NFS: Always enable NFS direct I/O

Since O_DIRECT is a standard feature that is enabled in most distros,
eliminate the CONFIG_NFS_DIRECTIO build option, and change the
fs/nfs/Makefile to always build in the NFS direct I/O engine.

Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>

4 files changed, 1 insertions, 37 deletions

diff --git a/fs/Kconfig b/fs/Kconfig
index d7312825592b..55c1a0374e13 100644
--- a/fs/Kconfig
+++ b/fs/Kconfig
@@ -1637,30 +1637,6 @@ config NFS_V4
 
           If unsure, say N.
 
-config NFS_DIRECTIO
-        bool "Allow direct I/O on NFS files"
-        depends on NFS_FS
-        help
-          This option enables applications to perform uncached I/O on files
-          in NFS file systems using the O_DIRECT open() flag.  When O_DIRECT
-          is set for a file, its data is not cached in the system's page
-          cache.  Data is moved to and from user-level application buffers
-          directly.  Unlike local disk-based file systems, NFS O_DIRECT has
-          no alignment restrictions.
-
-          Unless your program is designed to use O_DIRECT properly, you are
-          much better off allowing the NFS client to manage data caching for
-          you.  Misusing O_DIRECT can cause poor server performance or network
-          storms.  This kernel build option defaults OFF to avoid exposing
-          system administrators unwittingly to a potentially hazardous
-          feature.
-
-          For more details on NFS O_DIRECT, see fs/nfs/direct.c.
-
-          If unsure, say N.  This reduces the size of the NFS client, and
-          causes open() to return EINVAL if a file residing in NFS is
-          opened with the O_DIRECT flag.
-
 config NFSD
         tristate "NFS server support"
         depends on INET
diff --git a/fs/nfs/Makefile b/fs/nfs/Makefile
index df0f41e09885..ac6170c594a3 100644
--- a/fs/nfs/Makefile
+++ b/fs/nfs/Makefile
@@ -5,7 +5,7 @@
 obj-$(CONFIG_NFS_FS) += nfs.o
 
 nfs-y                   := client.o dir.o file.o getroot.o inode.o super.o nfs2xdr.o \
-                           pagelist.o proc.o read.o symlink.o unlink.o \
+                           direct.o pagelist.o proc.o read.o symlink.o unlink.o \
                            write.o namespace.o mount_clnt.o
 nfs-$(CONFIG_ROOT_NFS)  += nfsroot.o
 nfs-$(CONFIG_NFS_V3)    += nfs3proc.o nfs3xdr.o
@@ -14,5 +14,4 @@ nfs-$(CONFIG_NFS_V4)	+= nfs4proc.o nfs4xdr.o nfs4state.o nfs4renewd.o \
                            delegation.o idmap.o \
                            callback.o callback_xdr.o callback_proc.o \
                            nfs4namespace.o
-nfs-$(CONFIG_NFS_DIRECTIO) += direct.o
 nfs-$(CONFIG_SYSCTL) += sysctl.o
diff --git a/fs/nfs/file.c b/fs/nfs/file.c
index ef57a5ae5904..10e8b807e7ff 100644
--- a/fs/nfs/file.c
+++ b/fs/nfs/file.c
@@ -234,10 +234,8 @@ nfs_file_read(struct kiocb *iocb, const struct iovec *iov,
         ssize_t result;
         size_t count = iov_length(iov, nr_segs);
 
-#ifdef CONFIG_NFS_DIRECTIO
         if (iocb->ki_filp->f_flags & O_DIRECT)
                 return nfs_file_direct_read(iocb, iov, nr_segs, pos);
-#endif
 
         dfprintk(VFS, "nfs: read(%s/%s, %lu@%lu)\n",
                 dentry->d_parent->d_name.name, dentry->d_name.name,
@@ -383,9 +381,7 @@ const struct address_space_operations nfs_file_aops = {
         .write_end = nfs_write_end,
         .invalidatepage = nfs_invalidate_page,
         .releasepage = nfs_release_page,
-#ifdef CONFIG_NFS_DIRECTIO
         .direct_IO = nfs_direct_IO,
-#endif
         .launder_page = nfs_launder_page,
 };
 
@@ -443,10 +439,8 @@ static ssize_t nfs_file_write(struct kiocb *iocb, const struct iovec *iov,
         ssize_t result;
         size_t count = iov_length(iov, nr_segs);
 
-#ifdef CONFIG_NFS_DIRECTIO
         if (iocb->ki_filp->f_flags & O_DIRECT)
                 return nfs_file_direct_write(iocb, iov, nr_segs, pos);
-#endif
 
         dfprintk(VFS, "nfs: write(%s/%s(%ld), %lu@%Ld)\n",
                 dentry->d_parent->d_name.name, dentry->d_name.name,
diff --git a/fs/nfs/internal.h b/fs/nfs/internal.h
index 999ad8ee0645..04ae867dddba 100644
--- a/fs/nfs/internal.h
+++ b/fs/nfs/internal.h
@@ -116,13 +116,8 @@ extern void nfs_destroy_readpagecache(void);
 extern int __init nfs_init_writepagecache(void);
 extern void nfs_destroy_writepagecache(void);
 
-#ifdef CONFIG_NFS_DIRECTIO
 extern int __init nfs_init_directcache(void);
 extern void nfs_destroy_directcache(void);
-#else
-#define nfs_init_directcache() (0)
-#define nfs_destroy_directcache() do {} while(0)
-#endif
 
 /* nfs2xdr.c */
 extern int nfs_stat_to_errno(int);