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    ext4: enable "punch hole" functionality · a4bb6b64
    Allison Henderson 提交于
    This patch adds new routines: "ext4_punch_hole" "ext4_ext_punch_hole"
    and "ext4_ext_check_cache"
    
    fallocate has been modified to call ext4_punch_hole when the punch hole
    flag is passed.  At the moment, we only support punching holes in
    extents, so this routine is pretty much a wrapper for the ext4_ext_punch_hole
    routine.
    
    The ext4_ext_punch_hole routine first completes all outstanding writes
    with the associated pages, and then releases them.  The unblock
    aligned data is zeroed, and all blocks in between are punched out.
    
    The ext4_ext_check_cache routine is very similar to ext4_ext_in_cache
    except it accepts a ext4_ext_cache parameter instead of a ext4_extent
    parameter.  This routine is used by ext4_ext_punch_hole to check and
    see if a block in a hole that has been cached.  The ext4_ext_cache
    parameter is necessary because the members ext4_extent structure are
    not large enough to hold a 32 bit value.  The existing
    ext4_ext_in_cache routine has become a wrapper to this new function.
    
    [ext4 punch hole patch series 5/5 v7] 
    Signed-off-by: NAllison Henderson <achender@us.ibm.com>
    Signed-off-by: N"Theodore Ts'o" <tytso@mit.edu>
    Reviewed-by: NMingming Cao <cmm@us.ibm.com>
    a4bb6b64
extents.c 113.5 KB