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authorMatthew Wilcox <willy@infradead.org>2017-11-03 13:30:42 -0400
committerMatthew Wilcox <willy@infradead.org>2018-09-29 22:47:49 -0400
commit3159f943aafdbacb2f94c38fdaadabf2bbde2a14 (patch)
tree7e06823a1ab7e90774535d17a217a939bdddda3b /include/linux/swapops.h
parent66ee620f06f99d72475db6eb638559ba608c7dee (diff)
xarray: Replace exceptional entries
Introduce xarray value entries and tagged pointers to replace radix tree exceptional entries. This is a slight change in encoding to allow the use of an extra bit (we can now store BITS_PER_LONG - 1 bits in a value entry). It is also a change in emphasis; exceptional entries are intimidating and different. As the comment explains, you can choose to store values or pointers in the xarray and they are both first-class citizens. Signed-off-by: Matthew Wilcox <willy@infradead.org> Reviewed-by: Josef Bacik <jbacik@fb.com>
Diffstat (limited to 'include/linux/swapops.h')
-rw-r--r--include/linux/swapops.h19
1 files changed, 7 insertions, 12 deletions
diff --git a/include/linux/swapops.h b/include/linux/swapops.h
index 22af9d8a84ae..4d961668e5fc 100644
--- a/include/linux/swapops.h
+++ b/include/linux/swapops.h
@@ -18,9 +18,8 @@
*
* swp_entry_t's are *never* stored anywhere in their arch-dependent format.
*/
-#define SWP_TYPE_SHIFT(e) ((sizeof(e.val) * 8) - \
- (MAX_SWAPFILES_SHIFT + RADIX_TREE_EXCEPTIONAL_SHIFT))
-#define SWP_OFFSET_MASK(e) ((1UL << SWP_TYPE_SHIFT(e)) - 1)
+#define SWP_TYPE_SHIFT (BITS_PER_XA_VALUE - MAX_SWAPFILES_SHIFT)
+#define SWP_OFFSET_MASK ((1UL << SWP_TYPE_SHIFT) - 1)
/*
* Store a type+offset into a swp_entry_t in an arch-independent format
@@ -29,8 +28,7 @@ static inline swp_entry_t swp_entry(unsigned long type, pgoff_t offset)
{
swp_entry_t ret;
- ret.val = (type << SWP_TYPE_SHIFT(ret)) |
- (offset & SWP_OFFSET_MASK(ret));
+ ret.val = (type << SWP_TYPE_SHIFT) | (offset & SWP_OFFSET_MASK);
return ret;
}
@@ -40,7 +38,7 @@ static inline swp_entry_t swp_entry(unsigned long type, pgoff_t offset)
*/
static inline unsigned swp_type(swp_entry_t entry)
{
- return (entry.val >> SWP_TYPE_SHIFT(entry));
+ return (entry.val >> SWP_TYPE_SHIFT);
}
/*
@@ -49,7 +47,7 @@ static inline unsigned swp_type(swp_entry_t entry)
*/
static inline pgoff_t swp_offset(swp_entry_t entry)
{
- return entry.val & SWP_OFFSET_MASK(entry);
+ return entry.val & SWP_OFFSET_MASK;
}
#ifdef CONFIG_MMU
@@ -90,16 +88,13 @@ static inline swp_entry_t radix_to_swp_entry(void *arg)
{
swp_entry_t entry;
- entry.val = (unsigned long)arg >> RADIX_TREE_EXCEPTIONAL_SHIFT;
+ entry.val = xa_to_value(arg);
return entry;
}
static inline void *swp_to_radix_entry(swp_entry_t entry)
{
- unsigned long value;
-
- value = entry.val << RADIX_TREE_EXCEPTIONAL_SHIFT;
- return (void *)(value | RADIX_TREE_EXCEPTIONAL_ENTRY);
+ return xa_mk_value(entry.val);
}
#if IS_ENABLED(CONFIG_DEVICE_PRIVATE)