@@ -298,9 +298,9 @@ Subpage block size
------------------
Most commonly used page sizes are 4KiB, 16KiB and 64KiB. All combinations with
-a 4KiB sector size filesystems are supported. Some features are not compatible
+a 4KiB block size filesystems are supported. Some features are not compatible
with subpage or require another feature to work. Since btrfs-progs 6.7 the default
-sector size is 4KiB as this allows cross-architecture compatibility.
+block size is 4KiB as this allows cross-architecture compatibility.
.. list-table::
:header-rows: 1
@@ -317,9 +317,9 @@ sector size is 4KiB as this allows cross-architecture compatibility.
* - Compression
- :statusok:`partial support`
- Only page-aligned ranges can be compressed
- * - Sectorsize
+ * - Blocksize
- :statusok:`supported`
- - The list of supported sector sizes on a given version can be found
+ - The list of supported block sizes on a given version can be found
in file :file:`/sys/fs/btrfs/features/supported_sectorsizes`
.. _status-zoned:
@@ -2,16 +2,17 @@ Subpage support
===============
Subpage block size support, or just *subpage* for short, is a feature to allow
-using a filesystem that has different size of data block size (*sectorsize*)
+using a filesystem that has different size of data block size
+(*blocksize*, previously called *sectorsize*)
and the host CPU page size. For easier implementation the support was limited
to the exactly same size of the block and page. On x86_64 this is typically
4KiB, but there are other architectures commonly used that make use of larger
pages, like 64KiB on 64bit ARM or PowerPC or 16KiB on Apple Silicon. This means
-filesystems created with 64KiB sector size cannot be mounted on a system with
+filesystems created with 64KiB block size cannot be mounted on a system with
4KiB page size.
-Since btrfs-progs 6.7, filesystems are created with a 4KiB sector size by
-default, though it remains possible to create filesystems with other sector sizes
+Since btrfs-progs 6.7, filesystems are created with a 4KiB block size by
+default, though it remains possible to create filesystems with other block sizes
(such as 64KiB with the "-s 64k" option for :command:`mkfs.btrfs`). This
ensures that new filesystems are compatible across other architecture variants
using larger page sizes.
@@ -21,7 +22,7 @@ Requirements, limitations
The initial subpage support has been added in kernel 5.15. Most features are
already working without problems. On a 64KiB page system, a filesystem with
-4KiB sectorsize can be mounted and used as long as the initial mount succeeds.
+4KiB blocksize can be mounted and used as long as the initial mount succeeds.
Subpage support is used by default for systems with a non-4KiB page size since
btrfs-progs 6.7.
@@ -30,8 +30,8 @@ OPTIONS
-N|--nodesize <SIZE>
set filesystem nodesize, the tree block size in which btrfs stores its metadata.
The default value is 16KiB (16384) or the page size, whichever is bigger.
- Must be a multiple of the sectorsize, but not larger than 65536. See
- :doc:`mkfs.btrfs` for more details.
+ Must be a multiple of the block size (previously called "sector size),
+ but not larger than 65536. See :doc:`mkfs.btrfs` for more details.
-r|--rollback
rollback to the original ext2/3/4 filesystem if possible
-l|--label <LABEL>
@@ -182,8 +182,8 @@ supported_checksums
supported_sectorsizes
(since: 5.13)
- list of values that are accepted as sector sizes (:command:`mkfs.btrfs --sectorsize`) by
- the running kernel
+ list of values that are accepted as block sizes (previously known as
+ "sector size", :command:`mkfs.btrfs --sectorsize|--blocksize`) by the running kernel
supported_rescue_options
(since: 5.11)
@@ -21,8 +21,8 @@ multiple device.
The main reason why you want to have different profiles for data and metadata
is to provide additional protection of the filesystem's metadata when devices fail,
-since a single sector of unrecoverable metadata will break the filesystem,
-while a single sector of lost data can be trivially recovered by deleting the broken file.
+since a single block of unrecoverable metadata will break the filesystem,
+while a single block of lost data can be trivially recovered by deleting the broken file.
Before changing profiles, make sure there is enough unallocated space on
existing drives to create new metadata block groups (for filesystems
@@ -289,10 +289,10 @@ max_inline=<bytes>
Specify the maximum amount of space, that can be inlined in
a metadata b-tree leaf. The value is specified in bytes, optionally
with a K suffix (case insensitive). In practice, this value
- is limited by the filesystem block size (named *sectorsize* at mkfs time),
- and memory page size of the system. In case of sectorsize limit, there's
+ is limited by the filesystem block size (named *blocksize* at mkfs time),
+ and memory page size of the system. In case of blocksize limit, there's
some space unavailable due to b-tree leaf headers. For example, a 4KiB
- sectorsize, maximum size of inline data is about 3900 bytes.
+ blocksize, maximum size of inline data is about 3900 bytes.
Inlining can be completely turned off by specifying 0. This will increase data
block slack if file sizes are much smaller than block size but will reduce
@@ -112,7 +112,7 @@ read_policy
sectorsize
(RO, since: 3.14)
- Shows the sectorsize of the mounted filesystem.
+ Shows the block size (previously called "sector size") of the mounted filesystem.
temp_fsid
To align with other filesystems, with extra mentioning of the older "sectorsize" terminology to reduce confusion. Signed-off-by: Qu Wenruo <wqu@suse.com> --- Documentation/Status.rst | 8 ++++---- Documentation/Subpage.rst | 11 ++++++----- Documentation/btrfs-convert.rst | 4 ++-- Documentation/btrfs-man5.rst | 4 ++-- Documentation/ch-balance-filters.rst | 4 ++-- Documentation/ch-mount-options.rst | 6 +++--- Documentation/ch-sysfs.rst | 2 +- 7 files changed, 20 insertions(+), 19 deletions(-)