#include <asm/atomic.h>
+struct page;
+
/*
* Bits in backing_dev_info.state
*/
struct backing_dev_info {
unsigned long ra_pages; /* max readahead in PAGE_CACHE_SIZE units */
unsigned long state; /* Always use atomic bitops on this */
- int memory_backed; /* Cannot clean pages with writepage */
+ unsigned int capabilities; /* Device capabilities */
congested_fn *congested_fn; /* Function pointer if device is md/dm */
void *congested_data; /* Pointer to aux data for congested func */
- void (*unplug_io_fn)(struct backing_dev_info *);
+ void (*unplug_io_fn)(struct backing_dev_info *, struct page *);
void *unplug_io_data;
};
+
+/*
+ * 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
+ */
+#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_VMFLAGS \
+ (BDI_CAP_READ_MAP | BDI_CAP_WRITE_MAP | BDI_CAP_EXEC_MAP)
+
+#if defined(VM_MAYREAD) && \
+ (BDI_CAP_READ_MAP != VM_MAYREAD || \
+ BDI_CAP_WRITE_MAP != VM_MAYWRITE || \
+ BDI_CAP_EXEC_MAP != VM_MAYEXEC)
+#error please change backing_dev_info::capabilities flags
+#endif
+
extern struct backing_dev_info default_backing_dev_info;
-void default_unplug_io_fn(struct backing_dev_info *bdi);
+void default_unplug_io_fn(struct backing_dev_info *bdi, struct page *page);
int writeback_acquire(struct backing_dev_info *bdi);
int writeback_in_progress(struct backing_dev_info *bdi);
(1 << BDI_write_congested));
}
+void clear_bdi_congested(struct backing_dev_info *bdi, int rw);
+void set_bdi_congested(struct backing_dev_info *bdi, int rw);
+long congestion_wait(int rw, long timeout);
+void congestion_end(int rw);
+
+#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))
+
+#define mapping_cap_writeback_dirty(mapping) \
+ bdi_cap_writeback_dirty((mapping)->backing_dev_info)
+
+#define mapping_cap_account_dirty(mapping) \
+ bdi_cap_account_dirty((mapping)->backing_dev_info)
+
+
#endif /* _LINUX_BACKING_DEV_H */