shmem: open code the page cache lookup in shmem_get_folio_gfp

Use the very low level filemap_get_entry helper to look up the entry in
the xarray, and then:

 - don't bother locking the folio if only doing a userfault notification
 - open code locking the page and checking for truncation in a related
   code block

This will allow to eventually remove the FGP_ENTRY flag.

[[email protected]: adjust the new comment line]
  Link: https://lkml.kernel.org/r/[email protected]
Link: https://lkml.kernel.org/r/[email protected]
Signed-off-by: Christoph Hellwig <[email protected]>
Signed-off-by: Hugh Dickins <[email protected]>
Acked-by: Hugh Dickins <[email protected]>
Cc: Andreas Gruenbacher <[email protected]>
Cc: Matthew Wilcox (Oracle) <[email protected]>
Cc: Ryusuke Konishi <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>

0 files changed, 0 insertions, 0 deletions