xref: /openbmc/linux/fs/omfs/file.c (revision 5aaa4024)
1 // SPDX-License-Identifier: GPL-2.0-only
2 /*
3  * OMFS (as used by RIO Karma) file operations.
4  * Copyright (C) 2005 Bob Copeland <me@bobcopeland.com>
5  */
6 
7 #include <linux/module.h>
8 #include <linux/fs.h>
9 #include <linux/buffer_head.h>
10 #include <linux/mpage.h>
11 #include "omfs.h"
12 
13 static u32 omfs_max_extents(struct omfs_sb_info *sbi, int offset)
14 {
15 	return (sbi->s_sys_blocksize - offset -
16 		sizeof(struct omfs_extent)) /
17 		sizeof(struct omfs_extent_entry) + 1;
18 }
19 
20 void omfs_make_empty_table(struct buffer_head *bh, int offset)
21 {
22 	struct omfs_extent *oe = (struct omfs_extent *) &bh->b_data[offset];
23 
24 	oe->e_next = ~cpu_to_be64(0ULL);
25 	oe->e_extent_count = cpu_to_be32(1),
26 	oe->e_fill = cpu_to_be32(0x22),
27 	oe->e_entry.e_cluster = ~cpu_to_be64(0ULL);
28 	oe->e_entry.e_blocks = ~cpu_to_be64(0ULL);
29 }
30 
31 int omfs_shrink_inode(struct inode *inode)
32 {
33 	struct omfs_sb_info *sbi = OMFS_SB(inode->i_sb);
34 	struct omfs_extent *oe;
35 	struct omfs_extent_entry *entry;
36 	struct buffer_head *bh;
37 	u64 next, last;
38 	u32 extent_count;
39 	u32 max_extents;
40 	int ret;
41 
42 	/* traverse extent table, freeing each entry that is greater
43 	 * than inode->i_size;
44 	 */
45 	next = inode->i_ino;
46 
47 	/* only support truncate -> 0 for now */
48 	ret = -EIO;
49 	if (inode->i_size != 0)
50 		goto out;
51 
52 	bh = omfs_bread(inode->i_sb, next);
53 	if (!bh)
54 		goto out;
55 
56 	oe = (struct omfs_extent *)(&bh->b_data[OMFS_EXTENT_START]);
57 	max_extents = omfs_max_extents(sbi, OMFS_EXTENT_START);
58 
59 	for (;;) {
60 
61 		if (omfs_is_bad(sbi, (struct omfs_header *) bh->b_data, next))
62 			goto out_brelse;
63 
64 		extent_count = be32_to_cpu(oe->e_extent_count);
65 
66 		if (extent_count > max_extents)
67 			goto out_brelse;
68 
69 		last = next;
70 		next = be64_to_cpu(oe->e_next);
71 		entry = &oe->e_entry;
72 
73 		/* ignore last entry as it is the terminator */
74 		for (; extent_count > 1; extent_count--) {
75 			u64 start, count;
76 			start = be64_to_cpu(entry->e_cluster);
77 			count = be64_to_cpu(entry->e_blocks);
78 
79 			omfs_clear_range(inode->i_sb, start, (int) count);
80 			entry++;
81 		}
82 		omfs_make_empty_table(bh, (char *) oe - bh->b_data);
83 		mark_buffer_dirty(bh);
84 		brelse(bh);
85 
86 		if (last != inode->i_ino)
87 			omfs_clear_range(inode->i_sb, last, sbi->s_mirrors);
88 
89 		if (next == ~0)
90 			break;
91 
92 		bh = omfs_bread(inode->i_sb, next);
93 		if (!bh)
94 			goto out;
95 		oe = (struct omfs_extent *) (&bh->b_data[OMFS_EXTENT_CONT]);
96 		max_extents = omfs_max_extents(sbi, OMFS_EXTENT_CONT);
97 	}
98 	ret = 0;
99 out:
100 	return ret;
101 out_brelse:
102 	brelse(bh);
103 	return ret;
104 }
105 
106 static void omfs_truncate(struct inode *inode)
107 {
108 	omfs_shrink_inode(inode);
109 	mark_inode_dirty(inode);
110 }
111 
112 /*
113  * Add new blocks to the current extent, or create new entries/continuations
114  * as necessary.
115  */
116 static int omfs_grow_extent(struct inode *inode, struct omfs_extent *oe,
117 			u64 *ret_block)
118 {
119 	struct omfs_extent_entry *terminator;
120 	struct omfs_extent_entry *entry = &oe->e_entry;
121 	struct omfs_sb_info *sbi = OMFS_SB(inode->i_sb);
122 	u32 extent_count = be32_to_cpu(oe->e_extent_count);
123 	u64 new_block = 0;
124 	u32 max_count;
125 	int new_count;
126 	int ret = 0;
127 
128 	/* reached the end of the extent table with no blocks mapped.
129 	 * there are three possibilities for adding: grow last extent,
130 	 * add a new extent to the current extent table, and add a
131 	 * continuation inode.  in last two cases need an allocator for
132 	 * sbi->s_cluster_size
133 	 */
134 
135 	/* TODO: handle holes */
136 
137 	/* should always have a terminator */
138 	if (extent_count < 1)
139 		return -EIO;
140 
141 	/* trivially grow current extent, if next block is not taken */
142 	terminator = entry + extent_count - 1;
143 	if (extent_count > 1) {
144 		entry = terminator-1;
145 		new_block = be64_to_cpu(entry->e_cluster) +
146 			be64_to_cpu(entry->e_blocks);
147 
148 		if (omfs_allocate_block(inode->i_sb, new_block)) {
149 			be64_add_cpu(&entry->e_blocks, 1);
150 			terminator->e_blocks = ~(cpu_to_be64(
151 				be64_to_cpu(~terminator->e_blocks) + 1));
152 			goto out;
153 		}
154 	}
155 	max_count = omfs_max_extents(sbi, OMFS_EXTENT_START);
156 
157 	/* TODO: add a continuation block here */
158 	if (be32_to_cpu(oe->e_extent_count) > max_count-1)
159 		return -EIO;
160 
161 	/* try to allocate a new cluster */
162 	ret = omfs_allocate_range(inode->i_sb, 1, sbi->s_clustersize,
163 		&new_block, &new_count);
164 	if (ret)
165 		goto out_fail;
166 
167 	/* copy terminator down an entry */
168 	entry = terminator;
169 	terminator++;
170 	memcpy(terminator, entry, sizeof(struct omfs_extent_entry));
171 
172 	entry->e_cluster = cpu_to_be64(new_block);
173 	entry->e_blocks = cpu_to_be64((u64) new_count);
174 
175 	terminator->e_blocks = ~(cpu_to_be64(
176 		be64_to_cpu(~terminator->e_blocks) + (u64) new_count));
177 
178 	/* write in new entry */
179 	be32_add_cpu(&oe->e_extent_count, 1);
180 
181 out:
182 	*ret_block = new_block;
183 out_fail:
184 	return ret;
185 }
186 
187 /*
188  * Scans across the directory table for a given file block number.
189  * If block not found, return 0.
190  */
191 static sector_t find_block(struct inode *inode, struct omfs_extent_entry *ent,
192 			sector_t block, int count, int *left)
193 {
194 	/* count > 1 because of terminator */
195 	sector_t searched = 0;
196 	for (; count > 1; count--) {
197 		int numblocks = clus_to_blk(OMFS_SB(inode->i_sb),
198 			be64_to_cpu(ent->e_blocks));
199 
200 		if (block >= searched  &&
201 		    block < searched + numblocks) {
202 			/*
203 			 * found it at cluster + (block - searched)
204 			 * numblocks - (block - searched) is remainder
205 			 */
206 			*left = numblocks - (block - searched);
207 			return clus_to_blk(OMFS_SB(inode->i_sb),
208 				be64_to_cpu(ent->e_cluster)) +
209 				block - searched;
210 		}
211 		searched += numblocks;
212 		ent++;
213 	}
214 	return 0;
215 }
216 
217 static int omfs_get_block(struct inode *inode, sector_t block,
218 			  struct buffer_head *bh_result, int create)
219 {
220 	struct buffer_head *bh;
221 	sector_t next, offset;
222 	int ret;
223 	u64 new_block;
224 	u32 max_extents;
225 	int extent_count;
226 	struct omfs_extent *oe;
227 	struct omfs_extent_entry *entry;
228 	struct omfs_sb_info *sbi = OMFS_SB(inode->i_sb);
229 	int max_blocks = bh_result->b_size >> inode->i_blkbits;
230 	int remain;
231 
232 	ret = -EIO;
233 	bh = omfs_bread(inode->i_sb, inode->i_ino);
234 	if (!bh)
235 		goto out;
236 
237 	oe = (struct omfs_extent *)(&bh->b_data[OMFS_EXTENT_START]);
238 	max_extents = omfs_max_extents(sbi, OMFS_EXTENT_START);
239 	next = inode->i_ino;
240 
241 	for (;;) {
242 
243 		if (omfs_is_bad(sbi, (struct omfs_header *) bh->b_data, next))
244 			goto out_brelse;
245 
246 		extent_count = be32_to_cpu(oe->e_extent_count);
247 		next = be64_to_cpu(oe->e_next);
248 		entry = &oe->e_entry;
249 
250 		if (extent_count > max_extents)
251 			goto out_brelse;
252 
253 		offset = find_block(inode, entry, block, extent_count, &remain);
254 		if (offset > 0) {
255 			ret = 0;
256 			map_bh(bh_result, inode->i_sb, offset);
257 			if (remain > max_blocks)
258 				remain = max_blocks;
259 			bh_result->b_size = (remain << inode->i_blkbits);
260 			goto out_brelse;
261 		}
262 		if (next == ~0)
263 			break;
264 
265 		brelse(bh);
266 		bh = omfs_bread(inode->i_sb, next);
267 		if (!bh)
268 			goto out;
269 		oe = (struct omfs_extent *) (&bh->b_data[OMFS_EXTENT_CONT]);
270 		max_extents = omfs_max_extents(sbi, OMFS_EXTENT_CONT);
271 	}
272 	if (create) {
273 		ret = omfs_grow_extent(inode, oe, &new_block);
274 		if (ret == 0) {
275 			mark_buffer_dirty(bh);
276 			mark_inode_dirty(inode);
277 			map_bh(bh_result, inode->i_sb,
278 					clus_to_blk(sbi, new_block));
279 		}
280 	}
281 out_brelse:
282 	brelse(bh);
283 out:
284 	return ret;
285 }
286 
287 static int omfs_read_folio(struct file *file, struct folio *folio)
288 {
289 	return block_read_full_folio(folio, omfs_get_block);
290 }
291 
292 static void omfs_readahead(struct readahead_control *rac)
293 {
294 	mpage_readahead(rac, omfs_get_block);
295 }
296 
297 static int
298 omfs_writepages(struct address_space *mapping, struct writeback_control *wbc)
299 {
300 	return mpage_writepages(mapping, wbc, omfs_get_block);
301 }
302 
303 static void omfs_write_failed(struct address_space *mapping, loff_t to)
304 {
305 	struct inode *inode = mapping->host;
306 
307 	if (to > inode->i_size) {
308 		truncate_pagecache(inode, inode->i_size);
309 		omfs_truncate(inode);
310 	}
311 }
312 
313 static int omfs_write_begin(struct file *file, struct address_space *mapping,
314 			loff_t pos, unsigned len,
315 			struct page **pagep, void **fsdata)
316 {
317 	int ret;
318 
319 	ret = block_write_begin(mapping, pos, len, pagep, omfs_get_block);
320 	if (unlikely(ret))
321 		omfs_write_failed(mapping, pos + len);
322 
323 	return ret;
324 }
325 
326 static sector_t omfs_bmap(struct address_space *mapping, sector_t block)
327 {
328 	return generic_block_bmap(mapping, block, omfs_get_block);
329 }
330 
331 const struct file_operations omfs_file_operations = {
332 	.llseek = generic_file_llseek,
333 	.read_iter = generic_file_read_iter,
334 	.write_iter = generic_file_write_iter,
335 	.mmap = generic_file_mmap,
336 	.fsync = generic_file_fsync,
337 	.splice_read = filemap_splice_read,
338 };
339 
340 static int omfs_setattr(struct mnt_idmap *idmap,
341 			struct dentry *dentry, struct iattr *attr)
342 {
343 	struct inode *inode = d_inode(dentry);
344 	int error;
345 
346 	error = setattr_prepare(&nop_mnt_idmap, dentry, attr);
347 	if (error)
348 		return error;
349 
350 	if ((attr->ia_valid & ATTR_SIZE) &&
351 	    attr->ia_size != i_size_read(inode)) {
352 		error = inode_newsize_ok(inode, attr->ia_size);
353 		if (error)
354 			return error;
355 		truncate_setsize(inode, attr->ia_size);
356 		omfs_truncate(inode);
357 	}
358 
359 	setattr_copy(&nop_mnt_idmap, inode, attr);
360 	mark_inode_dirty(inode);
361 	return 0;
362 }
363 
364 const struct inode_operations omfs_file_inops = {
365 	.setattr = omfs_setattr,
366 };
367 
368 const struct address_space_operations omfs_aops = {
369 	.dirty_folio = block_dirty_folio,
370 	.invalidate_folio = block_invalidate_folio,
371 	.read_folio = omfs_read_folio,
372 	.readahead = omfs_readahead,
373 	.writepages = omfs_writepages,
374 	.write_begin = omfs_write_begin,
375 	.write_end = generic_write_end,
376 	.bmap = omfs_bmap,
377 	.migrate_folio = buffer_migrate_folio,
378 };
379 
380