1 /* SPDX-License-Identifier: GPL-2.0 */
2 #ifndef LINUX_IOMAP_H
3 #define LINUX_IOMAP_H 1
4 
5 #include <linux/atomic.h>
6 #include <linux/bitmap.h>
7 #include <linux/blk_types.h>
8 #include <linux/mm.h>
9 #include <linux/types.h>
10 #include <linux/mm_types.h>
11 #include <linux/blkdev.h>
12 
13 struct address_space;
14 struct fiemap_extent_info;
15 struct inode;
16 struct iomap_dio;
17 struct iomap_writepage_ctx;
18 struct iov_iter;
19 struct kiocb;
20 struct page;
21 struct vm_area_struct;
22 struct vm_fault;
23 
24 /*
25  * Types of block ranges for iomap mappings:
26  */
27 #define IOMAP_HOLE	0	/* no blocks allocated, need allocation */
28 #define IOMAP_DELALLOC	1	/* delayed allocation blocks */
29 #define IOMAP_MAPPED	2	/* blocks allocated at @addr */
30 #define IOMAP_UNWRITTEN	3	/* blocks allocated at @addr in unwritten state */
31 #define IOMAP_INLINE	4	/* data inline in the inode */
32 
33 /*
34  * Flags reported by the file system from iomap_begin:
35  *
36  * IOMAP_F_NEW indicates that the blocks have been newly allocated and need
37  * zeroing for areas that no data is copied to.
38  *
39  * IOMAP_F_DIRTY indicates the inode has uncommitted metadata needed to access
40  * written data and requires fdatasync to commit them to persistent storage.
41  * This needs to take into account metadata changes that *may* be made at IO
42  * completion, such as file size updates from direct IO.
43  *
44  * IOMAP_F_SHARED indicates that the blocks are shared, and will need to be
45  * unshared as part a write.
46  *
47  * IOMAP_F_MERGED indicates that the iomap contains the merge of multiple block
48  * mappings.
49  *
50  * IOMAP_F_BUFFER_HEAD indicates that the file system requires the use of
51  * buffer heads for this mapping.
52  */
53 #define IOMAP_F_NEW		0x01
54 #define IOMAP_F_DIRTY		0x02
55 #define IOMAP_F_SHARED		0x04
56 #define IOMAP_F_MERGED		0x08
57 #define IOMAP_F_BUFFER_HEAD	0x10
58 #define IOMAP_F_ZONE_APPEND	0x20
59 
60 /*
61  * Flags set by the core iomap code during operations:
62  *
63  * IOMAP_F_SIZE_CHANGED indicates to the iomap_end method that the file size
64  * has changed as the result of this write operation.
65  */
66 #define IOMAP_F_SIZE_CHANGED	0x100
67 
68 /*
69  * Flags from 0x1000 up are for file system specific usage:
70  */
71 #define IOMAP_F_PRIVATE		0x1000
72 
73 
74 /*
75  * Magic value for addr:
76  */
77 #define IOMAP_NULL_ADDR -1ULL	/* addr is not valid */
78 
79 struct iomap_page_ops;
80 
81 struct iomap {
82 	u64			addr; /* disk offset of mapping, bytes */
83 	loff_t			offset;	/* file offset of mapping, bytes */
84 	u64			length;	/* length of mapping, bytes */
85 	u16			type;	/* type of mapping */
86 	u16			flags;	/* flags for mapping */
87 	struct block_device	*bdev;	/* block device for I/O */
88 	struct dax_device	*dax_dev; /* dax_dev for dax operations */
89 	void			*inline_data;
90 	void			*private; /* filesystem private */
91 	const struct iomap_page_ops *page_ops;
92 };
93 
iomap_sector(const struct iomap * iomap,loff_t pos)94 static inline sector_t iomap_sector(const struct iomap *iomap, loff_t pos)
95 {
96 	return (iomap->addr + pos - iomap->offset) >> SECTOR_SHIFT;
97 }
98 
99 /*
100  * Returns the inline data pointer for logical offset @pos.
101  */
iomap_inline_data(const struct iomap * iomap,loff_t pos)102 static inline void *iomap_inline_data(const struct iomap *iomap, loff_t pos)
103 {
104 	return iomap->inline_data + pos - iomap->offset;
105 }
106 
107 /*
108  * Check if the mapping's length is within the valid range for inline data.
109  * This is used to guard against accessing data beyond the page inline_data
110  * points at.
111  */
iomap_inline_data_valid(const struct iomap * iomap)112 static inline bool iomap_inline_data_valid(const struct iomap *iomap)
113 {
114 	return iomap->length <= PAGE_SIZE - offset_in_page(iomap->inline_data);
115 }
116 
117 /*
118  * When a filesystem sets page_ops in an iomap mapping it returns, page_prepare
119  * and page_done will be called for each page written to.  This only applies to
120  * buffered writes as unbuffered writes will not typically have pages
121  * associated with them.
122  *
123  * When page_prepare succeeds, page_done will always be called to do any
124  * cleanup work necessary.  In that page_done call, @page will be NULL if the
125  * associated page could not be obtained.
126  */
127 struct iomap_page_ops {
128 	int (*page_prepare)(struct inode *inode, loff_t pos, unsigned len);
129 	void (*page_done)(struct inode *inode, loff_t pos, unsigned copied,
130 			struct page *page);
131 };
132 
133 /*
134  * Flags for iomap_begin / iomap_end.  No flag implies a read.
135  */
136 #define IOMAP_WRITE		(1 << 0) /* writing, must allocate blocks */
137 #define IOMAP_ZERO		(1 << 1) /* zeroing operation, may skip holes */
138 #define IOMAP_REPORT		(1 << 2) /* report extent status, e.g. FIEMAP */
139 #define IOMAP_FAULT		(1 << 3) /* mapping for page fault */
140 #define IOMAP_DIRECT		(1 << 4) /* direct I/O */
141 #define IOMAP_NOWAIT		(1 << 5) /* do not block */
142 #define IOMAP_OVERWRITE_ONLY	(1 << 6) /* only pure overwrites allowed */
143 #define IOMAP_UNSHARE		(1 << 7) /* unshare_file_range */
144 #ifdef CONFIG_FS_DAX
145 #define IOMAP_DAX		(1 << 8) /* DAX mapping */
146 #else
147 #define IOMAP_DAX		0
148 #endif /* CONFIG_FS_DAX */
149 
150 struct iomap_ops {
151 	/*
152 	 * Return the existing mapping at pos, or reserve space starting at
153 	 * pos for up to length, as long as we can do it as a single mapping.
154 	 * The actual length is returned in iomap->length.
155 	 */
156 	int (*iomap_begin)(struct inode *inode, loff_t pos, loff_t length,
157 			unsigned flags, struct iomap *iomap,
158 			struct iomap *srcmap);
159 
160 	/*
161 	 * Commit and/or unreserve space previous allocated using iomap_begin.
162 	 * Written indicates the length of the successful write operation which
163 	 * needs to be commited, while the rest needs to be unreserved.
164 	 * Written might be zero if no data was written.
165 	 */
166 	int (*iomap_end)(struct inode *inode, loff_t pos, loff_t length,
167 			ssize_t written, unsigned flags, struct iomap *iomap);
168 };
169 
170 /**
171  * struct iomap_iter - Iterate through a range of a file
172  * @inode: Set at the start of the iteration and should not change.
173  * @pos: The current file position we are operating on.  It is updated by
174  *	calls to iomap_iter().  Treat as read-only in the body.
175  * @len: The remaining length of the file segment we're operating on.
176  *	It is updated at the same time as @pos.
177  * @processed: The number of bytes processed by the body in the most recent
178  *	iteration, or a negative errno. 0 causes the iteration to stop.
179  * @flags: Zero or more of the iomap_begin flags above.
180  * @iomap: Map describing the I/O iteration
181  * @srcmap: Source map for COW operations
182  */
183 struct iomap_iter {
184 	struct inode *inode;
185 	loff_t pos;
186 	u64 len;
187 	s64 processed;
188 	unsigned flags;
189 	struct iomap iomap;
190 	struct iomap srcmap;
191 	void *private;
192 };
193 
194 int iomap_iter(struct iomap_iter *iter, const struct iomap_ops *ops);
195 
196 /**
197  * iomap_length - length of the current iomap iteration
198  * @iter: iteration structure
199  *
200  * Returns the length that the operation applies to for the current iteration.
201  */
iomap_length(const struct iomap_iter * iter)202 static inline u64 iomap_length(const struct iomap_iter *iter)
203 {
204 	u64 end = iter->iomap.offset + iter->iomap.length;
205 
206 	if (iter->srcmap.type != IOMAP_HOLE)
207 		end = min(end, iter->srcmap.offset + iter->srcmap.length);
208 	return min(iter->len, end - iter->pos);
209 }
210 
211 /**
212  * iomap_iter_srcmap - return the source map for the current iomap iteration
213  * @i: iteration structure
214  *
215  * Write operations on file systems with reflink support might require a
216  * source and a destination map.  This function retourns the source map
217  * for a given operation, which may or may no be identical to the destination
218  * map in &i->iomap.
219  */
iomap_iter_srcmap(const struct iomap_iter * i)220 static inline const struct iomap *iomap_iter_srcmap(const struct iomap_iter *i)
221 {
222 	if (i->srcmap.type != IOMAP_HOLE)
223 		return &i->srcmap;
224 	return &i->iomap;
225 }
226 
227 ssize_t iomap_file_buffered_write(struct kiocb *iocb, struct iov_iter *from,
228 		const struct iomap_ops *ops);
229 int iomap_read_folio(struct folio *folio, const struct iomap_ops *ops);
230 void iomap_readahead(struct readahead_control *, const struct iomap_ops *ops);
231 bool iomap_is_partially_uptodate(struct folio *, size_t from, size_t count);
232 bool iomap_release_folio(struct folio *folio, gfp_t gfp_flags);
233 void iomap_invalidate_folio(struct folio *folio, size_t offset, size_t len);
234 int iomap_file_unshare(struct inode *inode, loff_t pos, loff_t len,
235 		const struct iomap_ops *ops);
236 int iomap_zero_range(struct inode *inode, loff_t pos, loff_t len,
237 		bool *did_zero, const struct iomap_ops *ops);
238 int iomap_truncate_page(struct inode *inode, loff_t pos, bool *did_zero,
239 		const struct iomap_ops *ops);
240 vm_fault_t iomap_page_mkwrite(struct vm_fault *vmf,
241 			const struct iomap_ops *ops);
242 int iomap_fiemap(struct inode *inode, struct fiemap_extent_info *fieinfo,
243 		u64 start, u64 len, const struct iomap_ops *ops);
244 loff_t iomap_seek_hole(struct inode *inode, loff_t offset,
245 		const struct iomap_ops *ops);
246 loff_t iomap_seek_data(struct inode *inode, loff_t offset,
247 		const struct iomap_ops *ops);
248 sector_t iomap_bmap(struct address_space *mapping, sector_t bno,
249 		const struct iomap_ops *ops);
250 
251 /*
252  * Structure for writeback I/O completions.
253  */
254 struct iomap_ioend {
255 	struct list_head	io_list;	/* next ioend in chain */
256 	u16			io_type;
257 	u16			io_flags;	/* IOMAP_F_* */
258 	u32			io_folios;	/* folios added to ioend */
259 	struct inode		*io_inode;	/* file being written to */
260 	size_t			io_size;	/* size of the extent */
261 	loff_t			io_offset;	/* offset in the file */
262 	sector_t		io_sector;	/* start sector of ioend */
263 	struct bio		*io_bio;	/* bio being built */
264 	struct bio		io_inline_bio;	/* MUST BE LAST! */
265 };
266 
267 struct iomap_writeback_ops {
268 	/*
269 	 * Required, maps the blocks so that writeback can be performed on
270 	 * the range starting at offset.
271 	 */
272 	int (*map_blocks)(struct iomap_writepage_ctx *wpc, struct inode *inode,
273 				loff_t offset);
274 
275 	/*
276 	 * Optional, allows the file systems to perform actions just before
277 	 * submitting the bio and/or override the bio end_io handler for complex
278 	 * operations like copy on write extent manipulation or unwritten extent
279 	 * conversions.
280 	 */
281 	int (*prepare_ioend)(struct iomap_ioend *ioend, int status);
282 
283 	/*
284 	 * Optional, allows the file system to discard state on a page where
285 	 * we failed to submit any I/O.
286 	 */
287 	void (*discard_folio)(struct folio *folio, loff_t pos);
288 };
289 
290 struct iomap_writepage_ctx {
291 	struct iomap		iomap;
292 	struct iomap_ioend	*ioend;
293 	const struct iomap_writeback_ops *ops;
294 };
295 
296 void iomap_finish_ioends(struct iomap_ioend *ioend, int error);
297 void iomap_ioend_try_merge(struct iomap_ioend *ioend,
298 		struct list_head *more_ioends);
299 void iomap_sort_ioends(struct list_head *ioend_list);
300 int iomap_writepages(struct address_space *mapping,
301 		struct writeback_control *wbc, struct iomap_writepage_ctx *wpc,
302 		const struct iomap_writeback_ops *ops);
303 
304 /*
305  * Flags for direct I/O ->end_io:
306  */
307 #define IOMAP_DIO_UNWRITTEN	(1 << 0)	/* covers unwritten extent(s) */
308 #define IOMAP_DIO_COW		(1 << 1)	/* covers COW extent(s) */
309 
310 struct iomap_dio_ops {
311 	int (*end_io)(struct kiocb *iocb, ssize_t size, int error,
312 		      unsigned flags);
313 	void (*submit_io)(const struct iomap_iter *iter, struct bio *bio,
314 		          loff_t file_offset);
315 
316 	/*
317 	 * Filesystems wishing to attach private information to a direct io bio
318 	 * must provide a ->submit_io method that attaches the additional
319 	 * information to the bio and changes the ->bi_end_io callback to a
320 	 * custom function.  This function should, at a minimum, perform any
321 	 * relevant post-processing of the bio and end with a call to
322 	 * iomap_dio_bio_end_io.
323 	 */
324 	struct bio_set *bio_set;
325 };
326 
327 /*
328  * Wait for the I/O to complete in iomap_dio_rw even if the kiocb is not
329  * synchronous.
330  */
331 #define IOMAP_DIO_FORCE_WAIT	(1 << 0)
332 
333 /*
334  * Do not allocate blocks or zero partial blocks, but instead fall back to
335  * the caller by returning -EAGAIN.  Used to optimize direct I/O writes that
336  * are not aligned to the file system block size.
337   */
338 #define IOMAP_DIO_OVERWRITE_ONLY	(1 << 1)
339 
340 /*
341  * When a page fault occurs, return a partial synchronous result and allow
342  * the caller to retry the rest of the operation after dealing with the page
343  * fault.
344  */
345 #define IOMAP_DIO_PARTIAL		(1 << 2)
346 
347 /*
348  * The caller will sync the write if needed; do not sync it within
349  * iomap_dio_rw.  Overrides IOMAP_DIO_FORCE_WAIT.
350  */
351 #define IOMAP_DIO_NOSYNC		(1 << 3)
352 
353 ssize_t iomap_dio_rw(struct kiocb *iocb, struct iov_iter *iter,
354 		const struct iomap_ops *ops, const struct iomap_dio_ops *dops,
355 		unsigned int dio_flags, void *private, size_t done_before);
356 struct iomap_dio *__iomap_dio_rw(struct kiocb *iocb, struct iov_iter *iter,
357 		const struct iomap_ops *ops, const struct iomap_dio_ops *dops,
358 		unsigned int dio_flags, void *private, size_t done_before);
359 ssize_t iomap_dio_complete(struct iomap_dio *dio);
360 void iomap_dio_bio_end_io(struct bio *bio);
361 
362 #ifdef CONFIG_SWAP
363 struct file;
364 struct swap_info_struct;
365 
366 int iomap_swapfile_activate(struct swap_info_struct *sis,
367 		struct file *swap_file, sector_t *pagespan,
368 		const struct iomap_ops *ops);
369 #else
370 # define iomap_swapfile_activate(sis, swapfile, pagespan, ops)	(-EIO)
371 #endif /* CONFIG_SWAP */
372 
373 #endif /* LINUX_IOMAP_H */
374