From b8d4a5bf6a049303a29a3275f463f09a490b50ea Mon Sep 17 00:00:00 2001
From: Dmitry Monakhov <dmonakhov@openvz.org>
Date: Mon, 22 Apr 2013 11:41:41 +0400
Subject: [PATCH] relay: move remove_buf_file inside relay_close_buf
Currently remove_buf_file callback is called from from kobject
release method. This result in follow issue:
# blktrace -d /dev/sda1 -d /dev/sda -o test
blktrace_setup()
dir = create_dir()
rchan = relay_open(dir,...)
->create_buf_file_callback
buf_file = debugfs_create_file(dir, )
Userspace will open buf_file.
Later we make a decision to stop tracing
blktrace_down()
relay_close(rhcan) /* just decrement kobj reference */
/* since it is not zero then callback not called */
debugfs_remove(dir) /* FAIL due to non empty dir */
Later user space will close the file and file will be deleted,
but directory still exist.
user_space_close()
->file_release
->release_buf_file_callback
->debugfs_remove(buf_file
## TESTCASE:
# blktrace -d /dev/sda1 -d /dev/sda -o test
# After that blktrace infrastructure will remain broken in
# an unusable state so: blktrace -d /dev/sda1 will not work.
In fact this is general issue, blktrace is just one of examples.
We can not reliably remove parent dir until all users close the
buf_file.
Solution: We don't have to wait that long. File should be deleted inside
relay_close_buf().
Signed-off-by: Dmitry Monakhov <dmonakhov@openvz.org>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
---
kernel/relay.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/kernel/relay.c b/kernel/relay.c
index 01ab081ac53a..a0d200012adb 100644
--- a/kernel/relay.c
+++ b/kernel/relay.c
@@ -234,7 +234,6 @@ static void relay_destroy_buf(struct rchan_buf *buf)
static void relay_remove_buf(struct kref *kref)
{
struct rchan_buf *buf = container_of(kref, struct rchan_buf, kref);
- buf->chan->cb->remove_buf_file(buf->dentry);
relay_destroy_buf(buf);
}
@@ -484,6 +483,7 @@ static void relay_close_buf(struct rchan_buf *buf)
{
buf->finalized = 1;
del_timer_sync(&buf->timer);
+ buf->chan->cb->remove_buf_file(buf->dentry);
kref_put(&buf->kref, relay_remove_buf);
}
--
2.20.1