mirror of
https://github.com/AetherDroid/android_kernel_samsung_on5xelte.git
synced 2025-09-06 08:18:05 -04:00
Fixed MTP to work with TWRP
This commit is contained in:
awab228
commit
f6dfaef42e
50820 changed files with 20846062 additions and 0 deletions
270
Documentation/filesystems/btrfs.txt
Normal file
270
Documentation/filesystems/btrfs.txt
Normal file
|
|
@ -0,0 +1,270 @@
|
|||
|
||||
BTRFS
|
||||
=====
|
||||
|
||||
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.
|
||||
|
||||
Linux has a wealth of filesystems to choose from, but we are facing a
|
||||
number of challenges with scaling to the large storage subsystems that
|
||||
are becoming common in today's data centers. Filesystems need to scale
|
||||
in their ability to address and manage large storage, and also in
|
||||
their ability to detect, repair and tolerate errors in the data stored
|
||||
on disk. Btrfs is under heavy development, and is not suitable for
|
||||
any uses other than benchmarking and review. The Btrfs disk format is
|
||||
not yet finalized.
|
||||
|
||||
The main Btrfs features include:
|
||||
|
||||
* Extent based file storage (2^64 max file size)
|
||||
* Space efficient packing of small files
|
||||
* Space efficient indexed directories
|
||||
* Dynamic inode allocation
|
||||
* Writable snapshots
|
||||
* Subvolumes (separate internal filesystem roots)
|
||||
* Object level mirroring and striping
|
||||
* Checksums on data and metadata (multiple algorithms available)
|
||||
* Compression
|
||||
* Integrated multiple device support, with several raid algorithms
|
||||
* Online filesystem check (not yet implemented)
|
||||
* Very fast offline filesystem check
|
||||
* Efficient incremental backup and FS mirroring (not yet implemented)
|
||||
* Online filesystem defragmentation
|
||||
|
||||
|
||||
Mount Options
|
||||
=============
|
||||
|
||||
When mounting a btrfs filesystem, the following option are accepted.
|
||||
Options with (*) are default options and will not show in the mount options.
|
||||
|
||||
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.
|
||||
|
||||
noautodefrag(*)
|
||||
autodefrag
|
||||
Disable/enable auto defragmentation.
|
||||
Auto defragmentation detects 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.
|
||||
|
||||
commit=<seconds>
|
||||
Set the interval of periodic commit, 30 seconds by default. Higher
|
||||
values defer data being synced to permanent storage with obvious
|
||||
consequences when the system crashes. The upper bound is not forced,
|
||||
but a warning is printed if it's more than 300 seconds (5 minutes).
|
||||
|
||||
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. Especially useful when trying to mount a multi-device
|
||||
setup as root. May be specified multiple times for multiple devices.
|
||||
|
||||
nodiscard(*)
|
||||
discard
|
||||
Disable/enable discard mount option.
|
||||
Discard issues 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).
|
||||
|
||||
noenospc_debug(*)
|
||||
enospc_debug
|
||||
Disable/enable 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.
|
||||
|
||||
noflushoncommit(*)
|
||||
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.
|
||||
|
||||
acl(*)
|
||||
noacl
|
||||
Enable/disable support for Posix Access Control Lists (ACLs). See the
|
||||
acl(5) manual page for more information about ACLs.
|
||||
|
||||
barrier(*)
|
||||
nobarrier
|
||||
Enable/disable 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 disabled on a device with a volatile
|
||||
(non-battery-backed) write-back cache, nobarrier option will lead to
|
||||
filesystem corruption on a system crash or power loss.
|
||||
|
||||
datacow(*)
|
||||
nodatacow
|
||||
Enable/disable data copy-on-write for newly created files.
|
||||
Nodatacow implies nodatasum, and disables all compression.
|
||||
|
||||
datasum(*)
|
||||
nodatasum
|
||||
Enable/disable data checksumming for newly created files.
|
||||
Datasum implies datacow.
|
||||
|
||||
treelog(*)
|
||||
notreelog
|
||||
Enable/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.
|
||||
|
||||
rescan_uuid_tree
|
||||
Force check and rebuild procedure of the UUID tree. This should not
|
||||
normally be needed.
|
||||
|
||||
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:
|
||||
|
||||
http://vger.kernel.org/vger-lists.html#linux-btrfs
|
||||
|
||||
Mailing list archives are available from gmane:
|
||||
|
||||
http://dir.gmane.org/gmane.comp.file-systems.btrfs
|
||||
|
||||
|
||||
|
||||
IRC
|
||||
===
|
||||
|
||||
Discussion of Btrfs also occurs on the #btrfs channel of the Freenode
|
||||
IRC network.
|
||||
|
||||
|
||||
|
||||
UTILITIES
|
||||
=========
|
||||
|
||||
Userspace tools for creating and manipulating Btrfs file systems are
|
||||
available from the git repository at the following location:
|
||||
|
||||
http://git.kernel.org/?p=linux/kernel/git/mason/btrfs-progs.git
|
||||
git://git.kernel.org/pub/scm/linux/kernel/git/mason/btrfs-progs.git
|
||||
|
||||
These include the following tools:
|
||||
|
||||
* mkfs.btrfs: create a filesystem
|
||||
|
||||
* btrfs: a single tool to manage the filesystems, refer to the manpage for more details
|
||||
|
||||
* 'btrfsck' or 'btrfs check': do a consistency check of the filesystem
|
||||
|
||||
Other tools for specific tasks:
|
||||
|
||||
* btrfs-convert: in-place conversion from ext2/3/4 filesystems
|
||||
|
||||
* btrfs-image: dump filesystem metadata for debugging
|
||||
Loading…
Add table
Add a link
Reference in a new issue