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-rw-r--r--Documentation/filesystems/ext4.txt18
1 files changed, 15 insertions, 3 deletions
diff --git a/Documentation/filesystems/ext4.txt b/Documentation/filesystems/ext4.txt
index bf4f4b7..af6885c 100644
--- a/Documentation/filesystems/ext4.txt
+++ b/Documentation/filesystems/ext4.txt
@@ -134,9 +134,15 @@ ro Mount filesystem read only. Note that ext4 will
mount options "ro,noload" can be used to prevent
writes to the filesystem.
+journal_checksum Enable checksumming of the journal transactions.
+ This will allow the recovery code in e2fsck and the
+ kernel to detect corruption in the kernel. It is a
+ compatible change and will be ignored by older kernels.
+
journal_async_commit Commit block can be written to disk without waiting
for descriptor blocks. If enabled older kernels cannot
- mount the device.
+ mount the device. This will enable 'journal_checksum'
+ internally.
journal=update Update the ext4 file system's journal to the current
format.
@@ -147,8 +153,8 @@ journal_dev=devnum When the external journal device's major/minor numbers
identified through its new major/minor numbers encoded
in devnum.
-noload Don't load the journal on mounting. Note that
- if the filesystem was not unmounted cleanly,
+norecovery Don't load the journal on mounting. Note that
+noload if the filesystem was not unmounted cleanly,
skipping the journal replay will lead to the
filesystem containing inconsistencies that can
lead to any number of problems.
@@ -347,6 +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:
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