From: Theodore Ts'o <tytso@mit.edu>
Date: Mon, 15 Jul 2013 04:09:56 +0000 (-0400)
Subject: ext4: block direct I/O writes during ext4_truncate
X-Git-Tag: next-20130717~62^2~2
X-Git-Url: https://git.karo-electronics.de/?a=commitdiff_plain;h=839ffb2667d0ccb593efd74b42219fcc1d2b18f6;p=karo-tx-linux.git

ext4: block direct I/O writes during ext4_truncate

Just as in ext4_punch_hole() it is important that we block DIO writes
while the truncate is proceeding, since during the overwriting DIO
write, we drop i_mutex, which means a truncate could start while the
Direct I/O operation is still in progress.

Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>
Cc: stable@vger.kernel.org
---

diff --git a/fs/ext4/inode.c b/fs/ext4/inode.c
index 98b9bff92a8a..3c5edf29e2ae 100644
--- a/fs/ext4/inode.c
+++ b/fs/ext4/inode.c
@@ -3659,12 +3659,16 @@ void ext4_truncate(struct inode *inode)
 	if (inode->i_size == 0 && !test_opt(inode->i_sb, NO_AUTO_DA_ALLOC))
 		ext4_set_inode_state(inode, EXT4_STATE_DA_ALLOC_CLOSE);
 
+	/* Wait all existing dio workers, newcomers will block on i_mutex */
+	ext4_inode_block_unlocked_dio(inode);
+	inode_dio_wait(inode);
+
 	if (ext4_has_inline_data(inode)) {
 		int has_inline = 1;
 
 		ext4_inline_data_truncate(inode, &has_inline);
 		if (has_inline)
-			return;
+			goto out_resume;
 	}
 
 	if (ext4_test_inode_flag(inode, EXT4_INODE_EXTENTS))
@@ -3675,7 +3679,7 @@ void ext4_truncate(struct inode *inode)
 	handle = ext4_journal_start(inode, EXT4_HT_TRUNCATE, credits);
 	if (IS_ERR(handle)) {
 		ext4_std_error(inode->i_sb, PTR_ERR(handle));
-		return;
+		goto out_resume;
 	}
 
 	if (inode->i_size & (inode->i_sb->s_blocksize - 1))
@@ -3722,6 +3726,8 @@ out_stop:
 	ext4_mark_inode_dirty(handle, inode);
 	ext4_journal_stop(handle);
 
+out_resume:
+	ext4_inode_resume_unlocked_dio(inode);
 	trace_ext4_truncate_exit(inode);
 }