Joern Engel | 5db53f3 | 2009-11-20 20:13:39 +0100 | [diff] [blame] | 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" |
Tejun Heo | 5a0e3ad | 2010-03-24 17:04:11 +0900 | [diff] [blame] | 9 | #include <linux/slab.h> |
Joern Engel | 5db53f3 | 2009-11-20 20:13:39 +0100 | [diff] [blame] | 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 */ |
Miklos Szeredi | 6d6b77f | 2011-10-28 14:13:28 +0200 | [diff] [blame] | 96 | clear_nlink(inode); |
Joern Engel | 5db53f3 | 2009-11-20 20:13:39 +0100 | [diff] [blame] | 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 | |
Nick Piggin | fa0d7e3d | 2011-01-07 17:49:49 +1100 | [diff] [blame] | 144 | static void logfs_i_callback(struct rcu_head *head) |
| 145 | { |
| 146 | struct inode *inode = container_of(head, struct inode, i_rcu); |
Nick Piggin | fa0d7e3d | 2011-01-07 17:49:49 +1100 | [diff] [blame] | 147 | kmem_cache_free(logfs_inode_cache, logfs_inode(inode)); |
| 148 | } |
| 149 | |
Joern Engel | 5db53f3 | 2009-11-20 20:13:39 +0100 | [diff] [blame] | 150 | static void __logfs_destroy_inode(struct inode *inode) |
| 151 | { |
| 152 | struct logfs_inode *li = logfs_inode(inode); |
| 153 | |
| 154 | BUG_ON(li->li_block); |
| 155 | list_del(&li->li_freeing_list); |
Nick Piggin | fa0d7e3d | 2011-01-07 17:49:49 +1100 | [diff] [blame] | 156 | call_rcu(&inode->i_rcu, logfs_i_callback); |
Joern Engel | 5db53f3 | 2009-11-20 20:13:39 +0100 | [diff] [blame] | 157 | } |
| 158 | |
| 159 | static void logfs_destroy_inode(struct inode *inode) |
| 160 | { |
| 161 | struct logfs_inode *li = logfs_inode(inode); |
| 162 | |
| 163 | BUG_ON(list_empty(&li->li_freeing_list)); |
| 164 | spin_lock(&logfs_inode_lock); |
| 165 | li->li_refcount--; |
| 166 | if (li->li_refcount == 0) |
| 167 | __logfs_destroy_inode(inode); |
| 168 | spin_unlock(&logfs_inode_lock); |
| 169 | } |
| 170 | |
| 171 | void logfs_safe_iput(struct inode *inode, int is_cached) |
| 172 | { |
| 173 | if (inode->i_ino == LOGFS_INO_MASTER) |
| 174 | return; |
| 175 | if (inode->i_ino == LOGFS_INO_SEGFILE) |
| 176 | return; |
| 177 | |
| 178 | if (is_cached) { |
| 179 | logfs_destroy_inode(inode); |
| 180 | return; |
| 181 | } |
| 182 | |
| 183 | iput(inode); |
| 184 | } |
| 185 | |
| 186 | static void logfs_init_inode(struct super_block *sb, struct inode *inode) |
| 187 | { |
| 188 | struct logfs_inode *li = logfs_inode(inode); |
| 189 | int i; |
| 190 | |
| 191 | li->li_flags = 0; |
| 192 | li->li_height = 0; |
| 193 | li->li_used_bytes = 0; |
| 194 | li->li_block = NULL; |
| 195 | inode->i_uid = 0; |
| 196 | inode->i_gid = 0; |
| 197 | inode->i_size = 0; |
| 198 | inode->i_blocks = 0; |
| 199 | inode->i_ctime = CURRENT_TIME; |
| 200 | inode->i_mtime = CURRENT_TIME; |
Prasad Joshi | 2479753 | 2010-05-04 22:13:59 +0200 | [diff] [blame] | 201 | li->li_refcount = 1; |
Joern Engel | 5db53f3 | 2009-11-20 20:13:39 +0100 | [diff] [blame] | 202 | INIT_LIST_HEAD(&li->li_freeing_list); |
| 203 | |
| 204 | for (i = 0; i < LOGFS_EMBEDDED_FIELDS; i++) |
| 205 | li->li_data[i] = 0; |
| 206 | |
| 207 | return; |
| 208 | } |
| 209 | |
| 210 | static struct inode *logfs_alloc_inode(struct super_block *sb) |
| 211 | { |
| 212 | struct logfs_inode *li; |
| 213 | |
| 214 | li = kmem_cache_alloc(logfs_inode_cache, GFP_NOFS); |
| 215 | if (!li) |
| 216 | return NULL; |
| 217 | logfs_init_inode(sb, &li->vfs_inode); |
| 218 | return &li->vfs_inode; |
| 219 | } |
| 220 | |
| 221 | /* |
| 222 | * In logfs inodes are written to an inode file. The inode file, like any |
| 223 | * other file, is managed with a inode. The inode file's inode, aka master |
| 224 | * inode, requires special handling in several respects. First, it cannot be |
| 225 | * written to the inode file, so it is stored in the journal instead. |
| 226 | * |
| 227 | * Secondly, this inode cannot be written back and destroyed before all other |
| 228 | * inodes have been written. The ordering is important. Linux' VFS is happily |
| 229 | * unaware of the ordering constraint and would ordinarily destroy the master |
| 230 | * inode at umount time while other inodes are still in use and dirty. Not |
| 231 | * good. |
| 232 | * |
| 233 | * So logfs makes sure the master inode is not written until all other inodes |
| 234 | * have been destroyed. Sadly, this method has another side-effect. The VFS |
| 235 | * will notice one remaining inode and print a frightening warning message. |
| 236 | * Worse, it is impossible to judge whether such a warning was caused by the |
| 237 | * master inode or any other inodes have leaked as well. |
| 238 | * |
| 239 | * Our attempt of solving this is with logfs_new_meta_inode() below. Its |
| 240 | * purpose is to create a new inode that will not trigger the warning if such |
| 241 | * an inode is still in use. An ugly hack, no doubt. Suggections for |
| 242 | * improvement are welcome. |
Al Viro | 8e22c1a | 2010-06-07 12:22:31 -0400 | [diff] [blame] | 243 | * |
| 244 | * AV: that's what ->put_super() is for... |
Joern Engel | 5db53f3 | 2009-11-20 20:13:39 +0100 | [diff] [blame] | 245 | */ |
| 246 | struct inode *logfs_new_meta_inode(struct super_block *sb, u64 ino) |
| 247 | { |
| 248 | struct inode *inode; |
| 249 | |
Al Viro | 8e22c1a | 2010-06-07 12:22:31 -0400 | [diff] [blame] | 250 | inode = new_inode(sb); |
Joern Engel | 5db53f3 | 2009-11-20 20:13:39 +0100 | [diff] [blame] | 251 | if (!inode) |
| 252 | return ERR_PTR(-ENOMEM); |
| 253 | |
| 254 | inode->i_mode = S_IFREG; |
| 255 | inode->i_ino = ino; |
Al Viro | 8e22c1a | 2010-06-07 12:22:31 -0400 | [diff] [blame] | 256 | inode->i_data.a_ops = &logfs_reg_aops; |
| 257 | mapping_set_gfp_mask(&inode->i_data, GFP_NOFS); |
Joern Engel | 5db53f3 | 2009-11-20 20:13:39 +0100 | [diff] [blame] | 258 | |
| 259 | return inode; |
| 260 | } |
| 261 | |
| 262 | struct inode *logfs_read_meta_inode(struct super_block *sb, u64 ino) |
| 263 | { |
| 264 | struct inode *inode; |
| 265 | int err; |
| 266 | |
| 267 | inode = logfs_new_meta_inode(sb, ino); |
| 268 | if (IS_ERR(inode)) |
| 269 | return inode; |
| 270 | |
| 271 | err = logfs_read_inode(inode); |
| 272 | if (err) { |
Al Viro | 8e22c1a | 2010-06-07 12:22:31 -0400 | [diff] [blame] | 273 | iput(inode); |
Joern Engel | 5db53f3 | 2009-11-20 20:13:39 +0100 | [diff] [blame] | 274 | return ERR_PTR(err); |
| 275 | } |
| 276 | logfs_inode_setops(inode); |
| 277 | return inode; |
| 278 | } |
| 279 | |
Linus Torvalds | 66b8915 | 2010-03-06 13:18:03 -0800 | [diff] [blame] | 280 | static int logfs_write_inode(struct inode *inode, struct writeback_control *wbc) |
Joern Engel | 5db53f3 | 2009-11-20 20:13:39 +0100 | [diff] [blame] | 281 | { |
| 282 | int ret; |
| 283 | long flags = WF_LOCK; |
| 284 | |
| 285 | /* Can only happen if creat() failed. Safe to skip. */ |
| 286 | if (logfs_inode(inode)->li_flags & LOGFS_IF_STILLBORN) |
| 287 | return 0; |
| 288 | |
| 289 | ret = __logfs_write_inode(inode, flags); |
| 290 | LOGFS_BUG_ON(ret, inode->i_sb); |
| 291 | return ret; |
| 292 | } |
| 293 | |
Dave Chinner | f283c86 | 2011-03-22 22:23:39 +1100 | [diff] [blame] | 294 | /* called with inode->i_lock held */ |
Al Viro | 45321ac | 2010-06-07 13:43:19 -0400 | [diff] [blame] | 295 | static int logfs_drop_inode(struct inode *inode) |
Joern Engel | 5db53f3 | 2009-11-20 20:13:39 +0100 | [diff] [blame] | 296 | { |
| 297 | struct logfs_super *super = logfs_super(inode->i_sb); |
| 298 | struct logfs_inode *li = logfs_inode(inode); |
| 299 | |
| 300 | spin_lock(&logfs_inode_lock); |
| 301 | list_move(&li->li_freeing_list, &super->s_freeing_list); |
| 302 | spin_unlock(&logfs_inode_lock); |
Al Viro | 45321ac | 2010-06-07 13:43:19 -0400 | [diff] [blame] | 303 | return generic_drop_inode(inode); |
Joern Engel | 5db53f3 | 2009-11-20 20:13:39 +0100 | [diff] [blame] | 304 | } |
| 305 | |
| 306 | static void logfs_set_ino_generation(struct super_block *sb, |
| 307 | struct inode *inode) |
| 308 | { |
| 309 | struct logfs_super *super = logfs_super(sb); |
| 310 | u64 ino; |
| 311 | |
| 312 | mutex_lock(&super->s_journal_mutex); |
Joern Engel | ccc0197 | 2010-05-01 17:00:34 +0200 | [diff] [blame] | 313 | ino = logfs_seek_hole(super->s_master_inode, super->s_last_ino + 1); |
Joern Engel | 5db53f3 | 2009-11-20 20:13:39 +0100 | [diff] [blame] | 314 | super->s_last_ino = ino; |
| 315 | super->s_inos_till_wrap--; |
| 316 | if (super->s_inos_till_wrap < 0) { |
| 317 | super->s_last_ino = LOGFS_RESERVED_INOS; |
| 318 | super->s_generation++; |
| 319 | super->s_inos_till_wrap = INOS_PER_WRAP; |
| 320 | } |
| 321 | inode->i_ino = ino; |
| 322 | inode->i_generation = super->s_generation; |
| 323 | mutex_unlock(&super->s_journal_mutex); |
| 324 | } |
| 325 | |
Al Viro | 8817644 | 2011-07-26 03:13:21 -0400 | [diff] [blame] | 326 | struct inode *logfs_new_inode(struct inode *dir, umode_t mode) |
Joern Engel | 5db53f3 | 2009-11-20 20:13:39 +0100 | [diff] [blame] | 327 | { |
| 328 | struct super_block *sb = dir->i_sb; |
| 329 | struct inode *inode; |
| 330 | |
| 331 | inode = new_inode(sb); |
| 332 | if (!inode) |
| 333 | return ERR_PTR(-ENOMEM); |
| 334 | |
| 335 | logfs_init_inode(sb, inode); |
| 336 | |
| 337 | /* inherit parent flags */ |
| 338 | logfs_inode(inode)->li_flags |= |
| 339 | logfs_inode(dir)->li_flags & LOGFS_FL_INHERITED; |
| 340 | |
| 341 | inode->i_mode = mode; |
| 342 | logfs_set_ino_generation(sb, inode); |
| 343 | |
Al Viro | ab9a79b | 2010-05-15 04:02:54 -0400 | [diff] [blame] | 344 | inode_init_owner(inode, dir, mode); |
Joern Engel | 5db53f3 | 2009-11-20 20:13:39 +0100 | [diff] [blame] | 345 | logfs_inode_setops(inode); |
| 346 | insert_inode_hash(inode); |
| 347 | |
| 348 | return inode; |
| 349 | } |
| 350 | |
| 351 | static void logfs_init_once(void *_li) |
| 352 | { |
| 353 | struct logfs_inode *li = _li; |
| 354 | int i; |
| 355 | |
| 356 | li->li_flags = 0; |
| 357 | li->li_used_bytes = 0; |
| 358 | li->li_refcount = 1; |
| 359 | for (i = 0; i < LOGFS_EMBEDDED_FIELDS; i++) |
| 360 | li->li_data[i] = 0; |
| 361 | inode_init_once(&li->vfs_inode); |
| 362 | } |
| 363 | |
| 364 | static int logfs_sync_fs(struct super_block *sb, int wait) |
| 365 | { |
Joern Engel | c0c79c3 | 2010-05-05 22:33:36 +0200 | [diff] [blame] | 366 | logfs_write_anchor(sb); |
Joern Engel | 5db53f3 | 2009-11-20 20:13:39 +0100 | [diff] [blame] | 367 | return 0; |
| 368 | } |
| 369 | |
Al Viro | 8e22c1a | 2010-06-07 12:22:31 -0400 | [diff] [blame] | 370 | static void logfs_put_super(struct super_block *sb) |
| 371 | { |
| 372 | struct logfs_super *super = logfs_super(sb); |
| 373 | /* kill the meta-inodes */ |
| 374 | iput(super->s_master_inode); |
| 375 | iput(super->s_segfile_inode); |
| 376 | iput(super->s_mapping_inode); |
| 377 | } |
| 378 | |
Joern Engel | 5db53f3 | 2009-11-20 20:13:39 +0100 | [diff] [blame] | 379 | const struct super_operations logfs_super_operations = { |
| 380 | .alloc_inode = logfs_alloc_inode, |
Joern Engel | 5db53f3 | 2009-11-20 20:13:39 +0100 | [diff] [blame] | 381 | .destroy_inode = logfs_destroy_inode, |
Al Viro | 7da08fd | 2010-06-07 13:11:34 -0400 | [diff] [blame] | 382 | .evict_inode = logfs_evict_inode, |
Joern Engel | 5db53f3 | 2009-11-20 20:13:39 +0100 | [diff] [blame] | 383 | .drop_inode = logfs_drop_inode, |
Al Viro | 8e22c1a | 2010-06-07 12:22:31 -0400 | [diff] [blame] | 384 | .put_super = logfs_put_super, |
Joern Engel | 5db53f3 | 2009-11-20 20:13:39 +0100 | [diff] [blame] | 385 | .write_inode = logfs_write_inode, |
| 386 | .statfs = logfs_statfs, |
| 387 | .sync_fs = logfs_sync_fs, |
| 388 | }; |
| 389 | |
| 390 | int logfs_init_inode_cache(void) |
| 391 | { |
| 392 | logfs_inode_cache = kmem_cache_create("logfs_inode_cache", |
| 393 | sizeof(struct logfs_inode), 0, SLAB_RECLAIM_ACCOUNT, |
| 394 | logfs_init_once); |
| 395 | if (!logfs_inode_cache) |
| 396 | return -ENOMEM; |
| 397 | return 0; |
| 398 | } |
| 399 | |
| 400 | void logfs_destroy_inode_cache(void) |
| 401 | { |
| 402 | kmem_cache_destroy(logfs_inode_cache); |
| 403 | } |