Merge branch 'linus' into x86/i8259

[sfrench/cifs-2.6.git] / Documentation / filesystems / ext4.txt

diff --git a/Documentation/filesystems/ext4.txt b/Documentation/filesystems/ext4.txt
index 6a4adcae9f9a699d624a0bb114f8e0d5f86161c5..0c5086db835262828edd6b377bee4affb4b6da6f 100644 (file)
--- a/Documentation/filesystems/ext4.txt
+++ b/Documentation/filesystems/ext4.txt
@@ -86,9 +86,21 @@ Alex is working on a new set of patches right now.
 When mounting an ext4 filesystem, the following option are accepted:
 (*) == default
 
-extents                        ext4 will use extents to address file data.  The
+extents                (*)     ext4 will use extents to address file data.  The
                        file system will no longer be mountable by ext3.
 
+noextents              ext4 will not use extents for newly created files
+
+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. This will enable 'journal_checksum'
+                       internally.
+
 journal=update         Update the ext4 file system's journal to the current
                        format.
 
@@ -127,8 +139,16 @@ commit=nrsec       (*)     Ext4 can be told to sync all its data and metadata
                        Setting it to very large values will improve
                        performance.
 
-barrier=1              This enables/disables barriers.  barrier=0 disables
-                       it, barrier=1 enables it.
+barrier=<0|1(*)>       This enables/disables the use of write barriers in
+                       the jbd code.  barrier=0 disables, barrier=1 enables.
+                       This also requires an IO stack which can support
+                       barriers, and if jbd gets an error on a barrier
+                       write, it will disable again with a warning.
+                       Write barriers enforce proper on-disk ordering
+                       of journal commits, making volatile disk write caches
+                       safe to use, at some performance penalty.  If
+                       your disks are battery-backed in one way or another,
+                       disabling barriers may safely improve performance.
 
 orlov          (*)     This enables the new Orlov block allocator. It is
                        enabled by default.
@@ -196,6 +216,12 @@ nobh                       (a) cache disk block mapping information
                        "nobh" option tries to avoid associating buffer
                        heads (supported only for "writeback" mode).
 
+mballoc                (*)     Use the multiple block allocator for block allocation
+nomballoc              disabled multiple block allocator for block allocation.
+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.
 
 Data Mode
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