The explicit '64' should have been BITS_PER_LONG, but while looking at
this code I realised I meant to use __ffs(), not ilog2().
Signed-off-by: Matthew Wilcox <willy@infradead.org>
For allocating XArrays, it makes sense to distinguish beteen erasing an
entry and storing NULL. Storing NULL keeps the index allocated with a
NULL pointer associated with it while xa_erase() frees the index. Some
existing IDR users rely on this ability.
Signed-off-by: Matthew Wilcox <willy@infradead.org>
Saves around 115 bytes on a tinyconfig build and reduces the amount
of code duplication in the XArray implementation.
Signed-off-by: Matthew Wilcox <willy@infradead.org>
Make xa_erase() take the spinlock and then call __xa_erase(), but make
it out of line since it's such a common function.
Signed-off-by: Matthew Wilcox <willy@infradead.org>
xa_cmpxchg() was one of the largest functions in the xarray
implementation. By turning it into a wrapper and having the callers
take the lock (like several other functions), we save 160 bytes on a
tinyconfig build and reduce the duplication in xarray.c.
Signed-off-by: Matthew Wilcox <willy@infradead.org>
The xa_reserve() function was a little unusual in that it attempted to
be callable for all kinds of locking scenarios. Make it look like the
other APIs with __xa_reserve, xa_reserve_bh and xa_reserve_irq variants.
Signed-off-by: Matthew Wilcox <willy@infradead.org>
The following sequence of calls would result in an infinite loop in
xa_find_after():
xa_store(xa, 0, x, GFP_KERNEL);
index = 0;
xa_for_each(xa, entry, index, ULONG_MAX, XA_PRESENT) { }
xa_find_after() was confusing the situation where we found no entry in
the tree with finding a multiorder entry, so it would look for the
successor entry forever. Just check for this case explicitly. Includes
a few new checks in the test suite to be sure this doesn't reappear.
Signed-off-by: Matthew Wilcox <willy@infradead.org>
This version of xa_store_range() really only supports load and store.
Our only user only needs basic load and store functionality, so there's
no need to do the extra work to support marking and overlapping stores
correctly yet.
Signed-off-by: Matthew Wilcox <willy@infradead.org>
Add the optional ability to track which entries in an XArray are free
and provide xa_alloc() to replace most of the functionality of the IDR.
Signed-off-by: Matthew Wilcox <willy@infradead.org>
This function reserves a slot in the XArray for users which need
to acquire multiple locks before storing their entry in the tree and
so cannot use a plain xa_store().
Signed-off-by: Matthew Wilcox <willy@infradead.org>
This hopefully temporary function is useful for users who have not yet
been converted to multi-index entries.
Signed-off-by: Matthew Wilcox <willy@infradead.org>
This iterator iterates over each entry that is stored in the index or
indices specified by the xa_state. This is intended for use for a
conditional store of a multiindex entry, or to allow entries which are
about to be removed from the xarray to be disposed of properly.
Signed-off-by: Matthew Wilcox <willy@infradead.org>
The xas_next and xas_prev functions move the xas index by one position,
and adjust the rest of the iterator state to match it. This is more
efficient than calling xas_set() as it keeps the iterator at the leaves
of the tree instead of walking the iterator from the root each time.
Signed-off-by: Matthew Wilcox <willy@infradead.org>
This function frees all the internal memory allocated to the xarray
and reinitialises it to be empty.
Signed-off-by: Matthew Wilcox <willy@infradead.org>
The xa_extract function combines the functionality of
radix_tree_gang_lookup() and radix_tree_gang_lookup_tagged().
It extracts entries matching the specified filter into a normal array.
Signed-off-by: Matthew Wilcox <willy@infradead.org>
The xa_for_each iterator allows the user to efficiently walk a range
of the array, executing the loop body once for each entry in that
range that matches the filter. This commit also includes xa_find()
and xa_find_after() which are helper functions for xa_for_each() but
may also be useful in their own right.
In the xas family of functions, we have xas_for_each(), xas_find(),
xas_next_entry(), xas_for_each_tagged(), xas_find_tagged(),
xas_next_tagged() and xas_pause().
Signed-off-by: Matthew Wilcox <willy@infradead.org>
Like cmpxchg(), xa_cmpxchg will only store to the index if the current
entry matches the old entry. It returns the current entry, which is
usually more useful than the errno returned by radix_tree_insert().
For the users who really only want the errno, the xa_insert() wrapper
provides a more convenient calling convention.
Signed-off-by: Matthew Wilcox <willy@infradead.org>
xa_store() differs from radix_tree_insert() in that it will overwrite an
existing element in the array rather than returning an error. This is
the behaviour which most users want, and those that want more complex
behaviour generally want to use the xas family of routines anyway.
For memory allocation, xa_store() will first attempt to request memory
from the slab allocator; if memory is not immediately available, it will
drop the xa_lock and allocate memory, keeping a pointer in the xa_state.
It does not use the per-CPU cache, although those will continue to exist
until all radix tree users are converted to the xarray.
This patch also includes xa_erase() and __xa_erase() for a streamlined
way to store NULL. Since there is no need to allocate memory in order
to store a NULL in the XArray, we do not need to trouble the user with
deciding what memory allocation flags to use.
Signed-off-by: Matthew Wilcox <willy@infradead.org>
XArray marks are like the radix tree tags, only slightly more strongly
typed. They are renamed in order to distinguish them from tagged
pointers. This commit adds the basic get/set/clear operations.
Signed-off-by: Matthew Wilcox <willy@infradead.org>
The xa_load function brings with it a lot of infrastructure; xa_empty(),
xa_is_err(), and large chunks of the XArray advanced API that are used
to implement xa_load.
As the test-suite demonstrates, it is possible to use the XArray functions
on a radix tree. The radix tree functions depend on the GFP flags being
stored in the root of the tree, so it's not possible to use the radix
tree functions on an XArray.
Signed-off-by: Matthew Wilcox <willy@infradead.org>
This is a direct replacement for struct radix_tree_root. Some of the
struct members have changed name; convert those, and use a #define so
that radix_tree users continue to work without change.
Signed-off-by: Matthew Wilcox <willy@infradead.org>
Reviewed-by: Josef Bacik <jbacik@fb.com>
