2 files changed, 11 insertions, 2 deletions

diff --git a/Documentation/filesystems/ext4.txt b/Documentation/filesystems/ext4.txt
index 560f88dc7090..0c5086db8352 100644
--- a/Documentation/filesystems/ext4.txt
+++ b/Documentation/filesystems/ext4.txt
@@ -139,8 +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.
diff --git a/Documentation/filesystems/sysfs-pci.txt b/Documentation/filesystems/sysfs-pci.txt
index 5daa2aaec2c5..68ef48839c04 100644
--- a/Documentation/filesystems/sysfs-pci.txt
+++ b/Documentation/filesystems/sysfs-pci.txt
@@ -36,6 +36,7 @@ files, each with their own function.
        local_cpus          nearby CPU mask (cpumask, ro)
        resource            PCI resource host addresses (ascii, ro)
        resource0..N        PCI resource N, if present (binary, mmap)
+       resource0_wc..N_wc  PCI WC map resource N, if prefetchable (binary, mmap)
        rom                 PCI ROM resource, if present (binary, ro)
        subsystem_device    PCI subsystem device (ascii, ro)
        subsystem_vendor    PCI subsystem vendor (ascii, ro)