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/* SPDX-License-Identifier: GPL-2.0 */
#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 */
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;
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_readpage(struct page *page, const struct iomap_ops *ops);
void iomap_readahead(struct readahead_control *, const struct iomap_ops *ops);
int iomap_is_partially_uptodate(struct page *page, unsigned long from,
unsigned long count);
int iomap_releasepage(struct page *page, gfp_t gfp_mask);
void iomap_invalidatepage(struct page *page, unsigned int offset,
unsigned int len);
int iomap_migrate_page(struct address_space *mapping, struct page *newpage,
struct page *page, enum migrate_mode mode);
#define iomap_migrate_page NULL
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_* */
struct inode *io_inode; /* file being written to */
size_t io_size; /* size of the extent */
loff_t io_offset; /* offset in the file */
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_page)(struct page *page, loff_t fileoff);
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_writepage(struct page *page, struct writeback_control *wbc,
struct iomap_writepage_ctx *wpc,
const struct iomap_writeback_ops *ops);
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);
* 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.
* 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)
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, 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, size_t done_before);
ssize_t iomap_dio_complete(struct iomap_dio *dio);
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);
# define iomap_swapfile_activate(sis, swapfile, pagespan, ops) (-EIO)
#endif /* CONFIG_SWAP */
#endif /* LINUX_IOMAP_H */