3 files changed, 225 insertions, 46 deletions

diff --git a/Documentation/filesystems/configfs/configfs_example.c b/Documentation/filesystems/configfs/configfs_example.c
index 25151fd5c2c6..039648791701 100644
--- a/Documentation/filesystems/configfs/configfs_example.c
+++ b/Documentation/filesystems/configfs/configfs_example.c
@@ -279,7 +279,7 @@ static struct config_item *simple_children_make_item(struct config_group *group,
 
         simple_child = kzalloc(sizeof(struct simple_child), GFP_KERNEL);
         if (!simple_child)
-                return NULL;
+                return ERR_PTR(-ENOMEM);
 
 
         config_item_init_type_name(&simple_child->item, name,
@@ -366,7 +366,7 @@ static struct config_group *group_children_make_group(struct config_group *group
         simple_children = kzalloc(sizeof(struct simple_children),
                                   GFP_KERNEL);
         if (!simple_children)
-                return NULL;
+                return ERR_PTR(-ENOMEM);
 
 
         config_group_init_type_name(&simple_children->group, name,
diff --git a/Documentation/filesystems/nfs-rdma.txt b/Documentation/filesystems/nfs-rdma.txt
index d0ec45ae4e7d..44bd766f2e5d 100644
--- a/Documentation/filesystems/nfs-rdma.txt
+++ b/Documentation/filesystems/nfs-rdma.txt
@@ -5,7 +5,7 @@
 ################################################################################
 
  Author: NetApp and Open Grid Computing
- Date: April 15, 2008
+ Date: May 29, 2008
 
 Table of Contents
 ~~~~~~~~~~~~~~~~~
@@ -60,16 +60,18 @@ Installation
     The procedures described in this document have been tested with
     distributions from Red Hat's Fedora Project (http://fedora.redhat.com/).
 
-  - Install nfs-utils-1.1.1 or greater on the client
+  - Install nfs-utils-1.1.2 or greater on the client
 
-    An NFS/RDMA mount point can only be obtained by using the mount.nfs
-    command in nfs-utils-1.1.1 or greater. To see which version of mount.nfs
-    you are using, type:
+    An NFS/RDMA mount point can be obtained by using the mount.nfs command in
+    nfs-utils-1.1.2 or greater (nfs-utils-1.1.1 was the first nfs-utils
+    version with support for NFS/RDMA mounts, but for various reasons we
+    recommend using nfs-utils-1.1.2 or greater). To see which version of
+    mount.nfs you are using, type:
 
-    > /sbin/mount.nfs -V
+    $ /sbin/mount.nfs -V
 
-    If the version is less than 1.1.1 or the command does not exist,
-    then you will need to install the latest version of nfs-utils.
+    If the version is less than 1.1.2 or the command does not exist,
+    you should install the latest version of nfs-utils.
 
     Download the latest package from:
 
@@ -77,22 +79,33 @@ Installation
 
     Uncompress the package and follow the installation instructions.
 
-    If you will not be using GSS and NFSv4, the installation process
-    can be simplified by disabling these features when running configure:
+    If you will not need the idmapper and gssd executables (you do not need
+    these to create an NFS/RDMA enabled mount command), the installation
+    process can be simplified by disabling these features when running
+    configure:
 
-    > ./configure --disable-gss --disable-nfsv4
+    $ ./configure --disable-gss --disable-nfsv4
 
-    For more information on this see the package's README and INSTALL files.
+    To build nfs-utils you will need the tcp_wrappers package installed. For
+    more information on this see the package's README and INSTALL files.
 
     After building the nfs-utils package, there will be a mount.nfs binary in
     the utils/mount directory. This binary can be used to initiate NFS v2, v3,
-    or v4 mounts. To initiate a v4 mount, the binary must be called mount.nfs4.
-    The standard technique is to create a symlink called mount.nfs4 to mount.nfs.
+    or v4 mounts. To initiate a v4 mount, the binary must be called
+    mount.nfs4.  The standard technique is to create a symlink called
+    mount.nfs4 to mount.nfs.
 
-    NOTE: mount.nfs and therefore nfs-utils-1.1.1 or greater is only needed
+    This mount.nfs binary should be installed at /sbin/mount.nfs as follows:
+
+    $ sudo cp utils/mount/mount.nfs /sbin/mount.nfs
+
+    In this location, mount.nfs will be invoked automatically for NFS mounts
+    by the system mount commmand.
+
+    NOTE: mount.nfs and therefore nfs-utils-1.1.2 or greater is only needed
     on the NFS client machine. You do not need this specific version of
     nfs-utils on the server. Furthermore, only the mount.nfs command from
-    nfs-utils-1.1.1 is needed on the client.
+    nfs-utils-1.1.2 is needed on the client.
 
   - Install a Linux kernel with NFS/RDMA
 
@@ -156,8 +169,8 @@ Check RDMA and NFS Setup
     this time. For example, if you are using a Mellanox Tavor/Sinai/Arbel
     card:
 
-    > modprobe ib_mthca
-    > modprobe ib_ipoib
+    $ modprobe ib_mthca
+    $ modprobe ib_ipoib
 
     If you are using InfiniBand, make sure there is a Subnet Manager (SM)
     running on the network. If your IB switch has an embedded SM, you can
@@ -166,7 +179,7 @@ Check RDMA and NFS Setup
 
     If an SM is running on your network, you should see the following:
 
-    > cat /sys/class/infiniband/driverX/ports/1/state
+    $ cat /sys/class/infiniband/driverX/ports/1/state
     4: ACTIVE
 
     where driverX is mthca0, ipath5, ehca3, etc.
@@ -174,10 +187,10 @@ Check RDMA and NFS Setup
     To further test the InfiniBand software stack, use IPoIB (this
     assumes you have two IB hosts named host1 and host2):
 
-    host1> ifconfig ib0 a.b.c.x
-    host2> ifconfig ib0 a.b.c.y
-    host1> ping a.b.c.y
-    host2> ping a.b.c.x
+    host1$ ifconfig ib0 a.b.c.x
+    host2$ ifconfig ib0 a.b.c.y
+    host1$ ping a.b.c.y
+    host2$ ping a.b.c.x
 
     For other device types, follow the appropriate procedures.
 
@@ -202,11 +215,11 @@ NFS/RDMA Setup
     /vol0   192.168.0.47(fsid=0,rw,async,insecure,no_root_squash)
     /vol0   192.168.0.0/255.255.255.0(fsid=0,rw,async,insecure,no_root_squash)
 
-    The IP address(es) is(are) the client's IPoIB address for an InfiniBand HCA or the
-    cleint's iWARP address(es) for an RNIC.
+    The IP address(es) is(are) the client's IPoIB address for an InfiniBand
+    HCA or the cleint's iWARP address(es) for an RNIC.
 
-    NOTE: The "insecure" option must be used because the NFS/RDMA client does not
-    use a reserved port.
+    NOTE: The "insecure" option must be used because the NFS/RDMA client does
+    not use a reserved port.
 
  Each time a machine boots:
 
@@ -214,43 +227,45 @@ NFS/RDMA Setup
 
     For InfiniBand using a Mellanox adapter:
 
-    > modprobe ib_mthca
-    > modprobe ib_ipoib
-    > ifconfig ib0 a.b.c.d
+    $ modprobe ib_mthca
+    $ modprobe ib_ipoib
+    $ ifconfig ib0 a.b.c.d
 
     NOTE: use unique addresses for the client and server
 
   - Start the NFS server
 
-    If the NFS/RDMA server was built as a module (CONFIG_SUNRPC_XPRT_RDMA=m in kernel config),
-    load the RDMA transport module:
+    If the NFS/RDMA server was built as a module (CONFIG_SUNRPC_XPRT_RDMA=m in
+    kernel config), load the RDMA transport module:
 
-    > modprobe svcrdma
+    $ modprobe svcrdma
 
-    Regardless of how the server was built (module or built-in), start the server:
+    Regardless of how the server was built (module or built-in), start the
+    server:
 
-    > /etc/init.d/nfs start
+    $ /etc/init.d/nfs start
 
     or
 
-    > service nfs start
+    $ service nfs start
 
     Instruct the server to listen on the RDMA transport:
 
-    > echo rdma 2050 > /proc/fs/nfsd/portlist
+    $ echo rdma 2050 > /proc/fs/nfsd/portlist
 
   - On the client system
 
-    If the NFS/RDMA client was built as a module (CONFIG_SUNRPC_XPRT_RDMA=m in kernel config),
-    load the RDMA client module:
+    If the NFS/RDMA client was built as a module (CONFIG_SUNRPC_XPRT_RDMA=m in
+    kernel config), load the RDMA client module:
 
-    > modprobe xprtrdma.ko
+    $ modprobe xprtrdma.ko
 
-    Regardless of how the client was built (module or built-in), issue the mount.nfs command:
+    Regardless of how the client was built (module or built-in), use this
+    command to mount the NFS/RDMA server:
 
-    > /path/to/your/mount.nfs <IPoIB-server-name-or-address>:/<export> /mnt -i -o rdma,port=2050
+    $ mount -o rdma,port=2050 <IPoIB-server-name-or-address>:/<export> /mnt
 
-    To verify that the mount is using RDMA, run "cat /proc/mounts" and check the
-    "proto" field for the given mount.
+    To verify that the mount is using RDMA, run "cat /proc/mounts" and check
+    the "proto" field for the given mount.
 
   Congratulations! You're using NFS/RDMA!
diff --git a/Documentation/filesystems/ubifs.txt b/Documentation/filesystems/ubifs.txt
new file mode 100644
index 000000000000..540e9e7f59c5
--- /dev/null
+++ b/Documentation/filesystems/ubifs.txt
@@ -0,0 +1,164 @@
+Introduction
+=============
+
+UBIFS file-system stands for UBI File System. UBI stands for "Unsorted
+Block Images". UBIFS is a flash file system, which means it is designed
+to work with flash devices. It is important to understand, that UBIFS
+is completely different to any traditional file-system in Linux, like
+Ext2, XFS, JFS, etc. UBIFS represents a separate class of file-systems
+which work with MTD devices, not block devices. The other Linux
+file-system of this class is JFFS2.
+
+To make it more clear, here is a small comparison of MTD devices and
+block devices.
+
+1 MTD devices represent flash devices and they consist of eraseblocks of
+  rather large size, typically about 128KiB. Block devices consist of
+  small blocks, typically 512 bytes.
+2 MTD devices support 3 main operations - read from some offset within an
+  eraseblock, write to some offset within an eraseblock, and erase a whole
+  eraseblock. Block  devices support 2 main operations - read a whole
+  block and write a whole block.
+3 The whole eraseblock has to be erased before it becomes possible to
+  re-write its contents. Blocks may be just re-written.
+4 Eraseblocks become worn out after some number of erase cycles -
+  typically 100K-1G for SLC NAND and NOR flashes, and 1K-10K for MLC
+  NAND flashes. Blocks do not have the wear-out property.
+5 Eraseblocks may become bad (only on NAND flashes) and software should
+  deal with this. Blocks on hard drives typically do not become bad,
+  because hardware has mechanisms to substitute bad blocks, at least in
+  modern LBA disks.
+
+It should be quite obvious why UBIFS is very different to traditional
+file-systems.
+
+UBIFS works on top of UBI. UBI is a separate software layer which may be
+found in drivers/mtd/ubi. UBI is basically a volume management and
+wear-leveling layer. It provides so called UBI volumes which is a higher
+level abstraction than a MTD device. The programming model of UBI devices
+is very similar to MTD devices - they still consist of large eraseblocks,
+they have read/write/erase operations, but UBI devices are devoid of
+limitations like wear and bad blocks (items 4 and 5 in the above list).
+
+In a sense, UBIFS is a next generation of JFFS2 file-system, but it is
+very different and incompatible to JFFS2. The following are the main
+differences.
+
+* JFFS2 works on top of MTD devices, UBIFS depends on UBI and works on
+  top of UBI volumes.
+* JFFS2 does not have on-media index and has to build it while mounting,
+  which requires full media scan. UBIFS maintains the FS indexing
+  information on the flash media and does not require full media scan,
+  so it mounts many times faster than JFFS2.
+* JFFS2 is a write-through file-system, while UBIFS supports write-back,
+  which makes UBIFS much faster on writes.
+
+Similarly to JFFS2, UBIFS supports on-the-flight compression which makes
+it possible to fit quite a lot of data to the flash.
+
+Similarly to JFFS2, UBIFS is tolerant of unclean reboots and power-cuts.
+It does not need stuff like ckfs.ext2. UBIFS automatically replays its
+journal and recovers from crashes, ensuring that the on-flash data
+structures are consistent.
+
+UBIFS scales logarithmically (most of the data structures it uses are
+trees), so the mount time and memory consumption do not linearly depend
+on the flash size, like in case of JFFS2. This is because UBIFS
+maintains the FS index on the flash media. However, UBIFS depends on
+UBI, which scales linearly. So overall UBI/UBIFS stack scales linearly.
+Nevertheless, UBI/UBIFS scales considerably better than JFFS2.
+
+The authors of UBIFS believe, that it is possible to develop UBI2 which
+would scale logarithmically as well. UBI2 would support the same API as UBI,
+but it would be binary incompatible to UBI. So UBIFS would not need to be
+changed to use UBI2
+
+
+Mount options
+=============
+
+(*) == default.
+
+norm_unmount (*)        commit on unmount; the journal is committed
+                        when the file-system is unmounted so that the
+                        next mount does not have to replay the journal
+                        and it becomes very fast;
+fast_unmount            do not commit on unmount; this option makes
+                        unmount faster, but the next mount slower
+                        because of the need to replay the journal.
+
+
+Quick usage instructions
+========================
+
+The UBI volume to mount is specified using "ubiX_Y" or "ubiX:NAME" syntax,
+where "X" is UBI device number, "Y" is UBI volume number, and "NAME" is
+UBI volume name.
+
+Mount volume 0 on UBI device 0 to /mnt/ubifs:
+$ mount -t ubifs ubi0_0 /mnt/ubifs
+
+Mount "rootfs" volume of UBI device 0 to /mnt/ubifs ("rootfs" is volume
+name):
+$ mount -t ubifs ubi0:rootfs /mnt/ubifs
+
+The following is an example of the kernel boot arguments to attach mtd0
+to UBI and mount volume "rootfs":
+ubi.mtd=0 root=ubi0:rootfs rootfstype=ubifs
+
+
+Module Parameters for Debugging
+===============================
+
+When UBIFS has been compiled with debugging enabled, there are 3 module
+parameters that are available to control aspects of testing and debugging.
+The parameters are unsigned integers where each bit controls an option.
+The parameters are:
+
+debug_msgs      Selects which debug messages to display, as follows:
+
+                Message Type                            Flag value
+
+                General messages                        1
+                Journal messages                        2
+                Mount messages                          4
+                Commit messages                         8
+                LEB search messages                     16
+                Budgeting messages                      32
+                Garbage collection messages             64
+                Tree Node Cache (TNC) messages          128
+                LEB properties (lprops) messages        256
+                Input/output messages                   512
+                Log messages                            1024
+                Scan messages                           2048
+                Recovery messages                       4096
+
+debug_chks      Selects extra checks that UBIFS can do while running:
+
+                Check                                   Flag value
+
+                General checks                          1
+                Check Tree Node Cache (TNC)             2
+                Check indexing tree size                4
+                Check orphan area                       8
+                Check old indexing tree                 16
+                Check LEB properties (lprops)           32
+                Check leaf nodes and inodes             64
+
+debug_tsts      Selects a mode of testing, as follows:
+
+                Test mode                               Flag value
+
+                Force in-the-gaps method                2
+                Failure mode for recovery testing       4
+
+For example, set debug_msgs to 5 to display General messages and Mount
+messages.
+
+
+References
+==========
+
+UBIFS documentation and FAQ/HOWTO at the MTD web site:
+http://www.linux-mtd.infradead.org/doc/ubifs.html
+http://www.linux-mtd.infradead.org/faq/ubifs.html