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763e4cdc0f
iomap writeback mapping failure only calls into ->discard_page() if the current page has not been added to the ioend. Accordingly, the XFS callback assumes a full page discard and invalidation. This is problematic for sub-page block size filesystems where some portion of a page might have been mapped successfully before a failure to map a delalloc block occurs. ->discard_page() is not called in that error scenario and the bio is explicitly failed by iomap via the error return from ->prepare_ioend(). As a result, the filesystem leaks delalloc blocks and corrupts the filesystem block counters. Since XFS is the only user of ->discard_page(), tweak the semantics to invoke the callback unconditionally on mapping errors and provide the file offset that failed to map. Update xfs_discard_page() to discard the corresponding portion of the file and pass the range along to iomap_invalidatepage(). The latter already properly handles both full and sub-page scenarios by not changing any iomap or page state on sub-page invalidations. Signed-off-by: Brian Foster <bfoster@redhat.com> Reviewed-by: Christoph Hellwig <hch@lst.de> Reviewed-by: Darrick J. Wong <darrick.wong@oracle.com> Signed-off-by: Darrick J. Wong <darrick.wong@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.