Messages in this thread | | | Date | Thu, 5 Aug 1999 05:27:20 +0200 | From | Jamie Lokier <> | Subject | 2.3 SMP overlapping writes and NFS |
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If two processes write to an overlapping region of a file at the same time, current 2.3 SMP kernels may mix the data from the two writes. This is a consequence of the 2.3 SMP scalability changes, am I right?
I just spotted this in the NFSv2 spec (rfc1094)
Writes "data" beginning "offset" bytes from the beginning of "file". The first byte of the file is at offset zero. If the reply "status" is NFS_OK, then the reply "attributes" contains the attributes of the file after the write has completed. The write operation is atomic. ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ Data from this "WRITE" will not be mixed with data from another ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ client's "WRITE". ^^^^^^^^^^^^^^^^
NFSv2's requirements are stricter -- so I guess knfsd has to handle this by locking the inode during an NFSv2 write. Is this done and does anyone care?
I don't see any similar wording in NFSv3 (rfc1813).
-- Jamie
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