1 files changed, 373 insertions, 0 deletions
diff --git a/include/linux/iomap.h b/include/linux/iomap.h
new file mode 100644
index 000000000..238a03087
--- /dev/null
+++ b/include/linux/iomap.h
@@ -0,0 +1,373 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+#ifndef LINUX_IOMAP_H
+#define LINUX_IOMAP_H 1
+
+#include <linux/atomic.h>
+#include <linux/bitmap.h>
+#include <linux/blk_types.h>
+#include <linux/mm.h>
+#include <linux/types.h>
+#include <linux/mm_types.h>
+#include <linux/blkdev.h>
+
+struct address_space;
+struct fiemap_extent_info;
+struct inode;
+struct iomap_dio;
+struct iomap_writepage_ctx;
+struct iov_iter;
+struct kiocb;
+struct page;
+struct vm_area_struct;
+struct vm_fault;
+
+/*
+ * Types of block ranges for iomap mappings:
+ */
+#define IOMAP_HOLE	0	/* no blocks allocated, need allocation */
+#define IOMAP_DELALLOC	1	/* delayed allocation blocks */
+#define IOMAP_MAPPED	2	/* blocks allocated at @addr */
+#define IOMAP_UNWRITTEN	3	/* blocks allocated at @addr in unwritten state */
+#define IOMAP_INLINE	4	/* data inline in the inode */
+
+/*
+ * Flags reported by the file system from iomap_begin:
+ *
+ * IOMAP_F_NEW indicates that the blocks have been newly allocated and need
+ * zeroing for areas that no data is copied to.
+ *
+ * IOMAP_F_DIRTY indicates the inode has uncommitted metadata needed to access
+ * written data and requires fdatasync to commit them to persistent storage.
+ * This needs to take into account metadata changes that *may* be made at IO
+ * completion, such as file size updates from direct IO.
+ *
+ * IOMAP_F_SHARED indicates that the blocks are shared, and will need to be
+ * unshared as part a write.
+ *
+ * IOMAP_F_MERGED indicates that the iomap contains the merge of multiple block
+ * mappings.
+ *
+ * IOMAP_F_BUFFER_HEAD indicates that the file system requires the use of
+ * buffer heads for this mapping.
+ */
+#define IOMAP_F_NEW		0x01
+#define IOMAP_F_DIRTY		0x02
+#define IOMAP_F_SHARED		0x04
+#define IOMAP_F_MERGED		0x08
+#define IOMAP_F_BUFFER_HEAD	0x10
+#define IOMAP_F_ZONE_APPEND	0x20
+
+/*
+ * Flags set by the core iomap code during operations:
+ *
+ * IOMAP_F_SIZE_CHANGED indicates to the iomap_end method that the file size
+ * has changed as the result of this write operation.
+ */
+#define IOMAP_F_SIZE_CHANGED	0x100
+
+/*
+ * Flags from 0x1000 up are for file system specific usage:
+ */
+#define IOMAP_F_PRIVATE		0x1000
+
+
+/*
+ * Magic value for addr:
+ */
+#define IOMAP_NULL_ADDR -1ULL	/* addr is not valid */
+
+struct iomap_page_ops;
+
+struct iomap {
+	u64			addr; /* disk offset of mapping, bytes */
+	loff_t			offset;	/* file offset of mapping, bytes */
+	u64			length;	/* length of mapping, bytes */
+	u16			type;	/* type of mapping */
+	u16			flags;	/* flags for mapping */
+	struct block_device	*bdev;	/* block device for I/O */
+	struct dax_device	*dax_dev; /* dax_dev for dax operations */
+	void			*inline_data;
+	void			*private; /* filesystem private */
+	const struct iomap_page_ops *page_ops;
+};
+
+static inline sector_t iomap_sector(const struct iomap *iomap, loff_t pos)
+{
+	return (iomap->addr + pos - iomap->offset) >> SECTOR_SHIFT;
+}
+
+/*
+ * Returns the inline data pointer for logical offset @pos.
+ */
+static inline void *iomap_inline_data(const struct iomap *iomap, loff_t pos)
+{
+	return iomap->inline_data + pos - iomap->offset;
+}
+
+/*
+ * Check if the mapping's length is within the valid range for inline data.
+ * This is used to guard against accessing data beyond the page inline_data
+ * points at.
+ */
+static inline bool iomap_inline_data_valid(const struct iomap *iomap)
+{
+	return iomap->length <= PAGE_SIZE - offset_in_page(iomap->inline_data);
+}
+
+/*
+ * When a filesystem sets page_ops in an iomap mapping it returns, page_prepare
+ * and page_done will be called for each page written to.  This only applies to
+ * buffered writes as unbuffered writes will not typically have pages
+ * associated with them.
+ *
+ * When page_prepare succeeds, page_done will always be called to do any
+ * cleanup work necessary.  In that page_done call, @page will be NULL if the
+ * associated page could not be obtained.
+ */
+struct iomap_page_ops {
+	int (*page_prepare)(struct inode *inode, loff_t pos, unsigned len);
+	void (*page_done)(struct inode *inode, loff_t pos, unsigned copied,
+			struct page *page);
+};
+
+/*
+ * Flags for iomap_begin / iomap_end.  No flag implies a read.
+ */
+#define IOMAP_WRITE		(1 << 0) /* writing, must allocate blocks */
+#define IOMAP_ZERO		(1 << 1) /* zeroing operation, may skip holes */
+#define IOMAP_REPORT		(1 << 2) /* report extent status, e.g. FIEMAP */
+#define IOMAP_FAULT		(1 << 3) /* mapping for page fault */
+#define IOMAP_DIRECT		(1 << 4) /* direct I/O */
+#define IOMAP_NOWAIT		(1 << 5) /* do not block */
+#define IOMAP_OVERWRITE_ONLY	(1 << 6) /* only pure overwrites allowed */
+#define IOMAP_UNSHARE		(1 << 7) /* unshare_file_range */
+#ifdef CONFIG_FS_DAX
+#define IOMAP_DAX		(1 << 8) /* DAX mapping */
+#else
+#define IOMAP_DAX		0
+#endif /* CONFIG_FS_DAX */
+
+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,
+			struct iomap *srcmap);
+
+	/*
+	 * 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);
+};
+
+/**
+ * struct iomap_iter - Iterate through a range of a file
+ * @inode: Set at the start of the iteration and should not change.
+ * @pos: The current file position we are operating on.  It is updated by
+ *	calls to iomap_iter().  Treat as read-only in the body.
+ * @len: The remaining length of the file segment we're operating on.
+ *	It is updated at the same time as @pos.
+ * @processed: The number of bytes processed by the body in the most recent
+ *	iteration, or a negative errno. 0 causes the iteration to stop.
+ * @flags: Zero or more of the iomap_begin flags above.
+ * @iomap: Map describing the I/O iteration
+ * @srcmap: Source map for COW operations
+ */
+struct iomap_iter {
+	struct inode *inode;
+	loff_t pos;
+	u64 len;
+	s64 processed;
+	unsigned flags;
+	struct iomap iomap;
+	struct iomap srcmap;
+	void *private;
+};
+
+int iomap_iter(struct iomap_iter *iter, const struct iomap_ops *ops);
+
+/**
+ * iomap_length - length of the current iomap iteration
+ * @iter: iteration structure
+ *
+ * Returns the length that the operation applies to for the current iteration.
+ */
+static inline u64 iomap_length(const struct iomap_iter *iter)
+{
+	u64 end = iter->iomap.offset + iter->iomap.length;
+
+	if (iter->srcmap.type != IOMAP_HOLE)
+		end = min(end, iter->srcmap.offset + iter->srcmap.length);
+	return min(iter->len, end - iter->pos);
+}
+
+/**
+ * iomap_iter_srcmap - return the source map for the current iomap iteration
+ * @i: iteration structure
+ *
+ * Write operations on file systems with reflink support might require a
+ * source and a destination map.  This function retourns the source map
+ * for a given operation, which may or may no be identical to the destination
+ * map in &i->iomap.
+ */
+static inline const struct iomap *iomap_iter_srcmap(const struct iomap_iter *i)
+{
+	if (i->srcmap.type != IOMAP_HOLE)
+		return &i->srcmap;
+	return &i->iomap;
+}
+
+ssize_t iomap_file_buffered_write(struct kiocb *iocb, struct iov_iter *from,
+		const struct iomap_ops *ops);
+int iomap_read_folio(struct folio *folio, const struct iomap_ops *ops);
+void iomap_readahead(struct readahead_control *, const struct iomap_ops *ops);
+bool iomap_is_partially_uptodate(struct folio *, size_t from, size_t count);
+bool iomap_release_folio(struct folio *folio, gfp_t gfp_flags);
+void iomap_invalidate_folio(struct folio *folio, size_t offset, size_t len);
+int iomap_file_unshare(struct inode *inode, loff_t pos, loff_t len,
+		const struct iomap_ops *ops);
+int iomap_zero_range(struct inode *inode, loff_t pos, loff_t len,
+		bool *did_zero, const struct iomap_ops *ops);
+int iomap_truncate_page(struct inode *inode, loff_t pos, bool *did_zero,
+		const struct iomap_ops *ops);
+vm_fault_t iomap_page_mkwrite(struct vm_fault *vmf,
+			const struct iomap_ops *ops);
+int iomap_fiemap(struct inode *inode, struct fiemap_extent_info *fieinfo,
+		u64 start, u64 len, const struct iomap_ops *ops);
+loff_t iomap_seek_hole(struct inode *inode, loff_t offset,
+		const struct iomap_ops *ops);
+loff_t iomap_seek_data(struct inode *inode, loff_t offset,
+		const struct iomap_ops *ops);
+sector_t iomap_bmap(struct address_space *mapping, sector_t bno,
+		const struct iomap_ops *ops);
+
+/*
+ * Structure for writeback I/O completions.
+ */
+struct iomap_ioend {
+	struct list_head	io_list;	/* next ioend in chain */
+	u16			io_type;
+	u16			io_flags;	/* IOMAP_F_* */
+	u32			io_folios;	/* folios added to ioend */
+	struct inode		*io_inode;	/* file being written to */
+	size_t			io_size;	/* size of the extent */
+	loff_t			io_offset;	/* offset in the file */
+	sector_t		io_sector;	/* start sector of ioend */
+	struct bio		*io_bio;	/* bio being built */
+	struct bio		io_inline_bio;	/* MUST BE LAST! */
+};
+
+struct iomap_writeback_ops {
+	/*
+	 * Required, maps the blocks so that writeback can be performed on
+	 * the range starting at offset.
+	 */
+	int (*map_blocks)(struct iomap_writepage_ctx *wpc, struct inode *inode,
+				loff_t offset);
+
+	/*
+	 * Optional, allows the file systems to perform actions just before
+	 * submitting the bio and/or override the bio end_io handler for complex
+	 * operations like copy on write extent manipulation or unwritten extent
+	 * conversions.
+	 */
+	int (*prepare_ioend)(struct iomap_ioend *ioend, int status);
+
+	/*
+	 * Optional, allows the file system to discard state on a page where
+	 * we failed to submit any I/O.
+	 */
+	void (*discard_folio)(struct folio *folio, loff_t pos);
+};
+
+struct iomap_writepage_ctx {
+	struct iomap		iomap;
+	struct iomap_ioend	*ioend;
+	const struct iomap_writeback_ops *ops;
+};
+
+void iomap_finish_ioends(struct iomap_ioend *ioend, int error);
+void iomap_ioend_try_merge(struct iomap_ioend *ioend,
+		struct list_head *more_ioends);
+void iomap_sort_ioends(struct list_head *ioend_list);
+int iomap_writepages(struct address_space *mapping,
+		struct writeback_control *wbc, struct iomap_writepage_ctx *wpc,
+		const struct iomap_writeback_ops *ops);
+
+/*
+ * Flags for direct I/O ->end_io:
+ */
+#define IOMAP_DIO_UNWRITTEN	(1 << 0)	/* covers unwritten extent(s) */
+#define IOMAP_DIO_COW		(1 << 1)	/* covers COW extent(s) */
+
+struct iomap_dio_ops {
+	int (*end_io)(struct kiocb *iocb, ssize_t size, int error,
+		      unsigned flags);
+	void (*submit_io)(const struct iomap_iter *iter, struct bio *bio,
+		          loff_t file_offset);
+
+	/*
+	 * Filesystems wishing to attach private information to a direct io bio
+	 * must provide a ->submit_io method that attaches the additional
+	 * information to the bio and changes the ->bi_end_io callback to a
+	 * custom function.  This function should, at a minimum, perform any
+	 * relevant post-processing of the bio and end with a call to
+	 * iomap_dio_bio_end_io.
+	 */
+	struct bio_set *bio_set;
+};
+
+/*
+ * Wait for the I/O to complete in iomap_dio_rw even if the kiocb is not
+ * synchronous.
+ */
+#define IOMAP_DIO_FORCE_WAIT	(1 << 0)
+
+/*
+ * Do not allocate blocks or zero partial blocks, but instead fall back to
+ * the caller by returning -EAGAIN.  Used to optimize direct I/O writes that
+ * are not aligned to the file system block size.
+  */
+#define IOMAP_DIO_OVERWRITE_ONLY	(1 << 1)
+
+/*
+ * When a page fault occurs, return a partial synchronous result and allow
+ * the caller to retry the rest of the operation after dealing with the page
+ * fault.
+ */
+#define IOMAP_DIO_PARTIAL		(1 << 2)
+
+/*
+ * The caller will sync the write if needed; do not sync it within
+ * iomap_dio_rw.  Overrides IOMAP_DIO_FORCE_WAIT.
+ */
+#define IOMAP_DIO_NOSYNC		(1 << 3)
+
+ssize_t iomap_dio_rw(struct kiocb *iocb, struct iov_iter *iter,
+		const struct iomap_ops *ops, const struct iomap_dio_ops *dops,
+		unsigned int dio_flags, void *private, size_t done_before);
+struct iomap_dio *__iomap_dio_rw(struct kiocb *iocb, struct iov_iter *iter,
+		const struct iomap_ops *ops, const struct iomap_dio_ops *dops,
+		unsigned int dio_flags, void *private, size_t done_before);
+ssize_t iomap_dio_complete(struct iomap_dio *dio);
+void iomap_dio_bio_end_io(struct bio *bio);
+
+#ifdef CONFIG_SWAP
+struct file;
+struct swap_info_struct;
+
+int iomap_swapfile_activate(struct swap_info_struct *sis,
+		struct file *swap_file, sector_t *pagespan,
+		const struct iomap_ops *ops);
+#else
+# define iomap_swapfile_activate(sis, swapfile, pagespan, ops)	(-EIO)
+#endif /* CONFIG_SWAP */
+
+#endif /* LINUX_IOMAP_H */