Instead of using a pagevec, just use the XArray iterators.  Add a
conditional rescheduling point which probably should have been there in
the original.
Signed-off-by: Matthew Wilcox <willy@infradead.org>

Add some XArray-based helper functions to replace the radix tree based
metaphors currently in use.  The biggest change is that converted code
doesn't see its own lock bit; get_unlocked_entry() always returns an
entry with the lock bit clear.  So we don't have to mess around loading
the current entry and clearing the lock bit; we can just store the
unlocked entry that we already have.
Signed-off-by: Matthew Wilcox <willy@infradead.org>

Since the XArray is embedded in the struct address_space, its address
contains exactly as much entropy as the address of the mapping.  This
patch is purely preparatory for later patches which will simplify the
wait/wake interfaces.
Signed-off-by: Matthew Wilcox <willy@infradead.org>

Remove mentions of 'radix' and 'radix tree'.  Simplify some names by
dropping the word 'mapping'.
Signed-off-by: Matthew Wilcox <willy@infradead.org>

This is a straightforward conversion.
Signed-off-by: Matthew Wilcox <willy@infradead.org>

This is close to a 1:1 replacement of radix tree APIs with their XArray
equivalents.  It would be possible to optimise nilfs_copy_back_pages(),
but that doesn't seem to be in the performance path.  Also, I think
it has a pre-existing bug, and I've added a note to that effect in the
source code.
Signed-off-by: Matthew Wilcox <willy@infradead.org>

A couple of short loops.
Signed-off-by: Matthew Wilcox <willy@infradead.org>

Mostly comment fixes, but one use of __xa_set_mark.
Signed-off-by: Matthew Wilcox <willy@infradead.org>

Signed-off-by: Matthew Wilcox <willy@infradead.org>
Acked-by: David Sterba <dsterba@suse.com>

Remove the last mentions of radix tree from various comments.
Signed-off-by: Matthew Wilcox <willy@infradead.org>

Switch to a batch-processing model like memfd_wait_for_pins() and
use the xa_state previously set up by memfd_wait_for_pins().
Signed-off-by: Matthew Wilcox <willy@infradead.org>
Reviewed-by: Mike Kravetz <mike.kravetz@oracle.com>

Simplify the locking by taking the spinlock while we walk the tree on
the assumption that many acquires and releases of the lock will be worse
than holding the lock while we process an entire batch of pages.
Signed-off-by: Matthew Wilcox <willy@infradead.org>
Reviewed-by: Mike Kravetz <mike.kravetz@oracle.com>

Simpler code because the xarray takes care of things like the limit and
dereferencing the slot.
Signed-off-by: Matthew Wilcox <willy@infradead.org>

Since we are conditionally storing NULL in the XArray, we do not need
to allocate memory and the GFP flags will be unused.
Signed-off-by: Matthew Wilcox <willy@infradead.org>

xa_find() is a slightly easier API to use than
radix_tree_gang_lookup_slot() because it contains its own RCU locking.
This commit removes the last user of radix_tree_gang_lookup_slot()
so remove the function too.
Signed-off-by: Matthew Wilcox <willy@infradead.org>

We can use xas_find_conflict() instead of radix_tree_gang_lookup_slot()
to find any conflicting entry and combine the three paths through this
function into one.
Signed-off-by: Matthew Wilcox <willy@infradead.org>

This is a 1:1 conversion.  The major part of this patch is converting
the test framework from userspace to kernel space and mirroring the
algorithm now used in find_swap_entry().
Signed-off-by: Matthew Wilcox <willy@infradead.org>

xa_load has its own RCU locking, so we can eliminate it here.
Signed-off-by: Matthew Wilcox <willy@infradead.org>

Rename shmem_radix_tree_replace() to shmem_replace_entry() and
convert it to use the XArray API.
Signed-off-by: Matthew Wilcox <willy@infradead.org>

Removes sparse warnings.
Signed-off-by: Matthew Wilcox <willy@infradead.org>

This is just a variable rename and comment change.
Signed-off-by: Matthew Wilcox <willy@infradead.org>

Slightly shorter and easier to read code.
Signed-off-by: Matthew Wilcox <willy@infradead.org>

I found another victim of the radix tree being hard to use.  Because
there was no call to radix_tree_preload(), khugepaged was allocating
radix_tree_nodes using GFP_ATOMIC.

I also converted a local_irq_save()/restore() pair to
disable()/enable().
Signed-off-by: Matthew Wilcox <willy@infradead.org>

Quite a straightforward conversion.
Signed-off-by: Matthew Wilcox <willy@infradead.org>

Signed-off-by: Matthew Wilcox <willy@infradead.org>

This one is trivial.
Signed-off-by: Matthew Wilcox <willy@infradead.org>

Both callers of __delete_from_swap_cache have the swp_entry_t already,
so pass that in to make constructing the XA_STATE easier.
Signed-off-by: Matthew Wilcox <willy@infradead.org>

Combine __add_to_swap_cache and add_to_swap_cache into one function
since there is no more need to preload.
Signed-off-by: Matthew Wilcox <willy@infradead.org>

This is essentially xa_cmpxchg() with the locking handled above us,
and it doesn't have to handle replacing a NULL entry.
Signed-off-by: Matthew Wilcox <willy@infradead.org>

We construct an XA_STATE and use it to delete the node with
xas_store() rather than adding a special function for this unique
use case.  Includes a test that simulates this usage for the
test suite.
Signed-off-by: Matthew Wilcox <willy@infradead.org>

Includes moving mapping_tagged() to fs.h as a static inline, and
changing it to return bool.
Signed-off-by: Matthew Wilcox <willy@infradead.org>

Instead of calling find_get_pages_range() and putting any reference,
use xas_find() to iterate over any entries in the range, skipping the
shadow/swap entries.
Signed-off-by: Matthew Wilcox <willy@infradead.org>

Signed-off-by: Matthew Wilcox <willy@infradead.org>

Rename the function from page_cache_tree_delete_batch to just
page_cache_delete_batch.
Signed-off-by: Matthew Wilcox <willy@infradead.org>

Now the page cache lookup is using the XArray, let's convert this
regression test from the radix tree API to the XArray so it's testing
roughly the same thing it was testing before.
Signed-off-by: Matthew Wilcox <willy@infradead.org>

Slight change of strategy here; if we have trouble getting hold of a
page for whatever reason (eg a compound page is split underneath us),
don't spin to stabilise the page, just continue the iteration, like we
would if we failed to trylock the page.  Since this is a speculative
optimisation, it feels like we should allow the process to take an extra
fault if it turns out to need this page instead of spending time to pin
down a page it may not need.
Signed-off-by: Matthew Wilcox <willy@infradead.org>

Slightly shorter and simpler code.
Signed-off-by: Matthew Wilcox <willy@infradead.org>

The 'end' parameter of the xas_for_each iterator avoids a useless
iteration at the end of the range.
Signed-off-by: Matthew Wilcox <willy@infradead.org>

There's no direct replacement for radix_tree_for_each_contig()
in the XArray API as it's an unusual thing to do.  Instead,
open-code a loop using xas_next().  This removes the only user of
radix_tree_for_each_contig() so delete the iterator from the API and
the test suite code for it.
Signed-off-by: Matthew Wilcox <willy@infradead.org>

The 'end' parameter of the xas_for_each iterator avoids a useless
iteration at the end of the range.
Signed-off-by: Matthew Wilcox <willy@infradead.org>