REQ_META set during meta data write

Today, storage devices like eMMC has special features like data tagging
(introduced in MMC-4.5 version) in order to improve performance of some
specific writes. On MMC stack, data tagging is used for all writes which has
REQ_META flag set. On EXT4, however, currently REQ_META is set only for read.
This patch adds the capability to add REQ_META flag during meta data write.
This patch adds new function set_buffer_meta, which is used to set a bit
BH_Meta in the b_state field when meta data and super block is made dirty.

Signed-off-by: Saugata Das <saugata.das@linaro.org>
Acked-by: Arnd Bergmann <arnd.bergmann@linaro.org>

Changelog v2:
	- Removed check for WRITE when setting REQ_META in submit_bh
Changelog v1:
	- Introduction of REQ_META during write

Conflicts:
	arch/arm/boot/zImage
 OMAP4: NAND: Fix occasional errors and improve performance

The NAND command functions were not waiting for the attached chip to
indicate ready for some functions that they should have.  The changes
here reflect the use of the ready line by the Micron MT29F NAND Flash
Memory datasheet.

The routine omap_dev_ready() used the WAIT0EDGEDETECTION bit in the
GPMC_IRQSTATUS register.  This bit changes well after the NAND chip
raises the GPMC_WAIT0 input to indicate that it is ready.  The result
is that NAND reads and writes are quite slow.  It takes longer for
WAIT0EDGEDETECTION to reflect the proper status than it does to read
a page of data out of the NAND chip following the read command.  The
driver now uses WAIT0STATUS in the GPMC_STATUS register as per the TRM.

Signed-off-by: Steve Schefter <steve@scheftech.com>
OMAP: NAND BCH: Add eccsize and eccbytes to bcn struct

In the BCH4/8 support for OMAP2 is done only partly in hardware.
The error correction itself is done in software.
To use the lib/bch for error correction some changes have to be in the nand_bch.
The omap uses for bch8 eccsize=2048 and eccbytes=52 but does the
actual check and correction in four sub blocks. So we use in the nand_bch
code the eccsize=512 and eccbytes=13.
The used eccsize/eccbytes have to be saved in the bcn struct.

Signed-off-by: Steve Schefter <steve@scheftech.com>
OMAP4: NAND: use dev ready

Enable the use of the dev ready (GPMC_WAIT0) signal from the NAND
chip.  This increases the performance of NAND access.

This commit also modifies omap_write_buf_pref() to improve
performance and fixes DMA support for NAND.  The latter is not
turned on as it has a negative impact on NAND speed.

Signed-off-by: Steve Schefter <steve@scheftech.com>

Conflicts:
	drivers/mtd/nand/omap2.c

Conflicts:
	arch/arm/boot/zImage
 NAND: timing requirements not met

After the driver issues the commands NAND_CMD_SEQIN and
NAND_CMD_STATUS the chip does not assert the wait line, but it is
not immediately ready.  The driver must wait tADL and tWHR
respectively.

Signed-off-by: Steve Schefter <steve@scheftech.com>
OMAP4: NAND: fix for read error

Because the NAND interface uses the OMAP's general purpose memory
controller, part of the interface is implemented in software.
Specifically, the NAND driver monitors the ready line from the NAND
chip.  This is done using the WAIT0STATUS bit in the GPMC_STATUS
register.  It has been found that this can, on rare occasions for
at the start of a page read, indicate ready when the device is not
really ready to present the data.  Two positive reads produce
reliable results.  See details in omap_dev_ready().

While investigating this change, it was noted that the timing
specs for the NAND chip require a delay of tRR after the chip
indicates ready before it is actually ready to provide the data.
This was implenented in nand_command() and nand_command_lp(),
although no problem was observed without this delay.

Testing indicates that these changes have little or no effect
on the NAND read and write speeds.

Signed-off-by: Steve Schefter <steve@scheftech.com>
 ARM: OMAP2+: PRCM: Clear reset sources after boot

According to TRMs the reset source flags have to be cleared by
software, in another case the flags stay after reboot. So clear
them to avoid the flag gathering.

Change-Id: Ia4a5dadd67a2459f6b644d629768d7d51a365efb
Signed-off-by: Ivan Khoronzhuk <ivan.khoronzhuk@ti.com
ext4: remove unused ac_ex_scanned

When looking at a bug report with:

> kernel: EXT4-fs: 0 scanned, 0 found

I thought wow, 0 scanned, that's odd?  But it's not odd; it's printing
a variable that is initialized to 0 and never touched again.

It's never been used since the original merge, so I don't really even
know what the original intent was, either.

If anyone knows how to hook it up, speak now via patch, otherwise just
yank it so it's not making a confusing situation more confusing in
kernel logs.

Signed-off-by: Eric Sandeen <sandeen@redhat.com>
Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>

Conflicts:
	fs/ext4/mballoc.c

Conflicts:
	arch/arm/boot/zImage
ext4: don't calculate total xattr header size unless needed

The function ext4_expand_extra_isize_ea() doesn't need the size of all
of the extended attribute headers.  So if we don't calculate it when
it is unneeded, it we can skip some undeeded memory references, and as
a bonus, we eliminate some kvetching by static code analysis tools.

Addresses-Coverity-Id: #741291

Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>
ext4: address a benign compiler warning

When !defined(CONFIG_EXT4_DEBUG), mb_debug() should be defined as a
no_printk() statement instead of an empty statement in order to suppress
the following compiler warning:

fs/ext4/mballoc.c: In function ‘ext4_mb_cleanup_pa’:
fs/ext4/mballoc.c:2659:47: warning: suggest braces around empty body in an ‘if’ statement [-Wempty-body]
   mb_debug(1, "mballoc: %u PAs left\n", count);

Signed-off-by: Patrick Palka <patrick@parcs.ath.cx>
Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>
ext4: remove unreachable code in ext4_can_extents_be_merged()

Commit ec22ba8e ("ext4: disable merging of uninitialized extents")
ensured that if either extent under consideration is uninit, we
decline to merge, and immediately return.

But right after that test, we test again for an uninit
extent; we can never hit this.  So just remove the impossible
test and associated variable.

Signed-off-by: Eric Sandeen <sandeen@redhat.com>
Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>
Reviewed-by: Zheng Liu <wenqing.lz@taobao.com>
ext4: remove unreachable code after ext4_can_extents_be_merged()

Commit ec22ba8e ("ext4: disable merging of uninitialized extents")
ensured that if either extent under consideration is uninit, we
decline to merge, and ext4_can_extents_be_merged() returns false.

So there is no need for the caller to then test whether the
extent under consideration is unitialized; if it were, we
wouldn't have gotten that far.

The comments were also inaccurate; ext4_can_extents_be_merged()
no longer XORs the states, it fails if *either* is uninit.

Signed-off-by: Eric Sandeen <sandeen@redhat.com>
Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>
Reviewed-by: Zheng Liu <wenqing.lz@taobao.com>
Signed-off-by: Chet Kener <Cl3Kener@gmail.com>

Conflicts:
	fs/ext4/extents.c