[PATCH 1/6] xstat: Add a pair of system calls to make extended file stats available
adilger at dilger.ca
Thu Apr 19 17:36:32 MDT 2012
On 2012-04-19, at 8:06 AM, David Howells wrote:
> Add a pair of system calls to make extended file stats available,
> including file creation time, inode version and data version where available through the underlying filesystem.
> The idea was initially proposed as a set of xattrs that could be
> retrieved with getxattr(), but the general preferance proved to be
> for new syscalls with an extended stat structure.
I would comment that it was the opposite. It was originally a
stat()-like extension that degraded into a messy getxattr() mess.
> (2) Lightweight stat: Ask for just those details of interest, and
> allow a netfs (such as NFS) to approximate anything not of
> interest, possibly without going to the server [Trond Myklebust,
> Ulrich Drepper].
This was my original motivation for this functionality, so you can
put my name here also.
> The fields in struct xstat come in a number of classes:
> (0) st_dev, st_blksize, st_information.
> These are local data and are always available.
For the extra two bits it would cost us, I don't think st_blksize
and st_information should always be returned. st_blksize may be
variable for a distributed filesystem, and some of the fields in
st_information (offline) may not be free to access either.
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