ext4: make trim/discard optional (and off by default)

[mirror_ubuntu-bionic-kernel.git] / Documentation / filesystems / ext4.txt

diff --git a/Documentation/filesystems/ext4.txt b/Documentation/filesystems/ext4.txt
index 6d94e0696f8c313ee5a439f5ed2f140b356500f6..26904ff6d61b60951e8d00f6a009b331d866f730 100644 (file)
--- a/Documentation/filesystems/ext4.txt
+++ b/Documentation/filesystems/ext4.txt
@@ -353,6 +353,12 @@ noauto_da_alloc            replacing existing files via patterns such as
                        system crashes before the delayed allocation
                        blocks are forced to disk.
 
+discard                Controls whether ext4 should issue discard/TRIM
+nodiscard(*)           commands to the underlying block device when
+                       blocks are freed.  This is useful for SSD devices
+                       and sparse/thinly-provisioned LUNs, but it is off
+                       by default until sufficient testing has been done.
+
 Data Mode
 =========
 There are 3 different data modes: