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-rw-r--r--Documentation/filesystems/ext4.txt12
-rw-r--r--Documentation/filesystems/sysfs-pci.txt1
2 files changed, 11 insertions, 2 deletions
diff --git a/Documentation/filesystems/ext4.txt b/Documentation/filesystems/ext4.txt
index 560f88dc709..0c5086db835 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 5daa2aaec2c..68ef48839c0 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)