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* XArray: Fix xa_reserve for 2-byte aligned entriesMatthew Wilcox2019-02-211-3/+5
| | | | | | | | If we reserve index 0, the next entry to be stored there might be 2-byte aligned. That means we have to create the root xa_node at the time of reserving the initial entry. Signed-off-by: Matthew Wilcox <willy@infradead.org>
* XArray: Fix xa_erase of 2-byte aligned entriesMatthew Wilcox2019-02-211-1/+1
| | | | | | | | xas_store() was interpreting the entry it found in the array as a node entry if the bottom two bits had value 2. That's only true if either the entry is in the root node or in a non-leaf node. Signed-off-by: Matthew Wilcox <willy@infradead.org>
* XArray: Use xa_cmpxchg to implement xa_reserveMatthew Wilcox2019-02-201-36/+0
| | | | | | | | Jason feels this is clearer, and it saves a function and an exported symbol. Suggested-by: Jason Gunthorpe <jgg@ziepe.ca> Signed-off-by: Matthew Wilcox <willy@infradead.org>
* XArray: Fix xa_release in allocating arraysMatthew Wilcox2019-02-201-5/+1
| | | | | | | | | | | | | | xa_cmpxchg() was a little too magic in turning ZERO entries into NULL, and would leave the entry set to the ZERO entry instead of releasing it for future use. After careful review of existing users of xa_cmpxchg(), change the semantics so that it does not translate either incoming argument from NULL into ZERO entries. Add several tests to the test-suite to make sure this problem doesn't come back. Reported-by: Jason Gunthorpe <jgg@ziepe.ca> Signed-off-by: Matthew Wilcox <willy@infradead.org>
* XArray: Add cyclic allocationMatthew Wilcox2019-02-061-0/+50
| | | | | | | | | | | | | | | | | | This differs slightly from the IDR equivalent in five ways. 1. It can allocate up to UINT_MAX instead of being limited to INT_MAX, like xa_alloc(). Also like xa_alloc(), it will write to the 'id' pointer before placing the entry in the XArray. 2. The 'next' cursor is allocated separately from the XArray instead of being part of the IDR. This saves memory for all the users which do not use the cyclic allocation API and suits some users better. 3. It returns -EBUSY instead of -ENOSPC. 4. It will attempt to wrap back to the minimum value on memory allocation failure as well as on an -EBUSY error, assuming that a user would rather allocate a small ID than suffer an ID allocation failure. 5. It reports whether it has wrapped, which is important to some users. Signed-off-by: Matthew Wilcox <willy@infradead.org>
* XArray: Redesign xa_alloc APIMatthew Wilcox2019-02-061-15/+14
| | | | | | | | | | It was too easy to forget to initialise the start index. Add an xa_limit data structure which can be used to pass min & max, and define a couple of special values for common cases. Also add some more tests cribbed from the IDR test suite. Change the return value from -ENOSPC to -EBUSY to match xa_insert(). Signed-off-by: Matthew Wilcox <willy@infradead.org>
* XArray: Add support for 1s-based allocationMatthew Wilcox2019-02-061-0/+11
| | | | | | | | | | | A lot of places want to allocate IDs starting at 1 instead of 0. While the xa_alloc() API supports this, it's not very efficient if lots of IDs are allocated, due to having to walk down to the bottom of the tree to see if ID 1 is available, then all the way over to the next non-allocated ID. This method marks ID 0 as being occupied which wastes one slot in the XArray, but preserves xa_empty() as working. Signed-off-by: Matthew Wilcox <willy@infradead.org>
* XArray: Change xa_insert to return -EBUSYMatthew Wilcox2019-02-061-2/+2
| | | | | | | | Userspace translates EEXIST to "File exists" which isn't a very good error message for the problem. "Device or resource busy" is a better indication of what went wrong. Signed-off-by: Matthew Wilcox <willy@infradead.org>
* XArray: Update xa_erase family descriptionsMatthew Wilcox2019-02-041-9/+8
| | | | | | | xa_erase does not allocate memory and doesn't have a gfp parameter. Update the descriptions of all four variants to be more useful. Signed-off-by: Matthew Wilcox <willy@infradead.org>
* XArray: Honour reserved entries in xa_insertMatthew Wilcox2019-01-061-0/+41
| | | | | | | | | xa_insert() should treat reserved entries as occupied, not as available. Also, it should treat requests to insert a NULL pointer as a request to reserve the slot. Add xa_insert_bh() and xa_insert_irq() for completeness. Signed-off-by: Matthew Wilcox <willy@infradead.org>
* XArray: Permit storing 2-byte-aligned pointersMatthew Wilcox2019-01-061-9/+13
| | | | | | | | On m68k, statically allocated pointers may only be two-byte aligned. This clashes with the XArray's method for tagging internal pointers. Permit storing these pointers in single slots (ie not in multislots). Signed-off-by: Matthew Wilcox <willy@infradead.org>
* XArray: Turn xa_init_flags into a static inlineMatthew Wilcox2019-01-061-29/+0
| | | | | | | | | | | | A regular xa_init_flags() put all dynamically-initialised XArrays into the same locking class. That leads to lockdep believing that taking one XArray lock while holding another is a deadlock. It's possible to work around some of these situations with separate locking classes for irq/bh/regular XArrays, and SINGLE_DEPTH_NESTING, but that's ugly, and it doesn't work for all situations (where we have completely unrelated XArrays). Signed-off-by: Matthew Wilcox <willy@infradead.org>
* XArray: Fix xa_alloc when id exceeds maxMatthew Wilcox2018-12-131-5/+3
| | | | | | | | | | Specifying a starting ID greater than the maximum ID isn't something attempted very often, but it should fail. It was succeeding due to xas_find_marked() returning the wrong error state, so add tests for both xa_alloc() and xas_find_marked(). Fixes: b803b42823d0 ("xarray: Add XArray iterators") Signed-off-by: Matthew Wilcox <willy@infradead.org>
* XArray: Correct xa_store_rangeMatthew Wilcox2018-11-161-2/+3
| | | | | | | 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>
* XArray: Fix DocumentationMatthew Wilcox2018-11-051-5/+5
| | | | | | Minor fixes. Signed-off-by: Matthew Wilcox <willy@infradead.org>
* XArray: Handle NULL pointers differently for allocationMatthew Wilcox2018-11-051-3/+10
| | | | | | | | | 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>
* XArray: Unify xa_store and __xa_storeMatthew Wilcox2018-11-051-33/+25
| | | | | | | 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>
* XArray: Turn xa_erase into an exported functionMatthew Wilcox2018-11-051-0/+24
| | | | | | | 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>
* XArray: Unify xa_cmpxchg and __xa_cmpxchgMatthew Wilcox2018-11-051-41/+0
| | | | | | | | | 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>
* XArray: Regularise xa_reserveMatthew Wilcox2018-11-051-11/+7
| | | | | | | | 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>
* XArray: Export __xa_foo to non-GPL modulesMatthew Wilcox2018-11-051-3/+3
| | | | | | | Without this, it's not possible to use static inlines like xa_store_bh() and xa_erase_irq(). Signed-off-by: Matthew Wilcox <willy@infradead.org>
* XArray: Fix xa_for_each with a single element at 0Matthew Wilcox2018-11-051-0/+2
| | | | | | | | | | | | | | | | 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>
* xarray: Add range store functionalityMatthew Wilcox2018-10-211-2/+95
| | | | | | | | | 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>
* xarray: Track free entries in an XArrayMatthew Wilcox2018-10-211-4/+84
| | | | | | | 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>
* xarray: Add xa_reserve and xa_releaseMatthew Wilcox2018-10-211-0/+47
| | | | | | | | 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>
* xarray: Add xas_create_rangeMatthew Wilcox2018-10-211-0/+50
| | | | | | | 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>
* xarray: Add xas_for_each_conflictMatthew Wilcox2018-10-211-0/+61
| | | | | | | | | 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>
* xarray: Step through an XArrayMatthew Wilcox2018-10-211-0/+74
| | | | | | | | | 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>
* xarray: Destroy an XArrayMatthew Wilcox2018-10-211-0/+28
| | | | | | | 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>
* xarray: Extract entries from an XArrayMatthew Wilcox2018-10-211-0/+80
| | | | | | | | 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>
* xarray: Add XArray iteratorsMatthew Wilcox2018-10-211-0/+292
| | | | | | | | | | | | | | 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>
* xarray: Add XArray conditional store operationsMatthew Wilcox2018-10-211-0/+71
| | | | | | | | | | 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>
* xarray: Add XArray unconditional store operationsMatthew Wilcox2018-10-211-0/+693
| | | | | | | | | | | | | | | | | | | | 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: Add XArray marksMatthew Wilcox2018-10-211-2/+230
| | | | | | | | 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>
* xarray: Add XArray load operationMatthew Wilcox2018-10-211-0/+195
| | | | | | | | | | | | | 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>
* xarray: Add definition of struct xarrayMatthew Wilcox2018-10-211-0/+44
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>
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