fuse: add FALLOCATE operation

fallocate filesystem operation preallocates media space for the given file.
If fallocate returns success then any subsequent write to the given range
never fails with 'not enough space' error.

Signed-off-by: Anatol Pomozov <anatol.pomozov@gmail.com>
Signed-off-by: Miklos Szeredi <mszeredi@suse.cz>

1 files changed, 33 insertions, 0 deletions

diff --git a/fs/fuse/file.c b/fs/fuse/file.c
index 504e61b7fd75..e3fee88831d4 100644
--- a/fs/fuse/file.c
+++ b/fs/fuse/file.c
@@ -2171,6 +2171,37 @@ fuse_direct_IO(int rw, struct kiocb *iocb, const struct iovec *iov,
         return ret;
 }
 
+long fuse_file_fallocate(struct file *file, int mode, loff_t offset,
+                            loff_t length)
+{
+        struct fuse_file *ff = file->private_data;
+        struct fuse_conn *fc = ff->fc;
+        struct fuse_req *req;
+        struct fuse_fallocate_in inarg = {
+                .fh = ff->fh,
+                .offset = offset,
+                .length = length,
+                .mode = mode
+        };
+        int err;
+
+        req = fuse_get_req(fc);
+        if (IS_ERR(req))
+                return PTR_ERR(req);
+
+        req->in.h.opcode = FUSE_FALLOCATE;
+        req->in.h.nodeid = ff->nodeid;
+        req->in.numargs = 1;
+        req->in.args[0].size = sizeof(inarg);
+        req->in.args[0].value = &inarg;
+        fuse_request_send(fc, req);
+        err = req->out.h.error;
+        fuse_put_request(fc, req);
+
+        return err;
+}
+EXPORT_SYMBOL_GPL(fuse_file_fallocate);
+
 static const struct file_operations fuse_file_operations = {
         .llseek         = fuse_file_llseek,
         .read           = do_sync_read,
@@ -2188,6 +2219,7 @@ static const struct file_operations fuse_file_operations = {
         .unlocked_ioctl = fuse_file_ioctl,
         .compat_ioctl   = fuse_file_compat_ioctl,
         .poll           = fuse_file_poll,
+        .fallocate      = fuse_file_fallocate,
 };
 
 static const struct file_operations fuse_direct_io_file_operations = {
@@ -2204,6 +2236,7 @@ static const struct file_operations fuse_direct_io_file_operations = {
         .unlocked_ioctl = fuse_file_ioctl,
         .compat_ioctl   = fuse_file_compat_ioctl,
         .poll           = fuse_file_poll,
+        .fallocate      = fuse_file_fallocate,
         /* no splice_read */
 };