On Fri, 2013-01-25 at 16:09 +0100, Sebastian Riemer wrote:

On 20.01.2013 19:44, Ben Hutchings wrote:

quoted

# Call fsync()
python -c "import os; os.fsync(os.open('/dev/md0', os.O_RDWR))"

--- END ---

I assume that the sync request should be filtered out at some point
before this assertion is made, since there can be nothing to sync.

I wrote a test case in C. It gets SIGSEGV upon fsync. When making the
rdevs below also read-only the MD device can't be stopped anymore as it
thinks that there is still active IO.

The attached patch should fix it. Please confirm.

I applied this on top of 3.2.37 and it certainly fixes the crash.
However I wonder whether fsync() should fail or should immediately
succeed.  I don't know whether the installer expects it to succeed.

Ben.

We have to return a
completion without incrementing the active IO count. Error code -EROFS
seems to be suited best.

But the libc fsync gets -EIO anyway:
Input/output error

Any objection?

Cheers,
Sebastian

-- 
Ben Hutchings
Any smoothly functioning technology is indistinguishable from a rigged demo.