linux.git/fs/nfs/flexfilelayout/flexfilelayoutdev.c, branch v4.8

pNFS/flexfiles: Fix an Oopsable condition when connection to the DS fails

2016-08-29T19:21:16+00:00

If the attempt to connect to a DS fails inside ff_layout_pg_init_read or
ff_layout_pg_init_write, then we currently end up clearing the layout
segment carried by the struct nfs_pageio_descriptor, causing an Oops
when we later call into ff_layout_read_pagelist/ff_layout_write_pagelist.

The fix is to ensure we return the layout and then retry.

Fixes: 446ca2195303 ("pNFS/flexfiles: When initing reads or writes, we...")
Cc: stable@vger.kernel.org # v4.7+
Signed-off-by: Trond Myklebust

pNFS/flexfiles: Set reasonable default retrans values for the data channel

2016-08-16T15:16:19+00:00

Prior to this patch, the retrans value was set at 5, meaning that we
could see a maximum retransmission timeout value of more than 6 minutes.
That's a tad high for NFSv3 where the protocol does allow the server to
drop requests at any time.

Since this is a data channel, let's just set retrans to 0, and the default
timeout to 60s. The user can continue to adjust these defaults using the
dataserver_retrans and dataserver_timeo module parameters.

Signed-off-by: Trond Myklebust

nfs/flexfiles: Helper function to detect FF_FLAGS_NO_READ_IO

2016-05-25T17:35:20+00:00

The mds can inform the client not to use the IOMODE_RW layout
segment for doing READs. I.e., it is basically a
IOMODE_WRITE layout segment.

It would do this to not interfere with the WRITEs.

Signed-off-by: Tom Haynes 
Signed-off-by: Anna Schumaker

flexfiles: add kerneldoc header to nfs4_ff_layout_prepare_ds

2016-05-17T19:48:11+00:00

Signed-off-by: Jeff Layton 
Signed-off-by: Anna Schumaker

flexfiles: remove pointless setting of NFS_LAYOUT_RETURN_REQUESTED

2016-05-17T19:48:11+00:00

Setting just the NFS_LAYOUT_RETURN_REQUESTED flag doesn't do anything,
unless there are lsegs that are also being marked for return. At the
point where that happens this flag is also set, so these set_bit calls
don't do anything useful.

Signed-off-by: Jeff Layton 
Signed-off-by: Anna Schumaker

pNFS/flexfiles: When checking for available DSes, conditionally check for MDS io

2016-05-17T19:48:08+00:00

Whenever we check to see if we have the needed number of DSes for the
action, we may also have to check to see whether IO is allowed to go to
the MDS or not.

[jlayton: fix merge conflict due to lack of localio patches here]

Signed-off-by: Tom Haynes 
Signed-off-by: Jeff Layton 
Signed-off-by: Anna Schumaker

NFSv4: Label stateids with the type

2016-05-17T19:48:06+00:00

In order to more easily distinguish what kind of stateid we are dealing
with, introduce a type that can be used to label the stateid structure.

The label will be useful both for debugging, but also when dealing with
operations like SETATTR, READ and WRITE that can take several different
types of stateid as arguments.

Signed-off-by: Trond Myklebust 
Signed-off-by: Anna Schumaker

nfs: have flexfiles mirror keep creds for both ro and rw layouts

2016-05-09T13:05:40+00:00

A mirror can be shared between multiple layouts, even with different
iomodes. That makes stats gathering simpler, but it causes a problem
when we get different creds in READ vs. RW layouts.

The current code drops the newer credentials onto the floor when this
occurs. That's problematic when you fetch a READ layout first, and then
a RW. If the READ layout doesn't have the correct creds to do a write,
then writes will fail.

We could just overwrite the READ credentials with the RW ones, but that
would break the ability for the server to fence the layout for reads if
things go awry. We need to be able to revert to the earlier READ creds
if the RW layout is returned afterward.

The simplest fix is to just keep two sets of creds per mirror. One for
READ layouts and one for RW, and then use the appropriate set depending
on the iomode of the layout segment.

Also fix up some RCU nits that sparse found.

Signed-off-by: Jeff Layton 
Signed-off-by: Anna Schumaker

nfs: get a reference to the credential in ff_layout_alloc_lseg

2016-05-09T13:05:40+00:00

We're just as likely to have allocation problems here as we would if we
delay looking up the credential like we currently do. Fix the code to
get a rpc_cred reference early, as soon as the mirror is set up.

This allows us to eliminate the mirror early if there is a problem
getting an rpc credential. This also allows us to drop the uid/gid
from the layout_mirror struct as well.

In the event that we find an existing mirror where this one would go, we
swap in the new creds unconditionally, and drop the reference to the old
one.

Note that the old ff_layout_update_mirror_cred function wouldn't set
this pointer unless the DS version was 3, but we don't know what the DS
version is at this point. I'm a little unclear on why it did that as you
still need creds to talk to v4 servers as well. I have the code set
it regardless of the DS version here.

Also note the change to using generic creds instead of calling
lookup_cred directly. With that change, we also need to populate the
group_info pointer in the acred as some functions expect that to never
be NULL. Instead of allocating one every time however, we can allocate
one when the module is loaded and share it since the group_info is
refcounted.

Signed-off-by: Jeff Layton 
Signed-off-by: Anna Schumaker

nfs: have ff_layout_get_ds_cred take a reference to the cred

2016-05-09T13:05:40+00:00

In later patches, we're going to want to allow the creds to be updated
when we get a new layout with updated creds. Have this function take
a reference to the cred that is later put once the call has been
dispatched.

Also, prepare for this change by ensuring we follow RCU rules when
getting a reference to the cred as well.

Signed-off-by: Jeff Layton 
Signed-off-by: Anna Schumaker