git.oblomov.eu Git - linux-2.6/blob - fs/ocfs2/extent_map.c

   1 /* -*- mode: c; c-basic-offset: 8; -*-
   2  * vim: noexpandtab sw=8 ts=8 sts=0:
   3  *
   4  * extent_map.c
   5  *
   6  * Block/Cluster mapping functions
   7  *
   8  * Copyright (C) 2004 Oracle.  All rights reserved.
   9  *
  10  * This program is free software; you can redistribute it and/or
  11  * modify it under the terms of the GNU General Public
  12  * License, version 2,  as published by the Free Software Foundation.
  13  *
  14  * This program is distributed in the hope that it will be useful,
  15  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  16  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  17  * General Public License for more details.
  18  *
  19  * You should have received a copy of the GNU General Public
  20  * License along with this program; if not, write to the
  21  * Free Software Foundation, Inc., 59 Temple Place - Suite 330,
  22  * Boston, MA 021110-1307, USA.
  23  */
  24
  25 #include <linux/fs.h>
  26 #include <linux/init.h>
  27 #include <linux/types.h>
  28
  29 #define MLOG_MASK_PREFIX ML_EXTENT_MAP
  30 #include <cluster/masklog.h>
  31
  32 #include "ocfs2.h"
  33
  34 #include "alloc.h"
  35 #include "extent_map.h"
  36 #include "inode.h"
  37 #include "super.h"
  38
  39 #include "buffer_head_io.h"
  40
  41 /*
  42  * The extent caching implementation is intentionally trivial.
  43  *
  44  * We only cache a small number of extents stored directly on the
  45  * inode, so linear order operations are acceptable. If we ever want
  46  * to increase the size of the extent map, then these algorithms must
  47  * get smarter.
  48  */
  49
  50 void ocfs2_extent_map_init(struct inode *inode)
  51 {
  52         struct ocfs2_inode_info *oi = OCFS2_I(inode);
  53
  54         oi->ip_extent_map.em_num_items = 0;
  55         INIT_LIST_HEAD(&oi->ip_extent_map.em_list);
  56 }
  57
  58 static void __ocfs2_extent_map_lookup(struct ocfs2_extent_map *em,
  59                                       unsigned int cpos,
  60                                       struct ocfs2_extent_map_item **ret_emi)
  61 {
  62         unsigned int range;
  63         struct ocfs2_extent_map_item *emi;
  64
  65         *ret_emi = NULL;
  66
  67         list_for_each_entry(emi, &em->em_list, ei_list) {
  68                 range = emi->ei_cpos + emi->ei_clusters;
  69
  70                 if (cpos >= emi->ei_cpos && cpos < range) {
  71                         list_move(&emi->ei_list, &em->em_list);
  72
  73                         *ret_emi = emi;
  74                         break;
  75                 }
  76         }
  77 }
  78
  79 static int ocfs2_extent_map_lookup(struct inode *inode, unsigned int cpos,
  80                                    unsigned int *phys, unsigned int *len,
  81                                    unsigned int *flags)
  82 {
  83         unsigned int coff;
  84         struct ocfs2_inode_info *oi = OCFS2_I(inode);
  85         struct ocfs2_extent_map_item *emi;
  86
  87         spin_lock(&oi->ip_lock);
  88
  89         __ocfs2_extent_map_lookup(&oi->ip_extent_map, cpos, &emi);
  90         if (emi) {
  91                 coff = cpos - emi->ei_cpos;
  92                 *phys = emi->ei_phys + coff;
  93                 if (len)
  94                         *len = emi->ei_clusters - coff;
  95                 if (flags)
  96                         *flags = emi->ei_flags;
  97         }
  98
  99         spin_unlock(&oi->ip_lock);
 100
 101         if (emi == NULL)
 102                 return -ENOENT;
 103
 104         return 0;
 105 }
 106
 107 /*
 108  * Forget about all clusters equal to or greater than cpos.
 109  */
 110 void ocfs2_extent_map_trunc(struct inode *inode, unsigned int cpos)
 111 {
 112         struct ocfs2_extent_map_item *emi, *n;
 113         struct ocfs2_inode_info *oi = OCFS2_I(inode);
 114         struct ocfs2_extent_map *em = &oi->ip_extent_map;
 115         LIST_HEAD(tmp_list);
 116         unsigned int range;
 117
 118         spin_lock(&oi->ip_lock);
 119         list_for_each_entry_safe(emi, n, &em->em_list, ei_list) {
 120                 if (emi->ei_cpos >= cpos) {
 121                         /* Full truncate of this record. */
 122                         list_move(&emi->ei_list, &tmp_list);
 123                         BUG_ON(em->em_num_items == 0);
 124                         em->em_num_items--;
 125                         continue;
 126                 }
 127
 128                 range = emi->ei_cpos + emi->ei_clusters;
 129                 if (range > cpos) {
 130                         /* Partial truncate */
 131                         emi->ei_clusters = cpos - emi->ei_cpos;
 132                 }
 133         }
 134         spin_unlock(&oi->ip_lock);
 135
 136         list_for_each_entry_safe(emi, n, &tmp_list, ei_list) {
 137                 list_del(&emi->ei_list);
 138                 kfree(emi);
 139         }
 140 }
 141
 142 /*
 143  * Is any part of emi2 contained within emi1
 144  */
 145 static int ocfs2_ei_is_contained(struct ocfs2_extent_map_item *emi1,
 146                                  struct ocfs2_extent_map_item *emi2)
 147 {
 148         unsigned int range1, range2;
 149
 150         /*
 151          * Check if logical start of emi2 is inside emi1
 152          */
 153         range1 = emi1->ei_cpos + emi1->ei_clusters;
 154         if (emi2->ei_cpos >= emi1->ei_cpos && emi2->ei_cpos < range1)
 155                 return 1;
 156
 157         /*
 158          * Check if logical end of emi2 is inside emi1
 159          */
 160         range2 = emi2->ei_cpos + emi2->ei_clusters;
 161         if (range2 > emi1->ei_cpos && range2 <= range1)
 162                 return 1;
 163
 164         return 0;
 165 }
 166
 167 static void ocfs2_copy_emi_fields(struct ocfs2_extent_map_item *dest,
 168                                   struct ocfs2_extent_map_item *src)
 169 {
 170         dest->ei_cpos = src->ei_cpos;
 171         dest->ei_phys = src->ei_phys;
 172         dest->ei_clusters = src->ei_clusters;
 173         dest->ei_flags = src->ei_flags;
 174 }
 175
 176 /*
 177  * Try to merge emi with ins. Returns 1 if merge succeeds, zero
 178  * otherwise.
 179  */
 180 static int ocfs2_try_to_merge_extent_map(struct ocfs2_extent_map_item *emi,
 181                                          struct ocfs2_extent_map_item *ins)
 182 {
 183         /*
 184          * Handle contiguousness
 185          */
 186         if (ins->ei_phys == (emi->ei_phys + emi->ei_clusters) &&
 187             ins->ei_cpos == (emi->ei_cpos + emi->ei_clusters) &&
 188             ins->ei_flags == emi->ei_flags) {
 189                 emi->ei_clusters += ins->ei_clusters;
 190                 return 1;
 191         } else if ((ins->ei_phys + ins->ei_clusters) == emi->ei_phys &&
 192                    (ins->ei_cpos + ins->ei_clusters) == emi->ei_phys &&
 193                    ins->ei_flags == emi->ei_flags) {
 194                 emi->ei_phys = ins->ei_phys;
 195                 emi->ei_cpos = ins->ei_cpos;
 196                 emi->ei_clusters += ins->ei_clusters;
 197                 return 1;
 198         }
 199
 200         /*
 201          * Overlapping extents - this shouldn't happen unless we've
 202          * split an extent to change it's flags. That is exceedingly
 203          * rare, so there's no sense in trying to optimize it yet.
 204          */
 205         if (ocfs2_ei_is_contained(emi, ins) ||
 206             ocfs2_ei_is_contained(ins, emi)) {
 207                 ocfs2_copy_emi_fields(emi, ins);
 208                 return 1;
 209         }
 210
 211         /* No merge was possible. */
 212         return 0;
 213 }
 214
 215 /*
 216  * In order to reduce complexity on the caller, this insert function
 217  * is intentionally liberal in what it will accept.
 218  *
 219  * The only rule is that the truncate call *must* be used whenever
 220  * records have been deleted. This avoids inserting overlapping
 221  * records with different physical mappings.
 222  */
 223 void ocfs2_extent_map_insert_rec(struct inode *inode,
 224                                  struct ocfs2_extent_rec *rec)
 225 {
 226         struct ocfs2_inode_info *oi = OCFS2_I(inode);
 227         struct ocfs2_extent_map *em = &oi->ip_extent_map;
 228         struct ocfs2_extent_map_item *emi, *new_emi = NULL;
 229         struct ocfs2_extent_map_item ins;
 230
 231         ins.ei_cpos = le32_to_cpu(rec->e_cpos);
 232         ins.ei_phys = ocfs2_blocks_to_clusters(inode->i_sb,
 233                                                le64_to_cpu(rec->e_blkno));
 234         ins.ei_clusters = le16_to_cpu(rec->e_leaf_clusters);
 235         ins.ei_flags = rec->e_flags;
 236
 237 search:
 238         spin_lock(&oi->ip_lock);
 239
 240         list_for_each_entry(emi, &em->em_list, ei_list) {
 241                 if (ocfs2_try_to_merge_extent_map(emi, &ins)) {
 242                         list_move(&emi->ei_list, &em->em_list);
 243                         spin_unlock(&oi->ip_lock);
 244                         goto out;
 245                 }
 246         }
 247
 248         /*
 249          * No item could be merged.
 250          *
 251          * Either allocate and add a new item, or overwrite the last recently
 252          * inserted.
 253          */
 254
 255         if (em->em_num_items < OCFS2_MAX_EXTENT_MAP_ITEMS) {
 256                 if (new_emi == NULL) {
 257                         spin_unlock(&oi->ip_lock);
 258
 259                         new_emi = kmalloc(sizeof(*new_emi), GFP_NOFS);
 260                         if (new_emi == NULL)
 261                                 goto out;
 262
 263                         goto search;
 264                 }
 265
 266                 ocfs2_copy_emi_fields(new_emi, &ins);
 267                 list_add(&new_emi->ei_list, &em->em_list);
 268                 em->em_num_items++;
 269                 new_emi = NULL;
 270         } else {
 271                 BUG_ON(list_empty(&em->em_list) || em->em_num_items == 0);
 272                 emi = list_entry(em->em_list.prev,
 273                                  struct ocfs2_extent_map_item, ei_list);
 274                 list_move(&emi->ei_list, &em->em_list);
 275                 ocfs2_copy_emi_fields(emi, &ins);
 276         }
 277
 278         spin_unlock(&oi->ip_lock);
 279
 280 out:
 281         if (new_emi)
 282                 kfree(new_emi);
 283 }
 284
 285 /*
 286  * Return the 1st index within el which contains an extent start
 287  * larger than v_cluster.
 288  */
 289 static int ocfs2_search_for_hole_index(struct ocfs2_extent_list *el,
 290                                        u32 v_cluster)
 291 {
 292         int i;
 293         struct ocfs2_extent_rec *rec;
 294
 295         for(i = 0; i < le16_to_cpu(el->l_next_free_rec); i++) {
 296                 rec = &el->l_recs[i];
 297
 298                 if (v_cluster < le32_to_cpu(rec->e_cpos))
 299                         break;
 300         }
 301
 302         return i;
 303 }
 304
 305 /*
 306  * Figure out the size of a hole which starts at v_cluster within the given
 307  * extent list.
 308  *
 309  * If there is no more allocation past v_cluster, we return the maximum
 310  * cluster size minus v_cluster.
 311  *
 312  * If we have in-inode extents, then el points to the dinode list and
 313  * eb_bh is NULL. Otherwise, eb_bh should point to the extent block
 314  * containing el.
 315  */
 316 static int ocfs2_figure_hole_clusters(struct inode *inode,
 317                                       struct ocfs2_extent_list *el,
 318                                       struct buffer_head *eb_bh,
 319                                       u32 v_cluster,
 320                                       u32 *num_clusters)
 321 {
 322         int ret, i;
 323         struct buffer_head *next_eb_bh = NULL;
 324         struct ocfs2_extent_block *eb, *next_eb;
 325
 326         i = ocfs2_search_for_hole_index(el, v_cluster);
 327
 328         if (i == le16_to_cpu(el->l_next_free_rec) && eb_bh) {
 329                 eb = (struct ocfs2_extent_block *)eb_bh->b_data;
 330
 331                 /*
 332                  * Check the next leaf for any extents.
 333                  */
 334
 335                 if (le64_to_cpu(eb->h_next_leaf_blk) == 0ULL)
 336                         goto no_more_extents;
 337
 338                 ret = ocfs2_read_block(OCFS2_SB(inode->i_sb),
 339                                        le64_to_cpu(eb->h_next_leaf_blk),
 340                                        &next_eb_bh, OCFS2_BH_CACHED, inode);
 341                 if (ret) {
 342                         mlog_errno(ret);
 343                         goto out;
 344                 }
 345                 next_eb = (struct ocfs2_extent_block *)next_eb_bh->b_data;
 346
 347                 if (!OCFS2_IS_VALID_EXTENT_BLOCK(next_eb)) {
 348                         ret = -EROFS;
 349                         OCFS2_RO_ON_INVALID_EXTENT_BLOCK(inode->i_sb, next_eb);
 350                         goto out;
 351                 }
 352
 353                 el = &next_eb->h_list;
 354
 355                 i = ocfs2_search_for_hole_index(el, v_cluster);
 356         }
 357
 358 no_more_extents:
 359         if (i == le16_to_cpu(el->l_next_free_rec)) {
 360                 /*
 361                  * We're at the end of our existing allocation. Just
 362                  * return the maximum number of clusters we could
 363                  * possibly allocate.
 364                  */
 365                 *num_clusters = UINT_MAX - v_cluster;
 366         } else {
 367                 *num_clusters = le32_to_cpu(el->l_recs[i].e_cpos) - v_cluster;
 368         }
 369
 370         ret = 0;
 371 out:
 372         brelse(next_eb_bh);
 373         return ret;
 374 }
 375
 376 int ocfs2_get_clusters(struct inode *inode, u32 v_cluster,
 377                        u32 *p_cluster, u32 *num_clusters,
 378                        unsigned int *extent_flags)
 379 {
 380         int ret, i;
 381         unsigned int flags = 0;
 382         struct buffer_head *di_bh = NULL;
 383         struct buffer_head *eb_bh = NULL;
 384         struct ocfs2_dinode *di;
 385         struct ocfs2_extent_block *eb;
 386         struct ocfs2_extent_list *el;
 387         struct ocfs2_extent_rec *rec;
 388         u32 coff;
 389
 390         ret = ocfs2_extent_map_lookup(inode, v_cluster, p_cluster,
 391                                       num_clusters, extent_flags);
 392         if (ret == 0)
 393                 goto out;
 394
 395         ret = ocfs2_read_block(OCFS2_SB(inode->i_sb), OCFS2_I(inode)->ip_blkno,
 396                                &di_bh, OCFS2_BH_CACHED, inode);
 397         if (ret) {
 398                 mlog_errno(ret);
 399                 goto out;
 400         }
 401
 402         di = (struct ocfs2_dinode *) di_bh->b_data;
 403         el = &di->id2.i_list;
 404
 405         if (el->l_tree_depth) {
 406                 ret = ocfs2_find_leaf(inode, el, v_cluster, &eb_bh);
 407                 if (ret) {
 408                         mlog_errno(ret);
 409                         goto out;
 410                 }
 411
 412                 eb = (struct ocfs2_extent_block *) eb_bh->b_data;
 413                 el = &eb->h_list;
 414
 415                 if (el->l_tree_depth) {
 416                         ocfs2_error(inode->i_sb,
 417                                     "Inode %lu has non zero tree depth in "
 418                                     "leaf block %llu\n", inode->i_ino,
 419                                     (unsigned long long)eb_bh->b_blocknr);
 420                         ret = -EROFS;
 421                         goto out;
 422                 }
 423         }
 424
 425         i = ocfs2_search_extent_list(el, v_cluster);
 426         if (i == -1) {
 427                 /*
 428                  * A hole was found. Return some canned values that
 429                  * callers can key on. If asked for, num_clusters will
 430                  * be populated with the size of the hole.
 431                  */
 432                 *p_cluster = 0;
 433                 if (num_clusters) {
 434                         ret = ocfs2_figure_hole_clusters(inode, el, eb_bh,
 435                                                          v_cluster,
 436                                                          num_clusters);
 437                         if (ret) {
 438                                 mlog_errno(ret);
 439                                 goto out;
 440                         }
 441                 }
 442         } else {
 443                 rec = &el->l_recs[i];
 444
 445                 BUG_ON(v_cluster < le32_to_cpu(rec->e_cpos));
 446
 447                 if (!rec->e_blkno) {
 448                         ocfs2_error(inode->i_sb, "Inode %lu has bad extent "
 449                                     "record (%u, %u, 0)", inode->i_ino,
 450                                     le32_to_cpu(rec->e_cpos),
 451                                     ocfs2_rec_clusters(el, rec));
 452                         ret = -EROFS;
 453                         goto out;
 454                 }
 455
 456                 coff = v_cluster - le32_to_cpu(rec->e_cpos);
 457
 458                 *p_cluster = ocfs2_blocks_to_clusters(inode->i_sb,
 459                                                     le64_to_cpu(rec->e_blkno));
 460                 *p_cluster = *p_cluster + coff;
 461
 462                 if (num_clusters)
 463                         *num_clusters = ocfs2_rec_clusters(el, rec) - coff;
 464
 465                 flags = rec->e_flags;
 466
 467                 ocfs2_extent_map_insert_rec(inode, rec);
 468         }
 469
 470         if (extent_flags)
 471                 *extent_flags = flags;
 472
 473 out:
 474         brelse(di_bh);
 475         brelse(eb_bh);
 476         return ret;
 477 }
 478
 479 /*
 480  * This expects alloc_sem to be held. The allocation cannot change at
 481  * all while the map is in the process of being updated.
 482  */
 483 int ocfs2_extent_map_get_blocks(struct inode *inode, u64 v_blkno, u64 *p_blkno,
 484                                 u64 *ret_count, unsigned int *extent_flags)
 485 {
 486         int ret;
 487         int bpc = ocfs2_clusters_to_blocks(inode->i_sb, 1);
 488         u32 cpos, num_clusters, p_cluster;
 489         u64 boff = 0;
 490
 491         cpos = ocfs2_blocks_to_clusters(inode->i_sb, v_blkno);
 492
 493         ret = ocfs2_get_clusters(inode, cpos, &p_cluster, &num_clusters,
 494                                  extent_flags);
 495         if (ret) {
 496                 mlog_errno(ret);
 497                 goto out;
 498         }
 499
 500         /*
 501          * p_cluster == 0 indicates a hole.
 502          */
 503         if (p_cluster) {
 504                 boff = ocfs2_clusters_to_blocks(inode->i_sb, p_cluster);
 505                 boff += (v_blkno & (u64)(bpc - 1));
 506         }
 507
 508         *p_blkno = boff;
 509
 510         if (ret_count) {
 511                 *ret_count = ocfs2_clusters_to_blocks(inode->i_sb, num_clusters);
 512                 *ret_count -= v_blkno & (u64)(bpc - 1);
 513         }
 514
 515 out:
 516         return ret;
 517 }