From: Vivek Goyal <vgoyal@redhat.com>
To: linux-fsdevel@vger.kernel.org,
virtualization@lists.linux-foundation.org, miklos@szeredi.hu
Cc: linux-kernel@vger.kernel.org, virtio-fs@redhat.com,
vgoyal@redhat.com, stefanha@redhat.com, dgilbert@redhat.com,
mst@redhat.com
Subject: [PATCH 16/18] virtiofs: Use virtio_fs_mutex for races w.r.t ->remove and mount path
Date: Thu, 5 Sep 2019 15:48:57 -0400 [thread overview]
Message-ID: <20190905194859.16219-17-vgoyal@redhat.com> (raw)
In-Reply-To: <20190905194859.16219-1-vgoyal@redhat.com>
It is possible that a mount is in progress and device is being removed at
the same time. Use virtio_fs_mutex to avoid races.
This also takes care of bunch of races and removes some TODO items.
Signed-off-by: Vivek Goyal <vgoyal@redhat.com>
---
fs/fuse/virtio_fs.c | 32 ++++++++++++++++++++++----------
1 file changed, 22 insertions(+), 10 deletions(-)
diff --git a/fs/fuse/virtio_fs.c b/fs/fuse/virtio_fs.c
index 29ec2f5bbbe2..c483482185b6 100644
--- a/fs/fuse/virtio_fs.c
+++ b/fs/fuse/virtio_fs.c
@@ -13,7 +13,9 @@
#include <linux/highmem.h>
#include "fuse_i.h"
-/* List of virtio-fs device instances and a lock for the list */
+/* List of virtio-fs device instances and a lock for the list. Also provides
+ * mutual exclusion in device removal and mounting path
+ */
static DEFINE_MUTEX(virtio_fs_mutex);
static LIST_HEAD(virtio_fs_instances);
@@ -72,17 +74,19 @@ static void release_virtiofs_obj(struct kref *ref)
kfree(vfs);
}
+/* Make sure virtiofs_mutex is held */
static void virtiofs_put(struct virtio_fs *fs)
{
- mutex_lock(&virtio_fs_mutex);
kref_put(&fs->refcount, release_virtiofs_obj);
- mutex_unlock(&virtio_fs_mutex);
}
static void virtio_fs_put(struct fuse_iqueue *fiq)
{
struct virtio_fs *vfs = fiq->priv;
+
+ mutex_lock(&virtio_fs_mutex);
virtiofs_put(vfs);
+ mutex_unlock(&virtio_fs_mutex);
}
static void virtio_fs_drain_queue(struct virtio_fs_vq *fsvq)
@@ -596,9 +600,8 @@ static void virtio_fs_remove(struct virtio_device *vdev)
struct virtio_fs *fs = vdev->priv;
mutex_lock(&virtio_fs_mutex);
+ /* This device is going away. No one should get new reference */
list_del_init(&fs->list);
- mutex_unlock(&virtio_fs_mutex);
-
virtio_fs_stop_all_queues(fs);
virtio_fs_drain_all_queues(fs);
vdev->config->reset(vdev);
@@ -607,6 +610,7 @@ static void virtio_fs_remove(struct virtio_device *vdev)
vdev->priv = NULL;
/* Put device reference on virtio_fs object */
virtiofs_put(fs);
+ mutex_unlock(&virtio_fs_mutex);
}
#ifdef CONFIG_PM_SLEEP
@@ -978,10 +982,15 @@ static int virtio_fs_fill_super(struct super_block *sb)
.no_force_umount = true,
};
- /* TODO lock */
- if (fs->vqs[VQ_REQUEST].fud) {
- pr_err("virtio-fs: device already in use\n");
- err = -EBUSY;
+ mutex_lock(&virtio_fs_mutex);
+
+ /* After holding mutex, make sure virtiofs device is still there.
+ * Though we are holding a refernce to it, drive ->remove might
+ * still have cleaned up virtual queues. In that case bail out.
+ */
+ err = -EINVAL;
+ if (list_empty(&fs->list)) {
+ pr_info("virtio-fs: tag <%s> not found\n", fs->tag);
goto err;
}
@@ -1007,7 +1016,6 @@ static int virtio_fs_fill_super(struct super_block *sb)
fc = fs->vqs[VQ_REQUEST].fud->fc;
- /* TODO take fuse_mutex around this loop? */
for (i = 0; i < fs->nvqs; i++) {
struct virtio_fs_vq *fsvq = &fs->vqs[i];
@@ -1020,6 +1028,7 @@ static int virtio_fs_fill_super(struct super_block *sb)
/* Previous unmount will stop all queues. Start these again */
virtio_fs_start_all_queues(fs);
fuse_send_init(fc, init_req);
+ mutex_unlock(&virtio_fs_mutex);
return 0;
err_free_init_req:
@@ -1027,6 +1036,7 @@ static int virtio_fs_fill_super(struct super_block *sb)
err_free_fuse_devs:
virtio_fs_free_devs(fs);
err:
+ mutex_unlock(&virtio_fs_mutex);
return err;
}
@@ -1100,7 +1110,9 @@ static int virtio_fs_get_tree(struct fs_context *fsc)
fc = kzalloc(sizeof(struct fuse_conn), GFP_KERNEL);
if (!fc) {
+ mutex_lock(&virtio_fs_mutex);
virtiofs_put(fs);
+ mutex_unlock(&virtio_fs_mutex);
return -ENOMEM;
}
--
2.20.1
next prev parent reply other threads:[~2019-09-05 19:50 UTC|newest]
Thread overview: 62+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-09-05 19:48 [PATCH 00/18] virtiofs: Fix various races and cleanups round 1 Vivek Goyal
2019-09-05 19:48 ` [PATCH 01/18] virtiofs: Remove request from processing list before calling end Vivek Goyal
2019-09-06 10:40 ` Stefan Hajnoczi
2019-09-05 19:48 ` [PATCH 02/18] virtiofs: Check whether hiprio queue is connected at submission time Vivek Goyal
2019-09-06 10:43 ` Stefan Hajnoczi
2019-09-05 19:48 ` [PATCH 03/18] virtiofs: Pass fsvq instead of vq as parameter to virtio_fs_enqueue_req Vivek Goyal
2019-09-06 10:44 ` Stefan Hajnoczi
2019-09-05 19:48 ` [PATCH 04/18] virtiofs: Check connected state for VQ_REQUEST queue as well Vivek Goyal
2019-09-06 10:45 ` Stefan Hajnoczi
2019-09-05 19:48 ` [PATCH 05/18] Maintain count of in flight requests for VQ_REQUEST queue Vivek Goyal
2019-09-06 10:46 ` Stefan Hajnoczi
2019-09-05 19:48 ` [PATCH 06/18] virtiofs: ->remove should not clean virtiofs fuse devices Vivek Goyal
2019-09-06 10:47 ` Stefan Hajnoczi
2019-09-05 19:48 ` [PATCH 07/18] virtiofs: Stop virtiofs queues when device is being removed Vivek Goyal
2019-09-06 10:47 ` Stefan Hajnoczi
2019-09-05 19:48 ` [PATCH 08/18] virtiofs: Drain all pending requests during ->remove time Vivek Goyal
2019-09-06 10:52 ` Stefan Hajnoczi
2019-09-06 14:17 ` Vivek Goyal
2019-09-06 14:18 ` Michael S. Tsirkin
2019-09-09 16:10 ` Stefan Hajnoczi
2019-09-08 10:11 ` [Virtio-fs] " piaojun
2019-09-05 19:48 ` [PATCH 09/18] virtiofs: Add an helper to start all the queues Vivek Goyal
2019-09-06 10:54 ` Stefan Hajnoczi
2019-09-05 19:48 ` [PATCH 10/18] virtiofs: Do not use device managed mem for virtio_fs and virtio_fs_vq Vivek Goyal
2019-09-06 10:56 ` Stefan Hajnoczi
2019-09-05 19:48 ` [PATCH 11/18] virtiofs: stop and drain queues after sending DESTROY Vivek Goyal
2019-09-06 11:50 ` Stefan Hajnoczi
2019-09-05 19:48 ` [PATCH 12/18] virtiofs: Use virtio_fs_free_devs() in error path Vivek Goyal
2019-09-06 11:51 ` Stefan Hajnoczi
2019-09-05 19:48 ` [PATCH 13/18] virtiofs: Do not access virtqueue in request submission path Vivek Goyal
2019-09-06 11:52 ` Stefan Hajnoczi
2019-09-05 19:48 ` [PATCH 14/18] virtiofs: Add a fuse_iqueue operation to put() reference Vivek Goyal
2019-09-06 12:00 ` Stefan Hajnoczi
2019-09-06 13:35 ` Vivek Goyal
2019-09-05 19:48 ` [PATCH 15/18] virtiofs: Make virtio_fs object refcounted Vivek Goyal
2019-09-06 12:03 ` Stefan Hajnoczi
2019-09-06 13:50 ` Vivek Goyal
2019-09-09 16:12 ` Stefan Hajnoczi
2019-09-08 11:10 ` [Virtio-fs] " piaojun
2019-09-09 15:35 ` Vivek Goyal
2019-09-05 19:48 ` Vivek Goyal [this message]
2019-09-06 12:05 ` [PATCH 16/18] virtiofs: Use virtio_fs_mutex for races w.r.t ->remove and mount path Stefan Hajnoczi
2019-09-06 13:51 ` Vivek Goyal
2019-09-09 16:13 ` Stefan Hajnoczi
2019-09-08 11:19 ` [Virtio-fs] " piaojun
2019-09-05 19:48 ` [PATCH 17/18] virtiofs: Remove TODO to quiesce/end_requests Vivek Goyal
2019-09-06 12:06 ` Stefan Hajnoczi
2019-09-05 19:48 ` [PATCH 18/18] virtiofs: Remove TODO item from virtio_fs_free_devs() Vivek Goyal
2019-09-06 12:06 ` Stefan Hajnoczi
2019-09-06 8:15 ` [PATCH 00/18] virtiofs: Fix various races and cleanups round 1 Miklos Szeredi
2019-09-06 10:36 ` Stefan Hajnoczi
2019-09-06 11:52 ` Miklos Szeredi
2019-09-06 12:08 ` Vivek Goyal
2019-09-06 13:55 ` Miklos Szeredi
2019-09-06 13:57 ` Michael S. Tsirkin
2019-09-06 14:11 ` Miklos Szeredi
2019-09-06 14:17 ` Michael S. Tsirkin
2019-09-08 11:53 ` [Virtio-fs] " piaojun
2019-09-09 16:14 ` Stefan Hajnoczi
2019-09-09 16:18 ` Michael S. Tsirkin
2019-09-09 23:52 ` piaojun
2019-09-06 13:37 ` Michael S. Tsirkin
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