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    ext4: fix punch hole on files with indirect mapping · 4f579ae7
    Lukas Czerner 提交于
    Currently punch hole code on files with direct/indirect mapping has some
    problems which may lead to a data loss. For example (from Jan Kara):
    
    fallocate -n -p 10240000 4096
    
    will punch the range 10240000 - 12632064 instead of the range 1024000 -
    10244096.
    
    Also the code is a bit weird and it's not using infrastructure provided
    by indirect.c, but rather creating it's own way.
    
    This patch fixes the issues as well as making the operation to run 4
    times faster from my testing (punching out 60GB file). It uses similar
    approach used in ext4_ind_truncate() which takes advantage of
    ext4_free_branches() function.
    
    Also rename the ext4_free_hole_blocks() to something more sensible, like
    the equivalent we have for extent mapped files. Call it
    ext4_ind_remove_space().
    
    This has been tested mostly with fsx and some xfstests which are testing
    punch hole but does not require unwritten extents which are not
    supported with direct/indirect mapping. Not problems showed up even with
    1024k block size.
    
    CC: stable@vger.kernel.org
    Signed-off-by: NLukas Czerner <lczerner@redhat.com>
    Signed-off-by: NTheodore Ts'o <tytso@mit.edu>
    4f579ae7
ext4.h 99.6 KB