Merge commit 'v2.6.39' into for-2.6.40/core

Since for-2.6.40/core was forked off the 2.6.39 devel tree, we've
had churn in the core area that makes it difficult to handle
patches for eg cfq or blk-throttle. Instead of requiring that they
be based in older versions with bugs that have been fixed later
in the rc cycle, merge in 2.6.39 final.

Also fixes up conflicts in the below files.

Conflicts:
	drivers/block/paride/pcd.c
	drivers/cdrom/viocd.c
	drivers/ide/ide-cd.c

Signed-off-by: Jens Axboe <jaxboe@fusionio.com>

1 files changed, 83 insertions, 66 deletions

diff --git a/mm/shmem.c b/mm/shmem.c
index 8fa27e4e582a..dfc7069102ee 100644
--- a/mm/shmem.c
+++ b/mm/shmem.c
@@ -852,7 +852,7 @@ static inline int shmem_find_swp(swp_entry_t entry, swp_entry_t *dir, swp_entry_
 
 static int shmem_unuse_inode(struct shmem_inode_info *info, swp_entry_t entry, struct page *page)
 {
-	struct inode *inode;
+	struct address_space *mapping;
 	unsigned long idx;
 	unsigned long size;
 	unsigned long limit;
@@ -875,8 +875,10 @@ static int shmem_unuse_inode(struct shmem_inode_info *info, swp_entry_t entry, s
 	if (size > SHMEM_NR_DIRECT)
 		size = SHMEM_NR_DIRECT;
 	offset = shmem_find_swp(entry, ptr, ptr+size);
-	if (offset >= 0)
+	if (offset >= 0) {
+		shmem_swp_balance_unmap();
 		goto found;
+	}
 	if (!info->i_indirect)
 		goto lost2;
 
@@ -914,11 +916,11 @@ static int shmem_unuse_inode(struct shmem_inode_info *info, swp_entry_t entry, s
 			if (size > ENTRIES_PER_PAGE)
 				size = ENTRIES_PER_PAGE;
 			offset = shmem_find_swp(entry, ptr, ptr+size);
-			shmem_swp_unmap(ptr);
 			if (offset >= 0) {
 				shmem_dir_unmap(dir);
 				goto found;
 			}
+			shmem_swp_unmap(ptr);
 		}
 	}
 lost1:
@@ -928,8 +930,7 @@ lost2:
 	return 0;
 found:
 	idx += offset;
-	inode = igrab(&info->vfs_inode);
-	spin_unlock(&info->lock);
+	ptr += offset;
 
 	/*
 	 * Move _head_ to start search for next from here.
@@ -940,37 +941,18 @@ found:
 	 */
 	if (shmem_swaplist.next != &info->swaplist)
 		list_move_tail(&shmem_swaplist, &info->swaplist);
-	mutex_unlock(&shmem_swaplist_mutex);
 
-	error = 1;
-	if (!inode)
-		goto out;
 	/*
-	 * Charge page using GFP_KERNEL while we can wait.
-	 * Charged back to the user(not to caller) when swap account is used.
-	 * add_to_page_cache() will be called with GFP_NOWAIT.
+	 * We rely on shmem_swaplist_mutex, not only to protect the swaplist,
+	 * but also to hold up shmem_evict_inode(): so inode cannot be freed
+	 * beneath us (pagelock doesn't help until the page is in pagecache).
 	 */
-	error = mem_cgroup_cache_charge(page, current->mm, GFP_KERNEL);
-	if (error)
-		goto out;
-	error = radix_tree_preload(GFP_KERNEL);
-	if (error) {
-		mem_cgroup_uncharge_cache_page(page);
-		goto out;
-	}
-	error = 1;
-
-	spin_lock(&info->lock);
-	ptr = shmem_swp_entry(info, idx, NULL);
-	if (ptr && ptr->val == entry.val) {
-		error = add_to_page_cache_locked(page, inode->i_mapping,
-						idx, GFP_NOWAIT);
-		/* does mem_cgroup_uncharge_cache_page on error */
-	} else	/* we must compensate for our precharge above */
-		mem_cgroup_uncharge_cache_page(page);
+	mapping = info->vfs_inode.i_mapping;
+	error = add_to_page_cache_locked(page, mapping, idx, GFP_NOWAIT);
+	/* which does mem_cgroup_uncharge_cache_page on error */
 
 	if (error == -EEXIST) {
-		struct page *filepage = find_get_page(inode->i_mapping, idx);
+		struct page *filepage = find_get_page(mapping, idx);
 		error = 1;
 		if (filepage) {
 			/*
@@ -990,14 +972,8 @@ found:
 		swap_free(entry);
 		error = 1;	/* not an error, but entry was found */
 	}
-	if (ptr)
-		shmem_swp_unmap(ptr);
+	shmem_swp_unmap(ptr);
 	spin_unlock(&info->lock);
-	radix_tree_preload_end();
-out:
-	unlock_page(page);
-	page_cache_release(page);
-	iput(inode);		/* allows for NULL */
 	return error;
 }
 
@@ -1009,6 +985,26 @@ int shmem_unuse(swp_entry_t entry, struct page *page)
 	struct list_head *p, *next;
 	struct shmem_inode_info *info;
 	int found = 0;
+	int error;
+
+	/*
+	 * Charge page using GFP_KERNEL while we can wait, before taking
+	 * the shmem_swaplist_mutex which might hold up shmem_writepage().
+	 * Charged back to the user (not to caller) when swap account is used.
+	 * add_to_page_cache() will be called with GFP_NOWAIT.
+	 */
+	error = mem_cgroup_cache_charge(page, current->mm, GFP_KERNEL);
+	if (error)
+		goto out;
+	/*
+	 * Try to preload while we can wait, to not make a habit of
+	 * draining atomic reserves; but don't latch on to this cpu,
+	 * it's okay if sometimes we get rescheduled after this.
+	 */
+	error = radix_tree_preload(GFP_KERNEL);
+	if (error)
+		goto uncharge;
+	radix_tree_preload_end();
 
 	mutex_lock(&shmem_swaplist_mutex);
 	list_for_each_safe(p, next, &shmem_swaplist) {
@@ -1016,17 +1012,19 @@ int shmem_unuse(swp_entry_t entry, struct page *page)
 		found = shmem_unuse_inode(info, entry, page);
 		cond_resched();
 		if (found)
-			goto out;
+			break;
 	}
 	mutex_unlock(&shmem_swaplist_mutex);
-	/*
-	 * Can some race bring us here?  We've been holding page lock,
-	 * so I think not; but would rather try again later than BUG()
-	 */
+
+uncharge:
+	if (!found)
+		mem_cgroup_uncharge_cache_page(page);
+	if (found < 0)
+		error = found;
+out:
 	unlock_page(page);
 	page_cache_release(page);
-out:
-	return (found < 0) ? found : 0;
+	return error;
 }
 
 /*
@@ -1064,7 +1062,25 @@ static int shmem_writepage(struct page *page, struct writeback_control *wbc)
 	else
 		swap.val = 0;
 
+	/*
+	 * Add inode to shmem_unuse()'s list of swapped-out inodes,
+	 * if it's not already there.  Do it now because we cannot take
+	 * mutex while holding spinlock, and must do so before the page
+	 * is moved to swap cache, when its pagelock no longer protects
+	 * the inode from eviction.  But don't unlock the mutex until
+	 * we've taken the spinlock, because shmem_unuse_inode() will
+	 * prune a !swapped inode from the swaplist under both locks.
+	 */
+	if (swap.val) {
+		mutex_lock(&shmem_swaplist_mutex);
+		if (list_empty(&info->swaplist))
+			list_add_tail(&info->swaplist, &shmem_swaplist);
+	}
+
 	spin_lock(&info->lock);
+	if (swap.val)
+		mutex_unlock(&shmem_swaplist_mutex);
+
 	if (index >= info->next_index) {
 		BUG_ON(!(info->flags & SHMEM_TRUNCATE));
 		goto unlock;
@@ -1084,21 +1100,10 @@ static int shmem_writepage(struct page *page, struct writeback_control *wbc)
 		delete_from_page_cache(page);
 		shmem_swp_set(info, entry, swap.val);
 		shmem_swp_unmap(entry);
-		if (list_empty(&info->swaplist))
-			inode = igrab(inode);
-		else
-			inode = NULL;
 		spin_unlock(&info->lock);
 		swap_shmem_alloc(swap);
 		BUG_ON(page_mapped(page));
 		swap_writepage(page, wbc);
-		if (inode) {
-			mutex_lock(&shmem_swaplist_mutex);
-			/* move instead of add in case we're racing */
-			list_move_tail(&info->swaplist, &shmem_swaplist);
-			mutex_unlock(&shmem_swaplist_mutex);
-			iput(inode);
-		}
 		return 0;
 	}
 
@@ -1400,20 +1405,14 @@ repeat:
 		if (sbinfo->max_blocks) {
 			if (percpu_counter_compare(&sbinfo->used_blocks,
 						sbinfo->max_blocks) >= 0 ||
-			    shmem_acct_block(info->flags)) {
-				spin_unlock(&info->lock);
-				error = -ENOSPC;
-				goto failed;
-			}
+			    shmem_acct_block(info->flags))
+				goto nospace;
 			percpu_counter_inc(&sbinfo->used_blocks);
 			spin_lock(&inode->i_lock);
 			inode->i_blocks += BLOCKS_PER_PAGE;
 			spin_unlock(&inode->i_lock);
-		} else if (shmem_acct_block(info->flags)) {
-			spin_unlock(&info->lock);
-			error = -ENOSPC;
-			goto failed;
-		}
+		} else if (shmem_acct_block(info->flags))
+			goto nospace;
 
 		if (!filepage) {
 			int ret;
@@ -1493,6 +1492,24 @@ done:
 	error = 0;
 	goto out;
 
+nospace:
+	/*
+	 * Perhaps the page was brought in from swap between find_lock_page
+	 * and taking info->lock?  We allow for that at add_to_page_cache_lru,
+	 * but must also avoid reporting a spurious ENOSPC while working on a
+	 * full tmpfs.  (When filepage has been passed in to shmem_getpage, it
+	 * is already in page cache, which prevents this race from occurring.)
+	 */
+	if (!filepage) {
+		struct page *page = find_get_page(mapping, idx);
+		if (page) {
+			spin_unlock(&info->lock);
+			page_cache_release(page);
+			goto repeat;
+		}
+	}
+	spin_unlock(&info->lock);
+	error = -ENOSPC;
 failed:
 	if (*pagep != filepage) {
 		unlock_page(filepage);