This supports client read caching. A Level 1 or exclusive oplock allows a client to open a stream for exclusive access and allows the client to perform arbitrary buffering. This supports client read caching and write caching. A Batch oplock also exclusive allows a client to keep a stream open on the server even though the local accessor on the client machine has closed the stream.
This supports scenarios where the client needs to repeatedly open and close the same file, such as during batch script execution. This supports client read caching, write caching, and handle caching.
A Filter oplock also exclusive allows applications and file system filters including minifilters , which open and read stream data, a way to "back out" when other applications, clients, or both try to access the same stream. A Read R oplock shared indicates that there are multiple readers of a stream and no writers. A Read-Handle RH oplock shared indicates that there are multiple readers of a stream, no writers, and that a client can keep a stream open on the server even though the local accessor on the client machine has closed the stream.
This supports client read caching and handle caching. A Read-Write RW oplock exclusive allows a client to open a stream for exclusive access and allows the client to perform arbitrary buffering. A Read-Write-Handle RWH oplock exclusive allows a client to keep a stream open on the server even though the local accessor on the client machine has closed the stream. The Filter oplock was added in Windows The following sections list each operation and describe what triggers an oplock break, what determines the level to which the oplock breaks, and whether an acknowledgment of the break is required:.
Note The above listed per-operation topics describe the details of when a break of a Read-Handle oplock results in the pending of the operation that broke the oplock. Skip to main content. This browser is no longer supported. Download Microsoft Edge More info. Contents Exit focus mode. Please rate your experience Yes No. Any additional feedback? Breaking Oplock. Basic concept. Redirector FSD.
Cache Manager. Protocol driver. Local FSD. Server FSD. User mode. Kernel mode. Filter Driver. Client side. Server side. We observe. Oplock type. Filter Oplock. How to require filter oplock. But if it performs another Create on the same file, and causes the server to issue a break notification, that is where the problems start.
Sometimes the client will receive the break notification, process it, and respond by releasing its oplock. When that happens, my server will respond to the break acknowledgement, and grant the new create. Everyone in happy. Other times, however, the client will receive the break and seemingly just ignore it. What is more, the same types of tasks being done on the client consistently fail or succeed. After the oplock timer expires, I have the server return an error to the second create request since the oplock couldn't be broken.
The client will then close the original file, and repeat the second open, and is able to complete the task it was attempting. I am sure that all the SMB2 packets are being received because I ran a wireshark trace directly from the client. I have been testing with Windows Vista, 7, and 8 clients, and have observed the same behavior in all three places. I tried looking for evidence of others running into this problem but did not find anything that helped me to figure out what is going on with this.
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