The basic idea is simple. Assume a middle tree node A is shared and
its referencing fs/file tree root ids are 5, 258 and 260, then we
only check node A in the tree who has the smallest root id. That means
in this case, when checking root tree(5), we check inode A, for root
tree 258 and 260, we can just skip it.
Notice even with this patch, we still may visit a shared node or leaf
multiple times. This happens when a inode metadata occupies multiple
leaves.
leaf_A leaf_B
When checking inode item in leaf_A, assume inode[512] have file extents
in leaf_B, and leaf_B is shared. In the case, for inode[512], we must
visit leaf_B to have inode item checked. After finishing inode[512] check,
here we walk down tree root to leaf_B to check whether node or leaf
is shared, if some node or leaf is shared, we can just skip it and below
nodes or leaf's check.
I also fill a disk partition with linux source codes and create 3
snapshots in it. Before this patch, it averagely took 46s to finish one
btrfsck execution, with this patch, it averagely took 15s.
Signed-off-by: Wang Xiaoguang <wangxg.fnst@cn.fujitsu.com>
Signed-off-by: Qu Wenruo <quwenruo@cn.fujitsu.com>
Signed-off-by: David Sterba <dsterba@suse.com>
Userspace utilities to manage btrfs filesystems.
License: GPLv2.
Btrfs is a copy on write (COW) filesystem for Linux aimed at implementing
advanced features while focusing on fault tolerance, repair and easy
administration.
This repository hosts following utilities:
btrfs — the main administration tool (manual page)
mkfs.btrfs — utility to create the filesystem (manual page)
See INSTALL for build instructions and tests/README.md for
testing information.
Release cycle
The major version releases are time-based and follow the cycle of the linux
kernel releases. The cycle usually takes 2 months. A minor version releases may
happen in the meantime if there are bug fixes or minor useful improvements
queued.
The release tags are signed with a GPG key ID F2B4 1200 C54E FB30 380C 1756 C565 D5F9 D76D 583B,
release tarballs are hosted at kernel.org.
See file CHANGES or changelogs on wiki.
Reporting bugs
There are several ways, each has its own specifics and audience that can give
feedback or work on a fix.
bugzilla.kernel.org -- (requires
registration), set the product to Filesystems and component Btrfs, please put
'btrfs-progs' into the subject so it's clear that it's not a kernel bug
report
to the mailing list linux-btrfs@vger.kernel.org -- (not required to
subscribe), beware that the mail might get overlooked in other traffic
IRC (irc.freenode.net #btrfs) -- good for discussions eg. if a bug is already
known, but reports could miss developers' attention
Development
The patch submissions, development or general discussions take place at
linux-btrfs@vger.kernel.org mailinglist, subsciption is not required to post.
The GitHub pull requests will not be accepted directly, the preferred way is to
send patches to the mailinglist instead. You can link to a branch in any git
repository if the mails do not make it to the mailinglist or just for
convenience (makes it easier to test).
The development model of btrfs-progs shares a lot with the kernel model. The
github way is different in some ways. We, the upstream community, expect that
the patches meet some criteria (often lacking in github contributions):
one logical change per patch: eg. not mixing bugfixes, cleanups, features
etc., sometimes it's not clear and will be usually pointed out during reviews
proper subject line: eg. prefix with btrfs-progs: subpart, ... ,
descriptive yet not too long, see git log --oneline for some inspiration
proper changelog: the changelogs are often missing or lacking explanation why
the change was made, or how is something broken, what are user-visible
effects of the bug or the fix, how does an improvement help or the intended
usecase
the Signed-off-by line: this documents who authored the change, you can read
more about the The Developer's Certificate of Originhere (chapter 11)
Exceptions: documentation fixes or updates do not need much explanation so
sticking to the above rules is not necessary. Github pull requests are OK.
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