kbuild test robot reported:
fs/built-in.o: In function `pnfs_report_layoutstat':
>> (.text+0x151a1c): undefined reference to `nfs42_proc_layoutstats_generic'
Reported-by: kbuild test robot <fengguang.wu@intel.com>
Signed-off-by: Peng Tao <tao.peng@primarydata.com>
Signed-off-by: Trond Myklebust <trond.myklebust@primarydata.com>
Highlights include:
Stable patches:
- Fix a regression in /proc/self/mountstats
- Fix the pNFS flexfiles O_DIRECT support
- Fix high load average due to callback thread sleeping
Bugfixes:
- Various patches to fix the pNFS layoutcommit support
- Do not cache pNFS deviceids unless server notifications are enabled
- Fix a SUNRPC transport reconnection regression
- make debugfs file creation failure non-fatal in SUNRPC
- Another fix for circular directory warnings on NFSv4 "junctioned" mountpoints
- Fix locking around NFSv4.2 fallocate() support
- Truncating NFSv4 file opens should also sync O_DIRECT writes
- Prevent infinite loop in rpcrdma_ep_create()
Features:
- Various improvements to the RDMA transport code's handling of memory
registration
- Various code cleanups
-----BEGIN PGP SIGNATURE-----
Version: GnuPG v1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=j5dP
-----END PGP SIGNATURE-----
Merge tag 'nfs-for-4.1-1' of git://git.linux-nfs.org/projects/trondmy/linux-nfs
Pull NFS client updates from Trond Myklebust:
"Another set of mainly bugfixes and a couple of cleanups. No new
functionality in this round.
Highlights include:
Stable patches:
- Fix a regression in /proc/self/mountstats
- Fix the pNFS flexfiles O_DIRECT support
- Fix high load average due to callback thread sleeping
Bugfixes:
- Various patches to fix the pNFS layoutcommit support
- Do not cache pNFS deviceids unless server notifications are enabled
- Fix a SUNRPC transport reconnection regression
- make debugfs file creation failure non-fatal in SUNRPC
- Another fix for circular directory warnings on NFSv4 "junctioned"
mountpoints
- Fix locking around NFSv4.2 fallocate() support
- Truncating NFSv4 file opens should also sync O_DIRECT writes
- Prevent infinite loop in rpcrdma_ep_create()
Features:
- Various improvements to the RDMA transport code's handling of
memory registration
- Various code cleanups"
* tag 'nfs-for-4.1-1' of git://git.linux-nfs.org/projects/trondmy/linux-nfs: (55 commits)
fs/nfs: fix new compiler warning about boolean in switch
nfs: Remove unneeded casts in nfs
NFS: Don't attempt to decode missing directory entries
Revert "nfs: replace nfs_add_stats with nfs_inc_stats when add one"
NFS: Rename idmap.c to nfs4idmap.c
NFS: Move nfs_idmap.h into fs/nfs/
NFS: Remove CONFIG_NFS_V4 checks from nfs_idmap.h
NFS: Add a stub for GETDEVICELIST
nfs: remove WARN_ON_ONCE from nfs_direct_good_bytes
nfs: fix DIO good bytes calculation
nfs: Fetch MOUNTED_ON_FILEID when updating an inode
sunrpc: make debugfs file creation failure non-fatal
nfs: fix high load average due to callback thread sleeping
NFS: Reduce time spent holding the i_mutex during fallocate()
NFS: Don't zap caches on fallocate()
xprtrdma: Make rpcrdma_{un}map_one() into inline functions
xprtrdma: Handle non-SEND completions via a callout
xprtrdma: Add "open" memreg op
xprtrdma: Add "destroy MRs" memreg op
xprtrdma: Add "reset MRs" memreg op
...
that's the bulk of filesystem drivers dealing with inodes of their own
Signed-off-by: David Howells <dhowells@redhat.com>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
The LAYOUTCOMMIT operation means different things to different layout types.
For blocks and objects, it is both a data and metadata consistency operation.
For files and flexfiles, it is only a metadata consistency operation.
This patch separates out the 2 cases, allowing the files/flexfiles layout
drivers to optimise away the data consistency calls to layoutcommit.
Signed-off-by: Trond Myklebust <trond.myklebust@primarydata.com>
pnfs_set_layoutcommit() and pnfs_commit_set_layoutcommit() are 100% identical
except for the function arguments. Refactor to eliminate the difference.
Signed-off-by: Trond Myklebust <trond.myklebust@primarydata.com>
The spec says that once all layouts that reference a given deviceid
have been returned, then we are only allowed to continue to cache
the deviceid if the metadata server supports notifications.
Signed-off-by: Trond Myklebust <trond.myklebust@primarydata.com>
Use of synchronize_rcu() when unmounting and potentially freeing a lot
of deviceids is problematic. There really is no reason why we can't just
use kfree_rcu() here.
Signed-off-by: Trond Myklebust <trond.myklebust@primarydata.com>
The File Layout's filelayout_mark_request_commit() is almost the
Flex File Layout's ff_layout_mark_request_commit(). And that can
be reduced by calling into nfs_request_add_commit_list().
Signed-off-by: Tom Haynes <loghyr@primarydata.com>
Signed-off-by: Trond Myklebust <trond.myklebust@primarydata.com>
* flexfiles: (53 commits)
pnfs: lookup new lseg at lseg boundary
nfs41: .init_read and .init_write can be called with valid pg_lseg
pnfs: Update documentation on the Layout Drivers
pnfs/flexfiles: Add the FlexFile Layout Driver
nfs: count DIO good bytes correctly with mirroring
nfs41: wait for LAYOUTRETURN before retrying LAYOUTGET
nfs: add a helper to set NFS_ODIRECT_RESCHED_WRITES to direct writes
nfs41: add NFS_LAYOUT_RETRY_LAYOUTGET to layout header flags
nfs/flexfiles: send layoutreturn before freeing lseg
nfs41: introduce NFS_LAYOUT_RETURN_BEFORE_CLOSE
nfs41: allow async version layoutreturn
nfs41: add range to layoutreturn args
pnfs: allow LD to ask to resend read through pnfs
nfs: add nfs_pgio_current_mirror helper
nfs: only reset desc->pg_mirror_idx when mirroring is supported
nfs41: add a debug warning if we destroy an unempty layout
pnfs: fail comparison when bucket verifier not set
nfs: mirroring support for direct io
nfs: add mirroring support to pgio layer
pnfs: pass ds_commit_idx through the commit path
...
Conflicts:
fs/nfs/pnfs.c
fs/nfs/pnfs.h
The flexfile layout is a new layout that extends the
file layout. It is currently being drafted as a specification at
https://datatracker.ietf.org/doc/draft-ietf-nfsv4-layout-types/
Signed-off-by: Weston Andros Adamson <dros@primarydata.com>
Signed-off-by: Tom Haynes <loghyr@primarydata.com>
Signed-off-by: Tao Peng <bergwolf@primarydata.com>
Use it to indicate that LD wants to retry layoutget. LD can set
it whenever it wants the common pnfs code to return and retry
pnfs path through a new layout.
The bit gets cleared when client does a new layoutget, when client
closes the file (ROC case), or when kernel needs to evict the inode
(non-ROC case).
Signed-off-by: Peng Tao <tao.peng@primarydata.com>
When it is set, generic pnfs would try to send layoutreturn right
before last close/delegation_return regard less NFS_LAYOUT_ROC is
set or not. LD can then make sure layoutreturn is always sent
rather than being omitted.
The difference against NFS_LAYOUT_RETURN is that
NFS_LAYOUT_RETURN_BEFORE_CLOSE does not block usage of the layout so
LD can set it and expect generic layer to try pnfs path at the
same time.
Signed-off-by: Peng Tao <tao.peng@primarydata.com>
Signed-off-by: Tom Haynes <loghyr@primarydata.com>
If current IO cannot be completed due to some transient errors,
LD may want to ask generic layer to resend the request through
pnfs again.
Signed-off-by: Peng Tao <tao.peng@primarydata.com>
Signed-off-by: Tom Haynes <loghyr@primarydata.com>
Pass ds_commit_idx through the nfs commit path. It's used to select
the commit bucket when using pnfs and is ignored when not using pnfs.
Several functions had to be changed: nfs_retry_commit,
nfs_mark_request_commit, pnfs_mark_request_commit and the pnfs layout
driver .mark_request_commit functions.
Signed-off-by: Tom Haynes <loghyr@primarydata.com>
This is needed to support mirrored writes - the first write can't just
trash the lseg, we need to keep it around until all mirrors have
written.
Signed-off-by: Weston Andros Adamson <dros@primarydata.com>
And if we are to return the same type of layouts, don't bother
sending more layoutgets.
Signed-off-by: Peng Tao <tao.peng@primarydata.com>
Signed-off-by: Tom Haynes <Thomas.Haynes@primarydata.com>
It marks all matching layout segments as NFS_LSEG_LAYOUTRETURN,
which is an indicator for pnfs_put_lseg() to send layoutreturn,
and also prevents pnfs_update_layout() from using the returning
segments. Once it is set, it never gets cleared.
It also sets proper io failure bit so that pnfs path can be retried
after PNFS_LAYOUTGET_RETRY_TIMEOUT second.
Signed-off-by: Peng Tao <tao.peng@primarydata.com>
Signed-off-by: Tom Haynes <Thomas.Haynes@primarydata.com>
Per RFC 5661 Errata 3208:
| A client MAY always forget its layout state and associated
| layout stateid at any time (See also section 12.5.5.1).
| In such case, the client MUST use a non-layout stateid for the next
| LAYOUTGET operation. This will signal the server that the client has
| no more layouts on the file and its respective layout state can be
| released before issuing a new layout in response to LAYOUTGET.
In order to make such a signal unique to server, client needs to serialize
all layoutgets using non-layout stateid. We implement this by serializing
layoutgets when client has no layout segments at hand.
Signed-off-by: Peng Tao <tao.peng@primarydata.com>
Signed-off-by: Tom Haynes <Thomas.Haynes@primarydata.com>
flexfile layout may need to set such when making DS connections.
Signed-off-by: Peng Tao <tao.peng@primarydata.com>
Signed-off-by: Tom Haynes <Thomas.Haynes@primarydata.com>
They can be reused by flexfile layout as well.
Also add a code such that if read fails on one DS and
there are other DSes available to use, don't resend
through MDS but through pNFS so that client can read
from other DSes.
Reviewed-by: Jeff Layton <jlayton@primarydata.com>
Signed-off-by: Peng Tao <tao.peng@primarydata.com>
Signed-off-by: Tom Haynes <Thomas.Haynes@primarydata.com>
flexfile layout may use different auth flavor as specified by MDS.
Reviewed-by: Jeff Layton <jlayton@primarydata.com>
Signed-off-by: Peng Tao <tao.peng@primarydata.com>
Signed-off-by: Tom Haynes <Thomas.Haynes@primarydata.com>
It can be reused by flexfiles layout client.
Reviewed-by: Jeff Layton <jlayton@primarydata.com>
Signed-off-by: Peng Tao <tao.peng@primarydata.com>
Signed-off-by: Tom Haynes <Thomas.Haynes@primarydata.com>
It can be reused by flexfile layout.
Reviewed-by: Jeff Layton <jlayton@primarydata.com>
Signed-off-by: Peng Tao <tao.peng@primarydata.com>
Signed-off-by: Tom Haynes <Thomas.Haynes@primarydata.com>
Also pull nfs4_pnfs_ds_addr and nfs4_pnfs_ds to generic pnfs.
They can all be reused by flexfile layout as well.
Reviewed-by: Jeff Layton <jlayton@primarydata.com>
Signed-off-by: Peng Tao <tao.peng@primarydata.com>
Signed-off-by: Tom Haynes <Thomas.Haynes@primarydata.com>
The flexfilelayout driver will share some common code
with the filelayout driver. This set of changes refactors
that common code out to avoid any module depenencies.
Signed-off-by: Tom Haynes <loghyr@primarydata.com>
Optimise the layout return on close code by ensuring that
1) Add a check for whether we hold a layout before taking any spinlocks
2) Only take the spin lock once
3) Use nfs_state->state to speed up open file checks
Signed-off-by: Trond Myklebust <trond.myklebust@primarydata.com>
You cannot call pnfs_put_lseg_async() more than once per lseg, so it
is really an inappropriate way to deal with a refcount issue.
Instead, replace it with a function that decrements the refcount, and
puts the final 'free' operation (which is incompatible with locks) on
the workqueue.
Cc: Weston Andros Adamson <dros@primarydata.com>
Fixes: e6cf82d1830f: pnfs: add pnfs_put_lseg_async
Signed-off-by: Trond Myklebust <trond.myklebust@primarydata.com>
nfs4_insert_deviceid_node() was removed in 661373b13d
Signed-off-by: Tom Haynes <loghyr@primarydata.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Trond Myklebust <trond.myklebust@primarydata.com>
Both blocks layout and objects layout want to use it to avoid CB_LAYOUTRECALL
but that should only happen if client is doing truncation to a smaller size.
For other cases, we let server decide if it wants to recall client's layouts.
Change PNFS_LAYOUTRET_ON_SETATTR to follow the logic and not to send
layoutreturn unnecessarily.
Cc: Christoph Hellwig <hch@lst.de>
Cc: Boaz Harrosh <boaz@plexistor.com>
Signed-off-by: Peng Tao <tao.peng@primarydata.com>
Signed-off-by: Trond Myklebust <trond.myklebust@primarydata.com>
The current GETDEVICELIST implementation is buggy in that it doesn't handle
cursors correctly, and in that it returns an error if the server returns
NFSERR_NOTSUPP. Given that there is no actual need for GETDEVICELIST,
it has various issues and might get removed for NFSv4.2 stop using it in
the blocklayout driver, and thus the Linux NFS client as whole.
Signed-off-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Trond Myklebust <trond.myklebust@primarydata.com>
This will be used by the block layout driver when splitting extents.
Signed-off-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Trond Myklebust <trond.myklebust@primarydata.com>
At a simple helper to issue a GETDEVICELIST operation and pre-load
the device id cache based on the result.
Signed-off-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Trond Myklebust <trond.myklebust@primarydata.com>
Add support to the common pNFS core to issue GETDEVICEINFO calls on
a device ID cache miss. The code is taken from the well debugged
file layout implementation and calls out to the layoutdriver through
a new alloc_deviceid_node method. The calling conventions for
nfs4_find_get_deviceid are changed so that all information needed to
send a GETDEVICEINFO request is passed to the common code.
Signed-off-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Trond Myklebust <trond.myklebust@primarydata.com>
If a layout driver keeps per-inode state outside of the layout segments it
needs to be notified of any layout returns or recalls on an inode, and not
just about the freeing of layout segments. Add a method to acomplish this,
which will allow the block layout driver to handle the case of truncated
and re-expanded files properly.
Signed-off-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Trond Myklebust <trond.myklebust@primarydata.com>
Like all block based filesystems, the pNFS block layout driver can't read
or write at a byte granularity and thus has to perform read-modify-write
cycles on writes smaller than this granularity.
Add a flag so that the core NFS code always reads a whole page when
starting a smaller write, so that we can do it in the place where the VFS
expects it instead of doing in very deadlock prone way in the writeback
handler.
Note that in theory we could do less than page size reads here for disks
that have a smaller sector size which are served by a server with a smaller
pnfs block size. But so far that doesn't seem like a worthwhile
optimization.
Signed-off-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Trond Myklebust <trond.myklebust@primarydata.com>
Currently there is no XDR buffer space allocated for the per-layout driver
layoutcommit payload, which leads to server buffer overflows in the
blocklayout driver even under simple workloads. As we can't do per-layout
sizes for XDR operations we'll have to splice a previously encoded list
of pages into the XDR stream, similar to how we handle ACL buffers.
Signed-off-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Trond Myklebust <trond.myklebust@primarydata.com>
After we issued a layoutreturn operations the may free the layout stateid
and will thus cause bad stateid error when the client uses it again.
We currently try to avoid this case by chosing the open stateid if not
lsegs are present for this inode. But various places can hold refererence
on lsegs and thus cause the list not to be empty shortly after a layout
return. Add an explicit flag to mark the current layout stateid invalid
and force usage of the openstateid after we did a full file layoutreturn.
Signed-off-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Trond Myklebust <trond.myklebust@primarydata.com>
Track lwb in nfs_commit_data so that we can use it to setup
layoutcommit in commit_done callback.
Signed-off-by: Peng Tao <tao.peng@primarydata.com>
Signed-off-by: Trond Myklebust <trond.myklebust@primarydata.com>
This is useful when lsegs need to be released while holding locks.
Signed-off-by: Weston Andros Adamson <dros@primarydata.com>
Signed-off-by: Trond Myklebust <trond.myklebust@primarydata.com>
nfs_page_find_head_request_locked looks through the regular nfs commit lists
when the page is swapped out, but doesn't look through the pnfs commit lists.
I'm not sure if anyone has hit any issues caused by this.
Suggested-by: Peng Tao <tao.peng@primarydata.com>
Signed-off-by: Weston Andros Adamson <dros@primarydata.com>
Signed-off-by: Trond Myklebust <trond.myklebust@primarydata.com>
Clean up pnfs_read_done_resend_to_mds and pnfs_write_done_resend_to_mds:
- instead of passing all arguments from a nfs_pgio_header, just pass the header
- share the common code
Reviewed-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Weston Andros Adamson <dros@primarydata.com>
Signed-off-by: Trond Myklebust <trond.myklebust@primarydata.com>
struct nfs_pgio_data only exists as a member of nfs_pgio_header, but is
passed around everywhere, because there used to be multiple _data structs
per _header. Many of these functions then use the _data to find a pointer
to the _header. This patch cleans this up by merging the nfs_pgio_data
structure into nfs_pgio_header and passing nfs_pgio_header around instead.
Reviewed-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Weston Andros Adamson <dros@primarydata.com>
Signed-off-by: Trond Myklebust <trond.myklebust@primarydata.com>
Highlights include:
- Massive cleanup of the NFS read/write code by Anna and Dros
- Support multiple NFS read/write requests per page in order to deal with
non-page aligned pNFS striping. Also cleans up the r/wsize < page size
code nicely.
- stable fix for ensuring inode is declared uptodate only after all the
attributes have been checked.
- stable fix for a kernel Oops when remounting
- NFS over RDMA client fixes
- move the pNFS files layout driver into its own subdirectory
-----BEGIN PGP SIGNATURE-----
Version: GnuPG v1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=OyXR
-----END PGP SIGNATURE-----
Merge tag 'nfs-for-3.16-1' of git://git.linux-nfs.org/projects/trondmy/linux-nfs
Pull NFS client updates from Trond Myklebust:
"Highlights include:
- massive cleanup of the NFS read/write code by Anna and Dros
- support multiple NFS read/write requests per page in order to deal
with non-page aligned pNFS striping. Also cleans up the r/wsize <
page size code nicely.
- stable fix for ensuring inode is declared uptodate only after all
the attributes have been checked.
- stable fix for a kernel Oops when remounting
- NFS over RDMA client fixes
- move the pNFS files layout driver into its own subdirectory"
* tag 'nfs-for-3.16-1' of git://git.linux-nfs.org/projects/trondmy/linux-nfs: (79 commits)
NFS: populate ->net in mount data when remounting
pnfs: fix lockup caused by pnfs_generic_pg_test
NFSv4.1: Fix typo in dprintk
NFSv4.1: Comment is now wrong and redundant to code
NFS: Use raw_write_seqcount_begin/end int nfs4_reclaim_open_state
xprtrdma: Disconnect on registration failure
xprtrdma: Remove BUG_ON() call sites
xprtrdma: Avoid deadlock when credit window is reset
SUNRPC: Move congestion window constants to header file
xprtrdma: Reset connection timeout after successful reconnect
xprtrdma: Use macros for reconnection timeout constants
xprtrdma: Allocate missing pagelist
xprtrdma: Remove Tavor MTU setting
xprtrdma: Ensure ia->ri_id->qp is not NULL when reconnecting
xprtrdma: Reduce the number of hardway buffer allocations
xprtrdma: Limit work done by completion handler
xprtrmda: Reduce calls to ib_poll_cq() in completion handlers
xprtrmda: Reduce lock contention in completion handlers
xprtrdma: Split the completion queue
xprtrdma: Make rpcrdma_ep_destroy() return void
...
This is a step toward allowing pg_test to inform the the
coalescing code to reduce the size of requests so they may fit in
whatever scheme the pg_test callback wants to define.
For now, just return the size of the request if there is space, or 0
if there is not. This shouldn't change any behavior as it acts
the same as when the pg_test functions returned bool.
Signed-off-by: Weston Andros Adamson <dros@primarydata.com>
Signed-off-by: Trond Myklebust <trond.myklebust@primarydata.com>
At this point, the only difference between nfs_read_data and
nfs_write_data is the write verifier.
Signed-off-by: Anna Schumaker <Anna.Schumaker@Netapp.com>
Signed-off-by: Trond Myklebust <trond.myklebust@primarydata.com>