netfs: do not unlock and put the folio twice

check_write_begin() will unlock and put the folio when return
non-zero.  So we should avoid unlocking and putting it twice in
netfs layer.

Change the way ->check_write_begin() works in the following two ways:

 (1) Pass it a pointer to the folio pointer, allowing it to unlock and put
     the folio prior to doing the stuff it wants to do, provided it clears
     the folio pointer.

 (2) Change the return values such that 0 with folio pointer set means
     continue, 0 with folio pointer cleared means re-get and all error
     codes indicating an error (no special treatment for -EAGAIN).

[ bagasdotme: use Sphinx code text syntax for *foliop pointer ]

Cc: [email protected]
Link: https://tracker.ceph.com/issues/56423
Link: https://lore.kernel.org/r/[email protected]
Co-developed-by: David Howells <[email protected]>
Signed-off-by: Xiubo Li <[email protected]>
Signed-off-by: David Howells <[email protected]>
Signed-off-by: Bagas Sanjaya <[email protected]>
Signed-off-by: Ilya Dryomov <[email protected]>

0 files changed, 0 insertions, 0 deletions