[PATCH REBASED 6/6] fs: Use killable down_read() in iterate_dir()

[Kirill Tkhai]

There was mutex_lock_interruptible() initially, and it was changed
to rwsem, but there were not killable rwsem primitives that time.
>From commit 9902af79c01a:

    "The main issue is the lack of down_write_killable(), so the places
     like readdir.c switched to plain inode_lock(); once killable
     variants of rwsem primitives appear, that'll be dealt with"

Use down_read_killable() same as down_write_killable() in !shared
case, as concurrent inode_lock() may take much time, that may be
wanted to be interrupted by user.

Signed-off-by: Kirill Tkhai <ktk...@virtuozzo.com>
---
 fs/readdir.c |   11 +++++------
 1 file changed, 5 insertions(+), 6 deletions(-)

diff --git a/fs/readdir.c b/fs/readdir.c
index 89659549c09d..7c584bbb4ce3 100644
--- a/fs/readdir.c
+++ b/fs/readdir.c
@@ -36,13 +36,12 @@ int iterate_dir(struct file *file, struct dir_context *ctx)
        if (res)
                goto out;
 
-       if (shared) {
-               inode_lock_shared(inode);
-       } else {
+       if (shared)
+               res = down_read_killable(&inode->i_rwsem);
+       else
                res = down_write_killable(&inode->i_rwsem);
-               if (res)
-                       goto out;
-       }
+       if (res)
+               goto out;
 
        res = -ENOENT;
        if (!IS_DEADDIR(inode)) {