bdev: Do not return EBUSY if bdev discard races with write
blkdev_fallocate() tries to detect whether a discard raced with an overlapping write by calling invalidate_inode_pages2_range(). However this check can give both false negatives (when writing using direct IO or when writeback already writes out the written pagecache range) and false positives (when write is not actually overlapping but ends in the same page when blocksize < pagesize). This actually causes issues for qemu which is getting confused by EBUSY errors. Fix the problem by removing this conflicting write detection since it is inherently racy and thus of little use anyway. Reported-by:Maxim Levitsky <mlevitsk@redhat.com> CC: "Darrick J. Wong" <darrick.wong@oracle.com> Link: https://lore.kernel.org/qemu-devel/20201111153913.41840-1-mlevitsk@redhat.com Signed-off-by:
Jan Kara <jack@suse.cz> Reviewed-by:
Maxim Levitsky <mlevitsk@redhat.com> Reviewed-by:
Darrick J. Wong <darrick.wong@oracle.com> Reviewed-by:
Christoph Hellwig <hch@lst.de> Signed-off-by:
Jens Axboe <axboe@kernel.dk>
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46bbf653
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