* Suresh Jayaraman (sjayaraman@xxxxxxx) wrote:
> This patch attempts to add splice writes support. In essence, it just
> calls generic_file_splice_write() after doing a little sanity check.
> This would allow LTTng users that are using NFS to store trace data.
> There could be more applications that could be benefitted too.
>
> I have tested this using the Jens' test program and have found no
> real issues. The test program is inlined below:
>
That's great ! I'll pull it in the LTTng tree so my users can try it.
They currently cannot write LTTng traces to NFS mounts anyway.
Thanks !
Mathieu
> /*
> * splice-out.c: Splice stdout to file
> */
> #include <stdio.h>
> #include <stdlib.h>
> #include <unistd.h>
> #include <fcntl.h>
>
> #define SPLICE_SIZE (64*1024)
>
> int main(int argc, char *argv[])
> {
> int fd;
>
> if (argc < 2) {
> printf("%s: outfile\n", argv[0]);
> return 1;
> }
>
> fd = open(argv[1], O_WRONLY | O_CREAT | O_TRUNC, 0644);
> if (fd < 0) {
> perror("open");
> return 1;
> }
>
> do {
> int ret = splice(STDIN_FILENO, NULL, fd, NULL, SPLICE_SIZE, 0);
>
> if (ret < 0) {
> perror("splice");
> break;
> } else if (ret < SPLICE_SIZE)
> break;
> } while (1);
>
> close(fd);
> return 0;
> }
>
> Compile with -D _GNU_SOURCE and do something like:
> echo "some stuff" | ./splice-out <outfile>
>
> Signed-off-by: Suresh Jayaraman <sjayaraman@xxxxxxx>
> ---
> fs/nfs/file.c | 24 ++++++++++++++++++++++++
> 1 files changed, 24 insertions(+), 0 deletions(-)
>
> diff --git a/fs/nfs/file.c b/fs/nfs/file.c
> index 90f292b..13d6a00 100644
> --- a/fs/nfs/file.c
> +++ b/fs/nfs/file.c
> @@ -47,6 +47,9 @@ static ssize_t nfs_file_splice_read(struct file *filp, loff_t *ppos,
> size_t count, unsigned int flags);
> static ssize_t nfs_file_read(struct kiocb *, const struct iovec *iov,
> unsigned long nr_segs, loff_t pos);
> +static ssize_t nfs_file_splice_write(struct pipe_inode_info *pipe,
> + struct file *filp, loff_t *ppos,
> + size_t count, unsigned int flags);
> static ssize_t nfs_file_write(struct kiocb *, const struct iovec *iov,
> unsigned long nr_segs, loff_t pos);
> static int nfs_file_flush(struct file *, fl_owner_t id);
> @@ -76,6 +79,7 @@ const struct file_operations nfs_file_operations = {
> .lock = nfs_lock,
> .flock = nfs_flock,
> .splice_read = nfs_file_splice_read,
> + .splice_write = nfs_file_splice_write,
> .check_flags = nfs_check_flags,
> .setlease = nfs_setlease,
> };
> @@ -550,6 +554,26 @@ out_swapfile:
> goto out;
> }
>
> +static ssize_t nfs_file_splice_write(struct pipe_inode_info *pipe,
> + struct file *filp, loff_t *ppos,
> + size_t count, unsigned int flags)
> +{
> + struct dentry *dentry = filp->f_path.dentry;
> + struct inode *inode = dentry->d_inode;
> +
> + dprintk("NFS splice_write(%s/%s, %lu@%Lu)\n",
> + dentry->d_parent->d_name.name, dentry->d_name.name,
> + (unsigned long) count, (unsigned long long) *ppos);
> +
> + if (IS_SWAPFILE(inode)) {
> + printk(KERN_INFO "NFS: attempt to write to active swap"
> + "file!\n");
> + return -EBUSY;
> + }
> +
> + return generic_file_splice_write(pipe, filp, ppos, count, flags);
> +}
> +
> static int do_getlk(struct file *filp, int cmd, struct file_lock *fl)
> {
> struct inode *inode = filp->f_mapping->host;
>
--
Mathieu Desnoyers
OpenPGP key fingerprint: 8CD5 52C3 8E3C 4140 715F BA06 3F25 A8FE 3BAE 9A68
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