1 files changed, 105 insertions, 29 deletions

diff --git a/fs/reiserfs/journal.c b/fs/reiserfs/journal.c
index 90622200b39c..438c71f0bc91 100644
--- a/fs/reiserfs/journal.c
+++ b/fs/reiserfs/journal.c
@@ -429,21 +429,6 @@ static void clear_prepared_bits(struct buffer_head *bh)
         clear_buffer_journal_restore_dirty(bh);
 }
 
-/* utility function to force a BUG if it is called without the big
-** kernel lock held.  caller is the string printed just before calling BUG()
-*/
-void reiserfs_check_lock_depth(struct super_block *sb, char *caller)
-{
-#ifdef CONFIG_SMP
-        if (current->lock_depth < 0) {
-                reiserfs_panic(sb, "journal-1", "%s called without kernel "
-                               "lock held", caller);
-        }
-#else
-        ;
-#endif
-}
-
 /* return a cnode with same dev, block number and size in table, or null if not found */
 static inline struct reiserfs_journal_cnode *get_journal_hash_dev(struct
                                                                   super_block
@@ -552,11 +537,48 @@ static inline void insert_journal_hash(struct reiserfs_journal_cnode **table,
         journal_hash(table, cn->sb, cn->blocknr) = cn;
 }
 
+/*
+ * Several mutexes depend on the write lock.
+ * However sometimes we want to relax the write lock while we hold
+ * these mutexes, according to the release/reacquire on schedule()
+ * properties of the Bkl that were used.
+ * Reiserfs performances and locking were based on this scheme.
+ * Now that the write lock is a mutex and not the bkl anymore, doing so
+ * may result in a deadlock:
+ *
+ * A acquire write_lock
+ * A acquire j_commit_mutex
+ * A release write_lock and wait for something
+ * B acquire write_lock
+ * B can't acquire j_commit_mutex and sleep
+ * A can't acquire write lock anymore
+ * deadlock
+ *
+ * What we do here is avoiding such deadlock by playing the same game
+ * than the Bkl: if we can't acquire a mutex that depends on the write lock,
+ * we release the write lock, wait a bit and then retry.
+ *
+ * The mutexes concerned by this hack are:
+ * - The commit mutex of a journal list
+ * - The flush mutex
+ * - The journal lock
+ */
+static inline void reiserfs_mutex_lock_safe(struct mutex *m,
+                               struct super_block *s)
+{
+        while (!mutex_trylock(m)) {
+                reiserfs_write_unlock(s);
+                schedule();
+                reiserfs_write_lock(s);
+        }
+}
+
 /* lock the current transaction */
 static inline void lock_journal(struct super_block *sb)
 {
         PROC_INFO_INC(sb, journal.lock_journal);
-        mutex_lock(&SB_JOURNAL(sb)->j_mutex);
+
+        reiserfs_mutex_lock_safe(&SB_JOURNAL(sb)->j_mutex, sb);
 }
 
 /* unlock the current transaction */
@@ -708,7 +730,9 @@ static void check_barrier_completion(struct super_block *s,
                 disable_barrier(s);
                 set_buffer_uptodate(bh);
                 set_buffer_dirty(bh);
+                reiserfs_write_unlock(s);
                 sync_dirty_buffer(bh);
+                reiserfs_write_lock(s);
         }
 }
 
@@ -996,8 +1020,13 @@ static int reiserfs_async_progress_wait(struct super_block *s)
 {
         DEFINE_WAIT(wait);
         struct reiserfs_journal *j = SB_JOURNAL(s);
-        if (atomic_read(&j->j_async_throttle))
+
+        if (atomic_read(&j->j_async_throttle)) {
+                reiserfs_write_unlock(s);
                 congestion_wait(BLK_RW_ASYNC, HZ / 10);
+                reiserfs_write_lock(s);
+        }
+
         return 0;
 }
 
@@ -1043,7 +1072,8 @@ static int flush_commit_list(struct super_block *s,
         }
 
         /* make sure nobody is trying to flush this one at the same time */
-        mutex_lock(&jl->j_commit_mutex);
+        reiserfs_mutex_lock_safe(&jl->j_commit_mutex, s);
+
         if (!journal_list_still_alive(s, trans_id)) {
                 mutex_unlock(&jl->j_commit_mutex);
                 goto put_jl;
@@ -1061,12 +1091,17 @@ static int flush_commit_list(struct super_block *s,
 
         if (!list_empty(&jl->j_bh_list)) {
                 int ret;
-                unlock_kernel();
+
+                /*
+                 * We might sleep in numerous places inside
+                 * write_ordered_buffers. Relax the write lock.
+                 */
+                reiserfs_write_unlock(s);
                 ret = write_ordered_buffers(&journal->j_dirty_buffers_lock,
                                             journal, jl, &jl->j_bh_list);
                 if (ret < 0 && retval == 0)
                         retval = ret;
-                lock_kernel();
+                reiserfs_write_lock(s);
         }
         BUG_ON(!list_empty(&jl->j_bh_list));
         /*
@@ -1114,12 +1149,19 @@ static int flush_commit_list(struct super_block *s,
                 bn = SB_ONDISK_JOURNAL_1st_BLOCK(s) +
                     (jl->j_start + i) % SB_ONDISK_JOURNAL_SIZE(s);
                 tbh = journal_find_get_block(s, bn);
+
+                reiserfs_write_unlock(s);
                 wait_on_buffer(tbh);
+                reiserfs_write_lock(s);
                 // since we're using ll_rw_blk above, it might have skipped over
                 // a locked buffer.  Double check here
                 //
-                if (buffer_dirty(tbh))  /* redundant, sync_dirty_buffer() checks */
+                /* redundant, sync_dirty_buffer() checks */
+                if (buffer_dirty(tbh)) {
+                        reiserfs_write_unlock(s);
                         sync_dirty_buffer(tbh);
+                        reiserfs_write_lock(s);
+                }
                 if (unlikely(!buffer_uptodate(tbh))) {
 #ifdef CONFIG_REISERFS_CHECK
                         reiserfs_warning(s, "journal-601",
@@ -1143,10 +1185,15 @@ static int flush_commit_list(struct super_block *s,
                         if (buffer_dirty(jl->j_commit_bh))
                                 BUG();
                         mark_buffer_dirty(jl->j_commit_bh) ;
+                        reiserfs_write_unlock(s);
                         sync_dirty_buffer(jl->j_commit_bh) ;
+                        reiserfs_write_lock(s);
                 }
-        } else
+        } else {
+                reiserfs_write_unlock(s);
                 wait_on_buffer(jl->j_commit_bh);
+                reiserfs_write_lock(s);
+        }
 
         check_barrier_completion(s, jl->j_commit_bh);
 
@@ -1286,7 +1333,9 @@ static int _update_journal_header_block(struct super_block *sb,
 
         if (trans_id >= journal->j_last_flush_trans_id) {
                 if (buffer_locked((journal->j_header_bh))) {
+                        reiserfs_write_unlock(sb);
                         wait_on_buffer((journal->j_header_bh));
+                        reiserfs_write_lock(sb);
                         if (unlikely(!buffer_uptodate(journal->j_header_bh))) {
 #ifdef CONFIG_REISERFS_CHECK
                                 reiserfs_warning(sb, "journal-699",
@@ -1312,12 +1361,16 @@ static int _update_journal_header_block(struct super_block *sb,
                                 disable_barrier(sb);
                                 goto sync;
                         }
+                        reiserfs_write_unlock(sb);
                         wait_on_buffer(journal->j_header_bh);
+                        reiserfs_write_lock(sb);
                         check_barrier_completion(sb, journal->j_header_bh);
                 } else {
                       sync:
                         set_buffer_dirty(journal->j_header_bh);
+                        reiserfs_write_unlock(sb);
                         sync_dirty_buffer(journal->j_header_bh);
+                        reiserfs_write_lock(sb);
                 }
                 if (!buffer_uptodate(journal->j_header_bh)) {
                         reiserfs_warning(sb, "journal-837",
@@ -1409,7 +1462,7 @@ static int flush_journal_list(struct super_block *s,
 
         /* if flushall == 0, the lock is already held */
         if (flushall) {
-                mutex_lock(&journal->j_flush_mutex);
+                reiserfs_mutex_lock_safe(&journal->j_flush_mutex, s);
         } else if (mutex_trylock(&journal->j_flush_mutex)) {
                 BUG();
         }
@@ -1553,7 +1606,11 @@ static int flush_journal_list(struct super_block *s,
                                         reiserfs_panic(s, "journal-1011",
                                                        "cn->bh is NULL");
                                 }
+
+                                reiserfs_write_unlock(s);
                                 wait_on_buffer(cn->bh);
+                                reiserfs_write_lock(s);
+
                                 if (!cn->bh) {
                                         reiserfs_panic(s, "journal-1012",
                                                        "cn->bh is NULL");
@@ -1973,11 +2030,19 @@ static int do_journal_release(struct reiserfs_transaction_handle *th,
         reiserfs_mounted_fs_count--;
         /* wait for all commits to finish */
         cancel_delayed_work(&SB_JOURNAL(sb)->j_work);
+
+        /*
+         * We must release the write lock here because
+         * the workqueue job (flush_async_commit) needs this lock
+         */
+        reiserfs_write_unlock(sb);
         flush_workqueue(commit_wq);
+
         if (!reiserfs_mounted_fs_count) {
                 destroy_workqueue(commit_wq);
                 commit_wq = NULL;
         }
+        reiserfs_write_lock(sb);
 
         free_journal_ram(sb);
 
@@ -2243,7 +2308,11 @@ static int journal_read_transaction(struct super_block *sb,
         /* read in the log blocks, memcpy to the corresponding real block */
         ll_rw_block(READ, get_desc_trans_len(desc), log_blocks);
         for (i = 0; i < get_desc_trans_len(desc); i++) {
+
+                reiserfs_write_unlock(sb);
                 wait_on_buffer(log_blocks[i]);
+                reiserfs_write_lock(sb);
+
                 if (!buffer_uptodate(log_blocks[i])) {
                         reiserfs_warning(sb, "journal-1212",
                                          "REPLAY FAILURE fsck required! "
@@ -2964,8 +3033,11 @@ static void queue_log_writer(struct super_block *s)
         init_waitqueue_entry(&wait, current);
         add_wait_queue(&journal->j_join_wait, &wait);
         set_current_state(TASK_UNINTERRUPTIBLE);
-        if (test_bit(J_WRITERS_QUEUED, &journal->j_state))
+        if (test_bit(J_WRITERS_QUEUED, &journal->j_state)) {
+                reiserfs_write_unlock(s);
                 schedule();
+                reiserfs_write_lock(s);
+        }
         __set_current_state(TASK_RUNNING);
         remove_wait_queue(&journal->j_join_wait, &wait);
 }
@@ -2982,7 +3054,9 @@ static void let_transaction_grow(struct super_block *sb, unsigned int trans_id)
         struct reiserfs_journal *journal = SB_JOURNAL(sb);
         unsigned long bcount = journal->j_bcount;
         while (1) {
+                reiserfs_write_unlock(sb);
                 schedule_timeout_uninterruptible(1);
+                reiserfs_write_lock(sb);
                 journal->j_current_jl->j_state |= LIST_COMMIT_PENDING;
                 while ((atomic_read(&journal->j_wcount) > 0 ||
                         atomic_read(&journal->j_jlock)) &&
@@ -3033,7 +3107,9 @@ static int do_journal_begin_r(struct reiserfs_transaction_handle *th,
 
         if (test_bit(J_WRITERS_BLOCKED, &journal->j_state)) {
                 unlock_journal(sb);
+                reiserfs_write_unlock(sb);
                 reiserfs_wait_on_write_block(sb);
+                reiserfs_write_lock(sb);
                 PROC_INFO_INC(sb, journal.journal_relock_writers);
                 goto relock;
         }
@@ -3506,14 +3582,14 @@ static void flush_async_commits(struct work_struct *work)
         struct reiserfs_journal_list *jl;
         struct list_head *entry;
 
-        lock_kernel();
+        reiserfs_write_lock(sb);
         if (!list_empty(&journal->j_journal_list)) {
                 /* last entry is the youngest, commit it and you get everything */
                 entry = journal->j_journal_list.prev;
                 jl = JOURNAL_LIST_ENTRY(entry);
                 flush_commit_list(sb, jl, 1);
         }
-        unlock_kernel();
+        reiserfs_write_unlock(sb);
 }
 
 /*
@@ -4041,7 +4117,7 @@ static int do_journal_end(struct reiserfs_transaction_handle *th,
          * the new transaction is fully setup, and we've already flushed the
          * ordered bh list
          */
-        mutex_lock(&jl->j_commit_mutex);
+        reiserfs_mutex_lock_safe(&jl->j_commit_mutex, sb);
 
         /* save the transaction id in case we need to commit it later */
         commit_trans_id = jl->j_trans_id;
@@ -4203,10 +4279,10 @@ static int do_journal_end(struct reiserfs_transaction_handle *th,
          * is lost.
          */
         if (!list_empty(&jl->j_tail_bh_list)) {
-                unlock_kernel();
+                reiserfs_write_unlock(sb);
                 write_ordered_buffers(&journal->j_dirty_buffers_lock,
                                       journal, jl, &jl->j_tail_bh_list);
-                lock_kernel();
+                reiserfs_write_lock(sb);
         }
         BUG_ON(!list_empty(&jl->j_tail_bh_list));
         mutex_unlock(&jl->j_commit_mutex);