fs: introduce f_op->mmap_capabilities for nommu mmap support
Since "BDI: Provide backing device capability information [try #3]" the
backing_dev_info structure also provides flags for the kind of mmap
operation available in a nommu environment, which is entirely unrelated
to it's original purpose.
Introduce a new nommu-only file operation to provide this information to
the nommu mmap code instead. Splitting this from the backing_dev_info
structure allows to remove lots of backing_dev_info instance that aren't
otherwise needed, and entirely gets rid of the concept of providing a
backing_dev_info for a character device. It also removes the need for
the mtd_inodefs filesystem.
Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Tejun Heo <tj@kernel.org>
Acked-by: Brian Norris <computersforpeace@gmail.com>
Signed-off-by: Jens Axboe <axboe@fb.com>
diff --git a/include/linux/backing-dev.h b/include/linux/backing-dev.h
index e936cea..478f95d 100644
--- a/include/linux/backing-dev.h
+++ b/include/linux/backing-dev.h
@@ -114,7 +114,7 @@
const char *fmt, ...);
int bdi_register_dev(struct backing_dev_info *bdi, dev_t dev);
void bdi_unregister(struct backing_dev_info *bdi);
-int __must_check bdi_setup_and_register(struct backing_dev_info *, char *, unsigned int);
+int __must_check bdi_setup_and_register(struct backing_dev_info *, char *);
void bdi_start_writeback(struct backing_dev_info *bdi, long nr_pages,
enum wb_reason reason);
void bdi_start_background_writeback(struct backing_dev_info *bdi);
@@ -228,42 +228,17 @@
* 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
- *
* BDI_CAP_STRICTLIMIT: Keep number of dirty pages below bdi threshold.
*/
#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_STABLE_WRITES 0x00000200
-#define BDI_CAP_STRICTLIMIT 0x00000400
-
-#define BDI_CAP_VMFLAGS \
- (BDI_CAP_READ_MAP | BDI_CAP_WRITE_MAP | BDI_CAP_EXEC_MAP)
+#define BDI_CAP_NO_ACCT_WB 0x00000004
+#define BDI_CAP_STABLE_WRITES 0x00000008
+#define BDI_CAP_STRICTLIMIT 0x00000010
#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 || \
- BDI_CAP_EXEC_MAP != VM_MAYEXEC)
-#error please change backing_dev_info::capabilities flags
-#endif
-
extern struct backing_dev_info default_backing_dev_info;
extern struct backing_dev_info noop_backing_dev_info;
diff --git a/include/linux/cdev.h b/include/linux/cdev.h
index fb45919..f876361 100644
--- a/include/linux/cdev.h
+++ b/include/linux/cdev.h
@@ -30,6 +30,4 @@
void cd_forget(struct inode *);
-extern struct backing_dev_info directly_mappable_cdev_bdi;
-
#endif
diff --git a/include/linux/fs.h b/include/linux/fs.h
index 42efe13..1dada39 100644
--- a/include/linux/fs.h
+++ b/include/linux/fs.h
@@ -1502,6 +1502,26 @@
#define HAVE_COMPAT_IOCTL 1
#define HAVE_UNLOCKED_IOCTL 1
+/*
+ * These flags let !MMU mmap() govern direct device mapping vs immediate
+ * copying more easily for MAP_PRIVATE, especially for ROM filesystems.
+ *
+ * NOMMU_MAP_COPY: Copy can be mapped (MAP_PRIVATE)
+ * NOMMU_MAP_DIRECT: Can be mapped directly (MAP_SHARED)
+ * NOMMU_MAP_READ: Can be mapped for reading
+ * NOMMU_MAP_WRITE: Can be mapped for writing
+ * NOMMU_MAP_EXEC: Can be mapped for execution
+ */
+#define NOMMU_MAP_COPY 0x00000001
+#define NOMMU_MAP_DIRECT 0x00000008
+#define NOMMU_MAP_READ VM_MAYREAD
+#define NOMMU_MAP_WRITE VM_MAYWRITE
+#define NOMMU_MAP_EXEC VM_MAYEXEC
+
+#define NOMMU_VMFLAGS \
+ (NOMMU_MAP_READ | NOMMU_MAP_WRITE | NOMMU_MAP_EXEC)
+
+
struct iov_iter;
struct file_operations {
@@ -1536,6 +1556,9 @@
long (*fallocate)(struct file *file, int mode, loff_t offset,
loff_t len);
void (*show_fdinfo)(struct seq_file *m, struct file *f);
+#ifndef CONFIG_MMU
+ unsigned (*mmap_capabilities)(struct file *);
+#endif
};
struct inode_operations {
diff --git a/include/linux/mtd/mtd.h b/include/linux/mtd/mtd.h
index 031ff3a..3301c4c 100644
--- a/include/linux/mtd/mtd.h
+++ b/include/linux/mtd/mtd.h
@@ -408,4 +408,6 @@
return mtd_is_bitflip(err) || mtd_is_eccerr(err);
}
+unsigned mtd_mmap_capabilities(struct mtd_info *mtd);
+
#endif /* __MTD_MTD_H__ */