LCOV - code coverage report
Current view: top level - fs/jbd2 - revoke.c (source / functions) Hit Total Coverage
Test: Real Lines: 150 188 79.8 %
Date: 2020-10-17 15:46:43 Functions: 0 21 0.0 %
Legend: Neither, QEMU, Real, Both Branches: 0 0 -

           Branch data     Line data    Source code
       1                 :            : // SPDX-License-Identifier: GPL-2.0+
       2                 :            : /*
       3                 :            :  * linux/fs/jbd2/revoke.c
       4                 :            :  *
       5                 :            :  * Written by Stephen C. Tweedie <sct@redhat.com>, 2000
       6                 :            :  *
       7                 :            :  * Copyright 2000 Red Hat corp --- All Rights Reserved
       8                 :            :  *
       9                 :            :  * Journal revoke routines for the generic filesystem journaling code;
      10                 :            :  * part of the ext2fs journaling system.
      11                 :            :  *
      12                 :            :  * Revoke is the mechanism used to prevent old log records for deleted
      13                 :            :  * metadata from being replayed on top of newer data using the same
      14                 :            :  * blocks.  The revoke mechanism is used in two separate places:
      15                 :            :  *
      16                 :            :  * + Commit: during commit we write the entire list of the current
      17                 :            :  *   transaction's revoked blocks to the journal
      18                 :            :  *
      19                 :            :  * + Recovery: during recovery we record the transaction ID of all
      20                 :            :  *   revoked blocks.  If there are multiple revoke records in the log
      21                 :            :  *   for a single block, only the last one counts, and if there is a log
      22                 :            :  *   entry for a block beyond the last revoke, then that log entry still
      23                 :            :  *   gets replayed.
      24                 :            :  *
      25                 :            :  * We can get interactions between revokes and new log data within a
      26                 :            :  * single transaction:
      27                 :            :  *
      28                 :            :  * Block is revoked and then journaled:
      29                 :            :  *   The desired end result is the journaling of the new block, so we
      30                 :            :  *   cancel the revoke before the transaction commits.
      31                 :            :  *
      32                 :            :  * Block is journaled and then revoked:
      33                 :            :  *   The revoke must take precedence over the write of the block, so we
      34                 :            :  *   need either to cancel the journal entry or to write the revoke
      35                 :            :  *   later in the log than the log block.  In this case, we choose the
      36                 :            :  *   latter: journaling a block cancels any revoke record for that block
      37                 :            :  *   in the current transaction, so any revoke for that block in the
      38                 :            :  *   transaction must have happened after the block was journaled and so
      39                 :            :  *   the revoke must take precedence.
      40                 :            :  *
      41                 :            :  * Block is revoked and then written as data:
      42                 :            :  *   The data write is allowed to succeed, but the revoke is _not_
      43                 :            :  *   cancelled.  We still need to prevent old log records from
      44                 :            :  *   overwriting the new data.  We don't even need to clear the revoke
      45                 :            :  *   bit here.
      46                 :            :  *
      47                 :            :  * We cache revoke status of a buffer in the current transaction in b_states
      48                 :            :  * bits.  As the name says, revokevalid flag indicates that the cached revoke
      49                 :            :  * status of a buffer is valid and we can rely on the cached status.
      50                 :            :  *
      51                 :            :  * Revoke information on buffers is a tri-state value:
      52                 :            :  *
      53                 :            :  * RevokeValid clear:   no cached revoke status, need to look it up
      54                 :            :  * RevokeValid set, Revoked clear:
      55                 :            :  *                      buffer has not been revoked, and cancel_revoke
      56                 :            :  *                      need do nothing.
      57                 :            :  * RevokeValid set, Revoked set:
      58                 :            :  *                      buffer has been revoked.
      59                 :            :  *
      60                 :            :  * Locking rules:
      61                 :            :  * We keep two hash tables of revoke records. One hashtable belongs to the
      62                 :            :  * running transaction (is pointed to by journal->j_revoke), the other one
      63                 :            :  * belongs to the committing transaction. Accesses to the second hash table
      64                 :            :  * happen only from the kjournald and no other thread touches this table.  Also
      65                 :            :  * journal_switch_revoke_table() which switches which hashtable belongs to the
      66                 :            :  * running and which to the committing transaction is called only from
      67                 :            :  * kjournald. Therefore we need no locks when accessing the hashtable belonging
      68                 :            :  * to the committing transaction.
      69                 :            :  *
      70                 :            :  * All users operating on the hash table belonging to the running transaction
      71                 :            :  * have a handle to the transaction. Therefore they are safe from kjournald
      72                 :            :  * switching hash tables under them. For operations on the lists of entries in
      73                 :            :  * the hash table j_revoke_lock is used.
      74                 :            :  *
      75                 :            :  * Finally, also replay code uses the hash tables but at this moment no one else
      76                 :            :  * can touch them (filesystem isn't mounted yet) and hence no locking is
      77                 :            :  * needed.
      78                 :            :  */
      79                 :            : 
      80                 :            : #ifndef __KERNEL__
      81                 :            : #include "jfs_user.h"
      82                 :            : #else
      83                 :            : #include <linux/time.h>
      84                 :            : #include <linux/fs.h>
      85                 :            : #include <linux/jbd2.h>
      86                 :            : #include <linux/errno.h>
      87                 :            : #include <linux/slab.h>
      88                 :            : #include <linux/list.h>
      89                 :            : #include <linux/init.h>
      90                 :            : #include <linux/bio.h>
      91                 :            : #include <linux/log2.h>
      92                 :            : #include <linux/hash.h>
      93                 :            : #endif
      94                 :            : 
      95                 :            : static struct kmem_cache *jbd2_revoke_record_cache;
      96                 :            : static struct kmem_cache *jbd2_revoke_table_cache;
      97                 :            : 
      98                 :            : /* Each revoke record represents one single revoked block.  During
      99                 :            :    journal replay, this involves recording the transaction ID of the
     100                 :            :    last transaction to revoke this block. */
     101                 :            : 
     102                 :            : struct jbd2_revoke_record_s
     103                 :            : {
     104                 :            :         struct list_head  hash;
     105                 :            :         tid_t             sequence;     /* Used for recovery only */
     106                 :            :         unsigned long long        blocknr;
     107                 :            : };
     108                 :            : 
     109                 :            : 
     110                 :            : /* The revoke table is just a simple hash table of revoke records. */
     111                 :            : struct jbd2_revoke_table_s
     112                 :            : {
     113                 :            :         /* It is conceivable that we might want a larger hash table
     114                 :            :          * for recovery.  Must be a power of two. */
     115                 :            :         int               hash_size;
     116                 :            :         int               hash_shift;
     117                 :            :         struct list_head *hash_table;
     118                 :            : };
     119                 :            : 
     120                 :            : 
     121                 :            : #ifdef __KERNEL__
     122                 :            : static void write_one_revoke_record(transaction_t *,
     123                 :            :                                     struct list_head *,
     124                 :            :                                     struct buffer_head **, int *,
     125                 :            :                                     struct jbd2_revoke_record_s *);
     126                 :            : static void flush_descriptor(journal_t *, struct buffer_head *, int);
     127                 :            : #endif
     128                 :            : 
     129                 :            : /* Utility functions to maintain the revoke table */
     130                 :            : 
     131                 :          3 : static inline int hash(journal_t *journal, unsigned long long block)
     132                 :            : {
     133                 :          3 :         return hash_64(block, journal->j_revoke->hash_shift);
     134                 :            : }
     135                 :            : 
     136                 :          3 : static int insert_revoke_hash(journal_t *journal, unsigned long long blocknr,
     137                 :            :                               tid_t seq)
     138                 :            : {
     139                 :            :         struct list_head *hash_list;
     140                 :            :         struct jbd2_revoke_record_s *record;
     141                 :            :         gfp_t gfp_mask = GFP_NOFS;
     142                 :            : 
     143                 :            :         if (journal_oom_retry)
     144                 :            :                 gfp_mask |= __GFP_NOFAIL;
     145                 :          3 :         record = kmem_cache_alloc(jbd2_revoke_record_cache, gfp_mask);
     146                 :          3 :         if (!record)
     147                 :            :                 return -ENOMEM;
     148                 :            : 
     149                 :          3 :         record->sequence = seq;
     150                 :          3 :         record->blocknr = blocknr;
     151                 :          3 :         hash_list = &journal->j_revoke->hash_table[hash(journal, blocknr)];
     152                 :            :         spin_lock(&journal->j_revoke_lock);
     153                 :          3 :         list_add(&record->hash, hash_list);
     154                 :            :         spin_unlock(&journal->j_revoke_lock);
     155                 :          3 :         return 0;
     156                 :            : }
     157                 :            : 
     158                 :            : /* Find a revoke record in the journal's hash table. */
     159                 :            : 
     160                 :          3 : static struct jbd2_revoke_record_s *find_revoke_record(journal_t *journal,
     161                 :            :                                                       unsigned long long blocknr)
     162                 :            : {
     163                 :            :         struct list_head *hash_list;
     164                 :            :         struct jbd2_revoke_record_s *record;
     165                 :            : 
     166                 :          3 :         hash_list = &journal->j_revoke->hash_table[hash(journal, blocknr)];
     167                 :            : 
     168                 :            :         spin_lock(&journal->j_revoke_lock);
     169                 :          3 :         record = (struct jbd2_revoke_record_s *) hash_list->next;
     170                 :          3 :         while (&(record->hash) != hash_list) {
     171                 :          3 :                 if (record->blocknr == blocknr) {
     172                 :            :                         spin_unlock(&journal->j_revoke_lock);
     173                 :          1 :                         return record;
     174                 :            :                 }
     175                 :          3 :                 record = (struct jbd2_revoke_record_s *) record->hash.next;
     176                 :            :         }
     177                 :            :         spin_unlock(&journal->j_revoke_lock);
     178                 :          3 :         return NULL;
     179                 :            : }
     180                 :            : 
     181                 :          0 : void jbd2_journal_destroy_revoke_record_cache(void)
     182                 :            : {
     183                 :          0 :         kmem_cache_destroy(jbd2_revoke_record_cache);
     184                 :          0 :         jbd2_revoke_record_cache = NULL;
     185                 :          0 : }
     186                 :            : 
     187                 :          0 : void jbd2_journal_destroy_revoke_table_cache(void)
     188                 :            : {
     189                 :          0 :         kmem_cache_destroy(jbd2_revoke_table_cache);
     190                 :          0 :         jbd2_revoke_table_cache = NULL;
     191                 :          0 : }
     192                 :            : 
     193                 :          3 : int __init jbd2_journal_init_revoke_record_cache(void)
     194                 :            : {
     195                 :          3 :         J_ASSERT(!jbd2_revoke_record_cache);
     196                 :          3 :         jbd2_revoke_record_cache = KMEM_CACHE(jbd2_revoke_record_s,
     197                 :            :                                         SLAB_HWCACHE_ALIGN|SLAB_TEMPORARY);
     198                 :            : 
     199                 :          3 :         if (!jbd2_revoke_record_cache) {
     200                 :          0 :                 pr_emerg("JBD2: failed to create revoke_record cache\n");
     201                 :          0 :                 return -ENOMEM;
     202                 :            :         }
     203                 :            :         return 0;
     204                 :            : }
     205                 :            : 
     206                 :          3 : int __init jbd2_journal_init_revoke_table_cache(void)
     207                 :            : {
     208                 :          3 :         J_ASSERT(!jbd2_revoke_table_cache);
     209                 :          3 :         jbd2_revoke_table_cache = KMEM_CACHE(jbd2_revoke_table_s,
     210                 :            :                                              SLAB_TEMPORARY);
     211                 :          3 :         if (!jbd2_revoke_table_cache) {
     212                 :          0 :                 pr_emerg("JBD2: failed to create revoke_table cache\n");
     213                 :          0 :                 return -ENOMEM;
     214                 :            :         }
     215                 :            :         return 0;
     216                 :            : }
     217                 :            : 
     218                 :          3 : static struct jbd2_revoke_table_s *jbd2_journal_init_revoke_table(int hash_size)
     219                 :            : {
     220                 :            :         int shift = 0;
     221                 :            :         int tmp = hash_size;
     222                 :            :         struct jbd2_revoke_table_s *table;
     223                 :            : 
     224                 :          3 :         table = kmem_cache_alloc(jbd2_revoke_table_cache, GFP_KERNEL);
     225                 :          3 :         if (!table)
     226                 :            :                 goto out;
     227                 :            : 
     228                 :          3 :         while((tmp >>= 1UL) != 0UL)
     229                 :          3 :                 shift++;
     230                 :            : 
     231                 :          3 :         table->hash_size = hash_size;
     232                 :          3 :         table->hash_shift = shift;
     233                 :          3 :         table->hash_table =
     234                 :          3 :                 kmalloc_array(hash_size, sizeof(struct list_head), GFP_KERNEL);
     235                 :          3 :         if (!table->hash_table) {
     236                 :          0 :                 kmem_cache_free(jbd2_revoke_table_cache, table);
     237                 :            :                 table = NULL;
     238                 :          0 :                 goto out;
     239                 :            :         }
     240                 :            : 
     241                 :          3 :         for (tmp = 0; tmp < hash_size; tmp++)
     242                 :          3 :                 INIT_LIST_HEAD(&table->hash_table[tmp]);
     243                 :            : 
     244                 :            : out:
     245                 :          3 :         return table;
     246                 :            : }
     247                 :            : 
     248                 :          0 : static void jbd2_journal_destroy_revoke_table(struct jbd2_revoke_table_s *table)
     249                 :            : {
     250                 :            :         int i;
     251                 :            :         struct list_head *hash_list;
     252                 :            : 
     253                 :          0 :         for (i = 0; i < table->hash_size; i++) {
     254                 :          0 :                 hash_list = &table->hash_table[i];
     255                 :          0 :                 J_ASSERT(list_empty(hash_list));
     256                 :            :         }
     257                 :            : 
     258                 :          0 :         kfree(table->hash_table);
     259                 :          0 :         kmem_cache_free(jbd2_revoke_table_cache, table);
     260                 :          0 : }
     261                 :            : 
     262                 :            : /* Initialise the revoke table for a given journal to a given size. */
     263                 :          3 : int jbd2_journal_init_revoke(journal_t *journal, int hash_size)
     264                 :            : {
     265                 :          3 :         J_ASSERT(journal->j_revoke_table[0] == NULL);
     266                 :          3 :         J_ASSERT(is_power_of_2(hash_size));
     267                 :            : 
     268                 :          3 :         journal->j_revoke_table[0] = jbd2_journal_init_revoke_table(hash_size);
     269                 :          3 :         if (!journal->j_revoke_table[0])
     270                 :            :                 goto fail0;
     271                 :            : 
     272                 :          3 :         journal->j_revoke_table[1] = jbd2_journal_init_revoke_table(hash_size);
     273                 :          3 :         if (!journal->j_revoke_table[1])
     274                 :            :                 goto fail1;
     275                 :            : 
     276                 :          3 :         journal->j_revoke = journal->j_revoke_table[1];
     277                 :            : 
     278                 :          3 :         spin_lock_init(&journal->j_revoke_lock);
     279                 :            : 
     280                 :          3 :         return 0;
     281                 :            : 
     282                 :            : fail1:
     283                 :          0 :         jbd2_journal_destroy_revoke_table(journal->j_revoke_table[0]);
     284                 :          0 :         journal->j_revoke_table[0] = NULL;
     285                 :            : fail0:
     286                 :            :         return -ENOMEM;
     287                 :            : }
     288                 :            : 
     289                 :            : /* Destroy a journal's revoke table.  The table must already be empty! */
     290                 :          0 : void jbd2_journal_destroy_revoke(journal_t *journal)
     291                 :            : {
     292                 :          0 :         journal->j_revoke = NULL;
     293                 :          0 :         if (journal->j_revoke_table[0])
     294                 :          0 :                 jbd2_journal_destroy_revoke_table(journal->j_revoke_table[0]);
     295                 :          0 :         if (journal->j_revoke_table[1])
     296                 :          0 :                 jbd2_journal_destroy_revoke_table(journal->j_revoke_table[1]);
     297                 :          0 : }
     298                 :            : 
     299                 :            : 
     300                 :            : #ifdef __KERNEL__
     301                 :            : 
     302                 :            : /*
     303                 :            :  * jbd2_journal_revoke: revoke a given buffer_head from the journal.  This
     304                 :            :  * prevents the block from being replayed during recovery if we take a
     305                 :            :  * crash after this current transaction commits.  Any subsequent
     306                 :            :  * metadata writes of the buffer in this transaction cancel the
     307                 :            :  * revoke.
     308                 :            :  *
     309                 :            :  * Note that this call may block --- it is up to the caller to make
     310                 :            :  * sure that there are no further calls to journal_write_metadata
     311                 :            :  * before the revoke is complete.  In ext3, this implies calling the
     312                 :            :  * revoke before clearing the block bitmap when we are deleting
     313                 :            :  * metadata.
     314                 :            :  *
     315                 :            :  * Revoke performs a jbd2_journal_forget on any buffer_head passed in as a
     316                 :            :  * parameter, but does _not_ forget the buffer_head if the bh was only
     317                 :            :  * found implicitly.
     318                 :            :  *
     319                 :            :  * bh_in may not be a journalled buffer - it may have come off
     320                 :            :  * the hash tables without an attached journal_head.
     321                 :            :  *
     322                 :            :  * If bh_in is non-zero, jbd2_journal_revoke() will decrement its b_count
     323                 :            :  * by one.
     324                 :            :  */
     325                 :            : 
     326                 :          3 : int jbd2_journal_revoke(handle_t *handle, unsigned long long blocknr,
     327                 :            :                    struct buffer_head *bh_in)
     328                 :            : {
     329                 :            :         struct buffer_head *bh = NULL;
     330                 :            :         journal_t *journal;
     331                 :            :         struct block_device *bdev;
     332                 :            :         int err;
     333                 :            : 
     334                 :          3 :         might_sleep();
     335                 :            :         if (bh_in)
     336                 :            :                 BUFFER_TRACE(bh_in, "enter");
     337                 :            : 
     338                 :          3 :         journal = handle->h_transaction->t_journal;
     339                 :          3 :         if (!jbd2_journal_set_features(journal, 0, 0, JBD2_FEATURE_INCOMPAT_REVOKE)){
     340                 :          0 :                 J_ASSERT (!"Cannot set revoke feature!");
     341                 :            :                 return -EINVAL;
     342                 :            :         }
     343                 :            : 
     344                 :          3 :         bdev = journal->j_fs_dev;
     345                 :            :         bh = bh_in;
     346                 :            : 
     347                 :          3 :         if (!bh) {
     348                 :          0 :                 bh = __find_get_block(bdev, blocknr, journal->j_blocksize);
     349                 :            :                 if (bh)
     350                 :            :                         BUFFER_TRACE(bh, "found on hash");
     351                 :            :         }
     352                 :            : #ifdef JBD2_EXPENSIVE_CHECKING
     353                 :            :         else {
     354                 :            :                 struct buffer_head *bh2;
     355                 :            : 
     356                 :            :                 /* If there is a different buffer_head lying around in
     357                 :            :                  * memory anywhere... */
     358                 :            :                 bh2 = __find_get_block(bdev, blocknr, journal->j_blocksize);
     359                 :            :                 if (bh2) {
     360                 :            :                         /* ... and it has RevokeValid status... */
     361                 :            :                         if (bh2 != bh && buffer_revokevalid(bh2))
     362                 :            :                                 /* ...then it better be revoked too,
     363                 :            :                                  * since it's illegal to create a revoke
     364                 :            :                                  * record against a buffer_head which is
     365                 :            :                                  * not marked revoked --- that would
     366                 :            :                                  * risk missing a subsequent revoke
     367                 :            :                                  * cancel. */
     368                 :            :                                 J_ASSERT_BH(bh2, buffer_revoked(bh2));
     369                 :            :                         put_bh(bh2);
     370                 :            :                 }
     371                 :            :         }
     372                 :            : #endif
     373                 :            : 
     374                 :            :         /* We really ought not ever to revoke twice in a row without
     375                 :            :            first having the revoke cancelled: it's illegal to free a
     376                 :            :            block twice without allocating it in between! */
     377                 :          3 :         if (bh) {
     378                 :          3 :                 if (!J_EXPECT_BH(bh, !buffer_revoked(bh),
     379                 :            :                                  "inconsistent data on disk")) {
     380                 :          0 :                         if (!bh_in)
     381                 :            :                                 brelse(bh);
     382                 :            :                         return -EIO;
     383                 :            :                 }
     384                 :            :                 set_buffer_revoked(bh);
     385                 :            :                 set_buffer_revokevalid(bh);
     386                 :          3 :                 if (bh_in) {
     387                 :            :                         BUFFER_TRACE(bh_in, "call jbd2_journal_forget");
     388                 :          3 :                         jbd2_journal_forget(handle, bh_in);
     389                 :            :                 } else {
     390                 :            :                         BUFFER_TRACE(bh, "call brelse");
     391                 :          0 :                         __brelse(bh);
     392                 :            :                 }
     393                 :            :         }
     394                 :            : 
     395                 :            :         jbd_debug(2, "insert revoke for block %llu, bh_in=%p\n",blocknr, bh_in);
     396                 :          3 :         err = insert_revoke_hash(journal, blocknr,
     397                 :          3 :                                 handle->h_transaction->t_tid);
     398                 :            :         BUFFER_TRACE(bh_in, "exit");
     399                 :          3 :         return err;
     400                 :            : }
     401                 :            : 
     402                 :            : /*
     403                 :            :  * Cancel an outstanding revoke.  For use only internally by the
     404                 :            :  * journaling code (called from jbd2_journal_get_write_access).
     405                 :            :  *
     406                 :            :  * We trust buffer_revoked() on the buffer if the buffer is already
     407                 :            :  * being journaled: if there is no revoke pending on the buffer, then we
     408                 :            :  * don't do anything here.
     409                 :            :  *
     410                 :            :  * This would break if it were possible for a buffer to be revoked and
     411                 :            :  * discarded, and then reallocated within the same transaction.  In such
     412                 :            :  * a case we would have lost the revoked bit, but when we arrived here
     413                 :            :  * the second time we would still have a pending revoke to cancel.  So,
     414                 :            :  * do not trust the Revoked bit on buffers unless RevokeValid is also
     415                 :            :  * set.
     416                 :            :  */
     417                 :          3 : int jbd2_journal_cancel_revoke(handle_t *handle, struct journal_head *jh)
     418                 :            : {
     419                 :            :         struct jbd2_revoke_record_s *record;
     420                 :          3 :         journal_t *journal = handle->h_transaction->t_journal;
     421                 :            :         int need_cancel;
     422                 :            :         int did_revoke = 0;     /* akpm: debug */
     423                 :            :         struct buffer_head *bh = jh2bh(jh);
     424                 :            : 
     425                 :            :         jbd_debug(4, "journal_head %p, cancelling revoke\n", jh);
     426                 :            : 
     427                 :            :         /* Is the existing Revoke bit valid?  If so, we trust it, and
     428                 :            :          * only perform the full cancel if the revoke bit is set.  If
     429                 :            :          * not, we can't trust the revoke bit, and we need to do the
     430                 :            :          * full search for a revoke record. */
     431                 :          3 :         if (test_set_buffer_revokevalid(bh)) {
     432                 :            :                 need_cancel = test_clear_buffer_revoked(bh);
     433                 :            :         } else {
     434                 :            :                 need_cancel = 1;
     435                 :            :                 clear_buffer_revoked(bh);
     436                 :            :         }
     437                 :            : 
     438                 :          3 :         if (need_cancel) {
     439                 :          3 :                 record = find_revoke_record(journal, bh->b_blocknr);
     440                 :          3 :                 if (record) {
     441                 :            :                         jbd_debug(4, "cancelled existing revoke on "
     442                 :            :                                   "blocknr %llu\n", (unsigned long long)bh->b_blocknr);
     443                 :            :                         spin_lock(&journal->j_revoke_lock);
     444                 :            :                         list_del(&record->hash);
     445                 :            :                         spin_unlock(&journal->j_revoke_lock);
     446                 :          0 :                         kmem_cache_free(jbd2_revoke_record_cache, record);
     447                 :            :                         did_revoke = 1;
     448                 :            :                 }
     449                 :            :         }
     450                 :            : 
     451                 :            : #ifdef JBD2_EXPENSIVE_CHECKING
     452                 :            :         /* There better not be one left behind by now! */
     453                 :            :         record = find_revoke_record(journal, bh->b_blocknr);
     454                 :            :         J_ASSERT_JH(jh, record == NULL);
     455                 :            : #endif
     456                 :            : 
     457                 :            :         /* Finally, have we just cleared revoke on an unhashed
     458                 :            :          * buffer_head?  If so, we'd better make sure we clear the
     459                 :            :          * revoked status on any hashed alias too, otherwise the revoke
     460                 :            :          * state machine will get very upset later on. */
     461                 :          3 :         if (need_cancel) {
     462                 :            :                 struct buffer_head *bh2;
     463                 :          3 :                 bh2 = __find_get_block(bh->b_bdev, bh->b_blocknr, bh->b_size);
     464                 :          3 :                 if (bh2) {
     465                 :          3 :                         if (bh2 != bh)
     466                 :            :                                 clear_buffer_revoked(bh2);
     467                 :          3 :                         __brelse(bh2);
     468                 :            :                 }
     469                 :            :         }
     470                 :          3 :         return did_revoke;
     471                 :            : }
     472                 :            : 
     473                 :            : /*
     474                 :            :  * journal_clear_revoked_flag clears revoked flag of buffers in
     475                 :            :  * revoke table to reflect there is no revoked buffers in the next
     476                 :            :  * transaction which is going to be started.
     477                 :            :  */
     478                 :          3 : void jbd2_clear_buffer_revoked_flags(journal_t *journal)
     479                 :            : {
     480                 :          3 :         struct jbd2_revoke_table_s *revoke = journal->j_revoke;
     481                 :            :         int i = 0;
     482                 :            : 
     483                 :          3 :         for (i = 0; i < revoke->hash_size; i++) {
     484                 :            :                 struct list_head *hash_list;
     485                 :            :                 struct list_head *list_entry;
     486                 :          3 :                 hash_list = &revoke->hash_table[i];
     487                 :            : 
     488                 :          3 :                 list_for_each(list_entry, hash_list) {
     489                 :            :                         struct jbd2_revoke_record_s *record;
     490                 :            :                         struct buffer_head *bh;
     491                 :            :                         record = (struct jbd2_revoke_record_s *)list_entry;
     492                 :          3 :                         bh = __find_get_block(journal->j_fs_dev,
     493                 :            :                                               record->blocknr,
     494                 :          3 :                                               journal->j_blocksize);
     495                 :          3 :                         if (bh) {
     496                 :            :                                 clear_buffer_revoked(bh);
     497                 :          3 :                                 __brelse(bh);
     498                 :            :                         }
     499                 :            :                 }
     500                 :            :         }
     501                 :          3 : }
     502                 :            : 
     503                 :            : /* journal_switch_revoke table select j_revoke for next transaction
     504                 :            :  * we do not want to suspend any processing until all revokes are
     505                 :            :  * written -bzzz
     506                 :            :  */
     507                 :          3 : void jbd2_journal_switch_revoke_table(journal_t *journal)
     508                 :            : {
     509                 :            :         int i;
     510                 :            : 
     511                 :          3 :         if (journal->j_revoke == journal->j_revoke_table[0])
     512                 :          3 :                 journal->j_revoke = journal->j_revoke_table[1];
     513                 :            :         else
     514                 :          3 :                 journal->j_revoke = journal->j_revoke_table[0];
     515                 :            : 
     516                 :          3 :         for (i = 0; i < journal->j_revoke->hash_size; i++)
     517                 :          3 :                 INIT_LIST_HEAD(&journal->j_revoke->hash_table[i]);
     518                 :          3 : }
     519                 :            : 
     520                 :            : /*
     521                 :            :  * Write revoke records to the journal for all entries in the current
     522                 :            :  * revoke hash, deleting the entries as we go.
     523                 :            :  */
     524                 :          3 : void jbd2_journal_write_revoke_records(transaction_t *transaction,
     525                 :            :                                        struct list_head *log_bufs)
     526                 :            : {
     527                 :          3 :         journal_t *journal = transaction->t_journal;
     528                 :            :         struct buffer_head *descriptor;
     529                 :            :         struct jbd2_revoke_record_s *record;
     530                 :            :         struct jbd2_revoke_table_s *revoke;
     531                 :            :         struct list_head *hash_list;
     532                 :            :         int i, offset, count;
     533                 :            : 
     534                 :          3 :         descriptor = NULL;
     535                 :          3 :         offset = 0;
     536                 :            :         count = 0;
     537                 :            : 
     538                 :            :         /* select revoke table for committing transaction */
     539                 :          3 :         revoke = journal->j_revoke == journal->j_revoke_table[0] ?
     540                 :          3 :                 journal->j_revoke_table[1] : journal->j_revoke_table[0];
     541                 :            : 
     542                 :          3 :         for (i = 0; i < revoke->hash_size; i++) {
     543                 :          3 :                 hash_list = &revoke->hash_table[i];
     544                 :            : 
     545                 :          3 :                 while (!list_empty(hash_list)) {
     546                 :          3 :                         record = (struct jbd2_revoke_record_s *)
     547                 :            :                                 hash_list->next;
     548                 :          3 :                         write_one_revoke_record(transaction, log_bufs,
     549                 :            :                                                 &descriptor, &offset, record);
     550                 :            :                         count++;
     551                 :            :                         list_del(&record->hash);
     552                 :          3 :                         kmem_cache_free(jbd2_revoke_record_cache, record);
     553                 :            :                 }
     554                 :            :         }
     555                 :          3 :         if (descriptor)
     556                 :          3 :                 flush_descriptor(journal, descriptor, offset);
     557                 :            :         jbd_debug(1, "Wrote %d revoke records\n", count);
     558                 :          3 : }
     559                 :            : 
     560                 :            : /*
     561                 :            :  * Write out one revoke record.  We need to create a new descriptor
     562                 :            :  * block if the old one is full or if we have not already created one.
     563                 :            :  */
     564                 :            : 
     565                 :          3 : static void write_one_revoke_record(transaction_t *transaction,
     566                 :            :                                     struct list_head *log_bufs,
     567                 :            :                                     struct buffer_head **descriptorp,
     568                 :            :                                     int *offsetp,
     569                 :            :                                     struct jbd2_revoke_record_s *record)
     570                 :            : {
     571                 :          3 :         journal_t *journal = transaction->t_journal;
     572                 :            :         int csum_size = 0;
     573                 :            :         struct buffer_head *descriptor;
     574                 :            :         int sz, offset;
     575                 :            : 
     576                 :            :         /* If we are already aborting, this all becomes a noop.  We
     577                 :            :            still need to go round the loop in
     578                 :            :            jbd2_journal_write_revoke_records in order to free all of the
     579                 :            :            revoke records: only the IO to the journal is omitted. */
     580                 :          3 :         if (is_journal_aborted(journal))
     581                 :            :                 return;
     582                 :            : 
     583                 :          3 :         descriptor = *descriptorp;
     584                 :          3 :         offset = *offsetp;
     585                 :            : 
     586                 :            :         /* Do we need to leave space at the end for a checksum? */
     587                 :          3 :         if (jbd2_journal_has_csum_v2or3(journal))
     588                 :            :                 csum_size = sizeof(struct jbd2_journal_block_tail);
     589                 :            : 
     590                 :          3 :         if (jbd2_has_feature_64bit(journal))
     591                 :            :                 sz = 8;
     592                 :            :         else
     593                 :            :                 sz = 4;
     594                 :            : 
     595                 :            :         /* Make sure we have a descriptor with space left for the record */
     596                 :          3 :         if (descriptor) {
     597                 :          3 :                 if (offset + sz > journal->j_blocksize - csum_size) {
     598                 :          0 :                         flush_descriptor(journal, descriptor, offset);
     599                 :            :                         descriptor = NULL;
     600                 :            :                 }
     601                 :            :         }
     602                 :            : 
     603                 :          3 :         if (!descriptor) {
     604                 :          3 :                 descriptor = jbd2_journal_get_descriptor_buffer(transaction,
     605                 :            :                                                         JBD2_REVOKE_BLOCK);
     606                 :          3 :                 if (!descriptor)
     607                 :            :                         return;
     608                 :            : 
     609                 :            :                 /* Record it so that we can wait for IO completion later */
     610                 :            :                 BUFFER_TRACE(descriptor, "file in log_bufs");
     611                 :            :                 jbd2_file_log_bh(log_bufs, descriptor);
     612                 :            : 
     613                 :            :                 offset = sizeof(jbd2_journal_revoke_header_t);
     614                 :          3 :                 *descriptorp = descriptor;
     615                 :            :         }
     616                 :            : 
     617                 :          3 :         if (jbd2_has_feature_64bit(journal))
     618                 :          0 :                 * ((__be64 *)(&descriptor->b_data[offset])) =
     619                 :          0 :                         cpu_to_be64(record->blocknr);
     620                 :            :         else
     621                 :          3 :                 * ((__be32 *)(&descriptor->b_data[offset])) =
     622                 :          3 :                         cpu_to_be32(record->blocknr);
     623                 :          3 :         offset += sz;
     624                 :            : 
     625                 :          3 :         *offsetp = offset;
     626                 :            : }
     627                 :            : 
     628                 :            : /*
     629                 :            :  * Flush a revoke descriptor out to the journal.  If we are aborting,
     630                 :            :  * this is a noop; otherwise we are generating a buffer which needs to
     631                 :            :  * be waited for during commit, so it has to go onto the appropriate
     632                 :            :  * journal buffer list.
     633                 :            :  */
     634                 :            : 
     635                 :          3 : static void flush_descriptor(journal_t *journal,
     636                 :            :                              struct buffer_head *descriptor,
     637                 :            :                              int offset)
     638                 :            : {
     639                 :            :         jbd2_journal_revoke_header_t *header;
     640                 :            : 
     641                 :          3 :         if (is_journal_aborted(journal))
     642                 :          3 :                 return;
     643                 :            : 
     644                 :          3 :         header = (jbd2_journal_revoke_header_t *)descriptor->b_data;
     645                 :          3 :         header->r_count = cpu_to_be32(offset);
     646                 :          3 :         jbd2_descriptor_block_csum_set(journal, descriptor);
     647                 :            : 
     648                 :            :         set_buffer_jwrite(descriptor);
     649                 :            :         BUFFER_TRACE(descriptor, "write");
     650                 :            :         set_buffer_dirty(descriptor);
     651                 :          3 :         write_dirty_buffer(descriptor, REQ_SYNC);
     652                 :            : }
     653                 :            : #endif
     654                 :            : 
     655                 :            : /*
     656                 :            :  * Revoke support for recovery.
     657                 :            :  *
     658                 :            :  * Recovery needs to be able to:
     659                 :            :  *
     660                 :            :  *  record all revoke records, including the tid of the latest instance
     661                 :            :  *  of each revoke in the journal
     662                 :            :  *
     663                 :            :  *  check whether a given block in a given transaction should be replayed
     664                 :            :  *  (ie. has not been revoked by a revoke record in that or a subsequent
     665                 :            :  *  transaction)
     666                 :            :  *
     667                 :            :  *  empty the revoke table after recovery.
     668                 :            :  */
     669                 :            : 
     670                 :            : /*
     671                 :            :  * First, setting revoke records.  We create a new revoke record for
     672                 :            :  * every block ever revoked in the log as we scan it for recovery, and
     673                 :            :  * we update the existing records if we find multiple revokes for a
     674                 :            :  * single block.
     675                 :            :  */
     676                 :            : 
     677                 :          1 : int jbd2_journal_set_revoke(journal_t *journal,
     678                 :            :                        unsigned long long blocknr,
     679                 :            :                        tid_t sequence)
     680                 :            : {
     681                 :            :         struct jbd2_revoke_record_s *record;
     682                 :            : 
     683                 :          1 :         record = find_revoke_record(journal, blocknr);
     684                 :          1 :         if (record) {
     685                 :            :                 /* If we have multiple occurrences, only record the
     686                 :            :                  * latest sequence number in the hashed record */
     687                 :          1 :                 if (tid_gt(sequence, record->sequence))
     688                 :          1 :                         record->sequence = sequence;
     689                 :            :                 return 0;
     690                 :            :         }
     691                 :          1 :         return insert_revoke_hash(journal, blocknr, sequence);
     692                 :            : }
     693                 :            : 
     694                 :            : /*
     695                 :            :  * Test revoke records.  For a given block referenced in the log, has
     696                 :            :  * that block been revoked?  A revoke record with a given transaction
     697                 :            :  * sequence number revokes all blocks in that transaction and earlier
     698                 :            :  * ones, but later transactions still need replayed.
     699                 :            :  */
     700                 :            : 
     701                 :          1 : int jbd2_journal_test_revoke(journal_t *journal,
     702                 :            :                         unsigned long long blocknr,
     703                 :            :                         tid_t sequence)
     704                 :            : {
     705                 :            :         struct jbd2_revoke_record_s *record;
     706                 :            : 
     707                 :          1 :         record = find_revoke_record(journal, blocknr);
     708                 :          1 :         if (!record)
     709                 :            :                 return 0;
     710                 :          1 :         if (tid_gt(sequence, record->sequence))
     711                 :            :                 return 0;
     712                 :          1 :         return 1;
     713                 :            : }
     714                 :            : 
     715                 :            : /*
     716                 :            :  * Finally, once recovery is over, we need to clear the revoke table so
     717                 :            :  * that it can be reused by the running filesystem.
     718                 :            :  */
     719                 :            : 
     720                 :          1 : void jbd2_journal_clear_revoke(journal_t *journal)
     721                 :            : {
     722                 :            :         int i;
     723                 :            :         struct list_head *hash_list;
     724                 :            :         struct jbd2_revoke_record_s *record;
     725                 :            :         struct jbd2_revoke_table_s *revoke;
     726                 :            : 
     727                 :          1 :         revoke = journal->j_revoke;
     728                 :            : 
     729                 :          1 :         for (i = 0; i < revoke->hash_size; i++) {
     730                 :          1 :                 hash_list = &revoke->hash_table[i];
     731                 :          1 :                 while (!list_empty(hash_list)) {
     732                 :          1 :                         record = (struct jbd2_revoke_record_s*) hash_list->next;
     733                 :            :                         list_del(&record->hash);
     734                 :          1 :                         kmem_cache_free(jbd2_revoke_record_cache, record);
     735                 :            :                 }
     736                 :            :         }
     737                 :          1 : }
    

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