* [PATCH 01/12] Move the default_backing_dev_info out of readahead.c and into backing-dev.c
2009-03-22 19:25 [PATCH 0/12] Per-bdi writeback flusher threads #2 Jens Axboe
@ 2009-03-22 19:25 ` Jens Axboe
2009-03-22 19:25 ` [PATCH 02/12] btrfs: get rid of current_is_pdflush() in btrfs_btree_balance_dirty Jens Axboe
` (10 subsequent siblings)
11 siblings, 0 replies; 16+ messages in thread
From: Jens Axboe @ 2009-03-22 19:25 UTC (permalink / raw)
To: linux-kernel, linux-fsdevel
Cc: chris.mason, david, npiggin, hch, akpm, Jens Axboe
It really makes no sense to have it in readahead.c, so move it where
it belongs.
Signed-off-by: Jens Axboe <jens.axboe@oracle.com>
---
mm/backing-dev.c | 26 +++++++++++++++++++++++++-
mm/readahead.c | 25 -------------------------
2 files changed, 25 insertions(+), 26 deletions(-)
diff --git a/mm/backing-dev.c b/mm/backing-dev.c
index 8e85874..be68c95 100644
--- a/mm/backing-dev.c
+++ b/mm/backing-dev.c
@@ -2,11 +2,24 @@
#include <linux/wait.h>
#include <linux/backing-dev.h>
#include <linux/fs.h>
+#include <linux/pagemap.h>
#include <linux/sched.h>
#include <linux/module.h>
#include <linux/writeback.h>
#include <linux/device.h>
+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 = {
+ .ra_pages = VM_MAX_READAHEAD * 1024 / PAGE_CACHE_SIZE,
+ .state = 0,
+ .capabilities = BDI_CAP_MAP_COPY,
+ .unplug_io_fn = default_unplug_io_fn,
+};
+EXPORT_SYMBOL_GPL(default_backing_dev_info);
static struct class *bdi_class;
@@ -166,9 +179,20 @@ static __init int bdi_class_init(void)
bdi_debug_init();
return 0;
}
-
postcore_initcall(bdi_class_init);
+static int __init default_bdi_init(void)
+{
+ int err;
+
+ err = bdi_init(&default_backing_dev_info);
+ if (!err)
+ bdi_register(&default_backing_dev_info, NULL, "default");
+
+ return err;
+}
+subsys_initcall(default_bdi_init);
+
int bdi_register(struct backing_dev_info *bdi, struct device *parent,
const char *fmt, ...)
{
diff --git a/mm/readahead.c b/mm/readahead.c
index bec83c1..9ce303d 100644
--- a/mm/readahead.c
+++ b/mm/readahead.c
@@ -17,19 +17,6 @@
#include <linux/pagevec.h>
#include <linux/pagemap.h>
-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 = {
- .ra_pages = VM_MAX_READAHEAD * 1024 / PAGE_CACHE_SIZE,
- .state = 0,
- .capabilities = BDI_CAP_MAP_COPY,
- .unplug_io_fn = default_unplug_io_fn,
-};
-EXPORT_SYMBOL_GPL(default_backing_dev_info);
-
/*
* Initialise a struct file's readahead state. Assumes that the caller has
* memset *ra to zero.
@@ -233,18 +220,6 @@ unsigned long max_sane_readahead(unsigned long nr)
+ node_page_state(numa_node_id(), NR_FREE_PAGES)) / 2);
}
-static int __init readahead_init(void)
-{
- int err;
-
- err = bdi_init(&default_backing_dev_info);
- if (!err)
- bdi_register(&default_backing_dev_info, NULL, "default");
-
- return err;
-}
-subsys_initcall(readahead_init);
-
/*
* Submit IO for the read-ahead request in file_ra_state.
*/
--
1.6.2.12.g83676
^ permalink raw reply related [flat|nested] 16+ messages in thread* [PATCH 02/12] btrfs: get rid of current_is_pdflush() in btrfs_btree_balance_dirty
2009-03-22 19:25 [PATCH 0/12] Per-bdi writeback flusher threads #2 Jens Axboe
2009-03-22 19:25 ` [PATCH 01/12] Move the default_backing_dev_info out of readahead.c and into backing-dev.c Jens Axboe
@ 2009-03-22 19:25 ` Jens Axboe
2009-03-22 19:25 ` [PATCH 03/12] Get rid of pdflush_operation() in emergency sync and remount Jens Axboe
` (9 subsequent siblings)
11 siblings, 0 replies; 16+ messages in thread
From: Jens Axboe @ 2009-03-22 19:25 UTC (permalink / raw)
To: linux-kernel, linux-fsdevel
Cc: chris.mason, david, npiggin, hch, akpm, Jens Axboe
Chris says it's safe to kill.
Acked-by: Chris Mason <chris.mason@oracle.com>
Signed-off-by: Jens Axboe <jens.axboe@oracle.com>
---
fs/btrfs/disk-io.c | 2 +-
1 files changed, 1 insertions(+), 1 deletions(-)
diff --git a/fs/btrfs/disk-io.c b/fs/btrfs/disk-io.c
index 3e18175..6ec80c0 100644
--- a/fs/btrfs/disk-io.c
+++ b/fs/btrfs/disk-io.c
@@ -2385,7 +2385,7 @@ void btrfs_btree_balance_dirty(struct btrfs_root *root, unsigned long nr)
unsigned long thresh = 32 * 1024 * 1024;
tree = &BTRFS_I(root->fs_info->btree_inode)->io_tree;
- if (current_is_pdflush() || current->flags & PF_MEMALLOC)
+ if (current->flags & PF_MEMALLOC)
return;
num_dirty = count_range_bits(tree, &start, (u64)-1,
--
1.6.2.12.g83676
^ permalink raw reply related [flat|nested] 16+ messages in thread* [PATCH 03/12] Get rid of pdflush_operation() in emergency sync and remount
2009-03-22 19:25 [PATCH 0/12] Per-bdi writeback flusher threads #2 Jens Axboe
2009-03-22 19:25 ` [PATCH 01/12] Move the default_backing_dev_info out of readahead.c and into backing-dev.c Jens Axboe
2009-03-22 19:25 ` [PATCH 02/12] btrfs: get rid of current_is_pdflush() in btrfs_btree_balance_dirty Jens Axboe
@ 2009-03-22 19:25 ` Jens Axboe
2009-03-22 19:25 ` [PATCH 04/12] writeback: move dirty inodes from super_block to backing_dev_info Jens Axboe
` (8 subsequent siblings)
11 siblings, 0 replies; 16+ messages in thread
From: Jens Axboe @ 2009-03-22 19:25 UTC (permalink / raw)
To: linux-kernel, linux-fsdevel
Cc: chris.mason, david, npiggin, hch, akpm, Jens Axboe
Opencode a cheasy approach with kevent. The idea here is that we'll
add some generic delayed work infrastructure, which probably wont be
based on pdflush (or maybe it will, in which case we can just add it
back).
This is in preparation for getting rid of pdflush completely.
Signed-off-by: Jens Axboe <jens.axboe@oracle.com>
---
fs/super.c | 11 +++++++++--
fs/sync.c | 14 +++++++++++++-
2 files changed, 22 insertions(+), 3 deletions(-)
diff --git a/fs/super.c b/fs/super.c
index 6ce5014..dd4acb1 100644
--- a/fs/super.c
+++ b/fs/super.c
@@ -674,7 +674,7 @@ int do_remount_sb(struct super_block *sb, int flags, void *data, int force)
return 0;
}
-static void do_emergency_remount(unsigned long foo)
+static void do_emergency_remount(struct work_struct *work)
{
struct super_block *sb;
@@ -697,12 +697,19 @@ static void do_emergency_remount(unsigned long foo)
spin_lock(&sb_lock);
}
spin_unlock(&sb_lock);
+ kfree(work);
printk("Emergency Remount complete\n");
}
void emergency_remount(void)
{
- pdflush_operation(do_emergency_remount, 0);
+ struct work_struct *work;
+
+ work = kmalloc(sizeof(*work), GFP_ATOMIC);
+ if (work) {
+ INIT_WORK(work, do_emergency_remount);
+ schedule_work(work);
+ }
}
/*
diff --git a/fs/sync.c b/fs/sync.c
index a16d53e..ec95a69 100644
--- a/fs/sync.c
+++ b/fs/sync.c
@@ -42,9 +42,21 @@ SYSCALL_DEFINE0(sync)
return 0;
}
+static void do_sync_work(struct work_struct *work)
+{
+ do_sync(0);
+ kfree(work);
+}
+
void emergency_sync(void)
{
- pdflush_operation(do_sync, 0);
+ struct work_struct *work;
+
+ work = kmalloc(sizeof(*work), GFP_ATOMIC);
+ if (work) {
+ INIT_WORK(work, do_sync_work);
+ schedule_work(work);
+ }
}
/*
--
1.6.2.12.g83676
^ permalink raw reply related [flat|nested] 16+ messages in thread* [PATCH 04/12] writeback: move dirty inodes from super_block to backing_dev_info
2009-03-22 19:25 [PATCH 0/12] Per-bdi writeback flusher threads #2 Jens Axboe
` (2 preceding siblings ...)
2009-03-22 19:25 ` [PATCH 03/12] Get rid of pdflush_operation() in emergency sync and remount Jens Axboe
@ 2009-03-22 19:25 ` Jens Axboe
2009-03-22 19:25 ` [PATCH 05/12] writeback: switch to per-bdi threads for flushing data Jens Axboe
` (7 subsequent siblings)
11 siblings, 0 replies; 16+ messages in thread
From: Jens Axboe @ 2009-03-22 19:25 UTC (permalink / raw)
To: linux-kernel, linux-fsdevel
Cc: chris.mason, david, npiggin, hch, akpm, Jens Axboe
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 <jens.axboe@oracle.com>
---
fs/fs-writeback.c | 186 +++++++++++++++++++++++++++----------------
fs/super.c | 3 -
include/linux/backing-dev.h | 9 ++
include/linux/fs.h | 5 +-
mm/backing-dev.c | 30 +++++++
mm/page-writeback.c | 1 -
6 files changed, 156 insertions(+), 78 deletions(-)
diff --git a/fs/fs-writeback.c b/fs/fs-writeback.c
index e3fe991..45d2739 100644
--- a/fs/fs-writeback.c
+++ b/fs/fs-writeback.c
@@ -25,6 +25,7 @@
#include <linux/buffer_head.h>
#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
@@ -158,12 +159,13 @@ 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:
@@ -184,31 +186,30 @@ 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_after_eq(inode->dirtied_when,
- tail_inode->dirtied_when))
+ tail = list_entry(bdi->b_dirty.next, struct inode, i_list);
+ if (!time_after_eq(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)
@@ -240,18 +241,50 @@ 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(&sb->s_more_io, sb->s_io.prev);
- move_expired_inodes(&sb->s_dirty, &sb->s_io, 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)
+{
+ 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
+ */
+ rcu_read_lock();
+ list_for_each_entry_rcu(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;
+ }
+ }
+ rcu_read_unlock();
+
+ return ret;
}
EXPORT_SYMBOL(sb_has_dirty_inodes);
@@ -307,11 +340,11 @@ __sync_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
@@ -321,7 +354,7 @@ __sync_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;
@@ -387,10 +420,10 @@ __writeback_single_inode(struct inode *inode, struct writeback_control *wbc)
if ((wbc->sync_mode != WB_SYNC_ALL) && (inode->i_state & I_SYNC)) {
/*
* We're skipping this inode because it's locked, and we're not
- * doing writeback-for-data-integrity. Move it to s_more_io so
- * that writeback can proceed with the other inodes on s_io.
+ * doing writeback-for-data-integrity. Move it to b_more_io so
+ * that writeback can proceed with the other inodes on b_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.
*/
requeue_io(inode);
return 0;
@@ -413,51 +446,24 @@ __writeback_single_inode(struct inode *inode, struct writeback_control *wbc)
return __sync_single_inode(inode, 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.
- *
- * 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.
- */
-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,
+ int is_blkdev)
{
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);
+ if (!wbc->for_kupdate || list_empty(&bdi->b_io))
+ queue_io(bdi, wbc->older_than_this);
- while (!list_empty(&sb->s_io)) {
- struct inode *inode = list_entry(sb->s_io.prev,
+ 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;
if (!bdi_cap_writeback_dirty(bdi)) {
redirty_tail(inode);
- if (sb_is_blkdev_sb(sb)) {
+ if (is_blkdev) {
/*
* Dirty memory-backed blockdev: the ramdisk
* driver does this. Skip just this inode
@@ -479,14 +485,14 @@ 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)
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)
break; /* fs has the wrong queue */
requeue_io(inode);
continue; /* blockdev has wrong queue */
@@ -521,13 +527,55 @@ 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.
+ */
+void generic_sync_sb_inodes(struct super_block *sb,
+ struct writeback_control *wbc)
+{
+ const int is_blkdev = sb_is_blkdev_sb(sb);
+ struct backing_dev_info *bdi;
+
+ rcu_read_lock();
+ list_for_each_entry_rcu(bdi, &bdi_list, bdi_list)
+ generic_sync_bdi_inodes(bdi, wbc, is_blkdev);
+ rcu_read_unlock();
+
+ 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
@@ -564,10 +612,8 @@ 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 */
}
EXPORT_SYMBOL_GPL(generic_sync_sb_inodes);
@@ -582,8 +628,8 @@ static void 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 dd4acb1..e4ec03f 100644
--- a/fs/super.c
+++ b/fs/super.c
@@ -64,9 +64,6 @@ 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 bee52ab..bb58c95 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 spinlock_t 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 92734c0..3c90eb4 100644
--- a/include/linux/fs.h
+++ b/include/linux/fs.h
@@ -648,7 +648,7 @@ static inline int mapping_writably_mapped(struct address_space *mapping)
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;
@@ -1155,9 +1155,6 @@ 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 be68c95..82be036 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_SPINLOCK(bdi_lock);
+LIST_HEAD(bdi_list);
#ifdef CONFIG_DEBUG_FS
#include <linux/debugfs.h>
@@ -211,6 +213,10 @@ int bdi_register(struct backing_dev_info *bdi, struct device *parent,
goto exit;
}
+ spin_lock(&bdi_lock);
+ list_add_tail_rcu(&bdi->bdi_list, &bdi_list);
+ spin_unlock(&bdi_lock);
+
bdi->dev = dev;
bdi_debug_register(bdi, dev_name(dev));
@@ -225,9 +231,23 @@ 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)
+{
+ spin_lock(&bdi_lock);
+ list_del_rcu(&bdi->bdi_list);
+ spin_unlock(&bdi_lock);
+
+ /*
+ * In case the bdi is freed right after unregister, we need to
+ * make sure any RCU sections have exited
+ */
+ synchronize_rcu();
+}
+
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 +265,10 @@ 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 +283,8 @@ 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 +295,10 @@ 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 74dc57c..3ec11d8 100644
--- a/mm/page-writeback.c
+++ b/mm/page-writeback.c
@@ -319,7 +319,6 @@ static void task_dirty_limit(struct task_struct *tsk, 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)
--
1.6.2.12.g83676
^ permalink raw reply related [flat|nested] 16+ messages in thread* [PATCH 05/12] writeback: switch to per-bdi threads for flushing data
2009-03-22 19:25 [PATCH 0/12] Per-bdi writeback flusher threads #2 Jens Axboe
` (3 preceding siblings ...)
2009-03-22 19:25 ` [PATCH 04/12] writeback: move dirty inodes from super_block to backing_dev_info Jens Axboe
@ 2009-03-22 19:25 ` Jens Axboe
2009-03-31 14:11 ` Jan Kara
2009-03-22 19:25 ` [PATCH 06/12] writeback get rid of pdflush completely Jens Axboe
` (6 subsequent siblings)
11 siblings, 1 reply; 16+ messages in thread
From: Jens Axboe @ 2009-03-22 19:25 UTC (permalink / raw)
To: linux-kernel, linux-fsdevel
Cc: chris.mason, david, npiggin, hch, akpm, Jens Axboe
This gets rid of pdflush for bdi writeout and kupdated style cleaning.
This is an experiment to see if we get better writeout behaviour with
per-bdi flushing. Some initial tests look pretty encouraging. 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
So apart from seemingly behaving better for buffered writeout, this also
allows us to potentially have more than one bdi thread flushing out data.
This may be useful for NUMA type setups.
A 10 disk test with btrfs performs 26% faster with per-bdi flushing. Other
tests pending.
Signed-off-by: Jens Axboe <jens.axboe@oracle.com>
---
fs/buffer.c | 2 +-
fs/fs-writeback.c | 314 ++++++++++++++++++++++++++-----------------
fs/ntfs/super.c | 32 +----
fs/sync.c | 2 +-
include/linux/backing-dev.h | 23 +++
include/linux/fs.h | 3 +-
include/linux/writeback.h | 2 +-
mm/backing-dev.c | 194 +++++++++++++++++++++++++--
mm/page-writeback.c | 139 +------------------
mm/vmscan.c | 2 +-
10 files changed, 414 insertions(+), 299 deletions(-)
diff --git a/fs/buffer.c b/fs/buffer.c
index 891e1c7..76102d5 100644
--- a/fs/buffer.c
+++ b/fs/buffer.c
@@ -426,7 +426,7 @@ 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 45d2739..21de5ac 100644
--- a/fs/fs-writeback.c
+++ b/fs/fs-writeback.c
@@ -19,6 +19,8 @@
#include <linux/sched.h>
#include <linux/fs.h>
#include <linux/mm.h>
+#include <linux/kthread.h>
+#include <linux/freezer.h>
#include <linux/writeback.h>
#include <linux/blkdev.h>
#include <linux/backing-dev.h>
@@ -61,10 +63,180 @@ int writeback_in_progress(struct backing_dev_info *bdi)
*/
static void writeback_release(struct backing_dev_info *bdi)
{
- BUG_ON(!writeback_in_progress(bdi));
+ WARN_ON_ONCE(!writeback_in_progress(bdi));
+ bdi->wb_arg.nr_pages = 0;
+ bdi->wb_arg.sb = NULL;
clear_bit(BDI_pdflush, &bdi->state);
}
+int bdi_start_writeback(struct backing_dev_info *bdi, struct super_block *sb,
+ long nr_pages)
+{
+ /*
+ * This only happens the first time someone kicks this bdi, so put
+ * it out-of-line.
+ */
+ if (unlikely(!bdi->task)) {
+ bdi_add_flusher_task(bdi);
+ return 1;
+ }
+
+ if (writeback_acquire(bdi)) {
+ bdi->wb_arg.nr_pages = nr_pages;
+ bdi->wb_arg.sb = sb;
+ /*
+ * make above store seen before the task is woken
+ */
+ smp_mb();
+ wake_up(&bdi->wait);
+ }
+
+ return 0;
+}
+
+/*
+ * 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
+
+/*
+ * 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 bdi_kupdated(struct backing_dev_info *bdi)
+{
+ long nr_to_write;
+ struct writeback_control wbc = {
+ .bdi = bdi,
+ .sync_mode = WB_SYNC_NONE,
+ .nr_to_write = 0,
+ .for_kupdate = 1,
+ .range_cyclic = 1,
+ };
+
+ sync_supers();
+
+ 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;
+ generic_sync_bdi_inodes(NULL, &wbc);
+ if (wbc.nr_to_write > 0)
+ break; /* All the old data is written */
+ nr_to_write -= MAX_WRITEBACK_PAGES;
+ }
+}
+
+static void bdi_pdflush(struct backing_dev_info *bdi)
+{
+ struct writeback_control wbc = {
+ .bdi = bdi,
+ .sync_mode = WB_SYNC_NONE,
+ .older_than_this = NULL,
+ .range_cyclic = 1,
+ };
+ long nr_pages = bdi->wb_arg.nr_pages;
+
+ for (;;) {
+ unsigned long background_thresh, 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) &&
+ nr_pages <= 0)
+ break;
+
+ wbc.more_io = 0;
+ wbc.encountered_congestion = 0;
+ wbc.nr_to_write = MAX_WRITEBACK_PAGES;
+ wbc.pages_skipped = 0;
+ generic_sync_bdi_inodes(bdi->wb_arg.sb, &wbc);
+ nr_pages -= 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)
+ continue;
+ break;
+ }
+ }
+}
+
+/*
+ * 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 backing_dev_info *bdi)
+{
+ while (!kthread_should_stop()) {
+ DEFINE_WAIT(wait);
+
+ prepare_to_wait(&bdi->wait, &wait, TASK_INTERRUPTIBLE);
+ schedule_timeout(dirty_writeback_interval);
+ try_to_freeze();
+
+ /*
+ * We get here in two cases:
+ *
+ * schedule_timeout() returned because the dirty writeback
+ * interval has elapsed. If that happens, we will be able
+ * to acquire the writeback lock and will proceed to do
+ * kupdated style writeout.
+ *
+ * Someone called bdi_start_writeback(), which will acquire
+ * the writeback lock. This means our writeback_acquire()
+ * below will fail and we call into bdi_pdflush() for
+ * pdflush style writeout.
+ *
+ */
+ if (writeback_acquire(bdi))
+ bdi_kupdated(bdi);
+ else
+ bdi_pdflush(bdi);
+
+ writeback_release(bdi);
+ finish_wait(&bdi->wait, &wait);
+ }
+
+ return 0;
+}
+
+void bdi_writeback_all(struct super_block *sb, long nr_pages)
+{
+ struct backing_dev_info *bdi;
+
+ rcu_read_lock();
+
+restart:
+ list_for_each_entry_rcu(bdi, &bdi_list, bdi_list) {
+ if (!bdi_has_dirty_io(bdi))
+ continue;
+ if (bdi_start_writeback(bdi, sb, nr_pages))
+ goto restart;
+ }
+
+ rcu_read_unlock();
+}
+
/**
* __mark_inode_dirty - internal function
* @inode: inode to mark
@@ -248,46 +420,6 @@ static void queue_io(struct backing_dev_info *bdi,
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)
-{
- 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)
-{
- 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
- */
- rcu_read_lock();
- list_for_each_entry_rcu(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;
- }
- }
- rcu_read_unlock();
-
- return ret;
-}
-EXPORT_SYMBOL(sb_has_dirty_inodes);
-
/*
* Write a single inode's dirty pages and inode data out to disk.
* If `wait' is set, wait on the writeout.
@@ -446,10 +578,11 @@ __writeback_single_inode(struct inode *inode, struct writeback_control *wbc)
return __sync_single_inode(inode, wbc);
}
-static void generic_sync_bdi_inodes(struct backing_dev_info *bdi,
- struct writeback_control *wbc,
- int is_blkdev)
+void generic_sync_bdi_inodes(struct super_block *sb,
+ struct writeback_control *wbc)
{
+ const int is_blkdev_sb = sb_is_blkdev_sb(sb);
+ struct backing_dev_info *bdi = wbc->bdi;
const unsigned long start = jiffies; /* livelock avoidance */
spin_lock(&inode_lock);
@@ -461,9 +594,17 @@ static void generic_sync_bdi_inodes(struct backing_dev_info *bdi,
struct inode, i_list);
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 (is_blkdev) {
+ if (is_blkdev_sb) {
/*
* Dirty memory-backed blockdev: the ramdisk
* driver does this. Skip just this inode
@@ -485,33 +626,20 @@ static void generic_sync_bdi_inodes(struct backing_dev_info *bdi,
if (wbc->nonblocking && bdi_write_congested(bdi)) {
wbc->encountered_congestion = 1;
- if (!is_blkdev)
+ if (!is_blkdev_sb)
break; /* Skip a congested fs */
requeue_io(inode);
continue; /* Skip a congested blockdev */
}
- if (wbc->bdi && bdi != wbc->bdi) {
- if (!is_blkdev)
- break; /* fs has the wrong queue */
- requeue_io(inode);
- continue; /* blockdev has wrong queue */
- }
-
/* Was this inode dirtied after sync_sb_inodes was called? */
if (time_after(inode->dirtied_when, start))
break;
- /* Is another pdflush already flushing this queue? */
- if (current_is_pdflush() && !writeback_acquire(bdi))
- break;
-
BUG_ON(inode->i_state & I_FREEING);
__iget(inode);
pages_skipped = wbc->pages_skipped;
__writeback_single_inode(inode, wbc);
- if (current_is_pdflush())
- writeback_release(bdi);
if (wbc->pages_skipped != pages_skipped) {
/*
* writeback is not making progress due to locked
@@ -550,11 +678,6 @@ static void generic_sync_bdi_inodes(struct backing_dev_info *bdi,
* 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
@@ -563,13 +686,10 @@ static void generic_sync_bdi_inodes(struct backing_dev_info *bdi,
void generic_sync_sb_inodes(struct super_block *sb,
struct writeback_control *wbc)
{
- const int is_blkdev = sb_is_blkdev_sb(sb);
- struct backing_dev_info *bdi;
-
- rcu_read_lock();
- list_for_each_entry_rcu(bdi, &bdi_list, bdi_list)
- generic_sync_bdi_inodes(bdi, wbc, is_blkdev);
- rcu_read_unlock();
+ if (wbc->bdi)
+ bdi_start_writeback(wbc->bdi, sb, 0);
+ else
+ bdi_writeback_all(sb, 0);
if (wbc->sync_mode == WB_SYNC_ALL) {
struct inode *inode, *old_inode = NULL;
@@ -624,58 +744,6 @@ static void sync_sb_inodes(struct super_block *sb,
}
/*
- * Start writeback of dirty pagecache data against all unlocked inodes.
- *
- * 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.
- *
- * If `older_than_this' is non-zero then only flush inodes which have a
- * flushtime older than *older_than_this.
- *
- * 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...
- */
-void
-writeback_inodes(struct writeback_control *wbc)
-{
- struct super_block *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)
- sync_sb_inodes(sb, wbc);
- up_read(&sb->s_umount);
- }
- spin_lock(&sb_lock);
- if (__put_super_and_need_restart(sb))
- goto restart;
- }
- if (wbc->nr_to_write <= 0)
- break;
- }
- spin_unlock(&sb_lock);
-}
-
-/*
* writeback and wait upon the filesystem's dirty inodes. The caller will
* do this in two passes - one to write, and one to wait.
*
diff --git a/fs/ntfs/super.c b/fs/ntfs/super.c
index 4a46743..ffa4853 100644
--- a/fs/ntfs/super.c
+++ b/fs/ntfs/super.c
@@ -2373,39 +2373,13 @@ static void ntfs_put_super(struct super_block *sb)
vol->mftmirr_ino = NULL;
}
/*
- * If any dirty inodes are left, throw away all mft data page cache
- * pages to allow a clean umount. This should never happen any more
- * due to mft.c::ntfs_mft_writepage() cleaning all the dirty pages as
- * the underlying mft records are written out and cleaned. If it does,
+ * We should have no dirty inodes left, due to
+ * mft.c::ntfs_mft_writepage() cleaning all the dirty pages as
+ * the underlying mft records are written out and cleaned.
* happen anyway, we want to know...
*/
ntfs_commit_inode(vol->mft_ino);
write_inode_now(vol->mft_ino, 1);
- if (sb_has_dirty_inodes(sb)) {
- const char *s1, *s2;
-
- mutex_lock(&vol->mft_ino->i_mutex);
- truncate_inode_pages(vol->mft_ino->i_mapping, 0);
- mutex_unlock(&vol->mft_ino->i_mutex);
- write_inode_now(vol->mft_ino, 1);
- if (sb_has_dirty_inodes(sb)) {
- static const char *_s1 = "inodes";
- static const char *_s2 = "";
- s1 = _s1;
- s2 = _s2;
- } else {
- static const char *_s1 = "mft pages";
- static const char *_s2 = "They have been thrown "
- "away. ";
- s1 = _s1;
- s2 = _s2;
- }
- ntfs_error(sb, "Dirty %s found at umount time. %sYou should "
- "run chkdsk. Please email "
- "linux-ntfs-dev@lists.sourceforge.net and say "
- "that you saw this message. Thank you.", s1,
- s2);
- }
#endif /* NTFS_RW */
iput(vol->mft_ino);
diff --git a/fs/sync.c b/fs/sync.c
index ec95a69..4552be6 100644
--- a/fs/sync.c
+++ b/fs/sync.c
@@ -23,7 +23,7 @@
*/
static void do_sync(unsigned long wait)
{
- wakeup_pdflush(0);
+ wakeup_flusher_threads(0);
sync_inodes(0); /* All mappings, inodes and their blockdevs */
DQUOT_SYNC(NULL);
sync_supers(); /* Write the superblocks */
diff --git a/include/linux/backing-dev.h b/include/linux/backing-dev.h
index bb58c95..b9e2085 100644
--- a/include/linux/backing-dev.h
+++ b/include/linux/backing-dev.h
@@ -24,6 +24,7 @@ struct dentry;
*/
enum bdi_state {
BDI_pdflush, /* A pdflush thread is working this device */
+ BDI_pending, /* On its way to being activated */
BDI_write_congested, /* The write queue is getting full */
BDI_read_congested, /* The read queue is getting full */
BDI_unused, /* Available bits start here */
@@ -39,8 +40,14 @@ enum bdi_stat_item {
#define BDI_STAT_BATCH (8*(1+ilog2(nr_cpu_ids)))
+struct bdi_writeback_arg {
+ unsigned long nr_pages;
+ struct super_block *sb;
+};
+
struct backing_dev_info {
struct list_head bdi_list;
+ struct rcu_head rcu_head;
unsigned long ra_pages; /* max readahead in PAGE_CACHE_SIZE units */
unsigned long state; /* Always use atomic bitops on this */
@@ -60,6 +67,9 @@ struct backing_dev_info {
struct device *dev;
+ struct task_struct *task; /* writeback task */
+ wait_queue_head_t wait;
+ struct bdi_writeback_arg wb_arg; /* protected by BDI_pdflush */
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 */
@@ -77,10 +87,22 @@ 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);
+int bdi_start_writeback(struct backing_dev_info *bdi, struct super_block *sb,
+ long nr_pages);
+int bdi_writeback_task(struct backing_dev_info *bdi);
+void bdi_writeback_all(struct super_block *sb, long nr_pages);
+void bdi_add_flusher_task(struct backing_dev_info *bdi);
extern spinlock_t bdi_lock;
extern struct list_head bdi_list;
+static inline int bdi_has_dirty_io(struct backing_dev_info *bdi)
+{
+ return !list_empty(&bdi->b_dirty) ||
+ !list_empty(&bdi->b_io) ||
+ !list_empty(&bdi->b_more_io);
+}
+
static inline void __add_bdi_stat(struct backing_dev_info *bdi,
enum bdi_stat_item item, s64 amount)
{
@@ -196,6 +218,7 @@ int bdi_set_max_ratio(struct backing_dev_info *bdi, unsigned int max_ratio);
#define BDI_CAP_EXEC_MAP 0x00000040
#define BDI_CAP_NO_ACCT_WB 0x00000080
#define BDI_CAP_SWAP_BACKED 0x00000100
+#define BDI_CAP_FLUSH_FORKER 0x00000200
#define BDI_CAP_VMFLAGS \
(BDI_CAP_READ_MAP | BDI_CAP_WRITE_MAP | BDI_CAP_EXEC_MAP)
diff --git a/include/linux/fs.h b/include/linux/fs.h
index 3c90eb4..7d44bda 100644
--- a/include/linux/fs.h
+++ b/include/linux/fs.h
@@ -1832,6 +1832,8 @@ 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 void generic_sync_bdi_inodes(struct super_block *sb,
+ struct writeback_control *);
extern int write_inode_now(struct inode *, int);
extern int filemap_fdatawrite(struct address_space *);
extern int filemap_flush(struct address_space *);
@@ -1950,7 +1952,6 @@ 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 7300ecd..3697e91 100644
--- a/include/linux/writeback.h
+++ b/include/linux/writeback.h
@@ -99,7 +99,7 @@ static inline void inode_sync_wait(struct inode *inode)
/*
* mm/page-writeback.c
*/
-int wakeup_pdflush(long nr_pages);
+int wakeup_flusher_threads(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 82be036..b4a74d3 100644
--- a/mm/backing-dev.c
+++ b/mm/backing-dev.c
@@ -1,8 +1,11 @@
#include <linux/wait.h>
#include <linux/backing-dev.h>
+#include <linux/kthread.h>
+#include <linux/freezer.h>
#include <linux/fs.h>
#include <linux/pagemap.h>
+#include <linux/mm.h>
#include <linux/sched.h>
#include <linux/module.h>
#include <linux/writeback.h>
@@ -16,7 +19,7 @@ EXPORT_SYMBOL(default_unplug_io_fn);
struct backing_dev_info default_backing_dev_info = {
.ra_pages = VM_MAX_READAHEAD * 1024 / PAGE_CACHE_SIZE,
.state = 0,
- .capabilities = BDI_CAP_MAP_COPY,
+ .capabilities = BDI_CAP_MAP_COPY | BDI_CAP_FLUSH_FORKER,
.unplug_io_fn = default_unplug_io_fn,
};
EXPORT_SYMBOL_GPL(default_backing_dev_info);
@@ -24,6 +27,7 @@ EXPORT_SYMBOL_GPL(default_backing_dev_info);
static struct class *bdi_class;
DEFINE_SPINLOCK(bdi_lock);
LIST_HEAD(bdi_list);
+LIST_HEAD(bdi_pending_list);
#ifdef CONFIG_DEBUG_FS
#include <linux/debugfs.h>
@@ -195,6 +199,146 @@ static int __init default_bdi_init(void)
}
subsys_initcall(default_bdi_init);
+static int bdi_start_fn(void *ptr)
+{
+ struct backing_dev_info *bdi = ptr;
+ struct task_struct *tsk = current;
+
+ /*
+ * Add us to the active bdi_list
+ */
+ spin_lock_bh(&bdi_lock);
+ list_add_rcu(&bdi->bdi_list, &bdi_list);
+ spin_unlock_bh(&bdi_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);
+
+ /*
+ * Clear pending bit and wakeup anybody waiting to tear us down
+ */
+ clear_bit(BDI_pending, &bdi->state);
+ wake_up_bit(&bdi->state, BDI_pending);
+
+ return bdi_writeback_task(bdi);
+}
+
+static int bdi_forker_task(void *ptr)
+{
+ struct backing_dev_info *bdi, *me = ptr;
+
+ for (;;) {
+ DEFINE_WAIT(wait);
+
+ /*
+ * Should never trigger on the default bdi
+ */
+ WARN_ON(bdi_has_dirty_io(me));
+
+ prepare_to_wait(&me->wait, &wait, TASK_INTERRUPTIBLE);
+ smp_mb();
+ if (list_empty(&bdi_pending_list))
+ schedule();
+ else {
+repeat:
+ bdi = NULL;
+
+ spin_lock_bh(&bdi_lock);
+ if (!list_empty(&bdi_pending_list)) {
+ bdi = list_entry(bdi_pending_list.next,
+ struct backing_dev_info,
+ bdi_list);
+ list_del_init(&bdi->bdi_list);
+ }
+ spin_unlock_bh(&bdi_lock);
+
+ /*
+ * If no bdi or bdi already got setup, continue
+ */
+ if (!bdi || bdi->task)
+ continue;
+
+ bdi->task = kthread_run(bdi_start_fn, bdi, "bdi-%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 (!bdi->task) {
+ struct writeback_control wbc = {
+ .bdi = bdi,
+ .sync_mode = WB_SYNC_NONE,
+ .older_than_this = NULL,
+ .range_cyclic = 1,
+ };
+
+ /*
+ * Add this 'bdi' to the back, so we get
+ * a chance to flush other bdi's to free
+ * memory.
+ */
+ spin_lock_bh(&bdi_lock);
+ list_add_tail(&bdi->bdi_list,
+ &bdi_pending_list);
+ spin_unlock_bh(&bdi_lock);
+
+ wbc.nr_to_write = 1024;
+ generic_sync_bdi_inodes(NULL, &wbc);
+ goto repeat;
+ }
+ }
+
+ finish_wait(&me->wait, &wait);
+ }
+
+ return 0;
+}
+
+/*
+ * Grace period has now ended, init bdi->bdi_list and add us to the
+ * list of bdi's that are pending for task creation. Wake up
+ * bdi_forker_task() to finish the job and add us back to the
+ * active bdi_list.
+ */
+static void bdi_add_to_pending(struct rcu_head *head)
+{
+ struct backing_dev_info *bdi;
+
+ bdi = container_of(head, struct backing_dev_info, rcu_head);
+ INIT_LIST_HEAD(&bdi->bdi_list);
+
+ spin_lock(&bdi_lock);
+ list_add_tail(&bdi->bdi_list, &bdi_pending_list);
+ spin_unlock(&bdi_lock);
+
+ wake_up(&default_backing_dev_info.wait);
+}
+
+void bdi_add_flusher_task(struct backing_dev_info *bdi)
+{
+ if (test_and_set_bit(BDI_pending, &bdi->state))
+ return;
+
+ spin_lock_bh(&bdi_lock);
+ list_del_rcu(&bdi->bdi_list);
+ spin_unlock_bh(&bdi_lock);
+
+ /*
+ * We need to wait for the current grace period to end,
+ * in case others were browsing the bdi_list as well.
+ * So defer the adding and wakeup to after the RCU
+ * grace period has ended.
+ */
+ call_rcu(&bdi->rcu_head, bdi_add_to_pending);
+}
+
int bdi_register(struct backing_dev_info *bdi, struct device *parent,
const char *fmt, ...)
{
@@ -213,9 +357,23 @@ int bdi_register(struct backing_dev_info *bdi, struct device *parent,
goto exit;
}
- spin_lock(&bdi_lock);
- list_add_tail_rcu(&bdi->bdi_list, &bdi_list);
- spin_unlock(&bdi_lock);
+ /*
+ * 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->capabilities & BDI_CAP_FLUSH_FORKER) {
+ bdi->task = kthread_run(bdi_forker_task, bdi, "bdi-%s",
+ dev_name(dev));
+ if (!bdi->task) {
+ ret = -ENOMEM;
+ goto exit;
+ }
+ } else {
+ spin_lock_bh(&bdi_lock);
+ list_add_tail_rcu(&bdi->bdi_list, &bdi_list);
+ spin_unlock_bh(&bdi_lock);
+ }
bdi->dev = dev;
bdi_debug_register(bdi, dev_name(dev));
@@ -231,11 +389,22 @@ int bdi_register_dev(struct backing_dev_info *bdi, dev_t dev)
}
EXPORT_SYMBOL(bdi_register_dev);
+static int sched_wait(void *word)
+{
+ schedule();
+ return 0;
+}
+
static void bdi_remove_from_list(struct backing_dev_info *bdi)
{
- spin_lock(&bdi_lock);
+ /*
+ * If setup is pending, wait for that to complete first
+ */
+ wait_on_bit(&bdi->state, BDI_pending, sched_wait, TASK_UNINTERRUPTIBLE);
+
+ spin_lock_bh(&bdi_lock);
list_del_rcu(&bdi->bdi_list);
- spin_unlock(&bdi_lock);
+ spin_unlock_bh(&bdi_lock);
/*
* In case the bdi is freed right after unregister, we need to
@@ -247,7 +416,13 @@ static void bdi_remove_from_list(struct backing_dev_info *bdi)
void bdi_unregister(struct backing_dev_info *bdi)
{
if (bdi->dev) {
- bdi_remove_from_list(bdi);
+ if (!(bdi->capabilities & BDI_CAP_FLUSH_FORKER)) {
+ bdi_remove_from_list(bdi);
+ if (bdi->task) {
+ kthread_stop(bdi->task);
+ bdi->task = NULL;
+ }
+ }
bdi_debug_unregister(bdi);
device_unregister(bdi->dev);
bdi->dev = NULL;
@@ -257,14 +432,15 @@ EXPORT_SYMBOL(bdi_unregister);
int bdi_init(struct backing_dev_info *bdi)
{
- int i;
- int err;
+ int i, err;
+ INIT_RCU_HEAD(&bdi->rcu_head);
bdi->dev = NULL;
bdi->min_ratio = 0;
bdi->max_ratio = 100;
bdi->max_prop_frac = PROP_FRAC_BASE;
+ init_waitqueue_head(&bdi->wait);
INIT_LIST_HEAD(&bdi->bdi_list);
INIT_LIST_HEAD(&bdi->b_io);
INIT_LIST_HEAD(&bdi->b_dirty);
diff --git a/mm/page-writeback.c b/mm/page-writeback.c
index 3ec11d8..9d37be6 100644
--- a/mm/page-writeback.c
+++ b/mm/page-writeback.c
@@ -36,15 +36,6 @@
#include <linux/pagevec.h>
/*
- * 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.
*
@@ -541,7 +530,7 @@ static void balance_dirty_pages(struct address_space *mapping)
* been flushed to permanent storage.
*/
if (bdi_nr_reclaimable) {
- writeback_inodes(&wbc);
+ generic_sync_bdi_inodes(NULL, &wbc);
pages_written += write_chunk - wbc.nr_to_write;
get_dirty_limits(&background_thresh, &dirty_thresh,
&bdi_thresh, bdi);
@@ -592,7 +581,7 @@ static void balance_dirty_pages(struct address_space *mapping)
(!laptop_mode && (global_page_state(NR_FILE_DIRTY)
+ global_page_state(NR_UNSTABLE_NFS)
> background_thresh)))
- pdflush_operation(background_writeout, 0);
+ bdi_start_writeback(bdi, NULL, 0);
}
void set_page_dirty_balance(struct page *page, int page_mkwrite)
@@ -677,151 +666,36 @@ 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(WRITE, 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)
+int wakeup_flusher_threads(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);
+ bdi_writeback_all(NULL, nr_pages);
+ return 0;
}
-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 - dirty_expire_interval;
- start_jif = jiffies;
- next_jif = start_jif + dirty_writeback_interval;
- 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(WRITE, 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
*/
int dirty_writeback_centisecs_handler(ctl_table *table, int write,
struct file *file, void __user *buffer, size_t *length, loff_t *ppos)
{
proc_dointvec_userhz_jiffies(table, write, file, buffer, length, ppos);
- if (dirty_writeback_interval)
- mod_timer(&wb_timer, jiffies + dirty_writeback_interval);
- 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)
-{
- sys_sync();
-}
-
static void laptop_timer_fn(unsigned long unused)
{
- pdflush_operation(laptop_flush, 0);
+ wakeup_flusher_threads(0);
}
/*
@@ -904,7 +778,6 @@ void __init page_writeback_init(void)
{
int shift;
- mod_timer(&wb_timer, jiffies + dirty_writeback_interval);
writeback_set_ratelimit();
register_cpu_notifier(&ratelimit_nb);
diff --git a/mm/vmscan.c b/mm/vmscan.c
index 56ddf41..8d95d62 100644
--- a/mm/vmscan.c
+++ b/mm/vmscan.c
@@ -1649,7 +1649,7 @@ 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;
}
--
1.6.2.12.g83676
^ permalink raw reply related [flat|nested] 16+ messages in thread* Re: [PATCH 05/12] writeback: switch to per-bdi threads for flushing data
2009-03-22 19:25 ` [PATCH 05/12] writeback: switch to per-bdi threads for flushing data Jens Axboe
@ 2009-03-31 14:11 ` Jan Kara
2009-03-31 16:50 ` Jens Axboe
0 siblings, 1 reply; 16+ messages in thread
From: Jan Kara @ 2009-03-31 14:11 UTC (permalink / raw)
To: Jens Axboe
Cc: linux-kernel, linux-fsdevel, chris.mason, david, npiggin, hch,
akpm
> This gets rid of pdflush for bdi writeout and kupdated style cleaning.
> This is an experiment to see if we get better writeout behaviour with
> per-bdi flushing. Some initial tests look pretty encouraging. 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
>
> So apart from seemingly behaving better for buffered writeout, this also
> allows us to potentially have more than one bdi thread flushing out data.
> This may be useful for NUMA type setups.
>
> A 10 disk test with btrfs performs 26% faster with per-bdi flushing. Other
> tests pending.
>
> Signed-off-by: Jens Axboe <jens.axboe@oracle.com>
Two comments below...
<snip>
> diff --git a/fs/fs-writeback.c b/fs/fs-writeback.c
> index 45d2739..21de5ac 100644
> --- a/fs/fs-writeback.c
> +++ b/fs/fs-writeback.c
> @@ -19,6 +19,8 @@
> #include <linux/sched.h>
> #include <linux/fs.h>
> #include <linux/mm.h>
> +#include <linux/kthread.h>
> +#include <linux/freezer.h>
> #include <linux/writeback.h>
> #include <linux/blkdev.h>
> #include <linux/backing-dev.h>
> @@ -61,10 +63,180 @@ int writeback_in_progress(struct backing_dev_info *bdi)
> */
> static void writeback_release(struct backing_dev_info *bdi)
> {
> - BUG_ON(!writeback_in_progress(bdi));
> + WARN_ON_ONCE(!writeback_in_progress(bdi));
> + bdi->wb_arg.nr_pages = 0;
> + bdi->wb_arg.sb = NULL;
> clear_bit(BDI_pdflush, &bdi->state);
> }
>
> +int bdi_start_writeback(struct backing_dev_info *bdi, struct super_block *sb,
> + long nr_pages)
> +{
> + /*
> + * This only happens the first time someone kicks this bdi, so put
> + * it out-of-line.
> + */
> + if (unlikely(!bdi->task)) {
> + bdi_add_flusher_task(bdi);
> + return 1;
> + }
> +
> + if (writeback_acquire(bdi)) {
> + bdi->wb_arg.nr_pages = nr_pages;
> + bdi->wb_arg.sb = sb;
> + /*
> + * make above store seen before the task is woken
> + */
> + smp_mb();
> + wake_up(&bdi->wait);
> + }
> +
> + return 0;
> +}
> +
> +/*
> + * 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
> +
> +/*
> + * 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 bdi_kupdated(struct backing_dev_info *bdi)
> +{
> + long nr_to_write;
> + struct writeback_control wbc = {
> + .bdi = bdi,
> + .sync_mode = WB_SYNC_NONE,
> + .nr_to_write = 0,
> + .for_kupdate = 1,
> + .range_cyclic = 1,
> + };
> +
> + sync_supers();
> +
> + 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;
> + generic_sync_bdi_inodes(NULL, &wbc);
> + if (wbc.nr_to_write > 0)
> + break; /* All the old data is written */
> + nr_to_write -= MAX_WRITEBACK_PAGES;
> + }
> +}
> +
> +static void bdi_pdflush(struct backing_dev_info *bdi)
> +{
> + struct writeback_control wbc = {
> + .bdi = bdi,
> + .sync_mode = WB_SYNC_NONE,
> + .older_than_this = NULL,
> + .range_cyclic = 1,
> + };
> + long nr_pages = bdi->wb_arg.nr_pages;
> +
> + for (;;) {
> + unsigned long background_thresh, 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) &&
> + nr_pages <= 0)
> + break;
> +
> + wbc.more_io = 0;
> + wbc.encountered_congestion = 0;
> + wbc.nr_to_write = MAX_WRITEBACK_PAGES;
> + wbc.pages_skipped = 0;
> + generic_sync_bdi_inodes(bdi->wb_arg.sb, &wbc);
> + nr_pages -= 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)
> + continue;
> + break;
> + }
> + }
> +}
> +
> +/*
> + * 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 backing_dev_info *bdi)
> +{
> + while (!kthread_should_stop()) {
> + DEFINE_WAIT(wait);
> +
> + prepare_to_wait(&bdi->wait, &wait, TASK_INTERRUPTIBLE);
> + schedule_timeout(dirty_writeback_interval);
> + try_to_freeze();
> +
> + /*
> + * We get here in two cases:
> + *
> + * schedule_timeout() returned because the dirty writeback
> + * interval has elapsed. If that happens, we will be able
> + * to acquire the writeback lock and will proceed to do
> + * kupdated style writeout.
> + *
> + * Someone called bdi_start_writeback(), which will acquire
> + * the writeback lock. This means our writeback_acquire()
> + * below will fail and we call into bdi_pdflush() for
> + * pdflush style writeout.
> + *
> + */
> + if (writeback_acquire(bdi))
> + bdi_kupdated(bdi);
> + else
> + bdi_pdflush(bdi);
> +
> + writeback_release(bdi);
> + finish_wait(&bdi->wait, &wait);
> + }
> +
> + return 0;
> +}
> +
> +void bdi_writeback_all(struct super_block *sb, long nr_pages)
> +{
> + struct backing_dev_info *bdi;
> +
> + rcu_read_lock();
> +
> +restart:
> + list_for_each_entry_rcu(bdi, &bdi_list, bdi_list) {
> + if (!bdi_has_dirty_io(bdi))
> + continue;
> + if (bdi_start_writeback(bdi, sb, nr_pages))
> + goto restart;
> + }
> +
> + rcu_read_unlock();
> +}
> +
> /**
> * __mark_inode_dirty - internal function
> * @inode: inode to mark
> @@ -248,46 +420,6 @@ static void queue_io(struct backing_dev_info *bdi,
> 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)
> -{
> - 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)
> -{
> - 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
> - */
> - rcu_read_lock();
> - list_for_each_entry_rcu(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;
> - }
> - }
> - rcu_read_unlock();
> -
> - return ret;
> -}
> -EXPORT_SYMBOL(sb_has_dirty_inodes);
> -
> /*
> * Write a single inode's dirty pages and inode data out to disk.
> * If `wait' is set, wait on the writeout.
> @@ -446,10 +578,11 @@ __writeback_single_inode(struct inode *inode, struct writeback_control *wbc)
> return __sync_single_inode(inode, wbc);
> }
>
> -static void generic_sync_bdi_inodes(struct backing_dev_info *bdi,
> - struct writeback_control *wbc,
> - int is_blkdev)
> +void generic_sync_bdi_inodes(struct super_block *sb,
> + struct writeback_control *wbc)
> {
> + const int is_blkdev_sb = sb_is_blkdev_sb(sb);
> + struct backing_dev_info *bdi = wbc->bdi;
> const unsigned long start = jiffies; /* livelock avoidance */
>
> spin_lock(&inode_lock);
> @@ -461,9 +594,17 @@ static void generic_sync_bdi_inodes(struct backing_dev_info *bdi,
> struct inode, i_list);
> 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 (is_blkdev) {
> + if (is_blkdev_sb) {
> /*
> * Dirty memory-backed blockdev: the ramdisk
> * driver does this. Skip just this inode
> @@ -485,33 +626,20 @@ static void generic_sync_bdi_inodes(struct backing_dev_info *bdi,
>
> if (wbc->nonblocking && bdi_write_congested(bdi)) {
> wbc->encountered_congestion = 1;
> - if (!is_blkdev)
> + if (!is_blkdev_sb)
> break; /* Skip a congested fs */
> requeue_io(inode);
> continue; /* Skip a congested blockdev */
> }
>
> - if (wbc->bdi && bdi != wbc->bdi) {
> - if (!is_blkdev)
> - break; /* fs has the wrong queue */
> - requeue_io(inode);
> - continue; /* blockdev has wrong queue */
> - }
> -
> /* Was this inode dirtied after sync_sb_inodes was called? */
> if (time_after(inode->dirtied_when, start))
> break;
>
> - /* Is another pdflush already flushing this queue? */
> - if (current_is_pdflush() && !writeback_acquire(bdi))
> - break;
> -
> BUG_ON(inode->i_state & I_FREEING);
> __iget(inode);
> pages_skipped = wbc->pages_skipped;
> __writeback_single_inode(inode, wbc);
> - if (current_is_pdflush())
> - writeback_release(bdi);
> if (wbc->pages_skipped != pages_skipped) {
> /*
> * writeback is not making progress due to locked
> @@ -550,11 +678,6 @@ static void generic_sync_bdi_inodes(struct backing_dev_info *bdi,
> * 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
> @@ -563,13 +686,10 @@ static void generic_sync_bdi_inodes(struct backing_dev_info *bdi,
> void generic_sync_sb_inodes(struct super_block *sb,
> struct writeback_control *wbc)
> {
> - const int is_blkdev = sb_is_blkdev_sb(sb);
> - struct backing_dev_info *bdi;
> -
> - rcu_read_lock();
> - list_for_each_entry_rcu(bdi, &bdi_list, bdi_list)
> - generic_sync_bdi_inodes(bdi, wbc, is_blkdev);
> - rcu_read_unlock();
> + if (wbc->bdi)
> + bdi_start_writeback(wbc->bdi, sb, 0);
> + else
> + bdi_writeback_all(sb, 0);
Hmm, generic_sync_sb_inodes() is also used for calls like sys_sync()
(i.e. data integrity sync). But bdi_start_writeback() (called also from
bdi_writeback_all()) just skips the bdi if somebody is already writing
it. But to ensure data integrity we have to wait for previous writer to
finish (or interupt him somehow) and write it ourselves. Nasty for
performance but needed for integrity...
> if (wbc->sync_mode == WB_SYNC_ALL) {
> struct inode *inode, *old_inode = NULL;
> @@ -624,58 +744,6 @@ static void sync_sb_inodes(struct super_block *sb,
> }
>
> /*
> - * Start writeback of dirty pagecache data against all unlocked inodes.
> - *
> - * 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.
> - *
> - * If `older_than_this' is non-zero then only flush inodes which have a
> - * flushtime older than *older_than_this.
> - *
> - * 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...
> - */
> -void
> -writeback_inodes(struct writeback_control *wbc)
> -{
> - struct super_block *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)
> - sync_sb_inodes(sb, wbc);
> - up_read(&sb->s_umount);
> - }
> - spin_lock(&sb_lock);
> - if (__put_super_and_need_restart(sb))
> - goto restart;
> - }
> - if (wbc->nr_to_write <= 0)
> - break;
> - }
> - spin_unlock(&sb_lock);
> -}
> -
> -/*
> * writeback and wait upon the filesystem's dirty inodes. The caller will
> * do this in two passes - one to write, and one to wait.
> *
> diff --git a/fs/ntfs/super.c b/fs/ntfs/super.c
> index 4a46743..ffa4853 100644
> --- a/fs/ntfs/super.c
> +++ b/fs/ntfs/super.c
> @@ -2373,39 +2373,13 @@ static void ntfs_put_super(struct super_block *sb)
> vol->mftmirr_ino = NULL;
> }
> /*
> - * If any dirty inodes are left, throw away all mft data page cache
> - * pages to allow a clean umount. This should never happen any more
> - * due to mft.c::ntfs_mft_writepage() cleaning all the dirty pages as
> - * the underlying mft records are written out and cleaned. If it does,
> + * We should have no dirty inodes left, due to
> + * mft.c::ntfs_mft_writepage() cleaning all the dirty pages as
> + * the underlying mft records are written out and cleaned.
> * happen anyway, we want to know...
Obviously you've left one line here ;).
> */
> ntfs_commit_inode(vol->mft_ino);
> write_inode_now(vol->mft_ino, 1);
> - if (sb_has_dirty_inodes(sb)) {
> - const char *s1, *s2;
> -
> - mutex_lock(&vol->mft_ino->i_mutex);
> - truncate_inode_pages(vol->mft_ino->i_mapping, 0);
> - mutex_unlock(&vol->mft_ino->i_mutex);
> - write_inode_now(vol->mft_ino, 1);
> - if (sb_has_dirty_inodes(sb)) {
> - static const char *_s1 = "inodes";
> - static const char *_s2 = "";
> - s1 = _s1;
> - s2 = _s2;
> - } else {
> - static const char *_s1 = "mft pages";
> - static const char *_s2 = "They have been thrown "
> - "away. ";
> - s1 = _s1;
> - s2 = _s2;
> - }
> - ntfs_error(sb, "Dirty %s found at umount time. %sYou should "
> - "run chkdsk. Please email "
> - "linux-ntfs-dev@lists.sourceforge.net and say "
> - "that you saw this message. Thank you.", s1,
> - s2);
> - }
> #endif /* NTFS_RW */
>
> iput(vol->mft_ino);
<snip>
Honza
--
Jan Kara <jack@suse.cz>
SuSE CR Labs
^ permalink raw reply [flat|nested] 16+ messages in thread* Re: [PATCH 05/12] writeback: switch to per-bdi threads for flushing data
2009-03-31 14:11 ` Jan Kara
@ 2009-03-31 16:50 ` Jens Axboe
2009-04-01 9:12 ` Jan Kara
0 siblings, 1 reply; 16+ messages in thread
From: Jens Axboe @ 2009-03-31 16:50 UTC (permalink / raw)
To: Jan Kara
Cc: linux-kernel, linux-fsdevel, chris.mason, david, npiggin, hch,
akpm
On Tue, Mar 31 2009, Jan Kara wrote:
> > This gets rid of pdflush for bdi writeout and kupdated style cleaning.
> > This is an experiment to see if we get better writeout behaviour with
> > per-bdi flushing. Some initial tests look pretty encouraging. 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
> >
> > So apart from seemingly behaving better for buffered writeout, this also
> > allows us to potentially have more than one bdi thread flushing out data.
> > This may be useful for NUMA type setups.
> >
> > A 10 disk test with btrfs performs 26% faster with per-bdi flushing. Other
> > tests pending.
> >
> > Signed-off-by: Jens Axboe <jens.axboe@oracle.com>
> Two comments below...
>
> <snip>
> > diff --git a/fs/fs-writeback.c b/fs/fs-writeback.c
> > index 45d2739..21de5ac 100644
> > --- a/fs/fs-writeback.c
> > +++ b/fs/fs-writeback.c
> > @@ -19,6 +19,8 @@
> > #include <linux/sched.h>
> > #include <linux/fs.h>
> > #include <linux/mm.h>
> > +#include <linux/kthread.h>
> > +#include <linux/freezer.h>
> > #include <linux/writeback.h>
> > #include <linux/blkdev.h>
> > #include <linux/backing-dev.h>
> > @@ -61,10 +63,180 @@ int writeback_in_progress(struct backing_dev_info *bdi)
> > */
> > static void writeback_release(struct backing_dev_info *bdi)
> > {
> > - BUG_ON(!writeback_in_progress(bdi));
> > + WARN_ON_ONCE(!writeback_in_progress(bdi));
> > + bdi->wb_arg.nr_pages = 0;
> > + bdi->wb_arg.sb = NULL;
> > clear_bit(BDI_pdflush, &bdi->state);
> > }
> >
> > +int bdi_start_writeback(struct backing_dev_info *bdi, struct super_block *sb,
> > + long nr_pages)
> > +{
> > + /*
> > + * This only happens the first time someone kicks this bdi, so put
> > + * it out-of-line.
> > + */
> > + if (unlikely(!bdi->task)) {
> > + bdi_add_flusher_task(bdi);
> > + return 1;
> > + }
> > +
> > + if (writeback_acquire(bdi)) {
> > + bdi->wb_arg.nr_pages = nr_pages;
> > + bdi->wb_arg.sb = sb;
> > + /*
> > + * make above store seen before the task is woken
> > + */
> > + smp_mb();
> > + wake_up(&bdi->wait);
> > + }
> > +
> > + return 0;
> > +}
> > +
> > +/*
> > + * 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
> > +
> > +/*
> > + * 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 bdi_kupdated(struct backing_dev_info *bdi)
> > +{
> > + long nr_to_write;
> > + struct writeback_control wbc = {
> > + .bdi = bdi,
> > + .sync_mode = WB_SYNC_NONE,
> > + .nr_to_write = 0,
> > + .for_kupdate = 1,
> > + .range_cyclic = 1,
> > + };
> > +
> > + sync_supers();
> > +
> > + 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;
> > + generic_sync_bdi_inodes(NULL, &wbc);
> > + if (wbc.nr_to_write > 0)
> > + break; /* All the old data is written */
> > + nr_to_write -= MAX_WRITEBACK_PAGES;
> > + }
> > +}
> > +
> > +static void bdi_pdflush(struct backing_dev_info *bdi)
> > +{
> > + struct writeback_control wbc = {
> > + .bdi = bdi,
> > + .sync_mode = WB_SYNC_NONE,
> > + .older_than_this = NULL,
> > + .range_cyclic = 1,
> > + };
> > + long nr_pages = bdi->wb_arg.nr_pages;
> > +
> > + for (;;) {
> > + unsigned long background_thresh, 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) &&
> > + nr_pages <= 0)
> > + break;
> > +
> > + wbc.more_io = 0;
> > + wbc.encountered_congestion = 0;
> > + wbc.nr_to_write = MAX_WRITEBACK_PAGES;
> > + wbc.pages_skipped = 0;
> > + generic_sync_bdi_inodes(bdi->wb_arg.sb, &wbc);
> > + nr_pages -= 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)
> > + continue;
> > + break;
> > + }
> > + }
> > +}
> > +
> > +/*
> > + * 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 backing_dev_info *bdi)
> > +{
> > + while (!kthread_should_stop()) {
> > + DEFINE_WAIT(wait);
> > +
> > + prepare_to_wait(&bdi->wait, &wait, TASK_INTERRUPTIBLE);
> > + schedule_timeout(dirty_writeback_interval);
> > + try_to_freeze();
> > +
> > + /*
> > + * We get here in two cases:
> > + *
> > + * schedule_timeout() returned because the dirty writeback
> > + * interval has elapsed. If that happens, we will be able
> > + * to acquire the writeback lock and will proceed to do
> > + * kupdated style writeout.
> > + *
> > + * Someone called bdi_start_writeback(), which will acquire
> > + * the writeback lock. This means our writeback_acquire()
> > + * below will fail and we call into bdi_pdflush() for
> > + * pdflush style writeout.
> > + *
> > + */
> > + if (writeback_acquire(bdi))
> > + bdi_kupdated(bdi);
> > + else
> > + bdi_pdflush(bdi);
> > +
> > + writeback_release(bdi);
> > + finish_wait(&bdi->wait, &wait);
> > + }
> > +
> > + return 0;
> > +}
> > +
> > +void bdi_writeback_all(struct super_block *sb, long nr_pages)
> > +{
> > + struct backing_dev_info *bdi;
> > +
> > + rcu_read_lock();
> > +
> > +restart:
> > + list_for_each_entry_rcu(bdi, &bdi_list, bdi_list) {
> > + if (!bdi_has_dirty_io(bdi))
> > + continue;
> > + if (bdi_start_writeback(bdi, sb, nr_pages))
> > + goto restart;
> > + }
> > +
> > + rcu_read_unlock();
> > +}
> > +
> > /**
> > * __mark_inode_dirty - internal function
> > * @inode: inode to mark
> > @@ -248,46 +420,6 @@ static void queue_io(struct backing_dev_info *bdi,
> > 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)
> > -{
> > - 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)
> > -{
> > - 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
> > - */
> > - rcu_read_lock();
> > - list_for_each_entry_rcu(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;
> > - }
> > - }
> > - rcu_read_unlock();
> > -
> > - return ret;
> > -}
> > -EXPORT_SYMBOL(sb_has_dirty_inodes);
> > -
> > /*
> > * Write a single inode's dirty pages and inode data out to disk.
> > * If `wait' is set, wait on the writeout.
> > @@ -446,10 +578,11 @@ __writeback_single_inode(struct inode *inode, struct writeback_control *wbc)
> > return __sync_single_inode(inode, wbc);
> > }
> >
> > -static void generic_sync_bdi_inodes(struct backing_dev_info *bdi,
> > - struct writeback_control *wbc,
> > - int is_blkdev)
> > +void generic_sync_bdi_inodes(struct super_block *sb,
> > + struct writeback_control *wbc)
> > {
> > + const int is_blkdev_sb = sb_is_blkdev_sb(sb);
> > + struct backing_dev_info *bdi = wbc->bdi;
> > const unsigned long start = jiffies; /* livelock avoidance */
> >
> > spin_lock(&inode_lock);
> > @@ -461,9 +594,17 @@ static void generic_sync_bdi_inodes(struct backing_dev_info *bdi,
> > struct inode, i_list);
> > 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 (is_blkdev) {
> > + if (is_blkdev_sb) {
> > /*
> > * Dirty memory-backed blockdev: the ramdisk
> > * driver does this. Skip just this inode
> > @@ -485,33 +626,20 @@ static void generic_sync_bdi_inodes(struct backing_dev_info *bdi,
> >
> > if (wbc->nonblocking && bdi_write_congested(bdi)) {
> > wbc->encountered_congestion = 1;
> > - if (!is_blkdev)
> > + if (!is_blkdev_sb)
> > break; /* Skip a congested fs */
> > requeue_io(inode);
> > continue; /* Skip a congested blockdev */
> > }
> >
> > - if (wbc->bdi && bdi != wbc->bdi) {
> > - if (!is_blkdev)
> > - break; /* fs has the wrong queue */
> > - requeue_io(inode);
> > - continue; /* blockdev has wrong queue */
> > - }
> > -
> > /* Was this inode dirtied after sync_sb_inodes was called? */
> > if (time_after(inode->dirtied_when, start))
> > break;
> >
> > - /* Is another pdflush already flushing this queue? */
> > - if (current_is_pdflush() && !writeback_acquire(bdi))
> > - break;
> > -
> > BUG_ON(inode->i_state & I_FREEING);
> > __iget(inode);
> > pages_skipped = wbc->pages_skipped;
> > __writeback_single_inode(inode, wbc);
> > - if (current_is_pdflush())
> > - writeback_release(bdi);
> > if (wbc->pages_skipped != pages_skipped) {
> > /*
> > * writeback is not making progress due to locked
> > @@ -550,11 +678,6 @@ static void generic_sync_bdi_inodes(struct backing_dev_info *bdi,
> > * 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
> > @@ -563,13 +686,10 @@ static void generic_sync_bdi_inodes(struct backing_dev_info *bdi,
> > void generic_sync_sb_inodes(struct super_block *sb,
> > struct writeback_control *wbc)
> > {
> > - const int is_blkdev = sb_is_blkdev_sb(sb);
> > - struct backing_dev_info *bdi;
> > -
> > - rcu_read_lock();
> > - list_for_each_entry_rcu(bdi, &bdi_list, bdi_list)
> > - generic_sync_bdi_inodes(bdi, wbc, is_blkdev);
> > - rcu_read_unlock();
> > + if (wbc->bdi)
> > + bdi_start_writeback(wbc->bdi, sb, 0);
> > + else
> > + bdi_writeback_all(sb, 0);
> Hmm, generic_sync_sb_inodes() is also used for calls like sys_sync()
> (i.e. data integrity sync). But bdi_start_writeback() (called also from
> bdi_writeback_all()) just skips the bdi if somebody is already writing
> it. But to ensure data integrity we have to wait for previous writer to
> finish (or interupt him somehow) and write it ourselves. Nasty for
> performance but needed for integrity...
Good point, thanks for your reviews Jan! It may indeed be a problem, if
the new caller is less retrictive than the one currently running. I
guess it's pretty easily fixable by doing a blocking wait on the
writeback bit for those cases, usable from
bdi_start_writeback_blocking() or something to that effect. I'll add
that for v3, it is going to be posted fairly soon.
> > /*
> > - * If any dirty inodes are left, throw away all mft data page cache
> > - * pages to allow a clean umount. This should never happen any more
> > - * due to mft.c::ntfs_mft_writepage() cleaning all the dirty pages as
> > - * the underlying mft records are written out and cleaned. If it does,
> > + * We should have no dirty inodes left, due to
> > + * mft.c::ntfs_mft_writepage() cleaning all the dirty pages as
> > + * the underlying mft records are written out and cleaned.
> > * happen anyway, we want to know...
> Obviously you've left one line here ;).
Oops indeed, thanks!
--
Jens Axboe
^ permalink raw reply [flat|nested] 16+ messages in thread* Re: [PATCH 05/12] writeback: switch to per-bdi threads for flushing data
2009-03-31 16:50 ` Jens Axboe
@ 2009-04-01 9:12 ` Jan Kara
0 siblings, 0 replies; 16+ messages in thread
From: Jan Kara @ 2009-04-01 9:12 UTC (permalink / raw)
To: Jens Axboe
Cc: linux-kernel, linux-fsdevel, chris.mason, david, npiggin, hch,
akpm
On Tue 31-03-09 18:50:40, Jens Axboe wrote:
> On Tue, Mar 31 2009, Jan Kara wrote:
> > > This gets rid of pdflush for bdi writeout and kupdated style cleaning.
> > > This is an experiment to see if we get better writeout behaviour with
> > > per-bdi flushing. Some initial tests look pretty encouraging. 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
> > >
> > > So apart from seemingly behaving better for buffered writeout, this also
> > > allows us to potentially have more than one bdi thread flushing out data.
> > > This may be useful for NUMA type setups.
> > >
> > > A 10 disk test with btrfs performs 26% faster with per-bdi flushing. Other
> > > tests pending.
> > >
> > > Signed-off-by: Jens Axboe <jens.axboe@oracle.com>
> > Two comments below...
> >
> > <snip>
> > > diff --git a/fs/fs-writeback.c b/fs/fs-writeback.c
> > > index 45d2739..21de5ac 100644
> > > --- a/fs/fs-writeback.c
> > > +++ b/fs/fs-writeback.c
> > > @@ -19,6 +19,8 @@
> > > #include <linux/sched.h>
> > > #include <linux/fs.h>
> > > #include <linux/mm.h>
> > > +#include <linux/kthread.h>
> > > +#include <linux/freezer.h>
> > > #include <linux/writeback.h>
> > > #include <linux/blkdev.h>
> > > #include <linux/backing-dev.h>
> > > @@ -61,10 +63,180 @@ int writeback_in_progress(struct backing_dev_info *bdi)
> > > */
> > > static void writeback_release(struct backing_dev_info *bdi)
> > > {
> > > - BUG_ON(!writeback_in_progress(bdi));
> > > + WARN_ON_ONCE(!writeback_in_progress(bdi));
> > > + bdi->wb_arg.nr_pages = 0;
> > > + bdi->wb_arg.sb = NULL;
> > > clear_bit(BDI_pdflush, &bdi->state);
> > > }
> > >
> > > +int bdi_start_writeback(struct backing_dev_info *bdi, struct super_block *sb,
> > > + long nr_pages)
> > > +{
> > > + /*
> > > + * This only happens the first time someone kicks this bdi, so put
> > > + * it out-of-line.
> > > + */
> > > + if (unlikely(!bdi->task)) {
> > > + bdi_add_flusher_task(bdi);
> > > + return 1;
> > > + }
> > > +
> > > + if (writeback_acquire(bdi)) {
> > > + bdi->wb_arg.nr_pages = nr_pages;
> > > + bdi->wb_arg.sb = sb;
> > > + /*
> > > + * make above store seen before the task is woken
> > > + */
> > > + smp_mb();
> > > + wake_up(&bdi->wait);
> > > + }
> > > +
> > > + return 0;
> > > +}
> > > +
> > > +/*
> > > + * 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
> > > +
> > > +/*
> > > + * 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 bdi_kupdated(struct backing_dev_info *bdi)
> > > +{
> > > + long nr_to_write;
> > > + struct writeback_control wbc = {
> > > + .bdi = bdi,
> > > + .sync_mode = WB_SYNC_NONE,
> > > + .nr_to_write = 0,
> > > + .for_kupdate = 1,
> > > + .range_cyclic = 1,
> > > + };
> > > +
> > > + sync_supers();
> > > +
> > > + 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;
> > > + generic_sync_bdi_inodes(NULL, &wbc);
> > > + if (wbc.nr_to_write > 0)
> > > + break; /* All the old data is written */
> > > + nr_to_write -= MAX_WRITEBACK_PAGES;
> > > + }
> > > +}
> > > +
> > > +static void bdi_pdflush(struct backing_dev_info *bdi)
> > > +{
> > > + struct writeback_control wbc = {
> > > + .bdi = bdi,
> > > + .sync_mode = WB_SYNC_NONE,
> > > + .older_than_this = NULL,
> > > + .range_cyclic = 1,
> > > + };
> > > + long nr_pages = bdi->wb_arg.nr_pages;
> > > +
> > > + for (;;) {
> > > + unsigned long background_thresh, 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) &&
> > > + nr_pages <= 0)
> > > + break;
> > > +
> > > + wbc.more_io = 0;
> > > + wbc.encountered_congestion = 0;
> > > + wbc.nr_to_write = MAX_WRITEBACK_PAGES;
> > > + wbc.pages_skipped = 0;
> > > + generic_sync_bdi_inodes(bdi->wb_arg.sb, &wbc);
> > > + nr_pages -= 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)
> > > + continue;
> > > + break;
> > > + }
> > > + }
> > > +}
> > > +
> > > +/*
> > > + * 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 backing_dev_info *bdi)
> > > +{
> > > + while (!kthread_should_stop()) {
> > > + DEFINE_WAIT(wait);
> > > +
> > > + prepare_to_wait(&bdi->wait, &wait, TASK_INTERRUPTIBLE);
> > > + schedule_timeout(dirty_writeback_interval);
> > > + try_to_freeze();
> > > +
> > > + /*
> > > + * We get here in two cases:
> > > + *
> > > + * schedule_timeout() returned because the dirty writeback
> > > + * interval has elapsed. If that happens, we will be able
> > > + * to acquire the writeback lock and will proceed to do
> > > + * kupdated style writeout.
> > > + *
> > > + * Someone called bdi_start_writeback(), which will acquire
> > > + * the writeback lock. This means our writeback_acquire()
> > > + * below will fail and we call into bdi_pdflush() for
> > > + * pdflush style writeout.
> > > + *
> > > + */
> > > + if (writeback_acquire(bdi))
> > > + bdi_kupdated(bdi);
> > > + else
> > > + bdi_pdflush(bdi);
> > > +
> > > + writeback_release(bdi);
> > > + finish_wait(&bdi->wait, &wait);
> > > + }
> > > +
> > > + return 0;
> > > +}
> > > +
> > > +void bdi_writeback_all(struct super_block *sb, long nr_pages)
> > > +{
> > > + struct backing_dev_info *bdi;
> > > +
> > > + rcu_read_lock();
> > > +
> > > +restart:
> > > + list_for_each_entry_rcu(bdi, &bdi_list, bdi_list) {
> > > + if (!bdi_has_dirty_io(bdi))
> > > + continue;
> > > + if (bdi_start_writeback(bdi, sb, nr_pages))
> > > + goto restart;
> > > + }
> > > +
> > > + rcu_read_unlock();
> > > +}
> > > +
> > > /**
> > > * __mark_inode_dirty - internal function
> > > * @inode: inode to mark
> > > @@ -248,46 +420,6 @@ static void queue_io(struct backing_dev_info *bdi,
> > > 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)
> > > -{
> > > - 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)
> > > -{
> > > - 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
> > > - */
> > > - rcu_read_lock();
> > > - list_for_each_entry_rcu(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;
> > > - }
> > > - }
> > > - rcu_read_unlock();
> > > -
> > > - return ret;
> > > -}
> > > -EXPORT_SYMBOL(sb_has_dirty_inodes);
> > > -
> > > /*
> > > * Write a single inode's dirty pages and inode data out to disk.
> > > * If `wait' is set, wait on the writeout.
> > > @@ -446,10 +578,11 @@ __writeback_single_inode(struct inode *inode, struct writeback_control *wbc)
> > > return __sync_single_inode(inode, wbc);
> > > }
> > >
> > > -static void generic_sync_bdi_inodes(struct backing_dev_info *bdi,
> > > - struct writeback_control *wbc,
> > > - int is_blkdev)
> > > +void generic_sync_bdi_inodes(struct super_block *sb,
> > > + struct writeback_control *wbc)
> > > {
> > > + const int is_blkdev_sb = sb_is_blkdev_sb(sb);
> > > + struct backing_dev_info *bdi = wbc->bdi;
> > > const unsigned long start = jiffies; /* livelock avoidance */
> > >
> > > spin_lock(&inode_lock);
> > > @@ -461,9 +594,17 @@ static void generic_sync_bdi_inodes(struct backing_dev_info *bdi,
> > > struct inode, i_list);
> > > 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 (is_blkdev) {
> > > + if (is_blkdev_sb) {
> > > /*
> > > * Dirty memory-backed blockdev: the ramdisk
> > > * driver does this. Skip just this inode
> > > @@ -485,33 +626,20 @@ static void generic_sync_bdi_inodes(struct backing_dev_info *bdi,
> > >
> > > if (wbc->nonblocking && bdi_write_congested(bdi)) {
> > > wbc->encountered_congestion = 1;
> > > - if (!is_blkdev)
> > > + if (!is_blkdev_sb)
> > > break; /* Skip a congested fs */
> > > requeue_io(inode);
> > > continue; /* Skip a congested blockdev */
> > > }
> > >
> > > - if (wbc->bdi && bdi != wbc->bdi) {
> > > - if (!is_blkdev)
> > > - break; /* fs has the wrong queue */
> > > - requeue_io(inode);
> > > - continue; /* blockdev has wrong queue */
> > > - }
> > > -
> > > /* Was this inode dirtied after sync_sb_inodes was called? */
> > > if (time_after(inode->dirtied_when, start))
> > > break;
> > >
> > > - /* Is another pdflush already flushing this queue? */
> > > - if (current_is_pdflush() && !writeback_acquire(bdi))
> > > - break;
> > > -
> > > BUG_ON(inode->i_state & I_FREEING);
> > > __iget(inode);
> > > pages_skipped = wbc->pages_skipped;
> > > __writeback_single_inode(inode, wbc);
> > > - if (current_is_pdflush())
> > > - writeback_release(bdi);
> > > if (wbc->pages_skipped != pages_skipped) {
> > > /*
> > > * writeback is not making progress due to locked
> > > @@ -550,11 +678,6 @@ static void generic_sync_bdi_inodes(struct backing_dev_info *bdi,
> > > * 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
> > > @@ -563,13 +686,10 @@ static void generic_sync_bdi_inodes(struct backing_dev_info *bdi,
> > > void generic_sync_sb_inodes(struct super_block *sb,
> > > struct writeback_control *wbc)
> > > {
> > > - const int is_blkdev = sb_is_blkdev_sb(sb);
> > > - struct backing_dev_info *bdi;
> > > -
> > > - rcu_read_lock();
> > > - list_for_each_entry_rcu(bdi, &bdi_list, bdi_list)
> > > - generic_sync_bdi_inodes(bdi, wbc, is_blkdev);
> > > - rcu_read_unlock();
> > > + if (wbc->bdi)
> > > + bdi_start_writeback(wbc->bdi, sb, 0);
> > > + else
> > > + bdi_writeback_all(sb, 0);
> > Hmm, generic_sync_sb_inodes() is also used for calls like sys_sync()
> > (i.e. data integrity sync). But bdi_start_writeback() (called also from
> > bdi_writeback_all()) just skips the bdi if somebody is already writing
> > it. But to ensure data integrity we have to wait for previous writer to
> > finish (or interupt him somehow) and write it ourselves. Nasty for
> > performance but needed for integrity...
>
> Good point, thanks for your reviews Jan! It may indeed be a problem, if
Welcome.
> the new caller is less retrictive than the one currently running. I
> guess it's pretty easily fixable by doing a blocking wait on the
> writeback bit for those cases, usable from
> bdi_start_writeback_blocking() or something to that effect. I'll add
> that for v3, it is going to be posted fairly soon.
Yes, that should be fine. We do it similarly for I_SYNC bit on inodes -
actually it's there for exactly above reason.
Honza
--
Jan Kara <jack@suse.cz>
SUSE Labs, CR
^ permalink raw reply [flat|nested] 16+ messages in thread
* [PATCH 06/12] writeback get rid of pdflush completely
2009-03-22 19:25 [PATCH 0/12] Per-bdi writeback flusher threads #2 Jens Axboe
` (4 preceding siblings ...)
2009-03-22 19:25 ` [PATCH 05/12] writeback: switch to per-bdi threads for flushing data Jens Axboe
@ 2009-03-22 19:25 ` Jens Axboe
2009-03-22 19:25 ` [PATCH 07/12] writeback: separate the flushing state/task from the bdi Jens Axboe
` (5 subsequent siblings)
11 siblings, 0 replies; 16+ messages in thread
From: Jens Axboe @ 2009-03-22 19:25 UTC (permalink / raw)
To: linux-kernel, linux-fsdevel
Cc: chris.mason, david, npiggin, hch, akpm, Jens Axboe
It is now unused, so kill it off.
Signed-off-by: Jens Axboe <jens.axboe@oracle.com>
---
fs/fs-writeback.c | 5 +
include/linux/writeback.h | 12 --
mm/Makefile | 2 +-
mm/pdflush.c | 251 ---------------------------------------------
4 files changed, 6 insertions(+), 264 deletions(-)
delete mode 100644 mm/pdflush.c
diff --git a/fs/fs-writeback.c b/fs/fs-writeback.c
index 21de5ac..54c5e19 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 = 0;
+
/**
* writeback_acquire - attempt to get exclusive writeback access to a device
* @bdi: the device's backing_dev_info structure
diff --git a/include/linux/writeback.h b/include/linux/writeback.h
index 3697e91..f96fea3 100644
--- a/include/linux/writeback.h
+++ b/include/linux/writeback.h
@@ -14,17 +14,6 @@ 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
*/
enum writeback_sync_modes {
@@ -151,7 +140,6 @@ 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 72255be..6443e19 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 15de509..0000000
--- a/mm/pdflush.c
+++ /dev/null
@@ -1,251 +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 <linux/sched.h>
-#include <linux/list.h>
-#include <linux/signal.h>
-#include <linux/spinlock.h>
-#include <linux/gfp.h>
-#include <linux/init.h>
-#include <linux/module.h>
-#include <linux/fs.h> /* Needed by writeback.h */
-#include <linux/writeback.h> /* Prototypes pdflush_operation() */
-#include <linux/kthread.h>
-#include <linux/cpuset.h>
-#include <linux/freezer.h>
-
-
-/*
- * 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);
- nr_pdflush_threads++;
- 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);
-
- /*
- * Thread creation: For how long have there been zero
- * available threads?
- */
- if (time_after(jiffies, last_empty_jifs + 1 * HZ)) {
- /* unlocked list_empty() test is OK here */
- if (list_empty(&pdflush_list)) {
- /* unlocked test is OK here */
- if (nr_pdflush_threads < MAX_PDFLUSH_THREADS)
- 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_MASK_ALL.
- * 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)
-{
- kthread_run(pdflush, NULL, "pdflush");
-}
-
-static int __init pdflush_init(void)
-{
- int i;
-
- for (i = 0; i < MIN_PDFLUSH_THREADS; i++)
- start_one_pdflush_thread();
- return 0;
-}
-
-module_init(pdflush_init);
--
1.6.2.12.g83676
^ permalink raw reply related [flat|nested] 16+ messages in thread* [PATCH 07/12] writeback: separate the flushing state/task from the bdi
2009-03-22 19:25 [PATCH 0/12] Per-bdi writeback flusher threads #2 Jens Axboe
` (5 preceding siblings ...)
2009-03-22 19:25 ` [PATCH 06/12] writeback get rid of pdflush completely Jens Axboe
@ 2009-03-22 19:25 ` Jens Axboe
2009-03-22 19:26 ` [PATCH 08/12] writeback: support > 1 flusher thread per bdi Jens Axboe
` (4 subsequent siblings)
11 siblings, 0 replies; 16+ messages in thread
From: Jens Axboe @ 2009-03-22 19:25 UTC (permalink / raw)
To: linux-kernel, linux-fsdevel
Cc: chris.mason, david, npiggin, hch, akpm, Jens Axboe
Add a struct bdi_writeback for tracking and handling dirty IO. This
is in preparation for adding > 1 flusher task per bdi.
Signed-off-by: Jens Axboe <jens.axboe@oracle.com>
---
fs/fs-writeback.c | 140 +++++++++++++++++----------
include/linux/backing-dev.h | 42 +++++----
mm/backing-dev.c | 221 ++++++++++++++++++++++++++++--------------
3 files changed, 258 insertions(+), 145 deletions(-)
diff --git a/fs/fs-writeback.c b/fs/fs-writeback.c
index 54c5e19..34ee130 100644
--- a/fs/fs-writeback.c
+++ b/fs/fs-writeback.c
@@ -46,9 +46,11 @@ int nr_pdflush_threads = 0;
* unless they implement their own. Which is somewhat inefficient, as this
* may prevent concurrent writeback against multiple devices.
*/
-static int writeback_acquire(struct backing_dev_info *bdi)
+static int writeback_acquire(struct bdi_writeback *wb)
{
- return !test_and_set_bit(BDI_pdflush, &bdi->state);
+ struct backing_dev_info *bdi = wb->bdi;
+
+ return !test_and_set_bit(wb->nr, &bdi->wb_active);
}
/**
@@ -59,19 +61,38 @@ static int writeback_acquire(struct backing_dev_info *bdi)
*/
int writeback_in_progress(struct backing_dev_info *bdi)
{
- return test_bit(BDI_pdflush, &bdi->state);
+ return bdi->wb_active != 0;
}
/**
* 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 writeback_release(struct bdi_writeback *wb)
{
- WARN_ON_ONCE(!writeback_in_progress(bdi));
- bdi->wb_arg.nr_pages = 0;
- bdi->wb_arg.sb = NULL;
- clear_bit(BDI_pdflush, &bdi->state);
+ struct backing_dev_info *bdi = wb->bdi;
+
+ wb->nr_pages = 0;
+ wb->sb = NULL;
+ clear_bit(wb->nr, &bdi->wb_active);
+}
+
+static void wb_start_writeback(struct bdi_writeback *wb, struct super_block *sb,
+ long nr_pages)
+{
+ if (!wb_has_dirty_io(wb))
+ return;
+
+ if (writeback_acquire(wb)) {
+ wb->nr_pages = nr_pages;
+ wb->sb = sb;
+
+ /*
+ * make above store seen before the task is woken
+ */
+ smp_mb();
+ wake_up(&wb->wait);
+ }
}
int bdi_start_writeback(struct backing_dev_info *bdi, struct super_block *sb,
@@ -81,21 +102,12 @@ int bdi_start_writeback(struct backing_dev_info *bdi, struct super_block *sb,
* This only happens the first time someone kicks this bdi, so put
* it out-of-line.
*/
- if (unlikely(!bdi->task)) {
+ if (unlikely(!bdi->wb.task)) {
bdi_add_flusher_task(bdi);
return 1;
}
- if (writeback_acquire(bdi)) {
- bdi->wb_arg.nr_pages = nr_pages;
- bdi->wb_arg.sb = sb;
- /*
- * make above store seen before the task is woken
- */
- smp_mb();
- wake_up(&bdi->wait);
- }
-
+ wb_start_writeback(&bdi->wb, sb, nr_pages);
return 0;
}
@@ -123,11 +135,11 @@ int bdi_start_writeback(struct backing_dev_info *bdi, struct super_block *sb,
* 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 bdi_kupdated(struct backing_dev_info *bdi)
+static void wb_kupdated(struct bdi_writeback *wb)
{
long nr_to_write;
struct writeback_control wbc = {
- .bdi = bdi,
+ .bdi = wb->bdi,
.sync_mode = WB_SYNC_NONE,
.nr_to_write = 0,
.for_kupdate = 1,
@@ -151,15 +163,19 @@ static void bdi_kupdated(struct backing_dev_info *bdi)
}
}
-static void bdi_pdflush(struct backing_dev_info *bdi)
+static void generic_sync_wb_inodes(struct bdi_writeback *wb,
+ struct super_block *sb,
+ struct writeback_control *wbc);
+
+static void wb_writeback(struct bdi_writeback *wb)
{
struct writeback_control wbc = {
- .bdi = bdi,
+ .bdi = wb->bdi,
.sync_mode = WB_SYNC_NONE,
.older_than_this = NULL,
.range_cyclic = 1,
};
- long nr_pages = bdi->wb_arg.nr_pages;
+ long nr_pages = wb->nr_pages;
for (;;) {
unsigned long background_thresh, dirty_thresh;
@@ -173,7 +189,7 @@ static void bdi_pdflush(struct backing_dev_info *bdi)
wbc.encountered_congestion = 0;
wbc.nr_to_write = MAX_WRITEBACK_PAGES;
wbc.pages_skipped = 0;
- generic_sync_bdi_inodes(bdi->wb_arg.sb, &wbc);
+ generic_sync_wb_inodes(wb, wb->sb, &wbc);
nr_pages -= MAX_WRITEBACK_PAGES - wbc.nr_to_write;
/*
* If we ran out of stuff to write, bail unless more_io got set
@@ -190,12 +206,12 @@ static void bdi_pdflush(struct backing_dev_info *bdi)
* 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 backing_dev_info *bdi)
+int bdi_writeback_task(struct bdi_writeback *wb)
{
while (!kthread_should_stop()) {
DEFINE_WAIT(wait);
- prepare_to_wait(&bdi->wait, &wait, TASK_INTERRUPTIBLE);
+ prepare_to_wait(&wb->wait, &wait, TASK_INTERRUPTIBLE);
schedule_timeout(dirty_writeback_interval);
try_to_freeze();
@@ -213,13 +229,13 @@ int bdi_writeback_task(struct backing_dev_info *bdi)
* pdflush style writeout.
*
*/
- if (writeback_acquire(bdi))
- bdi_kupdated(bdi);
+ if (writeback_acquire(wb))
+ wb_kupdated(wb);
else
- bdi_pdflush(bdi);
+ wb_writeback(wb);
- writeback_release(bdi);
- finish_wait(&bdi->wait, &wait);
+ writeback_release(wb);
+ finish_wait(&wb->wait, &wait);
}
return 0;
@@ -242,6 +258,14 @@ restart:
rcu_read_unlock();
}
+/*
+ * We have only a single wb per bdi, so just return that.
+ */
+static inline struct bdi_writeback *inode_get_wb(struct inode *inode)
+{
+ return &inode_to_bdi(inode)->wb;
+}
+
/**
* __mark_inode_dirty - internal function
* @inode: inode to mark
@@ -340,9 +364,10 @@ void __mark_inode_dirty(struct inode *inode, int flags)
* reposition it (that would break b_dirty time-ordering).
*/
if (!was_dirty) {
+ struct bdi_writeback *wb = inode_get_wb(inode);
+
inode->dirtied_when = jiffies;
- list_move(&inode->i_list,
- &inode_to_bdi(inode)->b_dirty);
+ list_move(&inode->i_list, &wb->b_dirty);
}
}
out:
@@ -369,16 +394,16 @@ 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_get_wb(inode);
- 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_after_eq(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);
}
/*
@@ -386,7 +411,9 @@ 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_get_wb(inode);
+
+ list_move(&inode->i_list, &wb->b_more_io);
}
static void inode_sync_complete(struct inode *inode)
@@ -418,11 +445,10 @@ 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);
}
/*
@@ -583,19 +609,19 @@ __writeback_single_inode(struct inode *inode, struct writeback_control *wbc)
return __sync_single_inode(inode, wbc);
}
-void generic_sync_bdi_inodes(struct super_block *sb,
- struct writeback_control *wbc)
+static void generic_sync_wb_inodes(struct bdi_writeback *wb,
+ struct super_block *sb,
+ struct writeback_control *wbc)
{
const int is_blkdev_sb = sb_is_blkdev_sb(sb);
- struct backing_dev_info *bdi = wbc->bdi;
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;
@@ -607,7 +633,7 @@ void generic_sync_bdi_inodes(struct super_block *sb,
continue;
}
- if (!bdi_cap_writeback_dirty(bdi)) {
+ if (!bdi_cap_writeback_dirty(wb->bdi)) {
redirty_tail(inode);
if (is_blkdev_sb) {
/*
@@ -629,7 +655,7 @@ void generic_sync_bdi_inodes(struct super_block *sb,
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 */
@@ -660,7 +686,7 @@ void generic_sync_bdi_inodes(struct super_block *sb,
wbc->more_io = 1;
break;
}
- if (!list_empty(&bdi->b_more_io))
+ if (!list_empty(&wb->b_more_io))
wbc->more_io = 1;
}
@@ -668,6 +694,14 @@ void generic_sync_bdi_inodes(struct super_block *sb,
/* Leave any unwritten inodes on b_io */
}
+void generic_sync_bdi_inodes(struct super_block *sb,
+ struct writeback_control *wbc)
+{
+ struct backing_dev_info *bdi = wbc->bdi;
+
+ generic_sync_wb_inodes(&bdi->wb, sb, 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.
diff --git a/include/linux/backing-dev.h b/include/linux/backing-dev.h
index b9e2085..e316349 100644
--- a/include/linux/backing-dev.h
+++ b/include/linux/backing-dev.h
@@ -23,8 +23,8 @@ 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_write_congested, /* The write queue is getting full */
BDI_read_congested, /* The read queue is getting full */
BDI_unused, /* Available bits start here */
@@ -40,15 +40,23 @@ enum bdi_stat_item {
#define BDI_STAT_BATCH (8*(1+ilog2(nr_cpu_ids)))
-struct bdi_writeback_arg {
- unsigned long nr_pages;
- struct super_block *sb;
+struct bdi_writeback {
+ struct backing_dev_info *bdi; /* our parent bdi */
+ unsigned int nr;
+
+ struct task_struct *task; /* writeback task */
+ wait_queue_head_t wait;
+ 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 */
+
+ unsigned long nr_pages;
+ struct super_block *sb;
};
struct backing_dev_info {
- struct list_head bdi_list;
struct rcu_head rcu_head;
-
+ 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 */
@@ -65,14 +73,11 @@ 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 */
+ unsigned long wb_active; /* bitmap of active tasks */
+ unsigned long wb_mask; /* number of registered tasks */
- struct task_struct *task; /* writeback task */
- wait_queue_head_t wait;
- struct bdi_writeback_arg wb_arg; /* protected by BDI_pdflush */
- 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 device *dev;
#ifdef CONFIG_DEBUG_FS
struct dentry *debug_dir;
@@ -89,18 +94,19 @@ int bdi_register_dev(struct backing_dev_info *bdi, dev_t dev);
void bdi_unregister(struct backing_dev_info *bdi);
int bdi_start_writeback(struct backing_dev_info *bdi, struct super_block *sb,
long nr_pages);
-int bdi_writeback_task(struct backing_dev_info *bdi);
+int bdi_writeback_task(struct bdi_writeback *wb);
void bdi_writeback_all(struct super_block *sb, long nr_pages);
void bdi_add_flusher_task(struct backing_dev_info *bdi);
+int bdi_has_dirty_io(struct backing_dev_info *bdi);
extern spinlock_t bdi_lock;
extern struct list_head bdi_list;
-static inline int bdi_has_dirty_io(struct backing_dev_info *bdi)
+static inline int wb_has_dirty_io(struct bdi_writeback *wb)
{
- return !list_empty(&bdi->b_dirty) ||
- !list_empty(&bdi->b_io) ||
- !list_empty(&bdi->b_more_io);
+ 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,
diff --git a/mm/backing-dev.c b/mm/backing-dev.c
index b4a74d3..c0cfea0 100644
--- a/mm/backing-dev.c
+++ b/mm/backing-dev.c
@@ -199,17 +199,59 @@ 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;
+ init_waitqueue_head(&wb->wait);
+ INIT_LIST_HEAD(&wb->b_dirty);
+ INIT_LIST_HEAD(&wb->b_io);
+ INIT_LIST_HEAD(&wb->b_more_io);
+}
+
+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,
+ };
+
+ generic_sync_bdi_inodes(NULL, &wbc);
+}
+
+static int wb_assign_nr(struct backing_dev_info *bdi, struct bdi_writeback *wb)
+{
+ set_bit(0, &bdi->wb_mask);
+ wb->nr = 0;
+ return 0;
+}
+
+static void bdi_put_wb(struct backing_dev_info *bdi, struct bdi_writeback *wb)
+{
+ clear_bit(wb->nr, &bdi->wb_mask);
+ clear_bit(BDI_wb_alloc, &bdi->state);
+}
+
+static struct bdi_writeback *bdi_new_wb(struct backing_dev_info *bdi)
+{
+ struct bdi_writeback *wb;
+
+ set_bit(BDI_wb_alloc, &bdi->state);
+ wb = &bdi->wb;
+ wb_assign_nr(bdi, wb);
+ return wb;
+}
+
static int bdi_start_fn(void *ptr)
{
- struct backing_dev_info *bdi = ptr;
+ struct bdi_writeback *wb = ptr;
+ struct backing_dev_info *bdi = wb->bdi;
struct task_struct *tsk = current;
-
- /*
- * Add us to the active bdi_list
- */
- spin_lock_bh(&bdi_lock);
- list_add_rcu(&bdi->bdi_list, &bdi_list);
- spin_unlock_bh(&bdi_lock);
+ int ret;
tsk->flags |= PF_FLUSHER | PF_SWAPWRITE;
set_freezable();
@@ -225,77 +267,81 @@ static int bdi_start_fn(void *ptr)
clear_bit(BDI_pending, &bdi->state);
wake_up_bit(&bdi->state, BDI_pending);
- return bdi_writeback_task(bdi);
+ ret = bdi_writeback_task(wb);
+
+ bdi_put_wb(bdi, wb);
+ return ret;
+}
+
+int bdi_has_dirty_io(struct backing_dev_info *bdi)
+{
+ return wb_has_dirty_io(&bdi->wb);
}
static int bdi_forker_task(void *ptr)
{
- struct backing_dev_info *bdi, *me = ptr;
+ struct bdi_writeback *me = ptr;
for (;;) {
+ struct backing_dev_info *bdi;
+ struct bdi_writeback *wb;
DEFINE_WAIT(wait);
/*
* Should never trigger on the default bdi
*/
- WARN_ON(bdi_has_dirty_io(me));
+ if (wb_has_dirty_io(me)) {
+ bdi_flush_io(me->bdi);
+ WARN_ON(1);
+ }
prepare_to_wait(&me->wait, &wait, TASK_INTERRUPTIBLE);
+
smp_mb();
if (list_empty(&bdi_pending_list))
schedule();
- else {
+
+ finish_wait(&me->wait, &wait);
repeat:
- bdi = NULL;
+ bdi = NULL;
+ spin_lock_bh(&bdi_lock);
+ if (!list_empty(&bdi_pending_list)) {
+ bdi = list_entry(bdi_pending_list.next,
+ struct backing_dev_info, bdi_list);
+ list_del_init(&bdi->bdi_list);
+ }
+ spin_unlock_bh(&bdi_lock);
- spin_lock_bh(&bdi_lock);
- if (!list_empty(&bdi_pending_list)) {
- bdi = list_entry(bdi_pending_list.next,
- struct backing_dev_info,
- bdi_list);
- list_del_init(&bdi->bdi_list);
- }
- spin_unlock_bh(&bdi_lock);
+ if (!bdi)
+ continue;
- /*
- * If no bdi or bdi already got setup, continue
- */
- if (!bdi || bdi->task)
- continue;
+ wb = bdi_new_wb(bdi);
+ if (!wb)
+ goto readd_flush;
- bdi->task = kthread_run(bdi_start_fn, bdi, "bdi-%s",
+ wb->task = kthread_run(bdi_start_fn, wb, "bdi-%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 (!wb->task) {
+ bdi_put_wb(bdi, wb);
+readd_flush:
/*
- * 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.
+ * Add this 'bdi' to the back, so we get
+ * a chance to flush other bdi's to free
+ * memory.
*/
- if (!bdi->task) {
- struct writeback_control wbc = {
- .bdi = bdi,
- .sync_mode = WB_SYNC_NONE,
- .older_than_this = NULL,
- .range_cyclic = 1,
- };
-
- /*
- * Add this 'bdi' to the back, so we get
- * a chance to flush other bdi's to free
- * memory.
- */
- spin_lock_bh(&bdi_lock);
- list_add_tail(&bdi->bdi_list,
- &bdi_pending_list);
- spin_unlock_bh(&bdi_lock);
-
- wbc.nr_to_write = 1024;
- generic_sync_bdi_inodes(NULL, &wbc);
- goto repeat;
- }
- }
+ spin_lock_bh(&bdi_lock);
+ list_add_tail(&bdi->bdi_list, &bdi_pending_list);
+ spin_unlock_bh(&bdi_lock);
- finish_wait(&me->wait, &wait);
+ bdi_flush_io(bdi);
+ goto repeat;
+ }
}
return 0;
@@ -318,11 +364,21 @@ static void bdi_add_to_pending(struct rcu_head *head)
list_add_tail(&bdi->bdi_list, &bdi_pending_list);
spin_unlock(&bdi_lock);
- wake_up(&default_backing_dev_info.wait);
+ wake_up(&default_backing_dev_info.wb.wait);
}
+/*
+ * Add a new flusher task that gets created for any bdi
+ * that has dirty data pending writeout
+ */
void bdi_add_flusher_task(struct backing_dev_info *bdi)
{
+ if (!bdi_cap_writeback_dirty(bdi))
+ return;
+
+ /*
+ * Someone already marked this pending for task creation
+ */
if (test_and_set_bit(BDI_pending, &bdi->state))
return;
@@ -338,6 +394,7 @@ void bdi_add_flusher_task(struct backing_dev_info *bdi)
*/
call_rcu(&bdi->rcu_head, bdi_add_to_pending);
}
+EXPORT_SYMBOL(bdi_add_flusher_task);
int bdi_register(struct backing_dev_info *bdi, struct device *parent,
const char *fmt, ...)
@@ -363,9 +420,18 @@ int bdi_register(struct backing_dev_info *bdi, struct device *parent,
* on-demand when they need it.
*/
if (bdi->capabilities & BDI_CAP_FLUSH_FORKER) {
- bdi->task = kthread_run(bdi_forker_task, bdi, "bdi-%s",
+ struct bdi_writeback *wb;
+
+ wb = bdi_new_wb(bdi);
+ if (!wb) {
+ ret = -ENOMEM;
+ goto exit;
+ }
+
+ wb->task = kthread_run(bdi_forker_task, wb, "bdi-%s",
dev_name(dev));
- if (!bdi->task) {
+ if (!wb->task) {
+ bdi_put_wb(bdi, wb);
ret = -ENOMEM;
goto exit;
}
@@ -395,18 +461,33 @@ static int sched_wait(void *word)
return 0;
}
-static void bdi_remove_from_list(struct backing_dev_info *bdi)
+/*
+ * Remove bdi from global list and shutdown any threads we have running
+ */
+static void bdi_wb_shutdown(struct backing_dev_info *bdi)
{
+ if (!bdi_cap_writeback_dirty(bdi))
+ return;
+
/*
* If setup is pending, wait for that to complete first
+ * Make sure nobody finds us on the bdi_list anymore
*/
wait_on_bit(&bdi->state, BDI_pending, sched_wait, TASK_UNINTERRUPTIBLE);
+ /*
+ * Make sure nobody finds us on the bdi_list anymore
+ */
spin_lock_bh(&bdi_lock);
list_del_rcu(&bdi->bdi_list);
spin_unlock_bh(&bdi_lock);
/*
+ * Tells flusher task to exit
+ */
+ kthread_stop(bdi->wb.task);
+
+ /*
* In case the bdi is freed right after unregister, we need to
* make sure any RCU sections have exited
*/
@@ -416,13 +497,8 @@ static void bdi_remove_from_list(struct backing_dev_info *bdi)
void bdi_unregister(struct backing_dev_info *bdi)
{
if (bdi->dev) {
- if (!(bdi->capabilities & BDI_CAP_FLUSH_FORKER)) {
- bdi_remove_from_list(bdi);
- if (bdi->task) {
- kthread_stop(bdi->task);
- bdi->task = NULL;
- }
- }
+ if (!(bdi->capabilities & BDI_CAP_FLUSH_FORKER))
+ bdi_wb_shutdown(bdi);
bdi_debug_unregister(bdi);
device_unregister(bdi->dev);
bdi->dev = NULL;
@@ -440,11 +516,10 @@ int bdi_init(struct backing_dev_info *bdi)
bdi->min_ratio = 0;
bdi->max_ratio = 100;
bdi->max_prop_frac = PROP_FRAC_BASE;
- init_waitqueue_head(&bdi->wait);
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);
+ bdi->wb_mask = bdi->wb_active = 0;
+
+ bdi_wb_init(&bdi->wb, bdi);
for (i = 0; i < NR_BDI_STAT_ITEMS; i++) {
err = percpu_counter_init(&bdi->bdi_stat[i], 0);
@@ -460,7 +535,7 @@ err:
while (i--)
percpu_counter_destroy(&bdi->bdi_stat[i]);
- bdi_remove_from_list(bdi);
+ bdi_wb_shutdown(bdi);
}
return err;
@@ -471,9 +546,7 @@ 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);
--
1.6.2.12.g83676
^ permalink raw reply related [flat|nested] 16+ messages in thread* [PATCH 08/12] writeback: support > 1 flusher thread per bdi
2009-03-22 19:25 [PATCH 0/12] Per-bdi writeback flusher threads #2 Jens Axboe
` (6 preceding siblings ...)
2009-03-22 19:25 ` [PATCH 07/12] writeback: separate the flushing state/task from the bdi Jens Axboe
@ 2009-03-22 19:26 ` Jens Axboe
2009-03-22 19:26 ` [PATCH 09/12] writeback: include default_backing_dev_info in writeback Jens Axboe
` (3 subsequent siblings)
11 siblings, 0 replies; 16+ messages in thread
From: Jens Axboe @ 2009-03-22 19:26 UTC (permalink / raw)
To: linux-kernel, linux-fsdevel
Cc: chris.mason, david, npiggin, hch, akpm, Jens Axboe
Build on the bdi_writeback support by allowing registration of
more than 1 flusher thread. File systems can call bdi_add_flusher_task(bdi)
to add more flusher threads to the device. If they do so, they must also
provide a super_operations function to return the suitable bdi_writeback
struct from any given inode.
Signed-off-by: Jens Axboe <jens.axboe@oracle.com>
---
fs/fs-writeback.c | 47 ++++++++++++++++++--
include/linux/backing-dev.h | 14 ++++++
include/linux/fs.h | 3 +
mm/backing-dev.c | 102 ++++++++++++++++++++++++++++++++++++++----
4 files changed, 151 insertions(+), 15 deletions(-)
diff --git a/fs/fs-writeback.c b/fs/fs-writeback.c
index 34ee130..741e127 100644
--- a/fs/fs-writeback.c
+++ b/fs/fs-writeback.c
@@ -98,16 +98,30 @@ static void wb_start_writeback(struct bdi_writeback *wb, struct super_block *sb,
int bdi_start_writeback(struct backing_dev_info *bdi, struct super_block *sb,
long nr_pages)
{
+ struct bdi_writeback *wb;
+
/*
* This only happens the first time someone kicks this bdi, so put
* it out-of-line.
*/
- if (unlikely(!bdi->wb.task)) {
+ if (unlikely(list_empty(&bdi->wb_list))) {
bdi_add_flusher_task(bdi);
return 1;
}
- wb_start_writeback(&bdi->wb, sb, nr_pages);
+ if (!bdi_wblist_needs_lock(bdi))
+ wb_start_writeback(&bdi->wb, sb, nr_pages);
+ else {
+ int idx;
+
+ idx = srcu_read_lock(&bdi->srcu);
+
+ list_for_each_entry_rcu(wb, &bdi->wb_list, list)
+ wb_start_writeback(wb, sb, nr_pages);
+
+ srcu_read_unlock(&bdi->srcu, idx);
+ }
+
return 0;
}
@@ -259,11 +273,18 @@ restart:
}
/*
- * We have only a single wb per bdi, so just return that.
+ * If the filesystem didn't provide a way to map an inode to a dedicated
+ * flusher thread, it doesn't support more than 1 thread. So we know it's
+ * the default thread, return that.
*/
static inline struct bdi_writeback *inode_get_wb(struct inode *inode)
{
- return &inode_to_bdi(inode)->wb;
+ const struct super_operations *sop = inode->i_sb->s_op;
+
+ if (!sop->inode_get_wb)
+ return &inode_to_bdi(inode)->wb;
+
+ return sop->inode_get_wb(inode);
}
/**
@@ -698,8 +719,24 @@ void generic_sync_bdi_inodes(struct super_block *sb,
struct writeback_control *wbc)
{
struct backing_dev_info *bdi = wbc->bdi;
+ struct bdi_writeback *wb;
+
+ /*
+ * Common case is just a single wb thread and that is embedded in
+ * the bdi, so it doesn't need locking
+ */
+ if (!bdi_wblist_needs_lock(bdi))
+ generic_sync_wb_inodes(&bdi->wb, sb, wbc);
+ else {
+ int idx;
- generic_sync_wb_inodes(&bdi->wb, sb, wbc);
+ idx = srcu_read_lock(&bdi->srcu);
+
+ list_for_each_entry_rcu(wb, &bdi->wb_list, list)
+ generic_sync_wb_inodes(wb, sb, wbc);
+
+ srcu_read_unlock(&bdi->srcu, idx);
+ }
}
/*
diff --git a/include/linux/backing-dev.h b/include/linux/backing-dev.h
index e316349..279bc3f 100644
--- a/include/linux/backing-dev.h
+++ b/include/linux/backing-dev.h
@@ -13,6 +13,7 @@
#include <linux/proportions.h>
#include <linux/kernel.h>
#include <linux/fs.h>
+#include <linux/srcu.h>
#include <asm/atomic.h>
struct page;
@@ -25,6 +26,7 @@ struct dentry;
enum bdi_state {
BDI_pending, /* On its way to being activated */
BDI_wb_alloc, /* Default embedded wb allocated */
+ BDI_wblist_lock, /* bdi->wb_list now needs locking */
BDI_write_congested, /* The write queue is getting full */
BDI_read_congested, /* The read queue is getting full */
BDI_unused, /* Available bits start here */
@@ -41,6 +43,8 @@ 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;
@@ -54,8 +58,11 @@ struct bdi_writeback {
struct super_block *sb;
};
+#define BDI_MAX_FLUSHERS 32
+
struct backing_dev_info {
struct rcu_head rcu_head;
+ struct srcu_struct srcu; /* for wb_list read side protection */
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 */
@@ -74,6 +81,8 @@ struct backing_dev_info {
unsigned int max_ratio, max_prop_frac;
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_active; /* bitmap of active tasks */
unsigned long wb_mask; /* number of registered tasks */
@@ -102,6 +111,11 @@ int bdi_has_dirty_io(struct backing_dev_info *bdi);
extern spinlock_t bdi_lock;
extern struct list_head bdi_list;
+static inline int bdi_wblist_needs_lock(struct backing_dev_info *bdi)
+{
+ return test_bit(BDI_wblist_lock, &bdi->state);
+}
+
static inline int wb_has_dirty_io(struct bdi_writeback *wb)
{
return !list_empty(&wb->b_dirty) ||
diff --git a/include/linux/fs.h b/include/linux/fs.h
index 7d44bda..eb8fbd6 100644
--- a/include/linux/fs.h
+++ b/include/linux/fs.h
@@ -1376,11 +1376,14 @@ extern ssize_t vfs_readv(struct file *, const struct iovec __user *,
extern ssize_t vfs_writev(struct file *, const struct iovec __user *,
unsigned long, loff_t *);
+struct bdi_writeback;
+
struct super_operations {
struct inode *(*alloc_inode)(struct super_block *sb);
void (*destroy_inode)(struct inode *);
void (*dirty_inode) (struct inode *);
+ struct bdi_writeback *(*inode_get_wb) (struct inode *);
int (*write_inode) (struct inode *, int);
void (*drop_inode) (struct inode *);
void (*delete_inode) (struct inode *);
diff --git a/mm/backing-dev.c b/mm/backing-dev.c
index c0cfea0..21406f2 100644
--- a/mm/backing-dev.c
+++ b/mm/backing-dev.c
@@ -225,24 +225,48 @@ static void bdi_flush_io(struct backing_dev_info *bdi)
static int wb_assign_nr(struct backing_dev_info *bdi, struct bdi_writeback *wb)
{
- set_bit(0, &bdi->wb_mask);
- wb->nr = 0;
+ unsigned long mask = BDI_MAX_FLUSHERS - 1;
+ unsigned int nr;
+
+ do {
+ if ((bdi->wb_mask & mask) == mask)
+ return 1;
+
+ nr = find_first_zero_bit(&bdi->wb_mask, BDI_MAX_FLUSHERS);
+ } while (test_and_set_bit(nr, &bdi->wb_mask));
+
+ wb->nr = nr;
return 0;
}
static void bdi_put_wb(struct backing_dev_info *bdi, struct bdi_writeback *wb)
{
clear_bit(wb->nr, &bdi->wb_mask);
- clear_bit(BDI_wb_alloc, &bdi->state);
+
+ if (wb == &bdi->wb)
+ clear_bit(BDI_wb_alloc, &bdi->state);
+ else
+ kfree(wb);
}
static struct bdi_writeback *bdi_new_wb(struct backing_dev_info *bdi)
{
struct bdi_writeback *wb;
- set_bit(BDI_wb_alloc, &bdi->state);
- wb = &bdi->wb;
- wb_assign_nr(bdi, wb);
+ if (!test_and_set_bit(BDI_wb_alloc, &bdi->state)) {
+ wb = &bdi->wb;
+ wb_assign_nr(bdi, wb);
+ } else {
+ wb = kmalloc(sizeof(struct bdi_writeback), GFP_KERNEL);
+ if (wb) {
+ bdi_wb_init(wb, bdi);
+ if (wb_assign_nr(bdi, wb)) {
+ kfree(wb);
+ wb = NULL;
+ }
+ }
+ }
+
return wb;
}
@@ -251,7 +275,22 @@ static int bdi_start_fn(void *ptr)
struct bdi_writeback *wb = ptr;
struct backing_dev_info *bdi = wb->bdi;
struct task_struct *tsk = current;
- int ret;
+ int was_empty, ret;
+
+ /*
+ * Add us to the active bdi_list. If we are adding threads beyond
+ * the default embedded bdi_writeback, then we need to start using
+ * proper locking. Check the list for empty first, then set the
+ * BDI_wblist_lock flag if there's > 1 entry on the list now
+ */
+ spin_lock(&bdi->wb_lock);
+
+ was_empty = list_empty(&bdi->wb_list);
+ list_add_tail_rcu(&wb->list, &bdi->wb_list);
+ if (!was_empty)
+ set_bit(BDI_wblist_lock, &bdi->state);
+
+ spin_unlock(&bdi->wb_lock);
tsk->flags |= PF_FLUSHER | PF_SWAPWRITE;
set_freezable();
@@ -269,13 +308,44 @@ static int bdi_start_fn(void *ptr)
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);
+
+ /*
+ * wait for rcu grace period to end, so we can free wb
+ */
+ synchronize_srcu(&bdi->srcu);
+
bdi_put_wb(bdi, wb);
return ret;
}
int bdi_has_dirty_io(struct backing_dev_info *bdi)
{
- return wb_has_dirty_io(&bdi->wb);
+ struct bdi_writeback *wb;
+ int ret = 0;
+
+ if (!bdi_wblist_needs_lock(bdi))
+ ret = wb_has_dirty_io(&bdi->wb);
+ else {
+ int idx;
+
+ idx = srcu_read_lock(&bdi->srcu);
+
+ list_for_each_entry_rcu(wb, &bdi->wb_list, list) {
+ ret = wb_has_dirty_io(wb);
+ if (ret)
+ break;
+ }
+
+ srcu_read_unlock(&bdi->srcu, idx);
+ }
+
+ return ret;
}
static int bdi_forker_task(void *ptr)
@@ -466,6 +536,8 @@ static int sched_wait(void *word)
*/
static void bdi_wb_shutdown(struct backing_dev_info *bdi)
{
+ struct bdi_writeback *wb;
+
if (!bdi_cap_writeback_dirty(bdi))
return;
@@ -483,9 +555,10 @@ static void bdi_wb_shutdown(struct backing_dev_info *bdi)
spin_unlock_bh(&bdi_lock);
/*
- * Tells flusher task to exit
+ * Tells flusher tasks to exit
*/
- kthread_stop(bdi->wb.task);
+ list_for_each_entry_rcu(wb, &bdi->wb_list, list)
+ kthread_stop(wb->task);
/*
* In case the bdi is freed right after unregister, we need to
@@ -516,7 +589,9 @@ int bdi_init(struct backing_dev_info *bdi)
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->wb_list);
bdi->wb_mask = bdi->wb_active = 0;
bdi_wb_init(&bdi->wb, bdi);
@@ -527,10 +602,15 @@ int bdi_init(struct backing_dev_info *bdi)
goto err;
}
+ err = init_srcu_struct(&bdi->srcu);
+ if (err)
+ goto err;
+
bdi->dirty_exceeded = 0;
err = prop_local_init_percpu(&bdi->completions);
if (err) {
+ cleanup_srcu_struct(&bdi->srcu);
err:
while (i--)
percpu_counter_destroy(&bdi->bdi_stat[i]);
@@ -550,6 +630,8 @@ void bdi_destroy(struct backing_dev_info *bdi)
bdi_unregister(bdi);
+ cleanup_srcu_struct(&bdi->srcu);
+
for (i = 0; i < NR_BDI_STAT_ITEMS; i++)
percpu_counter_destroy(&bdi->bdi_stat[i]);
--
1.6.2.12.g83676
^ permalink raw reply related [flat|nested] 16+ messages in thread* [PATCH 09/12] writeback: include default_backing_dev_info in writeback
2009-03-22 19:25 [PATCH 0/12] Per-bdi writeback flusher threads #2 Jens Axboe
` (7 preceding siblings ...)
2009-03-22 19:26 ` [PATCH 08/12] writeback: support > 1 flusher thread per bdi Jens Axboe
@ 2009-03-22 19:26 ` Jens Axboe
2009-03-22 19:26 ` [PATCH 10/12] writeback: add some debug inode list counters to bdi stats Jens Axboe
` (2 subsequent siblings)
11 siblings, 0 replies; 16+ messages in thread
From: Jens Axboe @ 2009-03-22 19:26 UTC (permalink / raw)
To: linux-kernel, linux-fsdevel
Cc: chris.mason, david, npiggin, hch, akpm, Jens Axboe
We see dirty inodes there occasionally, so better be safe and write them
out.
Signed-off-by: Jens Axboe <jens.axboe@oracle.com>
---
fs/fs-writeback.c | 60 +++++++++++++++++++++++++------------------
include/linux/backing-dev.h | 5 +++
include/linux/writeback.h | 1 +
mm/backing-dev.c | 35 +++++++++++++++----------
4 files changed, 62 insertions(+), 39 deletions(-)
diff --git a/fs/fs-writeback.c b/fs/fs-writeback.c
index 741e127..5fcdcd4 100644
--- a/fs/fs-writeback.c
+++ b/fs/fs-writeback.c
@@ -34,6 +34,10 @@
*/
int nr_pdflush_threads = 0;
+static void generic_sync_wb_inodes(struct bdi_writeback *wb,
+ struct super_block *sb,
+ struct writeback_control *wbc);
+
/**
* writeback_acquire - attempt to get exclusive writeback access to a device
* @bdi: the device's backing_dev_info structure
@@ -149,7 +153,7 @@ int bdi_start_writeback(struct backing_dev_info *bdi, struct super_block *sb,
* 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_kupdated(struct bdi_writeback *wb)
+void wb_kupdated(struct bdi_writeback *wb)
{
long nr_to_write;
struct writeback_control wbc = {
@@ -177,11 +181,7 @@ static void wb_kupdated(struct bdi_writeback *wb)
}
}
-static void generic_sync_wb_inodes(struct bdi_writeback *wb,
- struct super_block *sb,
- struct writeback_control *wbc);
-
-static void wb_writeback(struct bdi_writeback *wb)
+void wb_writeback(struct bdi_writeback *wb)
{
struct writeback_control wbc = {
.bdi = wb->bdi,
@@ -217,6 +217,34 @@ static void wb_writeback(struct bdi_writeback *wb)
}
/*
+ * This will be inlined in bdi_writeback_task() once we get rid of any
+ * dirty inodes on the default_backing_dev_info
+ */
+void wb_do_writeback(struct bdi_writeback *wb)
+{
+ /*
+ * We get here in two cases:
+ *
+ * schedule_timeout() returned because the dirty writeback
+ * interval has elapsed. If that happens, we will be able
+ * to acquire the writeback lock and will proceed to do
+ * kupdated style writeout.
+ *
+ * Someone called bdi_start_writeback(), which will acquire
+ * the writeback lock. This means our writeback_acquire()
+ * below will fail and we call into bdi_pdflush() for
+ * pdflush style writeout.
+ *
+ */
+ if (writeback_acquire(wb))
+ wb_kupdated(wb);
+ else
+ wb_writeback(wb);
+
+ writeback_release(wb);
+}
+
+/*
* Handle writeback of dirty data for the device backed by this bdi. Also
* wakes up periodically and does kupdated style flushing.
*/
@@ -229,26 +257,8 @@ int bdi_writeback_task(struct bdi_writeback *wb)
schedule_timeout(dirty_writeback_interval);
try_to_freeze();
- /*
- * We get here in two cases:
- *
- * schedule_timeout() returned because the dirty writeback
- * interval has elapsed. If that happens, we will be able
- * to acquire the writeback lock and will proceed to do
- * kupdated style writeout.
- *
- * Someone called bdi_start_writeback(), which will acquire
- * the writeback lock. This means our writeback_acquire()
- * below will fail and we call into bdi_pdflush() for
- * pdflush style writeout.
- *
- */
- if (writeback_acquire(wb))
- wb_kupdated(wb);
- else
- wb_writeback(wb);
+ wb_do_writeback(wb);
- writeback_release(wb);
finish_wait(&wb->wait, &wait);
}
diff --git a/include/linux/backing-dev.h b/include/linux/backing-dev.h
index 279bc3f..9dd8cb9 100644
--- a/include/linux/backing-dev.h
+++ b/include/linux/backing-dev.h
@@ -308,6 +308,11 @@ 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->capabilities & BDI_CAP_FLUSH_FORKER;
+}
+
static inline bool mapping_cap_writeback_dirty(struct address_space *mapping)
{
return bdi_cap_writeback_dirty(mapping->backing_dev_info);
diff --git a/include/linux/writeback.h b/include/linux/writeback.h
index f96fea3..5f1d59f 100644
--- a/include/linux/writeback.h
+++ b/include/linux/writeback.h
@@ -69,6 +69,7 @@ void writeback_inodes(struct writeback_control *wbc);
int inode_wait(void *);
void sync_inodes_sb(struct super_block *, int wait);
void sync_inodes(int wait);
+void wb_do_writeback(struct bdi_writeback *wb);
/* writeback.h requires fs.h; it, too, is not included from here. */
static inline void wait_on_inode(struct inode *inode)
diff --git a/mm/backing-dev.c b/mm/backing-dev.c
index 21406f2..7551648 100644
--- a/mm/backing-dev.c
+++ b/mm/backing-dev.c
@@ -357,14 +357,6 @@ static int bdi_forker_task(void *ptr)
struct bdi_writeback *wb;
DEFINE_WAIT(wait);
- /*
- * Should never trigger on the default bdi
- */
- if (wb_has_dirty_io(me)) {
- bdi_flush_io(me->bdi);
- WARN_ON(1);
- }
-
prepare_to_wait(&me->wait, &wait, TASK_INTERRUPTIBLE);
smp_mb();
@@ -372,6 +364,21 @@ static int bdi_forker_task(void *ptr)
schedule();
finish_wait(&me->wait, &wait);
+
+ /*
+ * Ideally we'd like not to see any dirty inodes on the
+ * default_backing_dev_info. Until these are tracked down,
+ * perform the same writeback here that bdi_writeback_task
+ * does. For logic, see comment in
+ * fs/fs-writeback.c:bdi_writeback_task()
+ */
+ if (wb_has_dirty_io(me))
+ wb_do_writeback(me);
+
+ /*
+ * This is our real job - check for pending entries in
+ * bdi_pending_list, and create the tasks that got added
+ */
repeat:
bdi = NULL;
spin_lock_bh(&bdi_lock);
@@ -489,7 +496,7 @@ int bdi_register(struct backing_dev_info *bdi, struct device *parent,
* and add other bdi's to the list. They will get a thread created
* on-demand when they need it.
*/
- if (bdi->capabilities & BDI_CAP_FLUSH_FORKER) {
+ if (bdi_cap_flush_forker(bdi)) {
struct bdi_writeback *wb;
wb = bdi_new_wb(bdi);
@@ -505,12 +512,12 @@ int bdi_register(struct backing_dev_info *bdi, struct device *parent,
ret = -ENOMEM;
goto exit;
}
- } else {
- spin_lock_bh(&bdi_lock);
- list_add_tail_rcu(&bdi->bdi_list, &bdi_list);
- spin_unlock_bh(&bdi_lock);
}
+ spin_lock_bh(&bdi_lock);
+ list_add_tail_rcu(&bdi->bdi_list, &bdi_list);
+ spin_unlock_bh(&bdi_lock);
+
bdi->dev = dev;
bdi_debug_register(bdi, dev_name(dev));
@@ -570,7 +577,7 @@ static void bdi_wb_shutdown(struct backing_dev_info *bdi)
void bdi_unregister(struct backing_dev_info *bdi)
{
if (bdi->dev) {
- if (!(bdi->capabilities & BDI_CAP_FLUSH_FORKER))
+ if (!bdi_cap_flush_forker(bdi))
bdi_wb_shutdown(bdi);
bdi_debug_unregister(bdi);
device_unregister(bdi->dev);
--
1.6.2.12.g83676
^ permalink raw reply related [flat|nested] 16+ messages in thread* [PATCH 10/12] writeback: add some debug inode list counters to bdi stats
2009-03-22 19:25 [PATCH 0/12] Per-bdi writeback flusher threads #2 Jens Axboe
` (8 preceding siblings ...)
2009-03-22 19:26 ` [PATCH 09/12] writeback: include default_backing_dev_info in writeback Jens Axboe
@ 2009-03-22 19:26 ` Jens Axboe
2009-03-22 19:26 ` [PATCH 11/12] writeback: add name to backing_dev_info Jens Axboe
2009-03-22 19:26 ` [PATCH 12/12] writeback: check for registered bdi in flusher add Jens Axboe
11 siblings, 0 replies; 16+ messages in thread
From: Jens Axboe @ 2009-03-22 19:26 UTC (permalink / raw)
To: linux-kernel, linux-fsdevel
Cc: chris.mason, david, npiggin, hch, akpm, Jens Axboe
Not meant for inclusion, just to monitor what is going on while testing
this stuff.
Signed-off-by: Jens Axboe <jens.axboe@oracle.com>
---
mm/backing-dev.c | 24 ++++++++++++++++++++++--
1 files changed, 22 insertions(+), 2 deletions(-)
diff --git a/mm/backing-dev.c b/mm/backing-dev.c
index 7551648..e80c90d 100644
--- a/mm/backing-dev.c
+++ b/mm/backing-dev.c
@@ -43,9 +43,25 @@ static void bdi_debug_init(void)
static int bdi_debug_stats_show(struct seq_file *m, void *v)
{
struct backing_dev_info *bdi = m->private;
+ struct bdi_writeback *wb;
unsigned long background_thresh;
unsigned long dirty_thresh;
unsigned long bdi_thresh;
+ unsigned long nr_dirty, nr_io, nr_more_io, nr_wb;
+ struct inode *inode;
+
+ nr_wb = nr_dirty = nr_io = nr_more_io = 0;
+ spin_lock(&inode_lock);
+ list_for_each_entry(wb, &bdi->wb_list, list) {
+ nr_wb++;
+ list_for_each_entry(inode, &wb->b_dirty, i_list)
+ nr_dirty++;
+ list_for_each_entry(inode, &wb->b_io, i_list)
+ nr_io++;
+ list_for_each_entry(inode, &wb->b_more_io, i_list)
+ nr_more_io++;
+ }
+ spin_unlock(&inode_lock);
get_dirty_limits(&background_thresh, &dirty_thresh, &bdi_thresh, bdi);
@@ -55,12 +71,16 @@ static int bdi_debug_stats_show(struct seq_file *m, void *v)
"BdiReclaimable: %8lu kB\n"
"BdiDirtyThresh: %8lu kB\n"
"DirtyThresh: %8lu kB\n"
- "BackgroundThresh: %8lu kB\n",
+ "BackgroundThresh: %8lu kB\n"
+ "WriteBack threads:%8lu\n"
+ "b_dirty: %8lu kB\n"
+ "b_io: %8lu kB\n"
+ "b_more_io: %8lu kB\n",
(unsigned long) K(bdi_stat(bdi, BDI_WRITEBACK)),
(unsigned long) K(bdi_stat(bdi, BDI_RECLAIMABLE)),
K(bdi_thresh),
K(dirty_thresh),
- K(background_thresh));
+ K(background_thresh), nr_wb, nr_dirty, nr_io, nr_more_io);
#undef K
return 0;
--
1.6.2.12.g83676
^ permalink raw reply related [flat|nested] 16+ messages in thread* [PATCH 11/12] writeback: add name to backing_dev_info
2009-03-22 19:25 [PATCH 0/12] Per-bdi writeback flusher threads #2 Jens Axboe
` (9 preceding siblings ...)
2009-03-22 19:26 ` [PATCH 10/12] writeback: add some debug inode list counters to bdi stats Jens Axboe
@ 2009-03-22 19:26 ` Jens Axboe
2009-03-22 19:26 ` [PATCH 12/12] writeback: check for registered bdi in flusher add Jens Axboe
11 siblings, 0 replies; 16+ messages in thread
From: Jens Axboe @ 2009-03-22 19:26 UTC (permalink / raw)
To: linux-kernel, linux-fsdevel
Cc: chris.mason, david, npiggin, hch, akpm, Jens Axboe
Just for testing purposes, to be able to easier track who does what.
Signed-off-by: Jens Axboe <jens.axboe@oracle.com>
---
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(+), 0 deletions(-)
diff --git a/block/blk-core.c b/block/blk-core.c
index 29bcfac..b147dc6 100644
--- a/block/blk-core.c
+++ b/block/blk-core.c
@@ -517,6 +517,7 @@ struct request_queue *blk_alloc_queue_node(gfp_t gfp_mask, int node_id)
q->backing_dev_info.unplug_io_fn = blk_backing_dev_unplug;
q->backing_dev_info.unplug_io_data = q;
+ q->backing_dev_info.name = "block";
err = bdi_init(&q->backing_dev_info);
if (err) {
kmem_cache_free(blk_requestq_cachep, q);
diff --git a/drivers/block/aoe/aoeblk.c b/drivers/block/aoe/aoeblk.c
index 2307a27..0efb8fc 100644
--- a/drivers/block/aoe/aoeblk.c
+++ b/drivers/block/aoe/aoeblk.c
@@ -265,6 +265,7 @@ aoeblk_gdalloc(void *vp)
}
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_mempool;
spin_lock_irqsave(&d->lock, flags);
diff --git a/drivers/char/mem.c b/drivers/char/mem.c
index 3586b3b..45b485f 100644
--- a/drivers/char/mem.c
+++ b/drivers/char/mem.c
@@ -847,6 +847,7 @@ 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 6ec80c0..d95cfdf 100644
--- a/fs/btrfs/disk-io.c
+++ b/fs/btrfs/disk-io.c
@@ -1342,6 +1342,7 @@ static void btrfs_unplug_io_fn(struct backing_dev_info *bdi, struct page *page)
static int setup_bdi(struct btrfs_fs_info *info, struct backing_dev_info *bdi)
{
+ bdi->name = "btrfs";
bdi_init(bdi);
bdi->ra_pages = default_backing_dev_info.ra_pages;
bdi->state = 0;
diff --git a/fs/char_dev.c b/fs/char_dev.c
index 38f7122..350ef9c 100644
--- a/fs/char_dev.c
+++ b/fs/char_dev.c
@@ -32,6 +32,7 @@
* - 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 5d349d3..9a266cd 100644
--- a/fs/configfs/inode.c
+++ b/fs/configfs/inode.c
@@ -46,6 +46,7 @@ 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 459b73d..21ed16c 100644
--- a/fs/fuse/inode.c
+++ b/fs/fuse/inode.c
@@ -481,6 +481,7 @@ int fuse_conn_init(struct fuse_conn *fc, struct super_block *sb)
INIT_LIST_HEAD(&fc->bg_queue);
INIT_LIST_HEAD(&fc->entry);
atomic_set(&fc->num_waiting, 0);
+ 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 9b800d9..042f28e 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 574158a..5d3fcac 100644
--- a/fs/nfs/client.c
+++ b/fs/nfs/client.c
@@ -842,6 +842,7 @@ 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 1c9efb4..02bf178 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 b7e6ac7..d34bfa4 100644
--- a/fs/ramfs/inode.c
+++ b/fs/ramfs/inode.c
@@ -43,6 +43,7 @@ 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 dfa3d94..3383f15 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 1182b66..462bda8 100644
--- a/fs/ubifs/super.c
+++ b/fs/ubifs/super.c
@@ -1906,6 +1906,7 @@ 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 9dd8cb9..3d373d4 100644
--- a/include/linux/backing-dev.h
+++ b/include/linux/backing-dev.h
@@ -72,6 +72,8 @@ 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 9edb5c4..c63970e 100644
--- a/kernel/cgroup.c
+++ b/kernel/cgroup.c
@@ -564,6 +564,7 @@ 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 e80c90d..981e8e8 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 | BDI_CAP_FLUSH_FORKER,
diff --git a/mm/swap_state.c b/mm/swap_state.c
index 3ecea98..323da00 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,
};
--
1.6.2.12.g83676
^ permalink raw reply related [flat|nested] 16+ messages in thread* [PATCH 12/12] writeback: check for registered bdi in flusher add
2009-03-22 19:25 [PATCH 0/12] Per-bdi writeback flusher threads #2 Jens Axboe
` (10 preceding siblings ...)
2009-03-22 19:26 ` [PATCH 11/12] writeback: add name to backing_dev_info Jens Axboe
@ 2009-03-22 19:26 ` Jens Axboe
11 siblings, 0 replies; 16+ messages in thread
From: Jens Axboe @ 2009-03-22 19:26 UTC (permalink / raw)
To: linux-kernel, linux-fsdevel
Cc: chris.mason, david, npiggin, hch, akpm, Jens Axboe
Also a debugging aid.
Signed-off-by: Jens Axboe <jens.axboe@oracle.com>
---
include/linux/backing-dev.h | 1 +
mm/backing-dev.c | 6 ++++++
2 files changed, 7 insertions(+), 0 deletions(-)
diff --git a/include/linux/backing-dev.h b/include/linux/backing-dev.h
index 3d373d4..c65b219 100644
--- a/include/linux/backing-dev.h
+++ b/include/linux/backing-dev.h
@@ -29,6 +29,7 @@ enum bdi_state {
BDI_wblist_lock, /* bdi->wb_list now needs locking */
BDI_write_congested, /* The write queue is getting full */
BDI_read_congested, /* The read queue is getting full */
+ BDI_registered,
BDI_unused, /* Available bits start here */
};
diff --git a/mm/backing-dev.c b/mm/backing-dev.c
index 981e8e8..18faf79 100644
--- a/mm/backing-dev.c
+++ b/mm/backing-dev.c
@@ -474,6 +474,11 @@ void bdi_add_flusher_task(struct backing_dev_info *bdi)
if (!bdi_cap_writeback_dirty(bdi))
return;
+ if (!test_bit(BDI_registered, &bdi->state)) {
+ printk("bdi %p/%s is not registered!\n", bdi, bdi->name);
+ return;
+ }
+
/*
* Someone already marked this pending for task creation
*/
@@ -541,6 +546,7 @@ int bdi_register(struct backing_dev_info *bdi, struct device *parent,
bdi->dev = dev;
bdi_debug_register(bdi, dev_name(dev));
+ set_bit(BDI_registered, &bdi->state);
exit:
return ret;
--
1.6.2.12.g83676
^ permalink raw reply related [flat|nested] 16+ messages in thread