mm: bdi: add separate writeback accounting capability
Add a new BDI capability flag: BDI_CAP_NO_ACCT_WB. If this flag is
set, then don't update the per-bdi writeback stats from
test_set_page_writeback() and test_clear_page_writeback().
Misc cleanups:
- convert bdi_cap_writeback_dirty() and friends to static inline functions
- create a flag that includes all three dirty/writeback related flags,
since almst all users will want to have them toghether
Signed-off-by: Miklos Szeredi <mszeredi@suse.cz>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
diff --git a/include/linux/backing-dev.h b/include/linux/backing-dev.h
index c49a2d0..13ab79d 100644
--- a/include/linux/backing-dev.h
+++ b/include/linux/backing-dev.h
@@ -12,6 +12,7 @@
#include <linux/log2.h>
#include <linux/proportions.h>
#include <linux/kernel.h>
+#include <linux/fs.h>
#include <asm/atomic.h>
struct page;
@@ -151,22 +152,43 @@
/*
* Flags in backing_dev_info::capability
- * - The first two flags control whether dirty pages will contribute to the
- * VM's accounting and whether writepages() should be called for dirty pages
- * (something that would not, for example, be appropriate for ramfs)
- * - These flags let !MMU mmap() govern direct device mapping vs immediate
- * copying more easily for MAP_PRIVATE, especially for ROM filesystems
+ *
+ * The first three flags control whether dirty pages will contribute to the
+ * VM's accounting and whether writepages() should be called for dirty pages
+ * (something that would not, for example, be appropriate for ramfs)
+ *
+ * WARNING: these flags are closely related and should not normally be
+ * used separately. The BDI_CAP_NO_ACCT_AND_WRITEBACK combines these
+ * three flags into a single convenience macro.
+ *
+ * BDI_CAP_NO_ACCT_DIRTY: Dirty pages shouldn't contribute to accounting
+ * BDI_CAP_NO_WRITEBACK: Don't write pages back
+ * BDI_CAP_NO_ACCT_WB: Don't automatically account writeback pages
+ *
+ * These flags let !MMU mmap() govern direct device mapping vs immediate
+ * copying more easily for MAP_PRIVATE, especially for ROM filesystems.
+ *
+ * BDI_CAP_MAP_COPY: Copy can be mapped (MAP_PRIVATE)
+ * BDI_CAP_MAP_DIRECT: Can be mapped directly (MAP_SHARED)
+ * BDI_CAP_READ_MAP: Can be mapped for reading
+ * BDI_CAP_WRITE_MAP: Can be mapped for writing
+ * BDI_CAP_EXEC_MAP: Can be mapped for execution
*/
-#define BDI_CAP_NO_ACCT_DIRTY 0x00000001 /* Dirty pages shouldn't contribute to accounting */
-#define BDI_CAP_NO_WRITEBACK 0x00000002 /* Don't write pages back */
-#define BDI_CAP_MAP_COPY 0x00000004 /* Copy can be mapped (MAP_PRIVATE) */
-#define BDI_CAP_MAP_DIRECT 0x00000008 /* Can be mapped directly (MAP_SHARED) */
-#define BDI_CAP_READ_MAP 0x00000010 /* Can be mapped for reading */
-#define BDI_CAP_WRITE_MAP 0x00000020 /* Can be mapped for writing */
-#define BDI_CAP_EXEC_MAP 0x00000040 /* Can be mapped for execution */
+#define BDI_CAP_NO_ACCT_DIRTY 0x00000001
+#define BDI_CAP_NO_WRITEBACK 0x00000002
+#define BDI_CAP_MAP_COPY 0x00000004
+#define BDI_CAP_MAP_DIRECT 0x00000008
+#define BDI_CAP_READ_MAP 0x00000010
+#define BDI_CAP_WRITE_MAP 0x00000020
+#define BDI_CAP_EXEC_MAP 0x00000040
+#define BDI_CAP_NO_ACCT_WB 0x00000080
+
#define BDI_CAP_VMFLAGS \
(BDI_CAP_READ_MAP | BDI_CAP_WRITE_MAP | BDI_CAP_EXEC_MAP)
+#define BDI_CAP_NO_ACCT_AND_WRITEBACK \
+ (BDI_CAP_NO_WRITEBACK | BDI_CAP_NO_ACCT_DIRTY | BDI_CAP_NO_ACCT_WB)
+
#if defined(VM_MAYREAD) && \
(BDI_CAP_READ_MAP != VM_MAYREAD || \
BDI_CAP_WRITE_MAP != VM_MAYWRITE || \
@@ -206,17 +228,32 @@
void set_bdi_congested(struct backing_dev_info *bdi, int rw);
long congestion_wait(int rw, long timeout);
-#define bdi_cap_writeback_dirty(bdi) \
- (!((bdi)->capabilities & BDI_CAP_NO_WRITEBACK))
-#define bdi_cap_account_dirty(bdi) \
- (!((bdi)->capabilities & BDI_CAP_NO_ACCT_DIRTY))
+static inline bool bdi_cap_writeback_dirty(struct backing_dev_info *bdi)
+{
+ return !(bdi->capabilities & BDI_CAP_NO_WRITEBACK);
+}
-#define mapping_cap_writeback_dirty(mapping) \
- bdi_cap_writeback_dirty((mapping)->backing_dev_info)
+static inline bool bdi_cap_account_dirty(struct backing_dev_info *bdi)
+{
+ return !(bdi->capabilities & BDI_CAP_NO_ACCT_DIRTY);
+}
-#define mapping_cap_account_dirty(mapping) \
- bdi_cap_account_dirty((mapping)->backing_dev_info)
+static inline bool bdi_cap_account_writeback(struct backing_dev_info *bdi)
+{
+ /* Paranoia: BDI_CAP_NO_WRITEBACK implies BDI_CAP_NO_ACCT_WB */
+ return !(bdi->capabilities & (BDI_CAP_NO_ACCT_WB |
+ BDI_CAP_NO_WRITEBACK));
+}
+static inline bool mapping_cap_writeback_dirty(struct address_space *mapping)
+{
+ return bdi_cap_writeback_dirty(mapping->backing_dev_info);
+}
+
+static inline bool mapping_cap_account_dirty(struct address_space *mapping)
+{
+ return bdi_cap_account_dirty(mapping->backing_dev_info);
+}
#endif /* _LINUX_BACKING_DEV_H */