diff options
Diffstat (limited to 'fs/logfs/dev_mtd.c')
-rw-r--r-- | fs/logfs/dev_mtd.c | 254 |
1 files changed, 254 insertions, 0 deletions
diff --git a/fs/logfs/dev_mtd.c b/fs/logfs/dev_mtd.c new file mode 100644 index 000000000000..cafb6ef2e05b --- /dev/null +++ b/fs/logfs/dev_mtd.c | |||
@@ -0,0 +1,254 @@ | |||
1 | /* | ||
2 | * fs/logfs/dev_mtd.c - Device access methods for MTD | ||
3 | * | ||
4 | * As should be obvious for Linux kernel code, license is GPLv2 | ||
5 | * | ||
6 | * Copyright (c) 2005-2008 Joern Engel <joern@logfs.org> | ||
7 | */ | ||
8 | #include "logfs.h" | ||
9 | #include <linux/completion.h> | ||
10 | #include <linux/mount.h> | ||
11 | #include <linux/sched.h> | ||
12 | |||
13 | #define PAGE_OFS(ofs) ((ofs) & (PAGE_SIZE-1)) | ||
14 | |||
15 | static int mtd_read(struct super_block *sb, loff_t ofs, size_t len, void *buf) | ||
16 | { | ||
17 | struct mtd_info *mtd = logfs_super(sb)->s_mtd; | ||
18 | size_t retlen; | ||
19 | int ret; | ||
20 | |||
21 | ret = mtd->read(mtd, ofs, len, &retlen, buf); | ||
22 | BUG_ON(ret == -EINVAL); | ||
23 | if (ret) | ||
24 | return ret; | ||
25 | |||
26 | /* Not sure if we should loop instead. */ | ||
27 | if (retlen != len) | ||
28 | return -EIO; | ||
29 | |||
30 | return 0; | ||
31 | } | ||
32 | |||
33 | static int mtd_write(struct super_block *sb, loff_t ofs, size_t len, void *buf) | ||
34 | { | ||
35 | struct logfs_super *super = logfs_super(sb); | ||
36 | struct mtd_info *mtd = super->s_mtd; | ||
37 | size_t retlen; | ||
38 | loff_t page_start, page_end; | ||
39 | int ret; | ||
40 | |||
41 | if (super->s_flags & LOGFS_SB_FLAG_RO) | ||
42 | return -EROFS; | ||
43 | |||
44 | BUG_ON((ofs >= mtd->size) || (len > mtd->size - ofs)); | ||
45 | BUG_ON(ofs != (ofs >> super->s_writeshift) << super->s_writeshift); | ||
46 | BUG_ON(len > PAGE_CACHE_SIZE); | ||
47 | page_start = ofs & PAGE_CACHE_MASK; | ||
48 | page_end = PAGE_CACHE_ALIGN(ofs + len) - 1; | ||
49 | ret = mtd->write(mtd, ofs, len, &retlen, buf); | ||
50 | if (ret || (retlen != len)) | ||
51 | return -EIO; | ||
52 | |||
53 | return 0; | ||
54 | } | ||
55 | |||
56 | /* | ||
57 | * For as long as I can remember (since about 2001) mtd->erase has been an | ||
58 | * asynchronous interface lacking the first driver to actually use the | ||
59 | * asynchronous properties. So just to prevent the first implementor of such | ||
60 | * a thing from breaking logfs in 2350, we do the usual pointless dance to | ||
61 | * declare a completion variable and wait for completion before returning | ||
62 | * from mtd_erase(). What an excercise in futility! | ||
63 | */ | ||
64 | static void logfs_erase_callback(struct erase_info *ei) | ||
65 | { | ||
66 | complete((struct completion *)ei->priv); | ||
67 | } | ||
68 | |||
69 | static int mtd_erase_mapping(struct super_block *sb, loff_t ofs, size_t len) | ||
70 | { | ||
71 | struct logfs_super *super = logfs_super(sb); | ||
72 | struct address_space *mapping = super->s_mapping_inode->i_mapping; | ||
73 | struct page *page; | ||
74 | pgoff_t index = ofs >> PAGE_SHIFT; | ||
75 | |||
76 | for (index = ofs >> PAGE_SHIFT; index < (ofs + len) >> PAGE_SHIFT; index++) { | ||
77 | page = find_get_page(mapping, index); | ||
78 | if (!page) | ||
79 | continue; | ||
80 | memset(page_address(page), 0xFF, PAGE_SIZE); | ||
81 | page_cache_release(page); | ||
82 | } | ||
83 | return 0; | ||
84 | } | ||
85 | |||
86 | static int mtd_erase(struct super_block *sb, loff_t ofs, size_t len, | ||
87 | int ensure_write) | ||
88 | { | ||
89 | struct mtd_info *mtd = logfs_super(sb)->s_mtd; | ||
90 | struct erase_info ei; | ||
91 | DECLARE_COMPLETION_ONSTACK(complete); | ||
92 | int ret; | ||
93 | |||
94 | BUG_ON(len % mtd->erasesize); | ||
95 | if (logfs_super(sb)->s_flags & LOGFS_SB_FLAG_RO) | ||
96 | return -EROFS; | ||
97 | |||
98 | memset(&ei, 0, sizeof(ei)); | ||
99 | ei.mtd = mtd; | ||
100 | ei.addr = ofs; | ||
101 | ei.len = len; | ||
102 | ei.callback = logfs_erase_callback; | ||
103 | ei.priv = (long)&complete; | ||
104 | ret = mtd->erase(mtd, &ei); | ||
105 | if (ret) | ||
106 | return -EIO; | ||
107 | |||
108 | wait_for_completion(&complete); | ||
109 | if (ei.state != MTD_ERASE_DONE) | ||
110 | return -EIO; | ||
111 | return mtd_erase_mapping(sb, ofs, len); | ||
112 | } | ||
113 | |||
114 | static void mtd_sync(struct super_block *sb) | ||
115 | { | ||
116 | struct mtd_info *mtd = logfs_super(sb)->s_mtd; | ||
117 | |||
118 | if (mtd->sync) | ||
119 | mtd->sync(mtd); | ||
120 | } | ||
121 | |||
122 | static int mtd_readpage(void *_sb, struct page *page) | ||
123 | { | ||
124 | struct super_block *sb = _sb; | ||
125 | int err; | ||
126 | |||
127 | err = mtd_read(sb, page->index << PAGE_SHIFT, PAGE_SIZE, | ||
128 | page_address(page)); | ||
129 | if (err == -EUCLEAN) { | ||
130 | err = 0; | ||
131 | /* FIXME: force GC this segment */ | ||
132 | } | ||
133 | if (err) { | ||
134 | ClearPageUptodate(page); | ||
135 | SetPageError(page); | ||
136 | } else { | ||
137 | SetPageUptodate(page); | ||
138 | ClearPageError(page); | ||
139 | } | ||
140 | unlock_page(page); | ||
141 | return err; | ||
142 | } | ||
143 | |||
144 | static struct page *mtd_find_first_sb(struct super_block *sb, u64 *ofs) | ||
145 | { | ||
146 | struct logfs_super *super = logfs_super(sb); | ||
147 | struct address_space *mapping = super->s_mapping_inode->i_mapping; | ||
148 | filler_t *filler = mtd_readpage; | ||
149 | struct mtd_info *mtd = super->s_mtd; | ||
150 | |||
151 | if (!mtd->block_isbad) | ||
152 | return NULL; | ||
153 | |||
154 | *ofs = 0; | ||
155 | while (mtd->block_isbad(mtd, *ofs)) { | ||
156 | *ofs += mtd->erasesize; | ||
157 | if (*ofs >= mtd->size) | ||
158 | return NULL; | ||
159 | } | ||
160 | BUG_ON(*ofs & ~PAGE_MASK); | ||
161 | return read_cache_page(mapping, *ofs >> PAGE_SHIFT, filler, sb); | ||
162 | } | ||
163 | |||
164 | static struct page *mtd_find_last_sb(struct super_block *sb, u64 *ofs) | ||
165 | { | ||
166 | struct logfs_super *super = logfs_super(sb); | ||
167 | struct address_space *mapping = super->s_mapping_inode->i_mapping; | ||
168 | filler_t *filler = mtd_readpage; | ||
169 | struct mtd_info *mtd = super->s_mtd; | ||
170 | |||
171 | if (!mtd->block_isbad) | ||
172 | return NULL; | ||
173 | |||
174 | *ofs = mtd->size - mtd->erasesize; | ||
175 | while (mtd->block_isbad(mtd, *ofs)) { | ||
176 | *ofs -= mtd->erasesize; | ||
177 | if (*ofs <= 0) | ||
178 | return NULL; | ||
179 | } | ||
180 | *ofs = *ofs + mtd->erasesize - 0x1000; | ||
181 | BUG_ON(*ofs & ~PAGE_MASK); | ||
182 | return read_cache_page(mapping, *ofs >> PAGE_SHIFT, filler, sb); | ||
183 | } | ||
184 | |||
185 | static int __mtd_writeseg(struct super_block *sb, u64 ofs, pgoff_t index, | ||
186 | size_t nr_pages) | ||
187 | { | ||
188 | struct logfs_super *super = logfs_super(sb); | ||
189 | struct address_space *mapping = super->s_mapping_inode->i_mapping; | ||
190 | struct page *page; | ||
191 | int i, err; | ||
192 | |||
193 | for (i = 0; i < nr_pages; i++) { | ||
194 | page = find_lock_page(mapping, index + i); | ||
195 | BUG_ON(!page); | ||
196 | |||
197 | err = mtd_write(sb, page->index << PAGE_SHIFT, PAGE_SIZE, | ||
198 | page_address(page)); | ||
199 | unlock_page(page); | ||
200 | page_cache_release(page); | ||
201 | if (err) | ||
202 | return err; | ||
203 | } | ||
204 | return 0; | ||
205 | } | ||
206 | |||
207 | static void mtd_writeseg(struct super_block *sb, u64 ofs, size_t len) | ||
208 | { | ||
209 | struct logfs_super *super = logfs_super(sb); | ||
210 | int head; | ||
211 | |||
212 | if (super->s_flags & LOGFS_SB_FLAG_RO) | ||
213 | return; | ||
214 | |||
215 | if (len == 0) { | ||
216 | /* This can happen when the object fit perfectly into a | ||
217 | * segment, the segment gets written per sync and subsequently | ||
218 | * closed. | ||
219 | */ | ||
220 | return; | ||
221 | } | ||
222 | head = ofs & (PAGE_SIZE - 1); | ||
223 | if (head) { | ||
224 | ofs -= head; | ||
225 | len += head; | ||
226 | } | ||
227 | len = PAGE_ALIGN(len); | ||
228 | __mtd_writeseg(sb, ofs, ofs >> PAGE_SHIFT, len >> PAGE_SHIFT); | ||
229 | } | ||
230 | |||
231 | static void mtd_put_device(struct super_block *sb) | ||
232 | { | ||
233 | put_mtd_device(logfs_super(sb)->s_mtd); | ||
234 | } | ||
235 | |||
236 | static const struct logfs_device_ops mtd_devops = { | ||
237 | .find_first_sb = mtd_find_first_sb, | ||
238 | .find_last_sb = mtd_find_last_sb, | ||
239 | .readpage = mtd_readpage, | ||
240 | .writeseg = mtd_writeseg, | ||
241 | .erase = mtd_erase, | ||
242 | .sync = mtd_sync, | ||
243 | .put_device = mtd_put_device, | ||
244 | }; | ||
245 | |||
246 | int logfs_get_sb_mtd(struct file_system_type *type, int flags, | ||
247 | int mtdnr, struct vfsmount *mnt) | ||
248 | { | ||
249 | struct mtd_info *mtd; | ||
250 | const struct logfs_device_ops *devops = &mtd_devops; | ||
251 | |||
252 | mtd = get_mtd_device(NULL, mtdnr); | ||
253 | return logfs_get_sb_device(type, flags, mtd, NULL, devops, mnt); | ||
254 | } | ||