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    Subject[PATCH 0/7 v3] Push file_update_time() into .page_mkwrite

    to provide reliable support for filesystem freezing, filesystems need to have
    complete control over when metadata is changed. In particular,
    file_update_time() calls from page fault code make it impossible for
    filesystems to prevent inodes from being dirtied while the filesystem is

    To fix the issue, this patch set changes page fault code to call
    file_update_time() only when ->page_mkwrite() callback is not provided. If the
    callback is provided, it is the responsibility of the filesystem to perform
    update of i_mtime / i_ctime if needed. We also push file_update_time() call
    to all existing ->page_mkwrite() implementations if the time update does not
    obviously happen by other means. This is including __block_page_mkwrite() so
    filesystems using it are handled. If you know your filesystem does not need
    update of modification times in ->page_mkwrite() handler, please speak up and
    I'll drop the patch for your filesystem.

    As a side note, an alternative would be to remove calls of file_update_time()
    from page fault code altogether and require all filesystems needing it to do
    that in their ->page_mkwrite() implementation. That is certainly possible
    although maybe slightly inefficient and would require auditting 100+
    vm_operations_structs *shiver*.

    Changes since v1:
    * Dropped patches for filesystems which don't need them
    * Added some acks
    * Improved sysfs patch by Alex Elder's suggestion

    Changes since v2:
    * Dropped patches for more filesystems

    Andrew, would you be willing to merge these patches via your tree? This seems
    to be a final version.


    CC: Jaya Kumar <>
    CC: Sage Weil <>
    CC: Eric Van Hensbergen <>
    CC: Ron Minnich <>
    CC: Latchesar Ionkov <>
    CC: Steven Whitehouse <>
    CC: Greg Kroah-Hartman <>

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