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authorIngo Molnar <mingo@kernel.org>2018-02-06 21:12:31 +0100
committerIngo Molnar <mingo@kernel.org>2018-02-06 21:12:31 +0100
commit82845079160817cc6ac64e5321bbd935e0a47b3a (patch)
tree0886d1d52428e9db14536cae4b37db896e7c360a /include/linux/buffer_head.h
parent32e839dda3ba576943365f0f5817ce5c843137dc (diff)
parent68c5735eaa5e680e701c9a2d1e3c7880bdf5ab66 (diff)
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Merge branch 'linus' into sched/urgent, to resolve conflicts
Conflicts: arch/arm64/kernel/entry.S arch/x86/Kconfig include/linux/sched/mm.h kernel/fork.c Signed-off-by: Ingo Molnar <mingo@kernel.org>
Diffstat (limited to 'include/linux/buffer_head.h')
-rw-r--r--include/linux/buffer_head.h6
1 files changed, 4 insertions, 2 deletions
diff --git a/include/linux/buffer_head.h b/include/linux/buffer_head.h
index 8b1bf8d3d4a2..894e5d125de6 100644
--- a/include/linux/buffer_head.h
+++ b/include/linux/buffer_head.h
@@ -81,11 +81,14 @@ struct buffer_head {
/*
* macro tricks to expand the set_buffer_foo(), clear_buffer_foo()
* and buffer_foo() functions.
+ * To avoid reset buffer flags that are already set, because that causes
+ * a costly cache line transition, check the flag first.
*/
#define BUFFER_FNS(bit, name) \
static __always_inline void set_buffer_##name(struct buffer_head *bh) \
{ \
- set_bit(BH_##bit, &(bh)->b_state); \
+ if (!test_bit(BH_##bit, &(bh)->b_state)) \
+ set_bit(BH_##bit, &(bh)->b_state); \
} \
static __always_inline void clear_buffer_##name(struct buffer_head *bh) \
{ \
@@ -151,7 +154,6 @@ void buffer_check_dirty_writeback(struct page *page,
void mark_buffer_dirty(struct buffer_head *bh);
void mark_buffer_write_io_error(struct buffer_head *bh);
-void init_buffer(struct buffer_head *, bh_end_io_t *, void *);
void touch_buffer(struct buffer_head *bh);
void set_bh_page(struct buffer_head *bh,
struct page *page, unsigned long offset);