Two of the USB Gadgets were poking around in the internals of struct ida
in order to determine if it is empty.  Add the appropriate abstraction.

Link: http://lkml.kernel.org/r/1480369871-5271-63-git-send-email-mawilcox@linuxonhyperv.comSigned-off-by: NMatthew Wilcox <willy@linux.intel.com>
Acked-by: NKonstantin Khlebnikov <koct9i@gmail.com>
Tested-by: NKirill A. Shutemov <kirill.shutemov@linux.intel.com>
Cc: Ross Zwisler <ross.zwisler@linux.intel.com>
Cc: Felipe Balbi <balbi@kernel.org>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: Michal Nazarewicz <mina86@mina86.com>
Cc: Matthew Wilcox <mawilcox@microsoft.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

The random iteration test only inserts order-0 entries currently.
Update it to insert entries of order between 7 and 0.  Also make the
maximum index configurable, make some variables static, make the test
duration variable, remove some useless spinning, and add a fifth thread
which calls tag_tagged_items().

Link: http://lkml.kernel.org/r/1480369871-5271-62-git-send-email-mawilcox@linuxonhyperv.comSigned-off-by: NMatthew Wilcox <mawilcox@microsoft.com>
Tested-by: NKirill A. Shutemov <kirill.shutemov@linux.intel.com>
Cc: Konstantin Khlebnikov <koct9i@gmail.com>
Cc: Ross Zwisler <ross.zwisler@linux.intel.com>
Cc: Matthew Wilcox <mawilcox@microsoft.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

When replacing an entry with NULL, we need to delete any sibling
entries.  Also account deleting exceptional entries properly.  Also fix
a bug with radix_tree_iter_replace() where we would fail to remove
entirely freed nodes.  Also fix accounting bug when switching between
normal and exceptional entries with replace_slot.  Also add testcases
for all these bugs.

Link: http://lkml.kernel.org/r/1480369871-5271-61-git-send-email-mawilcox@linuxonhyperv.comSigned-off-by: NMatthew Wilcox <mawilcox@microsoft.com>
Tested-by: NKirill A. Shutemov <kirill.shutemov@linux.intel.com>
Cc: Konstantin Khlebnikov <koct9i@gmail.com>
Cc: Ross Zwisler <ross.zwisler@linux.intel.com>
Cc: Matthew Wilcox <mawilcox@microsoft.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

Calculate how many nodes we need to allocate to split an old_order entry
into multiple entries, each of size new_order.  The test suite checks
that we allocated exactly the right number of nodes; neither too many
(checked by rtp->nr == 0), nor too few (checked by comparing
nr_allocated before and after the call to radix_tree_split()).

Link: http://lkml.kernel.org/r/1480369871-5271-60-git-send-email-mawilcox@linuxonhyperv.comSigned-off-by: NMatthew Wilcox <willy@linux.intel.com>
Tested-by: NKirill A. Shutemov <kirill.shutemov@linux.intel.com>
Cc: Konstantin Khlebnikov <koct9i@gmail.com>
Cc: Ross Zwisler <ross.zwisler@linux.intel.com>
Cc: Matthew Wilcox <mawilcox@microsoft.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

This new function splits a larger multiorder entry into smaller entries
(potentially multi-order entries).  These entries are initialised to
RADIX_TREE_RETRY to ensure that RCU walkers who see this state aren't
confused.  The caller should then call radix_tree_for_each_slot() and
radix_tree_replace_slot() in order to turn these retry entries into the
intended new entries.  Tags are replicated from the original multiorder
entry into each new entry.

Link: http://lkml.kernel.org/r/1480369871-5271-59-git-send-email-mawilcox@linuxonhyperv.comSigned-off-by: NMatthew Wilcox <willy@linux.intel.com>
Tested-by: NKirill A. Shutemov <kirill.shutemov@linux.intel.com>
Cc: Konstantin Khlebnikov <koct9i@gmail.com>
Cc: Ross Zwisler <ross.zwisler@linux.intel.com>
Cc: Matthew Wilcox <mawilcox@microsoft.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

This new function allows for the replacement of many smaller entries in
the radix tree with one larger multiorder entry.  From the point of view
of an RCU walker, they may see a mixture of the smaller entries and the
large entry during the same walk, but they will never see NULL for an
index which was populated before the join.

Link: http://lkml.kernel.org/r/1480369871-5271-58-git-send-email-mawilcox@linuxonhyperv.comSigned-off-by: NMatthew Wilcox <willy@linux.intel.com>
Tested-by: NKirill A. Shutemov <kirill.shutemov@linux.intel.com>
Cc: Konstantin Khlebnikov <koct9i@gmail.com>
Cc: Ross Zwisler <ross.zwisler@linux.intel.com>
Cc: Matthew Wilcox <mawilcox@microsoft.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

This is an exceptionally complicated function with just one caller
(tag_pages_for_writeback).  We devote a large portion of the runtime of
the test suite to testing this one function which has one caller.  By
introducing the new function radix_tree_iter_tag_set(), we can eliminate
all of the complexity while keeping the performance.  The caller can now
use a fairly standard radix_tree_for_each() loop, and it doesn't need to
worry about tricksy things like 'start' wrapping.

The test suite continues to spend a large amount of time investigating
this function, but now it's testing the underlying primitives such as
radix_tree_iter_resume() and the radix_tree_for_each_tagged() iterator
which are also used by other parts of the kernel.

Link: http://lkml.kernel.org/r/1480369871-5271-57-git-send-email-mawilcox@linuxonhyperv.comSigned-off-by: NMatthew Wilcox <willy@infradead.org>
Tested-by: NKirill A. Shutemov <kirill.shutemov@linux.intel.com>
Cc: Konstantin Khlebnikov <koct9i@gmail.com>
Cc: Ross Zwisler <ross.zwisler@linux.intel.com>
Cc: Matthew Wilcox <mawilcox@microsoft.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

This rather complicated function can be better implemented as an
iterator.  It has only one caller, so move the functionality to the only
place that needs it.  Update the test suite to follow the same pattern.

Link: http://lkml.kernel.org/r/1480369871-5271-56-git-send-email-mawilcox@linuxonhyperv.comSigned-off-by: NMatthew Wilcox <mawilcox@microsoft.com>
Acked-by: NKonstantin Khlebnikov <koct9i@gmail.com>
Tested-by: NKirill A. Shutemov <kirill.shutemov@linux.intel.com>
Cc: Ross Zwisler <ross.zwisler@linux.intel.com>
Cc: Matthew Wilcox <mawilcox@microsoft.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

This fixes several interlinked problems with the iterators in the
presence of multiorder entries.

1. radix_tree_iter_next() would only advance by one slot, which would
   result in the iterators returning the same entry more than once if
   there were sibling entries.

2. radix_tree_next_slot() could return an internal pointer instead of
   a user pointer if a tagged multiorder entry was immediately followed by
   an entry of lower order.

3. radix_tree_next_slot() expanded to a lot more code than it used to
   when multiorder support was compiled in.  And I wasn't comfortable with
   entry_to_node() being in a header file.

Fixing radix_tree_iter_next() for the presence of sibling entries
necessarily involves examining the contents of the radix tree, so we now
need to pass 'slot' to radix_tree_iter_next(), and we need to change the
calling convention so it is called *before* dropping the lock which
protects the tree.  Also rename it to radix_tree_iter_resume(), as some
people thought it was necessary to call radix_tree_iter_next() each time
around the loop.

radix_tree_next_slot() becomes closer to how it looked before multiorder
support was introduced.  It only checks to see if the next entry in the
chunk is a sibling entry or a pointer to a node; this should be rare
enough that handling this case out of line is not a performance impact
(and such impact is amortised by the fact that the entry we just
processed was a multiorder entry).  Also, radix_tree_next_slot() used to
force a new chunk lookup for untagged entries, which is more expensive
than the out of line sibling entry skipping.

Link: http://lkml.kernel.org/r/1480369871-5271-55-git-send-email-mawilcox@linuxonhyperv.comSigned-off-by: NMatthew Wilcox <mawilcox@microsoft.com>
Tested-by: NKirill A. Shutemov <kirill.shutemov@linux.intel.com>
Cc: Konstantin Khlebnikov <koct9i@gmail.com>
Cc: Ross Zwisler <ross.zwisler@linux.intel.com>
Cc: Matthew Wilcox <mawilcox@microsoft.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

We drop the lock which protects the radix tree, so we must call
radix_tree_iter_next() in order to avoid a modification to the tree
invalidating the iterator state.

Link: http://lkml.kernel.org/r/1480369871-5271-54-git-send-email-mawilcox@linuxonhyperv.comSigned-off-by: NMatthew Wilcox <mawilcox@microsoft.com>
Tested-by: NKirill A. Shutemov <kirill.shutemov@linux.intel.com>
Cc: Konstantin Khlebnikov <koct9i@gmail.com>
Cc: Ross Zwisler <ross.zwisler@linux.intel.com>
Cc: Matthew Wilcox <mawilcox@microsoft.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

Print the indices of the entries as unsigned (instead of signed)
integers and print the parent node of each entry to help navigate around
larger trees where the layout is not quite so obvious.  Print the
indices covered by a node.  Rearrange the order of fields printed so the
indices and parents line up for each type of entry.

Link: http://lkml.kernel.org/r/1480369871-5271-53-git-send-email-mawilcox@linuxonhyperv.comSigned-off-by: NMatthew Wilcox <willy@infradead.org>
Tested-by: NKirill A. Shutemov <kirill.shutemov@linux.intel.com>
Cc: Konstantin Khlebnikov <koct9i@gmail.com>
Cc: Ross Zwisler <ross.zwisler@linux.intel.com>
Cc: Matthew Wilcox <mawilcox@microsoft.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

Since this function is specialised to the radix tree, pass in the node
and tag to calculate the address of the bitmap in
radix_tree_find_next_bit() instead of the caller.  Likewise, there is no
need to pass in the size of the bitmap.

Link: http://lkml.kernel.org/r/1480369871-5271-52-git-send-email-mawilcox@linuxonhyperv.comSigned-off-by: NMatthew Wilcox <willy@infradead.org>
Tested-by: NKirill A. Shutemov <kirill.shutemov@linux.intel.com>
Cc: Konstantin Khlebnikov <koct9i@gmail.com>
Cc: Ross Zwisler <ross.zwisler@linux.intel.com>
Cc: Matthew Wilcox <mawilcox@microsoft.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

Similar to node_tag_clear(), factor node_tag_set() out of
radix_tree_range_tag_if_tagged().

Link: http://lkml.kernel.org/r/1480369871-5271-51-git-send-email-mawilcox@linuxonhyperv.comSigned-off-by: NMatthew Wilcox <willy@linux.intel.com>
Tested-by: NKirill A. Shutemov <kirill.shutemov@linux.intel.com>
Cc: Konstantin Khlebnikov <koct9i@gmail.com>
Cc: Ross Zwisler <ross.zwisler@linux.intel.com>
Cc: Matthew Wilcox <mawilcox@microsoft.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

I want to be able to reference node->parent after freeing node.

Currently node->parent is in a union with rcu_head, so it is overwritten
when the node is put on the RCU list.  We know that private_list is not
referenced after the node is freed, so it is safe for these two members
to share space.

Link: http://lkml.kernel.org/r/1480369871-5271-50-git-send-email-mawilcox@linuxonhyperv.comSigned-off-by: NMatthew Wilcox <willy@infradead.org>
Tested-by: NKirill A. Shutemov <kirill.shutemov@linux.intel.com>
Cc: Konstantin Khlebnikov <koct9i@gmail.com>
Cc: Ross Zwisler <ross.zwisler@linux.intel.com>
Cc: Matthew Wilcox <mawilcox@microsoft.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

Signed-off-by: NMatthew Wilcox <willy@linux.intel.com>
Tested-by: NKirill A. Shutemov <kirill.shutemov@linux.intel.com>
Cc: Konstantin Khlebnikov <koct9i@gmail.com>
Cc: Ross Zwisler <ross.zwisler@linux.intel.com>
Cc: Matthew Wilcox <mawilcox@microsoft.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

Remove the old find_next_bit code in favour of linking in the find_bit
code from tools/lib.

Link: http://lkml.kernel.org/r/1480369871-5271-48-git-send-email-mawilcox@linuxonhyperv.comSigned-off-by: NMatthew Wilcox <willy@linux.intel.com>
Tested-by: NKirill A. Shutemov <kirill.shutemov@linux.intel.com>
Cc: Konstantin Khlebnikov <koct9i@gmail.com>
Cc: Ross Zwisler <ross.zwisler@linux.intel.com>
Cc: Matthew Wilcox <mawilcox@microsoft.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

I need the following functions for the radix tree:

  bitmap_fill
  bitmap_empty
  bitmap_full

Copy the implementations from include/linux/bitmap.h
Signed-off-by: NMatthew Wilcox <willy@linux.intel.com>
Tested-by: NKirill A. Shutemov <kirill.shutemov@linux.intel.com>
Cc: Konstantin Khlebnikov <koct9i@gmail.com>
Cc: Ross Zwisler <ross.zwisler@linux.intel.com>
Cc: Matthew Wilcox <mawilcox@microsoft.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

This probably doubles the size of each item allocated by the test suite
but it lets us check a few more things, and may be needed for upcoming
API changes that require the caller pass in the order of the entry.

Link: http://lkml.kernel.org/r/1480369871-5271-46-git-send-email-mawilcox@linuxonhyperv.comSigned-off-by: NMatthew Wilcox <mawilcox@microsoft.com>
Tested-by: NKirill A. Shutemov <kirill.shutemov@linux.intel.com>
Cc: Konstantin Khlebnikov <koct9i@gmail.com>
Cc: Ross Zwisler <ross.zwisler@linux.intel.com>
Cc: Matthew Wilcox <mawilcox@microsoft.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

item_kill_tree() assumes that everything in the tree is a pointer to a
struct item, which is annoying when testing the behaviour of exceptional
entries.  Fix it to delete exceptional entries on the assumption they
don't need to be freed.

Link: http://lkml.kernel.org/r/1480369871-5271-45-git-send-email-mawilcox@linuxonhyperv.comSigned-off-by: NMatthew Wilcox <mawilcox@microsoft.com>
Tested-by: NKirill A. Shutemov <kirill.shutemov@linux.intel.com>
Cc: Konstantin Khlebnikov <koct9i@gmail.com>
Cc: Ross Zwisler <ross.zwisler@linux.intel.com>
Cc: Matthew Wilcox <mawilcox@microsoft.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

Calling rcu_barrier() allows all of the rcu-freed memory to be actually
returned to the pool, and allows nr_allocated to return to 0.  As well
as allowing diffs between runs to be more useful, it also lets us
pinpoint leaks more effectively.

Link: http://lkml.kernel.org/r/1480369871-5271-44-git-send-email-mawilcox@linuxonhyperv.comSigned-off-by: NMatthew Wilcox <mawilcox@microsoft.com>
Tested-by: NKirill A. Shutemov <kirill.shutemov@linux.intel.com>
Cc: Konstantin Khlebnikov <koct9i@gmail.com>
Cc: Ross Zwisler <ross.zwisler@linux.intel.com>
Cc: Matthew Wilcox <mawilcox@microsoft.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

This adds simple benchmark for iterator similar to one I've used for
commit 78c1d784 ("radix-tree: introduce bit-optimized iterator")

Building with make BENCHMARK=1 set radix tree order to 6, this allows to
get performance comparable to in kernel performance.

Link: http://lkml.kernel.org/r/1480369871-5271-43-git-send-email-mawilcox@linuxonhyperv.comSigned-off-by: NKonstantin Khlebnikov <koct9i@gmail.com>
Signed-off-by: NMatthew Wilcox <mawilcox@microsoft.com>
Tested-by: NKirill A. Shutemov <kirill.shutemov@linux.intel.com>
Cc: Ross Zwisler <ross.zwisler@linux.intel.com>
Cc: Matthew Wilcox <mawilcox@microsoft.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

Each thread needs to register itself with RCU, otherwise the reading
thread's read lock has no effect and the freeing thread will free the
memory in the tree without waiting for the read lock to be dropped.

Link: http://lkml.kernel.org/r/1480369871-5271-42-git-send-email-mawilcox@linuxonhyperv.comSigned-off-by: NMatthew Wilcox <mawilcox@microsoft.com>
Tested-by: NKirill A. Shutemov <kirill.shutemov@linux.intel.com>
Cc: Konstantin Khlebnikov <koct9i@gmail.com>
Cc: Ross Zwisler <ross.zwisler@linux.intel.com>
Cc: Matthew Wilcox <mawilcox@microsoft.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

Instead of reseeding the random number generator every time around the
loop in big_gang_check(), seed it at the beginning of execution.  Use
rand_r() and an independent base seed for each thread in
iteration_test() so they don't stomp all over each others state.  Since
this particular test depends on the kernel scheduler, the iteration test
can't be reproduced based purely on the random seed, but at least it
won't pollute the other tests.

Print the seed, and allow the seed to be specified so that a run which
hits a problem can be reproduced.

Link: http://lkml.kernel.org/r/1480369871-5271-41-git-send-email-mawilcox@linuxonhyperv.comSigned-off-by: NMatthew Wilcox <willy@infradead.org>
Tested-by: NKirill A. Shutemov <kirill.shutemov@linux.intel.com>
Cc: Konstantin Khlebnikov <koct9i@gmail.com>
Cc: Ross Zwisler <ross.zwisler@linux.intel.com>
Cc: Matthew Wilcox <mawilcox@microsoft.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

It can be a source of mild concern when the test suite shows that we're
leaking nodes.  While poring over the source code looking for leaks can
lead to some fascinating bugs being discovered, sometimes the leak is
simply that these nodes were preallocated and are sitting on the per-CPU
list.  Free them by calling the CPU dead callback.

Link: http://lkml.kernel.org/r/1480369871-5271-40-git-send-email-mawilcox@linuxonhyperv.comSigned-off-by: NMatthew Wilcox <willy@infradead.org>
Tested-by: NKirill A. Shutemov <kirill.shutemov@linux.intel.com>
Cc: Konstantin Khlebnikov <koct9i@gmail.com>
Cc: Ross Zwisler <ross.zwisler@linux.intel.com>
Cc: Matthew Wilcox <mawilcox@microsoft.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

Rather than simply NOP out preempt_enable() and preempt_disable(), keep
track of preempt_count and display it regularly in case either the test
suite or the code under test is forgetting to balance the enables &
disables.  Only found a test-case that was forgetting to re-enable
preemption, but it's a possibility worth checking.

Link: http://lkml.kernel.org/r/1480369871-5271-39-git-send-email-mawilcox@linuxonhyperv.comSigned-off-by: NMatthew Wilcox <willy@infradead.org>
Tested-by: NKirill A. Shutemov <kirill.shutemov@linux.intel.com>
Cc: Konstantin Khlebnikov <koct9i@gmail.com>
Cc: Ross Zwisler <ross.zwisler@linux.intel.com>
Cc: Matthew Wilcox <mawilcox@microsoft.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

In order to test the preload code, it is necessary to fail GFP_ATOMIC
allocations, which requires defining GFP_KERNEL and GFP_ATOMIC properly.
Remove the obsolete __GFP_WAIT and copy the definitions of the __GFP
flags which are used from the kernel include files.  We also need the
real definition of gfpflags_allow_blocking() to persuade the radix tree
to actually use its preallocated nodes.

Link: http://lkml.kernel.org/r/1480369871-5271-38-git-send-email-mawilcox@linuxonhyperv.comSigned-off-by: NMatthew Wilcox <willy@linux.intel.com>
Tested-by: NKirill A. Shutemov <kirill.shutemov@linux.intel.com>
Cc: Konstantin Khlebnikov <koct9i@gmail.com>
Cc: Ross Zwisler <ross.zwisler@linux.intel.com>
Cc: Matthew Wilcox <mawilcox@microsoft.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

Patch series "Radix tree patches for 4.10", v3.

Mostly these are improvements; the only bug fixes in here relate to
multiorder entries (which are unused in the 4.9 tree).

This patch (of 32):

The radix tree uses its own buggy WARN_ON_ONCE.  Replace it with the
definition from asm-generic/bug.h

Link: http://lkml.kernel.org/r/1480369871-5271-37-git-send-email-mawilcox@linuxonhyperv.comSigned-off-by: NMatthew Wilcox <willy@linux.intel.com>
Tested-by: NKirill A. Shutemov <kirill.shutemov@linux.intel.com>
Cc: Konstantin Khlebnikov <koct9i@gmail.com>
Cc: Ross Zwisler <ross.zwisler@linux.intel.com>
Cc: Matthew Wilcox <mawilcox@microsoft.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

Currently we never clear dirty tags in DAX mappings and thus address
ranges to flush accumulate.  Now that we have locking of radix tree
entries, we have all the locking necessary to reliably clear the radix
tree dirty tag when flushing caches for corresponding address range.
Similarly to page_mkclean() we also have to write-protect pages to get a
page fault when the page is next written to so that we can mark the
entry dirty again.

Link: http://lkml.kernel.org/r/1479460644-25076-21-git-send-email-jack@suse.czSigned-off-by: NJan Kara <jack@suse.cz>
Reviewed-by: NRoss Zwisler <ross.zwisler@linux.intel.com>
Cc: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Cc: Dan Williams <dan.j.williams@intel.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

Currently PTE gets updated in wp_pfn_shared() after dax_pfn_mkwrite()
has released corresponding radix tree entry lock.  When we want to
writeprotect PTE on cache flush, we need PTE modification to happen
under radix tree entry lock to ensure consistent updates of PTE and
radix tree (standard faults use page lock to ensure this consistency).
So move update of PTE bit into dax_pfn_mkwrite().

Link: http://lkml.kernel.org/r/1479460644-25076-20-git-send-email-jack@suse.czSigned-off-by: NJan Kara <jack@suse.cz>
Reviewed-by: NRoss Zwisler <ross.zwisler@linux.intel.com>
Cc: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Cc: Dan Williams <dan.j.williams@intel.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

Currently, flushing of caches for DAX mappings was ignoring entry lock.
So far this was ok (modulo a bug that a difference in entry lock could
cause cache flushing to be mistakenly skipped) but in the following
patches we will write-protect PTEs on cache flushing and clear dirty
tags.  For that we will need more exclusion.  So do cache flushing under
an entry lock.  This allows us to remove one lock-unlock pair of
mapping->tree_lock as a bonus.

Link: http://lkml.kernel.org/r/1479460644-25076-19-git-send-email-jack@suse.czSigned-off-by: NJan Kara <jack@suse.cz>
Reviewed-by: NRoss Zwisler <ross.zwisler@linux.intel.com>
Cc: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Cc: Dan Williams <dan.j.williams@intel.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

DAX will need to implement its own version of page_check_address().  To
avoid duplicating page table walking code, export follow_pte() which
does what we need.

Link: http://lkml.kernel.org/r/1479460644-25076-18-git-send-email-jack@suse.czSigned-off-by: NJan Kara <jack@suse.cz>
Reviewed-by: NRoss Zwisler <ross.zwisler@linux.intel.com>
Cc: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Cc: Dan Williams <dan.j.williams@intel.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

Currently finish_mkwrite_fault() returns 0 when PTE got changed before
we acquired PTE lock and VM_FAULT_WRITE when we succeeded in modifying
the PTE.  This is somewhat confusing since 0 generally means success, it
is also inconsistent with finish_fault() which returns 0 on success.
Change finish_mkwrite_fault() to return 0 on success and VM_FAULT_NOPAGE
when PTE changed.  Practically, there should be no behavioral difference
since we bail out from the fault the same way regardless whether we
return 0, VM_FAULT_NOPAGE, or VM_FAULT_WRITE.  Also note that
VM_FAULT_WRITE has no effect for shared mappings since the only two
places that check it - KSM and GUP - care about private mappings only.
Generally the meaning of VM_FAULT_WRITE for shared mappings is not well
defined and we should probably clean that up.

Link: http://lkml.kernel.org/r/1479460644-25076-17-git-send-email-jack@suse.czSigned-off-by: NJan Kara <jack@suse.cz>
Acked-by: NKirill A. Shutemov <kirill.shutemov@linux.intel.com>
Cc: Ross Zwisler <ross.zwisler@linux.intel.com>
Cc: Dan Williams <dan.j.williams@intel.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

Provide a helper function for finishing write faults due to PTE being
read-only.  The helper will be used by DAX to avoid the need of
complicating generic MM code with DAX locking specifics.

Link: http://lkml.kernel.org/r/1479460644-25076-16-git-send-email-jack@suse.czSigned-off-by: NJan Kara <jack@suse.cz>
Reviewed-by: NRoss Zwisler <ross.zwisler@linux.intel.com>
Acked-by: NKirill A. Shutemov <kirill.shutemov@linux.intel.com>
Cc: Dan Williams <dan.j.williams@intel.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

wp_page_reuse() handles write shared faults which is needed only in
wp_page_shared().  Move the handling only into that location to make
wp_page_reuse() simpler and avoid a strange situation when we sometimes
pass in locked page, sometimes unlocked etc.

Link: http://lkml.kernel.org/r/1479460644-25076-15-git-send-email-jack@suse.czSigned-off-by: NJan Kara <jack@suse.cz>
Reviewed-by: NRoss Zwisler <ross.zwisler@linux.intel.com>
Acked-by: NKirill A. Shutemov <kirill.shutemov@linux.intel.com>
Cc: Dan Williams <dan.j.williams@intel.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

So far we set vmf->page during WP faults only when we needed to pass it
to the ->page_mkwrite handler.  Set it in all the cases now and use that
instead of passing page pointer explicitly around.

Link: http://lkml.kernel.org/r/1479460644-25076-14-git-send-email-jack@suse.czSigned-off-by: NJan Kara <jack@suse.cz>
Reviewed-by: NRoss Zwisler <ross.zwisler@linux.intel.com>
Acked-by: NKirill A. Shutemov <kirill.shutemov@linux.intel.com>
Cc: Dan Williams <dan.j.williams@intel.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

We will need more information in the ->page_mkwrite() helper for DAX to
be able to fully finish faults there.  Pass vm_fault structure to
do_page_mkwrite() and use it there so that information propagates
properly from upper layers.

Link: http://lkml.kernel.org/r/1479460644-25076-13-git-send-email-jack@suse.czSigned-off-by: NJan Kara <jack@suse.cz>
Reviewed-by: NRoss Zwisler <ross.zwisler@linux.intel.com>
Acked-by: NKirill A. Shutemov <kirill.shutemov@linux.intel.com>
Cc: Dan Williams <dan.j.williams@intel.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

Currently we duplicate handling of shared write faults in
wp_page_reuse() and do_shared_fault().  Factor them out into a common
function.

Link: http://lkml.kernel.org/r/1479460644-25076-12-git-send-email-jack@suse.czSigned-off-by: NJan Kara <jack@suse.cz>
Reviewed-by: NRoss Zwisler <ross.zwisler@linux.intel.com>
Acked-by: NKirill A. Shutemov <kirill.shutemov@linux.intel.com>
Cc: Dan Williams <dan.j.williams@intel.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

Move final handling of COW faults from generic code into DAX fault
handler.  That way generic code doesn't have to be aware of
peculiarities of DAX locking so remove that knowledge and make locking
functions private to fs/dax.c.

Link: http://lkml.kernel.org/r/1479460644-25076-11-git-send-email-jack@suse.czSigned-off-by: NJan Kara <jack@suse.cz>
Acked-by: NKirill A. Shutemov <kirill.shutemov@linux.intel.com>
Reviewed-by: NRoss Zwisler <ross.zwisler@linux.intel.com>
Cc: Dan Williams <dan.j.williams@intel.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

Introduce finish_fault() as a helper function for finishing page faults.
It is rather thin wrapper around alloc_set_pte() but since we'd want to
call this from DAX code or filesystems, it is still useful to avoid some
boilerplate code.

Link: http://lkml.kernel.org/r/1479460644-25076-10-git-send-email-jack@suse.czSigned-off-by: NJan Kara <jack@suse.cz>
Reviewed-by: NRoss Zwisler <ross.zwisler@linux.intel.com>
Acked-by: NKirill A. Shutemov <kirill.shutemov@linux.intel.com>
Cc: Dan Williams <dan.j.williams@intel.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

Patch series "dax: Clear dirty bits after flushing caches", v5.

Patchset to clear dirty bits from radix tree of DAX inodes when caches
for corresponding pfns have been flushed.  In principle, these patches
enable handlers to easily update PTEs and do other work necessary to
finish the fault without duplicating the functionality present in the
generic code.  I'd like to thank Kirill and Ross for reviews of the
series!

This patch (of 20):

To allow full handling of COW faults add memcg field to struct vm_fault
and a return value of ->fault() handler meaning that COW fault is fully
handled and memcg charge must not be canceled.  This will allow us to
remove knowledge about special DAX locking from the generic fault code.

Link: http://lkml.kernel.org/r/1479460644-25076-9-git-send-email-jack@suse.czSigned-off-by: NJan Kara <jack@suse.cz>
Reviewed-by: NRoss Zwisler <ross.zwisler@linux.intel.com>
Acked-by: NKirill A. Shutemov <kirill.shutemov@linux.intel.com>
Cc: Dan Williams <dan.j.williams@intel.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>