patch-2.3.99-pre6 linux/mm/filemap.c

• Lines: 263
• Date: Wed Apr 26 15:06:25 2000
• Orig file: v2.3.99-pre5/linux/mm/filemap.c
• Orig date: Tue Apr 11 15:09:25 2000

diff -u --recursive --new-file v2.3.99-pre5/linux/mm/filemap.c linux/mm/filemap.c
@@ -44,6 +44,7 @@
 atomic_t page_cache_size = ATOMIC_INIT(0);
 unsigned int page_hash_bits;
 struct page **page_hash_table;
+struct list_head lru_cache;
 
 spinlock_t pagecache_lock = SPIN_LOCK_UNLOCKED;
 /*
@@ -77,6 +78,15 @@
 	atomic_dec(&page_cache_size);
 }
 
+static inline int sync_page(struct page *page)
+{
+	struct address_space *mapping = page->mapping;
+
+	if (mapping && mapping->a_ops && mapping->a_ops->sync_page)
+		return mapping->a_ops->sync_page(page);
+	return 0;
+}
+
 /*
  * 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
@@ -87,6 +97,9 @@
 	if (!PageLocked(page))
 		PAGE_BUG(page);
 
+	/* Initiate completion of any async operations */
+	sync_page(page);
+
 	spin_lock(&pagecache_lock);
 	remove_page_from_inode_queue(page);
 	remove_page_from_hash_queue(page);
@@ -99,6 +112,7 @@
 	struct list_head *head, *curr;
 	struct page * page;
 
+ repeat:
 	head = &inode->i_mapping->pages;
 	spin_lock(&pagecache_lock);
 	curr = head->next;
@@ -110,14 +124,13 @@
 		/* We cannot invalidate a locked page */
 		if (TryLockPage(page))
 			continue;
+		spin_unlock(&pagecache_lock);
 
 		lru_cache_del(page);
-		remove_page_from_inode_queue(page);
-		remove_page_from_hash_queue(page);
-		page->mapping = NULL;
+		remove_inode_page(page);
 		UnlockPage(page);
-
 		page_cache_release(page);
+		goto repeat;
 	}
 	spin_unlock(&pagecache_lock);
 }
@@ -149,11 +162,16 @@
 
 		/* page wholly truncated - free it */
 		if (offset >= start) {
+			if (TryLockPage(page)) {
+				spin_unlock(&pagecache_lock);
+				get_page(page);
+				wait_on_page(page);
+				put_page(page);
+				goto repeat;
+			}
 			get_page(page);
 			spin_unlock(&pagecache_lock);
 
-			lock_page(page);
-
 			if (!page->buffers || block_flushpage(page, 0))
 				lru_cache_del(page);
 
@@ -191,11 +209,13 @@
 			continue;
 
 		/* partial truncate, clear end of page */
+		if (TryLockPage(page)) {
+			spin_unlock(&pagecache_lock);
+			goto repeat;
+		}
 		get_page(page);
 		spin_unlock(&pagecache_lock);
 
-		lock_page(page);
-
 		memclear_highpage_flush(page, partial, PAGE_CACHE_SIZE-partial);
 		if (page->buffers)
 			block_flushpage(page, partial);
@@ -208,6 +228,9 @@
 		 */
 		UnlockPage(page);
 		page_cache_release(page);
+		get_page(page);
+		wait_on_page(page);
+		put_page(page);
 		goto repeat;
 	}
 	spin_unlock(&pagecache_lock);
@@ -215,46 +238,55 @@
 
 int shrink_mmap(int priority, int gfp_mask, zone_t *zone)
 {
-	int ret = 0, count;
+	int ret = 0, loop = 0, count;
 	LIST_HEAD(young);
 	LIST_HEAD(old);
 	LIST_HEAD(forget);
 	struct list_head * page_lru, * dispose;
-	struct page * page;
-
+	struct page * page = NULL;
+	struct zone_struct * p_zone;
+	int maxloop = 256 >> priority;
+	
 	if (!zone)
 		BUG();
 
-	count = nr_lru_pages / (priority+1);
+	count = nr_lru_pages >> priority;
+	if (!count)
+		return ret;
 
 	spin_lock(&pagemap_lru_lock);
-
-	while (count > 0 && (page_lru = zone->lru_cache.prev) != &zone->lru_cache) {
+again:
+	/* we need pagemap_lru_lock for list_del() ... subtle code below */
+	while (count > 0 && (page_lru = lru_cache.prev) != &lru_cache) {
 		page = list_entry(page_lru, struct page, lru);
 		list_del(page_lru);
+		p_zone = page->zone;
 
-		dispose = &zone->lru_cache;
-		if (test_and_clear_bit(PG_referenced, &page->flags))
-			/* Roll the page at the top of the lru list,
-			 * we could also be more aggressive putting
-			 * the page in the young-dispose-list, so
-			 * avoiding to free young pages in each pass.
-			 */
-			goto dispose_continue;
-
+		/*
+		 * These two tests are there to make sure we don't free too
+		 * many pages from the "wrong" zone. We free some anyway,
+		 * they are the least recently used pages in the system.
+		 * When we don't free them, leave them in &old.
+		 */
 		dispose = &old;
-		/* don't account passes over not DMA pages */
-		if (zone && (!memclass(page->zone, zone)))
+		if (p_zone != zone && (loop > (maxloop / 4) ||
+				p_zone->free_pages > p_zone->pages_high))
 			goto dispose_continue;
 
-		count--;
-
+		/* The page is in use, or was used very recently, put it in
+		 * &young to make sure that we won't try to free it the next
+		 * time */
 		dispose = &young;
 
-		/* avoid unscalable SMP locking */
+		if (test_and_clear_bit(PG_referenced, &page->flags))
+			goto dispose_continue;
+
+		count--;
 		if (!page->buffers && page_count(page) > 1)
 			goto dispose_continue;
 
+		/* Page not used -> free it; if that fails -> &old */
+		dispose = &old;
 		if (TryLockPage(page))
 			goto dispose_continue;
 
@@ -327,6 +359,7 @@
 		list_add(page_lru, dispose);
 		continue;
 
+		/* we're holding pagemap_lru_lock, so we can just loop again */
 dispose_continue:
 		list_add(page_lru, dispose);
 	}
@@ -342,9 +375,14 @@
 	/* nr_lru_pages needs the spinlock */
 	nr_lru_pages--;
 
+	loop++;
+	/* wrong zone?  not looped too often?    roll again... */
+	if (page->zone != zone && loop < maxloop)
+		goto again;
+
 out:
-	list_splice(&young, &zone->lru_cache);
-	list_splice(&old, zone->lru_cache.prev);
+	list_splice(&young, &lru_cache);
+	list_splice(&old, lru_cache.prev);
 
 	spin_unlock(&pagemap_lru_lock);
 
@@ -467,6 +505,9 @@
 	struct page *alias;
 	unsigned long flags;
 
+	if (PageLocked(page))
+		BUG();
+
 	flags = page->flags & ~((1 << PG_uptodate) | (1 << PG_error) | (1 << PG_dirty));
 	page->flags = flags | (1 << PG_locked) | (1 << PG_referenced);
 	get_page(page);
@@ -574,7 +615,7 @@
 
 	add_wait_queue(&page->wait, &wait);
 	do {
-		run_task_queue(&tq_disk);
+		sync_page(page);
 		set_task_state(tsk, TASK_UNINTERRUPTIBLE);
 		if (!PageLocked(page))
 			break;
@@ -619,7 +660,7 @@
 		struct task_struct *tsk = current;
 		DECLARE_WAITQUEUE(wait, tsk);
 
-		run_task_queue(&tq_disk);
+		sync_page(page);
 
 		__set_task_state(tsk, TASK_UNINTERRUPTIBLE);
 		add_wait_queue(&page->wait, &wait);
@@ -669,7 +710,7 @@
 		struct task_struct *tsk = current;
 		DECLARE_WAITQUEUE(wait, tsk);
 
-		run_task_queue(&tq_disk);
+		sync_page(page);
 
 		__set_task_state(tsk, TASK_UNINTERRUPTIBLE);
 		add_wait_queue(&page->wait, &wait);
@@ -1496,7 +1537,7 @@
 	 * mmap_sem is held.
 	 */
 	lock_page(page);
-	result = inode->i_mapping->a_ops->writepage(dentry, page);
+	result = inode->i_mapping->a_ops->writepage(file, dentry, page);
 	UnlockPage(page);
 	return result;
 }
@@ -1707,8 +1748,8 @@
 		error = vma->vm_ops->sync(vma, start, end-start, flags);
 		if (!error && (flags & MS_SYNC)) {
 			struct file * file = vma->vm_file;
-			if (file)
-				error = file_fsync(file, file->f_dentry);
+			if (file && file->f_op && file->f_op->fsync)
+				error = file->f_op->fsync(file, file->f_dentry);
 		}
 		return error;
 	}