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Subject[patch 30/52] fs: icache lock lru/writeback lists
Add a new lock, wb_inode_list_lock, to protect i_list and various lists
which the inode can be put onto.

Signed-off-by: Nick Piggin <npiggin@suse.de>
---
fs/fs-writeback.c | 40 ++++++++++++++++++++++++++++++++++++++--
fs/inode.c | 43 +++++++++++++++++++++++++++++++++++--------
include/linux/writeback.h | 1 +
mm/backing-dev.c | 4 ++++
4 files changed, 78 insertions(+), 10 deletions(-)
Index: linux-2.6/fs/fs-writeback.c
===================================================================
--- linux-2.6.orig/fs/fs-writeback.c
+++ linux-2.6/fs/fs-writeback.c
@@ -287,6 +287,7 @@ static void redirty_tail(struct inode *i
{
struct bdi_writeback *wb = &inode_to_bdi(inode)->wb;

+ assert_spin_locked(&wb_inode_list_lock);
if (!list_empty(&wb->b_dirty)) {
struct inode *tail;

@@ -304,6 +305,7 @@ static void requeue_io(struct inode *ino
{
struct bdi_writeback *wb = &inode_to_bdi(inode)->wb;

+ assert_spin_locked(&wb_inode_list_lock);
list_move(&inode->i_list, &wb->b_more_io);
}

@@ -344,6 +346,7 @@ static void move_expired_inodes(struct l
struct inode *inode;
int do_sb_sort = 0;

+ assert_spin_locked(&wb_inode_list_lock);
while (!list_empty(delaying_queue)) {
inode = list_entry(delaying_queue->prev, struct inode, i_list);
if (older_than_this &&
@@ -399,11 +402,13 @@ static void inode_wait_for_writeback(str

wqh = bit_waitqueue(&inode->i_state, __I_SYNC);
while (inode->i_state & I_SYNC) {
+ spin_unlock(&wb_inode_list_lock);
spin_unlock(&inode->i_lock);
spin_unlock(&inode_lock);
__wait_on_bit(wqh, &wq, inode_wait, TASK_UNINTERRUPTIBLE);
spin_lock(&inode_lock);
spin_lock(&inode->i_lock);
+ spin_lock(&wb_inode_list_lock);
}
}

@@ -457,6 +462,7 @@ writeback_single_inode(struct inode *ino
/* Set I_SYNC, reset I_DIRTY_PAGES */
inode->i_state |= I_SYNC;
inode->i_state &= ~I_DIRTY_PAGES;
+ spin_unlock(&wb_inode_list_lock);
spin_unlock(&inode->i_lock);
spin_unlock(&inode_lock);

@@ -493,6 +499,7 @@ writeback_single_inode(struct inode *ino

spin_lock(&inode_lock);
spin_lock(&inode->i_lock);
+ spin_lock(&wb_inode_list_lock);
inode->i_state &= ~I_SYNC;
if (!(inode->i_state & (I_FREEING | I_CLEAR))) {
if ((inode->i_state & I_DIRTY_PAGES) && wbc->for_kupdate) {
@@ -623,23 +630,31 @@ static int writeback_sb_inodes(struct su
struct bdi_writeback *wb,
struct writeback_control *wbc)
{
+again:
while (!list_empty(&wb->b_io)) {
long pages_skipped;
struct inode *inode = list_entry(wb->b_io.prev,
struct inode, i_list);
+ if (!spin_trylock(&inode->i_lock)) {
+ spin_unlock(&wb_inode_list_lock);
+ spin_lock(&wb_inode_list_lock);
+ goto again;
+ }
if (wbc->sb && sb != inode->i_sb) {
/* super block given and doesn't
match, skip this inode */
redirty_tail(inode);
+ spin_unlock(&inode->i_lock);
continue;
}
- if (sb != inode->i_sb)
+ if (sb != inode->i_sb) {
/* finish with this superblock */
+ spin_unlock(&inode->i_lock);
return 0;
- spin_lock(&inode->i_lock);
+ }
if (inode->i_state & (I_NEW | I_WILL_FREE)) {
- spin_unlock(&inode->i_lock);
requeue_io(inode);
+ spin_unlock(&inode->i_lock);
continue;
}
/*
@@ -662,11 +677,13 @@ static int writeback_sb_inodes(struct su
*/
redirty_tail(inode);
}
+ spin_unlock(&wb_inode_list_lock);
spin_unlock(&inode->i_lock);
spin_unlock(&inode_lock);
iput(inode);
cond_resched();
spin_lock(&inode_lock);
+ spin_lock(&wb_inode_list_lock);
if (wbc->nr_to_write <= 0) {
wbc->more_io = 1;
return 1;
@@ -685,6 +702,9 @@ static void writeback_inodes_wb(struct b

wbc->wb_start = jiffies; /* livelock avoidance */
spin_lock(&inode_lock);
+again:
+ spin_lock(&wb_inode_list_lock);
+
if (!wbc->for_kupdate || list_empty(&wb->b_io))
queue_io(wb, wbc->older_than_this);

@@ -697,13 +717,23 @@ static void writeback_inodes_wb(struct b
if (wbc->sb && sb != wbc->sb) {
/* super block given and doesn't
match, skip this inode */
+ if (!spin_trylock(&inode->i_lock)) {
+ spin_unlock(&wb_inode_list_lock);
+ goto again;
+ }
redirty_tail(inode);
+ spin_unlock(&inode->i_lock);
continue;
}
state = pin_sb_for_writeback(wbc, sb);

if (state == SB_PIN_FAILED) {
+ if (!spin_trylock(&inode->i_lock)) {
+ spin_unlock(&wb_inode_list_lock);
+ goto again;
+ }
requeue_io(inode);
+ spin_unlock(&inode->i_lock);
continue;
}
ret = writeback_sb_inodes(sb, wb, wbc);
@@ -713,6 +743,7 @@ static void writeback_inodes_wb(struct b
if (ret)
break;
}
+ spin_unlock(&wb_inode_list_lock);
spin_unlock(&inode_lock);
/* Leave any unwritten inodes on b_io */
}
@@ -825,12 +856,21 @@ static long wb_writeback(struct bdi_writ
* become available for writeback. Otherwise
* we'll just busyloop.
*/
+retry:
spin_lock(&inode_lock);
+ spin_lock(&wb_inode_list_lock);
if (!list_empty(&wb->b_more_io)) {
inode = list_entry(wb->b_more_io.prev,
struct inode, i_list);
+ if (!spin_trylock(&inode->i_lock)) {
+ spin_unlock(&wb_inode_list_lock);
+ spin_unlock(&inode_lock);
+ goto retry;
+ }
inode_wait_for_writeback(inode);
+ spin_unlock(&inode->i_lock);
}
+ spin_unlock(&wb_inode_list_lock);
spin_unlock(&inode_lock);
}

@@ -1142,7 +1182,9 @@ void __mark_inode_dirty(struct inode *in
}

inode->dirtied_when = jiffies;
+ spin_lock(&wb_inode_list_lock);
list_move(&inode->i_list, &wb->b_dirty);
+ spin_unlock(&wb_inode_list_lock);
}
}
out:
@@ -1306,7 +1348,9 @@ int write_inode_now(struct inode *inode,
might_sleep();
spin_lock(&inode_lock);
spin_lock(&inode->i_lock);
+ spin_lock(&wb_inode_list_lock);
ret = writeback_single_inode(inode, &wbc);
+ spin_unlock(&wb_inode_list_lock);
spin_unlock(&inode->i_lock);
spin_unlock(&inode_lock);
if (sync)
@@ -1332,7 +1376,9 @@ int sync_inode(struct inode *inode, stru

spin_lock(&inode_lock);
spin_lock(&inode->i_lock);
+ spin_lock(&wb_inode_list_lock);
ret = writeback_single_inode(inode, wbc);
+ spin_unlock(&wb_inode_list_lock);
spin_unlock(&inode->i_lock);
spin_unlock(&inode_lock);
return ret;
Index: linux-2.6/fs/inode.c
===================================================================
--- linux-2.6.orig/fs/inode.c
+++ linux-2.6/fs/inode.c
@@ -32,6 +32,8 @@
* s_inodes, i_sb_list
* inode_hash_lock protects:
* inode hash table, i_hash
+ * wb_inode_list_lock protects:
+ * inode_in_use, inode_unused, b_io, b_more_io, b_dirty, i_list
* inode->i_lock protects:
* i_state, i_count
*
@@ -39,6 +41,7 @@
* inode_lock
* sb_inode_list_lock
* inode->i_lock
+ * wb_inode_list_lock
* inode_hash_lock
*/
/*
@@ -100,6 +103,7 @@ static struct hlist_head *inode_hashtabl
*/
DEFINE_SPINLOCK(inode_lock);
DEFINE_SPINLOCK(sb_inode_list_lock);
+DEFINE_SPINLOCK(wb_inode_list_lock);
DEFINE_SPINLOCK(inode_hash_lock);

/*
@@ -309,8 +313,11 @@ void __iget(struct inode *inode)
if (inode->i_count > 1)
return;

- if (!(inode->i_state & (I_DIRTY|I_SYNC)))
+ if (!(inode->i_state & (I_DIRTY|I_SYNC))) {
+ spin_lock(&wb_inode_list_lock);
list_move(&inode->i_list, &inode_in_use);
+ spin_unlock(&wb_inode_list_lock);
+ }
inodes_stat.nr_unused--;
}

@@ -413,7 +420,9 @@ static int invalidate_list(struct list_h
}
invalidate_inode_buffers(inode);
if (!inode->i_count) {
+ spin_lock(&wb_inode_list_lock);
list_move(&inode->i_list, dispose);
+ spin_unlock(&wb_inode_list_lock);
WARN_ON(inode->i_state & I_NEW);
inode->i_state |= I_FREEING;
spin_unlock(&inode->i_lock);
@@ -492,6 +501,8 @@ static void prune_icache(int nr_to_scan)

down_read(&iprune_sem);
spin_lock(&inode_lock);
+again:
+ spin_lock(&wb_inode_list_lock);
for (nr_scanned = 0; nr_scanned < nr_to_scan; nr_scanned++) {
struct inode *inode;

@@ -500,13 +511,17 @@ static void prune_icache(int nr_to_scan)

inode = list_entry(inode_unused.prev, struct inode, i_list);

- spin_lock(&inode->i_lock);
+ if (!spin_trylock(&inode->i_lock)) {
+ spin_unlock(&wb_inode_list_lock);
+ goto again;
+ }
if (inode->i_state || inode->i_count) {
list_move(&inode->i_list, &inode_unused);
spin_unlock(&inode->i_lock);
continue;
}
if (inode_has_buffers(inode) || inode->i_data.nrpages) {
+ spin_unlock(&wb_inode_list_lock);
__iget(inode);
spin_unlock(&inode->i_lock);
spin_unlock(&inode_lock);
@@ -515,11 +530,16 @@ static void prune_icache(int nr_to_scan)
0, -1);
iput(inode);
spin_lock(&inode_lock);
+again2:
+ spin_lock(&wb_inode_list_lock);

if (inode != list_entry(inode_unused.next,
struct inode, i_list))
continue; /* wrong inode or list_empty */
- spin_lock(&inode->i_lock);
+ if (!spin_trylock(&inode->i_lock)) {
+ spin_unlock(&wb_inode_list_lock);
+ goto again2;
+ }
if (!can_unuse(inode)) {
spin_unlock(&inode->i_lock);
continue;
@@ -537,6 +557,7 @@ static void prune_icache(int nr_to_scan)
else
__count_vm_events(PGINODESTEAL, reap);
spin_unlock(&inode_lock);
+ spin_unlock(&wb_inode_list_lock);

dispose_list(&freeable);
up_read(&iprune_sem);
@@ -660,7 +681,9 @@ __inode_add_to_lists(struct super_block
spin_lock(&sb_inode_list_lock);
list_add(&inode->i_sb_list, &sb->s_inodes);
spin_unlock(&sb_inode_list_lock);
+ spin_lock(&wb_inode_list_lock);
list_add(&inode->i_list, &inode_in_use);
+ spin_unlock(&wb_inode_list_lock);
if (head) {
spin_lock(&inode_hash_lock);
hlist_add_head(&inode->i_hash, head);
@@ -1290,7 +1313,9 @@ void generic_delete_inode(struct inode *
{
const struct super_operations *op = inode->i_sb->s_op;

+ spin_lock(&wb_inode_list_lock);
list_del_init(&inode->i_list);
+ spin_unlock(&wb_inode_list_lock);
list_del_init(&inode->i_sb_list);
spin_unlock(&sb_inode_list_lock);
WARN_ON(inode->i_state & I_NEW);
@@ -1335,8 +1360,11 @@ int generic_detach_inode(struct inode *i
struct super_block *sb = inode->i_sb;

if (!hlist_unhashed(&inode->i_hash)) {
- if (!(inode->i_state & (I_DIRTY|I_SYNC)))
+ if (!(inode->i_state & (I_DIRTY|I_SYNC))) {
+ spin_lock(&wb_inode_list_lock);
list_move(&inode->i_list, &inode_unused);
+ spin_unlock(&wb_inode_list_lock);
+ }
inodes_stat.nr_unused++;
if (sb->s_flags & MS_ACTIVE) {
spin_unlock(&inode->i_lock);
@@ -1360,7 +1388,9 @@ int generic_detach_inode(struct inode *i
hlist_del_init(&inode->i_hash);
spin_unlock(&inode_hash_lock);
}
+ spin_lock(&wb_inode_list_lock);
list_del_init(&inode->i_list);
+ spin_unlock(&wb_inode_list_lock);
list_del_init(&inode->i_sb_list);
spin_unlock(&sb_inode_list_lock);
WARN_ON(inode->i_state & I_NEW);
@@ -1432,17 +1462,17 @@ void iput(struct inode *inode)
if (inode) {
BUG_ON(inode->i_state == I_CLEAR);

-retry:
+retry1:
spin_lock(&inode->i_lock);
if (inode->i_count == 1) {
if (!spin_trylock(&inode_lock)) {
+retry2:
spin_unlock(&inode->i_lock);
- goto retry;
+ goto retry1;
}
if (!spin_trylock(&sb_inode_list_lock)) {
spin_unlock(&inode_lock);
- spin_unlock(&inode->i_lock);
- goto retry;
+ goto retry2;
}
inode->i_count--;
iput_final(inode);
Index: linux-2.6/include/linux/writeback.h
===================================================================
--- linux-2.6.orig/include/linux/writeback.h
+++ linux-2.6/include/linux/writeback.h
@@ -11,6 +11,7 @@ struct backing_dev_info;

extern spinlock_t inode_lock;
extern spinlock_t sb_inode_list_lock;
+extern spinlock_t wb_inode_list_lock;
extern spinlock_t inode_hash_lock;
extern struct list_head inode_in_use;
extern struct list_head inode_unused;
Index: linux-2.6/mm/backing-dev.c
===================================================================
--- linux-2.6.orig/mm/backing-dev.c
+++ linux-2.6/mm/backing-dev.c
@@ -78,6 +78,7 @@ static int bdi_debug_stats_show(struct s
*/
nr_wb = nr_dirty = nr_io = nr_more_io = 0;
spin_lock(&inode_lock);
+ spin_lock(&wb_inode_list_lock);
list_for_each_entry(wb, &bdi->wb_list, list) {
nr_wb++;
list_for_each_entry(inode, &wb->b_dirty, i_list)
@@ -87,6 +88,7 @@ static int bdi_debug_stats_show(struct s
list_for_each_entry(inode, &wb->b_more_io, i_list)
nr_more_io++;
}
+ spin_unlock(&wb_inode_list_lock);
spin_unlock(&inode_lock);

get_dirty_limits(&background_thresh, &dirty_thresh, &bdi_thresh, bdi);
@@ -712,9 +714,11 @@ void bdi_destroy(struct backing_dev_info
struct bdi_writeback *dst = &default_backing_dev_info.wb;

spin_lock(&inode_lock);
+ spin_lock(&wb_inode_list_lock);
list_splice(&bdi->wb.b_dirty, &dst->b_dirty);
list_splice(&bdi->wb.b_io, &dst->b_io);
list_splice(&bdi->wb.b_more_io, &dst->b_more_io);
+ spin_unlock(&wb_inode_list_lock);
spin_unlock(&inode_lock);
}




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