89b1f55a29
xfs_dialloc_select_ag() does a lot of repetitive work. It first calls xfs_ialloc_ag_select() to select the AG to start allocation attempts in, which can do up to two entire loops across the perags that inodes can be allocated in. This is simply checking if there is spce available to allocate inodes in an AG, and it returns when it finds the first candidate AG. xfs_dialloc_select_ag() then does it's own iterative walk across all the perags locking the AGIs and trying to allocate inodes from the locked AG. It also doesn't limit the search to mp->m_maxagi, so it will walk all AGs whether they can allocate inodes or not. Hence if we are really low on inodes, we could do almost 3 entire walks across the whole perag range before we find an allocation group we can allocate inodes in or report ENOSPC. Because xfs_ialloc_ag_select() returns on the first candidate AG it finds, we can simply do these checks directly in xfs_dialloc_select_ag() before we lock and try to allocate inodes. This reduces the inode allocation pass down to 2 perag sweeps at most - one for aligned inode cluster allocation and if we can't allocate full, aligned inode clusters anywhere we'll do another pass trying to do sparse inode cluster allocation. This also removes a big chunk of duplicate code. Signed-off-by: Dave Chinner <dchinner@redhat.com> Reviewed-by: Darrick J. Wong <djwong@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.