fs: introduce iomap infrastructure

[mirror_ubuntu-zesty-kernel.git] / include / linux / iomap.h

diff --git a/include/linux/iomap.h b/include/linux/iomap.h
index 1b22197bcf0116e0eebb0f899a023f2ff84e4392..d2f469ae899af4e83b422ab778c8d6f87b524466 100644 (file)
--- a/include/linux/iomap.h
+++ b/include/linux/iomap.h
@@ -3,19 +3,65 @@
 
 #include <linux/types.h>
 
-/* types of block ranges for multipage write mappings. */
+struct inode;
+struct iov_iter;
+struct kiocb;
+struct vm_area_struct;
+struct vm_fault;
+
+/*
+ * Types of block ranges for iomap mappings:
+ */
 #define IOMAP_HOLE     0x01    /* no blocks allocated, need allocation */
 #define IOMAP_DELALLOC 0x02    /* delayed allocation blocks */
 #define IOMAP_MAPPED   0x03    /* blocks allocated @blkno */
 #define IOMAP_UNWRITTEN        0x04    /* blocks allocated @blkno in unwritten state */
 
+/*
+ * Magic value for blkno:
+ */
 #define IOMAP_NULL_BLOCK -1LL  /* blkno is not valid */
 
 struct iomap {
-       sector_t        blkno;  /* first sector of mapping */
-       loff_t          offset; /* file offset of mapping, bytes */
-       u64             length; /* length of mapping, bytes */
-       int             type;   /* type of mapping */
+       sector_t                blkno;  /* 1st sector of mapping, 512b units */
+       loff_t                  offset; /* file offset of mapping, bytes */
+       u64                     length; /* length of mapping, bytes */
+       int                     type;   /* type of mapping */
+       struct block_device     *bdev;  /* block device for I/O */
+};
+
+/*
+ * Flags for iomap_begin / iomap_end.  No flag implies a read.
+ */
+#define IOMAP_WRITE            (1 << 0)
+#define IOMAP_ZERO             (1 << 1)
+
+struct iomap_ops {
+       /*
+        * Return the existing mapping at pos, or reserve space starting at
+        * pos for up to length, as long as we can do it as a single mapping.
+        * The actual length is returned in iomap->length.
+        */
+       int (*iomap_begin)(struct inode *inode, loff_t pos, loff_t length,
+                       unsigned flags, struct iomap *iomap);
+
+       /*
+        * Commit and/or unreserve space previous allocated using iomap_begin.
+        * Written indicates the length of the successful write operation which
+        * needs to be commited, while the rest needs to be unreserved.
+        * Written might be zero if no data was written.
+        */
+       int (*iomap_end)(struct inode *inode, loff_t pos, loff_t length,
+                       ssize_t written, unsigned flags, struct iomap *iomap);
 };
 
+ssize_t iomap_file_buffered_write(struct kiocb *iocb, struct iov_iter *from,
+               struct iomap_ops *ops);
+int iomap_zero_range(struct inode *inode, loff_t pos, loff_t len,
+               bool *did_zero, struct iomap_ops *ops);
+int iomap_truncate_page(struct inode *inode, loff_t pos, bool *did_zero,
+               struct iomap_ops *ops);
+int iomap_page_mkwrite(struct vm_area_struct *vma, struct vm_fault *vmf,
+               struct iomap_ops *ops);
+
 #endif /* LINUX_IOMAP_H */