VFS: implement sendfile file operation

Currently the sendfile syscalls hardcode assumptions about the
implementation of the read file operations implementation.  Although
it checks for the presence of a readpage address-space operation
filesystems in Linux are free to implement read differently from
the generic version (generic_file_read).  Many filesystems such
as tmpfs, smbfs or xfs chose to implement it differently and need
additional locking, revalidation or checks. 

1 files changed, 1 insertions, 0 deletions

diff --git a/kernel/ksyms.c b/kernel/ksyms.c
index f18263655052..af4e73ca23c0 100644
--- a/kernel/ksyms.c
+++ b/kernel/ksyms.c
@@ -218,6 +218,7 @@ EXPORT_SYMBOL(generic_commit_write);
 EXPORT_SYMBOL(block_truncate_page);
 EXPORT_SYMBOL(generic_block_bmap);
 EXPORT_SYMBOL(generic_file_read);
+EXPORT_SYMBOL(generic_file_sendfile);
 EXPORT_SYMBOL(do_generic_file_read);
 EXPORT_SYMBOL(generic_file_write);
 EXPORT_SYMBOL(generic_file_mmap);