Messages in this thread |  | | | From | Dmitry Monakhov <> | | Subject | Re: [PATCH] relay: move remove_buf_file inside relay_close_buf | | Date | Tue, 06 Apr 2010 13:34:33 +0400 |
| |
add Tom Zanussi to recipients. Tom, please take a look at the patch, it is simple and clean and it able to solve long standing blktrace related bug. Dmitry Monakhov <dmonakhov@openvz.org> writes: > 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) > > 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. > > We don't have to wait this long. File may be deleted > inside relay_close_buf(). > > Signed-off-by: Dmitry Monakhov <dmonakhov@openvz.org> > --- > kernel/relay.c | 2 +- > 1 files changed, 1 insertions(+), 1 deletions(-) > > diff --git a/kernel/relay.c b/kernel/relay.c > index c705a41..dcf71c8 100644 > --- a/kernel/relay.c > +++ b/kernel/relay.c > @@ -237,7 +237,6 @@ 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); > } > > @@ -487,6 +486,7 @@ 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); > }
|  |