xref: /openbmc/linux/fs/omfs/file.c (revision b6dcefde)
1 /*
2  * OMFS (as used by RIO Karma) file operations.
3  * Copyright (C) 2005 Bob Copeland <me@bobcopeland.com>
4  * Released under GPL v2.
5  */
6 
7 #include <linux/version.h>
8 #include <linux/module.h>
9 #include <linux/fs.h>
10 #include <linux/buffer_head.h>
11 #include <linux/mpage.h>
12 #include "omfs.h"
13 
14 static u32 omfs_max_extents(struct omfs_sb_info *sbi, int offset)
15 {
16 	return (sbi->s_sys_blocksize - offset -
17 		sizeof(struct omfs_extent)) /
18 		sizeof(struct omfs_extent_entry) + 1;
19 }
20 
21 void omfs_make_empty_table(struct buffer_head *bh, int offset)
22 {
23 	struct omfs_extent *oe = (struct omfs_extent *) &bh->b_data[offset];
24 
25 	oe->e_next = ~cpu_to_be64(0ULL);
26 	oe->e_extent_count = cpu_to_be32(1),
27 	oe->e_fill = cpu_to_be32(0x22),
28 	oe->e_entry.e_cluster = ~cpu_to_be64(0ULL);
29 	oe->e_entry.e_blocks = ~cpu_to_be64(0ULL);
30 }
31 
32 int omfs_shrink_inode(struct inode *inode)
33 {
34 	struct omfs_sb_info *sbi = OMFS_SB(inode->i_sb);
35 	struct omfs_extent *oe;
36 	struct omfs_extent_entry *entry;
37 	struct buffer_head *bh;
38 	u64 next, last;
39 	u32 extent_count;
40 	u32 max_extents;
41 	int ret;
42 
43 	/* traverse extent table, freeing each entry that is greater
44 	 * than inode->i_size;
45 	 */
46 	next = inode->i_ino;
47 
48 	/* only support truncate -> 0 for now */
49 	ret = -EIO;
50 	if (inode->i_size != 0)
51 		goto out;
52 
53 	bh = sb_bread(inode->i_sb, clus_to_blk(sbi, next));
54 	if (!bh)
55 		goto out;
56 
57 	oe = (struct omfs_extent *)(&bh->b_data[OMFS_EXTENT_START]);
58 	max_extents = omfs_max_extents(sbi, OMFS_EXTENT_START);
59 
60 	for (;;) {
61 
62 		if (omfs_is_bad(sbi, (struct omfs_header *) bh->b_data, next))
63 			goto out_brelse;
64 
65 		extent_count = be32_to_cpu(oe->e_extent_count);
66 
67 		if (extent_count > max_extents)
68 			goto out_brelse;
69 
70 		last = next;
71 		next = be64_to_cpu(oe->e_next);
72 		entry = &oe->e_entry;
73 
74 		/* ignore last entry as it is the terminator */
75 		for (; extent_count > 1; extent_count--) {
76 			u64 start, count;
77 			start = be64_to_cpu(entry->e_cluster);
78 			count = be64_to_cpu(entry->e_blocks);
79 
80 			omfs_clear_range(inode->i_sb, start, (int) count);
81 			entry++;
82 		}
83 		omfs_make_empty_table(bh, (char *) oe - bh->b_data);
84 		mark_buffer_dirty(bh);
85 		brelse(bh);
86 
87 		if (last != inode->i_ino)
88 			omfs_clear_range(inode->i_sb, last, sbi->s_mirrors);
89 
90 		if (next == ~0)
91 			break;
92 
93 		bh = sb_bread(inode->i_sb, clus_to_blk(sbi, next));
94 		if (!bh)
95 			goto out;
96 		oe = (struct omfs_extent *) (&bh->b_data[OMFS_EXTENT_CONT]);
97 		max_extents = omfs_max_extents(sbi, OMFS_EXTENT_CONT);
98 	}
99 	ret = 0;
100 out:
101 	return ret;
102 out_brelse:
103 	brelse(bh);
104 	return ret;
105 }
106 
107 static void omfs_truncate(struct inode *inode)
108 {
109 	omfs_shrink_inode(inode);
110 	mark_inode_dirty(inode);
111 }
112 
113 /*
114  * Add new blocks to the current extent, or create new entries/continuations
115  * as necessary.
116  */
117 static int omfs_grow_extent(struct inode *inode, struct omfs_extent *oe,
118 			u64 *ret_block)
119 {
120 	struct omfs_extent_entry *terminator;
121 	struct omfs_extent_entry *entry = &oe->e_entry;
122 	struct omfs_sb_info *sbi = OMFS_SB(inode->i_sb);
123 	u32 extent_count = be32_to_cpu(oe->e_extent_count);
124 	u64 new_block = 0;
125 	u32 max_count;
126 	int new_count;
127 	int ret = 0;
128 
129 	/* reached the end of the extent table with no blocks mapped.
130 	 * there are three possibilities for adding: grow last extent,
131 	 * add a new extent to the current extent table, and add a
132 	 * continuation inode.  in last two cases need an allocator for
133 	 * sbi->s_cluster_size
134 	 */
135 
136 	/* TODO: handle holes */
137 
138 	/* should always have a terminator */
139 	if (extent_count < 1)
140 		return -EIO;
141 
142 	/* trivially grow current extent, if next block is not taken */
143 	terminator = entry + extent_count - 1;
144 	if (extent_count > 1) {
145 		entry = terminator-1;
146 		new_block = be64_to_cpu(entry->e_cluster) +
147 			be64_to_cpu(entry->e_blocks);
148 
149 		if (omfs_allocate_block(inode->i_sb, new_block)) {
150 			entry->e_blocks =
151 				cpu_to_be64(be64_to_cpu(entry->e_blocks) + 1);
152 			terminator->e_blocks = ~(cpu_to_be64(
153 				be64_to_cpu(~terminator->e_blocks) + 1));
154 			goto out;
155 		}
156 	}
157 	max_count = omfs_max_extents(sbi, OMFS_EXTENT_START);
158 
159 	/* TODO: add a continuation block here */
160 	if (be32_to_cpu(oe->e_extent_count) > max_count-1)
161 		return -EIO;
162 
163 	/* try to allocate a new cluster */
164 	ret = omfs_allocate_range(inode->i_sb, 1, sbi->s_clustersize,
165 		&new_block, &new_count);
166 	if (ret)
167 		goto out_fail;
168 
169 	/* copy terminator down an entry */
170 	entry = terminator;
171 	terminator++;
172 	memcpy(terminator, entry, sizeof(struct omfs_extent_entry));
173 
174 	entry->e_cluster = cpu_to_be64(new_block);
175 	entry->e_blocks = cpu_to_be64((u64) new_count);
176 
177 	terminator->e_blocks = ~(cpu_to_be64(
178 		be64_to_cpu(~terminator->e_blocks) + (u64) new_count));
179 
180 	/* write in new entry */
181 	oe->e_extent_count = cpu_to_be32(1 + be32_to_cpu(oe->e_extent_count));
182 
183 out:
184 	*ret_block = new_block;
185 out_fail:
186 	return ret;
187 }
188 
189 /*
190  * Scans across the directory table for a given file block number.
191  * If block not found, return 0.
192  */
193 static sector_t find_block(struct inode *inode, struct omfs_extent_entry *ent,
194 			sector_t block, int count, int *left)
195 {
196 	/* count > 1 because of terminator */
197 	sector_t searched = 0;
198 	for (; count > 1; count--) {
199 		int numblocks = clus_to_blk(OMFS_SB(inode->i_sb),
200 			be64_to_cpu(ent->e_blocks));
201 
202 		if (block >= searched  &&
203 		    block < searched + numblocks) {
204 			/*
205 			 * found it at cluster + (block - searched)
206 			 * numblocks - (block - searched) is remainder
207 			 */
208 			*left = numblocks - (block - searched);
209 			return clus_to_blk(OMFS_SB(inode->i_sb),
210 				be64_to_cpu(ent->e_cluster)) +
211 				block - searched;
212 		}
213 		searched += numblocks;
214 		ent++;
215 	}
216 	return 0;
217 }
218 
219 static int omfs_get_block(struct inode *inode, sector_t block,
220 			  struct buffer_head *bh_result, int create)
221 {
222 	struct buffer_head *bh;
223 	sector_t next, offset;
224 	int ret;
225 	u64 new_block;
226 	u32 max_extents;
227 	int extent_count;
228 	struct omfs_extent *oe;
229 	struct omfs_extent_entry *entry;
230 	struct omfs_sb_info *sbi = OMFS_SB(inode->i_sb);
231 	int max_blocks = bh_result->b_size >> inode->i_blkbits;
232 	int remain;
233 
234 	ret = -EIO;
235 	bh = sb_bread(inode->i_sb, clus_to_blk(sbi, inode->i_ino));
236 	if (!bh)
237 		goto out;
238 
239 	oe = (struct omfs_extent *)(&bh->b_data[OMFS_EXTENT_START]);
240 	max_extents = omfs_max_extents(sbi, OMFS_EXTENT_START);
241 	next = inode->i_ino;
242 
243 	for (;;) {
244 
245 		if (omfs_is_bad(sbi, (struct omfs_header *) bh->b_data, next))
246 			goto out_brelse;
247 
248 		extent_count = be32_to_cpu(oe->e_extent_count);
249 		next = be64_to_cpu(oe->e_next);
250 		entry = &oe->e_entry;
251 
252 		if (extent_count > max_extents)
253 			goto out_brelse;
254 
255 		offset = find_block(inode, entry, block, extent_count, &remain);
256 		if (offset > 0) {
257 			ret = 0;
258 			map_bh(bh_result, inode->i_sb, offset);
259 			if (remain > max_blocks)
260 				remain = max_blocks;
261 			bh_result->b_size = (remain << inode->i_blkbits);
262 			goto out_brelse;
263 		}
264 		if (next == ~0)
265 			break;
266 
267 		brelse(bh);
268 		bh = sb_bread(inode->i_sb, clus_to_blk(sbi, next));
269 		if (!bh)
270 			goto out;
271 		oe = (struct omfs_extent *) (&bh->b_data[OMFS_EXTENT_CONT]);
272 		max_extents = omfs_max_extents(sbi, OMFS_EXTENT_CONT);
273 	}
274 	if (create) {
275 		ret = omfs_grow_extent(inode, oe, &new_block);
276 		if (ret == 0) {
277 			mark_buffer_dirty(bh);
278 			mark_inode_dirty(inode);
279 			map_bh(bh_result, inode->i_sb,
280 					clus_to_blk(sbi, new_block));
281 		}
282 	}
283 out_brelse:
284 	brelse(bh);
285 out:
286 	return ret;
287 }
288 
289 static int omfs_readpage(struct file *file, struct page *page)
290 {
291 	return block_read_full_page(page, omfs_get_block);
292 }
293 
294 static int omfs_readpages(struct file *file, struct address_space *mapping,
295 		struct list_head *pages, unsigned nr_pages)
296 {
297 	return mpage_readpages(mapping, pages, nr_pages, omfs_get_block);
298 }
299 
300 static int omfs_writepage(struct page *page, struct writeback_control *wbc)
301 {
302 	return block_write_full_page(page, omfs_get_block, wbc);
303 }
304 
305 static int
306 omfs_writepages(struct address_space *mapping, struct writeback_control *wbc)
307 {
308 	return mpage_writepages(mapping, wbc, omfs_get_block);
309 }
310 
311 static int omfs_write_begin(struct file *file, struct address_space *mapping,
312 			loff_t pos, unsigned len, unsigned flags,
313 			struct page **pagep, void **fsdata)
314 {
315 	*pagep = NULL;
316 	return block_write_begin(file, mapping, pos, len, flags,
317 				pagep, fsdata, omfs_get_block);
318 }
319 
320 static sector_t omfs_bmap(struct address_space *mapping, sector_t block)
321 {
322 	return generic_block_bmap(mapping, block, omfs_get_block);
323 }
324 
325 const struct file_operations omfs_file_operations = {
326 	.llseek = generic_file_llseek,
327 	.read = do_sync_read,
328 	.write = do_sync_write,
329 	.aio_read = generic_file_aio_read,
330 	.aio_write = generic_file_aio_write,
331 	.mmap = generic_file_mmap,
332 	.fsync = simple_fsync,
333 	.splice_read = generic_file_splice_read,
334 };
335 
336 const struct inode_operations omfs_file_inops = {
337 	.truncate = omfs_truncate
338 };
339 
340 const struct address_space_operations omfs_aops = {
341 	.readpage = omfs_readpage,
342 	.readpages = omfs_readpages,
343 	.writepage = omfs_writepage,
344 	.writepages = omfs_writepages,
345 	.sync_page = block_sync_page,
346 	.write_begin = omfs_write_begin,
347 	.write_end = generic_write_end,
348 	.bmap = omfs_bmap,
349 };
350 
351