Thanks for the information.
On 03/24/2016 07:34 PM, FNU Raghavendra Manjunath wrote:
Yes. I think the caching example mentioned by Shyam is a good example of
ESTALE error. Also User Serviceable Snapshots (USS) relies heavily on
ESTALE errors. Because the files/directories from the snapshots are
assigned a virtual gfid on the fly when being looked up. If those inodes
are purged out of the inode table due to lru list becoming full, then a
access to that gfid from the client, will make snapview-server send
ESTALE and either fuse (I think our fuse xlator does a revalidate upon
getting ESTALE) or NFS client can revalidate via path based resolution.
So wouldn't it be wrong not to send ESTALE to NFS-clients and map it to
ENOENT, as was intended in the original mail.
NFSv3 rfc [1] mentions that NFS3ERR_STALE is a valid error for REMOVE fop.
Also (at least in gfapi) the resolve code path doesn't seem to be
honoring ESTALE errors - glfs_resolve_component(..),
glfs_refresh_inode_safe(..) etc.. Do we need to fix them?
Thanks,
Soumya
[1] https://www.ietf.org/rfc/rfc1813.txt (section# 3.3.12)
Regards,
Raghavendra
On Thu, Mar 24, 2016 at 9:51 AM, Shyam <srangana@xxxxxxxxxx
<mailto:srangana@xxxxxxxxxx>> wrote:
On 03/23/2016 12:07 PM, Ravishankar N wrote:
On 03/23/2016 09:16 PM, Soumya Koduri wrote:
If it occurs only when the file/dir is not actually present
at the
back-end, shouldn't we fix the server to send ENOENT then?
I never fully understood it here is the answer:
http://review.gluster.org/#/c/6318/
The intention of ESTALE is to state that the inode#/GFID is stale,
when using that for any operations. IOW, we did not find the GFID in
the backend, that does not mean the name is not present. This hence
means, if you have a pGFID+bname, try resolving with that.
For example, a client side cache can hang onto a GFID for a bname,
but another client could have, in the interim, unlinked the bname
and create a new file there.
A presence test using GFID by the client that cached the result the
first time, is an ESTALE. But a resolution based on pGFID+bname
again by the same client would be a success.
By extension, a GFID based resolution, when not really present in
the backend will return ESTALE, it could very well mean ENOENT, but
that has to be determined by the client again, if possible.
See "A10. What does it mean when my application fails because of an
ESTALE error?" for NFS here [1] and [2] (there maybe better sources
for this information)
[1] http://nfs.sourceforge.net/
[2] https://lwn.net/Articles/272684/
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