From: Jens Axboe Date: Thu, 7 Jun 2007 07:39:42 +0000 (+0200) Subject: splice: __generic_file_splice_read: fix read/truncate race X-Git-Tag: v2.6.22-rc5~56^2 X-Git-Url: http://git.openpandora.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=620a324b744a7d66c3c45a83042f8e7fc9fc5a04;p=pandora-kernel.git splice: __generic_file_splice_read: fix read/truncate race Original patch and description from Neil Brown , merged and adapted to splice branch by me. Neils text follows: __generic_file_splice_read() currently samples the i_size at the start and doesn't do so again unless it needs to call ->readpage to load a page. After ->readpage it has to re-sample i_size as a truncate may have caused that page to be filled with zeros, and the read() call should not see these. However there are other activities that might cause ->readpage to be called on a page between the time that __generic_file_splice_read() samples i_size and when it finds that it has an uptodate page. These include at least read-ahead and possibly another thread performing a read So we must sample i_size *after* it has an uptodate page. Thus the current sampling at the start and after a read can be replaced with a sampling before page addition into spd. Signed-off-by: Jens Axboe --- Reading git-diff-tree failed