Re: [REGRESSION] nfs client: Read-only file system (2.6.19-rc1,2)

[Jiri Slaby <jirislaby@gmail.com>]

Trond Myklebust wrote:
> I'll bet that you have always had a subdirectory of the exact same
> filesystem mounted somewhere else ro, right?

Yup, exactly: /usr -ro and /home -rw on the same (hda3) partition.

> The new NFS mount code will put those in the same superblock, and
> whichever directory gets mounted first will determine whether or not the
> superblock is marked as read-only.
> Basically, NFS is now doing the exact same thing that local filesystems
> have been doing all the time: if it is on the same disk, then it is all
> represented by the same superblock. OTOH, if your server is exporting
> more than one partition, then different partitions will be represented
> by different superblocks.
> We need to do this for the same reason that local filesystems do it: it
> is the only way to ensure cache consistency. Otherwise, if you make
> changes to a file that happens to be mounted in more than one place,
> then you will see inconsistent results on the other mountpoints.

thanks for clarification,
--
http://www.fi.muni.cz/~xslaby/            Jiri Slaby
faculty of informatics, masaryk university, brno, cz
e-mail: jirislaby gmail com, gpg pubkey fingerprint:
B674 9967 0407 CE62 ACC8  22A0 32CC 55C3 39D4 7A7E
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