc5b0e1efe440d33084f066e38cae Mon Sep 17 00:00:00 2001 From: Jens Axboe Date: Wed, 9 Sep 2009 09:08:54 +0200 Subject: writeback: switch to per-bdi threads for flushing data This gets rid of pdflush for bdi writeout and kupdated style cleaning. pdflush writeout suffers from lack of locality and also requires more threads to handle the same workload, since it has to work in a non-blocking fashion against each queue. This also introduces lumpy behaviour and potential request starvation, since pdflush can be starved for queue access if others are accessing it. A sample ffsb workload that does random writes to files is about 8% faster here on a simple SATA drive during the benchmark phase. File layout also seems a LOT more smooth in vmstat: r b swpd free buff cache si so bi bo in cs us sy id wa 0 1 0 608848 2652 375372 0 0 0 71024 604 24 1 10 48 42 0 1 0 549644 2712 433736 0 0 0 60692 505 27 1 8 48 44 1 0 0 476928 2784 505192 0 0 4 29540 553 24 0 9 53 37 0 1 0 457972 2808 524008 0 0 0 54876 331 16 0 4 38 58 0 1 0 366128 2928 614284 0 0 4 92168 710 58 0 13 53 34 0 1 0 295092 3000 684140 0 0 0 62924 572 23 0 9 53 37 0 1 0 236592 3064 741704 0 0 4 58256 523 17 0 8 48 44 0 1 0 165608 3132 811464 0 0 0 57460 560 21 0 8 54 38 0 1 0 102952 3200 873164 0 0 4 74748 540 29 1 10 48 41 0 1 0 48604 3252 926472 0 0 0 53248 469 29 0 7 47 45 where vanilla tends to fluctuate a lot in the creation phase: r b swpd free buff cache si so bi bo in cs us sy id wa 1 1 0 678716 5792 303380 0 0 0 74064 565 50 1 11 52 36 1 0 0 662488 5864 319396 0 0 4 352 302 329 0 2 47 51 0 1 0 599312 5924 381468 0 0 0 78164 516 55 0 9 51 40 0 1 0 519952 6008 459516 0 0 4 78156 622 56 1 11 52 37 1 1 0 436640 6092 541632 0 0 0 82244 622 54 0 11 48 41 0 1 0 436640 6092 541660 0 0 0 8 152 39 0 0 51 49 0 1 0 332224 6200 644252 0 0 4 102800 728 46 1 13 49 36 1 0 0 274492 6260 701056 0 0 4 12328 459 49 0 7 50 43 0 1 0 211220 6324 763356 0 0 0 106940 515 37 1 10 51 39 1 0 0 160412 6376 813468 0 0 0 8224 415 43 0 6 49 45 1 1 0 85980 6452 886556 0 0 4 113516 575 39 1 11 54 34 0 2 0 85968 6452 886620 0 0 0 1640 158 211 0 0 46 54 A 10 disk test with btrfs performs 26% faster with per-bdi flushing. A SSD based writeback test on XFS performs over 20% better as well, with the throughput being very stable around 1GB/sec, where pdflush only manages 750MB/sec and fluctuates wildly while doing so. Random buffered writes to many files behave a lot better as well, as does random mmap'ed writes. A separate thread is added to sync the super blocks. In the long term, adding sync_supers_bdi() functionality could get rid of this thread again. Signed-off-by: Jens Axboe --- fs/buffer.c | 2 +- fs/fs-writeback.c | 999 +++++++++++++++++++++++++++++++------------- fs/super.c | 2 +- fs/sync.c | 2 +- include/linux/backing-dev.h | 55 ++- include/linux/fs.h | 2 +- include/linux/writeback.h | 8 +- mm/backing-dev.c | 341 ++++++++++++++- mm/page-writeback.c | 179 ++------ mm/vmscan.c | 2 +- 10 files changed, 1120 insertions(+), 472 deletions(-) (limited to 'include') diff --git a/fs/buffer.c b/fs/buffer.c index 28f320fac4d4..90a98865b0cc 100644 --- a/fs/buffer.c +++ b/fs/buffer.c @@ -281,7 +281,7 @@ static void free_more_memory(void) struct zone *zone; int nid; - wakeup_pdflush(1024); + wakeup_flusher_threads(1024); yield(); for_each_online_node(nid) { diff --git a/fs/fs-writeback.c b/fs/fs-writeback.c index 45ad4bb700e6..7f6dae8aa47f 100644 --- a/fs/fs-writeback.c +++ b/fs/fs-writeback.c @@ -19,6 +19,8 @@ #include #include #include +#include +#include #include #include #include @@ -27,165 +29,208 @@ #define inode_to_bdi(inode) ((inode)->i_mapping->backing_dev_info) -/** - * writeback_acquire - attempt to get exclusive writeback access to a device - * @bdi: the device's backing_dev_info structure - * - * It is a waste of resources to have more than one pdflush thread blocked on - * a single request queue. Exclusion at the request_queue level is obtained - * via a flag in the request_queue's backing_dev_info.state. - * - * Non-request_queue-backed address_spaces will share default_backing_dev_info, - * unless they implement their own. Which is somewhat inefficient, as this - * may prevent concurrent writeback against multiple devices. +/* + * Work items for the bdi_writeback threads */ -static int writeback_acquire(struct backing_dev_info *bdi) +struct bdi_work { + struct list_head list; + struct list_head wait_list; + struct rcu_head rcu_head; + + unsigned long seen; + atomic_t pending; + + struct super_block *sb; + unsigned long nr_pages; + enum writeback_sync_modes sync_mode; + + unsigned long state; +}; + +enum { + WS_USED_B = 0, + WS_ONSTACK_B, +}; + +#define WS_USED (1 << WS_USED_B) +#define WS_ONSTACK (1 << WS_ONSTACK_B) + +static inline bool bdi_work_on_stack(struct bdi_work *work) +{ + return test_bit(WS_ONSTACK_B, &work->state); +} + +static inline void bdi_work_init(struct bdi_work *work, + struct writeback_control *wbc) +{ + INIT_RCU_HEAD(&work->rcu_head); + work->sb = wbc->sb; + work->nr_pages = wbc->nr_to_write; + work->sync_mode = wbc->sync_mode; + work->state = WS_USED; +} + +static inline void bdi_work_init_on_stack(struct bdi_work *work, + struct writeback_control *wbc) { - return !test_and_set_bit(BDI_pdflush, &bdi->state); + bdi_work_init(work, wbc); + work->state |= WS_ONSTACK; } /** * writeback_in_progress - determine whether there is writeback in progress * @bdi: the device's backing_dev_info structure. * - * Determine whether there is writeback in progress against a backing device. + * Determine whether there is writeback waiting to be handled against a + * backing device. */ int writeback_in_progress(struct backing_dev_info *bdi) { - return test_bit(BDI_pdflush, &bdi->state); + return !list_empty(&bdi->work_list); } -/** - * writeback_release - relinquish exclusive writeback access against a device. - * @bdi: the device's backing_dev_info structure - */ -static void writeback_release(struct backing_dev_info *bdi) +static void bdi_work_clear(struct bdi_work *work) { - BUG_ON(!writeback_in_progress(bdi)); - clear_bit(BDI_pdflush, &bdi->state); + clear_bit(WS_USED_B, &work->state); + smp_mb__after_clear_bit(); + wake_up_bit(&work->state, WS_USED_B); } -static noinline void block_dump___mark_inode_dirty(struct inode *inode) +static void bdi_work_free(struct rcu_head *head) { - if (inode->i_ino || strcmp(inode->i_sb->s_id, "bdev")) { - struct dentry *dentry; - const char *name = "?"; + struct bdi_work *work = container_of(head, struct bdi_work, rcu_head); - dentry = d_find_alias(inode); - if (dentry) { - spin_lock(&dentry->d_lock); - name = (const char *) dentry->d_name.name; - } - printk(KERN_DEBUG - "%s(%d): dirtied inode %lu (%s) on %s\n", - current->comm, task_pid_nr(current), inode->i_ino, - name, inode->i_sb->s_id); - if (dentry) { - spin_unlock(&dentry->d_lock); - dput(dentry); - } - } + if (!bdi_work_on_stack(work)) + kfree(work); + else + bdi_work_clear(work); } -/** - * __mark_inode_dirty - internal function - * @inode: inode to mark - * @flags: what kind of dirty (i.e. I_DIRTY_SYNC) - * Mark an inode as dirty. Callers should use mark_inode_dirty or - * mark_inode_dirty_sync. - * - * Put the inode on the super block's dirty list. - * - * CAREFUL! We mark it dirty unconditionally, but move it onto the - * dirty list only if it is hashed or if it refers to a blockdev. - * If it was not hashed, it will never be added to the dirty list - * even if it is later hashed, as it will have been marked dirty already. - * - * In short, make sure you hash any inodes _before_ you start marking - * them dirty. - * - * This function *must* be atomic for the I_DIRTY_PAGES case - - * set_page_dirty() is called under spinlock in several places. - * - * Note that for blockdevs, inode->dirtied_when represents the dirtying time of - * the block-special inode (/dev/hda1) itself. And the ->dirtied_when field of - * the kernel-internal blockdev inode represents the dirtying time of the - * blockdev's pages. This is why for I_DIRTY_PAGES we always use - * page->mapping->host, so the page-dirtying time is recorded in the internal - * blockdev inode. - */ -void __mark_inode_dirty(struct inode *inode, int flags) +static void wb_work_complete(struct bdi_work *work) { - struct super_block *sb = inode->i_sb; + const enum writeback_sync_modes sync_mode = work->sync_mode; /* - * Don't do this for I_DIRTY_PAGES - that doesn't actually - * dirty the inode itself + * For allocated work, we can clear the done/seen bit right here. + * For on-stack work, we need to postpone both the clear and free + * to after the RCU grace period, since the stack could be invalidated + * as soon as bdi_work_clear() has done the wakeup. */ - if (flags & (I_DIRTY_SYNC | I_DIRTY_DATASYNC)) { - if (sb->s_op->dirty_inode) - sb->s_op->dirty_inode(inode); - } + if (!bdi_work_on_stack(work)) + bdi_work_clear(work); + if (sync_mode == WB_SYNC_NONE || bdi_work_on_stack(work)) + call_rcu(&work->rcu_head, bdi_work_free); +} +static void wb_clear_pending(struct bdi_writeback *wb, struct bdi_work *work) +{ /* - * make sure that changes are seen by all cpus before we test i_state - * -- mikulas + * The caller has retrieved the work arguments from this work, + * drop our reference. If this is the last ref, delete and free it */ - smp_mb(); + if (atomic_dec_and_test(&work->pending)) { + struct backing_dev_info *bdi = wb->bdi; - /* avoid the locking if we can */ - if ((inode->i_state & flags) == flags) - return; - - if (unlikely(block_dump)) - block_dump___mark_inode_dirty(inode); + spin_lock(&bdi->wb_lock); + list_del_rcu(&work->list); + spin_unlock(&bdi->wb_lock); - spin_lock(&inode_lock); - if ((inode->i_state & flags) != flags) { - const int was_dirty = inode->i_state & I_DIRTY; + wb_work_complete(work); + } +} - inode->i_state |= flags; +static void bdi_queue_work(struct backing_dev_info *bdi, struct bdi_work *work) +{ + if (work) { + work->seen = bdi->wb_mask; + BUG_ON(!work->seen); + atomic_set(&work->pending, bdi->wb_cnt); + BUG_ON(!bdi->wb_cnt); /* - * If the inode is being synced, just update its dirty state. - * The unlocker will place the inode on the appropriate - * superblock list, based upon its state. + * Make sure stores are seen before it appears on the list */ - if (inode->i_state & I_SYNC) - goto out; + smp_mb(); - /* - * Only add valid (hashed) inodes to the superblock's - * dirty list. Add blockdev inodes as well. - */ - if (!S_ISBLK(inode->i_mode)) { - if (hlist_unhashed(&inode->i_hash)) - goto out; - } - if (inode->i_state & (I_FREEING|I_CLEAR)) - goto out; + spin_lock(&bdi->wb_lock); + list_add_tail_rcu(&work->list, &bdi->work_list); + spin_unlock(&bdi->wb_lock); + } + + /* + * If the default thread isn't there, make sure we add it. When + * it gets created and wakes up, we'll run this work. + */ + if (unlikely(list_empty_careful(&bdi->wb_list))) + wake_up_process(default_backing_dev_info.wb.task); + else { + struct bdi_writeback *wb = &bdi->wb; /* - * If the inode was already on b_dirty/b_io/b_more_io, don't - * reposition it (that would break b_dirty time-ordering). + * If we failed allocating the bdi work item, wake up the wb + * thread always. As a safety precaution, it'll flush out + * everything */ - if (!was_dirty) { - inode->dirtied_when = jiffies; - list_move(&inode->i_list, - &inode_to_bdi(inode)->b_dirty); - } + if (!wb_has_dirty_io(wb)) { + if (work) + wb_clear_pending(wb, work); + } else if (wb->task) + wake_up_process(wb->task); } -out: - spin_unlock(&inode_lock); } -EXPORT_SYMBOL(__mark_inode_dirty); +/* + * Used for on-stack allocated work items. The caller needs to wait until + * the wb threads have acked the work before it's safe to continue. + */ +static void bdi_wait_on_work_clear(struct bdi_work *work) +{ + wait_on_bit(&work->state, WS_USED_B, bdi_sched_wait, + TASK_UNINTERRUPTIBLE); +} -static int write_inode(struct inode *inode, int sync) +static struct bdi_work *bdi_alloc_work(struct writeback_control *wbc) { - if (inode->i_sb->s_op->write_inode && !is_bad_inode(inode)) - return inode->i_sb->s_op->write_inode(inode, sync); - return 0; + struct bdi_work *work; + + work = kmalloc(sizeof(*work), GFP_ATOMIC); + if (work) + bdi_work_init(work, wbc); + + return work; +} + +void bdi_start_writeback(struct writeback_control *wbc) +{ + const bool must_wait = wbc->sync_mode == WB_SYNC_ALL; + struct bdi_work work_stack, *work = NULL; + + if (!must_wait) + work = bdi_alloc_work(wbc); + + if (!work) { + work = &work_stack; + bdi_work_init_on_stack(work, wbc); + } + + bdi_queue_work(wbc->bdi, work); + + /* + * If the sync mode is WB_SYNC_ALL, block waiting for the work to + * complete. If not, we only need to wait for the work to be started, + * if we allocated it on-stack. We use the same mechanism, if the + * wait bit is set in the bdi_work struct, then threads will not + * clear pending until after they are done. + * + * Note that work == &work_stack if must_wait is true, so we don't + * need to do call_rcu() here ever, since the completion path will + * have done that for us. + */ + if (must_wait || work == &work_stack) { + bdi_wait_on_work_clear(work); + if (work != &work_stack) + call_rcu(&work->rcu_head, bdi_work_free); + } } /* @@ -199,16 +244,16 @@ static int write_inode(struct inode *inode, int sync) */ static void redirty_tail(struct inode *inode) { - struct backing_dev_info *bdi = inode_to_bdi(inode); + struct bdi_writeback *wb = &inode_to_bdi(inode)->wb; - if (!list_empty(&bdi->b_dirty)) { + if (!list_empty(&wb->b_dirty)) { struct inode *tail; - tail = list_entry(bdi->b_dirty.next, struct inode, i_list); + tail = list_entry(wb->b_dirty.next, struct inode, i_list); if (time_before(inode->dirtied_when, tail->dirtied_when)) inode->dirtied_when = jiffies; } - list_move(&inode->i_list, &bdi->b_dirty); + list_move(&inode->i_list, &wb->b_dirty); } /* @@ -216,7 +261,9 @@ static void redirty_tail(struct inode *inode) */ static void requeue_io(struct inode *inode) { - list_move(&inode->i_list, &inode_to_bdi(inode)->b_more_io); + struct bdi_writeback *wb = &inode_to_bdi(inode)->wb; + + list_move(&inode->i_list, &wb->b_more_io); } static void inode_sync_complete(struct inode *inode) @@ -263,52 +310,18 @@ static void move_expired_inodes(struct list_head *delaying_queue, /* * Queue all expired dirty inodes for io, eldest first. */ -static void queue_io(struct backing_dev_info *bdi, - unsigned long *older_than_this) +static void queue_io(struct bdi_writeback *wb, unsigned long *older_than_this) { - list_splice_init(&bdi->b_more_io, bdi->b_io.prev); - move_expired_inodes(&bdi->b_dirty, &bdi->b_io, older_than_this); + list_splice_init(&wb->b_more_io, wb->b_io.prev); + move_expired_inodes(&wb->b_dirty, &wb->b_io, older_than_this); } -static int sb_on_inode_list(struct super_block *sb, struct list_head *list) -{ - struct inode *inode; - int ret = 0; - - spin_lock(&inode_lock); - list_for_each_entry(inode, list, i_list) { - if (inode->i_sb == sb) { - ret = 1; - break; - } - } - spin_unlock(&inode_lock); - return ret; -} - -int sb_has_dirty_inodes(struct super_block *sb) +static int write_inode(struct inode *inode, int sync) { - struct backing_dev_info *bdi; - int ret = 0; - - /* - * This is REALLY expensive right now, but it'll go away - * when the bdi writeback is introduced - */ - mutex_lock(&bdi_lock); - list_for_each_entry(bdi, &bdi_list, bdi_list) { - if (sb_on_inode_list(sb, &bdi->b_dirty) || - sb_on_inode_list(sb, &bdi->b_io) || - sb_on_inode_list(sb, &bdi->b_more_io)) { - ret = 1; - break; - } - } - mutex_unlock(&bdi_lock); - - return ret; + if (inode->i_sb->s_op->write_inode && !is_bad_inode(inode)) + return inode->i_sb->s_op->write_inode(inode, sync); + return 0; } -EXPORT_SYMBOL(sb_has_dirty_inodes); /* * Wait for writeback on an inode to complete. @@ -466,20 +479,71 @@ writeback_single_inode(struct inode *inode, struct writeback_control *wbc) return ret; } -static void generic_sync_bdi_inodes(struct backing_dev_info *bdi, - struct writeback_control *wbc, - struct super_block *sb) +/* + * For WB_SYNC_NONE writeback, the caller does not have the sb pinned + * before calling writeback. So make sure that we do pin it, so it doesn't + * go away while we are writing inodes from it. + * + * Returns 0 if the super was successfully pinned (or pinning wasn't needed), + * 1 if we failed. + */ +static int pin_sb_for_writeback(struct writeback_control *wbc, + struct inode *inode) +{ + struct super_block *sb = inode->i_sb; + + /* + * Caller must already hold the ref for this + */ + if (wbc->sync_mode == WB_SYNC_ALL) { + WARN_ON(!rwsem_is_locked(&sb->s_umount)); + return 0; + } + + spin_lock(&sb_lock); + sb->s_count++; + if (down_read_trylock(&sb->s_umount)) { + if (sb->s_root) { + spin_unlock(&sb_lock); + return 0; + } + /* + * umounted, drop rwsem again and fall through to failure + */ + up_read(&sb->s_umount); + } + + sb->s_count--; + spin_unlock(&sb_lock); + return 1; +} + +static void unpin_sb_for_writeback(struct writeback_control *wbc, + struct inode *inode) +{ + struct super_block *sb = inode->i_sb; + + if (wbc->sync_mode == WB_SYNC_ALL) + return; + + up_read(&sb->s_umount); + put_super(sb); +} + +static void writeback_inodes_wb(struct bdi_writeback *wb, + struct writeback_control *wbc) { + struct super_block *sb = wbc->sb; const int is_blkdev_sb = sb_is_blkdev_sb(sb); const unsigned long start = jiffies; /* livelock avoidance */ spin_lock(&inode_lock); - if (!wbc->for_kupdate || list_empty(&bdi->b_io)) - queue_io(bdi, wbc->older_than_this); + if (!wbc->for_kupdate || list_empty(&wb->b_io)) + queue_io(wb, wbc->older_than_this); - while (!list_empty(&bdi->b_io)) { - struct inode *inode = list_entry(bdi->b_io.prev, + while (!list_empty(&wb->b_io)) { + struct inode *inode = list_entry(wb->b_io.prev, struct inode, i_list); long pages_skipped; @@ -491,7 +555,7 @@ static void generic_sync_bdi_inodes(struct backing_dev_info *bdi, continue; } - if (!bdi_cap_writeback_dirty(bdi)) { + if (!bdi_cap_writeback_dirty(wb->bdi)) { redirty_tail(inode); if (is_blkdev_sb) { /* @@ -513,7 +577,7 @@ static void generic_sync_bdi_inodes(struct backing_dev_info *bdi, continue; } - if (wbc->nonblocking && bdi_write_congested(bdi)) { + if (wbc->nonblocking && bdi_write_congested(wb->bdi)) { wbc->encountered_congestion = 1; if (!is_blkdev_sb) break; /* Skip a congested fs */ @@ -521,13 +585,6 @@ static void generic_sync_bdi_inodes(struct backing_dev_info *bdi, continue; /* Skip a congested blockdev */ } - if (wbc->bdi && bdi != wbc->bdi) { - if (!is_blkdev_sb) - break; /* fs has the wrong queue */ - requeue_io(inode); - continue; /* blockdev has wrong queue */ - } - /* * Was this inode dirtied after sync_sb_inodes was called? * This keeps sync from extra jobs and livelock. @@ -535,16 +592,16 @@ static void generic_sync_bdi_inodes(struct backing_dev_info *bdi, if (inode_dirtied_after(inode, start)) break; - /* Is another pdflush already flushing this queue? */ - if (current_is_pdflush() && !writeback_acquire(bdi)) - break; + if (pin_sb_for_writeback(wbc, inode)) { + requeue_io(inode); + continue; + } BUG_ON(inode->i_state & (I_FREEING | I_CLEAR)); __iget(inode); pages_skipped = wbc->pages_skipped; writeback_single_inode(inode, wbc); - if (current_is_pdflush()) - writeback_release(bdi); + unpin_sb_for_writeback(wbc, inode); if (wbc->pages_skipped != pages_skipped) { /* * writeback is not making progress due to locked @@ -560,7 +617,7 @@ static void generic_sync_bdi_inodes(struct backing_dev_info *bdi, wbc->more_io = 1; break; } - if (!list_empty(&bdi->b_more_io)) + if (!list_empty(&wb->b_more_io)) wbc->more_io = 1; } @@ -568,139 +625,500 @@ static void generic_sync_bdi_inodes(struct backing_dev_info *bdi, /* Leave any unwritten inodes on b_io */ } +void writeback_inodes_wbc(struct writeback_control *wbc) +{ + struct backing_dev_info *bdi = wbc->bdi; + + writeback_inodes_wb(&bdi->wb, wbc); +} + /* - * Write out a superblock's list of dirty inodes. A wait will be performed - * upon no inodes, all inodes or the final one, depending upon sync_mode. - * - * If older_than_this is non-NULL, then only write out inodes which - * had their first dirtying at a time earlier than *older_than_this. - * - * If we're a pdlfush thread, then implement pdflush collision avoidance - * against the entire list. + * The maximum number of pages to writeout in a single bdi flush/kupdate + * operation. We do this so we don't hold I_SYNC against an inode for + * enormous amounts of time, which would block a userspace task which has + * been forced to throttle against that inode. Also, the code reevaluates + * the dirty each time it has written this many pages. + */ +#define MAX_WRITEBACK_PAGES 1024 + +static inline bool over_bground_thresh(void) +{ + unsigned long background_thresh, dirty_thresh; + + get_dirty_limits(&background_thresh, &dirty_thresh, NULL, NULL); + + return (global_page_state(NR_FILE_DIRTY) + + global_page_state(NR_UNSTABLE_NFS) >= background_thresh); +} + +/* + * Explicit flushing or periodic writeback of "old" data. * - * If `bdi' is non-zero then we're being asked to writeback a specific queue. - * This function assumes that the blockdev superblock's inodes are backed by - * a variety of queues, so all inodes are searched. For other superblocks, - * assume that all inodes are backed by the same queue. + * Define "old": the first time one of an inode's pages is dirtied, we mark the + * dirtying-time in the inode's address_space. So this periodic writeback code + * just walks the superblock inode list, writing back any inodes which are + * older than a specific point in time. * - * FIXME: this linear search could get expensive with many fileystems. But - * how to fix? We need to go from an address_space to all inodes which share - * a queue with that address_space. (Easy: have a global "dirty superblocks" - * list). + * Try to run once per dirty_writeback_interval. But if a writeback event + * takes longer than a dirty_writeback_interval interval, then leave a + * one-second gap. * - * The inodes to be written are parked on bdi->b_io. They are moved back onto - * bdi->b_dirty as they are selected for writing. This way, none can be missed - * on the writer throttling path, and we get decent balancing between many - * throttled threads: we don't want them all piling up on inode_sync_wait. + * older_than_this takes precedence over nr_to_write. So we'll only write back + * all dirty pages if they are all attached to "old" mappings. */ -static void generic_sync_sb_inodes(struct super_block *sb, - struct writeback_control *wbc) +static long wb_writeback(struct bdi_writeback *wb, long nr_pages, + struct super_block *sb, + enum writeback_sync_modes sync_mode, int for_kupdate) { - struct backing_dev_info *bdi; - - if (!wbc->bdi) { - mutex_lock(&bdi_lock); - list_for_each_entry(bdi, &bdi_list, bdi_list) - generic_sync_bdi_inodes(bdi, wbc, sb); - mutex_unlock(&bdi_lock); - } else - generic_sync_bdi_inodes(wbc->bdi, wbc, sb); + struct writeback_control wbc = { + .bdi = wb->bdi, + .sb = sb, + .sync_mode = sync_mode, + .older_than_this = NULL, + .for_kupdate = for_kupdate, + .range_cyclic = 1, + }; + unsigned long oldest_jif; + long wrote = 0; - if (wbc->sync_mode == WB_SYNC_ALL) { - struct inode *inode, *old_inode = NULL; + if (wbc.for_kupdate) { + wbc.older_than_this = &oldest_jif; + oldest_jif = jiffies - + msecs_to_jiffies(dirty_expire_interval * 10); + } - spin_lock(&inode_lock); + for (;;) { + /* + * Don't flush anything for non-integrity writeback where + * no nr_pages was given + */ + if (!for_kupdate && nr_pages <= 0 && sync_mode == WB_SYNC_NONE) + break; /* - * Data integrity sync. Must wait for all pages under writeback, - * because there may have been pages dirtied before our sync - * call, but which had writeout started before we write it out. - * In which case, the inode may not be on the dirty list, but - * we still have to wait for that writeout. + * If no specific pages were given and this is just a + * periodic background writeout and we are below the + * background dirty threshold, don't do anything */ - list_for_each_entry(inode, &sb->s_inodes, i_sb_list) { - struct address_space *mapping; + if (for_kupdate && nr_pages <= 0 && !over_bground_thresh()) + break; - if (inode->i_state & - (I_FREEING|I_CLEAR|I_WILL_FREE|I_NEW)) - continue; - mapping = inode->i_mapping; - if (mapping->nrpages == 0) + wbc.more_io = 0; + wbc.encountered_congestion = 0; + wbc.nr_to_write = MAX_WRITEBACK_PAGES; + wbc.pages_skipped = 0; + writeback_inodes_wb(wb, &wbc); + nr_pages -= MAX_WRITEBACK_PAGES - wbc.nr_to_write; + wrote += MAX_WRITEBACK_PAGES - wbc.nr_to_write; + + /* + * If we ran out of stuff to write, bail unless more_io got set + */ + if (wbc.nr_to_write > 0 || wbc.pages_skipped > 0) { + if (wbc.more_io && !wbc.for_kupdate) continue; - __iget(inode); - spin_unlock(&inode_lock); + break; + } + } + + return wrote; +} + +/* + * Return the next bdi_work struct that hasn't been processed by this + * wb thread yet + */ +static struct bdi_work *get_next_work_item(struct backing_dev_info *bdi, + struct bdi_writeback *wb) +{ + struct bdi_work *work, *ret = NULL; + + rcu_read_lock(); + + list_for_each_entry_rcu(work, &bdi->work_list, list) { + if (!test_and_clear_bit(wb->nr, &work->seen)) + continue; + + ret = work; + break; + } + + rcu_read_unlock(); + return ret; +} + +static long wb_check_old_data_flush(struct bdi_writeback *wb) +{ + unsigned long expired; + long nr_pages; + + expired = wb->last_old_flush + + msecs_to_jiffies(dirty_writeback_interval * 10); + if (time_before(jiffies, expired)) + return 0; + + wb->last_old_flush = jiffies; + nr_pages = global_page_state(NR_FILE_DIRTY) + + global_page_state(NR_UNSTABLE_NFS) + + (inodes_stat.nr_inodes - inodes_stat.nr_unused); + + if (nr_pages) + return wb_writeback(wb, nr_pages, NULL, WB_SYNC_NONE, 1); + + return 0; +} + +/* + * Retrieve work items and do the writeback they describe + */ +long wb_do_writeback(struct bdi_writeback *wb, int force_wait) +{ + struct backing_dev_info *bdi = wb->bdi; + struct bdi_work *work; + long nr_pages, wrote = 0; + + while ((work = get_next_work_item(bdi, wb)) != NULL) { + enum writeback_sync_modes sync_mode; + + nr_pages = work->nr_pages; + + /* + * Override sync mode, in case we must wait for completion + */ + if (force_wait) + work->sync_mode = sync_mode = WB_SYNC_ALL; + else + sync_mode = work->sync_mode; + + /* + * If this isn't a data integrity operation, just notify + * that we have seen this work and we are now starting it. + */ + if (sync_mode == WB_SYNC_NONE) + wb_clear_pending(wb, work); + + wrote += wb_writeback(wb, nr_pages, work->sb, sync_mode, 0); + + /* + * This is a data integrity writeback, so only do the + * notification when we have completed the work. + */ + if (sync_mode == WB_SYNC_ALL) + wb_clear_pending(wb, work); + } + + /* + * Check for periodic writeback, kupdated() style + */ + wrote += wb_check_old_data_flush(wb); + + return wrote; +} + +/* + * Handle writeback of dirty data for the device backed by this bdi. Also + * wakes up periodically and does kupdated style flushing. + */ +int bdi_writeback_task(struct bdi_writeback *wb) +{ + unsigned long last_active = jiffies; + unsigned long wait_jiffies = -1UL; + long pages_written; + + while (!kthread_should_stop()) { + pages_written = wb_do_writeback(wb, 0); + + if (pages_written) + last_active = jiffies; + else if (wait_jiffies != -1UL) { + unsigned long max_idle; + /* - * We hold a reference to 'inode' so it couldn't have - * been removed from s_inodes list while we dropped the - * inode_lock. We cannot iput the inode now as we can - * be holding the last reference and we cannot iput it - * under inode_lock. So we keep the reference and iput - * it later. + * Longest period of inactivity that we tolerate. If we + * see dirty data again later, the task will get + * recreated automatically. */ - iput(old_inode); - old_inode = inode; + max_idle = max(5UL * 60 * HZ, wait_jiffies); + if (time_after(jiffies, max_idle + last_active)) + break; + } + + wait_jiffies = msecs_to_jiffies(dirty_writeback_interval * 10); + set_current_state(TASK_INTERRUPTIBLE); + schedule_timeout(wait_jiffies); + try_to_freeze(); + } + + return 0; +} + +/* + * Schedule writeback for all backing devices. Expensive! If this is a data + * integrity operation, writeback will be complete when this returns. If + * we are simply called for WB_SYNC_NONE, then writeback will merely be + * scheduled to run. + */ +static void bdi_writeback_all(struct writeback_control *wbc) +{ + const bool must_wait = wbc->sync_mode == WB_SYNC_ALL; + struct backing_dev_info *bdi; + struct bdi_work *work; + LIST_HEAD(list); + +restart: + spin_lock(&bdi_lock); + + list_for_each_entry(bdi, &bdi_list, bdi_list) { + struct bdi_work *work; + + if (!bdi_has_dirty_io(bdi)) + continue; - filemap_fdatawait(mapping); + /* + * If work allocation fails, do the writes inline. We drop + * the lock and restart the list writeout. This should be OK, + * since this happens rarely and because the writeout should + * eventually make more free memory available. + */ + work = bdi_alloc_work(wbc); + if (!work) { + struct writeback_control __wbc; - cond_resched(); + /* + * Not a data integrity writeout, just continue + */ + if (!must_wait) + continue; - spin_lock(&inode_lock); + spin_unlock(&bdi_lock); + __wbc = *wbc; + __wbc.bdi = bdi; + writeback_inodes_wbc(&__wbc); + goto restart; } - spin_unlock(&inode_lock); - iput(old_inode); + if (must_wait) + list_add_tail(&work->wait_list, &list); + + bdi_queue_work(bdi, work); + } + + spin_unlock(&bdi_lock); + + /* + * If this is for WB_SYNC_ALL, wait for pending work to complete + * before returning. + */ + while (!list_empty(&list)) { + work = list_entry(list.next, struct bdi_work, wait_list); + list_del(&work->wait_list); + bdi_wait_on_work_clear(work); + call_rcu(&work->rcu_head, bdi_work_free); } } /* - * Start writeback of dirty pagecache data against all unlocked inodes. + * Start writeback of `nr_pages' pages. If `nr_pages' is zero, write back + * the whole world. + */ +void wakeup_flusher_threads(long nr_pages) +{ + struct writeback_control wbc = { + .sync_mode = WB_SYNC_NONE, + .older_than_this = NULL, + .range_cyclic = 1, + }; + + if (nr_pages == 0) + nr_pages = global_page_state(NR_FILE_DIRTY) + + global_page_state(NR_UNSTABLE_NFS); + wbc.nr_to_write = nr_pages; + bdi_writeback_all(&wbc); +} + +static noinline void block_dump___mark_inode_dirty(struct inode *inode) +{ + if (inode->i_ino || strcmp(inode->i_sb->s_id, "bdev")) { + struct dentry *dentry; + const char *name = "?"; + + dentry = d_find_alias(inode); + if (dentry) { + spin_lock(&dentry->d_lock); + name = (const char *) dentry->d_name.name; + } + printk(KERN_DEBUG + "%s(%d): dirtied inode %lu (%s) on %s\n", + current->comm, task_pid_nr(current), inode->i_ino, + name, inode->i_sb->s_id); + if (dentry) { + spin_unlock(&dentry->d_lock); + dput(dentry); + } + } +} + +/** + * __mark_inode_dirty - internal function + * @inode: inode to mark + * @flags: what kind of dirty (i.e. I_DIRTY_SYNC) + * Mark an inode as dirty. Callers should use mark_inode_dirty or + * mark_inode_dirty_sync. * - * Note: - * We don't need to grab a reference to superblock here. If it has non-empty - * ->b_dirty it's hadn't been killed yet and kill_super() won't proceed - * past sync_inodes_sb() until the ->b_dirty/b_io/b_more_io lists are all - * empty. Since __sync_single_inode() regains inode_lock before it finally moves - * inode from superblock lists we are OK. + * Put the inode on the super block's dirty list. + * + * CAREFUL! We mark it dirty unconditionally, but move it onto the + * dirty list only if it is hashed or if it refers to a blockdev. + * If it was not hashed, it will never be added to the dirty list + * even if it is later hashed, as it will have been marked dirty already. + * + * In short, make sure you hash any inodes _before_ you start marking + * them dirty. * - * If `older_than_this' is non-zero then only flush inodes which have a - * flushtime older than *older_than_this. + * This function *must* be atomic for the I_DIRTY_PAGES case - + * set_page_dirty() is called under spinlock in several places. * - * If `bdi' is non-zero then we will scan the first inode against each - * superblock until we find the matching ones. One group will be the dirty - * inodes against a filesystem. Then when we hit the dummy blockdev superblock, - * sync_sb_inodes will seekout the blockdev which matches `bdi'. Maybe not - * super-efficient but we're about to do a ton of I/O... + * Note that for blockdevs, inode->dirtied_when represents the dirtying time of + * the block-special inode (/dev/hda1) itself. And the ->dirtied_when field of + * the kernel-internal blockdev inode represents the dirtying time of the + * blockdev's pages. This is why for I_DIRTY_PAGES we always use + * page->mapping->host, so the page-dirtying time is recorded in the internal + * blockdev inode. */ -void -writeback_inodes(struct writeback_control *wbc) +void __mark_inode_dirty(struct inode *inode, int flags) { - struct super_block *sb; + struct super_block *sb = inode->i_sb; - might_sleep(); - spin_lock(&sb_lock); -restart: - list_for_each_entry_reverse(sb, &super_blocks, s_list) { - if (sb_has_dirty_inodes(sb)) { - /* we're making our own get_super here */ - sb->s_count++; - spin_unlock(&sb_lock); - /* - * If we can't get the readlock, there's no sense in - * waiting around, most of the time the FS is going to - * be unmounted by the time it is released. - */ - if (down_read_trylock(&sb->s_umount)) { - if (sb->s_root) - generic_sync_sb_inodes(sb, wbc); - up_read(&sb->s_umount); - } - spin_lock(&sb_lock); - if (__put_super_and_need_restart(sb)) - goto restart; + /* + * Don't do this for I_DIRTY_PAGES - that doesn't actually + * dirty the inode itself + */ + if (flags & (I_DIRTY_SYNC | I_DIRTY_DATASYNC)) { + if (sb->s_op->dirty_inode) + sb->s_op->dirty_inode(inode); + } + + /* + * make sure that changes are seen by all cpus before we test i_state + * -- mikulas + */ + smp_mb(); + + /* avoid the locking if we can */ + if ((inode->i_state & flags) == flags) + return; + + if (unlikely(block_dump)) + block_dump___mark_inode_dirty(inode); + + spin_lock(&inode_lock); + if ((inode->i_state & flags) != flags) { + const int was_dirty = inode->i_state & I_DIRTY; + + inode->i_state |= flags; + + /* + * If the inode is being synced, just update its dirty state. + * The unlocker will place the inode on the appropriate + * superblock list, based upon its state. + */ + if (inode->i_state & I_SYNC) + goto out; + + /* + * Only add valid (hashed) inodes to the superblock's + * dirty list. Add blockdev inodes as well. + */ + if (!S_ISBLK(inode->i_mode)) { + if (hlist_unhashed(&inode->i_hash)) + goto out; + } + if (inode->i_state & (I_FREEING|I_CLEAR)) + goto out; + + /* + * If the inode was already on b_dirty/b_io/b_more_io, don't + * reposition it (that would break b_dirty time-ordering). + */ + if (!was_dirty) { + struct bdi_writeback *wb = &inode_to_bdi(inode)->wb; + + inode->dirtied_when = jiffies; + list_move(&inode->i_list, &wb->b_dirty); } - if (wbc->nr_to_write <= 0) - break; } - spin_unlock(&sb_lock); +out: + spin_unlock(&inode_lock); +} +EXPORT_SYMBOL(__mark_inode_dirty); + +/* + * Write out a superblock's list of dirty inodes. A wait will be performed + * upon no inodes, all inodes or the final one, depending upon sync_mode. + * + * If older_than_this is non-NULL, then only write out inodes which + * had their first dirtying at a time earlier than *older_than_this. + * + * If we're a pdlfush thread, then implement pdflush collision avoidance + * against the entire list. + * + * If `bdi' is non-zero then we're being asked to writeback a specific queue. + * This function assumes that the blockdev superblock's inodes are backed by + * a variety of queues, so all inodes are searched. For other superblocks, + * assume that all inodes are backed by the same queue. + * + * The inodes to be written are parked on bdi->b_io. They are moved back onto + * bdi->b_dirty as they are selected for writing. This way, none can be missed + * on the writer throttling path, and we get decent balancing between many + * throttled threads: we don't want them all piling up on inode_sync_wait. + */ +static void wait_sb_inodes(struct writeback_control *wbc) +{ + struct inode *inode, *old_inode = NULL; + + /* + * We need to be protected against the filesystem going from + * r/o to r/w or vice versa. + */ + WARN_ON(!rwsem_is_locked(&wbc->sb->s_umount)); + + spin_lock(&inode_lock); + + /* + * Data integrity sync. Must wait for all pages under writeback, + * because there may have been pages dirtied before our sync + * call, but which had writeout started before we write it out. + * In which case, the inode may not be on the dirty list, but + * we still have to wait for that writeout. + */ + list_for_each_entry(inode, &wbc->sb->s_inodes, i_sb_list) { + struct address_space *mapping; + + if (inode->i_state & (I_FREEING|I_CLEAR|I_WILL_FREE|I_NEW)) + continue; + mapping = inode->i_mapping; + if (mapping->nrpages == 0) + continue; + __iget(inode); + spin_unlock(&inode_lock); + /* + * We hold a reference to 'inode' so it couldn't have + * been removed from s_inodes list while we dropped the + * inode_lock. We cannot iput the inode now as we can + * be holding the last reference and we cannot iput it + * under inode_lock. So we keep the reference and iput + * it later. + */ + iput(old_inode); + old_inode = inode; + + filemap_fdatawait(mapping); + + cond_resched(); + + spin_lock(&inode_lock); + } + spin_unlock(&inode_lock); + iput(old_inode); } /** @@ -715,6 +1133,7 @@ restart: long writeback_inodes_sb(struct super_block *sb) { struct writeback_control wbc = { + .sb = sb, .sync_mode = WB_SYNC_NONE, .range_start = 0, .range_end = LLONG_MAX, @@ -727,7 +1146,7 @@ long writeback_inodes_sb(struct super_block *sb) (inodes_stat.nr_inodes - inodes_stat.nr_unused); wbc.nr_to_write = nr_to_write; - generic_sync_sb_inodes(sb, &wbc); + bdi_writeback_all(&wbc); return nr_to_write - wbc.nr_to_write; } EXPORT_SYMBOL(writeback_inodes_sb); @@ -742,6 +1161,7 @@ EXPORT_SYMBOL(writeback_inodes_sb); long sync_inodes_sb(struct super_block *sb) { struct writeback_control wbc = { + .sb = sb, .sync_mode = WB_SYNC_ALL, .range_start = 0, .range_end = LLONG_MAX, @@ -749,7 +1169,8 @@ long sync_inodes_sb(struct super_block *sb) long nr_to_write = LONG_MAX; /* doesn't actually matter */ wbc.nr_to_write = nr_to_write; - generic_sync_sb_inodes(sb, &wbc); + bdi_writeback_all(&wbc); + wait_sb_inodes(&wbc); return nr_to_write - wbc.nr_to_write; } EXPORT_SYMBOL(sync_inodes_sb); diff --git a/fs/super.c b/fs/super.c index 0d22ce3be4aa..9cda337ddae2 100644 --- a/fs/super.c +++ b/fs/super.c @@ -168,7 +168,7 @@ int __put_super_and_need_restart(struct super_block *sb) * Drops a temporary reference, frees superblock if there's no * references left. */ -static void put_super(struct super_block *sb) +void put_super(struct super_block *sb) { spin_lock(&sb_lock); __put_super(sb); diff --git a/fs/sync.c b/fs/sync.c index 66f210476f40..103cc7fdd3df 100644 --- a/fs/sync.c +++ b/fs/sync.c @@ -120,7 +120,7 @@ restart: */ SYSCALL_DEFINE0(sync) { - wakeup_pdflush(0); + wakeup_flusher_threads(0); sync_filesystems(0); sync_filesystems(1); if (unlikely(laptop_mode)) diff --git a/include/linux/backing-dev.h b/include/linux/backing-dev.h index 928cd5484f4d..d045f5f615c7 100644 --- a/include/linux/backing-dev.h +++ b/include/linux/backing-dev.h @@ -13,6 +13,8 @@ #include #include #include +#include +#include #include struct page; @@ -23,7 +25,8 @@ struct dentry; * Bits in backing_dev_info.state */ enum bdi_state { - BDI_pdflush, /* A pdflush thread is working this device */ + BDI_pending, /* On its way to being activated */ + BDI_wb_alloc, /* Default embedded wb allocated */ BDI_async_congested, /* The async (write) queue is getting full */ BDI_sync_congested, /* The sync queue is getting full */ BDI_unused, /* Available bits start here */ @@ -39,9 +42,22 @@ enum bdi_stat_item { #define BDI_STAT_BATCH (8*(1+ilog2(nr_cpu_ids))) +struct bdi_writeback { + struct list_head list; /* hangs off the bdi */ + + struct backing_dev_info *bdi; /* our parent bdi */ + unsigned int nr; + + unsigned long last_old_flush; /* last old data flush */ + + struct task_struct *task; /* writeback task */ + struct list_head b_dirty; /* dirty inodes */ + struct list_head b_io; /* parked for writeback */ + struct list_head b_more_io; /* parked for more writeback */ +}; + struct backing_dev_info { struct list_head bdi_list; - unsigned long ra_pages; /* max readahead in PAGE_CACHE_SIZE units */ unsigned long state; /* Always use atomic bitops on this */ unsigned int capabilities; /* Device capabilities */ @@ -58,11 +74,15 @@ struct backing_dev_info { unsigned int min_ratio; unsigned int max_ratio, max_prop_frac; - struct device *dev; + struct bdi_writeback wb; /* default writeback info for this bdi */ + spinlock_t wb_lock; /* protects update side of wb_list */ + struct list_head wb_list; /* the flusher threads hanging off this bdi */ + unsigned long wb_mask; /* bitmask of registered tasks */ + unsigned int wb_cnt; /* number of registered tasks */ - struct list_head b_dirty; /* dirty inodes */ - struct list_head b_io; /* parked for writeback */ - struct list_head b_more_io; /* parked for more writeback */ + struct list_head work_list; + + struct device *dev; #ifdef CONFIG_DEBUG_FS struct dentry *debug_dir; @@ -77,10 +97,20 @@ int bdi_register(struct backing_dev_info *bdi, struct device *parent, const char *fmt, ...); int bdi_register_dev(struct backing_dev_info *bdi, dev_t dev); void bdi_unregister(struct backing_dev_info *bdi); +void bdi_start_writeback(struct writeback_control *wbc); +int bdi_writeback_task(struct bdi_writeback *wb); +int bdi_has_dirty_io(struct backing_dev_info *bdi); -extern struct mutex bdi_lock; +extern spinlock_t bdi_lock; extern struct list_head bdi_list; +static inline int wb_has_dirty_io(struct bdi_writeback *wb) +{ + return !list_empty(&wb->b_dirty) || + !list_empty(&wb->b_io) || + !list_empty(&wb->b_more_io); +} + static inline void __add_bdi_stat(struct backing_dev_info *bdi, enum bdi_stat_item item, s64 amount) { @@ -270,6 +300,11 @@ static inline bool bdi_cap_swap_backed(struct backing_dev_info *bdi) return bdi->capabilities & BDI_CAP_SWAP_BACKED; } +static inline bool bdi_cap_flush_forker(struct backing_dev_info *bdi) +{ + return bdi == &default_backing_dev_info; +} + static inline bool mapping_cap_writeback_dirty(struct address_space *mapping) { return bdi_cap_writeback_dirty(mapping->backing_dev_info); @@ -285,4 +320,10 @@ static inline bool mapping_cap_swap_backed(struct address_space *mapping) return bdi_cap_swap_backed(mapping->backing_dev_info); } +static inline int bdi_sched_wait(void *word) +{ + schedule(); + return 0; +} + #endif /* _LINUX_BACKING_DEV_H */ diff --git a/include/linux/fs.h b/include/linux/fs.h index 56371be1be65..26da98f61116 100644 --- a/include/linux/fs.h +++ b/include/linux/fs.h @@ -1786,6 +1786,7 @@ extern int get_sb_pseudo(struct file_system_type *, char *, struct vfsmount *mnt); extern void simple_set_mnt(struct vfsmount *mnt, struct super_block *sb); int __put_super_and_need_restart(struct super_block *sb); +void put_super(struct super_block *sb); /* Alas, no aliases. Too much hassle with bringing module.h everywhere */ #define fops_get(fops) \ @@ -2182,7 +2183,6 @@ extern int bdev_read_only(struct block_device *); extern int set_blocksize(struct block_device *, int); extern int sb_set_blocksize(struct super_block *, int); extern int sb_min_blocksize(struct super_block *, int); -extern int sb_has_dirty_inodes(struct super_block *); extern int generic_file_mmap(struct file *, struct vm_area_struct *); extern int generic_file_readonly_mmap(struct file *, struct vm_area_struct *); diff --git a/include/linux/writeback.h b/include/linux/writeback.h index 07039299603d..cef75527a14c 100644 --- a/include/linux/writeback.h +++ b/include/linux/writeback.h @@ -40,6 +40,8 @@ enum writeback_sync_modes { struct writeback_control { struct backing_dev_info *bdi; /* If !NULL, only write back this queue */ + struct super_block *sb; /* if !NULL, only write inodes from + this super_block */ enum writeback_sync_modes sync_mode; unsigned long *older_than_this; /* If !NULL, only write back inodes older than this */ @@ -76,10 +78,13 @@ struct writeback_control { /* * fs/fs-writeback.c */ -void writeback_inodes(struct writeback_control *wbc); +struct bdi_writeback; int inode_wait(void *); long writeback_inodes_sb(struct super_block *); long sync_inodes_sb(struct super_block *); +void writeback_inodes_wbc(struct writeback_control *wbc); +long wb_do_writeback(struct bdi_writeback *wb, int force_wait); +void wakeup_flusher_threads(long nr_pages); /* writeback.h requires fs.h; it, too, is not included from here. */ static inline void wait_on_inode(struct inode *inode) @@ -99,7 +104,6 @@ static inline void inode_sync_wait(struct inode *inode) /* * mm/page-writeback.c */ -int wakeup_pdflush(long nr_pages); void laptop_io_completion(void); void laptop_sync_completion(void); void throttle_vm_writeout(gfp_t gfp_mask); diff --git a/mm/backing-dev.c b/mm/backing-dev.c index 6f163e0f0509..7f3fa79f25c0 100644 --- a/mm/backing-dev.c +++ b/mm/backing-dev.c @@ -1,8 +1,11 @@ #include #include +#include +#include #include #include +#include #include #include #include @@ -22,8 +25,18 @@ struct backing_dev_info default_backing_dev_info = { EXPORT_SYMBOL_GPL(default_backing_dev_info); static struct class *bdi_class; -DEFINE_MUTEX(bdi_lock); +DEFINE_SPINLOCK(bdi_lock); LIST_HEAD(bdi_list); +LIST_HEAD(bdi_pending_list); + +static struct task_struct *sync_supers_tsk; +static struct timer_list sync_supers_timer; + +static int bdi_sync_supers(void *); +static void sync_supers_timer_fn(unsigned long); +static void arm_supers_timer(void); + +static void bdi_add_default_flusher_task(struct backing_dev_info *bdi); #ifdef CONFIG_DEBUG_FS #include @@ -187,6 +200,13 @@ static int __init default_bdi_init(void) { int err; + sync_supers_tsk = kthread_run(bdi_sync_supers, NULL, "sync_supers"); + BUG_ON(IS_ERR(sync_supers_tsk)); + + init_timer(&sync_supers_timer); + setup_timer(&sync_supers_timer, sync_supers_timer_fn, 0); + arm_supers_timer(); + err = bdi_init(&default_backing_dev_info); if (!err) bdi_register(&default_backing_dev_info, NULL, "default"); @@ -195,6 +215,242 @@ static int __init default_bdi_init(void) } subsys_initcall(default_bdi_init); +static void bdi_wb_init(struct bdi_writeback *wb, struct backing_dev_info *bdi) +{ + memset(wb, 0, sizeof(*wb)); + + wb->bdi = bdi; + wb->last_old_flush = jiffies; + INIT_LIST_HEAD(&wb->b_dirty); + INIT_LIST_HEAD(&wb->b_io); + INIT_LIST_HEAD(&wb->b_more_io); +} + +static void bdi_task_init(struct backing_dev_info *bdi, + struct bdi_writeback *wb) +{ + struct task_struct *tsk = current; + + spin_lock(&bdi->wb_lock); + list_add_tail_rcu(&wb->list, &bdi->wb_list); + spin_unlock(&bdi->wb_lock); + + tsk->flags |= PF_FLUSHER | PF_SWAPWRITE; + set_freezable(); + + /* + * Our parent may run at a different priority, just set us to normal + */ + set_user_nice(tsk, 0); +} + +static int bdi_start_fn(void *ptr) +{ + struct bdi_writeback *wb = ptr; + struct backing_dev_info *bdi = wb->bdi; + int ret; + + /* + * Add us to the active bdi_list + */ + spin_lock(&bdi_lock); + list_add(&bdi->bdi_list, &bdi_list); + spin_unlock(&bdi_lock); + + bdi_task_init(bdi, wb); + + /* + * Clear pending bit and wakeup anybody waiting to tear us down + */ + clear_bit(BDI_pending, &bdi->state); + smp_mb__after_clear_bit(); + wake_up_bit(&bdi->state, BDI_pending); + + ret = bdi_writeback_task(wb); + + /* + * Remove us from the list + */ + spin_lock(&bdi->wb_lock); + list_del_rcu(&wb->list); + spin_unlock(&bdi->wb_lock); + + /* + * Flush any work that raced with us exiting. No new work + * will be added, since this bdi isn't discoverable anymore. + */ + if (!list_empty(&bdi->work_list)) + wb_do_writeback(wb, 1); + + wb->task = NULL; + return ret; +} + +int bdi_has_dirty_io(struct backing_dev_info *bdi) +{ + return wb_has_dirty_io(&bdi->wb); +} + +static void bdi_flush_io(struct backing_dev_info *bdi) +{ + struct writeback_control wbc = { + .bdi = bdi, + .sync_mode = WB_SYNC_NONE, + .older_than_this = NULL, + .range_cyclic = 1, + .nr_to_write = 1024, + }; + + writeback_inodes_wbc(&wbc); +} + +/* + * kupdated() used to do this. We cannot do it from the bdi_forker_task() + * or we risk deadlocking on ->s_umount. The longer term solution would be + * to implement sync_supers_bdi() or similar and simply do it from the + * bdi writeback tasks individually. + */ +static int bdi_sync_supers(void *unused) +{ + set_user_nice(current, 0); + + while (!kthread_should_stop()) { + set_current_state(TASK_INTERRUPTIBLE); + schedule(); + + /* + * Do this periodically, like kupdated() did before. + */ + sync_supers(); + } + + return 0; +} + +static void arm_supers_timer(void) +{ + unsigned long next; + + next = msecs_to_jiffies(dirty_writeback_interval * 10) + jiffies; + mod_timer(&sync_supers_timer, round_jiffies_up(next)); +} + +static void sync_supers_timer_fn(unsigned long unused) +{ + wake_up_process(sync_supers_tsk); + arm_supers_timer(); +} + +static int bdi_forker_task(void *ptr) +{ + struct bdi_writeback *me = ptr; + + bdi_task_init(me->bdi, me); + + for (;;) { + struct backing_dev_info *bdi, *tmp; + struct bdi_writeback *wb; + + /* + * Temporary measure, we want to make sure we don't see + * dirty data on the default backing_dev_info + */ + if (wb_has_dirty_io(me) || !list_empty(&me->bdi->work_list)) + wb_do_writeback(me, 0); + + spin_lock(&bdi_lock); + + /* + * Check if any existing bdi's have dirty data without + * a thread registered. If so, set that up. + */ + list_for_each_entry_safe(bdi, tmp, &bdi_list, bdi_list) { + if (bdi->wb.task) + continue; + if (list_empty(&bdi->work_list) && + !bdi_has_dirty_io(bdi)) + continue; + + bdi_add_default_flusher_task(bdi); + } + + set_current_state(TASK_INTERRUPTIBLE); + + if (list_empty(&bdi_pending_list)) { + unsigned long wait; + + spin_unlock(&bdi_lock); + wait = msecs_to_jiffies(dirty_writeback_interval * 10); + schedule_timeout(wait); + try_to_freeze(); + continue; + } + + __set_current_state(TASK_RUNNING); + + /* + * This is our real job - check for pending entries in + * bdi_pending_list, and create the tasks that got added + */ + bdi = list_entry(bdi_pending_list.next, struct backing_dev_info, + bdi_list); + list_del_init(&bdi->bdi_list); + spin_unlock(&bdi_lock); + + wb = &bdi->wb; + wb->task = kthread_run(bdi_start_fn, wb, "flush-%s", + dev_name(bdi->dev)); + /* + * If task creation fails, then readd the bdi to + * the pending list and force writeout of the bdi + * from this forker thread. That will free some memory + * and we can try again. + */ + if (IS_ERR(wb->task)) { + wb->task = NULL; + + /* + * Add this 'bdi' to the back, so we get + * a chance to flush other bdi's to free + * memory. + */ + spin_lock(&bdi_lock); + list_add_tail(&bdi->bdi_list, &bdi_pending_list); + spin_unlock(&bdi_lock); + + bdi_flush_io(bdi); + } + } + + return 0; +} + +/* + * Add the default flusher task that gets created for any bdi + * that has dirty data pending writeout + */ +void static bdi_add_default_flusher_task(struct backing_dev_info *bdi) +{ + if (!bdi_cap_writeback_dirty(bdi)) + return; + + /* + * Check with the helper whether to proceed adding a task. Will only + * abort if we two or more simultanous calls to + * bdi_add_default_flusher_task() occured, further additions will block + * waiting for previous additions to finish. + */ + if (!test_and_set_bit(BDI_pending, &bdi->state)) { + list_move_tail(&bdi->bdi_list, &bdi_pending_list); + + /* + * We are now on the pending list, wake up bdi_forker_task() + * to finish the job and add us back to the active bdi_list + */ + wake_up_process(default_backing_dev_info.wb.task); + } +} + int bdi_register(struct backing_dev_info *bdi, struct device *parent, const char *fmt, ...) { @@ -213,13 +469,34 @@ int bdi_register(struct backing_dev_info *bdi, struct device *parent, goto exit; } - mutex_lock(&bdi_lock); + spin_lock(&bdi_lock); list_add_tail(&bdi->bdi_list, &bdi_list); - mutex_unlock(&bdi_lock); + spin_unlock(&bdi_lock); bdi->dev = dev; - bdi_debug_register(bdi, dev_name(dev)); + /* + * Just start the forker thread for our default backing_dev_info, + * and add other bdi's to the list. They will get a thread created + * on-demand when they need it. + */ + if (bdi_cap_flush_forker(bdi)) { + struct bdi_writeback *wb = &bdi->wb; + + wb->task = kthread_run(bdi_forker_task, wb, "bdi-%s", + dev_name(dev)); + if (IS_ERR(wb->task)) { + wb->task = NULL; + ret = -ENOMEM; + + spin_lock(&bdi_lock); + list_del(&bdi->bdi_list); + spin_unlock(&bdi_lock); + goto exit; + } + } + + bdi_debug_register(bdi, dev_name(dev)); exit: return ret; } @@ -231,17 +508,42 @@ int bdi_register_dev(struct backing_dev_info *bdi, dev_t dev) } EXPORT_SYMBOL(bdi_register_dev); -static void bdi_remove_from_list(struct backing_dev_info *bdi) +/* + * Remove bdi from the global list and shutdown any threads we have running + */ +static void bdi_wb_shutdown(struct backing_dev_info *bdi) { - mutex_lock(&bdi_lock); + struct bdi_writeback *wb; + + if (!bdi_cap_writeback_dirty(bdi)) + return; + + /* + * If setup is pending, wait for that to complete first + */ + wait_on_bit(&bdi->state, BDI_pending, bdi_sched_wait, + TASK_UNINTERRUPTIBLE); + + /* + * Make sure nobody finds us on the bdi_list anymore + */ + spin_lock(&bdi_lock); list_del(&bdi->bdi_list); - mutex_unlock(&bdi_lock); + spin_unlock(&bdi_lock); + + /* + * Finally, kill the kernel threads. We don't need to be RCU + * safe anymore, since the bdi is gone from visibility. + */ + list_for_each_entry(wb, &bdi->wb_list, list) + kthread_stop(wb->task); } void bdi_unregister(struct backing_dev_info *bdi) { if (bdi->dev) { - bdi_remove_from_list(bdi); + if (!bdi_cap_flush_forker(bdi)) + bdi_wb_shutdown(bdi); bdi_debug_unregister(bdi); device_unregister(bdi->dev); bdi->dev = NULL; @@ -251,18 +553,25 @@ EXPORT_SYMBOL(bdi_unregister); int bdi_init(struct backing_dev_info *bdi) { - int i; - int err; + int i, err; bdi->dev = NULL; bdi->min_ratio = 0; bdi->max_ratio = 100; bdi->max_prop_frac = PROP_FRAC_BASE; + spin_lock_init(&bdi->wb_lock); INIT_LIST_HEAD(&bdi->bdi_list); - INIT_LIST_HEAD(&bdi->b_io); - INIT_LIST_HEAD(&bdi->b_dirty); - INIT_LIST_HEAD(&bdi->b_more_io); + INIT_LIST_HEAD(&bdi->wb_list); + INIT_LIST_HEAD(&bdi->work_list); + + bdi_wb_init(&bdi->wb, bdi); + + /* + * Just one thread support for now, hard code mask and count + */ + bdi->wb_mask = 1; + bdi->wb_cnt = 1; for (i = 0; i < NR_BDI_STAT_ITEMS; i++) { err = percpu_counter_init(&bdi->bdi_stat[i], 0); @@ -277,8 +586,6 @@ int bdi_init(struct backing_dev_info *bdi) err: while (i--) percpu_counter_destroy(&bdi->bdi_stat[i]); - - bdi_remove_from_list(bdi); } return err; @@ -289,9 +596,7 @@ void bdi_destroy(struct backing_dev_info *bdi) { int i; - WARN_ON(!list_empty(&bdi->b_dirty)); - WARN_ON(!list_empty(&bdi->b_io)); - WARN_ON(!list_empty(&bdi->b_more_io)); + WARN_ON(bdi_has_dirty_io(bdi)); bdi_unregister(bdi); diff --git a/mm/page-writeback.c b/mm/page-writeback.c index f8341b6019bf..25e7770309b8 100644 --- a/mm/page-writeback.c +++ b/mm/page-writeback.c @@ -35,15 +35,6 @@ #include #include -/* - * The maximum number of pages to writeout in a single bdflush/kupdate - * operation. We do this so we don't hold I_SYNC against an inode for - * enormous amounts of time, which would block a userspace task which has - * been forced to throttle against that inode. Also, the code reevaluates - * the dirty each time it has written this many pages. - */ -#define MAX_WRITEBACK_PAGES 1024 - /* * After a CPU has dirtied this many pages, balance_dirty_pages_ratelimited * will look to see if it needs to force writeback or throttling. @@ -117,8 +108,6 @@ EXPORT_SYMBOL(laptop_mode); /* End of sysctl-exported parameters */ -static void background_writeout(unsigned long _min_pages); - /* * Scale the writeback cache size proportional to the relative writeout speeds. * @@ -326,7 +315,7 @@ int bdi_set_min_ratio(struct backing_dev_info *bdi, unsigned int min_ratio) { int ret = 0; - mutex_lock(&bdi_lock); + spin_lock(&bdi_lock); if (min_ratio > bdi->max_ratio) { ret = -EINVAL; } else { @@ -338,7 +327,7 @@ int bdi_set_min_ratio(struct backing_dev_info *bdi, unsigned int min_ratio) ret = -EINVAL; } } - mutex_unlock(&bdi_lock); + spin_unlock(&bdi_lock); return ret; } @@ -350,14 +339,14 @@ int bdi_set_max_ratio(struct backing_dev_info *bdi, unsigned max_ratio) if (max_ratio > 100) return -EINVAL; - mutex_lock(&bdi_lock); + spin_lock(&bdi_lock); if (bdi->min_ratio > max_ratio) { ret = -EINVAL; } else { bdi->max_ratio = max_ratio; bdi->max_prop_frac = (PROP_FRAC_BASE * max_ratio) / 100; } - mutex_unlock(&bdi_lock); + spin_unlock(&bdi_lock); return ret; } @@ -543,7 +532,7 @@ static void balance_dirty_pages(struct address_space *mapping) * up. */ if (bdi_nr_reclaimable > bdi_thresh) { - writeback_inodes(&wbc); + writeback_inodes_wbc(&wbc); pages_written += write_chunk - wbc.nr_to_write; get_dirty_limits(&background_thresh, &dirty_thresh, &bdi_thresh, bdi); @@ -572,7 +561,7 @@ static void balance_dirty_pages(struct address_space *mapping) if (pages_written >= write_chunk) break; /* We've done our duty */ - congestion_wait(BLK_RW_ASYNC, HZ/10); + schedule_timeout(1); } if (bdi_nr_reclaimable + bdi_nr_writeback < bdi_thresh && @@ -591,10 +580,18 @@ static void balance_dirty_pages(struct address_space *mapping) * background_thresh, to keep the amount of dirty memory low. */ if ((laptop_mode && pages_written) || - (!laptop_mode && (global_page_state(NR_FILE_DIRTY) - + global_page_state(NR_UNSTABLE_NFS) - > background_thresh))) - pdflush_operation(background_writeout, 0); + (!laptop_mode && ((nr_writeback = global_page_state(NR_FILE_DIRTY) + + global_page_state(NR_UNSTABLE_NFS)) + > background_thresh))) { + struct writeback_control wbc = { + .bdi = bdi, + .sync_mode = WB_SYNC_NONE, + .nr_to_write = nr_writeback, + }; + + + bdi_start_writeback(&wbc); + } } void set_page_dirty_balance(struct page *page, int page_mkwrite) @@ -678,124 +675,10 @@ void throttle_vm_writeout(gfp_t gfp_mask) } } -/* - * writeback at least _min_pages, and keep writing until the amount of dirty - * memory is less than the background threshold, or until we're all clean. - */ -static void background_writeout(unsigned long _min_pages) -{ - long min_pages = _min_pages; - struct writeback_control wbc = { - .bdi = NULL, - .sync_mode = WB_SYNC_NONE, - .older_than_this = NULL, - .nr_to_write = 0, - .nonblocking = 1, - .range_cyclic = 1, - }; - - for ( ; ; ) { - unsigned long background_thresh; - unsigned long dirty_thresh; - - get_dirty_limits(&background_thresh, &dirty_thresh, NULL, NULL); - if (global_page_state(NR_FILE_DIRTY) + - global_page_state(NR_UNSTABLE_NFS) < background_thresh - && min_pages <= 0) - break; - wbc.more_io = 0; - wbc.encountered_congestion = 0; - wbc.nr_to_write = MAX_WRITEBACK_PAGES; - wbc.pages_skipped = 0; - writeback_inodes(&wbc); - min_pages -= MAX_WRITEBACK_PAGES - wbc.nr_to_write; - if (wbc.nr_to_write > 0 || wbc.pages_skipped > 0) { - /* Wrote less than expected */ - if (wbc.encountered_congestion || wbc.more_io) - congestion_wait(BLK_RW_ASYNC, HZ/10); - else - break; - } - } -} - -/* - * Start writeback of `nr_pages' pages. If `nr_pages' is zero, write back - * the whole world. Returns 0 if a pdflush thread was dispatched. Returns - * -1 if all pdflush threads were busy. - */ -int wakeup_pdflush(long nr_pages) -{ - if (nr_pages == 0) - nr_pages = global_page_state(NR_FILE_DIRTY) + - global_page_state(NR_UNSTABLE_NFS); - return pdflush_operation(background_writeout, nr_pages); -} - -static void wb_timer_fn(unsigned long unused); static void laptop_timer_fn(unsigned long unused); -static DEFINE_TIMER(wb_timer, wb_timer_fn, 0, 0); static DEFINE_TIMER(laptop_mode_wb_timer, laptop_timer_fn, 0, 0); -/* - * Periodic writeback of "old" data. - * - * Define "old": the first time one of an inode's pages is dirtied, we mark the - * dirtying-time in the inode's address_space. So this periodic writeback code - * just walks the superblock inode list, writing back any inodes which are - * older than a specific point in time. - * - * Try to run once per dirty_writeback_interval. But if a writeback event - * takes longer than a dirty_writeback_interval interval, then leave a - * one-second gap. - * - * older_than_this takes precedence over nr_to_write. So we'll only write back - * all dirty pages if they are all attached to "old" mappings. - */ -static void wb_kupdate(unsigned long arg) -{ - unsigned long oldest_jif; - unsigned long start_jif; - unsigned long next_jif; - long nr_to_write; - struct writeback_control wbc = { - .bdi = NULL, - .sync_mode = WB_SYNC_NONE, - .older_than_this = &oldest_jif, - .nr_to_write = 0, - .nonblocking = 1, - .for_kupdate = 1, - .range_cyclic = 1, - }; - - sync_supers(); - - oldest_jif = jiffies - msecs_to_jiffies(dirty_expire_interval * 10); - start_jif = jiffies; - next_jif = start_jif + msecs_to_jiffies(dirty_writeback_interval * 10); - nr_to_write = global_page_state(NR_FILE_DIRTY) + - global_page_state(NR_UNSTABLE_NFS) + - (inodes_stat.nr_inodes - inodes_stat.nr_unused); - while (nr_to_write > 0) { - wbc.more_io = 0; - wbc.encountered_congestion = 0; - wbc.nr_to_write = MAX_WRITEBACK_PAGES; - writeback_inodes(&wbc); - if (wbc.nr_to_write > 0) { - if (wbc.encountered_congestion || wbc.more_io) - congestion_wait(BLK_RW_ASYNC, HZ/10); - else - break; /* All the old data is written */ - } - nr_to_write -= MAX_WRITEBACK_PAGES - wbc.nr_to_write; - } - if (time_before(next_jif, jiffies + HZ)) - next_jif = jiffies + HZ; - if (dirty_writeback_interval) - mod_timer(&wb_timer, next_jif); -} - /* * sysctl handler for /proc/sys/vm/dirty_writeback_centisecs */ @@ -803,28 +686,24 @@ int dirty_writeback_centisecs_handler(ctl_table *table, int write, struct file *file, void __user *buffer, size_t *length, loff_t *ppos) { proc_dointvec(table, write, file, buffer, length, ppos); - if (dirty_writeback_interval) - mod_timer(&wb_timer, jiffies + - msecs_to_jiffies(dirty_writeback_interval * 10)); - else - del_timer(&wb_timer); return 0; } -static void wb_timer_fn(unsigned long unused) -{ - if (pdflush_operation(wb_kupdate, 0) < 0) - mod_timer(&wb_timer, jiffies + HZ); /* delay 1 second */ -} - -static void laptop_flush(unsigned long unused) +static void do_laptop_sync(struct work_struct *work) { - sys_sync(); + wakeup_flusher_threads(0); + kfree(work); } static void laptop_timer_fn(unsigned long unused) { - pdflush_operation(laptop_flush, 0); + struct work_struct *work; + + work = kmalloc(sizeof(*work), GFP_ATOMIC); + if (work) { + INIT_WORK(work, do_laptop_sync); + schedule_work(work); + } } /* @@ -907,8 +786,6 @@ void __init page_writeback_init(void) { int shift; - mod_timer(&wb_timer, - jiffies + msecs_to_jiffies(dirty_writeback_interval * 10)); writeback_set_ratelimit(); register_cpu_notifier(&ratelimit_nb); diff --git a/mm/vmscan.c b/mm/vmscan.c index 94e86dd6954c..ba8228e0a806 100644 --- a/mm/vmscan.c +++ b/mm/vmscan.c @@ -1720,7 +1720,7 @@ static unsigned long do_try_to_free_pages(struct zonelist *zonelist, */ if (total_scanned > sc->swap_cluster_max + sc->swap_cluster_max / 2) { - wakeup_pdflush(laptop_mode ? 0 : total_scanned); + wakeup_flusher_threads(laptop_mode ? 0 : total_scanned); sc->may_writepage = 1; } -- cgit v1.2.3-58-ga151 From d0bceac747b547c0b4769b91fec7d3c15600153f Mon Sep 17 00:00:00 2001 From: Jens Axboe Date: Mon, 18 May 2009 08:20:32 +0200 Subject: writeback: get rid of pdflush completely It is now unused, so kill it off. Signed-off-by: Jens Axboe --- fs/fs-writeback.c | 5 + include/linux/writeback.h | 12 --- mm/Makefile | 2 +- mm/pdflush.c | 269 ---------------------------------------------- 4 files changed, 6 insertions(+), 282 deletions(-) delete mode 100644 mm/pdflush.c (limited to 'include') diff --git a/fs/fs-writeback.c b/fs/fs-writeback.c index 7f6dae8aa47f..2e601ce581c9 100644 --- a/fs/fs-writeback.c +++ b/fs/fs-writeback.c @@ -29,6 +29,11 @@ #define inode_to_bdi(inode) ((inode)->i_mapping->backing_dev_info) +/* + * We don't actually have pdflush, but this one is exported though /proc... + */ +int nr_pdflush_threads; + /* * Work items for the bdi_writeback threads */ diff --git a/include/linux/writeback.h b/include/linux/writeback.h index cef75527a14c..78b1e4684cc9 100644 --- a/include/linux/writeback.h +++ b/include/linux/writeback.h @@ -13,17 +13,6 @@ extern spinlock_t inode_lock; extern struct list_head inode_in_use; extern struct list_head inode_unused; -/* - * Yes, writeback.h requires sched.h - * No, sched.h is not included from here. - */ -static inline int task_is_pdflush(struct task_struct *task) -{ - return task->flags & PF_FLUSHER; -} - -#define current_is_pdflush() task_is_pdflush(current) - /* * fs/fs-writeback.c */ @@ -155,7 +144,6 @@ balance_dirty_pages_ratelimited(struct address_space *mapping) typedef int (*writepage_t)(struct page *page, struct writeback_control *wbc, void *data); -int pdflush_operation(void (*fn)(unsigned long), unsigned long arg0); int generic_writepages(struct address_space *mapping, struct writeback_control *wbc); int write_cache_pages(struct address_space *mapping, diff --git a/mm/Makefile b/mm/Makefile index 5e0bd6426693..147a7a7873c4 100644 --- a/mm/Makefile +++ b/mm/Makefile @@ -8,7 +8,7 @@ mmu-$(CONFIG_MMU) := fremap.o highmem.o madvise.o memory.o mincore.o \ vmalloc.o obj-y := bootmem.o filemap.o mempool.o oom_kill.o fadvise.o \ - maccess.o page_alloc.o page-writeback.o pdflush.o \ + maccess.o page_alloc.o page-writeback.o \ readahead.o swap.o truncate.o vmscan.o shmem.o \ prio_tree.o util.o mmzone.o vmstat.o backing-dev.o \ page_isolation.o mm_init.o $(mmu-y) diff --git a/mm/pdflush.c b/mm/pdflush.c deleted file mode 100644 index 235ac440c44e..000000000000 --- a/mm/pdflush.c +++ /dev/null @@ -1,269 +0,0 @@ -/* - * mm/pdflush.c - worker threads for writing back filesystem data - * - * Copyright (C) 2002, Linus Torvalds. - * - * 09Apr2002 Andrew Morton - * Initial version - * 29Feb2004 kaos@sgi.com - * Move worker thread creation to kthread to avoid chewing - * up stack space with nested calls to kernel_thread. - */ - -#include -#include -#include -#include -#include -#include -#include -#include /* Needed by writeback.h */ -#include /* Prototypes pdflush_operation() */ -#include -#include -#include - - -/* - * Minimum and maximum number of pdflush instances - */ -#define MIN_PDFLUSH_THREADS 2 -#define MAX_PDFLUSH_THREADS 8 - -static void start_one_pdflush_thread(void); - - -/* - * The pdflush threads are worker threads for writing back dirty data. - * Ideally, we'd like one thread per active disk spindle. But the disk - * topology is very hard to divine at this level. Instead, we take - * care in various places to prevent more than one pdflush thread from - * performing writeback against a single filesystem. pdflush threads - * have the PF_FLUSHER flag set in current->flags to aid in this. - */ - -/* - * All the pdflush threads. Protected by pdflush_lock - */ -static LIST_HEAD(pdflush_list); -static DEFINE_SPINLOCK(pdflush_lock); - -/* - * The count of currently-running pdflush threads. Protected - * by pdflush_lock. - * - * Readable by sysctl, but not writable. Published to userspace at - * /proc/sys/vm/nr_pdflush_threads. - */ -int nr_pdflush_threads = 0; - -/* - * The time at which the pdflush thread pool last went empty - */ -static unsigned long last_empty_jifs; - -/* - * The pdflush thread. - * - * Thread pool management algorithm: - * - * - The minimum and maximum number of pdflush instances are bound - * by MIN_PDFLUSH_THREADS and MAX_PDFLUSH_THREADS. - * - * - If there have been no idle pdflush instances for 1 second, create - * a new one. - * - * - If the least-recently-went-to-sleep pdflush thread has been asleep - * for more than one second, terminate a thread. - */ - -/* - * A structure for passing work to a pdflush thread. Also for passing - * state information between pdflush threads. Protected by pdflush_lock. - */ -struct pdflush_work { - struct task_struct *who; /* The thread */ - void (*fn)(unsigned long); /* A callback function */ - unsigned long arg0; /* An argument to the callback */ - struct list_head list; /* On pdflush_list, when idle */ - unsigned long when_i_went_to_sleep; -}; - -static int __pdflush(struct pdflush_work *my_work) -{ - current->flags |= PF_FLUSHER | PF_SWAPWRITE; - set_freezable(); - my_work->fn = NULL; - my_work->who = current; - INIT_LIST_HEAD(&my_work->list); - - spin_lock_irq(&pdflush_lock); - for ( ; ; ) { - struct pdflush_work *pdf; - - set_current_state(TASK_INTERRUPTIBLE); - list_move(&my_work->list, &pdflush_list); - my_work->when_i_went_to_sleep = jiffies; - spin_unlock_irq(&pdflush_lock); - schedule(); - try_to_freeze(); - spin_lock_irq(&pdflush_lock); - if (!list_empty(&my_work->list)) { - /* - * Someone woke us up, but without removing our control - * structure from the global list. swsusp will do this - * in try_to_freeze()->refrigerator(). Handle it. - */ - my_work->fn = NULL; - continue; - } - if (my_work->fn == NULL) { - printk("pdflush: bogus wakeup\n"); - continue; - } - spin_unlock_irq(&pdflush_lock); - - (*my_work->fn)(my_work->arg0); - - spin_lock_irq(&pdflush_lock); - - /* - * Thread creation: For how long have there been zero - * available threads? - * - * To throttle creation, we reset last_empty_jifs. - */ - if (time_after(jiffies, last_empty_jifs + 1 * HZ)) { - if (list_empty(&pdflush_list)) { - if (nr_pdflush_threads < MAX_PDFLUSH_THREADS) { - last_empty_jifs = jiffies; - nr_pdflush_threads++; - spin_unlock_irq(&pdflush_lock); - start_one_pdflush_thread(); - spin_lock_irq(&pdflush_lock); - } - } - } - - my_work->fn = NULL; - - /* - * Thread destruction: For how long has the sleepiest - * thread slept? - */ - if (list_empty(&pdflush_list)) - continue; - if (nr_pdflush_threads <= MIN_PDFLUSH_THREADS) - continue; - pdf = list_entry(pdflush_list.prev, struct pdflush_work, list); - if (time_after(jiffies, pdf->when_i_went_to_sleep + 1 * HZ)) { - /* Limit exit rate */ - pdf->when_i_went_to_sleep = jiffies; - break; /* exeunt */ - } - } - nr_pdflush_threads--; - spin_unlock_irq(&pdflush_lock); - return 0; -} - -/* - * Of course, my_work wants to be just a local in __pdflush(). It is - * separated out in this manner to hopefully prevent the compiler from - * performing unfortunate optimisations against the auto variables. Because - * these are visible to other tasks and CPUs. (No problem has actually - * been observed. This is just paranoia). - */ -static int pdflush(void *dummy) -{ - struct pdflush_work my_work; - cpumask_var_t cpus_allowed; - - /* - * Since the caller doesn't even check kthread_run() worked, let's not - * freak out too much if this fails. - */ - if (!alloc_cpumask_var(&cpus_allowed, GFP_KERNEL)) { - printk(KERN_WARNING "pdflush failed to allocate cpumask\n"); - return 0; - } - - /* - * pdflush can spend a lot of time doing encryption via dm-crypt. We - * don't want to do that at keventd's priority. - */ - set_user_nice(current, 0); - - /* - * Some configs put our parent kthread in a limited cpuset, - * which kthread() overrides, forcing cpus_allowed == cpu_all_mask. - * Our needs are more modest - cut back to our cpusets cpus_allowed. - * This is needed as pdflush's are dynamically created and destroyed. - * The boottime pdflush's are easily placed w/o these 2 lines. - */ - cpuset_cpus_allowed(current, cpus_allowed); - set_cpus_allowed_ptr(current, cpus_allowed); - free_cpumask_var(cpus_allowed); - - return __pdflush(&my_work); -} - -/* - * Attempt to wake up a pdflush thread, and get it to do some work for you. - * Returns zero if it indeed managed to find a worker thread, and passed your - * payload to it. - */ -int pdflush_operation(void (*fn)(unsigned long), unsigned long arg0) -{ - unsigned long flags; - int ret = 0; - - BUG_ON(fn == NULL); /* Hard to diagnose if it's deferred */ - - spin_lock_irqsave(&pdflush_lock, flags); - if (list_empty(&pdflush_list)) { - ret = -1; - } else { - struct pdflush_work *pdf; - - pdf = list_entry(pdflush_list.next, struct pdflush_work, list); - list_del_init(&pdf->list); - if (list_empty(&pdflush_list)) - last_empty_jifs = jiffies; - pdf->fn = fn; - pdf->arg0 = arg0; - wake_up_process(pdf->who); - } - spin_unlock_irqrestore(&pdflush_lock, flags); - - return ret; -} - -static void start_one_pdflush_thread(void) -{ - struct task_struct *k; - - k = kthread_run(pdflush, NULL, "pdflush"); - if (unlikely(IS_ERR(k))) { - spin_lock_irq(&pdflush_lock); - nr_pdflush_threads--; - spin_unlock_irq(&pdflush_lock); - } -} - -static int __init pdflush_init(void) -{ - int i; - - /* - * Pre-set nr_pdflush_threads... If we fail to create, - * the count will be decremented. - */ - nr_pdflush_threads = MIN_PDFLUSH_THREADS; - - for (i = 0; i < MIN_PDFLUSH_THREADS; i++) - start_one_pdflush_thread(); - return 0; -} - -module_init(pdflush_init); -- cgit v1.2.3-58-ga151 From d993831fa7ffeb89e994f046f93eeb09ec91df08 Mon Sep 17 00:00:00 2001 From: Jens Axboe Date: Fri, 12 Jun 2009 14:45:52 +0200 Subject: writeback: add name to backing_dev_info This enables us to track who does what and print info. Its main use is catching dirty inodes on the default_backing_dev_info, so we can fix that up. Signed-off-by: Jens Axboe --- block/blk-core.c | 1 + drivers/block/aoe/aoeblk.c | 1 + drivers/char/mem.c | 1 + fs/btrfs/disk-io.c | 1 + fs/char_dev.c | 1 + fs/configfs/inode.c | 1 + fs/fuse/inode.c | 1 + fs/hugetlbfs/inode.c | 1 + fs/nfs/client.c | 1 + fs/ocfs2/dlm/dlmfs.c | 1 + fs/ramfs/inode.c | 1 + fs/sysfs/inode.c | 1 + fs/ubifs/super.c | 1 + include/linux/backing-dev.h | 2 ++ kernel/cgroup.c | 1 + mm/backing-dev.c | 1 + mm/swap_state.c | 1 + 17 files changed, 18 insertions(+) (limited to 'include') diff --git a/block/blk-core.c b/block/blk-core.c index e3299a77a0d8..e695634882a6 100644 --- a/block/blk-core.c +++ b/block/blk-core.c @@ -501,6 +501,7 @@ struct request_queue *blk_alloc_queue_node(gfp_t gfp_mask, int node_id) (VM_MAX_READAHEAD * 1024) / PAGE_CACHE_SIZE; q->backing_dev_info.state = 0; q->backing_dev_info.capabilities = BDI_CAP_MAP_COPY; + q->backing_dev_info.name = "block"; err = bdi_init(&q->backing_dev_info); if (err) { diff --git a/drivers/block/aoe/aoeblk.c b/drivers/block/aoe/aoeblk.c index 1e15889c4b98..95d344971eda 100644 --- a/drivers/block/aoe/aoeblk.c +++ b/drivers/block/aoe/aoeblk.c @@ -268,6 +268,7 @@ aoeblk_gdalloc(void *vp) if (!d->blkq) goto err_mempool; blk_queue_make_request(d->blkq, aoeblk_make_request); + d->blkq->backing_dev_info.name = "aoe"; if (bdi_init(&d->blkq->backing_dev_info)) goto err_blkq; spin_lock_irqsave(&d->lock, flags); diff --git a/drivers/char/mem.c b/drivers/char/mem.c index afa8813e737a..645237bda682 100644 --- a/drivers/char/mem.c +++ b/drivers/char/mem.c @@ -822,6 +822,7 @@ static const struct file_operations zero_fops = { * - permits private mappings, "copies" are taken of the source of zeros */ static struct backing_dev_info zero_bdi = { + .name = "char/mem", .capabilities = BDI_CAP_MAP_COPY, }; diff --git a/fs/btrfs/disk-io.c b/fs/btrfs/disk-io.c index e83be2e4602c..15831d5c7367 100644 --- a/fs/btrfs/disk-io.c +++ b/fs/btrfs/disk-io.c @@ -1352,6 +1352,7 @@ static int setup_bdi(struct btrfs_fs_info *info, struct backing_dev_info *bdi) { int err; + bdi->name = "btrfs"; bdi->capabilities = BDI_CAP_MAP_COPY; err = bdi_init(bdi); if (err) diff --git a/fs/char_dev.c b/fs/char_dev.c index a173551e19d7..7c27a8ebef6a 100644 --- a/fs/char_dev.c +++ b/fs/char_dev.c @@ -31,6 +31,7 @@ * - no readahead or I/O queue unplugging required */ struct backing_dev_info directly_mappable_cdev_bdi = { + .name = "char", .capabilities = ( #ifdef CONFIG_MMU /* permit private copies of the data to be taken */ diff --git a/fs/configfs/inode.c b/fs/configfs/inode.c index 4921e7426d95..a2f746066c5d 100644 --- a/fs/configfs/inode.c +++ b/fs/configfs/inode.c @@ -51,6 +51,7 @@ static const struct address_space_operations configfs_aops = { }; static struct backing_dev_info configfs_backing_dev_info = { + .name = "configfs", .ra_pages = 0, /* No readahead */ .capabilities = BDI_CAP_NO_ACCT_AND_WRITEBACK, }; diff --git a/fs/fuse/inode.c b/fs/fuse/inode.c index f91ccc4a189d..4567db6f9430 100644 --- a/fs/fuse/inode.c +++ b/fs/fuse/inode.c @@ -801,6 +801,7 @@ static int fuse_bdi_init(struct fuse_conn *fc, struct super_block *sb) { int err; + fc->bdi.name = "fuse"; fc->bdi.ra_pages = (VM_MAX_READAHEAD * 1024) / PAGE_CACHE_SIZE; fc->bdi.unplug_io_fn = default_unplug_io_fn; /* fuse does it's own writeback accounting */ diff --git a/fs/hugetlbfs/inode.c b/fs/hugetlbfs/inode.c index cb88dac8ccaa..a93b885311d8 100644 --- a/fs/hugetlbfs/inode.c +++ b/fs/hugetlbfs/inode.c @@ -44,6 +44,7 @@ static const struct inode_operations hugetlbfs_dir_inode_operations; static const struct inode_operations hugetlbfs_inode_operations; static struct backing_dev_info hugetlbfs_backing_dev_info = { + .name = "hugetlbfs", .ra_pages = 0, /* No readahead */ .capabilities = BDI_CAP_NO_ACCT_AND_WRITEBACK, }; diff --git a/fs/nfs/client.c b/fs/nfs/client.c index 8d25ccb2d51d..c6be84a161f6 100644 --- a/fs/nfs/client.c +++ b/fs/nfs/client.c @@ -879,6 +879,7 @@ static void nfs_server_set_fsinfo(struct nfs_server *server, struct nfs_fsinfo * server->rsize = NFS_MAX_FILE_IO_SIZE; server->rpages = (server->rsize + PAGE_CACHE_SIZE - 1) >> PAGE_CACHE_SHIFT; + server->backing_dev_info.name = "nfs"; server->backing_dev_info.ra_pages = server->rpages * NFS_MAX_READAHEAD; if (server->wsize > max_rpc_payload) diff --git a/fs/ocfs2/dlm/dlmfs.c b/fs/ocfs2/dlm/dlmfs.c index 1c9efb406a96..02bf17808bdc 100644 --- a/fs/ocfs2/dlm/dlmfs.c +++ b/fs/ocfs2/dlm/dlmfs.c @@ -325,6 +325,7 @@ clear_fields: } static struct backing_dev_info dlmfs_backing_dev_info = { + .name = "ocfs2-dlmfs", .ra_pages = 0, /* No readahead */ .capabilities = BDI_CAP_NO_ACCT_AND_WRITEBACK, }; diff --git a/fs/ramfs/inode.c b/fs/ramfs/inode.c index 0ff7566c767c..a7f0110fca4c 100644 --- a/fs/ramfs/inode.c +++ b/fs/ramfs/inode.c @@ -46,6 +46,7 @@ static const struct super_operations ramfs_ops; static const struct inode_operations ramfs_dir_inode_operations; static struct backing_dev_info ramfs_backing_dev_info = { + .name = "ramfs", .ra_pages = 0, /* No readahead */ .capabilities = BDI_CAP_NO_ACCT_AND_WRITEBACK | BDI_CAP_MAP_DIRECT | BDI_CAP_MAP_COPY | diff --git a/fs/sysfs/inode.c b/fs/sysfs/inode.c index 555f0ff988df..e57f98e54fce 100644 --- a/fs/sysfs/inode.c +++ b/fs/sysfs/inode.c @@ -29,6 +29,7 @@ static const struct address_space_operations sysfs_aops = { }; static struct backing_dev_info sysfs_backing_dev_info = { + .name = "sysfs", .ra_pages = 0, /* No readahead */ .capabilities = BDI_CAP_NO_ACCT_AND_WRITEBACK, }; diff --git a/fs/ubifs/super.c b/fs/ubifs/super.c index 8d6050a5966c..51763aa8f4de 100644 --- a/fs/ubifs/super.c +++ b/fs/ubifs/super.c @@ -1965,6 +1965,7 @@ static int ubifs_fill_super(struct super_block *sb, void *data, int silent) * * Read-ahead will be disabled because @c->bdi.ra_pages is 0. */ + c->bdi.name = "ubifs", c->bdi.capabilities = BDI_CAP_MAP_COPY; c->bdi.unplug_io_fn = default_unplug_io_fn; err = bdi_init(&c->bdi); diff --git a/include/linux/backing-dev.h b/include/linux/backing-dev.h index d045f5f615c7..2f218b7cb063 100644 --- a/include/linux/backing-dev.h +++ b/include/linux/backing-dev.h @@ -66,6 +66,8 @@ struct backing_dev_info { void (*unplug_io_fn)(struct backing_dev_info *, struct page *); void *unplug_io_data; + char *name; + struct percpu_counter bdi_stat[NR_BDI_STAT_ITEMS]; struct prop_local_percpu completions; diff --git a/kernel/cgroup.c b/kernel/cgroup.c index b6eadfe30e7b..c7ece8f027f2 100644 --- a/kernel/cgroup.c +++ b/kernel/cgroup.c @@ -600,6 +600,7 @@ static struct inode_operations cgroup_dir_inode_operations; static struct file_operations proc_cgroupstats_operations; static struct backing_dev_info cgroup_backing_dev_info = { + .name = "cgroup", .capabilities = BDI_CAP_NO_ACCT_AND_WRITEBACK, }; diff --git a/mm/backing-dev.c b/mm/backing-dev.c index 22c45e932e3a..5cb32c5b93d8 100644 --- a/mm/backing-dev.c +++ b/mm/backing-dev.c @@ -17,6 +17,7 @@ void default_unplug_io_fn(struct backing_dev_info *bdi, struct page *page) EXPORT_SYMBOL(default_unplug_io_fn); struct backing_dev_info default_backing_dev_info = { + .name = "default", .ra_pages = VM_MAX_READAHEAD * 1024 / PAGE_CACHE_SIZE, .state = 0, .capabilities = BDI_CAP_MAP_COPY, diff --git a/mm/swap_state.c b/mm/swap_state.c index 42cd38eba79f..5ae6b8b78c80 100644 --- a/mm/swap_state.c +++ b/mm/swap_state.c @@ -34,6 +34,7 @@ static const struct address_space_operations swap_aops = { }; static struct backing_dev_info swap_backing_dev_info = { + .name = "swap", .capabilities = BDI_CAP_NO_ACCT_AND_WRITEBACK | BDI_CAP_SWAP_BACKED, .unplug_io_fn = swap_unplug_io_fn, }; -- cgit v1.2.3-58-ga151 From 500b067c5e6ceea49cf280a02597b1169320e08c Mon Sep 17 00:00:00 2001 From: Jens Axboe Date: Wed, 9 Sep 2009 09:10:25 +0200 Subject: writeback: check for registered bdi in flusher add and inode dirty Also a debugging aid. We want to catch dirty inodes being added to backing devices that don't do writeback. Signed-off-by: Jens Axboe --- fs/fs-writeback.c | 8 ++++++++ include/linux/backing-dev.h | 1 + mm/backing-dev.c | 7 +++++++ 3 files changed, 16 insertions(+) (limited to 'include') diff --git a/fs/fs-writeback.c b/fs/fs-writeback.c index 2e601ce581c9..da86ef58e427 100644 --- a/fs/fs-writeback.c +++ b/fs/fs-writeback.c @@ -1046,6 +1046,14 @@ void __mark_inode_dirty(struct inode *inode, int flags) */ if (!was_dirty) { struct bdi_writeback *wb = &inode_to_bdi(inode)->wb; + struct backing_dev_info *bdi = wb->bdi; + + if (bdi_cap_writeback_dirty(bdi) && + !test_bit(BDI_registered, &bdi->state)) { + WARN_ON(1); + printk(KERN_ERR "bdi-%s not registered\n", + bdi->name); + } inode->dirtied_when = jiffies; list_move(&inode->i_list, &wb->b_dirty); diff --git a/include/linux/backing-dev.h b/include/linux/backing-dev.h index 2f218b7cb063..f169bcb90b58 100644 --- a/include/linux/backing-dev.h +++ b/include/linux/backing-dev.h @@ -29,6 +29,7 @@ enum bdi_state { BDI_wb_alloc, /* Default embedded wb allocated */ BDI_async_congested, /* The async (write) queue is getting full */ BDI_sync_congested, /* The sync queue is getting full */ + BDI_registered, /* bdi_register() was done */ BDI_unused, /* Available bits start here */ }; diff --git a/mm/backing-dev.c b/mm/backing-dev.c index 5cb32c5b93d8..d3ca0dac1111 100644 --- a/mm/backing-dev.c +++ b/mm/backing-dev.c @@ -465,6 +465,12 @@ void static bdi_add_default_flusher_task(struct backing_dev_info *bdi) if (!bdi_cap_writeback_dirty(bdi)) return; + if (WARN_ON(!test_bit(BDI_registered, &bdi->state))) { + printk(KERN_ERR "bdi %p/%s is not registered!\n", + bdi, bdi->name); + return; + } + /* * Check with the helper whether to proceed adding a task. Will only * abort if we two or more simultanous calls to @@ -528,6 +534,7 @@ int bdi_register(struct backing_dev_info *bdi, struct device *parent, } bdi_debug_register(bdi, dev_name(dev)); + set_bit(BDI_registered, &bdi->state); exit: return ret; } -- cgit v1.2.3-58-ga151