mm/filemap: don't decrease mmap_miss when folio has workingset flag

If there are too many folios that are recently evicted in a file, then
they will probably continue to be evicted.  In such situation, there is no
positive effect to read-ahead this file since it is only a waste of IO.

The mmap_miss is increased in do_sync_mmap_readahead() and decreased in
both do_async_mmap_readahead() and filemap_map_pages().  In order to skip
read-ahead in above scenario, the mmap_miss have to increased exceed
MMAP_LOTSAMISS.  This can be done by stop decreased mmap_miss when folio
has workingset flag.  The async path is not to care because in above
scenario, it's hard to run into the async path.

[[email protected]: add comments]
  Link: https://lkml.kernel.org/r/[email protected]
Link: https://lkml.kernel.org/r/[email protected]
Signed-off-by: Liu Shixin <[email protected]>
Reviewed-by: Jan Kara <[email protected]>
Cc: Al Viro <[email protected]>
Cc: Christian Brauner <[email protected]>
Cc: Jinjiang Tu <[email protected]>
Cc: Matthew Wilcox (Oracle) <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>

0 files changed, 0 insertions, 0 deletions