linux-kernel - [PATCH REBASED 6/6] fs: Use killable down_read() in iterate

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Date:   Fri, 29 Sep 2017 19:06:48 +0300
From:   Kirill Tkhai <ktkhai@...tuozzo.com>
To:     linux-ia64@...r.kernel.org, avagin@...tuozzo.com,
        peterz@...radead.org, heiko.carstens@...ibm.com, hpa@...or.com,
        gorcunov@...tuozzo.com, linux-arch@...r.kernel.org,
        linux-s390@...r.kernel.org, x86@...nel.org, mingo@...hat.com,
        mattst88@...il.com, fenghua.yu@...el.com, arnd@...db.de,
        ktkhai@...tuozzo.com, ink@...assic.park.msu.ru, tglx@...utronix.de,
        rth@...ddle.net, tony.luck@...el.com, linux-kernel@...r.kernel.org,
        linux-alpha@...r.kernel.org, schwidefsky@...ibm.com,
        davem@...emloft.net, rientjes@...gle.com, viro@...iv.linux.org.uk
Subject: [PATCH REBASED 6/6] fs: Use killable down_read() in iterate_dir()

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 <ktkhai@...tuozzo.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)) {