2 files changed, 74 insertions, 31 deletions

diff --git a/fs/jbd2/commit.c b/fs/jbd2/commit.c
index af5280fb579b..3091d42992f0 100644
--- a/fs/jbd2/commit.c
+++ b/fs/jbd2/commit.c
@@ -1014,17 +1014,35 @@ restart_loop:
                  * there's no point in keeping a checkpoint record for
                  * it. */
 
-                /* A buffer which has been freed while still being
-                 * journaled by a previous transaction may end up still
-                 * being dirty here, but we want to avoid writing back
-                 * that buffer in the future after the "add to orphan"
-                 * operation been committed,  That's not only a performance
-                 * gain, it also stops aliasing problems if the buffer is
-                 * left behind for writeback and gets reallocated for another
-                 * use in a different page. */
-                if (buffer_freed(bh) && !jh->b_next_transaction) {
-                        clear_buffer_freed(bh);
-                        clear_buffer_jbddirty(bh);
+                /*
+                * A buffer which has been freed while still being journaled by
+                * a previous transaction.
+                */
+                if (buffer_freed(bh)) {
+                        /*
+                         * If the running transaction is the one containing
+                         * "add to orphan" operation (b_next_transaction !=
+                         * NULL), we have to wait for that transaction to
+                         * commit before we can really get rid of the buffer.
+                         * So just clear b_modified to not confuse transaction
+                         * credit accounting and refile the buffer to
+                         * BJ_Forget of the running transaction. If the just
+                         * committed transaction contains "add to orphan"
+                         * operation, we can completely invalidate the buffer
+                         * now. We are rather through in that since the
+                         * buffer may be still accessible when blocksize <
+                         * pagesize and it is attached to the last partial
+                         * page.
+                         */
+                        jh->b_modified = 0;
+                        if (!jh->b_next_transaction) {
+                                clear_buffer_freed(bh);
+                                clear_buffer_jbddirty(bh);
+                                clear_buffer_mapped(bh);
+                                clear_buffer_new(bh);
+                                clear_buffer_req(bh);
+                                bh->b_bdev = NULL;
+                        }
                 }
 
                 if (buffer_jbddirty(bh)) {
diff --git a/fs/jbd2/transaction.c b/fs/jbd2/transaction.c
index fb1ab9533b67..a74ba4659549 100644
--- a/fs/jbd2/transaction.c
+++ b/fs/jbd2/transaction.c
@@ -1841,15 +1841,16 @@ static int __dispose_buffer(struct journal_head *jh, transaction_t *transaction)
  * 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
@@ -1878,10 +1879,18 @@ static int journal_unmap_buffer(journal_t *journal, struct buffer_head *bh)
          * 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) {
@@ -1908,13 +1917,9 @@ static int journal_unmap_buffer(journal_t *journal, struct buffer_head *bh)
                          * 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);
-                        jbd2_journal_put_journal_head(jh);
-                        spin_unlock(&journal->j_list_lock);
-                        jbd_unlock_bh_state(bh);
-                        write_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
@@ -1922,13 +1927,9 @@ static int journal_unmap_buffer(journal_t *journal, struct buffer_head *bh)
                          * 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);
-                                jbd2_journal_put_journal_head(jh);
-                                spin_unlock(&journal->j_list_lock);
-                                jbd_unlock_bh_state(bh);
-                                write_unlock(&journal->j_state_lock);
-                                return ret;
+                                goto zap_buffer;
                         } else {
                                 /* The orphan record's transaction has
                                  * committed.  We can cleanse this buffer */
@@ -1940,10 +1941,24 @@ static int journal_unmap_buffer(journal_t *journal, struct buffer_head *bh)
                 JBUFFER_TRACE(jh, "on committing transaction");
                 /*
                  * 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;
+
+                        jbd2_journal_put_journal_head(jh);
+                        spin_unlock(&journal->j_list_lock);
+                        jbd_unlock_bh_state(bh);
+                        write_unlock(&journal->j_state_lock);
+                        jbd2_log_wait_commit(journal, tid);
+                        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))
@@ -1966,6 +1981,15 @@ static int journal_unmap_buffer(journal_t *journal, struct buffer_head *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;
         jbd2_journal_put_journal_head(jh);
 zap_buffer_no_jh:
         spin_unlock(&journal->j_list_lock);
@@ -2017,7 +2041,8 @@ void jbd2_journal_invalidatepage(journal_t *journal,
                 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;