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 /* 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 */

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