Preparation for the patch that de-serialises O_DIRECT reads and
writes.
Signed-off-by: NTrond Myklebust <trond.myklebust@primarydata.com>

Signed-off-by: NTrond Myklebust <trond.myklebust@primarydata.com>

While COMMIT has the potential to free up a lot of memory that is being
taken by unstable writes, it isn't guaranteed to free up this particular
page. Also, calling fsync() on the server is expensive and so we want to
do it in a more controlled fashion, rather than have it triggered at
random by the VM.
Signed-off-by: NTrond Myklebust <trond.myklebust@primarydata.com>

Commits are no longer required to be serialised.
Signed-off-by: NTrond Myklebust <trond.myklebust@primarydata.com>

filemap_datawrite() and friends already deal just fine with livelock.
Signed-off-by: NTrond Myklebust <trond.myklebust@primarydata.com>

Unless the user is using file locking, we must assume close-to-open
cache consistency when the file is open for writing. Adjust the
caching algorithm so that it does not clear the cache on out-of-order
writes and/or attribute revalidations.
Signed-off-by: NTrond Myklebust <trond.myklebust@primarydata.com>

Including blkdev_direct_IO and dax_do_io.  It has to be ki_pos to actually
work, so eliminate the superflous argument.
Signed-off-by: NChristoph Hellwig <hch@lst.de>
Signed-off-by: NAl Viro <viro@zeniv.linux.org.uk>

PAGE_CACHE_{SIZE,SHIFT,MASK,ALIGN} macros were introduced *long* time
ago with promise that one day it will be possible to implement page
cache with bigger chunks than PAGE_SIZE.

This promise never materialized.  And unlikely will.

We have many places where PAGE_CACHE_SIZE assumed to be equal to
PAGE_SIZE.  And it's constant source of confusion on whether
PAGE_CACHE_* or PAGE_* constant should be used in a particular case,
especially on the border between fs and mm.

Global switching to PAGE_CACHE_SIZE != PAGE_SIZE would cause to much
breakage to be doable.

Let's stop pretending that pages in page cache are special.  They are
not.

The changes are pretty straight-forward:

 - <foo> << (PAGE_CACHE_SHIFT - PAGE_SHIFT) -> <foo>;

 - <foo> >> (PAGE_CACHE_SHIFT - PAGE_SHIFT) -> <foo>;

 - PAGE_CACHE_{SIZE,SHIFT,MASK,ALIGN} -> PAGE_{SIZE,SHIFT,MASK,ALIGN};

 - page_cache_get() -> get_page();

 - page_cache_release() -> put_page();

This patch contains automated changes generated with coccinelle using
script below.  For some reason, coccinelle doesn't patch header files.
I've called spatch for them manually.

The only adjustment after coccinelle is revert of changes to
PAGE_CAHCE_ALIGN definition: we are going to drop it later.

There are few places in the code where coccinelle didn't reach.  I'll
fix them manually in a separate patch.  Comments and documentation also
will be addressed with the separate patch.

virtual patch

@@
expression E;
@@
- E << (PAGE_CACHE_SHIFT - PAGE_SHIFT)
+ E

@@
expression E;
@@
- E >> (PAGE_CACHE_SHIFT - PAGE_SHIFT)
+ E

@@
@@
- PAGE_CACHE_SHIFT
+ PAGE_SHIFT

@@
@@
- PAGE_CACHE_SIZE
+ PAGE_SIZE

@@
@@
- PAGE_CACHE_MASK
+ PAGE_MASK

@@
expression E;
@@
- PAGE_CACHE_ALIGN(E)
+ PAGE_ALIGN(E)

@@
expression E;
@@
- page_cache_get(E)
+ get_page(E)

@@
expression E;
@@
- page_cache_release(E)
+ put_page(E)
Signed-off-by: NKirill A. Shutemov <kirill.shutemov@linux.intel.com>
Acked-by: NMichal Hocko <mhocko@suse.com>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

Just call inode_dio_wait directly instead of through a pointless wrapper.
Signed-off-by: NChristoph Hellwig <hch@lst.de>
Signed-off-by: NTrond Myklebust <trond.myklebust@primarydata.com>

The only difference to nfs_file_fsync is the call to pnfs_sync_inode.  But
pnfs_sync_inode is just an inline that calls a pNFS layout driver method
if CONFIG_PNFS is designed, and thus can be called just fine from the core
NFS module.
Signed-off-by: NChristoph Hellwig <hch@lst.de>
Signed-off-by: NTrond Myklebust <trond.myklebust@primarydata.com>

parallel to mutex_{lock,unlock,trylock,is_locked,lock_nested},
inode_foo(inode) being mutex_foo(&inode->i_mutex).

Please, use those for access to ->i_mutex; over the coming cycle
->i_mutex will become rwsem, with ->lookup() done with it held
only shared.
Signed-off-by: NAl Viro <viro@zeniv.linux.org.uk>

The use of wait_on_atomic_t() for waiting on I/O to complete before
unlocking allows us to git rid of the NFS_IO_INPROGRESS flag, and thus the
nfs_iocounter's flags member, and finally the nfs_iocounter altogether.
The count of I/O is moved to the lock context, and the counter
increment/decrement functions become simple enough to open-code.
Signed-off-by: NBenjamin Coddington <bcodding@redhat.com>
[Trond: Fix up conflict with existing function nfs_wait_atomic_killable()]
Signed-off-by: NTrond Myklebust <trond.myklebust@primarydata.com>

Allow synchronous RPC calls to wait for pending RPC calls to finish,
but also allow asynchronous ones to just fire off another commit.

With this patch, the xfstests generic/074 test completes in 226s
instead of 242s
Signed-off-by: NTrond Myklebust <trond.myklebust@primarydata.com>

Instead of dropping pages when write fails, only do it when
we get fatal failure in launder_page write back.
Signed-off-by: NPeng Tao <tao.peng@primarydata.com>
Signed-off-by: NTrond Myklebust <trond.myklebust@primarydata.com>

mm, page_alloc: distinguish between being unable to sleep, unwilling to sleep and avoiding waking kswapd

__GFP_WAIT has been used to identify atomic context in callers that hold
spinlocks or are in interrupts.  They are expected to be high priority and
have access one of two watermarks lower than "min" which can be referred
to as the "atomic reserve".  __GFP_HIGH users get access to the first
lower watermark and can be called the "high priority reserve".

Over time, callers had a requirement to not block when fallback options
were available.  Some have abused __GFP_WAIT leading to a situation where
an optimisitic allocation with a fallback option can access atomic
reserves.

This patch uses __GFP_ATOMIC to identify callers that are truely atomic,
cannot sleep and have no alternative.  High priority users continue to use
__GFP_HIGH.  __GFP_DIRECT_RECLAIM identifies callers that can sleep and
are willing to enter direct reclaim.  __GFP_KSWAPD_RECLAIM to identify
callers that want to wake kswapd for background reclaim.  __GFP_WAIT is
redefined as a caller that is willing to enter direct reclaim and wake
kswapd for background reclaim.

This patch then converts a number of sites

o __GFP_ATOMIC is used by callers that are high priority and have memory
  pools for those requests. GFP_ATOMIC uses this flag.

o Callers that have a limited mempool to guarantee forward progress clear
  __GFP_DIRECT_RECLAIM but keep __GFP_KSWAPD_RECLAIM. bio allocations fall
  into this category where kswapd will still be woken but atomic reserves
  are not used as there is a one-entry mempool to guarantee progress.

o Callers that are checking if they are non-blocking should use the
  helper gfpflags_allow_blocking() where possible. This is because
  checking for __GFP_WAIT as was done historically now can trigger false
  positives. Some exceptions like dm-crypt.c exist where the code intent
  is clearer if __GFP_DIRECT_RECLAIM is used instead of the helper due to
  flag manipulations.

o Callers that built their own GFP flags instead of starting with GFP_KERNEL
  and friends now also need to specify __GFP_KSWAPD_RECLAIM.

The first key hazard to watch out for is callers that removed __GFP_WAIT
and was depending on access to atomic reserves for inconspicuous reasons.
In some cases it may be appropriate for them to use __GFP_HIGH.

The second key hazard is callers that assembled their own combination of
GFP flags instead of starting with something like GFP_KERNEL.  They may
now wish to specify __GFP_KSWAPD_RECLAIM.  It's almost certainly harmless
if it's missed in most cases as other activity will wake kswapd.
Signed-off-by: NMel Gorman <mgorman@techsingularity.net>
Acked-by: NVlastimil Babka <vbabka@suse.cz>
Acked-by: NMichal Hocko <mhocko@suse.com>
Acked-by: NJohannes Weiner <hannes@cmpxchg.org>
Cc: Christoph Lameter <cl@linux.com>
Cc: David Rientjes <rientjes@google.com>
Cc: Vitaly Wool <vitalywool@gmail.com>
Cc: Rik van Riel <riel@redhat.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

Instead of having users check for FL_POSIX or FL_FLOCK to call the correct
locks API function, use the check within locks_lock_inode_wait().  This
allows for some later cleanup.
Signed-off-by: NBenjamin Coddington <bcodding@redhat.com>
Signed-off-by: NJeff Layton <jeff.layton@primarydata.com>

The NFSv4 delegation spec allows the server to tell a client to limit how
much data it cache after the file is closed. In return, the server
guarantees enough free space to avoid ENOSPC situations, etc.
Prior to this patch, we assumed we could always cache aggressively after
close. Unfortunately, this causes problems with servers that set the
limit to 0 and therefore do not offer any ENOSPC guarantees.
Signed-off-by: NTrond Myklebust <trond.myklebust@primarydata.com>

generic_file_write_iter() will already do an fsync on our behalf
if the file descriptor is O_SYNC or the file is marked as IS_SYNC.
Signed-off-by: NTrond Myklebust <trond.myklebust@primarydata.com>

And call nfs_file_clear_open_context() directly.  This makes it obvious
that nfs_file_release() will always return 0.
Signed-off-by: NAnna Schumaker <Anna.Schumaker@Netapp.com>
Signed-off-by: NTrond Myklebust <trond.myklebust@primarydata.com>

Jerome reported seeing a warning pop when working with a swapfile on
NFS. The nfs_swap_activate can end up calling sk_set_memalloc while
holding the rcu_read_lock and that function can sleep.

To fix that, we need to take a reference to the xprt while holding the
rcu_read_lock, set the socket up for swapping and then drop that
reference. But, xprt_put is not exported and having NFS deal with the
underlying xprt is a bit of layering violation anyway.

Fix this by adding a set of activate/deactivate functions that take a
rpc_clnt pointer instead of an rpc_xprt, and have nfs_swap_activate and
nfs_swap_deactivate call those.

Also, add a per-rpc_clnt atomic counter to keep track of the number of
active swapfiles associated with it. When the counter does a 0->1
transition, we enable swapping on the xprt, when we do a 1->0 transition
we disable swapping on it.

This also allows us to be a bit more selective with the RPC_TASK_SWAPPER
flag. If non-swapper and swapper clnts are sharing a xprt, then we only
need to flag the tasks from the swapper clnt with that flag.
Acked-by: NMel Gorman <mgorman@suse.de>
Reported-by: NJerome Marchand <jmarchan@redhat.com>
Signed-off-by: NJeff Layton <jeff.layton@primarydata.com>
Reviewed-by: NChuck Lever <chuck.lever@oracle.com>
Signed-off-by: NTrond Myklebust <trond.myklebust@primarydata.com>

Signed-off-by: NAl Viro <viro@zeniv.linux.org.uk>

... avoiding write_iter/fcntl races.
Signed-off-by: NAl Viro <viro@zeniv.linux.org.uk>

All places outside of core VFS that checked ->read and ->write for being NULL or
called the methods directly are gone now, so NULL {read,write} with non-NULL
{read,write}_iter will do the right thing in all cases.
Signed-off-by: NAl Viro <viro@zeniv.linux.org.uk>

If the caller does not specify the O_SYNC flag, then it is legitimate
to return from O_DIRECT without doing a pNFS layoutcommit operation.
However if the file is opened O_DIRECT|O_SYNC then we'd better get it
right.
Signed-off-by: NTrond Myklebust <trond.myklebust@primarydata.com>

File unlock needs to update both data and metadata on the NFS server
in order to act as a synchronisation point for other clients.
Signed-off-by: NTrond Myklebust <trond.myklebust@primarydata.com>

struct kiocb now is a generic I/O container, so move it to fs.h.
Also do a #include diet for aio.h while we're at it.
Signed-off-by: NChristoph Hellwig <hch@lst.de>
Signed-off-by: NAl Viro <viro@zeniv.linux.org.uk>

nfs_vm_page_mkwrite() should wait until the page cache invalidation
is finished. This is the second patch in a 2 patch series to deprecate
the NFS client's reliance on nfs_release_page() in the context of
nfs_invalidate_mapping().
Signed-off-by: NTrond Myklebust <trond.myklebust@primarydata.com>

When invalidating the page cache for a regular file, we want to first
sync all dirty data to disk and then call invalidate_inode_pages2().
The latter relies on nfs_launder_page() and nfs_release_page() to deal
respectively with dirty pages, and unstable written pages.

When commit 95905446 ("NFS: avoid deadlocks with loop-back mounted
NFS filesystems.") changed the behaviour of nfs_release_page(), then it
made it possible for invalidate_inode_pages2() to fail with an EBUSY.
Unfortunately, that error is then propagated back to read().

Let's therefore work around the problem for now by protecting the call
to sync the data and invalidate_inode_pages2() so that they are atomic
w.r.t. the addition of new writes.
Later on, we can revisit whether or not we still need nfs_launder_page()
and nfs_release_page().
Signed-off-by: NTrond Myklebust <trond.myklebust@primarydata.com>

The O_DIRECT code will grab the inode->i_mutex and flush out buffered
writes, before scheduling a read or a write. However there is no
equivalent in the buffered write code to wait for O_DIRECT to complete.

Fixes a reported issue in xfstests generic/133, when first performing an
O_DIRECT write followed by a buffered write.
Signed-off-by: NTrond Myklebust <trond.myklebust@primarydata.com>
Tested-by: NChuck Lever <chuck.lever@oracle.com>

Nobody uses it anymore.

[akpm@linux-foundation.org: fix filemap_xip.c]
Signed-off-by: NKirill A. Shutemov <kirill.shutemov@linux.intel.com>
Cc: Wu Fengguang <fengguang.wu@intel.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

REQ_KERNEL is no longer used. Remove it and drop the redundant uio
argument to nfs_file_direct_{read,write}.
Signed-off-by: NMartin K. Petersen <martin.petersen@oracle.com>
Cc: Christoph Hellwig <hch@infradead.org>
Reported-by: NDan Carpenter <dan.carpenter@oracle.com>
Signed-off-by: NJens Axboe <axboe@fb.com>

Now that nfs_release_page() doesn't block indefinitely, other deadlock
avoidance mechanisms aren't needed.
 - it doesn't hurt for kswapd to block occasionally.  If it doesn't
   want to block it would clear __GFP_WAIT.  The current_is_kswapd()
   was only added to avoid deadlocks and we have a new approach for
   that.
 - memory allocation in the SUNRPC layer can very rarely try to
   ->releasepage() a page it is trying to handle.  The deadlock
   is removed as nfs_release_page() doesn't block indefinitely.

So we don't need to set PF_FSTRANS for sunrpc network operations any
more.
Signed-off-by: NNeilBrown <neilb@suse.de>
Acked-by: NJeff Layton <jlayton@primarydata.com>
Signed-off-by: NTrond Myklebust <trond.myklebust@primarydata.com>

If nfs_release_page() is called on a sequence of pages which are all
in the same file which is blocked on COMMIT, each page could
contribute a 1 second delay which could be come excessive.  I have
seen delays of as much as 208 seconds.

To keep the delay to one second, mark the bdi as write-congested
if the commit didn't finished.  Once it does finish, the
write-congested flag will be cleared by nfs_commit_release_pages().

With this, the longest total delay in try_to_free_pages that I have
seen is under 3 seconds.  With no waiting in nfs_release_page at all
I have seen delays of nearly 1.5 seconds.
Signed-off-by: NNeilBrown <neilb@suse.de>
Acked-by: NJeff Layton <jlayton@primarydata.com>
Signed-off-by: NTrond Myklebust <trond.myklebust@primarydata.com>

Support for loop-back mounted NFS filesystems is useful when NFS is
used to access shared storage in a high-availability cluster.

If the node running the NFS server fails, some other node can mount the
filesystem and start providing NFS service.  If that node already had
the filesystem NFS mounted, it will now have it loop-back mounted.

nfsd can suffer a deadlock when allocating memory and entering direct
reclaim.
While direct reclaim does not write to the NFS filesystem it can send
and wait for a COMMIT through nfs_release_page().

This patch modifies nfs_release_page() to wait a limited time for the
commit to complete - one second.  If the commit doesn't complete
in this time, nfs_release_page() will fail.  This means it might now
fail in some cases where it wouldn't before.  These cases are only
when 'gfp' includes '__GFP_WAIT'.

nfs_release_page() is only called by try_to_release_page(), and that
can only be called on an NFS page with required 'gfp' flags from
 - page_cache_pipe_buf_steal() in splice.c
 - shrink_page_list() in vmscan.c
 - invalidate_inode_pages2_range() in truncate.c

The first two handle failure quite safely.  The last is only called
after ->launder_page() has been called, and that will have waited
for the commit to finish already.

So aborting if the commit takes longer than 1 second is perfectly safe.
Signed-off-by: NNeilBrown <neilb@suse.de>
Acked-by: NJeff Layton <jlayton@primarydata.com>
Signed-off-by: NTrond Myklebust <trond.myklebust@primarydata.com>

sparse says:

fs/nfs/file.c:543:60: warning: incorrect type in argument 1 (different address spaces)
fs/nfs/file.c:543:60:    expected struct rpc_xprt *xprt
fs/nfs/file.c:543:60:    got struct rpc_xprt [noderef] <asn:4>*cl_xprt
fs/nfs/file.c:548:53: warning: incorrect type in argument 1 (different address spaces)
fs/nfs/file.c:548:53:    expected struct rpc_xprt *xprt
fs/nfs/file.c:548:53:    got struct rpc_xprt [noderef] <asn:4>*cl_xprt

cl_xprt is RCU-managed, so we need to take care to dereference and use
it while holding the RCU read lock.

Cc: Mel Gorman <mgorman@suse.de>
Signed-off-by: NJeff Layton <jlayton@primarydata.com>
Signed-off-by: NTrond 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: NChristoph Hellwig <hch@lst.de>
Signed-off-by: NTrond Myklebust <trond.myklebust@primarydata.com>

GFS2 and NFS have setlease routines that always just return -EINVAL.
Turn that into a generic routine that can live in fs/libfs.c.

Cc: <linux-nfs@vger.kernel.org>
Cc: Steven Whitehouse <swhiteho@redhat.com>
Cc: <cluster-devel@redhat.com>
Signed-off-by: NJeff Layton <jlayton@primarydata.com>
Acked-by: NTrond Myklebust <trond.myklebust@primarydata.com>
Reviewed-by: NChristoph Hellwig <hch@lst.de>

The current "wait_on_bit" interface requires an 'action'
function to be provided which does the actual waiting.
There are over 20 such functions, many of them identical.
Most cases can be satisfied by one of just two functions, one
which uses io_schedule() and one which just uses schedule().

So:
 Rename wait_on_bit and        wait_on_bit_lock to
        wait_on_bit_action and wait_on_bit_lock_action
 to make it explicit that they need an action function.

 Introduce new wait_on_bit{,_lock} and wait_on_bit{,_lock}_io
 which are *not* given an action function but implicitly use
 a standard one.
 The decision to error-out if a signal is pending is now made
 based on the 'mode' argument rather than being encoded in the action
 function.

 All instances of the old wait_on_bit and wait_on_bit_lock which
 can use the new version have been changed accordingly and their
 action functions have been discarded.
 wait_on_bit{_lock} does not return any specific error code in the
 event of a signal so the caller must check for non-zero and
 interpolate their own error code as appropriate.

The wait_on_bit() call in __fscache_wait_on_invalidate() was
ambiguous as it specified TASK_UNINTERRUPTIBLE but used
fscache_wait_bit_interruptible as an action function.
David Howells confirms this should be uniformly
"uninterruptible"

The main remaining user of wait_on_bit{,_lock}_action is NFS
which needs to use a freezer-aware schedule() call.

A comment in fs/gfs2/glock.c notes that having multiple 'action'
functions is useful as they display differently in the 'wchan'
field of 'ps'. (and /proc/$PID/wchan).
As the new bit_wait{,_io} functions are tagged "__sched", they
will not show up at all, but something higher in the stack.  So
the distinction will still be visible, only with different
function names (gds2_glock_wait versus gfs2_glock_dq_wait in the
gfs2/glock.c case).

Since first version of this patch (against 3.15) two new action
functions appeared, on in NFS and one in CIFS.  CIFS also now
uses an action function that makes the same freezer aware
schedule call as NFS.
Signed-off-by: NNeilBrown <neilb@suse.de>
Acked-by: David Howells <dhowells@redhat.com> (fscache, keys)
Acked-by: Steven Whitehouse <swhiteho@redhat.com> (gfs2)
Acked-by: NPeter Zijlstra <peterz@infradead.org>
Cc: Oleg Nesterov <oleg@redhat.com>
Cc: Steve French <sfrench@samba.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Link: http://lkml.kernel.org/r/20140707051603.28027.72349.stgit@notabene.brownSigned-off-by: NIngo Molnar <mingo@kernel.org>

Signed-off-by: NAl Viro <viro@zeniv.linux.org.uk>

Currently, the fl_owner isn't set for flock locks. Some filesystems use
byte-range locks to simulate flock locks and there is a common idiom in
those that does:

    fl->fl_owner = (fl_owner_t)filp;
    fl->fl_start = 0;
    fl->fl_end = OFFSET_MAX;

Since flock locks are generally "owned" by the open file description,
move this into the common flock lock setup code. The fl_start and fl_end
fields are already set appropriately, so remove the unneeded setting of
that in flock ops in those filesystems as well.

Finally, the lease code also sets the fl_owner as if they were owned by
the process and not the open file description. This is incorrect as
leases have the same ownership semantics as flock locks. Set them the
same way. The lease code doesn't actually use the fl_owner value for
anything, so this is more for consistency's sake than a bugfix.
Reported-by: NTrond Myklebust <trond.myklebust@primarydata.com>
Signed-off-by: NJeff Layton <jlayton@poochiereds.net>
Acked-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> (Staging portion)
Acked-by: NJ. Bruce Fields <bfields@fieldses.org>