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authorMartin Brandenburg <martin@omnibond.com>2017-04-06 18:11:00 -0400
committerLinus Torvalds <torvalds@linux-foundation.org>2017-04-07 13:41:22 -0700
commitcefdc26e86728812aea54248a534fd4a5da2a43d (patch)
treec93ee54be4e4502ccee2344070438aea5bac2c6a /fs/orangefs/super.c
parentc2eb7beac7638566f20f705cee48e0a3cd4e48b7 (diff)
orangefs: move features validation to fix filesystem hang
Without this fix (and another to the userspace component itself described later), the kernel will be unable to process any OrangeFS requests after the userspace component is restarted (due to a crash or at the administrator's behest). The bug here is that inside orangefs_remount, the orangefs_request_mutex is locked. When the userspace component restarts while the filesystem is mounted, it sends a ORANGEFS_DEV_REMOUNT_ALL ioctl to the device, which causes the kernel to send it a few requests aimed at synchronizing the state between the two. While this is happening the orangefs_request_mutex is locked to prevent any other requests going through. This is only half of the bugfix. The other half is in the userspace component which outright ignores(!) requests made before it considers the filesystem remounted, which is after the ioctl returns. Of course the ioctl doesn't return until after the userspace component responds to the request it ignores. The userspace component has been changed to allow ORANGEFS_VFS_OP_FEATURES regardless of the mount status. Mike Marshall says: "I've tested this patch against the fixed userspace part. This patch is real important, I hope it can make it into 4.11... Here's what happens when the userspace daemon is restarted, without the patch: ============================================= [ INFO: possible recursive locking detected ] [ 4.10.0-00007-ge98bdb3 #1 Not tainted ] --------------------------------------------- pvfs2-client-co/29032 is trying to acquire lock: (orangefs_request_mutex){+.+.+.}, at: service_operation+0x3c7/0x7b0 [orangefs] but task is already holding lock: (orangefs_request_mutex){+.+.+.}, at: dispatch_ioctl_command+0x1bf/0x330 [orangefs] CPU: 0 PID: 29032 Comm: pvfs2-client-co Not tainted 4.10.0-00007-ge98bdb3 #1 Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.9.3-1.fc25 04/01/2014 Call Trace: __lock_acquire+0x7eb/0x1290 lock_acquire+0xe8/0x1d0 mutex_lock_killable_nested+0x6f/0x6e0 service_operation+0x3c7/0x7b0 [orangefs] orangefs_remount+0xea/0x150 [orangefs] dispatch_ioctl_command+0x227/0x330 [orangefs] orangefs_devreq_ioctl+0x29/0x70 [orangefs] do_vfs_ioctl+0xa3/0x6e0 SyS_ioctl+0x79/0x90" Signed-off-by: Martin Brandenburg <martin@omnibond.com> Acked-by: Mike Marshall <hubcap@omnibond.com> Cc: stable@vger.kernel.org Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'fs/orangefs/super.c')
-rw-r--r--fs/orangefs/super.c9
1 files changed, 7 insertions, 2 deletions
diff --git a/fs/orangefs/super.c b/fs/orangefs/super.c
index 67c24351a67f..cd261c8de53a 100644
--- a/fs/orangefs/super.c
+++ b/fs/orangefs/super.c
@@ -263,8 +263,13 @@ int orangefs_remount(struct orangefs_sb_info_s *orangefs_sb)
if (!new_op)
return -ENOMEM;
new_op->upcall.req.features.features = 0;
- ret = service_operation(new_op, "orangefs_features", 0);
- orangefs_features = new_op->downcall.resp.features.features;
+ ret = service_operation(new_op, "orangefs_features",
+ ORANGEFS_OP_PRIORITY | ORANGEFS_OP_NO_MUTEX);
+ if (!ret)
+ orangefs_features =
+ new_op->downcall.resp.features.features;
+ else
+ orangefs_features = 0;
op_release(new_op);
} else {
orangefs_features = 0;

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