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Subject[PATCH 04/17] fs: icache lock i_state
Date
From: Nick Piggin <npiggin@suse.de>

We currently protect the per-inode state flags with the inode_lock.
Using a global lock to protect per-object state is overkill when we
coul duse a per-inode lock to protect the state. Use the
inode->i_lock for this, and wrap all the state changes and checks
with the inode->i_lock.

Signed-off-by: Nick Piggin <npiggin@suse.de>
Signed-off-by: Dave Chinner <dchinner@redhat.com>
---
fs/drop_caches.c | 9 ++++--
fs/fs-writeback.c | 29 +++++++++++++++--
fs/inode.c | 86 +++++++++++++++++++++++++++++++++++++++++++++-------
fs/nilfs2/gcdat.c | 1 +
fs/quota/dquot.c | 12 ++++---
5 files changed, 113 insertions(+), 24 deletions(-)
diff --git a/fs/drop_caches.c b/fs/drop_caches.c
index ab69ae7..45bdf88 100644
--- a/fs/drop_caches.c
+++ b/fs/drop_caches.c
@@ -19,11 +19,14 @@ static void drop_pagecache_sb(struct super_block *sb, void *unused)
spin_lock(&inode_lock);
spin_lock(&sb_inode_list_lock);
list_for_each_entry(inode, &sb->s_inodes, i_sb_list) {
- if (inode->i_state & (I_FREEING|I_WILL_FREE|I_NEW))
- continue;
- if (inode->i_mapping->nrpages == 0)
+ spin_lock(&inode->i_lock);
+ if (inode->i_state & (I_FREEING|I_WILL_FREE|I_NEW)
+ || inode->i_mapping->nrpages == 0) {
+ spin_unlock(&inode->i_lock);
continue;
+ }
__iget(inode);
+ spin_unlock(&inode->i_lock);
spin_unlock(&sb_inode_list_lock);
spin_unlock(&inode_lock);
invalidate_mapping_pages(inode->i_mapping, 0, -1);
diff --git a/fs/fs-writeback.c b/fs/fs-writeback.c
index 9adc9d9..7bd1aef 100644
--- a/fs/fs-writeback.c
+++ b/fs/fs-writeback.c
@@ -280,10 +280,12 @@ static void inode_wait_for_writeback(struct inode *inode)
wait_queue_head_t *wqh;

wqh = bit_waitqueue(&inode->i_state, __I_SYNC);
- while (inode->i_state & I_SYNC) {
+ while (inode->i_state & I_SYNC) {
+ 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);
}
}

@@ -337,6 +339,7 @@ writeback_single_inode(struct inode *inode, struct writeback_control *wbc)
/* Set I_SYNC, reset I_DIRTY_PAGES */
inode->i_state |= I_SYNC;
inode->i_state &= ~I_DIRTY_PAGES;
+ spin_unlock(&inode->i_lock);
spin_unlock(&inode_lock);

ret = do_writepages(mapping, wbc);
@@ -358,8 +361,10 @@ writeback_single_inode(struct inode *inode, struct writeback_control *wbc)
* write_inode()
*/
spin_lock(&inode_lock);
+ spin_lock(&inode->i_lock);
dirty = inode->i_state & I_DIRTY;
inode->i_state &= ~(I_DIRTY_SYNC | I_DIRTY_DATASYNC);
+ spin_unlock(&inode->i_lock);
spin_unlock(&inode_lock);
/* Don't write the inode if only I_DIRTY_PAGES was set */
if (dirty & (I_DIRTY_SYNC | I_DIRTY_DATASYNC)) {
@@ -369,6 +374,7 @@ writeback_single_inode(struct inode *inode, struct writeback_control *wbc)
}

spin_lock(&inode_lock);
+ spin_lock(&inode->i_lock);
inode->i_state &= ~I_SYNC;
if (!(inode->i_state & I_FREEING)) {
if (mapping_tagged(mapping, PAGECACHE_TAG_DIRTY)) {
@@ -479,7 +485,9 @@ static int writeback_sb_inodes(struct super_block *sb, struct bdi_writeback *wb,
return 0;
}

+ spin_lock(&inode->i_lock);
if (inode->i_state & (I_NEW | I_WILL_FREE)) {
+ spin_unlock(&inode->i_lock);
requeue_io(inode);
continue;
}
@@ -487,8 +495,10 @@ static int writeback_sb_inodes(struct super_block *sb, struct bdi_writeback *wb,
* Was this inode dirtied after sync_sb_inodes was called?
* This keeps sync from extra jobs and livelock.
*/
- if (inode_dirtied_after(inode, wbc->wb_start))
+ if (inode_dirtied_after(inode, wbc->wb_start)) {
+ spin_unlock(&inode->i_lock);
return 1;
+ }

BUG_ON(inode->i_state & I_FREEING);
__iget(inode);
@@ -501,6 +511,7 @@ static int writeback_sb_inodes(struct super_block *sb, struct bdi_writeback *wb,
*/
redirty_tail(inode);
}
+ spin_unlock(&inode->i_lock);
spin_unlock(&inode_lock);
iput(inode);
cond_resched();
@@ -936,6 +947,7 @@ void __mark_inode_dirty(struct inode *inode, int flags)
block_dump___mark_inode_dirty(inode);

spin_lock(&inode_lock);
+ spin_lock(&inode->i_lock);
if ((inode->i_state & flags) != flags) {
const int was_dirty = inode->i_state & I_DIRTY;

@@ -986,6 +998,7 @@ void __mark_inode_dirty(struct inode *inode, int flags)
}
}
out:
+ spin_unlock(&inode->i_lock);
spin_unlock(&inode_lock);

if (wakeup_bdi)
@@ -1033,12 +1046,16 @@ static void wait_sb_inodes(struct super_block *sb)
list_for_each_entry(inode, &sb->s_inodes, i_sb_list) {
struct address_space *mapping;

- if (inode->i_state & (I_FREEING|I_WILL_FREE|I_NEW))
- continue;
mapping = inode->i_mapping;
if (mapping->nrpages == 0)
continue;
+ spin_lock(&inode->i_lock);
+ if (inode->i_state & (I_FREEING|I_WILL_FREE|I_NEW)) {
+ spin_unlock(&inode->i_lock);
+ continue;
+ }
__iget(inode);
+ spin_unlock(&inode->i_lock);
spin_unlock(&sb_inode_list_lock);
spin_unlock(&inode_lock);
/*
@@ -1165,7 +1182,9 @@ int write_inode_now(struct inode *inode, int sync)

might_sleep();
spin_lock(&inode_lock);
+ spin_lock(&inode->i_lock);
ret = writeback_single_inode(inode, &wbc);
+ spin_unlock(&inode->i_lock);
spin_unlock(&inode_lock);
if (sync)
inode_sync_wait(inode);
@@ -1189,7 +1208,9 @@ int sync_inode(struct inode *inode, struct writeback_control *wbc)
int ret;

spin_lock(&inode_lock);
+ spin_lock(&inode->i_lock);
ret = writeback_single_inode(inode, wbc);
+ spin_unlock(&inode->i_lock);
spin_unlock(&inode_lock);
return ret;
}
diff --git a/fs/inode.c b/fs/inode.c
index 9d7ffb1..906a4ad 100644
--- a/fs/inode.c
+++ b/fs/inode.c
@@ -31,10 +31,13 @@
* s_inodes, i_sb_list
* inode_hash_lock protects:
* inode hash table, i_hash
+ * inode->i_lock protects:
+ * i_state
*
* Ordering:
* inode_lock
* sb_inode_list_lock
+ * inode->i_lock
* inode_lock
* inode_hash_lock
*/
@@ -296,6 +299,8 @@ static void init_once(void *foo)
*/
void __iget(struct inode *inode)
{
+ assert_spin_locked(&inode->i_lock);
+
if (atomic_inc_return(&inode->i_count) != 1)
return;

@@ -396,16 +401,21 @@ static int invalidate_list(struct list_head *head, struct list_head *dispose)
if (tmp == head)
break;
inode = list_entry(tmp, struct inode, i_sb_list);
- if (inode->i_state & I_NEW)
+ spin_lock(&inode->i_lock);
+ if (inode->i_state & I_NEW) {
+ spin_unlock(&inode->i_lock);
continue;
+ }
invalidate_inode_buffers(inode);
if (!atomic_read(&inode->i_count)) {
list_move(&inode->i_list, dispose);
WARN_ON(inode->i_state & I_NEW);
inode->i_state |= I_FREEING;
+ spin_unlock(&inode->i_lock);
count++;
continue;
}
+ spin_unlock(&inode->i_lock);
busy = 1;
}
/* only unused inodes may be cached with i_count zero */
@@ -484,12 +494,15 @@ static void prune_icache(int nr_to_scan)

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

+ spin_lock(&inode->i_lock);
if (inode->i_state || atomic_read(&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) {
__iget(inode);
+ spin_unlock(&inode->i_lock);
spin_unlock(&inode_lock);
if (remove_inode_buffers(inode))
reap += invalidate_mapping_pages(&inode->i_data,
@@ -500,12 +513,16 @@ static void prune_icache(int nr_to_scan)
if (inode != list_entry(inode_unused.next,
struct inode, i_list))
continue; /* wrong inode or list_empty */
- if (!can_unuse(inode))
+ spin_lock(&inode->i_lock);
+ if (!can_unuse(inode)) {
+ spin_unlock(&inode->i_lock);
continue;
+ }
}
list_move(&inode->i_list, &freeable);
WARN_ON(inode->i_state & I_NEW);
inode->i_state |= I_FREEING;
+ spin_unlock(&inode->i_lock);
nr_pruned++;
}
inodes_stat.nr_unused -= nr_pruned;
@@ -568,8 +585,14 @@ repeat:
hlist_for_each_entry(inode, node, head, i_hash) {
if (inode->i_sb != sb)
continue;
- if (!test(inode, data))
+ if (!spin_trylock(&inode->i_lock)) {
+ spin_unlock(&inode_hash_lock);
+ goto repeat;
+ }
+ if (!test(inode, data)) {
+ spin_unlock(&inode->i_lock);
continue;
+ }
if (inode->i_state & (I_FREEING|I_WILL_FREE)) {
spin_unlock(&inode_hash_lock);
__wait_on_freeing_inode(inode);
@@ -598,6 +621,10 @@ repeat:
continue;
if (inode->i_sb != sb)
continue;
+ if (!spin_trylock(&inode->i_lock)) {
+ spin_unlock(&inode_hash_lock);
+ goto repeat;
+ }
if (inode->i_state & (I_FREEING|I_WILL_FREE)) {
spin_unlock(&inode_hash_lock);
__wait_on_freeing_inode(inode);
@@ -624,10 +651,10 @@ __inode_add_to_lists(struct super_block *sb, struct hlist_head *head,
struct inode *inode)
{
inodes_stat.nr_inodes++;
- list_add(&inode->i_list, &inode_in_use);
spin_lock(&sb_inode_list_lock);
list_add(&inode->i_sb_list, &sb->s_inodes);
spin_unlock(&sb_inode_list_lock);
+ list_add(&inode->i_list, &inode_in_use);
if (head) {
spin_lock(&inode_hash_lock);
hlist_add_head(&inode->i_hash, head);
@@ -684,9 +711,9 @@ struct inode *new_inode(struct super_block *sb)
inode = alloc_inode(sb);
if (inode) {
spin_lock(&inode_lock);
- __inode_add_to_lists(sb, NULL, inode);
inode->i_ino = ++last_ino;
inode->i_state = 0;
+ __inode_add_to_lists(sb, NULL, inode);
spin_unlock(&inode_lock);
}
return inode;
@@ -753,8 +780,8 @@ static struct inode *get_new_inode(struct super_block *sb,
if (set(inode, data))
goto set_failed;

- __inode_add_to_lists(sb, head, inode);
inode->i_state = I_NEW;
+ __inode_add_to_lists(sb, head, inode);
spin_unlock(&inode_lock);

/* Return the locked inode with I_NEW set, the
@@ -769,6 +796,7 @@ static struct inode *get_new_inode(struct super_block *sb,
* allocated.
*/
__iget(old);
+ spin_unlock(&old->i_lock);
spin_unlock(&inode_lock);
destroy_inode(inode);
inode = old;
@@ -777,6 +805,7 @@ static struct inode *get_new_inode(struct super_block *sb,
return inode;

set_failed:
+ spin_unlock(&inode->i_lock);
spin_unlock(&inode_lock);
destroy_inode(inode);
return NULL;
@@ -800,8 +829,8 @@ static struct inode *get_new_inode_fast(struct super_block *sb,
old = find_inode_fast(sb, head, ino);
if (!old) {
inode->i_ino = ino;
- __inode_add_to_lists(sb, head, inode);
inode->i_state = I_NEW;
+ __inode_add_to_lists(sb, head, inode);
spin_unlock(&inode_lock);

/* Return the locked inode with I_NEW set, the
@@ -816,6 +845,7 @@ static struct inode *get_new_inode_fast(struct super_block *sb,
* allocated.
*/
__iget(old);
+ spin_unlock(&old->i_lock);
spin_unlock(&inode_lock);
destroy_inode(inode);
inode = old;
@@ -857,6 +887,7 @@ ino_t iunique(struct super_block *sb, ino_t max_reserved)
res = counter++;
head = inode_hashtable + hash(sb, res);
inode = find_inode_fast(sb, head, res);
+ spin_unlock(&inode->i_lock);
} while (inode != NULL);
spin_unlock(&inode_lock);

@@ -866,18 +897,24 @@ EXPORT_SYMBOL(iunique);

struct inode *igrab(struct inode *inode)
{
+ struct inode *ret = inode;
+
spin_lock(&inode_lock);
- if (!(inode->i_state & (I_FREEING|I_WILL_FREE)))
+ spin_lock(&inode->i_lock);
+ if (!(inode->i_state & (I_FREEING|I_WILL_FREE))) {
__iget(inode);
- else
+ } else {
/*
* Handle the case where s_op->clear_inode is not been
* called yet, and somebody is calling igrab
* while the inode is getting freed.
*/
- inode = NULL;
+ ret = NULL;
+ }
+ spin_unlock(&inode->i_lock);
spin_unlock(&inode_lock);
- return inode;
+
+ return ret;
}
EXPORT_SYMBOL(igrab);

@@ -910,6 +947,7 @@ static struct inode *ifind(struct super_block *sb,
inode = find_inode(sb, head, test, data);
if (inode) {
__iget(inode);
+ spin_unlock(&inode->i_lock);
spin_unlock(&inode_lock);
if (likely(wait))
wait_on_inode(inode);
@@ -943,6 +981,7 @@ static struct inode *ifind_fast(struct super_block *sb,
inode = find_inode_fast(sb, head, ino);
if (inode) {
__iget(inode);
+ spin_unlock(&inode->i_lock);
spin_unlock(&inode_lock);
wait_on_inode(inode);
return inode;
@@ -1112,6 +1151,7 @@ int insert_inode_locked(struct inode *inode)
struct inode *old = NULL;

spin_lock(&inode_lock);
+repeat:
spin_lock(&inode_hash_lock);
hlist_for_each_entry(old, node, head, i_hash) {
if (old->i_ino != ino)
@@ -1120,6 +1160,10 @@ int insert_inode_locked(struct inode *inode)
continue;
if (old->i_state & (I_FREEING|I_WILL_FREE))
continue;
+ if (!spin_trylock(&old->i_lock)) {
+ spin_unlock(&inode_hash_lock);
+ goto repeat;
+ }
break;
}
if (likely(!node)) {
@@ -1130,6 +1174,7 @@ int insert_inode_locked(struct inode *inode)
}
spin_unlock(&inode_hash_lock);
__iget(old);
+ spin_unlock(&old->i_lock);
spin_unlock(&inode_lock);
wait_on_inode(old);
if (unlikely(!hlist_unhashed(&old->i_hash))) {
@@ -1154,6 +1199,7 @@ int insert_inode_locked4(struct inode *inode, unsigned long hashval,
struct inode *old = NULL;

spin_lock(&inode_lock);
+repeat:
spin_lock(&inode_hash_lock);
hlist_for_each_entry(old, node, head, i_hash) {
if (old->i_sb != sb)
@@ -1162,6 +1208,10 @@ int insert_inode_locked4(struct inode *inode, unsigned long hashval,
continue;
if (old->i_state & (I_FREEING|I_WILL_FREE))
continue;
+ if (!spin_trylock(&old->i_lock)) {
+ spin_unlock(&inode_hash_lock);
+ goto repeat;
+ }
break;
}
if (likely(!node)) {
@@ -1172,6 +1222,7 @@ int insert_inode_locked4(struct inode *inode, unsigned long hashval,
}
spin_unlock(&inode_hash_lock);
__iget(old);
+ spin_unlock(&old->i_lock);
spin_unlock(&inode_lock);
wait_on_inode(old);
if (unlikely(!hlist_unhashed(&old->i_hash))) {
@@ -1256,19 +1307,27 @@ static void iput_final(struct inode *inode)
else
drop = generic_drop_inode(inode);

+ spin_lock(&sb_inode_list_lock);
+ spin_lock(&inode->i_lock);
if (!drop) {
if (!(inode->i_state & (I_DIRTY|I_SYNC)))
list_move(&inode->i_list, &inode_unused);
inodes_stat.nr_unused++;
if (sb->s_flags & MS_ACTIVE) {
+ spin_unlock(&inode->i_lock);
+ spin_unlock(&sb_inode_list_lock);
spin_unlock(&inode_lock);
return;
}
WARN_ON(inode->i_state & I_NEW);
inode->i_state |= I_WILL_FREE;
+ spin_unlock(&inode->i_lock);
+ spin_unlock(&sb_inode_list_lock);
spin_unlock(&inode_lock);
write_inode_now(inode, 1);
spin_lock(&inode_lock);
+ spin_lock(&sb_inode_list_lock);
+ spin_lock(&inode->i_lock);
WARN_ON(inode->i_state & I_NEW);
inode->i_state &= ~I_WILL_FREE;
inodes_stat.nr_unused--;
@@ -1277,12 +1336,12 @@ static void iput_final(struct inode *inode)
spin_unlock(&inode_hash_lock);
}
list_del_init(&inode->i_list);
- spin_lock(&sb_inode_list_lock);
list_del_init(&inode->i_sb_list);
spin_unlock(&sb_inode_list_lock);
WARN_ON(inode->i_state & I_NEW);
inode->i_state |= I_FREEING;
inodes_stat.nr_inodes--;
+ spin_unlock(&inode->i_lock);
spin_unlock(&inode_lock);
evict(inode);
spin_lock(&inode_lock);
@@ -1491,6 +1550,8 @@ EXPORT_SYMBOL(inode_wait);
* wake_up_inode() after removing from the hash list will DTRT.
*
* This is called with inode_lock held.
+ *
+ * Called with i_lock held and returns with it dropped.
*/
static void __wait_on_freeing_inode(struct inode *inode)
{
@@ -1498,6 +1559,7 @@ static void __wait_on_freeing_inode(struct inode *inode)
DEFINE_WAIT_BIT(wait, &inode->i_state, __I_NEW);
wq = bit_waitqueue(&inode->i_state, __I_NEW);
prepare_to_wait(wq, &wait.wait, TASK_UNINTERRUPTIBLE);
+ spin_unlock(&inode->i_lock);
spin_unlock(&inode_lock);
schedule();
finish_wait(wq, &wait.wait);
diff --git a/fs/nilfs2/gcdat.c b/fs/nilfs2/gcdat.c
index 84a45d1..c51f0e8 100644
--- a/fs/nilfs2/gcdat.c
+++ b/fs/nilfs2/gcdat.c
@@ -27,6 +27,7 @@
#include "page.h"
#include "mdt.h"

+/* XXX: what protects i_state? */
int nilfs_init_gcdat_inode(struct the_nilfs *nilfs)
{
struct inode *dat = nilfs->ns_dat, *gcdat = nilfs->ns_gc_dat;
diff --git a/fs/quota/dquot.c b/fs/quota/dquot.c
index 2e3b913..15f66f1 100644
--- a/fs/quota/dquot.c
+++ b/fs/quota/dquot.c
@@ -899,18 +899,20 @@ static void add_dquot_ref(struct super_block *sb, int type)
spin_lock(&inode_lock);
spin_lock(&sb_inode_list_lock);
list_for_each_entry(inode, &sb->s_inodes, i_sb_list) {
- if (inode->i_state & (I_FREEING|I_WILL_FREE|I_NEW))
+ spin_lock(&inode->i_lock);
+ if ((inode->i_state & (I_FREEING|I_WILL_FREE|I_NEW) ||
+ !atomic_read(&inode->i_writecount) ||
+ !dqinit_needed(inode, type))) {
+ spin_unlock(&inode->i_lock);
continue;
+ }
#ifdef CONFIG_QUOTA_DEBUG
if (unlikely(inode_get_rsv_space(inode) > 0))
reserved = 1;
#endif
- if (!atomic_read(&inode->i_writecount))
- continue;
- if (!dqinit_needed(inode, type))
- continue;

__iget(inode);
+ spin_unlock(&inode->i_lock);
spin_unlock(&sb_inode_list_lock);
spin_unlock(&inode_lock);

--
1.7.1


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