Merge branch 'for-linus' of git://git.kernel.org/pub/scm/fs/xfs/xfs

[safe/jmp/linux-2.6] / fs / jbd2 / revoke.c

diff --git a/fs/jbd2/revoke.c b/fs/jbd2/revoke.c
index 144a206..a360b06 100644 (file)
--- a/fs/jbd2/revoke.c
+++ b/fs/jbd2/revoke.c
@@ -55,6 +55,25 @@
  *                     need do nothing.
  * RevokeValid set, Revoked set:
  *                     buffer has been revoked.
+ *
+ * Locking rules:
+ * We keep two hash tables of revoke records. One hashtable belongs to the
+ * running transaction (is pointed to by journal->j_revoke), the other one
+ * belongs to the committing transaction. Accesses to the second hash table
+ * happen only from the kjournald and no other thread touches this table.  Also
+ * journal_switch_revoke_table() which switches which hashtable belongs to the
+ * running and which to the committing transaction is called only from
+ * kjournald. Therefore we need no locks when accessing the hashtable belonging
+ * to the committing transaction.
+ *
+ * All users operating on the hash table belonging to the running transaction
+ * have a handle to the transaction. Therefore they are safe from kjournald
+ * switching hash tables under them. For operations on the lists of entries in
+ * the hash table j_revoke_lock is used.
+ *
+ * Finally, also replay code uses the hash tables but at this moment noone else
+ * can touch them (filesystem isn't mounted yet) and hence no locking is
+ * needed.
  */
 
 #ifndef __KERNEL__
@@ -67,6 +86,7 @@
 #include <linux/slab.h>
 #include <linux/list.h>
 #include <linux/init.h>
+#include <linux/bio.h>
 #endif
 #include <linux/log2.h>
 
@@ -99,8 +119,8 @@ struct jbd2_revoke_table_s
 #ifdef __KERNEL__
 static void write_one_revoke_record(journal_t *, transaction_t *,
                                    struct journal_head **, int *,
-                                   struct jbd2_revoke_record_s *);
-static void flush_descriptor(journal_t *, struct journal_head *, int);
+                                   struct jbd2_revoke_record_s *, int);
+static void flush_descriptor(journal_t *, struct journal_head *, int, int);
 #endif
 
 /* Utility functions to maintain the revoke table */
@@ -139,7 +159,7 @@ repeat:
 oom:
        if (!journal_oom_retry)
                return -ENOMEM;
-       jbd_debug(1, "ENOMEM in %s, retrying\n", __FUNCTION__);
+       jbd_debug(1, "ENOMEM in %s, retrying\n", __func__);
        yield();
        goto repeat;
 }
@@ -401,8 +421,6 @@ int jbd2_journal_revoke(handle_t *handle, unsigned long long blocknr,
  * the second time we would still have a pending revoke to cancel.  So,
  * do not trust the Revoked bit on buffers unless RevokeValid is also
  * set.
- *
- * The caller must have the journal locked.
  */
 int jbd2_journal_cancel_revoke(handle_t *handle, struct journal_head *jh)
 {
@@ -480,12 +498,10 @@ void jbd2_journal_switch_revoke_table(journal_t *journal)
 /*
  * Write revoke records to the journal for all entries in the current
  * revoke hash, deleting the entries as we go.
- *
- * Called with the journal lock held.
  */
-
 void jbd2_journal_write_revoke_records(journal_t *journal,
-                                 transaction_t *transaction)
+                                      transaction_t *transaction,
+                                      int write_op)
 {
        struct journal_head *descriptor;
        struct jbd2_revoke_record_s *record;
@@ -509,14 +525,14 @@ void jbd2_journal_write_revoke_records(journal_t *journal,
                                hash_list->next;
                        write_one_revoke_record(journal, transaction,
                                                &descriptor, &offset,
-                                               record);
+                                               record, write_op);
                        count++;
                        list_del(&record->hash);
                        kmem_cache_free(jbd2_revoke_record_cache, record);
                }
        }
        if (descriptor)
-               flush_descriptor(journal, descriptor, offset);
+               flush_descriptor(journal, descriptor, offset, write_op);
        jbd_debug(1, "Wrote %d revoke records\n", count);
 }
 
@@ -529,7 +545,8 @@ static void write_one_revoke_record(journal_t *journal,
                                    transaction_t *transaction,
                                    struct journal_head **descriptorp,
                                    int *offsetp,
-                                   struct jbd2_revoke_record_s *record)
+                                   struct jbd2_revoke_record_s *record,
+                                   int write_op)
 {
        struct journal_head *descriptor;
        int offset;
@@ -548,7 +565,7 @@ static void write_one_revoke_record(journal_t *journal,
        /* Make sure we have a descriptor with space left for the record */
        if (descriptor) {
                if (offset == journal->j_blocksize) {
-                       flush_descriptor(journal, descriptor, offset);
+                       flush_descriptor(journal, descriptor, offset, write_op);
                        descriptor = NULL;
                }
        }
@@ -593,7 +610,7 @@ static void write_one_revoke_record(journal_t *journal,
 
 static void flush_descriptor(journal_t *journal,
                             struct journal_head *descriptor,
-                            int offset)
+                            int offset, int write_op)
 {
        jbd2_journal_revoke_header_t *header;
        struct buffer_head *bh = jh2bh(descriptor);
@@ -608,7 +625,7 @@ static void flush_descriptor(journal_t *journal,
        set_buffer_jwrite(bh);
        BUFFER_TRACE(bh, "write");
        set_buffer_dirty(bh);
-       ll_rw_block(SWRITE, 1, &bh);
+       ll_rw_block((write_op == WRITE) ? SWRITE : SWRITE_SYNC_PLUG, 1, &bh);
 }
 #endif