Alexander Viro wrote:
> OK, folks, I've got _something_ that looks more or less like
> union-mount in a working state.
Cool !
> A) suppose we have a bunch of filesystems union-mounted on
> /foo/bar. We do chdir("/foo/bar"), what should become busy? Variants:
> mountpoint, first element, last element, all of them.
Do you mean the general case, if pathU into a unionfs corresponds to
path1...pathN in unionfs elements, what should become busy, or specificly
only mount points ? For the general case, I'd say as little as possible,
e.g. if the unionfs can collapse enough state into its own structures to
to provide meaningful semantics (including things like ..), it shouldn't
keep its elements busy.
> C) we start with the normal mount and union-mount something else.
> Question: what is the desired result (almost definitely the set of old and
> new mounted stuff) and who should become busy?
Hmm, how do you construct a unionfs ? By layering elements on top of an
existing directory ? Or by mounting the whole package ?
> D) In the cases above, what do we want to get from stat(2)?
st_nlink = `expr 1 + \`find . -type d -maxdepth 1 | wc -l\``
Was this the question ? ;-)
> Frankly, I'm sorely tempted to say that cd to mountpoint always
> makes the mountpoint busy and leaves the mounted fs alone.
Seems that this could cause problems with pivot_root. Or would
cd /dir be different from cd /dir. ? (Nasty, if you ask me.)
- Werner
-- _________________________________________________________________________ / Werner Almesberger, ICA, EPFL, CH werner.almesberger@ica.epfl.ch / /_IN_N_032__Tel_+41_21_693_6621__Fax_+41_21_693_6610_____________________/- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.rutgers.edu Please read the FAQ at http://www.tux.org/lkml/
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