fs: new cont helpers

Rework the generic block "cont" routines to handle the new aops.  Supporting
cont_prepare_write would take quite a lot of code to support, so remove it
instead (and we later convert all filesystems to use it).

write_begin gets passed AOP_FLAG_CONT_EXPAND when called from
generic_cont_expand, so filesystems can avoid the old hacks they used.

Signed-off-by: Nick Piggin <npiggin@suse.de>
Cc: OGAWA Hirofumi <hirofumi@mail.parknet.co.jp>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

1 files changed, 5 insertions, 0 deletions

diff --git a/mm/filemap.c b/mm/filemap.c
index ca04226bf1de..195339b27e9a 100644
--- a/mm/filemap.c
+++ b/mm/filemap.c
@@ -1684,6 +1684,7 @@ size_t iov_iter_copy_from_user_atomic(struct page *page,
 
         return copied;
 }
+EXPORT_SYMBOL(iov_iter_copy_from_user_atomic);
 
 /*
  * This has the same sideeffects and return value as
@@ -1710,6 +1711,7 @@ size_t iov_iter_copy_from_user(struct page *page,
         kunmap(page);
         return copied;
 }
+EXPORT_SYMBOL(iov_iter_copy_from_user);
 
 static void __iov_iter_advance_iov(struct iov_iter *i, size_t bytes)
 {
@@ -1741,6 +1743,7 @@ void iov_iter_advance(struct iov_iter *i, size_t bytes)
         __iov_iter_advance_iov(i, bytes);
         i->count -= bytes;
 }
+EXPORT_SYMBOL(iov_iter_advance);
 
 /*
  * Fault in the first iovec of the given iov_iter, to a maximum length
@@ -1757,6 +1760,7 @@ int iov_iter_fault_in_readable(struct iov_iter *i, size_t bytes)
         bytes = min(bytes, i->iov->iov_len - i->iov_offset);
         return fault_in_pages_readable(buf, bytes);
 }
+EXPORT_SYMBOL(iov_iter_fault_in_readable);
 
 /*
  * Return the count of just the current iov_iter segment.
@@ -1769,6 +1773,7 @@ size_t iov_iter_single_seg_count(struct iov_iter *i)
         else
                 return min(i->count, iov->iov_len - i->iov_offset);
 }
+EXPORT_SYMBOL(iov_iter_single_seg_count);
 
 /*
  * Performs necessary checks before doing a write