[patch 13/35] fs: icache remove inode_lock

From: npiggin
Date: Tue Oct 19 2010 - 00:00:45 EST

Remove the global inode_lock, it has been made redundant by the
previous lock breakup.

Signed-off-by: Nick Piggin <npiggin@xxxxxxxxx>

---
Documentation/filesystems/Locking | 2
Documentation/filesystems/porting | 10 +++-
Documentation/filesystems/vfs.txt | 2
fs/buffer.c | 2
fs/drop_caches.c | 4 -
fs/fs-writeback.c | 47 ++++--------------
fs/inode.c | 95 +++++++-------------------------------
fs/notify/inode_mark.c | 11 +---
fs/ntfs/inode.c | 4 -
fs/ocfs2/inode.c | 2
fs/quota/dquot.c | 16 ++----
include/linux/fs.h | 2
include/linux/writeback.h | 1
mm/backing-dev.c | 4 -
mm/filemap.c | 6 +-
mm/rmap.c | 6 +-
16 files changed, 60 insertions(+), 154 deletions(-)

Index: linux-2.6/fs/buffer.c
===================================================================
--- linux-2.6.orig/fs/buffer.c 2010-10-19 14:17:23.000000000 +1100
+++ linux-2.6/fs/buffer.c 2010-10-19 14:18:59.000000000 +1100
@@ -1145,7 +1145,7 @@
* inode list.
*
* mark_buffer_dirty() is atomic. It takes bh->b_page->mapping->private_lock,
- * mapping->tree_lock and the global inode_lock.
+ * and mapping->tree_lock.
*/
void mark_buffer_dirty(struct buffer_head *bh)
{
Index: linux-2.6/fs/drop_caches.c
===================================================================
--- linux-2.6.orig/fs/drop_caches.c 2010-10-19 14:18:58.000000000 +1100
+++ linux-2.6/fs/drop_caches.c 2010-10-19 14:19:25.000000000 +1100
@@ -16,7 +16,6 @@
{
struct inode *inode, *toput_inode = NULL;

- spin_lock(&inode_lock);
spin_lock(&sb_inode_list_lock);
list_for_each_entry(inode, &sb->s_inodes, i_sb_list) {
spin_lock(&inode->i_lock);
@@ -28,15 +27,12 @@
__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);
iput(toput_inode);
toput_inode = inode;
- spin_lock(&inode_lock);
spin_lock(&sb_inode_list_lock);
}
spin_unlock(&sb_inode_list_lock);
- spin_unlock(&inode_lock);
iput(toput_inode);
}

Index: linux-2.6/fs/fs-writeback.c
===================================================================
--- linux-2.6.orig/fs/fs-writeback.c 2010-10-19 14:18:59.000000000 +1100
+++ linux-2.6/fs/fs-writeback.c 2010-10-19 14:19:31.000000000 +1100
@@ -194,7 +194,7 @@
static void inode_sync_complete(struct inode *inode)
{
/*
- * Prevent speculative execution through spin_unlock(&inode_lock);
+ * Prevent speculative execution through spin_unlock(&inode->i_lock);
*/
smp_mb();
wake_up_bit(&inode->i_state, __I_SYNC);
@@ -294,18 +294,16 @@
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);
}
}

/*
- * Write out an inode's dirty pages. Called under inode_lock. Either the
- * caller has ref on the inode (either via __iget or via syscall against an fd)
- * or the inode has I_WILL_FREE set (via generic_forget_inode)
+ * Write out an inode's dirty pages. Either the caller has ref on the inode
+ * (either via __iget or via syscall against an fd) or the inode has
+ * I_WILL_FREE set (via generic_forget_inode)
*
* If `wait' is set, wait on the writeout.
*
@@ -313,7 +311,8 @@
* starvation of particular inodes when others are being redirtied, prevent
* livelocks, etc.
*
- * Called under inode_lock.
+ * Called under wb_inode_list_lock and i_lock. May drop the locks but returns
+ * with them locked.
*/
static int
writeback_single_inode(struct inode *inode, struct writeback_control *wbc)
@@ -354,7 +353,6 @@
inode->i_state &= ~I_DIRTY_PAGES;
spin_unlock(&wb_inode_list_lock);
spin_unlock(&inode->i_lock);
- spin_unlock(&inode_lock);

ret = do_writepages(mapping, wbc);

@@ -374,12 +372,10 @@
* due to delalloc, clear dirty metadata flags right before
* 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)) {
int err = write_inode(inode, wbc);
@@ -387,7 +383,6 @@
ret = err;
}

- spin_lock(&inode_lock);
spin_lock(&inode->i_lock);
spin_lock(&wb_inode_list_lock);
inode->i_state &= ~I_SYNC;
@@ -537,10 +532,8 @@
}
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;
@@ -560,7 +553,6 @@

if (!wbc->wb_start)
wbc->wb_start = jiffies; /* livelock avoidance */
- spin_lock(&inode_lock);
again:
spin_lock(&wb_inode_list_lock);

@@ -588,7 +580,6 @@
break;
}
spin_unlock(&wb_inode_list_lock);
- spin_unlock(&inode_lock);
/* Leave any unwritten inodes on b_io */
}

@@ -597,13 +588,11 @@
{
WARN_ON(!rwsem_is_locked(&sb->s_umount));

- spin_lock(&inode_lock);
spin_lock(&wb_inode_list_lock);
if (!wbc->for_kupdate || list_empty(&wb->b_io))
queue_io(wb, wbc->older_than_this);
writeback_sb_inodes(sb, wb, wbc, true);
spin_unlock(&wb_inode_list_lock);
- spin_unlock(&inode_lock);
}

/*
@@ -714,14 +703,12 @@
* 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;
}
trace_wbc_writeback_wait(&wbc, wb->bdi);
@@ -729,7 +716,6 @@
spin_unlock(&inode->i_lock);
}
spin_unlock(&wb_inode_list_lock);
- spin_unlock(&inode_lock);
}

return wrote;
@@ -993,7 +979,6 @@
if (unlikely(block_dump))
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;
@@ -1048,7 +1033,6 @@
}
out:
spin_unlock(&inode->i_lock);
- spin_unlock(&inode_lock);

if (wakeup_bdi)
bdi_wakeup_thread_delayed(bdi);
@@ -1082,7 +1066,6 @@
*/
WARN_ON(!rwsem_is_locked(&sb->s_umount));

- spin_lock(&inode_lock);
spin_lock(&sb_inode_list_lock);

/*
@@ -1110,14 +1093,12 @@
__iget(inode);
spin_unlock(&inode->i_lock);
spin_unlock(&sb_inode_list_lock);
- spin_unlock(&inode_lock);
/*
- * We hold a reference to 'inode' so it couldn't have
- * been removed from s_inodes list while we dropped the
- * inode_lock. We cannot iput the inode now as we can
- * be holding the last reference and we cannot iput it
- * under inode_lock. So we keep the reference and iput
- * it later.
+ * We hold a reference to 'inode' so it couldn't have been
+ * removed from s_inodes list while we dropped the
+ * sb_inode_list_lock. We cannot iput the inode now as we can
+ * be holding the last reference and we cannot iput it under
+ * spinlock. So we keep the reference and iput it later.
*/
iput(old_inode);
old_inode = inode;
@@ -1126,11 +1107,9 @@

cond_resched();

- spin_lock(&inode_lock);
spin_lock(&sb_inode_list_lock);
}
spin_unlock(&sb_inode_list_lock);
- spin_unlock(&inode_lock);
iput(old_inode);
}

@@ -1235,13 +1214,11 @@
wbc.nr_to_write = 0;

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)
inode_sync_wait(inode);
return ret;
@@ -1263,13 +1240,11 @@
{
int ret;

- 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;
}
EXPORT_SYMBOL(sync_inode);
Index: linux-2.6/fs/inode.c
===================================================================
--- linux-2.6.orig/fs/inode.c 2010-10-19 14:18:59.000000000 +1100
+++ linux-2.6/fs/inode.c 2010-10-19 14:19:31.000000000 +1100
@@ -41,11 +41,10 @@
* i_sb_list
*
* Ordering:
- * inode_lock
- * sb_inode_list_lock
- * inode->i_lock
- * wb_inode_list_lock
- * inode_hash_lock
+ * sb_inode_list_lock
+ * inode->i_lock
+ * wb_inode_list_lock
+ * inode_hash_lock
*/
/*
* This is needed for the following functions:
@@ -104,7 +103,6 @@
* NOTE! You also have to own the lock if you change
* the i_state of an inode while it is in use..
*/
-DEFINE_SPINLOCK(inode_lock);
DEFINE_SPINLOCK(sb_inode_list_lock);
DEFINE_SPINLOCK(wb_inode_list_lock);
static DEFINE_SPINLOCK(inode_hash_lock);
@@ -136,7 +134,7 @@
static void wake_up_inode(struct inode *inode)
{
/*
- * Prevent speculative execution through spin_unlock(&inode_lock);
+ * Prevent speculative execution through spin_unlock(&inode->i_lock);
*/
smp_mb();
wake_up_bit(&inode->i_state, __I_NEW);
@@ -308,7 +306,7 @@
}

/*
- * inode_lock must be held
+ * i_lock must be held
*/
void __iget(struct inode *inode)
{
@@ -372,16 +370,14 @@

evict(inode);

- spin_lock(&inode_lock);
spin_lock(&sb_inode_list_lock);
spin_lock(&inode->i_lock);
spin_lock(&inode_hash_lock);
hlist_del_init(&inode->i_hash);
spin_unlock(&inode_hash_lock);
list_del_init(&inode->i_sb_list);
- spin_unlock(&sb_inode_list_lock);
spin_unlock(&inode->i_lock);
- spin_unlock(&inode_lock);
+ spin_unlock(&sb_inode_list_lock);

wake_up_inode(inode);
destroy_inode(inode);
@@ -407,7 +403,6 @@
* change during umount anymore, and because iprune_sem keeps
* shrink_icache_memory() away.
*/
- cond_resched_lock(&inode_lock);
cond_resched_lock(&sb_inode_list_lock);

next = next->next;
@@ -452,12 +447,10 @@
LIST_HEAD(throw_away);

down_write(&iprune_sem);
- spin_lock(&inode_lock);
spin_lock(&sb_inode_list_lock);
fsnotify_unmount_inodes(&sb->s_inodes);
busy = invalidate_list(&sb->s_inodes, &throw_away);
spin_unlock(&sb_inode_list_lock);
- spin_unlock(&inode_lock);

dispose_list(&throw_away);
up_write(&iprune_sem);
@@ -481,7 +474,7 @@

/*
* Scan `goal' inodes on the unused list for freeable ones. They are moved to
- * a temporary list and then are freed outside inode_lock by dispose_list().
+ * a temporary list and then are freed outside LRU lock by dispose_list().
*
* Any inodes which are pinned purely because of attached pagecache have their
* pagecache removed. We expect the final iput() on that inode to add it to
@@ -500,7 +493,6 @@
unsigned long reap = 0;

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++) {
@@ -524,12 +516,10 @@
spin_unlock(&wb_inode_list_lock);
__iget(inode);
spin_unlock(&inode->i_lock);
- spin_unlock(&inode_lock);
if (remove_inode_buffers(inode))
reap += invalidate_mapping_pages(&inode->i_data,
0, -1);
iput(inode);
- spin_lock(&inode_lock);
again2:
spin_lock(&wb_inode_list_lock);

@@ -556,7 +546,6 @@
__count_vm_events(KSWAPD_INODESTEAL, reap);
else
__count_vm_events(PGINODESTEAL, reap);
- spin_unlock(&inode_lock);
spin_unlock(&wb_inode_list_lock);

dispose_list(&freeable);
@@ -704,9 +693,9 @@
* @inode: inode to mark in use
*
* When an inode is allocated it needs to be accounted for, added to the in use
- * list, the owning superblock and the inode hash. This needs to be done under
- * the inode_lock, so export a function to do this rather than the inode lock
- * itself. We calculate the hash list to add to here so it is all internal
+ * list, the owning superblock and the inode hash.
+ *
+ * We calculate the hash list to add to here so it is all internal
* which requires the caller to have already set up the inode number in the
* inode to add.
*/
@@ -714,12 +703,10 @@
{
struct hlist_head *head = inode_hashtable + hash(sb, inode->i_ino);

- spin_lock(&inode_lock);
spin_lock(&sb_inode_list_lock);
spin_lock(&inode->i_lock);
__inode_add_to_lists(sb, head, inode);
spin_unlock(&inode->i_lock);
- spin_unlock(&inode_lock);
}
EXPORT_SYMBOL_GPL(inode_add_to_lists);

@@ -745,18 +732,14 @@
static atomic_t last_ino = ATOMIC_INIT(0);
struct inode *inode;

- spin_lock_prefetch(&inode_lock);
-
inode = alloc_inode(sb);
if (inode) {
- spin_lock(&inode_lock);
spin_lock(&sb_inode_list_lock);
spin_lock(&inode->i_lock);
inode->i_ino = (unsigned int)atomic_inc_return(&last_ino);
inode->i_state = 0;
__inode_add_to_lists(sb, NULL, inode);
spin_unlock(&inode->i_lock);
- spin_unlock(&inode_lock);
}
return inode;
}
@@ -815,7 +798,6 @@
if (inode) {
struct inode *old;

- spin_lock(&inode_lock);
/* We released the lock, so.. */
old = find_inode(sb, head, test, data);
if (!old) {
@@ -827,7 +809,6 @@
inode->i_state = I_NEW;
__inode_add_to_lists(sb, head, inode);
spin_unlock(&inode->i_lock);
- spin_unlock(&inode_lock);

/* Return the locked inode with I_NEW set, the
* caller is responsible for filling in the contents
@@ -842,7 +823,6 @@
*/
__iget(old);
spin_unlock(&old->i_lock);
- spin_unlock(&inode_lock);
destroy_inode(inode);
inode = old;
wait_on_inode(inode);
@@ -852,7 +832,6 @@
set_failed:
spin_unlock(&inode->i_lock);
spin_unlock(&sb_inode_list_lock);
- spin_unlock(&inode_lock);
destroy_inode(inode);
return NULL;
}
@@ -870,7 +849,6 @@
if (inode) {
struct inode *old;

- spin_lock(&inode_lock);
/* We released the lock, so.. */
old = find_inode_fast(sb, head, ino);
if (!old) {
@@ -880,7 +858,6 @@
inode->i_state = I_NEW;
__inode_add_to_lists(sb, head, inode);
spin_unlock(&inode->i_lock);
- spin_unlock(&inode_lock);

/* Return the locked inode with I_NEW set, the
* caller is responsible for filling in the contents
@@ -895,7 +872,6 @@
*/
__iget(old);
spin_unlock(&old->i_lock);
- spin_unlock(&inode_lock);
destroy_inode(inode);
inode = old;
wait_on_inode(inode);
@@ -951,7 +927,6 @@
static unsigned int counter;
ino_t res;

- spin_lock(&inode_lock);
spin_lock(&unique_lock);
do {
if (counter <= max_reserved)
@@ -959,7 +934,6 @@
res = counter++;
} while (!is_ino_hashed(sb, res));
spin_unlock(&unique_lock);
- spin_unlock(&inode_lock);

return res;
}
@@ -969,7 +943,6 @@
{
struct inode *ret = inode;

- spin_lock(&inode_lock);
spin_lock(&inode->i_lock);
if (!(inode->i_state & (I_FREEING|I_WILL_FREE)))
__iget(inode);
@@ -981,7 +954,6 @@
*/
ret = NULL;
spin_unlock(&inode->i_lock);
- spin_unlock(&inode_lock);

return ret;
}
@@ -1004,7 +976,7 @@
*
* Otherwise NULL is returned.
*
- * Note, @test is called with the inode_lock held, so can't sleep.
+ * Note, @test is called with the i_lock held, so can't sleep.
*/
static struct inode *ifind(struct super_block *sb,
struct hlist_head *head, int (*test)(struct inode *, void *),
@@ -1012,17 +984,14 @@
{
struct inode *inode;

- spin_lock(&inode_lock);
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);
return inode;
}
- spin_unlock(&inode_lock);
return NULL;
}

@@ -1046,16 +1015,13 @@
{
struct inode *inode;

- spin_lock(&inode_lock);
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;
}
- spin_unlock(&inode_lock);
return NULL;
}

@@ -1078,7 +1044,7 @@
*
* Otherwise NULL is returned.
*
- * Note, @test is called with the inode_lock held, so can't sleep.
+ * Note, @test is called with the i_lock held, so can't sleep.
*/
struct inode *ilookup5_nowait(struct super_block *sb, unsigned long hashval,
int (*test)(struct inode *, void *), void *data)
@@ -1106,7 +1072,7 @@
*
* Otherwise NULL is returned.
*
- * Note, @test is called with the inode_lock held, so can't sleep.
+ * Note, @test is called with the i_lock held, so can't sleep.
*/
struct inode *ilookup5(struct super_block *sb, unsigned long hashval,
int (*test)(struct inode *, void *), void *data)
@@ -1157,7 +1123,7 @@
* inode and this is returned locked, hashed, and with the I_NEW flag set. The
* file system gets to fill it in before unlocking it via unlock_new_inode().
*
- * Note both @test and @set are called with the inode_lock held, so can't sleep.
+ * Note both @test and @set are called with the i_lock held, so can't sleep.
*/
struct inode *iget5_locked(struct super_block *sb, unsigned long hashval,
int (*test)(struct inode *, void *),
@@ -1219,7 +1185,6 @@
struct hlist_node *node;
struct inode *old = NULL;

- spin_lock(&inode_lock);
repeat:
spin_lock(&inode_hash_lock);
hlist_for_each_entry(old, node, head, i_hash) {
@@ -1238,13 +1203,11 @@
if (likely(!node)) {
hlist_add_head(&inode->i_hash, head);
spin_unlock(&inode_hash_lock);
- spin_unlock(&inode_lock);
return 0;
}
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))) {
iput(old);
@@ -1267,7 +1230,6 @@
struct hlist_node *node;
struct inode *old = NULL;

- spin_lock(&inode_lock);
repeat:
spin_lock(&inode_hash_lock);
hlist_for_each_entry(old, node, head, i_hash) {
@@ -1286,13 +1248,11 @@
if (likely(!node)) {
hlist_add_head(&inode->i_hash, head);
spin_unlock(&inode_hash_lock);
- spin_unlock(&inode_lock);
return 0;
}
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))) {
iput(old);
@@ -1315,13 +1275,11 @@
{
struct hlist_head *head = inode_hashtable + hash(inode->i_sb, hashval);

- spin_lock(&inode_lock);
spin_lock(&inode->i_lock);
spin_lock(&inode_hash_lock);
hlist_add_head(&inode->i_hash, head);
spin_unlock(&inode_hash_lock);
spin_unlock(&inode->i_lock);
- spin_unlock(&inode_lock);
}
EXPORT_SYMBOL(__insert_inode_hash);

@@ -1333,13 +1291,11 @@
*/
void remove_inode_hash(struct inode *inode)
{
- spin_lock(&inode_lock);
spin_lock(&inode->i_lock);
spin_lock(&inode_hash_lock);
hlist_del_init(&inode->i_hash);
spin_unlock(&inode_hash_lock);
spin_unlock(&inode->i_lock);
- spin_unlock(&inode_lock);
}
EXPORT_SYMBOL(remove_inode_hash);

@@ -1391,16 +1347,13 @@
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);
@@ -1418,15 +1371,12 @@
WARN_ON(inode->i_state & I_NEW);
inode->i_state |= I_FREEING;
spin_unlock(&inode->i_lock);
- spin_unlock(&inode_lock);
evict(inode);
- spin_lock(&inode_lock);
spin_lock(&inode->i_lock);
spin_lock(&inode_hash_lock);
hlist_del_init(&inode->i_hash);
spin_unlock(&inode_hash_lock);
spin_unlock(&inode->i_lock);
- spin_unlock(&inode_lock);
wake_up_inode(inode);
BUG_ON(inode->i_state != (I_FREEING | I_CLEAR));
destroy_inode(inode);
@@ -1446,17 +1396,12 @@
if (inode) {
BUG_ON(inode->i_state & I_CLEAR);

-retry1:
+retry:
spin_lock(&inode->i_lock);
if (inode->i_count == 1) {
- if (!spin_trylock(&inode_lock)) {
-retry2:
- spin_unlock(&inode->i_lock);
- goto retry1;
- }
if (!spin_trylock(&sb_inode_list_lock)) {
- spin_unlock(&inode_lock);
- goto retry2;
+ spin_unlock(&inode->i_lock);
+ goto retry;
}
inode->i_count--;
iput_final(inode);
@@ -1643,8 +1588,6 @@
* It doesn't matter if I_NEW is not set initially, a call to
* 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)
@@ -1654,10 +1597,8 @@
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);
- spin_lock(&inode_lock);
}

static __initdata unsigned long ihash_entries;
Index: linux-2.6/include/linux/writeback.h
===================================================================
--- linux-2.6.orig/include/linux/writeback.h 2010-10-19 14:18:58.000000000 +1100
+++ linux-2.6/include/linux/writeback.h 2010-10-19 14:19:30.000000000 +1100
@@ -9,7 +9,6 @@

struct backing_dev_info;

-extern spinlock_t inode_lock;
extern spinlock_t sb_inode_list_lock;
extern spinlock_t wb_inode_list_lock;
extern struct list_head inode_in_use;
Index: linux-2.6/fs/quota/dquot.c
===================================================================
--- linux-2.6.orig/fs/quota/dquot.c 2010-10-19 14:18:58.000000000 +1100
+++ linux-2.6/fs/quota/dquot.c 2010-10-19 14:19:25.000000000 +1100
@@ -76,7 +76,7 @@
#include <linux/buffer_head.h>
#include <linux/capability.h>
#include <linux/quotaops.h>
-#include <linux/writeback.h> /* for inode_lock, oddly enough.. */
+#include <linux/writeback.h>

#include <asm/uaccess.h>

@@ -897,7 +897,6 @@
int reserved = 0;
#endif

- spin_lock(&inode_lock);
spin_lock(&sb_inode_list_lock);
list_for_each_entry(inode, &sb->s_inodes, i_sb_list) {
spin_lock(&inode->i_lock);
@@ -921,21 +920,18 @@
__iget(inode);
spin_unlock(&inode->i_lock);
spin_unlock(&sb_inode_list_lock);
- spin_unlock(&inode_lock);

iput(old_inode);
__dquot_initialize(inode, type);
/* We hold a reference to 'inode' so it couldn't have been
- * removed from s_inodes list while we dropped the inode_lock.
- * We cannot iput the inode now as we can be holding the last
- * reference and we cannot iput it under inode_lock. So we
- * keep the reference and iput it later. */
+ * removed from s_inodes list while we dropped the
+ * sb_inode_list_lock. We cannot iput the inode now as we can
+ * be holding the last reference and we cannot iput it under
+ * lock. So we keep the reference and iput it later. */
old_inode = inode;
- spin_lock(&inode_lock);
spin_lock(&sb_inode_list_lock);
}
spin_unlock(&sb_inode_list_lock);
- spin_unlock(&inode_lock);
iput(old_inode);

#ifdef CONFIG_QUOTA_DEBUG
@@ -1016,7 +1012,6 @@
struct inode *inode;
int reserved = 0;

- spin_lock(&inode_lock);
spin_lock(&sb_inode_list_lock);
list_for_each_entry(inode, &sb->s_inodes, i_sb_list) {
/*
@@ -1032,7 +1027,6 @@
}
}
spin_unlock(&sb_inode_list_lock);
- spin_unlock(&inode_lock);
#ifdef CONFIG_QUOTA_DEBUG
if (reserved) {
printk(KERN_WARNING "VFS (%s): Writes happened after quota"
Index: linux-2.6/fs/notify/inode_mark.c
===================================================================
--- linux-2.6.orig/fs/notify/inode_mark.c 2010-10-19 14:18:58.000000000 +1100
+++ linux-2.6/fs/notify/inode_mark.c 2010-10-19 14:19:25.000000000 +1100
@@ -22,7 +22,7 @@
#include <linux/module.h>
#include <linux/mutex.h>
#include <linux/spinlock.h>
-#include <linux/writeback.h> /* for inode_lock */
+#include <linux/writeback.h>

#include <asm/atomic.h>

@@ -232,9 +232,8 @@
* fsnotify_unmount_inodes - an sb is unmounting. handle any watched inodes.
* @list: list of inodes being unmounted (sb->s_inodes)
*
- * Called with inode_lock held, protecting the unmounting super block's list
- * of inodes, and with iprune_mutex held, keeping shrink_icache_memory() at bay.
- * We temporarily drop inode_lock, however, and CAN block.
+ * Called with iprune_mutex held, keeping shrink_icache_memory() at bay.
+ * sb_inode_list_lock to protect the super block's list of inodes.
*/
void fsnotify_unmount_inodes(struct list_head *list)
{
@@ -287,13 +286,12 @@
}

/*
- * We can safely drop inode_lock here because we hold
+ * We can safely drop sb_inode_list_lock here because we hold
* references on both inode and next_i. Also no new inodes
* will be added since the umount has begun. Finally,
* iprune_mutex keeps shrink_icache_memory() away.
*/
spin_unlock(&sb_inode_list_lock);
- spin_unlock(&inode_lock);

if (need_iput_tmp)
iput(need_iput_tmp);
@@ -305,7 +303,6 @@

iput(inode);

- spin_lock(&inode_lock);
spin_lock(&sb_inode_list_lock);
}
}
Index: linux-2.6/mm/backing-dev.c
===================================================================
--- linux-2.6.orig/mm/backing-dev.c 2010-10-19 14:18:58.000000000 +1100
+++ linux-2.6/mm/backing-dev.c 2010-10-19 14:19:21.000000000 +1100
@@ -73,7 +73,6 @@
struct inode *inode;

nr_wb = nr_dirty = nr_io = nr_more_io = 0;
- spin_lock(&inode_lock);
spin_lock(&wb_inode_list_lock);
list_for_each_entry(inode, &wb->b_dirty, i_list)
nr_dirty++;
@@ -82,7 +81,6 @@
list_for_each_entry(inode, &wb->b_more_io, i_list)
nr_more_io++;
spin_unlock(&wb_inode_list_lock);
- spin_unlock(&inode_lock);

global_dirty_limits(&background_thresh, &dirty_thresh);
bdi_thresh = bdi_dirty_limit(bdi, dirty_thresh);
@@ -684,13 +682,11 @@
if (bdi_has_dirty_io(bdi)) {
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);
}

bdi_unregister(bdi);
Index: linux-2.6/mm/filemap.c
===================================================================
--- linux-2.6.orig/mm/filemap.c 2010-10-19 14:17:28.000000000 +1100
+++ linux-2.6/mm/filemap.c 2010-10-19 14:18:59.000000000 +1100
@@ -80,7 +80,7 @@
* ->i_mutex
* ->i_alloc_sem (various)
*
- * ->inode_lock
+ * ->i_lock
* ->sb_lock (fs/fs-writeback.c)
* ->mapping->tree_lock (__sync_single_inode)
*
@@ -98,8 +98,8 @@
* ->zone.lru_lock (check_pte_range->isolate_lru_page)
* ->private_lock (page_remove_rmap->set_page_dirty)
* ->tree_lock (page_remove_rmap->set_page_dirty)
- * ->inode_lock (page_remove_rmap->set_page_dirty)
- * ->inode_lock (zap_pte_range->set_page_dirty)
+ * ->i_lock (page_remove_rmap->set_page_dirty)
+ * ->i_lock (zap_pte_range->set_page_dirty)
* ->private_lock (zap_pte_range->__set_page_dirty_buffers)
*
* ->task->proc_lock
Index: linux-2.6/mm/rmap.c
===================================================================
--- linux-2.6.orig/mm/rmap.c 2010-10-19 14:17:23.000000000 +1100
+++ linux-2.6/mm/rmap.c 2010-10-19 14:18:59.000000000 +1100
@@ -31,11 +31,11 @@
* swap_lock (in swap_duplicate, swap_info_get)
* mmlist_lock (in mmput, drain_mmlist and others)
* mapping->private_lock (in __set_page_dirty_buffers)
- * inode_lock (in set_page_dirty's __mark_inode_dirty)
- * sb_lock (within inode_lock in fs/fs-writeback.c)
+ * i_lock (in set_page_dirty's __mark_inode_dirty)
+ * sb_lock (within i_lock in fs/fs-writeback.c)
* mapping->tree_lock (widely used, in set_page_dirty,
* in arch-dependent flush_dcache_mmap_lock,
- * within inode_lock in __sync_single_inode)
+ * within i_lock in __sync_single_inode)
*
* (code doesn't rely on that order so it could be switched around)
* ->tasklist_lock
Index: linux-2.6/Documentation/filesystems/Locking
===================================================================
--- linux-2.6.orig/Documentation/filesystems/Locking 2010-10-19 14:17:22.000000000 +1100
+++ linux-2.6/Documentation/filesystems/Locking 2010-10-19 14:19:25.000000000 +1100
@@ -114,7 +114,7 @@
destroy_inode:
dirty_inode: (must not sleep)
write_inode:
-drop_inode: !!!inode_lock!!!
+drop_inode: !!!i_lock, sb_inode_list_lock!!!
evict_inode:
put_super: write
write_super: read
Index: linux-2.6/Documentation/filesystems/vfs.txt
===================================================================
--- linux-2.6.orig/Documentation/filesystems/vfs.txt 2010-10-19 14:17:22.000000000 +1100
+++ linux-2.6/Documentation/filesystems/vfs.txt 2010-10-19 14:19:25.000000000 +1100
@@ -246,7 +246,7 @@
should be synchronous or not, not all filesystems check this flag.

drop_inode: called when the last access to the inode is dropped,
- with the inode_lock spinlock held.
+ with the i_lock and sb_inode_list_lock spinlock held.

This method should be either NULL (normal UNIX filesystem
semantics) or "generic_delete_inode" (for filesystems that do not
Index: linux-2.6/fs/ntfs/inode.c
===================================================================
--- linux-2.6.orig/fs/ntfs/inode.c 2010-10-19 14:17:23.000000000 +1100
+++ linux-2.6/fs/ntfs/inode.c 2010-10-19 14:19:28.000000000 +1100
@@ -54,7 +54,7 @@
*
* Return 1 if the attributes match and 0 if not.
*
- * NOTE: This function runs with the inode_lock spin lock held so it is not
+ * NOTE: This function runs with the i_lock spin lock held so it is not
* allowed to sleep.
*/
int ntfs_test_inode(struct inode *vi, ntfs_attr *na)
@@ -98,7 +98,7 @@
*
* Return 0 on success and -errno on error.
*
- * NOTE: This function runs with the inode_lock spin lock held so it is not
+ * NOTE: This function runs with the i_lock spin lock held so it is not
* allowed to sleep. (Hence the GFP_ATOMIC allocation.)
*/
static int ntfs_init_locked_inode(struct inode *vi, ntfs_attr *na)
Index: linux-2.6/fs/ocfs2/inode.c
===================================================================
--- linux-2.6.orig/fs/ocfs2/inode.c 2010-10-19 14:17:23.000000000 +1100
+++ linux-2.6/fs/ocfs2/inode.c 2010-10-19 14:18:59.000000000 +1100
@@ -1195,7 +1195,7 @@
ocfs2_clear_inode(inode);
}

-/* Called under inode_lock, with no more references on the
+/* Called under i_lock, with no more references on the
* struct inode, so it's safe here to check the flags field
* and to manipulate i_nlink without any other locks. */
int ocfs2_drop_inode(struct inode *inode)
Index: linux-2.6/include/linux/fs.h
===================================================================
--- linux-2.6.orig/include/linux/fs.h 2010-10-19 14:18:59.000000000 +1100
+++ linux-2.6/include/linux/fs.h 2010-10-19 14:19:31.000000000 +1100
@@ -1589,7 +1589,7 @@
};

/*
- * Inode state bits. Protected by inode_lock.
+ * Inode state bits. Protected by i_lock.
*
* Three bits determine the dirty state of the inode, I_DIRTY_SYNC,
* I_DIRTY_DATASYNC and I_DIRTY_PAGES.
Index: linux-2.6/Documentation/filesystems/porting
===================================================================
--- linux-2.6.orig/Documentation/filesystems/porting 2010-10-19 14:17:22.000000000 +1100
+++ linux-2.6/Documentation/filesystems/porting 2010-10-19 14:19:28.000000000 +1100
@@ -299,7 +299,7 @@
remaining links or not. Caller does *not* evict the pagecache or inode-associated
metadata buffers; getting rid of those is responsibility of method, as it had
been for ->delete_inode().
- ->drop_inode() returns int now; it's called on final iput() with inode_lock
+ ->drop_inode() returns int now; it's called on final iput() with i_lock
held and it returns true if filesystems wants the inode to be dropped. As before,
generic_drop_inode() is still the default and it's been updated appropriately.
generic_delete_inode() is also alive and it consists simply of return 1. Note that
@@ -318,3 +318,11 @@
may happen while the inode is in the middle of ->write_inode(); e.g. if you blindly
free the on-disk inode, you may end up doing that while ->write_inode() is writing
to it.
+
+--
+[mandatory]
+ inode_lock is gone, replaced by fine grained locks. See fs/inode.c
+for details of what locks to replace inode_lock with in order to protect
+particular things. Most of the time, a filesystem only needs ->i_lock, which
+protects *all* the inode state and its membership on lists that was
+previously protected with inode_lock.


--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at http://vger.kernel.org/majordomo-info.html
Please read the FAQ at http://www.tux.org/lkml/