• M
    orangefs: move features validation to fix filesystem hang · cefdc26e
    Martin Brandenburg 提交于
    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-ge98bdb30 #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-ge98bdb30 #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: NMartin Brandenburg <martin@omnibond.com>
    Acked-by: NMike Marshall <hubcap@omnibond.com>
    Cc: stable@vger.kernel.org
    Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>
    cefdc26e
super.c 15.5 KB