From 3434803242db816e51da749acfed55fd5cdada6c Mon Sep 17 00:00:00 2001
From: Jan Kara <jack@suse.cz>
Date: Tue, 26 Jul 2011 09:07:11 -0400
Subject: [PATCH] --- yaml --- r: 262117 b: refs/heads/master c:
 2d859db3e4a82a365572592d57624a5f996ed0ec h: refs/heads/master i:   262115:
 abc7baa980d01b0fc34eb8318911a93ae338b8f7 v: v3

---
 [refs]                |  2 +-
 trunk/fs/ext4/inode.c | 29 +++++++++++++++++++++++++++++
 2 files changed, 30 insertions(+), 1 deletion(-)

diff --git a/[refs] b/[refs]
index 25801b9585a3..c2f2804b0450 100644
--- a/[refs]
+++ b/[refs]
@@ -1,2 +1,2 @@
 ---
-refs/heads/master: b7ca1e8ec53259359db5313f923a0a20fa04bdb6
+refs/heads/master: 2d859db3e4a82a365572592d57624a5f996ed0ec
diff --git a/trunk/fs/ext4/inode.c b/trunk/fs/ext4/inode.c
index de50b16a8f67..43e4abd67be7 100644
--- a/trunk/fs/ext4/inode.c
+++ b/trunk/fs/ext4/inode.c
@@ -121,6 +121,33 @@ void ext4_evict_inode(struct inode *inode)
 
 	trace_ext4_evict_inode(inode);
 	if (inode->i_nlink) {
+		/*
+		 * When journalling data dirty buffers are tracked only in the
+		 * journal. So although mm thinks everything is clean and
+		 * ready for reaping the inode might still have some pages to
+		 * write in the running transaction or waiting to be
+		 * checkpointed. Thus calling jbd2_journal_invalidatepage()
+		 * (via truncate_inode_pages()) to discard these buffers can
+		 * cause data loss. Also even if we did not discard these
+		 * buffers, we would have no way to find them after the inode
+		 * is reaped and thus user could see stale data if he tries to
+		 * read them before the transaction is checkpointed. So be
+		 * careful and force everything to disk here... We use
+		 * ei->i_datasync_tid to store the newest transaction
+		 * containing inode's data.
+		 *
+		 * Note that directories do not have this problem because they
+		 * don't use page cache.
+		 */
+		if (ext4_should_journal_data(inode) &&
+		    (S_ISLNK(inode->i_mode) || S_ISREG(inode->i_mode))) {
+			journal_t *journal = EXT4_SB(inode->i_sb)->s_journal;
+			tid_t commit_tid = EXT4_I(inode)->i_datasync_tid;
+
+			jbd2_log_start_commit(journal, commit_tid);
+			jbd2_log_wait_commit(journal, commit_tid);
+			filemap_write_and_wait(&inode->i_data);
+		}
 		truncate_inode_pages(&inode->i_data, 0);
 		goto no_delete;
 	}
@@ -970,6 +997,7 @@ static int ext4_journalled_write_end(struct file *file,
 	if (new_i_size > inode->i_size)
 		i_size_write(inode, pos+copied);
 	ext4_set_inode_state(inode, EXT4_STATE_JDATA);
+	EXT4_I(inode)->i_datasync_tid = handle->h_transaction->t_tid;
 	if (new_i_size > EXT4_I(inode)->i_disksize) {
 		ext4_update_i_disksize(inode, new_i_size);
 		ret2 = ext4_mark_inode_dirty(handle, inode);
@@ -1678,6 +1706,7 @@ static int __ext4_journalled_writepage(struct page *page,
 				write_end_fn);
 	if (ret == 0)
 		ret = err;
+	EXT4_I(inode)->i_datasync_tid = handle->h_transaction->t_tid;
 	err = ext4_journal_stop(handle);
 	if (!ret)
 		ret = err;