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r: 375029
b: refs/heads/master
c: fc72053
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  375027: 81fa5e0
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Linus Torvalds committed May 9, 2013
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2 changes: 1 addition & 1 deletion [refs]
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---
refs/heads/master: c58c1a4c118ba2ed49f72de9b42ef13bc8ee71e5
refs/heads/master: fc72053bb497e3054d6e4d13ab425fc2311442d4
180 changes: 173 additions & 7 deletions trunk/Documentation/filesystems/btrfs.txt
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@@ -1,8 +1,8 @@

BTRFS
=====
BTRFS
=====

Btrfs is a new copy on write filesystem for Linux aimed at
Btrfs is a copy on write filesystem for Linux aimed at
implementing advanced features while focusing on fault tolerance,
repair and easy administration. Initially developed by Oracle, Btrfs
is licensed under the GPL and open for contribution from anyone.
Expand Down Expand Up @@ -34,9 +34,175 @@ The main Btrfs features include:
* Online filesystem defragmentation


Mount Options
=============

MAILING LIST
============
When mounting a btrfs filesystem, the following option are accepted.
Unless otherwise specified, all options default to off.

alloc_start=<bytes>
Debugging option to force all block allocations above a certain
byte threshold on each block device. The value is specified in
bytes, optionally with a K, M, or G suffix, case insensitive.
Default is 1MB.

autodefrag
Detect small random writes into files and queue them up for the
defrag process. Works best for small files; Not well suited for
large database workloads.

check_int
check_int_data
check_int_print_mask=<value>
These debugging options control the behavior of the integrity checking
module (the BTRFS_FS_CHECK_INTEGRITY config option required).

check_int enables the integrity checker module, which examines all
block write requests to ensure on-disk consistency, at a large
memory and CPU cost.

check_int_data includes extent data in the integrity checks, and
implies the check_int option.

check_int_print_mask takes a bitmask of BTRFSIC_PRINT_MASK_* values
as defined in fs/btrfs/check-integrity.c, to control the integrity
checker module behavior.

See comments at the top of fs/btrfs/check-integrity.c for more info.

compress
compress=<type>
compress-force
compress-force=<type>
Control BTRFS file data compression. Type may be specified as "zlib"
"lzo" or "no" (for no compression, used for remounting). If no type
is specified, zlib is used. If compress-force is specified,
all files will be compressed, whether or not they compress well.
If compression is enabled, nodatacow and nodatasum are disabled.

degraded
Allow mounts to continue with missing devices. A read-write mount may
fail with too many devices missing, for example if a stripe member
is completely missing.

device=<devicepath>
Specify a device during mount so that ioctls on the control device
can be avoided. Especialy useful when trying to mount a multi-device
setup as root. May be specified multiple times for multiple devices.

discard
Issue frequent commands to let the block device reclaim space freed by
the filesystem. This is useful for SSD devices, thinly provisioned
LUNs and virtual machine images, but may have a significant
performance impact. (The fstrim command is also available to
initiate batch trims from userspace).

enospc_debug
Debugging option to be more verbose in some ENOSPC conditions.

fatal_errors=<action>
Action to take when encountering a fatal error:
"bug" - BUG() on a fatal error. This is the default.
"panic" - panic() on a fatal error.

flushoncommit
The 'flushoncommit' mount option forces any data dirtied by a write in a
prior transaction to commit as part of the current commit. This makes
the committed state a fully consistent view of the file system from the
application's perspective (i.e., it includes all completed file system
operations). This was previously the behavior only when a snapshot is
created.

inode_cache
Enable free inode number caching. Defaults to off due to an overflow
problem when the free space crcs don't fit inside a single page.

max_inline=<bytes>
Specify the maximum amount of space, in bytes, that can be inlined in
a metadata B-tree leaf. The value is specified in bytes, optionally
with a K, M, or G suffix, case insensitive. In practice, this value
is limited by the root sector size, with some space unavailable due
to leaf headers. For a 4k sectorsize, max inline data is ~3900 bytes.

metadata_ratio=<value>
Specify that 1 metadata chunk should be allocated after every <value>
data chunks. Off by default.

noacl
Disable support for Posix Access Control Lists (ACLs). See the
acl(5) manual page for more information about ACLs.

nobarrier
Disables the use of block layer write barriers. Write barriers ensure
that certain IOs make it through the device cache and are on persistent
storage. If used on a device with a volatile (non-battery-backed)
write-back cache, this option will lead to filesystem corruption on a
system crash or power loss.

nodatacow
Disable data copy-on-write for newly created files. Implies nodatasum,
and disables all compression.

nodatasum
Disable data checksumming for newly created files.

notreelog
Disable the tree logging used for fsync and O_SYNC writes.

recovery
Enable autorecovery attempts if a bad tree root is found at mount time.
Currently this scans a list of several previous tree roots and tries to
use the first readable.

skip_balance
Skip automatic resume of interrupted balance operation after mount.
May be resumed with "btrfs balance resume."

space_cache (*)
Enable the on-disk freespace cache.
nospace_cache
Disable freespace cache loading without clearing the cache.
clear_cache
Force clearing and rebuilding of the disk space cache if something
has gone wrong.

ssd
nossd
ssd_spread
Options to control ssd allocation schemes. By default, BTRFS will
enable or disable ssd allocation heuristics depending on whether a
rotational or nonrotational disk is in use. The ssd and nossd options
can override this autodetection.

The ssd_spread mount option attempts to allocate into big chunks
of unused space, and may perform better on low-end ssds. ssd_spread
implies ssd, enabling all other ssd heuristics as well.

subvol=<path>
Mount subvolume at <path> rather than the root subvolume. <path> is
relative to the top level subvolume.

subvolid=<ID>
Mount subvolume specified by an ID number rather than the root subvolume.
This allows mounting of subvolumes which are not in the root of the mounted
filesystem.
You can use "btrfs subvolume list" to see subvolume ID numbers.

subvolrootid=<objectid> (deprecated)
Mount subvolume specified by <objectid> rather than the root subvolume.
This allows mounting of subvolumes which are not in the root of the mounted
filesystem.
You can use "btrfs subvolume show " to see the object ID for a subvolume.

thread_pool=<number>
The number of worker threads to allocate. The default number is equal
to the number of CPUs + 2, or 8, whichever is smaller.

user_subvol_rm_allowed
Allow subvolumes to be deleted by a non-root user. Use with caution.

MAILING LIST
============

There is a Btrfs mailing list hosted on vger.kernel.org. You can
find details on how to subscribe here:
Expand All @@ -49,8 +215,8 @@ http://dir.gmane.org/gmane.comp.file-systems.btrfs



IRC
===
IRC
===

Discussion of Btrfs also occurs on the #btrfs channel of the Freenode
IRC network.
Expand Down
46 changes: 46 additions & 0 deletions trunk/Documentation/xtensa/mmu.txt
Original file line number Diff line number Diff line change
@@ -0,0 +1,46 @@
MMUv3 initialization sequence.

The code in the initialize_mmu macro sets up MMUv3 memory mapping
identically to MMUv2 fixed memory mapping. Depending on
CONFIG_INITIALIZE_XTENSA_MMU_INSIDE_VMLINUX symbol this code is
located in one of the following address ranges:

0xF0000000..0xFFFFFFFF (will keep same address in MMU v2 layout;
typically ROM)
0x00000000..0x07FFFFFF (system RAM; this code is actually linked
at 0xD0000000..0xD7FFFFFF [cached]
or 0xD8000000..0xDFFFFFFF [uncached];
in any case, initially runs elsewhere
than linked, so have to be careful)

The code has the following assumptions:
This code fragment is run only on an MMU v3.
TLBs are in their reset state.
ITLBCFG and DTLBCFG are zero (reset state).
RASID is 0x04030201 (reset state).
PS.RING is zero (reset state).
LITBASE is zero (reset state, PC-relative literals); required to be PIC.

TLB setup proceeds along the following steps.

Legend:
VA = virtual address (two upper nibbles of it);
PA = physical address (two upper nibbles of it);
pc = physical range that contains this code;

After step 2, we jump to virtual address in 0x40000000..0x5fffffff
that corresponds to next instruction to execute in this code.
After step 4, we jump to intended (linked) address of this code.

Step 0 Step1 Step 2 Step3 Step 4 Step5
============ ===== ============ ===== ============ =====
VA PA PA VA PA PA VA PA PA
------ -- -- ------ -- -- ------ -- --
E0..FF -> E0 -> E0 E0..FF -> E0 F0..FF -> F0 -> F0
C0..DF -> C0 -> C0 C0..DF -> C0 E0..EF -> F0 -> F0
A0..BF -> A0 -> A0 A0..BF -> A0 D8..DF -> 00 -> 00
80..9F -> 80 -> 80 80..9F -> 80 D0..D7 -> 00 -> 00
60..7F -> 60 -> 60 60..7F -> 60
40..5F -> 40 40..5F -> pc -> pc 40..5F -> pc
20..3F -> 20 -> 20 20..3F -> 20
00..1F -> 00 -> 00 00..1F -> 00
31 changes: 11 additions & 20 deletions trunk/arch/arc/Kconfig
Original file line number Diff line number Diff line change
Expand Up @@ -16,8 +16,6 @@ config ARC
select GENERIC_FIND_FIRST_BIT
# for now, we don't need GENERIC_IRQ_PROBE, CONFIG_GENERIC_IRQ_CHIP
select GENERIC_IRQ_SHOW
select GENERIC_KERNEL_EXECVE
select GENERIC_KERNEL_THREAD
select GENERIC_PENDING_IRQ if SMP
select GENERIC_SMP_IDLE_THREAD
select HAVE_ARCH_KGDB
Expand Down Expand Up @@ -61,9 +59,6 @@ config GENERIC_CALIBRATE_DELAY
config GENERIC_HWEIGHT
def_bool y

config BINFMT_ELF
def_bool y

config STACKTRACE_SUPPORT
def_bool y
select STACKTRACE
Expand All @@ -82,6 +77,7 @@ menu "ARC Architecture Configuration"
menu "ARC Platform/SoC/Board"

source "arch/arc/plat-arcfpga/Kconfig"
source "arch/arc/plat-tb10x/Kconfig"
#New platform adds here

endmenu
Expand Down Expand Up @@ -134,9 +130,6 @@ if SMP
config ARC_HAS_COH_CACHES
def_bool n

config ARC_HAS_COH_LLSC
def_bool n

config ARC_HAS_COH_RTSC
def_bool n

Expand Down Expand Up @@ -304,6 +297,9 @@ config ARC_FPU_SAVE_RESTORE
based on actual usage of FPU by a task. Thus our implemn does
this for all tasks in system.

config ARC_CANT_LLSC
def_bool n

menuconfig ARC_CPU_REL_4_10
bool "Enable support for Rel 4.10 features"
default n
Expand All @@ -314,9 +310,7 @@ menuconfig ARC_CPU_REL_4_10
config ARC_HAS_LLSC
bool "Insn: LLOCK/SCOND (efficient atomic ops)"
default y
depends on ARC_CPU_770
# if SMP, enable LLSC ONLY if ARC implementation has coherent atomics
depends on !SMP || ARC_HAS_COH_LLSC
depends on ARC_CPU_770 && !ARC_CANT_LLSC

config ARC_HAS_SWAPE
bool "Insn: SWAPE (endian-swap)"
Expand Down Expand Up @@ -415,13 +409,6 @@ config ARC_DBG_TLB_MISS_COUNT
Counts number of I and D TLB Misses and exports them via Debugfs
The counters can be cleared via Debugfs as well

config CMDLINE
string "Kernel command line to built-in"
default "print-fatal-signals=1"
help
The default command line which will be appended to the optional
u-boot provided command line (see below)

config CMDLINE_UBOOT
bool "Support U-boot kernel command line passing"
default n
Expand All @@ -430,8 +417,8 @@ config CMDLINE_UBOOT
command line from the U-boot environment to the Linux kernel then
switch this option on.
ARC U-boot will setup the cmdline in RAM/flash and set r2 to point
to it. kernel startup code will copy the string into cmdline buffer
and also append CONFIG_CMDLINE.
to it. kernel startup code will append this to DeviceTree
/bootargs provided cmdline args.

config ARC_BUILTIN_DTB_NAME
string "Built in DTB"
Expand All @@ -441,6 +428,10 @@ config ARC_BUILTIN_DTB_NAME

source "kernel/Kconfig.preempt"

menu "Executable file formats"
source "fs/Kconfig.binfmt"
endmenu

endmenu # "ARC Architecture Configuration"

source "mm/Kconfig"
Expand Down
15 changes: 11 additions & 4 deletions trunk/arch/arc/Makefile
Original file line number Diff line number Diff line change
Expand Up @@ -8,6 +8,10 @@

UTS_MACHINE := arc

ifeq ($(CROSS_COMPILE),)
CROSS_COMPILE := arc-elf32-
endif

KBUILD_DEFCONFIG := fpga_defconfig

cflags-y += -mA7 -fno-common -pipe -fno-builtin -D__linux__
Expand Down Expand Up @@ -87,20 +91,23 @@ core-y += arch/arc/
core-y += arch/arc/boot/dts/

core-$(CONFIG_ARC_PLAT_FPGA_LEGACY) += arch/arc/plat-arcfpga/
core-$(CONFIG_ARC_PLAT_TB10X) += arch/arc/plat-tb10x/

drivers-$(CONFIG_OPROFILE) += arch/arc/oprofile/

libs-y += arch/arc/lib/ $(LIBGCC)

boot := arch/arc/boot

#default target for make without any arguements.
KBUILD_IMAGE := bootpImage
KBUILD_IMAGE := bootpImage

all: $(KBUILD_IMAGE)
boot := arch/arc/boot

bootpImage: vmlinux

uImage: vmlinux
boot_targets += uImage uImage.bin uImage.gz

$(boot_targets): vmlinux
$(Q)$(MAKE) $(build)=$(boot) $(boot)/$@

%.dtb %.dtb.S %.dtb.o: scripts
Expand Down
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