• T
    ext4: add support for extent pre-caching · 7869a4a6
    Theodore Ts'o 提交于
    Add a new fiemap flag which forces the all of the extents in an inode
    to be cached in the extent_status tree.  This is critically important
    when using AIO to a preallocated file, since if we need to read in
    blocks from the extent tree, the io_submit(2) system call becomes
    synchronous, and the AIO is no longer "A", which is bad.
    
    In addition, for most files which have an external leaf tree block,
    the cost of caching the information in the extent status tree will be
    less than caching the entire 4k block in the buffer cache.  So it is
    generally a win to keep the extent information cached.
    Signed-off-by: N"Theodore Ts'o" <tytso@mit.edu>
    7869a4a6
extents.c 133.8 KB