1 files changed, 17 insertions, 4 deletions

diff --git a/Documentation/filesystems/ext4.txt b/Documentation/filesystems/ext4.txt
index 18b5ec8cea45..6d94e0696f8c 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.
@@ -282,9 +288,16 @@ stripe=n		Number of filesystem blocks that mballoc will try
                         to use for allocation size and alignment. For RAID5/6
                         systems this should be the number of data
                         disks *  RAID chunk size in file system blocks.
-delalloc        (*)     Deferring block allocation until write-out time.
-nodelalloc              Disable delayed allocation. Blocks are allocation
-                        when data is copied from user to page cache.
+
+delalloc        (*)     Defer block allocation until just before ext4
+                        writes out the block(s) in question.  This
+                        allows ext4 to better allocation decisions
+                        more efficiently.
+nodelalloc              Disable delayed allocation.  Blocks are allocated
+                        when the data is copied from userspace to the
+                        page cache, either via the write(2) system call
+                        or when an mmap'ed page which was previously
+                        unallocated is written for the first time.
 
 max_batch_time=usec     Maximum amount of time ext4 should wait for
                         additional filesystem operations to be batch