07afd3173d
Take mp->m_perag_lock for deletions from the perag radix tree in xfs_initialize_perag to prevent racing with tagging operations. Lookups are fine - they are RCU protected so already deal with the tree changing shape underneath the lookup - but tagging operations require the tree to be stable while the tags are propagated back up to the root. Right now there's nothing stopping radix tree tagging from operating while a growfs operation is progress and adding/removing new entries into the radix tree. Hence we can have traversals that require a stable tree occurring at the same time we are removing unused entries from the radix tree which causes the shape of the tree to change. Likely this hasn't caused a problem in the past because we are only doing append addition and removal so the active AG part of the tree is not changing shape, but that doesn't mean it is safe. Just making the radix tree modifications serialise against each other is obviously correct. Signed-off-by: Long Li <leo.lilong@huawei.com> Reviewed-by: Christoph Hellwig <hch@lst.de> Reviewed-by: "Darrick J. Wong" <djwong@kernel.org> Signed-off-by: Chandan Babu R <chandanbabu@kernel.org>
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.