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Filipe Manana
e2844cce75
Currently we use the spinlock inode_lock from struct btrfs_root to serialize access to two different data structures: 1) The delayed inodes xarray (struct btrfs_root::delayed_nodes); 2) The inodes xarray (struct btrfs_root::inodes). Instead of using our own lock, we can use the spinlock that is part of the xarray implementation, by using the xa_lock() and xa_unlock() APIs and using the xarray APIs with the double underscore prefix that don't take the xarray locks and assume the caller is using xa_lock() and xa_unlock(). So remove the spinlock inode_lock from struct btrfs_root and use the corresponding xarray locks. This brings 2 benefits: 1) We reduce the size of struct btrfs_root, from 1336 bytes down to 1328 bytes on a 64 bits release kernel config; 2) We reduce lock contention by not using anymore the same lock for changing two different and unrelated xarrays. Reviewed-by: Qu Wenruo <wqu@suse.com> Signed-off-by: Filipe Manana <fdmanana@suse.com> Reviewed-by: David Sterba <dsterba@suse.com> Signed-off-by: David Sterba <dsterba@suse.com>
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 reStructuredText 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.