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xarray: add the xa_lock to the radix_tree_root 

This results in no change in structure size on 64-bit machines as it
fits in the padding between the gfp_t and the void *.  32-bit machines
will grow the structure from 8 to 12 bytes.  Almost all radix trees are
protected with (at least) a spinlock, so as they are converted from
radix trees to xarrays, the data structures will shrink again.

Initialising the spinlock requires a name for the benefit of lockdep, so
RADIX_TREE_INIT() now needs to know the name of the radix tree it's
initialising, and so do IDR_INIT() and IDA_INIT().

Also add the xa_lock() and xa_unlock() family of wrappers to make it
easier to use the lock.  If we could rely on -fplan9-extensions in the
compiler, we could avoid all of this syntactic sugar, but that wasn't
added until gcc 4.6.

Link: http://lkml.kernel.org/r/20180313132639.17387-8-willy@infradead.org
Signed-off-by: Matthew Wilcox <mawilcox@microsoft.com>
Reviewed-by: Jeff Layton <jlayton@kernel.org>
Cc: Darrick J. Wong <darrick.wong@oracle.com>
Cc: Dave Chinner <david@fromorbit.com>
Cc: Ryusuke Konishi <konishi.ryusuke@lab.ntt.co.jp>
Cc: Will Deacon <will.deacon@arm.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This commit is contained in:
Matthew Wilcox 2018-04-10 16:36:52 -07:00 committed by Linus Torvalds
parent e5a9554196
commit f6bb2a2c0b
6 changed files with 42 additions and 13 deletions
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2
fs/f2fs/gc.c
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@ -1015,7 +1015,7 @@ int f2fs_gc(struct f2fs_sb_info *sbi, bool sync,
unsigned int init_segno = segno;
struct gc_inode_list gc_list = {
.ilist = LIST_HEAD_INIT(gc_list.ilist),
.iroot = RADIX_TREE_INIT(GFP_NOFS),
.iroot = RADIX_TREE_INIT(gc_list.iroot, GFP_NOFS),
};
trace_f2fs_gc_begin(sbi->sb, sync, background,

19
include/linux/idr.h
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@ -32,27 +32,28 @@ struct idr {
#define IDR_RT_MARKER (ROOT_IS_IDR | (__force gfp_t) \
(1 << (ROOT_TAG_SHIFT + IDR_FREE)))
#define IDR_INIT_BASE(base) { \
.idr_rt = RADIX_TREE_INIT(IDR_RT_MARKER), \
#define IDR_INIT_BASE(name, base) { \
.idr_rt = RADIX_TREE_INIT(name, IDR_RT_MARKER), \
.idr_base = (base), \
.idr_next = 0, \
}
/**
* IDR_INIT() - Initialise an IDR.
* @name: Name of IDR.
*
* A freshly-initialised IDR contains no IDs.
*/
#define IDR_INIT IDR_INIT_BASE(0)
#define IDR_INIT(name) IDR_INIT_BASE(name, 0)
/**
* DEFINE_IDR() - Define a statically-allocated IDR
* @name: Name of IDR
* DEFINE_IDR() - Define a statically-allocated IDR.
* @name: Name of IDR.
*
* An IDR defined using this macro is ready for use with no additional
* initialisation required. It contains no IDs.
*/
#define DEFINE_IDR(name) struct idr name = IDR_INIT
#define DEFINE_IDR(name) struct idr name = IDR_INIT(name)
/**
* idr_get_cursor - Return the current position of the cyclic allocator
@ -219,10 +220,10 @@ struct ida {
struct radix_tree_root ida_rt;
};
#define IDA_INIT { \
.ida_rt = RADIX_TREE_INIT(IDR_RT_MARKER | GFP_NOWAIT), \
#define IDA_INIT(name) { \
.ida_rt = RADIX_TREE_INIT(name, IDR_RT_MARKER | GFP_NOWAIT), \
}
#define DEFINE_IDA(name) struct ida name = IDA_INIT
#define DEFINE_IDA(name) struct ida name = IDA_INIT(name)
int ida_pre_get(struct ida *ida, gfp_t gfp_mask);
int ida_get_new_above(struct ida *ida, int starting_id, int *p_id);

7
include/linux/radix-tree.h
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@ -110,20 +110,23 @@ struct radix_tree_node {
#define ROOT_TAG_SHIFT (__GFP_BITS_SHIFT)
struct radix_tree_root {
spinlock_t xa_lock;
gfp_t gfp_mask;
struct radix_tree_node __rcu *rnode;
};
#define RADIX_TREE_INIT(mask) { \
#define RADIX_TREE_INIT(name, mask) { \
.xa_lock = __SPIN_LOCK_UNLOCKED(name.xa_lock), \
.gfp_mask = (mask), \
.rnode = NULL, \
}
#define RADIX_TREE(name, mask) \
struct radix_tree_root name = RADIX_TREE_INIT(mask)
struct radix_tree_root name = RADIX_TREE_INIT(name, mask)
#define INIT_RADIX_TREE(root, mask) \
do { \
spin_lock_init(&(root)->xa_lock); \
(root)->gfp_mask = (mask); \
(root)->rnode = NULL; \
} while (0)

24
include/linux/xarray.h Normal file
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@ -0,0 +1,24 @@
/* SPDX-License-Identifier: GPL-2.0+ */
#ifndef _LINUX_XARRAY_H
#define _LINUX_XARRAY_H
/*
* eXtensible Arrays
* Copyright (c) 2017 Microsoft Corporation
* Author: Matthew Wilcox <mawilcox@microsoft.com>
*/
#include <linux/spinlock.h>
#define xa_trylock(xa) spin_trylock(&(xa)->xa_lock)
#define xa_lock(xa) spin_lock(&(xa)->xa_lock)
#define xa_unlock(xa) spin_unlock(&(xa)->xa_lock)
#define xa_lock_bh(xa) spin_lock_bh(&(xa)->xa_lock)
#define xa_unlock_bh(xa) spin_unlock_bh(&(xa)->xa_lock)
#define xa_lock_irq(xa) spin_lock_irq(&(xa)->xa_lock)
#define xa_unlock_irq(xa) spin_unlock_irq(&(xa)->xa_lock)
#define xa_lock_irqsave(xa, flags) \
spin_lock_irqsave(&(xa)->xa_lock, flags)
#define xa_unlock_irqrestore(xa, flags) \
spin_unlock_irqrestore(&(xa)->xa_lock, flags)
#endif /* _LINUX_XARRAY_H */

2
kernel/pid.c
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@ -70,7 +70,7 @@ int pid_max_max = PID_MAX_LIMIT;
*/
struct pid_namespace init_pid_ns = {
.kref = KREF_INIT(2),
.idr = IDR_INIT,
.idr = IDR_INIT(init_pid_ns.idr),
.pid_allocated = PIDNS_ADDING,
.level = 0,
.child_reaper = &init_task,

1
tools/include/linux/spinlock.h
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@ -7,6 +7,7 @@
#define spinlock_t pthread_mutex_t
#define DEFINE_SPINLOCK(x) pthread_mutex_t x = PTHREAD_MUTEX_INITIALIZER;
#define __SPIN_LOCK_UNLOCKED(x) (pthread_mutex_t)PTHREAD_MUTEX_INITIALIZER
#define spin_lock_irqsave(x, f) (void)f, pthread_mutex_lock(x)
#define spin_unlock_irqrestore(x, f) (void)f, pthread_mutex_unlock(x)