Commit d9e033b3 authored by Trond Myklebust's avatar Trond Myklebust Committed by Linus Torvalds

[PATCH] NFS: Enable NFS_DIRECTIO support

Enable NFS_DIRECTIO support now that it has been fixed...
parent 2d631698
......@@ -1309,6 +1309,30 @@ config NFS_V4
If unsure, say N.
config NFS_DIRECTIO
bool "Allow direct I/O on NFS files (EXPERIMENTAL)"
depends on NFS_FS && EXPERIMENTAL
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
......
......@@ -264,7 +264,7 @@ nfs_file_cred(struct file *file)
/*
* linux/fs/nfs/direct.c
*/
extern int nfs_direct_IO(int, struct file *, const struct iovec *, loff_t,
extern int nfs_direct_IO(int, struct kiocb *, const struct iovec *, loff_t,
unsigned long);
/*
......
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