netfs, 9p, afs, ceph: Use folios

Convert the netfs helper library to use folios throughout, convert the 9p
and afs filesystems to use folios in their file I/O paths and convert the
ceph filesystem to use just enough folios to compile.

With these changes, afs passes -g quick xfstests.

Changes
=======
ver #5:
 - Got rid of folio_end{io,_read,_write}() and inlined the stuff it does
   instead (Willy decided he didn't want this after all).

ver #4:
 - Fixed a bug in afs_redirty_page() whereby it didn't set the next page
   index in the loop and returned too early.
 - Simplified a check in v9fs_vfs_write_folio_locked()[1].
 - Undid a change to afs_symlink_readpage()[1].
 - Used offset_in_folio() in afs_write_end()[1].
 - Changed from using page_endio() to folio_end{io,_read,_write}()[1].

ver #2:
 - Add 9p foliation.

Signed-off-by: David Howells <[email protected]>
Reviewed-by: Jeff Layton <[email protected]>
Tested-by: Jeff Layton <[email protected]>
Tested-by: Dominique Martinet <[email protected]>
Tested-by: [email protected]
cc: Matthew Wilcox (Oracle) <[email protected]>
cc: Marc Dionne <[email protected]>
cc: Ilya Dryomov <[email protected]>
cc: Dominique Martinet <[email protected]>
cc: [email protected]
cc: [email protected]
cc: [email protected]
cc: [email protected]
Link: https://lore.kernel.org/r/YYKa3bfQZxK5/[email protected]/ [1]
Link: https://lore.kernel.org/r/[email protected]/ # rfc
Link: https://lore.kernel.org/r/162877311459.3085614.10601478228012245108.stgit@warthog.procyon.org.uk/
Link: https://lore.kernel.org/r/162981153551.1901565.3124454657133703341.stgit@warthog.procyon.org.uk/
Link: https://lore.kernel.org/r/163005745264.2472992.9852048135392188995.stgit@warthog.procyon.org.uk/ # v2
Link: https://lore.kernel.org/r/163584187452.4023316.500389675405550116.stgit@warthog.procyon.org.uk/ # v3
Link: https://lore.kernel.org/r/163649328026.309189.1124218109373941936.stgit@warthog.procyon.org.uk/ # v4
Link: https://lore.kernel.org/r/163657852454.834781.9265101983152100556.stgit@warthog.procyon.org.uk/ # v5

0 files changed, 0 insertions, 0 deletions