* We're outside-transaction here. Either or both of j_running_transaction
* and j_committing_transaction may be NULL.
*/
-static int journal_unmap_buffer(journal_t *journal, struct buffer_head *bh)
+static int journal_unmap_buffer(journal_t *journal, struct buffer_head *bh,
+ int partial_page)
{
transaction_t *transaction;
struct journal_head *jh;
int may_free = 1;
- int ret;
BUFFER_TRACE(bh, "entry");
+retry:
/*
* It is safe to proceed here without the j_list_lock because the
* buffers cannot be stolen by try_to_free_buffers as long as we are
* clear the buffer dirty bit at latest at the moment when the
* transaction marking the buffer as freed in the filesystem
* structures is committed because from that moment on the
- * buffer can be reallocated and used by a different page.
+ * block can be reallocated and used by a different page.
* Since the block hasn't been freed yet but the inode has
* already been added to orphan list, it is safe for us to add
* the buffer to BJ_Forget list of the newest transaction.
+ *
+ * Also we have to clear buffer_mapped flag of a truncated buffer
+ * because the buffer_head may be attached to the page straddling
+ * i_size (can happen only when blocksize < pagesize) and thus the
+ * buffer_head can be reused when the file is extended again. So we end
+ * up keeping around invalidated buffers attached to transactions'
+ * BJ_Forget list just to stop checkpointing code from cleaning up
+ * the transaction this buffer was modified in.
*/
transaction = jh->b_transaction;
if (transaction == NULL) {
* committed, the buffer won't be needed any
* longer. */
JBUFFER_TRACE(jh, "checkpointed: add to BJ_Forget");
- ret = __dispose_buffer(jh,
+ may_free = __dispose_buffer(jh,
journal->j_running_transaction);
- journal_put_journal_head(jh);
- spin_unlock(&journal->j_list_lock);
- jbd_unlock_bh_state(bh);
- spin_unlock(&journal->j_state_lock);
- return ret;
+ goto zap_buffer;
} else {
/* There is no currently-running transaction. So the
* orphan record which we wrote for this file must have
* the committing transaction, if it exists. */
if (journal->j_committing_transaction) {
JBUFFER_TRACE(jh, "give to committing trans");
- ret = __dispose_buffer(jh,
+ may_free = __dispose_buffer(jh,
journal->j_committing_transaction);
- journal_put_journal_head(jh);
- spin_unlock(&journal->j_list_lock);
- jbd_unlock_bh_state(bh);
- spin_unlock(&journal->j_state_lock);
- return ret;
+ goto zap_buffer;
} else {
/* The orphan record's transaction has
* committed. We can cleanse this buffer */
}
/*
* The buffer is committing, we simply cannot touch
- * it. So we just set j_next_transaction to the
- * running transaction (if there is one) and mark
- * buffer as freed so that commit code knows it should
- * clear dirty bits when it is done with the buffer.
+ * it. If the page is straddling i_size we have to wait
+ * for commit and try again.
+ */
+ if (partial_page) {
+ tid_t tid = journal->j_committing_transaction->t_tid;
+
+ journal_put_journal_head(jh);
+ spin_unlock(&journal->j_list_lock);
+ jbd_unlock_bh_state(bh);
+ spin_unlock(&journal->j_state_lock);
+ unlock_buffer(bh);
+ log_wait_commit(journal, tid);
+ lock_buffer(bh);
+ goto retry;
+ }
+ /*
+ * OK, buffer won't be reachable after truncate. We just set
+ * j_next_transaction to the running transaction (if there is
+ * one) and mark buffer as freed so that commit code knows it
+ * should clear dirty bits when it is done with the buffer.
*/
set_buffer_freed(bh);
if (journal->j_running_transaction && buffer_jbddirty(bh))
}
zap_buffer:
+ /*
+ * This is tricky. Although the buffer is truncated, it may be reused
+ * if blocksize < pagesize and it is attached to the page straddling
+ * EOF. Since the buffer might have been added to BJ_Forget list of the
+ * running transaction, journal_get_write_access() won't clear
+ * b_modified and credit accounting gets confused. So clear b_modified
+ * here. */
+ jh->b_modified = 0;
journal_put_journal_head(jh);
zap_buffer_no_jh:
spin_unlock(&journal->j_list_lock);
if (offset <= curr_off) {
/* This block is wholly outside the truncation point */
lock_buffer(bh);
- may_free &= journal_unmap_buffer(journal, bh);
+ may_free &= journal_unmap_buffer(journal, bh,
+ offset > 0);
unlock_buffer(bh);
}
curr_off = next_off;
git.openpandora.org / pandora-kernel.git / blobdiff