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--- a/fs/Kconfig
+++ b/fs/Kconfig
@@ -62,6 +62,11 @@ config FILE_LOCKING
for filesystems like NFS and for the flock() system
call. Disabling this option saves about 11k.
+config DIRECT_IO
+ bool "Enable O_DIRECT support" if EXPERT
+ depends on BLOCK
+ default y
+
source "fs/notify/Kconfig"
source "fs/quota/Kconfig"
--- a/fs/Makefile
+++ b/fs/Makefile
@@ -14,7 +14,8 @@ obj-y := open.o read_write.o file_table.
stack.o fs_struct.o statfs.o fs_pin.o
ifeq ($(CONFIG_BLOCK),y)
-obj-y += buffer.o block_dev.o direct-io.o mpage.o
+obj-y += buffer.o block_dev.o mpage.o
+obj-$(CONFIG_DIRECT_IO) += direct-io.o
else
obj-y += no-block.o
endif
--- a/include/linux/fs.h
+++ b/include/linux/fs.h
@@ -2529,12 +2529,25 @@ enum {
DIO_ASYNC_EXTEND = 0x04,
};
+#ifdef CONFIG_DIRECT_IO
void dio_end_io(struct bio *bio, int error);
ssize_t __blockdev_direct_IO(int rw, struct kiocb *iocb, struct inode *inode,
struct block_device *bdev, struct iov_iter *iter, loff_t offset,
get_block_t get_block, dio_iodone_t end_io,
dio_submit_t submit_io, int flags);
+#else
+static inline void dio_end_io(struct bio *bio, int error)
+{
+}
+static inline ssize_t __blockdev_direct_IO(int rw, struct kiocb *iocb, struct inode *inode,
+ struct block_device *bdev, struct iov_iter *iter, loff_t offset,
+ get_block_t get_block, dio_iodone_t end_io,
+ dio_submit_t submit_io, int flags)
+{
+ return -EOPNOTSUPP;
+}
+#endif
static inline ssize_t blockdev_direct_IO(int rw, struct kiocb *iocb,
struct inode *inode, struct iov_iter *iter, loff_t offset,
--- a/fs/fcntl.c
+++ b/fs/fcntl.c
@@ -52,8 +52,10 @@ static int setfl(int fd, struct file * f
arg |= O_NONBLOCK;
if (arg & O_DIRECT) {
+#ifdef CONFIG_DIRECT_IO
if (!filp->f_mapping || !filp->f_mapping->a_ops ||
!filp->f_mapping->a_ops->direct_IO)
+#endif
return -EINVAL;
}
--- a/fs/open.c
+++ b/fs/open.c
@@ -655,9 +655,12 @@ int open_check_o_direct(struct file *f)
{
/* NB: we're sure to have correct a_ops only after f_op->open */
if (f->f_flags & O_DIRECT) {
+#ifdef CONFIG_DIRECT_IO
if (!f->f_mapping->a_ops ||
((!f->f_mapping->a_ops->direct_IO) &&
- (!f->f_mapping->a_ops->get_xip_mem))) {
+ (!f->f_mapping->a_ops->get_xip_mem)))
+#endif
+ {
return -EINVAL;
}
}
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