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Extent freeing neeeds to be able to avoid a busy extent deadlock when the transaction itself holds the only busy extents in the allocation group. This may occur if we have an EFI that contains multiple extents to be freed, and the freeing the second intent requires the space the first extent free released to expand the AGFL. If we block on the busy extent at this point, we deadlock. We hold a dirty transaction that contains a entire atomic extent free operations within it, so if we can abort the extent free operation and commit the progress that we've made, the busy extent can be resolved by a log force. Hence we can restart the aborted extent free with a new transaction and continue to make progress without risking deadlocks. To enable this, we need the EFI processing code to be able to handle an -EAGAIN error to tell it to commit the current transaction and retry again. This mechanism is already built into the defer ops processing (used bythe refcount btree modification intents), so there's relatively little handling we need to add to the EFI code to enable this. Signed-off-by: Dave Chinner <dchinner@redhat.com> Reviewed-by: Darrick J. Wong <djwong@kernel.org> Signed-off-by: Darrick J. Wong <djwong@kernel.org> Reviewed-by: Chandan Babu R <chandan.babu@oracle.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 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.