X-Git-Url: http://git.onelab.eu/?a=blobdiff_plain;f=include%2Flinux%2Fbacking-dev.h;h=f7a1390d67f5b39da938c6be93c80cf0cd66fcf2;hb=f7f1b0f1e2fbadeab12d24236000e778aa9b1ead;hp=00371734995c9d01e4a7cb02abbb47ae5c53cb95;hpb=5273a3df6485dc2ad6aa7ddd441b9a21970f003b;p=linux-2.6.git

diff --git a/include/linux/backing-dev.h b/include/linux/backing-dev.h
index 003717349..f7a1390d6 100644
--- a/include/linux/backing-dev.h
+++ b/include/linux/backing-dev.h
@@ -25,15 +25,41 @@ typedef int (congested_fn)(void *, int);
 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);
@@ -62,4 +88,17 @@ static inline int bdi_rw_congested(struct backing_dev_info *bdi)
 				  (1 << BDI_write_congested));
 }
 
+#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 */