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authorDave Chinner <david@fromorbit.com>2012-04-23 15:58:43 +1000
committerBen Myers <bpm@sgi.com>2012-05-14 16:20:35 -0500
commit6ffc4db5de61d36e969a26bc94509c59246c81f8 (patch)
tree44f5850d4892f017d15b3ac0a0c9bd1f35cacc8d /block
parent4c2d542f2e786537db33b613d5199dc6d69a96da (diff)
downloadlinux-6ffc4db5de61d36e969a26bc94509c59246c81f8.tar.bz2
xfs: page type check in writeback only checks last buffer
xfs_is_delayed_page() checks to see if a page has buffers matching the given IO type passed in. It does so by walking the buffer heads on the page and checking if the state flags match the IO type. However, the "acceptable" variable that is calculated is overwritten every time a new buffer is checked. Hence if the first buffer on the page is of the right type, this state is lost if the second buffer is not of the correct type. This means that xfs_aops_discard_page() may not discard delalloc regions when it is supposed to, and xfs_convert_page() may not cluster IO as efficiently as possible. This problem only occurs on filesystems with a block size smaller than page size. Also, rename xfs_is_delayed_page() to xfs_check_page_type() to better describe what it is doing - it is not delalloc specific anymore. The problem was first noticed by Peter Watkins. Signed-off-by: Dave Chinner <dchinner@redhat.com> Reviewed-by: Christoph Hellwig <hch@lst.de> Reviewed-by: Mark Tinguely <tinguely@sgi.com> Signed-off-by: Ben Myers <bpm@sgi.com>
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