patch-2.3.7 linux/mm/swap_state.c

• Lines: 242
• Date: Sun Jun 20 15:58:20 1999
• Orig file: v2.3.6/linux/mm/swap_state.c
• Orig date: Wed Jan 13 09:54:50 1999

diff -u --recursive --new-file v2.3.6/linux/mm/swap_state.c linux/mm/swap_state.c
@@ -25,7 +25,31 @@
  * ensure that any mistaken dereferences of this structure cause a
  * kernel oops.
  */
-struct inode swapper_inode;
+
+static struct inode_operations swapper_inode_operations = {
+	NULL,				/* default file operations */
+	NULL,				/* create */
+	NULL,				/* lookup */
+	NULL,				/* link */
+	NULL,				/* unlink */
+	NULL,				/* symlink */
+	NULL,				/* mkdir */
+	NULL,				/* rmdir */
+	NULL,				/* mknod */
+	NULL,				/* rename */
+	NULL,				/* readlink */
+	NULL,				/* follow_link */
+	NULL,				/* bmap */
+	NULL,				/* readpage */
+	NULL,				/* writepage */
+	block_flushpage,		/* flushpage */
+	NULL,				/* truncate */
+	NULL,				/* permission */
+	NULL,				/* smap */
+	NULL				/* revalidate */
+};
+
+struct inode swapper_inode = { i_op: &swapper_inode_operations };
 
 #ifdef SWAP_CACHE_INFO
 unsigned long swap_cache_add_total = 0;
@@ -49,20 +73,20 @@
 #endif
 #ifdef DEBUG_SWAP
 	printk("DebugVM: add_to_swap_cache(%08lx count %d, entry %08lx)\n",
-	       page_address(page), atomic_read(&page->count), entry);
+		   page_address(page), page_count(page), entry);
 #endif
 	if (PageTestandSetSwapCache(page)) {
 		printk(KERN_ERR "swap_cache: replacing non-empty entry %08lx "
-		       "on page %08lx\n",
-		       page->offset, page_address(page));
+			   "on page %08lx\n",
+			   page->offset, page_address(page));
 		return 0;
 	}
 	if (page->inode) {
 		printk(KERN_ERR "swap_cache: replacing page-cached entry "
-		       "on page %08lx\n", page_address(page));
+			   "on page %08lx\n", page_address(page));
 		return 0;
 	}
-	atomic_inc(&page->count);
+	get_page(page);
 	page->inode = &swapper_inode;
 	page->offset = entry;
 	add_page_to_hash_queue(page, &swapper_inode, entry);
@@ -111,7 +135,7 @@
 	result = 1;
 #ifdef DEBUG_SWAP
 	printk("DebugVM: swap_duplicate(entry %08lx, count now %d)\n",
-	       entry, p->swap_map[offset]);
+		   entry, p->swap_map[offset]);
 #endif
 out:
 	return result;
@@ -127,7 +151,7 @@
 bad_unused:
 	printk(KERN_ERR
 		"swap_duplicate at %8p: entry %08lx, unused page\n", 
-	       __builtin_return_address(0), entry);
+		   __builtin_return_address(0), entry);
 	goto out;
 }
 
@@ -153,7 +177,7 @@
 	retval = p->swap_map[offset];
 #ifdef DEBUG_SWAP
 	printk("DebugVM: swap_count(entry %08lx, count %d)\n",
-	       entry, retval);
+		   entry, retval);
 #endif
 out:
 	return retval;
@@ -163,16 +187,16 @@
 	goto out;
 bad_file:
 	printk(KERN_ERR
-	       "swap_count: entry %08lx, nonexistent swap file!\n", entry);
+		   "swap_count: entry %08lx, nonexistent swap file!\n", entry);
 	goto out;
 bad_offset:
 	printk(KERN_ERR
-	       "swap_count: entry %08lx, offset exceeds max!\n", entry);
+		   "swap_count: entry %08lx, offset exceeds max!\n", entry);
 	goto out;
 bad_unused:
 	printk(KERN_ERR
-	       "swap_count at %8p: entry %08lx, unused page!\n", 
-	       __builtin_return_address(0), entry);
+		   "swap_count at %8p: entry %08lx, unused page!\n", 
+		   __builtin_return_address(0), entry);
 	goto out;
 }
 
@@ -190,18 +214,17 @@
 
 #ifdef DEBUG_SWAP
 	printk("DebugVM: remove_from_swap_cache(%08lx count %d)\n",
-	       page_address(page), atomic_read(&page->count));
+		   page_address(page), page_count(page));
 #endif
-	PageClearSwapCache (page);
+	PageClearSwapCache(page);
 	remove_inode_page(page);
 }
 
-
 /*
  * This must be called only on pages that have
  * been verified to be in the swap cache.
  */
-void delete_from_swap_cache(struct page *page)
+void __delete_from_swap_cache(struct page *page)
 {
 	long entry = page->offset;
 
@@ -210,13 +233,27 @@
 #endif
 #ifdef DEBUG_SWAP
 	printk("DebugVM: delete_from_swap_cache(%08lx count %d, "
-	       "entry %08lx)\n",
-	       page_address(page), atomic_read(&page->count), entry);
+		   "entry %08lx)\n",
+		   page_address(page), page_count(page), entry);
 #endif
 	remove_from_swap_cache (page);
 	swap_free (entry);
 }
 
+/*
+ * This must be called only on pages that have
+ * been verified to be in the swap cache.
+ */
+void delete_from_swap_cache(struct page *page)
+{
+	lock_page(page);
+
+	__delete_from_swap_cache(page);
+
+	UnlockPage(page);
+	page_cache_release(page);
+}
+
 /* 
  * Perform a free_page(), also freeing any swap cache associated with
  * this page if it is the last user of the page. 
@@ -229,18 +266,18 @@
 	/* 
 	 * If we are the only user, then free up the swap cache. 
 	 */
-	if (PageSwapCache(page) && !is_page_shared(page)) {
+	if (PageSwapCache(page) && !is_page_shared(page))
 		delete_from_swap_cache(page);
-	}
 	
 	__free_page(page);
 }
 
 
 /*
- * Lookup a swap entry in the swap cache.  We need to be careful about
- * locked pages.  A found page will be returned with its refcount
- * incremented.
+ * Lookup a swap entry in the swap cache. A found page will be returned
+ * unlocked and with its refcount incremented - we rely on the kernel
+ * lock getting page table operations atomic even if we drop the page
+ * lock before returning.
  */
 
 struct page * lookup_swap_cache(unsigned long entry)
@@ -251,23 +288,21 @@
 	swap_cache_find_total++;
 #endif
 	while (1) {
-		found = find_page(&swapper_inode, entry);
+		found = find_lock_page(&swapper_inode, entry);
 		if (!found)
 			return 0;
 		if (found->inode != &swapper_inode || !PageSwapCache(found))
 			goto out_bad;
-		if (!PageLocked(found)) {
 #ifdef SWAP_CACHE_INFO
-			swap_cache_find_success++;
+		swap_cache_find_success++;
 #endif
-			return found;
-		}
-		__free_page(found);
-		__wait_on_page(found);
+		UnlockPage(found);
+		return found;
 	}
 
 out_bad:
 	printk (KERN_ERR "VM: Found a non-swapper swap page!\n");
+	UnlockPage(found);
 	__free_page(found);
 	return 0;
 }
@@ -288,7 +323,7 @@
 	
 #ifdef DEBUG_SWAP
 	printk("DebugVM: read_swap_cache_async entry %08lx%s\n",
-	       entry, wait ? ", wait" : "");
+		   entry, wait ? ", wait" : "");
 #endif
 	/*
 	 * Make sure the swap entry is still in use.
@@ -319,12 +354,12 @@
 	if (!add_to_swap_cache(new_page, entry))
 		goto out_free_page;
 
-	set_bit(PG_locked, &new_page->flags);
+	LockPage(new_page);
 	rw_swap_page(READ, entry, (char *) new_page_addr, wait);
 #ifdef DEBUG_SWAP
 	printk("DebugVM: read_swap_cache_async created "
-	       "entry %08lx at %p\n",
-	       entry, (char *) page_address(new_page));
+		   "entry %08lx at %p\n",
+			entry, (char *) page_address(new_page));
 #endif
 	return new_page;
 
@@ -335,3 +370,4 @@
 out:
 	return found_page;
 }
+