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Dio writes can update i_size in btrfs_get_blocks_direct when it writes to offset beyond EOF so that endio can update disk_i_size correctly (because we don't udpate disk_i_size beyond i_size). However, when truncating down a file, we firstly update i_size and then wait for in-flight lockless dio reads/writes, according to the above, i_size may have been changed in dio writes, and file extents don't get truncated. For lockless dio writes are always overwrites, i_size is not supposed to be changed, so this adds a check to filter out this case. The race could be reproduced by fstests/generic/299 with patch "Btrfs: fix btrfs_ordered_update_i_size to update disk_i_size properly" applied. Signed-off-by: Liu Bo <bo.li.liu@oracle.com> Signed-off-by: David Sterba <dsterba@suse.com>
Linux kernel ============ This file was moved to Documentation/admin-guide/README.rst Please notice that there are several guides for kernel developers and users. These guides can be rendered in a number of formats, like HTML and PDF. In order to build the documentation, use ``make htmldocs`` or ``make pdfdocs``. There are various text files in the Documentation/ subdirectory, several of them using the Restructured Text markup notation. See Documentation/00-INDEX for a list of what is contained in each file. 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.