Merge git://git.kernel.org/pub/scm/linux/kernel/git/davem/net

Conflicts:
	drivers/net/phy/marvell.c

Simple overlapping changes in drivers/net/phy/marvell.c

Signed-off-by: David S. Miller <davem@davemloft.net>

35 files changed, 934 insertions, 32 deletions

diff --git a/Documentation/ABI/testing/sysfs-ibft b/Documentation/ABI/testing/sysfs-ibft
index c2b7d1154bec..cac3930bdb04 100644
--- a/Documentation/ABI/testing/sysfs-ibft
+++ b/Documentation/ABI/testing/sysfs-ibft
@@ -20,4 +20,4 @@ Date:		November 2007
 Contact:	Konrad Rzeszutek <ketuzsezr@darnok.org>
 Description:	The /sys/firmware/ibft/ethernetX directory will contain
 		files that expose the iSCSI Boot Firmware Table NIC data.
-		This can this can the IP address, MAC, and gateway of the NIC.
+		Usually this contains the IP address, MAC, and gateway of the NIC.
diff --git a/Documentation/DocBook/media/Makefile b/Documentation/DocBook/media/Makefile
index df2962d9e11e..8bf7c6191296 100644
--- a/Documentation/DocBook/media/Makefile
+++ b/Documentation/DocBook/media/Makefile
@@ -25,7 +25,7 @@ GENFILES := $(addprefix $(MEDIA_OBJ_DIR)/, $(MEDIA_TEMP))
 PHONY += cleanmediadocs
 
 cleanmediadocs:
-	-@rm `find $(MEDIA_OBJ_DIR) -type l` $(GENFILES) $(OBJIMGFILES) 2>/dev/null
+	-@rm -f `find $(MEDIA_OBJ_DIR) -type l` $(GENFILES) $(OBJIMGFILES) 2>/dev/null
 
 $(obj)/media_api.xml: $(GENFILES) FORCE
 
diff --git a/Documentation/DocBook/media/v4l/compat.xml b/Documentation/DocBook/media/v4l/compat.xml
index 07ffc76553ba..0a2debfa68f6 100644
--- a/Documentation/DocBook/media/v4l/compat.xml
+++ b/Documentation/DocBook/media/v4l/compat.xml
@@ -2566,6 +2566,10 @@ fields changed from _s32 to _u32.
 	  <para>Added compound control types and &VIDIOC-QUERY-EXT-CTRL;.
 	  </para>
         </listitem>
+      </orderedlist>
+    </section>
+
+    <section>
       <title>V4L2 in Linux 3.18</title>
       <orderedlist>
 	<listitem>
diff --git a/Documentation/HOWTO b/Documentation/HOWTO
index 57cf5efb044d..93aa8604630e 100644
--- a/Documentation/HOWTO
+++ b/Documentation/HOWTO
@@ -324,7 +324,6 @@ tree, they need to be integration-tested.  For this purpose, a special
 testing repository exists into which virtually all subsystem trees are
 pulled on an almost daily basis:
 	http://git.kernel.org/?p=linux/kernel/git/next/linux-next.git
-	http://linux.f-seidel.de/linux-next/pmwiki/
 
 This way, the -next kernel gives a summary outlook onto what will be
 expected to go into the mainline kernel at the next merge period.
diff --git a/Documentation/SubmittingPatches b/Documentation/SubmittingPatches
index 482c74947de0..1fa1caa198eb 100644
--- a/Documentation/SubmittingPatches
+++ b/Documentation/SubmittingPatches
@@ -483,12 +483,10 @@ have been included in the discussion
 
 14) Using Reported-by:, Tested-by:, Reviewed-by:, Suggested-by: and Fixes:
 
-If this patch fixes a problem reported by somebody else, consider adding a
-Reported-by: tag to credit the reporter for their contribution.  Please
-note that this tag should not be added without the reporter's permission,
-especially if the problem was not reported in a public forum.  That said,
-if we diligently credit our bug reporters, they will, hopefully, be
-inspired to help us again in the future.
+The Reported-by tag gives credit to people who find bugs and report them and it
+hopefully inspires them to help us again in the future.  Please note that if
+the bug was reported in private, then ask for permission first before using the
+Reported-by tag.
 
 A Tested-by: tag indicates that the patch has been successfully tested (in
 some environment) by the person named.  This tag informs maintainers that
diff --git a/Documentation/arm64/memory.txt b/Documentation/arm64/memory.txt
index 344e85cc7323..d7273a5f6456 100644
--- a/Documentation/arm64/memory.txt
+++ b/Documentation/arm64/memory.txt
@@ -17,7 +17,7 @@ User addresses have bits 63:48 set to 0 while the kernel addresses have
 the same bits set to 1. TTBRx selection is given by bit 63 of the
 virtual address. The swapper_pg_dir contains only kernel (global)
 mappings while the user pgd contains only user (non-global) mappings.
-The swapper_pgd_dir address is written to TTBR1 and never written to
+The swapper_pg_dir address is written to TTBR1 and never written to
 TTBR0.
 
 
diff --git a/Documentation/development-process/2.Process b/Documentation/development-process/2.Process
index 2e0617936e8f..c24e156a6118 100644
--- a/Documentation/development-process/2.Process
+++ b/Documentation/development-process/2.Process
@@ -289,10 +289,6 @@ lists when they are assembled; they can be downloaded from:
 
 	http://www.kernel.org/pub/linux/kernel/next/
 
-Some information about linux-next has been gathered at:
-
-	http://linux.f-seidel.de/linux-next/pmwiki/
-
 Linux-next has become an integral part of the kernel development process;
 all patches merged during a given merge window should really have found
 their way into linux-next some time before the merge window opens.
diff --git a/Documentation/development-process/8.Conclusion b/Documentation/development-process/8.Conclusion
index 1990ab4b4949..caef69022e9c 100644
--- a/Documentation/development-process/8.Conclusion
+++ b/Documentation/development-process/8.Conclusion
@@ -22,10 +22,6 @@ Beyond that, a valuable resource for kernel developers is:
 
 	http://kernelnewbies.org/
 
-Information about the linux-next tree gathers at:
-
-	http://linux.f-seidel.de/linux-next/pmwiki/
-
 And, of course, one should not forget http://kernel.org/, the definitive
 location for kernel release information.
 
diff --git a/Documentation/devicetree/bindings/mailbox/mailbox.txt b/Documentation/devicetree/bindings/mailbox/mailbox.txt
new file mode 100644
index 000000000000..1a2cd3d266db
--- /dev/null
+++ b/Documentation/devicetree/bindings/mailbox/mailbox.txt
@@ -0,0 +1,38 @@
+* Generic Mailbox Controller and client driver bindings
+
+Generic binding to provide a way for Mailbox controller drivers to
+assign appropriate mailbox channel to client drivers.
+
+* Mailbox Controller
+
+Required property:
+- #mbox-cells: Must be at least 1. Number of cells in a mailbox
+		specifier.
+
+Example:
+	mailbox: mailbox {
+		...
+		#mbox-cells = <1>;
+	};
+
+
+* Mailbox Client
+
+Required property:
+- mboxes: List of phandle and mailbox channel specifiers.
+
+Optional property:
+- mbox-names: List of identifier strings for each mailbox channel
+		required by the client. The use of this property
+		is discouraged in favor of using index in list of
+		'mboxes' while requesting a mailbox. Instead the
+		platforms may define channel indices, in DT headers,
+		to something legible.
+
+Example:
+	pwr_cntrl: power {
+		...
+		mbox-names = "pwr-ctrl", "rpc";
+		mboxes = <&mailbox 0
+			&mailbox 1>;
+	};
diff --git a/Documentation/devicetree/bindings/net/smsc-lan91c111.txt b/Documentation/devicetree/bindings/net/smsc-lan91c111.txt
index 0f8487b88822..e77e167593db 100644
--- a/Documentation/devicetree/bindings/net/smsc-lan91c111.txt
+++ b/Documentation/devicetree/bindings/net/smsc-lan91c111.txt
@@ -11,3 +11,5 @@ Optional properties:
   are supported on the device.  Valid value for SMSC LAN91c111 are
   1, 2 or 4.  If it's omitted or invalid, the size would be 2 meaning
   16-bit access only.
+- power-gpios: GPIO to control the PWRDWN pin
+- reset-gpios: GPIO to control the RESET pin
diff --git a/Documentation/devicetree/bindings/pwm/pwm-fsl-ftm.txt b/Documentation/devicetree/bindings/pwm/pwm-fsl-ftm.txt
index 0bda229a6171..3899d6a557c1 100644
--- a/Documentation/devicetree/bindings/pwm/pwm-fsl-ftm.txt
+++ b/Documentation/devicetree/bindings/pwm/pwm-fsl-ftm.txt
@@ -1,5 +1,20 @@
 Freescale FlexTimer Module (FTM) PWM controller
 
+The same FTM PWM device can have a different endianness on different SoCs. The
+device tree provides a property to describing this so that an operating system
+device driver can handle all variants of the device. Refer to the table below
+for the endianness of the FTM PWM block as integrated into the existing SoCs:
+
+	SoC     | FTM-PWM endianness
+	--------+-------------------
+	Vybrid  | LE
+	LS1     | BE
+	LS2     | LE
+
+Please see ../regmap/regmap.txt for more detail about how to specify endian
+modes in device tree.
+
+
 Required properties:
 - compatible: Should be "fsl,vf610-ftm-pwm".
 - reg: Physical base address and length of the controller's registers
@@ -16,7 +31,8 @@ Required properties:
 - pinctrl-names: Must contain a "default" entry.
 - pinctrl-NNN: One property must exist for each entry in pinctrl-names.
   See pinctrl/pinctrl-bindings.txt for details of the property values.
-
+- big-endian: Boolean property, required if the FTM PWM registers use a big-
+  endian rather than little-endian layout.
 
 Example:
 
@@ -32,4 +48,5 @@ pwm0: pwm@40038000 {
 			<&clks VF610_CLK_FTM0_EXT_FIX_EN>;
 		pinctrl-names = "default";
 		pinctrl-0 = <&pinctrl_pwm0_1>;
+		big-endian;
 };
diff --git a/Documentation/devicetree/bindings/pwm/pwm-rockchip.txt b/Documentation/devicetree/bindings/pwm/pwm-rockchip.txt
index d47d15a6a298..b8be3d09ee26 100644
--- a/Documentation/devicetree/bindings/pwm/pwm-rockchip.txt
+++ b/Documentation/devicetree/bindings/pwm/pwm-rockchip.txt
@@ -7,8 +7,8 @@ Required properties:
    "rockchip,vop-pwm": found integrated in VOP on RK3288 SoC
  - reg: physical base address and length of the controller's registers
  - clocks: phandle and clock specifier of the PWM reference clock
- - #pwm-cells: should be 2. See pwm.txt in this directory for a
-   description of the cell format.
+ - #pwm-cells: must be 2 (rk2928) or 3 (rk3288). See pwm.txt in this directory
+   for a description of the cell format.
 
 Example:
 
diff --git a/Documentation/devicetree/bindings/sound/sgtl5000.txt b/Documentation/devicetree/bindings/sound/sgtl5000.txt
index 955df60a118c..d556dcb8816b 100644
--- a/Documentation/devicetree/bindings/sound/sgtl5000.txt
+++ b/Documentation/devicetree/bindings/sound/sgtl5000.txt
@@ -7,10 +7,20 @@ Required properties:
 
 - clocks : the clock provider of SYS_MCLK
 
+- VDDA-supply : the regulator provider of VDDA
+
+- VDDIO-supply: the regulator provider of VDDIO
+
+Optional properties:
+
+- VDDD-supply : the regulator provider of VDDD
+
 Example:
 
 codec: sgtl5000@0a {
 	compatible = "fsl,sgtl5000";
 	reg = <0x0a>;
 	clocks = <&clks 150>;
+	VDDA-supply = <&reg_3p3v>;
+	VDDIO-supply = <&reg_3p3v>;
 };
diff --git a/Documentation/devicetree/bindings/submitting-patches.txt b/Documentation/devicetree/bindings/submitting-patches.txt
index 042a0273b8ba..b7ba01ad1426 100644
--- a/Documentation/devicetree/bindings/submitting-patches.txt
+++ b/Documentation/devicetree/bindings/submitting-patches.txt
@@ -12,6 +12,9 @@ I. For patch submitters
 
        devicetree@vger.kernel.org
 
+  3) The Documentation/ portion of the patch should come in the series before
+     the code implementing the binding.
+
 II. For kernel maintainers
 
   1) If you aren't comfortable reviewing a given binding, reply to it and ask
diff --git a/Documentation/devicetree/bindings/thermal/imx-thermal.txt b/Documentation/devicetree/bindings/thermal/imx-thermal.txt
index 1f0f67234a91..3c67bd50aa10 100644
--- a/Documentation/devicetree/bindings/thermal/imx-thermal.txt
+++ b/Documentation/devicetree/bindings/thermal/imx-thermal.txt
@@ -1,7 +1,10 @@
 * Temperature Monitor (TEMPMON) on Freescale i.MX SoCs
 
 Required properties:
-- compatible : "fsl,imx6q-thermal"
+- compatible : "fsl,imx6q-tempmon" for i.MX6Q, "fsl,imx6sx-tempmon" for i.MX6SX.
+  i.MX6SX has two more IRQs than i.MX6Q, one is IRQ_LOW and the other is IRQ_PANIC,
+  when temperature is below than low threshold, IRQ_LOW will be triggered, when temperature
+  is higher than panic threshold, system will auto reboot by SRC module.
 - fsl,tempmon : phandle pointer to system controller that contains TEMPMON
   control registers, e.g. ANATOP on imx6q.
 - fsl,tempmon-data : phandle pointer to fuse controller that contains TEMPMON
diff --git a/Documentation/devicetree/bindings/vendor-prefixes.txt b/Documentation/devicetree/bindings/vendor-prefixes.txt
index c7bb11be15a3..723999d73744 100644
--- a/Documentation/devicetree/bindings/vendor-prefixes.txt
+++ b/Documentation/devicetree/bindings/vendor-prefixes.txt
@@ -140,6 +140,7 @@ sitronix	Sitronix Technology Corporation
 smsc	Standard Microsystems Corporation
 snps 	Synopsys, Inc.
 solidrun	SolidRun
+sony	Sony Corporation
 spansion	Spansion Inc.
 st	STMicroelectronics
 ste	ST-Ericsson
diff --git a/Documentation/devicetree/bindings/watchdog/cadence-wdt.txt b/Documentation/devicetree/bindings/watchdog/cadence-wdt.txt
new file mode 100644
index 000000000000..c3a36ee45552
--- /dev/null
+++ b/Documentation/devicetree/bindings/watchdog/cadence-wdt.txt
@@ -0,0 +1,24 @@
+Zynq Watchdog Device Tree Bindings
+-------------------------------------------
+
+Required properties:
+- compatible		: Should be "cdns,wdt-r1p2".
+- clocks		: This is pclk (APB clock).
+- interrupts		: This is wd_irq - watchdog timeout interrupt.
+- interrupt-parent	: Must be core interrupt controller.
+
+Optional properties
+- reset-on-timeout	: If this property exists, then a reset is done
+			  when watchdog times out.
+- timeout-sec		: Watchdog timeout value (in seconds).
+
+Example:
+	watchdog@f8005000 {
+		compatible = "cdns,wdt-r1p2";
+		clocks = <&clkc 45>;
+		interrupt-parent = <&intc>;
+		interrupts = <0 9 1>;
+		reg = <0xf8005000 0x1000>;
+		reset-on-timeout;
+		timeout-sec = <10>;
+	};
diff --git a/Documentation/devicetree/bindings/watchdog/fsl-imx-wdt.txt b/Documentation/devicetree/bindings/watchdog/fsl-imx-wdt.txt
index e52ba2da868c..8dab6fd024aa 100644
--- a/Documentation/devicetree/bindings/watchdog/fsl-imx-wdt.txt
+++ b/Documentation/devicetree/bindings/watchdog/fsl-imx-wdt.txt
@@ -7,7 +7,8 @@ Required properties:
 
 Optional property:
 - big-endian: If present the watchdog device's registers are implemented
-  in big endian mode, otherwise in little mode.
+  in big endian mode, otherwise in native mode(same with CPU), for more
+  detail please see: Documentation/devicetree/bindings/regmap/regmap.txt.
 
 Examples:
 
diff --git a/Documentation/devicetree/bindings/watchdog/meson6-wdt.txt b/Documentation/devicetree/bindings/watchdog/meson6-wdt.txt
new file mode 100644
index 000000000000..9200fc2d508c
--- /dev/null
+++ b/Documentation/devicetree/bindings/watchdog/meson6-wdt.txt
@@ -0,0 +1,13 @@
+Meson SoCs Watchdog timer
+
+Required properties:
+
+- compatible : should be "amlogic,meson6-wdt"
+- reg : Specifies base physical address and size of the registers.
+
+Example:
+
+wdt: watchdog@c1109900 {
+	compatible = "amlogic,meson6-wdt";
+	reg = <0xc1109900 0x8>;
+};
diff --git a/Documentation/devicetree/bindings/watchdog/qcom-wdt.txt b/Documentation/devicetree/bindings/watchdog/qcom-wdt.txt
new file mode 100644
index 000000000000..4726924d034e
--- /dev/null
+++ b/Documentation/devicetree/bindings/watchdog/qcom-wdt.txt
@@ -0,0 +1,24 @@
+Qualcomm Krait Processor Sub-system (KPSS) Watchdog
+---------------------------------------------------
+
+Required properties :
+- compatible : shall contain only one of the following:
+
+			"qcom,kpss-wdt-msm8960"
+			"qcom,kpss-wdt-apq8064"
+			"qcom,kpss-wdt-ipq8064"
+
+- reg : shall contain base register location and length
+- clocks : shall contain the input clock
+
+Optional properties :
+- timeout-sec : shall contain the default watchdog timeout in seconds,
+                if unset, the default timeout is 30 seconds
+
+Example:
+	watchdog@208a038 {
+		compatible = "qcom,kpss-wdt-ipq8064";
+		reg = <0x0208a038 0x40>;
+		clocks = <&sleep_clk>;
+		timeout-sec = <10>;
+	};
diff --git a/Documentation/devicetree/bindings/watchdog/samsung-wdt.txt b/Documentation/devicetree/bindings/watchdog/samsung-wdt.txt
index cfff37511aac..8f3d96af81d7 100644
--- a/Documentation/devicetree/bindings/watchdog/samsung-wdt.txt
+++ b/Documentation/devicetree/bindings/watchdog/samsung-wdt.txt
@@ -9,6 +9,7 @@ Required properties:
 	(a) "samsung,s3c2410-wdt" for Exynos4 and previous SoCs
 	(b) "samsung,exynos5250-wdt" for Exynos5250
 	(c) "samsung,exynos5420-wdt" for Exynos5420
+	(c) "samsung,exynos7-wdt" for Exynos7
 
 - reg : base physical address of the controller and length of memory mapped
 	region.
diff --git a/Documentation/filesystems/Locking b/Documentation/filesystems/Locking
index 94d93b1f8b53..b30753cbf431 100644
--- a/Documentation/filesystems/Locking
+++ b/Documentation/filesystems/Locking
@@ -67,6 +67,7 @@ prototypes:
 				struct file *, unsigned open_flag,
 				umode_t create_mode, int *opened);
 	int (*tmpfile) (struct inode *, struct dentry *, umode_t);
+	int (*dentry_open)(struct dentry *, struct file *, const struct cred *);
 
 locking rules:
 	all may block
@@ -96,6 +97,7 @@ fiemap:		no
 update_time:	no
 atomic_open:	yes
 tmpfile:	no
+dentry_open:	no
 
 	Additionally, ->rmdir(), ->unlink() and ->rename() have ->i_mutex on
 victim.
diff --git a/Documentation/filesystems/overlayfs.txt b/Documentation/filesystems/overlayfs.txt
new file mode 100644
index 000000000000..530850a72735
--- /dev/null
+++ b/Documentation/filesystems/overlayfs.txt
@@ -0,0 +1,198 @@
+Written by: Neil Brown <neilb@suse.de>
+
+Overlay Filesystem
+==================
+
+This document describes a prototype for a new approach to providing
+overlay-filesystem functionality in Linux (sometimes referred to as
+union-filesystems).  An overlay-filesystem tries to present a
+filesystem which is the result over overlaying one filesystem on top
+of the other.
+
+The result will inevitably fail to look exactly like a normal
+filesystem for various technical reasons.  The expectation is that
+many use cases will be able to ignore these differences.
+
+This approach is 'hybrid' because the objects that appear in the
+filesystem do not all appear to belong to that filesystem.  In many
+cases an object accessed in the union will be indistinguishable
+from accessing the corresponding object from the original filesystem.
+This is most obvious from the 'st_dev' field returned by stat(2).
+
+While directories will report an st_dev from the overlay-filesystem,
+all non-directory objects will report an st_dev from the lower or
+upper filesystem that is providing the object.  Similarly st_ino will
+only be unique when combined with st_dev, and both of these can change
+over the lifetime of a non-directory object.  Many applications and
+tools ignore these values and will not be affected.
+
+Upper and Lower
+---------------
+
+An overlay filesystem combines two filesystems - an 'upper' filesystem
+and a 'lower' filesystem.  When a name exists in both filesystems, the
+object in the 'upper' filesystem is visible while the object in the
+'lower' filesystem is either hidden or, in the case of directories,
+merged with the 'upper' object.
+
+It would be more correct to refer to an upper and lower 'directory
+tree' rather than 'filesystem' as it is quite possible for both
+directory trees to be in the same filesystem and there is no
+requirement that the root of a filesystem be given for either upper or
+lower.
+
+The lower filesystem can be any filesystem supported by Linux and does
+not need to be writable.  The lower filesystem can even be another
+overlayfs.  The upper filesystem will normally be writable and if it
+is it must support the creation of trusted.* extended attributes, and
+must provide valid d_type in readdir responses, so NFS is not suitable.
+
+A read-only overlay of two read-only filesystems may use any
+filesystem type.
+
+Directories
+-----------
+
+Overlaying mainly involves directories.  If a given name appears in both
+upper and lower filesystems and refers to a non-directory in either,
+then the lower object is hidden - the name refers only to the upper
+object.
+
+Where both upper and lower objects are directories, a merged directory
+is formed.
+
+At mount time, the two directories given as mount options "lowerdir" and
+"upperdir" are combined into a merged directory:
+
+  mount -t overlayfs overlayfs -olowerdir=/lower,upperdir=/upper,\
+workdir=/work /merged
+
+The "workdir" needs to be an empty directory on the same filesystem
+as upperdir.
+
+Then whenever a lookup is requested in such a merged directory, the
+lookup is performed in each actual directory and the combined result
+is cached in the dentry belonging to the overlay filesystem.  If both
+actual lookups find directories, both are stored and a merged
+directory is created, otherwise only one is stored: the upper if it
+exists, else the lower.
+
+Only the lists of names from directories are merged.  Other content
+such as metadata and extended attributes are reported for the upper
+directory only.  These attributes of the lower directory are hidden.
+
+whiteouts and opaque directories
+--------------------------------
+
+In order to support rm and rmdir without changing the lower
+filesystem, an overlay filesystem needs to record in the upper filesystem
+that files have been removed.  This is done using whiteouts and opaque
+directories (non-directories are always opaque).
+
+A whiteout is created as a character device with 0/0 device number.
+When a whiteout is found in the upper level of a merged directory, any
+matching name in the lower level is ignored, and the whiteout itself
+is also hidden.
+
+A directory is made opaque by setting the xattr "trusted.overlay.opaque"
+to "y".  Where the upper filesystem contains an opaque directory, any
+directory in the lower filesystem with the same name is ignored.
+
+readdir
+-------
+
+When a 'readdir' request is made on a merged directory, the upper and
+lower directories are each read and the name lists merged in the
+obvious way (upper is read first, then lower - entries that already
+exist are not re-added).  This merged name list is cached in the
+'struct file' and so remains as long as the file is kept open.  If the
+directory is opened and read by two processes at the same time, they
+will each have separate caches.  A seekdir to the start of the
+directory (offset 0) followed by a readdir will cause the cache to be
+discarded and rebuilt.
+
+This means that changes to the merged directory do not appear while a
+directory is being read.  This is unlikely to be noticed by many
+programs.
+
+seek offsets are assigned sequentially when the directories are read.
+Thus if
+  - read part of a directory
+  - remember an offset, and close the directory
+  - re-open the directory some time later
+  - seek to the remembered offset
+
+there may be little correlation between the old and new locations in
+the list of filenames, particularly if anything has changed in the
+directory.
+
+Readdir on directories that are not merged is simply handled by the
+underlying directory (upper or lower).
+
+
+Non-directories
+---------------
+
+Objects that are not directories (files, symlinks, device-special
+files etc.) are presented either from the upper or lower filesystem as
+appropriate.  When a file in the lower filesystem is accessed in a way
+the requires write-access, such as opening for write access, changing
+some metadata etc., the file is first copied from the lower filesystem
+to the upper filesystem (copy_up).  Note that creating a hard-link
+also requires copy_up, though of course creation of a symlink does
+not.
+
+The copy_up may turn out to be unnecessary, for example if the file is
+opened for read-write but the data is not modified.
+
+The copy_up process first makes sure that the containing directory
+exists in the upper filesystem - creating it and any parents as
+necessary.  It then creates the object with the same metadata (owner,
+mode, mtime, symlink-target etc.) and then if the object is a file, the
+data is copied from the lower to the upper filesystem.  Finally any
+extended attributes are copied up.
+
+Once the copy_up is complete, the overlay filesystem simply
+provides direct access to the newly created file in the upper
+filesystem - future operations on the file are barely noticed by the
+overlay filesystem (though an operation on the name of the file such as
+rename or unlink will of course be noticed and handled).
+
+
+Non-standard behavior
+---------------------
+
+The copy_up operation essentially creates a new, identical file and
+moves it over to the old name.  The new file may be on a different
+filesystem, so both st_dev and st_ino of the file may change.
+
+Any open files referring to this inode will access the old data and
+metadata.  Similarly any file locks obtained before copy_up will not
+apply to the copied up file.
+
+On a file opened with O_RDONLY fchmod(2), fchown(2), futimesat(2) and
+fsetxattr(2) will fail with EROFS.
+
+If a file with multiple hard links is copied up, then this will
+"break" the link.  Changes will not be propagated to other names
+referring to the same inode.
+
+Symlinks in /proc/PID/ and /proc/PID/fd which point to a non-directory
+object in overlayfs will not contain valid absolute paths, only
+relative paths leading up to the filesystem's root.  This will be
+fixed in the future.
+
+Some operations are not atomic, for example a crash during copy_up or
+rename will leave the filesystem in an inconsistent state.  This will
+be addressed in the future.
+
+Changes to underlying filesystems
+---------------------------------
+
+Offline changes, when the overlay is not mounted, are allowed to either
+the upper or the lower trees.
+
+Changes to the underlying filesystems while part of a mounted overlay
+filesystem are not allowed.  If the underlying filesystem is changed,
+the behavior of the overlay is undefined, though it will not result in
+a crash or deadlock.
diff --git a/Documentation/filesystems/vfs.txt b/Documentation/filesystems/vfs.txt
index fceff7c00a3c..20bf204426ca 100644
--- a/Documentation/filesystems/vfs.txt
+++ b/Documentation/filesystems/vfs.txt
@@ -364,6 +364,7 @@ struct inode_operations {
 	int (*atomic_open)(struct inode *, struct dentry *, struct file *,
 			unsigned open_flag, umode_t create_mode, int *opened);
 	int (*tmpfile) (struct inode *, struct dentry *, umode_t);
+	int (*dentry_open)(struct dentry *, struct file *, const struct cred *);
 };
 
 Again, all methods are called without any locks being held, unless