Trond Myklebust wrote:
It might also be nice to put the above test in a little inlined helper
function (called nfs_want_read_modify_write() ?).
Good suggestion.
So, a number of questions spring to mind:
1. What if we're extending the file? We might not need to read the
page at all in that case (see nfs_write_end()).
Yup.
2. What if the page is already dirty or is carrying an uncommitted
unstable write?
Yup.
3. We might want to try to avoid looping more than once here. If
the kernel is very low on memory, we might just want to write
out the data rather than read the page and risk having the VM
eject it before we can dirty it.
Yup.
4. Should we be starting an async readahead on the next page?
Single page sized reads can be a nuisance too, if you are
writing huge amounts of data.
This one is tough. It sounds good, but seems difficult to implement.
I think that this could be viewed as an optimization.
ps
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