ext4: Add mount option to set kjournald's I/O priority

Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>
Cc: Jens Axboe <jens.axboe@oracle.com>

1 files changed, 7 insertions, 0 deletions

diff --git a/Documentation/filesystems/ext4.txt b/Documentation/filesystems/ext4.txt
index 9ec29d86ff8b..8938949b201e 100644
--- a/Documentation/filesystems/ext4.txt
+++ b/Documentation/filesystems/ext4.txt
@@ -308,6 +308,13 @@ min_batch_time=usec	This parameter sets the commit time (as
                         multi-threaded, synchronous workloads on very
                         fast disks, at the cost of increasing latency.
 
+journal_ioprio=prio     The I/O priority (from 0 to 7, where 0 is the
+                        highest priorty) which should be used for I/O
+                        operations submitted by kjournald2 during a
+                        commit operation.  This defaults to 3, which is
+                        a slightly higher priority than the default I/O
+                        priority.
+
 Data Mode
 =========
 There are 3 different data modes: