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-rw-r--r--Documentation/ABI/testing/sysfs-bus-usb2
-rw-r--r--Documentation/DMA-API-HOWTO.txt (renamed from Documentation/PCI/PCI-DMA-mapping.txt)0
-rw-r--r--Documentation/DocBook/tracepoint.tmpl13
-rw-r--r--Documentation/RCU/NMI-RCU.txt39
-rw-r--r--Documentation/RCU/checklist.txt7
-rw-r--r--Documentation/RCU/lockdep.txt28
-rw-r--r--Documentation/RCU/whatisRCU.txt6
-rw-r--r--Documentation/block/biodoc.txt4
-rw-r--r--Documentation/circular-buffers.txt234
-rw-r--r--Documentation/connector/cn_test.c1
-rw-r--r--Documentation/fb/efifb.txt (renamed from Documentation/fb/imacfb.txt)14
-rw-r--r--Documentation/feature-removal-schedule.txt7
-rw-r--r--Documentation/filesystems/00-INDEX2
-rw-r--r--Documentation/filesystems/9p.txt18
-rw-r--r--Documentation/filesystems/ceph.txt140
-rw-r--r--Documentation/filesystems/tmpfs.txt6
-rw-r--r--Documentation/input/multi-touch-protocol.txt23
-rw-r--r--Documentation/ioctl/ioctl-number.txt1
-rw-r--r--Documentation/kernel-parameters.txt9
-rw-r--r--Documentation/kobject.txt60
-rw-r--r--Documentation/memory-barriers.txt20
-rw-r--r--Documentation/networking/Makefile2
-rw-r--r--Documentation/networking/stmmac.txt143
-rw-r--r--Documentation/networking/timestamping.txt76
-rw-r--r--Documentation/networking/timestamping/Makefile11
-rw-r--r--Documentation/networking/timestamping/timestamping.c10
-rw-r--r--Documentation/powerpc/dts-bindings/fsl/cpm_qe/qe.txt54
-rw-r--r--Documentation/sound/alsa/HD-Audio.txt16
-rw-r--r--Documentation/volatile-considered-harmful.txt6
-rw-r--r--Documentation/watchdog/src/watchdog-simple.c3
-rw-r--r--Documentation/watchdog/src/watchdog-test.c8
-rw-r--r--Documentation/watchdog/watchdog-api.txt5
32 files changed, 846 insertions, 122 deletions
diff --git a/Documentation/ABI/testing/sysfs-bus-usb b/Documentation/ABI/testing/sysfs-bus-usb
index a986e9bbba3..bcebb9eaedc 100644
--- a/Documentation/ABI/testing/sysfs-bus-usb
+++ b/Documentation/ABI/testing/sysfs-bus-usb
@@ -160,7 +160,7 @@ Description:
match the driver to the device. For example:
# echo "046d c315" > /sys/bus/usb/drivers/foo/remove_id
-What: /sys/bus/usb/device/.../avoid_reset
+What: /sys/bus/usb/device/.../avoid_reset_quirk
Date: December 2009
Contact: Oliver Neukum <oliver@neukum.org>
Description:
diff --git a/Documentation/PCI/PCI-DMA-mapping.txt b/Documentation/DMA-API-HOWTO.txt
index 52618ab069a..52618ab069a 100644
--- a/Documentation/PCI/PCI-DMA-mapping.txt
+++ b/Documentation/DMA-API-HOWTO.txt
diff --git a/Documentation/DocBook/tracepoint.tmpl b/Documentation/DocBook/tracepoint.tmpl
index 8bca1d5cec0..e8473eae2a2 100644
--- a/Documentation/DocBook/tracepoint.tmpl
+++ b/Documentation/DocBook/tracepoint.tmpl
@@ -16,6 +16,15 @@
</address>
</affiliation>
</author>
+ <author>
+ <firstname>William</firstname>
+ <surname>Cohen</surname>
+ <affiliation>
+ <address>
+ <email>wcohen@redhat.com</email>
+ </address>
+ </affiliation>
+ </author>
</authorgroup>
<legalnotice>
@@ -91,4 +100,8 @@
!Iinclude/trace/events/signal.h
</chapter>
+ <chapter id="block">
+ <title>Block IO</title>
+!Iinclude/trace/events/block.h
+ </chapter>
</book>
diff --git a/Documentation/RCU/NMI-RCU.txt b/Documentation/RCU/NMI-RCU.txt
index a6d32e65d22..a8536cb8809 100644
--- a/Documentation/RCU/NMI-RCU.txt
+++ b/Documentation/RCU/NMI-RCU.txt
@@ -34,7 +34,7 @@ NMI handler.
cpu = smp_processor_id();
++nmi_count(cpu);
- if (!rcu_dereference(nmi_callback)(regs, cpu))
+ if (!rcu_dereference_sched(nmi_callback)(regs, cpu))
default_do_nmi(regs);
nmi_exit();
@@ -47,12 +47,13 @@ function pointer. If this handler returns zero, do_nmi() invokes the
default_do_nmi() function to handle a machine-specific NMI. Finally,
preemption is restored.
-Strictly speaking, rcu_dereference() is not needed, since this code runs
-only on i386, which does not need rcu_dereference() anyway. However,
-it is a good documentation aid, particularly for anyone attempting to
-do something similar on Alpha.
+In theory, rcu_dereference_sched() is not needed, since this code runs
+only on i386, which in theory does not need rcu_dereference_sched()
+anyway. However, in practice it is a good documentation aid, particularly
+for anyone attempting to do something similar on Alpha or on systems
+with aggressive optimizing compilers.
-Quick Quiz: Why might the rcu_dereference() be necessary on Alpha,
+Quick Quiz: Why might the rcu_dereference_sched() be necessary on Alpha,
given that the code referenced by the pointer is read-only?
@@ -99,17 +100,21 @@ invoke irq_enter() and irq_exit() on NMI entry and exit, respectively.
Answer to Quick Quiz
- Why might the rcu_dereference() be necessary on Alpha, given
+ Why might the rcu_dereference_sched() be necessary on Alpha, given
that the code referenced by the pointer is read-only?
Answer: The caller to set_nmi_callback() might well have
- initialized some data that is to be used by the
- new NMI handler. In this case, the rcu_dereference()
- would be needed, because otherwise a CPU that received
- an NMI just after the new handler was set might see
- the pointer to the new NMI handler, but the old
- pre-initialized version of the handler's data.
-
- More important, the rcu_dereference() makes it clear
- to someone reading the code that the pointer is being
- protected by RCU.
+ initialized some data that is to be used by the new NMI
+ handler. In this case, the rcu_dereference_sched() would
+ be needed, because otherwise a CPU that received an NMI
+ just after the new handler was set might see the pointer
+ to the new NMI handler, but the old pre-initialized
+ version of the handler's data.
+
+ This same sad story can happen on other CPUs when using
+ a compiler with aggressive pointer-value speculation
+ optimizations.
+
+ More important, the rcu_dereference_sched() makes it
+ clear to someone reading the code that the pointer is
+ being protected by RCU-sched.
diff --git a/Documentation/RCU/checklist.txt b/Documentation/RCU/checklist.txt
index cbc180f9019..790d1a81237 100644
--- a/Documentation/RCU/checklist.txt
+++ b/Documentation/RCU/checklist.txt
@@ -260,7 +260,8 @@ over a rather long period of time, but improvements are always welcome!
The reason that it is permissible to use RCU list-traversal
primitives when the update-side lock is held is that doing so
can be quite helpful in reducing code bloat when common code is
- shared between readers and updaters.
+ shared between readers and updaters. Additional primitives
+ are provided for this case, as discussed in lockdep.txt.
10. Conversely, if you are in an RCU read-side critical section,
and you don't hold the appropriate update-side lock, you -must-
@@ -344,8 +345,8 @@ over a rather long period of time, but improvements are always welcome!
requiring SRCU's read-side deadlock immunity or low read-side
realtime latency.
- Note that, rcu_assign_pointer() and rcu_dereference() relate to
- SRCU just as they do to other forms of RCU.
+ Note that, rcu_assign_pointer() relates to SRCU just as they do
+ to other forms of RCU.
15. The whole point of call_rcu(), synchronize_rcu(), and friends
is to wait until all pre-existing readers have finished before
diff --git a/Documentation/RCU/lockdep.txt b/Documentation/RCU/lockdep.txt
index fe24b58627b..d7a49b2f699 100644
--- a/Documentation/RCU/lockdep.txt
+++ b/Documentation/RCU/lockdep.txt
@@ -32,9 +32,20 @@ checking of rcu_dereference() primitives:
srcu_dereference(p, sp):
Check for SRCU read-side critical section.
rcu_dereference_check(p, c):
- Use explicit check expression "c".
+ Use explicit check expression "c". This is useful in
+ code that is invoked by both readers and updaters.
rcu_dereference_raw(p)
Don't check. (Use sparingly, if at all.)
+ rcu_dereference_protected(p, c):
+ Use explicit check expression "c", and omit all barriers
+ and compiler constraints. This is useful when the data
+ structure cannot change, for example, in code that is
+ invoked only by updaters.
+ rcu_access_pointer(p):
+ Return the value of the pointer and omit all barriers,
+ but retain the compiler constraints that prevent duplicating
+ or coalescsing. This is useful when when testing the
+ value of the pointer itself, for example, against NULL.
The rcu_dereference_check() check expression can be any boolean
expression, but would normally include one of the rcu_read_lock_held()
@@ -59,7 +70,20 @@ In case (1), the pointer is picked up in an RCU-safe manner for vanilla
RCU read-side critical sections, in case (2) the ->file_lock prevents
any change from taking place, and finally, in case (3) the current task
is the only task accessing the file_struct, again preventing any change
-from taking place.
+from taking place. If the above statement was invoked only from updater
+code, it could instead be written as follows:
+
+ file = rcu_dereference_protected(fdt->fd[fd],
+ lockdep_is_held(&files->file_lock) ||
+ atomic_read(&files->count) == 1);
+
+This would verify cases #2 and #3 above, and furthermore lockdep would
+complain if this was used in an RCU read-side critical section unless one
+of these two cases held. Because rcu_dereference_protected() omits all
+barriers and compiler constraints, it generates better code than do the
+other flavors of rcu_dereference(). On the other hand, it is illegal
+to use rcu_dereference_protected() if either the RCU-protected pointer
+or the RCU-protected data that it points to can change concurrently.
There are currently only "universal" versions of the rcu_assign_pointer()
and RCU list-/tree-traversal primitives, which do not (yet) check for
diff --git a/Documentation/RCU/whatisRCU.txt b/Documentation/RCU/whatisRCU.txt
index 1dc00ee9716..cfaac34c455 100644
--- a/Documentation/RCU/whatisRCU.txt
+++ b/Documentation/RCU/whatisRCU.txt
@@ -840,6 +840,12 @@ SRCU: Initialization/cleanup
init_srcu_struct
cleanup_srcu_struct
+All: lockdep-checked RCU-protected pointer access
+
+ rcu_dereference_check
+ rcu_dereference_protected
+ rcu_access_pointer
+
See the comment headers in the source code (or the docbook generated
from them) for more information.
diff --git a/Documentation/block/biodoc.txt b/Documentation/block/biodoc.txt
index 6fab97ea7e6..508b5b2b028 100644
--- a/Documentation/block/biodoc.txt
+++ b/Documentation/block/biodoc.txt
@@ -1162,8 +1162,8 @@ where a driver received a request ala this before:
As mentioned, there is no virtual mapping of a bio. For DMA, this is
not a problem as the driver probably never will need a virtual mapping.
-Instead it needs a bus mapping (pci_map_page for a single segment or
-use blk_rq_map_sg for scatter gather) to be able to ship it to the driver. For
+Instead it needs a bus mapping (dma_map_page for a single segment or
+use dma_map_sg for scatter gather) to be able to ship it to the driver. For
PIO drivers (or drivers that need to revert to PIO transfer once in a
while (IDE for example)), where the CPU is doing the actual data
transfer a virtual mapping is needed. If the driver supports highmem I/O,
diff --git a/Documentation/circular-buffers.txt b/Documentation/circular-buffers.txt
new file mode 100644
index 00000000000..8117e5bf606
--- /dev/null
+++ b/Documentation/circular-buffers.txt
@@ -0,0 +1,234 @@
+ ================
+ CIRCULAR BUFFERS
+ ================
+
+By: David Howells <dhowells@redhat.com>
+ Paul E. McKenney <paulmck@linux.vnet.ibm.com>
+
+
+Linux provides a number of features that can be used to implement circular
+buffering. There are two sets of such features:
+
+ (1) Convenience functions for determining information about power-of-2 sized
+ buffers.
+
+ (2) Memory barriers for when the producer and the consumer of objects in the
+ buffer don't want to share a lock.
+
+To use these facilities, as discussed below, there needs to be just one
+producer and just one consumer. It is possible to handle multiple producers by
+serialising them, and to handle multiple consumers by serialising them.
+
+
+Contents:
+
+ (*) What is a circular buffer?
+
+ (*) Measuring power-of-2 buffers.
+
+ (*) Using memory barriers with circular buffers.
+ - The producer.
+ - The consumer.
+
+
+==========================
+WHAT IS A CIRCULAR BUFFER?
+==========================
+
+First of all, what is a circular buffer? A circular buffer is a buffer of
+fixed, finite size into which there are two indices:
+
+ (1) A 'head' index - the point at which the producer inserts items into the
+ buffer.
+
+ (2) A 'tail' index - the point at which the consumer finds the next item in
+ the buffer.
+
+Typically when the tail pointer is equal to the head pointer, the buffer is
+empty; and the buffer is full when the head pointer is one less than the tail
+pointer.
+
+The head index is incremented when items are added, and the tail index when
+items are removed. The tail index should never jump the head index, and both
+indices should be wrapped to 0 when they reach the end of the buffer, thus
+allowing an infinite amount of data to flow through the buffer.
+
+Typically, items will all be of the same unit size, but this isn't strictly
+required to use the techniques below. The indices can be increased by more
+than 1 if multiple items or variable-sized items are to be included in the
+buffer, provided that neither index overtakes the other. The implementer must
+be careful, however, as a region more than one unit in size may wrap the end of
+the buffer and be broken into two segments.
+
+
+============================
+MEASURING POWER-OF-2 BUFFERS
+============================
+
+Calculation of the occupancy or the remaining capacity of an arbitrarily sized
+circular buffer would normally be a slow operation, requiring the use of a
+modulus (divide) instruction. However, if the buffer is of a power-of-2 size,
+then a much quicker bitwise-AND instruction can be used instead.
+
+Linux provides a set of macros for handling power-of-2 circular buffers. These
+can be made use of by:
+
+ #include <linux/circ_buf.h>
+
+The macros are:
+
+ (*) Measure the remaining capacity of a buffer:
+
+ CIRC_SPACE(head_index, tail_index, buffer_size);
+
+ This returns the amount of space left in the buffer[1] into which items
+ can be inserted.
+
+
+ (*) Measure the maximum consecutive immediate space in a buffer:
+
+ CIRC_SPACE_TO_END(head_index, tail_index, buffer_size);
+
+ This returns the amount of consecutive space left in the buffer[1] into
+ which items can be immediately inserted without having to wrap back to the
+ beginning of the buffer.
+
+
+ (*) Measure the occupancy of a buffer:
+
+ CIRC_CNT(head_index, tail_index, buffer_size);
+
+ This returns the number of items currently occupying a buffer[2].
+
+
+ (*) Measure the non-wrapping occupancy of a buffer:
+
+ CIRC_CNT_TO_END(head_index, tail_index, buffer_size);
+
+ This returns the number of consecutive items[2] that can be extracted from
+ the buffer without having to wrap back to the beginning of the buffer.
+
+
+Each of these macros will nominally return a value between 0 and buffer_size-1,
+however:
+
+ [1] CIRC_SPACE*() are intended to be used in the producer. To the producer
+ they will return a lower bound as the producer controls the head index,
+ but the consumer may still be depleting the buffer on another CPU and
+ moving the tail index.
+
+ To the consumer it will show an upper bound as the producer may be busy
+ depleting the space.
+
+ [2] CIRC_CNT*() are intended to be used in the consumer. To the consumer they
+ will return a lower bound as the consumer controls the tail index, but the
+ producer may still be filling the buffer on another CPU and moving the
+ head index.
+
+ To the producer it will show an upper bound as the consumer may be busy
+ emptying the buffer.
+
+ [3] To a third party, the order in which the writes to the indices by the
+ producer and consumer become visible cannot be guaranteed as they are
+ independent and may be made on different CPUs - so the result in such a
+ situation will merely be a guess, and may even be negative.
+
+
+===========================================
+USING MEMORY BARRIERS WITH CIRCULAR BUFFERS
+===========================================
+
+By using memory barriers in conjunction with circular buffers, you can avoid
+the need to:
+
+ (1) use a single lock to govern access to both ends of the buffer, thus
+ allowing the buffer to be filled and emptied at the same time; and
+
+ (2) use atomic counter operations.
+
+There are two sides to this: the producer that fills the buffer, and the
+consumer that empties it. Only one thing should be filling a buffer at any one
+time, and only one thing should be emptying a buffer at any one time, but the
+two sides can operate simultaneously.
+
+
+THE PRODUCER
+------------
+
+The producer will look something like this:
+
+ spin_lock(&producer_lock);
+
+ unsigned long head = buffer->head;
+ unsigned long tail = ACCESS_ONCE(buffer->tail);
+
+ if (CIRC_SPACE(head, tail, buffer->size) >= 1) {
+ /* insert one item into the buffer */
+ struct item *item = buffer[head];
+
+ produce_item(item);
+
+ smp_wmb(); /* commit the item before incrementing the head */
+
+ buffer->head = (head + 1) & (buffer->size - 1);
+
+ /* wake_up() will make sure that the head is committed before
+ * waking anyone up */
+ wake_up(consumer);
+ }
+
+ spin_unlock(&producer_lock);
+
+This will instruct the CPU that the contents of the new item must be written
+before the head index makes it available to the consumer and then instructs the
+CPU that the revised head index must be written before the consumer is woken.
+
+Note that wake_up() doesn't have to be the exact mechanism used, but whatever
+is used must guarantee a (write) memory barrier between the update of the head
+index and the change of state of the consumer, if a change of state occurs.
+
+
+THE CONSUMER
+------------
+
+The consumer will look something like this:
+
+ spin_lock(&consumer_lock);
+
+ unsigned long head = ACCESS_ONCE(buffer->head);
+ unsigned long tail = buffer->tail;
+
+ if (CIRC_CNT(head, tail, buffer->size) >= 1) {
+ /* read index before reading contents at that index */
+ smp_read_barrier_depends();
+
+ /* extract one item from the buffer */
+ struct item *item = buffer[tail];
+
+ consume_item(item);
+
+ smp_mb(); /* finish reading descriptor before incrementing tail */
+
+ buffer->tail = (tail + 1) & (buffer->size - 1);
+ }
+
+ spin_unlock(&consumer_lock);
+
+This will instruct the CPU to make sure the index is up to date before reading
+the new item, and then it shall make sure the CPU has finished reading the item
+before it writes the new tail pointer, which will erase the item.
+
+
+Note the use of ACCESS_ONCE() in both algorithms to read the opposition index.
+This prevents the compiler from discarding and reloading its cached value -
+which some compilers will do across smp_read_barrier_depends(). This isn't
+strictly needed if you can be sure that the opposition index will _only_ be
+used the once.
+
+
+===============
+FURTHER READING
+===============
+
+See also Documentation/memory-barriers.txt for a description of Linux's memory
+barrier facilities.
diff --git a/Documentation/connector/cn_test.c b/Documentation/connector/cn_test.c
index b07add3467f..7764594778d 100644
--- a/Documentation/connector/cn_test.c
+++ b/Documentation/connector/cn_test.c
@@ -25,6 +25,7 @@
#include <linux/module.h>
#include <linux/moduleparam.h>
#include <linux/skbuff.h>
+#include <linux/slab.h>
#include <linux/timer.h>
#include <linux/connector.h>
diff --git a/Documentation/fb/imacfb.txt b/Documentation/fb/efifb.txt
index 316ec9bb7de..a59916c29b3 100644
--- a/Documentation/fb/imacfb.txt
+++ b/Documentation/fb/efifb.txt
@@ -1,9 +1,9 @@
-What is imacfb?
+What is efifb?
===============
This is a generic EFI platform driver for Intel based Apple computers.
-Imacfb is only for EFI booted Intel Macs.
+efifb is only for EFI booted Intel Macs.
Supported Hardware
==================
@@ -16,16 +16,16 @@ MacMini
How to use it?
==============
-Imacfb does not have any kind of autodetection of your machine.
+efifb does not have any kind of autodetection of your machine.
You have to add the following kernel parameters in your elilo.conf:
Macbook :
- video=imacfb:macbook
+ video=efifb:macbook
MacMini :
- video=imacfb:mini
+ video=efifb:mini
Macbook Pro 15", iMac 17" :
- video=imacfb:i17
+ video=efifb:i17
Macbook Pro 17", iMac 20" :
- video=imacfb:i20
+ video=efifb:i20
--
Edgar Hucek <gimli@dark-green.com>
diff --git a/Documentation/feature-removal-schedule.txt b/Documentation/feature-removal-schedule.txt
index a5cc0db63d7..ed511af0f79 100644
--- a/Documentation/feature-removal-schedule.txt
+++ b/Documentation/feature-removal-schedule.txt
@@ -582,3 +582,10 @@ Why: The paravirt mmu host support is slower than non-paravirt mmu, both
Who: Avi Kivity <avi@redhat.com>
----------------------------
+
+What: "acpi=ht" boot option
+When: 2.6.35
+Why: Useful in 2003, implementation is a hack.
+ Generally invoked by accident today.
+ Seen as doing more harm than good.
+Who: Len Brown <len.brown@intel.com>
diff --git a/Documentation/filesystems/00-INDEX b/Documentation/filesystems/00-INDEX
index 3bae418c6ad..4303614b5ad 100644
--- a/Documentation/filesystems/00-INDEX
+++ b/Documentation/filesystems/00-INDEX
@@ -16,6 +16,8 @@ befs.txt
- information about the BeOS filesystem for Linux.
bfs.txt
- info for the SCO UnixWare Boot Filesystem (BFS).
+ceph.txt
+ - info for the Ceph Distributed File System
cifs.txt
- description of the CIFS filesystem.
coda.txt
diff --git a/Documentation/filesystems/9p.txt b/Documentation/filesystems/9p.txt
index 57e0b80a527..c0236e753bc 100644
--- a/Documentation/filesystems/9p.txt
+++ b/Documentation/filesystems/9p.txt
@@ -37,6 +37,15 @@ For Plan 9 From User Space applications (http://swtch.com/plan9)
mount -t 9p `namespace`/acme /mnt/9 -o trans=unix,uname=$USER
+For server running on QEMU host with virtio transport:
+
+ mount -t 9p -o trans=virtio <mount_tag> /mnt/9
+
+where mount_tag is the tag associated by the server to each of the exported
+mount points. Each 9P export is seen by the client as a virtio device with an
+associated "mount_tag" property. Available mount tags can be
+seen by reading /sys/bus/virtio/drivers/9pnet_virtio/virtio<n>/mount_tag files.
+
OPTIONS
=======
@@ -47,7 +56,7 @@ OPTIONS
fd - used passed file descriptors for connection
(see rfdno and wfdno)
virtio - connect to the next virtio channel available
- (from lguest or KVM with trans_virtio module)
+ (from QEMU with trans_virtio module)
rdma - connect to a specified RDMA channel
uname=name user name to attempt mount as on the remote server. The
@@ -85,7 +94,12 @@ OPTIONS
port=n port to connect to on the remote server
- noextend force legacy mode (no 9p2000.u semantics)
+ noextend force legacy mode (no 9p2000.u or 9p2000.L semantics)
+
+ version=name Select 9P protocol version. Valid options are:
+ 9p2000 - Legacy mode (same as noextend)
+ 9p2000.u - Use 9P2000.u protocol
+ 9p2000.L - Use 9P2000.L protocol
dfltuid attempt to mount as a particular uid
diff --git a/Documentation/filesystems/ceph.txt b/Documentation/filesystems/ceph.txt
new file mode 100644
index 00000000000..0660c9f5dee
--- /dev/null
+++ b/Documentation/filesystems/ceph.txt
@@ -0,0 +1,140 @@
+Ceph Distributed File System
+============================
+
+Ceph is a distributed network file system designed to provide good
+performance, reliability, and scalability.
+
+Basic features include:
+
+ * POSIX semantics
+ * Seamless scaling from 1 to many thousands of nodes
+ * High availability and reliability. No single point of failure.
+ * N-way replication of data across storage nodes
+ * Fast recovery from node failures
+ * Automatic rebalancing of data on node addition/removal
+ * Easy deployment: most FS components are userspace daemons
+
+Also,
+ * Flexible snapshots (on any directory)
+ * Recursive accounting (nested files, directories, bytes)
+
+In contrast to cluster filesystems like GFS, OCFS2, and GPFS that rely
+on symmetric access by all clients to shared block devices, Ceph
+separates data and metadata management into independent server
+clusters, similar to Lustre. Unlike Lustre, however, metadata and
+storage nodes run entirely as user space daemons. Storage nodes
+utilize btrfs to store data objects, leveraging its advanced features
+(checksumming, metadata replication, etc.). File data is striped
+across storage nodes in large chunks to distribute workload and
+facilitate high throughputs. When storage nodes fail, data is
+re-replicated in a distributed fashion by the storage nodes themselves
+(with some minimal coordination from a cluster monitor), making the
+system extremely efficient and scalable.
+
+Metadata servers effectively form a large, consistent, distributed
+in-memory cache above the file namespace that is extremely scalable,
+dynamically redistributes metadata in response to workload changes,
+and can tolerate arbitrary (well, non-Byzantine) node failures. The
+metadata server takes a somewhat unconventional approach to metadata
+storage to significantly improve performance for common workloads. In
+particular, inodes with only a single link are embedded in
+directories, allowing entire directories of dentries and inodes to be
+loaded into its cache with a single I/O operation. The contents of
+extremely large directories can be fragmented and managed by
+independent metadata servers, allowing scalable concurrent access.
+
+The system offers automatic data rebalancing/migration when scaling
+from a small cluster of just a few nodes to many hundreds, without
+requiring an administrator carve the data set into static volumes or
+go through the tedious process of migrating data between servers.
+When the file system approaches full, new nodes can be easily added
+and things will "just work."
+
+Ceph includes flexible snapshot mechanism that allows a user to create
+a snapshot on any subdirectory (and its nested contents) in the
+system. Snapshot creation and deletion are as simple as 'mkdir
+.snap/foo' and 'rmdir .snap/foo'.
+
+Ceph also provides some recursive accounting on directories for nested
+files and bytes. That is, a 'getfattr -d foo' on any directory in the
+system will reveal the total number of nested regular files and
+subdirectories, and a summation of all nested file sizes. This makes
+the identification of large disk space consumers relatively quick, as
+no 'du' or similar recursive scan of the file system is required.
+
+
+Mount Syntax
+============
+
+The basic mount syntax is:
+
+ # mount -t ceph monip[:port][,monip2[:port]...]:/[subdir] mnt
+
+You only need to specify a single monitor, as the client will get the
+full list when it connects. (However, if the monitor you specify
+happens to be down, the mount won't succeed.) The port can be left
+off if the monitor is using the default. So if the monitor is at
+1.2.3.4,
+
+ # mount -t ceph 1.2.3.4:/ /mnt/ceph
+
+is sufficient. If /sbin/mount.ceph is installed, a hostname can be
+used instead of an IP address.
+
+
+
+Mount Options
+=============
+
+ ip=A.B.C.D[:N]
+ Specify the IP and/or port the client should bind to locally.
+ There is normally not much reason to do this. If the IP is not
+ specified, the client's IP address is determined by looking at the
+ address it's connection to the monitor originates from.
+
+ wsize=X
+ Specify the maximum write size in bytes. By default there is no
+ maximum. Ceph will normally size writes based on the file stripe
+ size.
+
+ rsize=X
+ Specify the maximum readahead.
+
+ mount_timeout=X
+ Specify the timeout value for mount (in seconds), in the case
+ of a non-responsive Ceph file system. The default is 30
+ seconds.
+
+ rbytes
+ When stat() is called on a directory, set st_size to 'rbytes',
+ the summation of file sizes over all files nested beneath that
+ directory. This is the default.
+
+ norbytes
+ When stat() is called on a directory, set st_size to the
+ number of entries in that directory.
+
+ nocrc
+ Disable CRC32C calculation for data writes. If set, the storage node
+ must rely on TCP's error correction to detect data corruption
+ in the data payload.
+
+ noasyncreaddir
+ Disable client's use its local cache to satisfy readdir
+ requests. (This does not change correctness; the client uses
+ cached metadata only when a lease or capability ensures it is
+ valid.)
+
+
+More Information
+================
+
+For more information on Ceph, see the home page at
+ http://ceph.newdream.net/
+
+The Linux kernel client source tree is available at
+ git://ceph.newdream.net/git/ceph-client.git
+ git://git.kernel.org/pub/scm/linux/kernel/git/sage/ceph-client.git
+
+and the source for the full system is at
+ git://ceph.newdream.net/git/ceph.git
diff --git a/Documentation/filesystems/tmpfs.txt b/Documentation/filesystems/tmpfs.txt
index 3015da0c6b2..fe09a2cb185 100644
--- a/Documentation/filesystems/tmpfs.txt
+++ b/Documentation/