When gfs2 was converted to use fs_context, the initialisation of the
mount args structure to the currently active args was lost with the
removal of gfs2_remount_fs(), so the checks of the new args on remount
became checks against the default values instead of the current ones.
This caused unexpected remount behaviour and test failures (xfstests
generic/294, generic/306 and generic/452).

Reinstate the args initialisation, this time in gfs2_init_fs_context()
and conditional upon fc->purpose, as that's the only time we get control
before the mount args are parsed in the remount process.

Fixes: 1f52aa08d12f ("gfs2: Convert gfs2 to fs_context")
Signed-off-by: Andrew Price <anprice@redhat.com>
Signed-off-by: Andreas Gruenbacher <agruenba@redhat.com>

gfs2 and gfs2meta share an ->init_fs_context function which allocates an
args structure stored in fc->fs_private. gfs2 registers a ->free
function to free this memory when the fs_context is cleaned up, but
there was not one registered for gfs2meta, causing a leak.

Register a ->free function for gfs2meta. The existing gfs2_fc_free
function does what we need.

Reported-by: syzbot+c2fdfd2b783754878fb6@syzkaller.appspotmail.com
Fixes: 1f52aa08d12f ("gfs2: Convert gfs2 to fs_context")
Signed-off-by: Andrew Price <anprice@redhat.com>
Signed-off-by: Bob Peterson <rpeterso@redhat.com>
Signed-off-by: Andreas Gruenbacher <agruenba@redhat.com>

Pull more mount API conversions from Al Viro:
 "Assorted conversions of options parsing to new API.

  gfs2 is probably the most serious one here; the rest is trivial stuff.

  Other things in what used to be #work.mount are going to wait for the
  next cycle (and preferably go via git trees of the filesystems
  involved)"

* 'work.mount3' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs:
  gfs2: Convert gfs2 to fs_context
  vfs: Convert spufs to use the new mount API
  vfs: Convert hypfs to use the new mount API
  hypfs: Fix error number left in struct pointer member
  vfs: Convert functionfs to use the new mount API
  vfs: Convert bpf to use the new mount API

Convert gfs2 and gfs2meta to fs_context. Removes the duplicated vfs code
from gfs2_mount and instead uses the new vfs_get_block_super() before
switching the ->root to the appropriate dentry.

The mount option parsing has been converted to the new API and error
reporting for invalid options has been made more precise at the same
time.

All of the mount/remount code has been moved into ops_fstype.c

Signed-off-by: Andrew Price <anprice@redhat.com>
Signed-off-by: David Howells <dhowells@redhat.com>
cc: cluster-devel@redhat.com
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>

In function sweep_bh_for_rgrps, which is a helper for punch_hole,
it uses variable buf_in_tr to keep track of when it needs to commit
pending block frees on a partial delete that overflows the
transaction created for the delete. The problem is that the
variable was initialized at the start of function sweep_bh_for_rgrps
but it was never cleared, even when starting a new transaction.

This patch reinitializes the variable when the transaction is
ended, so the next transaction starts out with it cleared.

Fixes: d552a2b9b33e ("GFS2: Non-recursive delete")
Cc: stable@vger.kernel.org # v4.12+
Signed-off-by: Bob Peterson <rpeterso@redhat.com>
Signed-off-by: Andreas Gruenbacher <agruenba@redhat.com>

On filesystems with a block size smaller than PAGE_SIZE, page_mkwrite is
called for each memory-mapped page before that page can be written to.
When such a memory-mapped file is truncated down to size x which is not
a multiple of the page size and then back to a larger size, the page
straddling size x can end up with a partial block mapping.  In that
case, make sure to mark that page read-only so that page_mkwrite will be
called before the page can be written to the next time.

(There is no point in marking the page straddling size x read-only when
truncating down as writing to memory beyond the end of the file will
result in SIGBUS instead of growing the file.)

Fixes xfstests generic/029, generic/030 on filesystems with a block size
smaller than PAGE_SIZE.

Signed-off-by: Andreas Gruenbacher <agruenba@redhat.com>

Because s_vfs_rename_mutex is not cluster-wide, multiple nodes can
reverse the roles of which directories are "old" and which are "new" for
the purposes of rename. This can cause deadlocks where two nodes end up
waiting for each other.

There can be several layers of directory dependencies across many nodes.

This patch fixes the problem by acquiring all gfs2_rename's inode glocks
asychronously and waiting for all glocks to be acquired.  That way all
inodes are locked regardless of the order.

The timeout value for multiple asynchronous glocks is calculated to be
the total of the individual wait times for each glock times two.

Since gfs2_exchange is very similar to gfs2_rename, both functions are
patched in the same way.

A new async glock wait queue, sd_async_glock_wait, keeps a list of
waiters for these events. If gfs2's holder_wake function detects an
async holder, it wakes up any waiters for the event. The waiter only
tests whether any of its requests are still pending.

Since the glocks are sent to dlm asychronously, the wait function needs
to check to see which glocks, if any, were granted.

If a glock is granted by dlm (and therefore held), its minimum hold time
is checked and adjusted as necessary, as other glock grants do.

If the event times out, all glocks held thus far must be dequeued to
resolve any existing deadlocks.  Then, if there are any outstanding
locking requests, we need to loop around and wait for dlm to respond to
those requests too.  After we release all requests, we return -ESTALE to
the caller (vfs rename) which loops around and retries the request.

    Node1           Node2
    ---------       ---------
1.  Enqueue A       Enqueue B
2.  Enqueue B       Enqueue A
3.  A granted
6.                  B granted
7.  Wait for B
8.                  Wait for A
9.                  A times out (since Node 1 holds A)
10.                 Dequeue B (since it was granted)
11.                 Wait for all requests from DLM
12. B Granted (since Node2 released it in step 10)
13. Rename
14. Dequeue A
15.                 DLM Grants A
16.                 Dequeue A (due to the timeout and since we
                    no longer have B held for our task).
17. Dequeue B
18.                 Return -ESTALE to vfs
19.                 VFS retries the operation, goto step 1.

This release-all-locks / acquire-all-locks may slow rename / exchange
down as both nodes struggle in the same way and do the same thing.
However, this will only happen when there is contention for the same
inodes, which ought to be rare.

Signed-off-by: Bob Peterson <rpeterso@redhat.com>
Signed-off-by: Andreas Gruenbacher <agruenba@redhat.com>

This patch moves the code that updates glock minimum hold
time to a separate function. This will be called by a future
patch.

Signed-off-by: Andreas Gruenbacher <agruenba@redhat.com>
Signed-off-by: Bob Peterson <rpeterso@redhat.com>

Before this patch, gfs2_rename added a holder for the rgrp glock to
its array of holders, ghs. There's nothing wrong with that, but this
patch separates it into a separate holder. This is done to ensure
it's always locked last as per the proper glock lock ordering,
and also to pave the way for a future patch in which we will
lock the non-rgrp glocks asynchronously.

Signed-off-by: Bob Peterson <rpeterso@redhat.com>
Signed-off-by: Andreas Gruenbacher <agruenba@redhat.com>

The brelse() function tests whether its argument is NULL and then
returns immediately.  Thus the test around the call is not needed.

This issue was detected by using the Coccinelle software.

[The same applies to brelse() in gfs2_dir_no_add (which Coccinelle
apparently missed), so fix that as well.]

Signed-off-by: Markus Elfring <elfring@users.sourceforge.net>
Signed-off-by: Andreas Gruenbacher <agruenba@redhat.com>