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Linux kernel source tree
2280d425ba
During fiemap, when walking backreferences to determine if a b+tree
node/leaf is shared, we may find a tree block (leaf or node) for which
two parents were added to the references ulist. This happens if we get
for example one direct ref (shared tree block ref) and one indirect ref
(non-shared tree block ref) for the tree block at the current level,
which can happen during relocation.
In that case the fiemap path cache can not be used since it's meant for
a single path, with one tree block at each possible level, so having
multiple references for a tree block at any level may result in getting
the level counter exceed BTRFS_MAX_LEVEL and eventually trigger the
warning:
WARN_ON_ONCE(level >= BTRFS_MAX_LEVEL)
at lookup_backref_shared_cache() and at store_backref_shared_cache().
This is harmless since the code ignores any level >= BTRFS_MAX_LEVEL, the
warning is there just to catch any unexpected case like the one described
above. However if a user finds this it may be scary and get reported.
So just ignore the path cache once we find a tree block for which there
are more than one reference, which is the less common case, and update
the cache with the sharedness check result for all levels below the level
for which we found multiple references.
Reported-by: Jarno Pelkonen <jarno.pelkonen@gmail.com>
Link: https://lore.kernel.org/linux-btrfs/CAKv8qLmDNAGJGCtsevxx_VZ_YOvvs1L83iEJkTgyA4joJertng@mail.gmail.com/
Fixes:
|
||
|---|---|---|
| arch | ||
| block | ||
| certs | ||
| crypto | ||
| Documentation | ||
| drivers | ||
| fs | ||
| include | ||
| init | ||
| io_uring | ||
| ipc | ||
| kernel | ||
| lib | ||
| LICENSES | ||
| mm | ||
| net | ||
| rust | ||
| samples | ||
| scripts | ||
| security | ||
| sound | ||
| tools | ||
| usr | ||
| virt | ||
| .clang-format | ||
| .cocciconfig | ||
| .get_maintainer.ignore | ||
| .gitattributes | ||
| .gitignore | ||
| .mailmap | ||
| .rustfmt.toml | ||
| COPYING | ||
| CREDITS | ||
| Kbuild | ||
| Kconfig | ||
| MAINTAINERS | ||
| Makefile | ||
| README | ||
Linux kernel
============
There are several guides for kernel developers and users. These guides can
be rendered in a number of formats, like HTML and PDF. Please read
Documentation/admin-guide/README.rst first.
In order to build the documentation, use ``make htmldocs`` or
``make pdfdocs``. The formatted documentation can also be read online at:
https://www.kernel.org/doc/html/latest/
There are various text files in the Documentation/ subdirectory,
several of them using the Restructured Text markup notation.
Please read the Documentation/process/changes.rst file, as it contains the
requirements for building and running the kernel, and information about
the problems which may result by upgrading your kernel.