Commit | Line | Data |
---|---|---|
5db53f3e JE |
1 | /* |
2 | * fs/logfs/inode.c - inode handling code | |
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" | |
5a0e3ad6 | 9 | #include <linux/slab.h> |
5db53f3e JE |
10 | #include <linux/writeback.h> |
11 | #include <linux/backing-dev.h> | |
12 | ||
13 | /* | |
14 | * How soon to reuse old inode numbers? LogFS doesn't store deleted inodes | |
15 | * on the medium. It therefore also lacks a method to store the previous | |
16 | * generation number for deleted inodes. Instead a single generation number | |
17 | * is stored which will be used for new inodes. Being just a 32bit counter, | |
18 | * this can obvious wrap relatively quickly. So we only reuse inodes if we | |
19 | * know that a fair number of inodes can be created before we have to increment | |
20 | * the generation again - effectively adding some bits to the counter. | |
21 | * But being too aggressive here means we keep a very large and very sparse | |
22 | * inode file, wasting space on indirect blocks. | |
23 | * So what is a good value? Beats me. 64k seems moderately bad on both | |
24 | * fronts, so let's use that for now... | |
25 | * | |
26 | * NFS sucks, as everyone already knows. | |
27 | */ | |
28 | #define INOS_PER_WRAP (0x10000) | |
29 | ||
30 | /* | |
31 | * Logfs' requirement to read inodes for garbage collection makes life a bit | |
32 | * harder. GC may have to read inodes that are in I_FREEING state, when they | |
33 | * are being written out - and waiting for GC to make progress, naturally. | |
34 | * | |
35 | * So we cannot just call iget() or some variant of it, but first have to check | |
36 | * wether the inode in question might be in I_FREEING state. Therefore we | |
37 | * maintain our own per-sb list of "almost deleted" inodes and check against | |
38 | * that list first. Normally this should be at most 1-2 entries long. | |
39 | * | |
40 | * Also, inodes have logfs-specific reference counting on top of what the vfs | |
41 | * does. When .destroy_inode is called, normally the reference count will drop | |
42 | * to zero and the inode gets deleted. But if GC accessed the inode, its | |
43 | * refcount will remain nonzero and final deletion will have to wait. | |
44 | * | |
45 | * As a result we have two sets of functions to get/put inodes: | |
46 | * logfs_safe_iget/logfs_safe_iput - safe to call from GC context | |
47 | * logfs_iget/iput - normal version | |
48 | */ | |
49 | static struct kmem_cache *logfs_inode_cache; | |
50 | ||
51 | static DEFINE_SPINLOCK(logfs_inode_lock); | |
52 | ||
53 | static void logfs_inode_setops(struct inode *inode) | |
54 | { | |
55 | switch (inode->i_mode & S_IFMT) { | |
56 | case S_IFDIR: | |
57 | inode->i_op = &logfs_dir_iops; | |
58 | inode->i_fop = &logfs_dir_fops; | |
59 | inode->i_mapping->a_ops = &logfs_reg_aops; | |
60 | break; | |
61 | case S_IFREG: | |
62 | inode->i_op = &logfs_reg_iops; | |
63 | inode->i_fop = &logfs_reg_fops; | |
64 | inode->i_mapping->a_ops = &logfs_reg_aops; | |
65 | break; | |
66 | case S_IFLNK: | |
67 | inode->i_op = &logfs_symlink_iops; | |
68 | inode->i_mapping->a_ops = &logfs_reg_aops; | |
69 | break; | |
70 | case S_IFSOCK: /* fall through */ | |
71 | case S_IFBLK: /* fall through */ | |
72 | case S_IFCHR: /* fall through */ | |
73 | case S_IFIFO: | |
74 | init_special_inode(inode, inode->i_mode, inode->i_rdev); | |
75 | break; | |
76 | default: | |
77 | BUG(); | |
78 | } | |
79 | } | |
80 | ||
81 | static struct inode *__logfs_iget(struct super_block *sb, ino_t ino) | |
82 | { | |
83 | struct inode *inode = iget_locked(sb, ino); | |
84 | int err; | |
85 | ||
86 | if (!inode) | |
87 | return ERR_PTR(-ENOMEM); | |
88 | if (!(inode->i_state & I_NEW)) | |
89 | return inode; | |
90 | ||
91 | err = logfs_read_inode(inode); | |
92 | if (err || inode->i_nlink == 0) { | |
93 | /* inode->i_nlink == 0 can be true when called from | |
94 | * block validator */ | |
95 | /* set i_nlink to 0 to prevent caching */ | |
96 | inode->i_nlink = 0; | |
97 | logfs_inode(inode)->li_flags |= LOGFS_IF_ZOMBIE; | |
98 | iget_failed(inode); | |
99 | if (!err) | |
100 | err = -ENOENT; | |
101 | return ERR_PTR(err); | |
102 | } | |
103 | ||
104 | logfs_inode_setops(inode); | |
105 | unlock_new_inode(inode); | |
106 | return inode; | |
107 | } | |
108 | ||
109 | struct inode *logfs_iget(struct super_block *sb, ino_t ino) | |
110 | { | |
111 | BUG_ON(ino == LOGFS_INO_MASTER); | |
112 | BUG_ON(ino == LOGFS_INO_SEGFILE); | |
113 | return __logfs_iget(sb, ino); | |
114 | } | |
115 | ||
116 | /* | |
117 | * is_cached is set to 1 if we hand out a cached inode, 0 otherwise. | |
118 | * this allows logfs_iput to do the right thing later | |
119 | */ | |
120 | struct inode *logfs_safe_iget(struct super_block *sb, ino_t ino, int *is_cached) | |
121 | { | |
122 | struct logfs_super *super = logfs_super(sb); | |
123 | struct logfs_inode *li; | |
124 | ||
125 | if (ino == LOGFS_INO_MASTER) | |
126 | return super->s_master_inode; | |
127 | if (ino == LOGFS_INO_SEGFILE) | |
128 | return super->s_segfile_inode; | |
129 | ||
130 | spin_lock(&logfs_inode_lock); | |
131 | list_for_each_entry(li, &super->s_freeing_list, li_freeing_list) | |
132 | if (li->vfs_inode.i_ino == ino) { | |
133 | li->li_refcount++; | |
134 | spin_unlock(&logfs_inode_lock); | |
135 | *is_cached = 1; | |
136 | return &li->vfs_inode; | |
137 | } | |
138 | spin_unlock(&logfs_inode_lock); | |
139 | ||
140 | *is_cached = 0; | |
141 | return __logfs_iget(sb, ino); | |
142 | } | |
143 | ||
144 | static void __logfs_destroy_inode(struct inode *inode) | |
145 | { | |
146 | struct logfs_inode *li = logfs_inode(inode); | |
147 | ||
148 | BUG_ON(li->li_block); | |
149 | list_del(&li->li_freeing_list); | |
150 | kmem_cache_free(logfs_inode_cache, li); | |
151 | } | |
152 | ||
153 | static void logfs_destroy_inode(struct inode *inode) | |
154 | { | |
155 | struct logfs_inode *li = logfs_inode(inode); | |
156 | ||
157 | BUG_ON(list_empty(&li->li_freeing_list)); | |
158 | spin_lock(&logfs_inode_lock); | |
159 | li->li_refcount--; | |
160 | if (li->li_refcount == 0) | |
161 | __logfs_destroy_inode(inode); | |
162 | spin_unlock(&logfs_inode_lock); | |
163 | } | |
164 | ||
165 | void logfs_safe_iput(struct inode *inode, int is_cached) | |
166 | { | |
167 | if (inode->i_ino == LOGFS_INO_MASTER) | |
168 | return; | |
169 | if (inode->i_ino == LOGFS_INO_SEGFILE) | |
170 | return; | |
171 | ||
172 | if (is_cached) { | |
173 | logfs_destroy_inode(inode); | |
174 | return; | |
175 | } | |
176 | ||
177 | iput(inode); | |
178 | } | |
179 | ||
180 | static void logfs_init_inode(struct super_block *sb, struct inode *inode) | |
181 | { | |
182 | struct logfs_inode *li = logfs_inode(inode); | |
183 | int i; | |
184 | ||
185 | li->li_flags = 0; | |
186 | li->li_height = 0; | |
187 | li->li_used_bytes = 0; | |
188 | li->li_block = NULL; | |
189 | inode->i_uid = 0; | |
190 | inode->i_gid = 0; | |
191 | inode->i_size = 0; | |
192 | inode->i_blocks = 0; | |
193 | inode->i_ctime = CURRENT_TIME; | |
194 | inode->i_mtime = CURRENT_TIME; | |
195 | inode->i_nlink = 1; | |
196 | INIT_LIST_HEAD(&li->li_freeing_list); | |
197 | ||
198 | for (i = 0; i < LOGFS_EMBEDDED_FIELDS; i++) | |
199 | li->li_data[i] = 0; | |
200 | ||
201 | return; | |
202 | } | |
203 | ||
204 | static struct inode *logfs_alloc_inode(struct super_block *sb) | |
205 | { | |
206 | struct logfs_inode *li; | |
207 | ||
208 | li = kmem_cache_alloc(logfs_inode_cache, GFP_NOFS); | |
209 | if (!li) | |
210 | return NULL; | |
211 | logfs_init_inode(sb, &li->vfs_inode); | |
212 | return &li->vfs_inode; | |
213 | } | |
214 | ||
215 | /* | |
216 | * In logfs inodes are written to an inode file. The inode file, like any | |
217 | * other file, is managed with a inode. The inode file's inode, aka master | |
218 | * inode, requires special handling in several respects. First, it cannot be | |
219 | * written to the inode file, so it is stored in the journal instead. | |
220 | * | |
221 | * Secondly, this inode cannot be written back and destroyed before all other | |
222 | * inodes have been written. The ordering is important. Linux' VFS is happily | |
223 | * unaware of the ordering constraint and would ordinarily destroy the master | |
224 | * inode at umount time while other inodes are still in use and dirty. Not | |
225 | * good. | |
226 | * | |
227 | * So logfs makes sure the master inode is not written until all other inodes | |
228 | * have been destroyed. Sadly, this method has another side-effect. The VFS | |
229 | * will notice one remaining inode and print a frightening warning message. | |
230 | * Worse, it is impossible to judge whether such a warning was caused by the | |
231 | * master inode or any other inodes have leaked as well. | |
232 | * | |
233 | * Our attempt of solving this is with logfs_new_meta_inode() below. Its | |
234 | * purpose is to create a new inode that will not trigger the warning if such | |
235 | * an inode is still in use. An ugly hack, no doubt. Suggections for | |
236 | * improvement are welcome. | |
237 | */ | |
238 | struct inode *logfs_new_meta_inode(struct super_block *sb, u64 ino) | |
239 | { | |
240 | struct inode *inode; | |
241 | ||
242 | inode = logfs_alloc_inode(sb); | |
243 | if (!inode) | |
244 | return ERR_PTR(-ENOMEM); | |
245 | ||
246 | inode->i_mode = S_IFREG; | |
247 | inode->i_ino = ino; | |
248 | inode->i_sb = sb; | |
249 | ||
250 | /* This is a blatant copy of alloc_inode code. We'd need alloc_inode | |
251 | * to be nonstatic, alas. */ | |
252 | { | |
253 | struct address_space * const mapping = &inode->i_data; | |
254 | ||
255 | mapping->a_ops = &logfs_reg_aops; | |
256 | mapping->host = inode; | |
257 | mapping->flags = 0; | |
258 | mapping_set_gfp_mask(mapping, GFP_NOFS); | |
259 | mapping->assoc_mapping = NULL; | |
260 | mapping->backing_dev_info = &default_backing_dev_info; | |
261 | inode->i_mapping = mapping; | |
262 | inode->i_nlink = 1; | |
263 | } | |
264 | ||
265 | return inode; | |
266 | } | |
267 | ||
268 | struct inode *logfs_read_meta_inode(struct super_block *sb, u64 ino) | |
269 | { | |
270 | struct inode *inode; | |
271 | int err; | |
272 | ||
273 | inode = logfs_new_meta_inode(sb, ino); | |
274 | if (IS_ERR(inode)) | |
275 | return inode; | |
276 | ||
277 | err = logfs_read_inode(inode); | |
278 | if (err) { | |
279 | destroy_meta_inode(inode); | |
280 | return ERR_PTR(err); | |
281 | } | |
282 | logfs_inode_setops(inode); | |
283 | return inode; | |
284 | } | |
285 | ||
66b89159 | 286 | static int logfs_write_inode(struct inode *inode, struct writeback_control *wbc) |
5db53f3e JE |
287 | { |
288 | int ret; | |
289 | long flags = WF_LOCK; | |
290 | ||
291 | /* Can only happen if creat() failed. Safe to skip. */ | |
292 | if (logfs_inode(inode)->li_flags & LOGFS_IF_STILLBORN) | |
293 | return 0; | |
294 | ||
295 | ret = __logfs_write_inode(inode, flags); | |
296 | LOGFS_BUG_ON(ret, inode->i_sb); | |
297 | return ret; | |
298 | } | |
299 | ||
300 | void destroy_meta_inode(struct inode *inode) | |
301 | { | |
302 | if (inode) { | |
303 | if (inode->i_data.nrpages) | |
304 | truncate_inode_pages(&inode->i_data, 0); | |
305 | logfs_clear_inode(inode); | |
306 | kmem_cache_free(logfs_inode_cache, logfs_inode(inode)); | |
307 | } | |
308 | } | |
309 | ||
310 | /* called with inode_lock held */ | |
311 | static void logfs_drop_inode(struct inode *inode) | |
312 | { | |
313 | struct logfs_super *super = logfs_super(inode->i_sb); | |
314 | struct logfs_inode *li = logfs_inode(inode); | |
315 | ||
316 | spin_lock(&logfs_inode_lock); | |
317 | list_move(&li->li_freeing_list, &super->s_freeing_list); | |
318 | spin_unlock(&logfs_inode_lock); | |
319 | generic_drop_inode(inode); | |
320 | } | |
321 | ||
322 | static void logfs_set_ino_generation(struct super_block *sb, | |
323 | struct inode *inode) | |
324 | { | |
325 | struct logfs_super *super = logfs_super(sb); | |
326 | u64 ino; | |
327 | ||
328 | mutex_lock(&super->s_journal_mutex); | |
329 | ino = logfs_seek_hole(super->s_master_inode, super->s_last_ino); | |
330 | super->s_last_ino = ino; | |
331 | super->s_inos_till_wrap--; | |
332 | if (super->s_inos_till_wrap < 0) { | |
333 | super->s_last_ino = LOGFS_RESERVED_INOS; | |
334 | super->s_generation++; | |
335 | super->s_inos_till_wrap = INOS_PER_WRAP; | |
336 | } | |
337 | inode->i_ino = ino; | |
338 | inode->i_generation = super->s_generation; | |
339 | mutex_unlock(&super->s_journal_mutex); | |
340 | } | |
341 | ||
342 | struct inode *logfs_new_inode(struct inode *dir, int mode) | |
343 | { | |
344 | struct super_block *sb = dir->i_sb; | |
345 | struct inode *inode; | |
346 | ||
347 | inode = new_inode(sb); | |
348 | if (!inode) | |
349 | return ERR_PTR(-ENOMEM); | |
350 | ||
351 | logfs_init_inode(sb, inode); | |
352 | ||
353 | /* inherit parent flags */ | |
354 | logfs_inode(inode)->li_flags |= | |
355 | logfs_inode(dir)->li_flags & LOGFS_FL_INHERITED; | |
356 | ||
357 | inode->i_mode = mode; | |
358 | logfs_set_ino_generation(sb, inode); | |
359 | ||
360 | inode->i_uid = current_fsuid(); | |
361 | inode->i_gid = current_fsgid(); | |
362 | if (dir->i_mode & S_ISGID) { | |
363 | inode->i_gid = dir->i_gid; | |
364 | if (S_ISDIR(mode)) | |
365 | inode->i_mode |= S_ISGID; | |
366 | } | |
367 | ||
368 | logfs_inode_setops(inode); | |
369 | insert_inode_hash(inode); | |
370 | ||
371 | return inode; | |
372 | } | |
373 | ||
374 | static void logfs_init_once(void *_li) | |
375 | { | |
376 | struct logfs_inode *li = _li; | |
377 | int i; | |
378 | ||
379 | li->li_flags = 0; | |
380 | li->li_used_bytes = 0; | |
381 | li->li_refcount = 1; | |
382 | for (i = 0; i < LOGFS_EMBEDDED_FIELDS; i++) | |
383 | li->li_data[i] = 0; | |
384 | inode_init_once(&li->vfs_inode); | |
385 | } | |
386 | ||
387 | static int logfs_sync_fs(struct super_block *sb, int wait) | |
388 | { | |
389 | /* FIXME: write anchor */ | |
390 | logfs_super(sb)->s_devops->sync(sb); | |
391 | return 0; | |
392 | } | |
393 | ||
394 | const struct super_operations logfs_super_operations = { | |
395 | .alloc_inode = logfs_alloc_inode, | |
396 | .clear_inode = logfs_clear_inode, | |
397 | .delete_inode = logfs_delete_inode, | |
398 | .destroy_inode = logfs_destroy_inode, | |
399 | .drop_inode = logfs_drop_inode, | |
400 | .write_inode = logfs_write_inode, | |
401 | .statfs = logfs_statfs, | |
402 | .sync_fs = logfs_sync_fs, | |
403 | }; | |
404 | ||
405 | int logfs_init_inode_cache(void) | |
406 | { | |
407 | logfs_inode_cache = kmem_cache_create("logfs_inode_cache", | |
408 | sizeof(struct logfs_inode), 0, SLAB_RECLAIM_ACCOUNT, | |
409 | logfs_init_once); | |
410 | if (!logfs_inode_cache) | |
411 | return -ENOMEM; | |
412 | return 0; | |
413 | } | |
414 | ||
415 | void logfs_destroy_inode_cache(void) | |
416 | { | |
417 | kmem_cache_destroy(logfs_inode_cache); | |
418 | } |