Re: Bad FS behavior w/ testcase

From: Stephen C. Tweedie (sct@redhat.com)
Date: Wed Mar 29 2000 - 10:55:43 EST


Hi,

On Wed, Mar 29, 2000 at 04:33:43PM +0200, Dr. Michael Weller wrote:
>
> Well, yes. But he said the write back was caused by the close caused by
> the exit.

No, the write back is caused by the implicit munmap() of the mapped
virtual memory region. Just closing a file handle doesn't cause any
activity in the file itself, usually (although there can be exceptions:
NFS flushes data out to the network on close, for example).

> In theory, the close syscall could check if only 1 reference
> to the inode was left and if so discard all changes. Now, I don't know
> how difficult that would be, so I won't say someone should add it.

It's nothing to do with the close. By the time the file handle has
been finally closed, we have already done the VM writeback operation.

--Stephen

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