[patch 8/9] mm: spinlock tree_lock

Nick Piggin
2007-04-12T12:46:10Z

mapping->tree_lock has no read lockers. convert the lock from an rwlock
to a spinlock.

Signed-off-by: Nick Piggin <npiggin@suse.de>

Index: linux-2.6/fs/buffer.c
===================================================================
--- linux-2.6.orig/fs/buffer.c
+++ linux-2.6/fs/buffer.c
@@ -729,7 +729,7 @@ int __set_page_dirty_buffers(struct page
if (TestSetPageDirty(page))
return 0;

- write_lock_irq(&mapping->tree_lock);
+ spin_lock_irq(&mapping->tree_lock);
if (page->mapping) { /* Race with truncate? */
if (mapping_cap_account_dirty(mapping)) {
__inc_zone_page_state(page, NR_FILE_DIRTY);
@@ -738,7 +738,7 @@ int __set_page_dirty_buffers(struct page
radix_tree_tag_set(&mapping->page_tree,
page_index(page), PAGECACHE_TAG_DIRTY);
}
- write_unlock_irq(&mapping->tree_lock);
+ spin_unlock_irq(&mapping->tree_lock);
__mark_inode_dirty(mapping->host, I_DIRTY_PAGES);
return 1;
}
Index: linux-2.6/fs/inode.c
===================================================================
--- linux-2.6.orig/fs/inode.c
+++ linux-2.6/fs/inode.c
@@ -193,7 +193,7 @@ void inode_init_once(struct inode *inode
mutex_init(&inode->i_mutex);
init_rwsem(&inode->i_alloc_sem);
INIT_RADIX_TREE(&inode->i_data.page_tree, GFP_ATOMIC);
- rwlock_init(&inode->i_data.tree_lock);
+ spin_lock_init(&inode->i_data.tree_lock);
spin_lock_init(&inode->i_data.i_mmap_lock);
INIT_LIST_HEAD(&inode->i_data.private_list);
spin_lock_init(&inode->i_data.private_lock);
Index: linux-2.6/include/linux/fs.h
===================================================================
--- linux-2.6.orig/include/linux/fs.h
+++ linux-2.6/include/linux/fs.h
@@ -434,7 +434,7 @@ struct backing_dev_info;
struct address_space {
struct inode *host; /* owner: inode, block_device */
struct radix_tree_root page_tree; /* radix tree of all pages */
- rwlock_t tree_lock; /* and rwlock protecting it */
+ spinlock_t tree_lock; /* and lock protecting it */
unsigned int i_mmap_writable;/* count VM_SHARED mappings */
struct prio_tree_root i_mmap; /* tree of private and shared mappings */
struct list_head i_mmap_nonlinear;/*list VM_NONLINEAR mappings */
Index: linux-2.6/mm/filemap.c
===================================================================
--- linux-2.6.orig/mm/filemap.c
+++ linux-2.6/mm/filemap.c
@@ -110,7 +110,7 @@ generic_file_direct_IO(int rw, struct ki
/*
* Remove a page from the page cache and free it. Caller has to make
* sure the page is locked and that nobody else uses it - or that usage
- * is safe. The caller must hold a write_lock on the mapping's tree_lock.
+ * is safe. The caller must hold the mapping's tree_lock.
*/
void __remove_from_page_cache(struct page *page)
{
@@ -128,9 +128,9 @@ void remove_from_page_cache(struct page

BUG_ON(!PageLocked(page));

- write_lock_irq(&mapping->tree_lock);
+ spin_lock_irq(&mapping->tree_lock);
__remove_from_page_cache(page);
- write_unlock_irq(&mapping->tree_lock);
+ spin_unlock_irq(&mapping->tree_lock);
}

static int sync_page(void *word)
@@ -441,7 +441,7 @@ int add_to_page_cache(struct page *page,

if (error == 0) {
set_page_nonewrefs(page);
- write_lock_irq(&mapping->tree_lock);
+ spin_lock_irq(&mapping->tree_lock);
error = radix_tree_insert(&mapping->page_tree, offset, page);
if (!error) {
page_cache_get(page);
@@ -451,7 +451,7 @@ int add_to_page_cache(struct page *page,
mapping->nrpages++;
__inc_zone_page_state(page, NR_FILE_PAGES);
}
- write_unlock_irq(&mapping->tree_lock);
+ spin_unlock_irq(&mapping->tree_lock);
clear_page_nonewrefs(page);
radix_tree_preload_end();
}
Index: linux-2.6/mm/swap_state.c
===================================================================
--- linux-2.6.orig/mm/swap_state.c
+++ linux-2.6/mm/swap_state.c
@@ -38,7 +38,7 @@ static struct backing_dev_info swap_back

struct address_space swapper_space = {
.page_tree = RADIX_TREE_INIT(GFP_ATOMIC|__GFP_NOWARN),
- .tree_lock = __RW_LOCK_UNLOCKED(swapper_space.tree_lock),
+ .tree_lock = __SPIN_LOCK_UNLOCKED(swapper_space.tree_lock),
.a_ops = &swap_aops,
.i_mmap_nonlinear = LIST_HEAD_INIT(swapper_space.i_mmap_nonlinear),
.backing_dev_info = &swap_backing_dev_info,
@@ -80,7 +80,7 @@ static int __add_to_swap_cache(struct pa
error = radix_tree_preload(gfp_mask);
if (!error) {
set_page_nonewrefs(page);
- write_lock_irq(&swapper_space.tree_lock);
+ spin_lock_irq(&swapper_space.tree_lock);
error = radix_tree_insert(&swapper_space.page_tree,
entry.val, page);
if (!error) {
@@ -90,7 +90,7 @@ static int __add_to_swap_cache(struct pa
total_swapcache_pages++;
__inc_zone_page_state(page, NR_FILE_PAGES);
}
- write_unlock_irq(&swapper_space.tree_lock);
+ spin_unlock_irq(&swapper_space.tree_lock);
clear_page_nonewrefs(page);
radix_tree_preload_end();
}
@@ -202,9 +202,9 @@ void delete_from_swap_cache(struct page

entry.val = page_private(page);

- write_lock_irq(&swapper_space.tree_lock);
+ spin_lock_irq(&swapper_space.tree_lock);
__delete_from_swap_cache(page);
- write_unlock_irq(&swapper_space.tree_lock);
+ spin_unlock_irq(&swapper_space.tree_lock);

swap_free(entry);
page_cache_release(page);
Index: linux-2.6/mm/swapfile.c
===================================================================
--- linux-2.6.orig/mm/swapfile.c
+++ linux-2.6/mm/swapfile.c
@@ -367,13 +367,13 @@ int remove_exclusive_swap_page(struct pa
retval = 0;
if (p->swap_map[swp_offset(entry)] == 1) {
/* Recheck the page count with the swapcache lock held.. */
- write_lock_irq(&swapper_space.tree_lock);
+ spin_lock_irq(&swapper_space.tree_lock);
if ((page_count(page) == 2) && !PageWriteback(page)) {
__delete_from_swap_cache(page);
SetPageDirty(page);
retval = 1;
}
- write_unlock_irq(&swapper_space.tree_lock);
+ spin_unlock_irq(&swapper_space.tree_lock);
}
spin_unlock(&swap_lock);

Index: linux-2.6/mm/truncate.c
===================================================================
--- linux-2.6.orig/mm/truncate.c
+++ linux-2.6/mm/truncate.c
@@ -328,18 +328,18 @@ invalidate_complete_page2(struct address
if (PagePrivate(page) && !try_to_release_page(page, GFP_KERNEL))
return 0;

- write_lock_irq(&mapping->tree_lock);
+ spin_lock_irq(&mapping->tree_lock);
if (PageDirty(page))
goto failed;

BUG_ON(PagePrivate(page));
__remove_from_page_cache(page);
- write_unlock_irq(&mapping->tree_lock);
+ spin_unlock_irq(&mapping->tree_lock);
ClearPageUptodate(page);
page_cache_release(page); /* pagecache ref */
return 1;
failed:
- write_unlock_irq(&mapping->tree_lock);
+ spin_unlock_irq(&mapping->tree_lock);
return 0;
}

Index: linux-2.6/mm/vmscan.c
===================================================================
--- linux-2.6.orig/mm/vmscan.c
+++ linux-2.6/mm/vmscan.c
@@ -391,7 +391,7 @@ int remove_mapping(struct address_space
BUG_ON(mapping != page_mapping(page));

set_page_nonewrefs(page);
- write_lock_irq(&mapping->tree_lock);
+ spin_lock_irq(&mapping->tree_lock);
/*
* The non racy check for a busy page.
*
@@ -426,13 +426,13 @@ int remove_mapping(struct address_space
if (PageSwapCache(page)) {
swp_entry_t swap = { .val = page_private(page) };
__delete_from_swap_cache(page);
- write_unlock_irq(&mapping->tree_lock);
+ spin_unlock_irq(&mapping->tree_lock);
swap_free(swap);
goto free_it;
}

__remove_from_page_cache(page);
- write_unlock_irq(&mapping->tree_lock);
+ spin_unlock_irq(&mapping->tree_lock);

free_it:
__clear_page_nonewrefs(page);
@@ -440,7 +440,7 @@ free_it:
return 1;

cannot_free:
- write_unlock_irq(&mapping->tree_lock);
+ spin_unlock_irq(&mapping->tree_lock);
clear_page_nonewrefs(page);
return 0;
}
Index: linux-2.6/mm/page-writeback.c
===================================================================
--- linux-2.6.orig/mm/page-writeback.c
+++ linux-2.6/mm/page-writeback.c
@@ -765,7 +765,7 @@ int __set_page_dirty_no_writeback(struct
* mapping is pinned by the vma's ->vm_file reference.
*
* We take care to handle the case where the page was truncated from the
- * mapping by re-checking page_mapping() insode tree_lock.
+ * mapping by re-checking page_mapping() inside tree_lock.
*/
int __set_page_dirty_nobuffers(struct page *page)
{
@@ -776,7 +776,7 @@ int __set_page_dirty_nobuffers(struct pa
if (!mapping)
return 1;

- write_lock_irq(&mapping->tree_lock);
+ spin_lock_irq(&mapping->tree_lock);
mapping2 = page_mapping(page);
if (mapping2) { /* Race with truncate? */
BUG_ON(mapping2 != mapping);
@@ -787,7 +787,7 @@ int __set_page_dirty_nobuffers(struct pa
radix_tree_tag_set(&mapping->page_tree,
page_index(page), PAGECACHE_TAG_DIRTY);
}
- write_unlock_irq(&mapping->tree_lock);
+ spin_unlock_irq(&mapping->tree_lock);
if (mapping->host) {
/* !PageAnon && !swapper_space */
__mark_inode_dirty(mapping->host, I_DIRTY_PAGES);
@@ -919,33 +919,32 @@ EXPORT_SYMBOL(clear_page_dirty_for_io);
int test_clear_page_writeback(struct page *page)
{
struct address_space *mapping = page_mapping(page);
- int ret;

if (mapping) {
unsigned long flags;
+ int ret;

- write_lock_irqsave(&mapping->tree_lock, flags);
+ spin_lock_irqsave(&mapping->tree_lock, flags);
ret = TestClearPageWriteback(page);
if (ret)
radix_tree_tag_clear(&mapping->page_tree,
page_index(page),
PAGECACHE_TAG_WRITEBACK);
- write_unlock_irqrestore(&mapping->tree_lock, flags);
- } else {
- ret = TestClearPageWriteback(page);
+ spin_unlock_irqrestore(&mapping->tree_lock, flags);
+ return ret;
}
- return ret;
+ return TestClearPageWriteback(page);
}

int test_set_page_writeback(struct page *page)
{
struct address_space *mapping = page_mapping(page);
- int ret;

if (mapping) {
unsigned long flags;
+ int ret;

- write_lock_irqsave(&mapping->tree_lock, flags);
+ spin_lock_irqsave(&mapping->tree_lock, flags);
ret = TestSetPageWriteback(page);
if (!ret)
radix_tree_tag_set(&mapping->page_tree,
@@ -955,11 +954,10 @@ int test_set_page_writeback(struct page
radix_tree_tag_clear(&mapping->page_tree,
page_index(page),
PAGECACHE_TAG_DIRTY);
- write_unlock_irqrestore(&mapping->tree_lock, flags);
- } else {
- ret = TestSetPageWriteback(page);
+ spin_unlock_irqrestore(&mapping->tree_lock, flags);
+ return ret;
}
- return ret;
+ return TestSetPageWriteback(page);

}
EXPORT_SYMBOL(test_set_page_writeback);
Index: linux-2.6/include/asm-arm/cacheflush.h
===================================================================
--- linux-2.6.orig/include/asm-arm/cacheflush.h
+++ linux-2.6/include/asm-arm/cacheflush.h
@@ -405,9 +405,9 @@ static inline void flush_anon_page(struc
}

#define flush_dcache_mmap_lock(mapping) \
- write_lock_irq(&(mapping)->tree_lock)
+ spin_lock_irq(&(mapping)->tree_lock)
#define flush_dcache_mmap_unlock(mapping) \
- write_unlock_irq(&(mapping)->tree_lock)
+ spin_unlock_irq(&(mapping)->tree_lock)

#define flush_icache_user_range(vma,page,addr,len) \
flush_dcache_page(page)
Index: linux-2.6/include/asm-parisc/cacheflush.h
===================================================================
--- linux-2.6.orig/include/asm-parisc/cacheflush.h
+++ linux-2.6/include/asm-parisc/cacheflush.h
@@ -45,9 +45,9 @@ void flush_cache_mm(struct mm_struct *mm
extern void flush_dcache_page(struct page *page);

#define flush_dcache_mmap_lock(mapping) \
- write_lock_irq(&(mapping)->tree_lock)
+ spin_lock_irq(&(mapping)->tree_lock)
#define flush_dcache_mmap_unlock(mapping) \
- write_unlock_irq(&(mapping)->tree_lock)
+ spin_unlock_irq(&(mapping)->tree_lock)

#define flush_icache_page(vma,page) do { \
flush_kernel_dcache_page(page); \
Index: linux-2.6/mm/migrate.c
===================================================================
--- linux-2.6.orig/mm/migrate.c
+++ linux-2.6/mm/migrate.c
@@ -304,14 +304,14 @@ static int migrate_page_move_mapping(str
}

set_page_nonewrefs(page);
- write_lock_irq(&mapping->tree_lock);
+ spin_lock_irq(&mapping->tree_lock);

pslot = radix_tree_lookup_slot(&mapping->page_tree,
page_index(page));

if (page_count(page) != 2 + !!PagePrivate(page) ||
(struct page *)radix_tree_deref_slot(pslot) != page) {
- write_unlock_irq(&mapping->tree_lock);
+ spin_unlock_irq(&mapping->tree_lock);
clear_page_nonewrefs(page);
return -EAGAIN;
}
@@ -329,7 +329,7 @@ static int migrate_page_move_mapping(str

radix_tree_replace_slot(pslot, newpage);
page->mapping = NULL;
- write_unlock_irq(&mapping->tree_lock);
+ spin_unlock_irq(&mapping->tree_lock);
clear_page_nonewrefs(page);

/*