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-rw-r--r--fs/jbd/revoke.c44
1 files changed, 30 insertions, 14 deletions
diff --git a/fs/jbd/revoke.c b/fs/jbd/revoke.c
index c7bd649bbbdc..da6cd9bdaabc 100644
--- a/fs/jbd/revoke.c
+++ b/fs/jbd/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* buffer has been revoked.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 jbd_revoke_table_s
#ifdef __KERNEL__
static void write_one_revoke_record(journal_t *, transaction_t *,
struct journal_head **, int *,
- struct jbd_revoke_record_s *);
-static void flush_descriptor(journal_t *, struct journal_head *, int);
+ struct jbd_revoke_record_s *, int);
+static void flush_descriptor(journal_t *, struct journal_head *, int, int);
#endif
/* Utility functions to maintain the revoke table */
@@ -402,8 +422,6 @@ int journal_revoke(handle_t *handle, unsigned 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 journal_cancel_revoke(handle_t *handle, struct journal_head *jh)
{
@@ -481,12 +499,9 @@ void 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 journal_write_revoke_records(journal_t *journal,
- transaction_t *transaction)
+ transaction_t *transaction, int write_op)
{
struct journal_head *descriptor;
struct jbd_revoke_record_s *record;
@@ -510,14 +525,14 @@ void 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(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);
}
@@ -530,7 +545,8 @@ static void write_one_revoke_record(journal_t *journal,
transaction_t *transaction,
struct journal_head **descriptorp,
int *offsetp,
- struct jbd_revoke_record_s *record)
+ struct jbd_revoke_record_s *record,
+ int write_op)
{
struct journal_head *descriptor;
int offset;
@@ -549,7 +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;
}
}
@@ -586,7 +602,7 @@ 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)
{
journal_revoke_header_t *header;
struct buffer_head *bh = jh2bh(descriptor);
@@ -601,7 +617,7 @@ 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