fuse: add helper for asynchronous writes

This patch adds a new helper function fuse_write_fill() which makes it
possible to send WRITE requests asynchronously.

A new flag for WRITE requests is also added which indicates that this a write
from the page cache, and not a "normal" file write.

This patch is in preparation for writable mmap support.

Signed-off-by: Miklos Szeredi <mszeredi@suse.cz>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

diff --git a/fs/fuse/file.c b/fs/fuse/file.c
index c4c59c7d0038cfc2ecfa50ca3d8d33f4cb6dbd94..2b589de044e8be904b4b635c2155db9926188931 100644 (file)
--- a/fs/fuse/file.c
+++ b/fs/fuse/file.c
@@ -443,30 +443,37 @@ out:
        return err;
 }
 
-static size_t fuse_send_write(struct fuse_req *req, struct file *file,
-                             struct inode *inode, loff_t pos, size_t count)
+static void fuse_write_fill(struct fuse_req *req, struct fuse_file *ff,
+                           struct inode *inode, loff_t pos, size_t count,
+                           int writepage)
 {
-       struct fuse_conn *fc = get_fuse_conn(inode);
-       struct fuse_file *ff = file->private_data;
-       struct fuse_write_in inarg;
-       struct fuse_write_out outarg;
+       struct fuse_write_in *inarg = &req->misc.write.in;
+       struct fuse_write_out *outarg = &req->misc.write.out;
 
-       memset(&inarg, 0, sizeof(struct fuse_write_in));
-       inarg.fh = ff->fh;
-       inarg.offset = pos;
-       inarg.size = count;
+       memset(inarg, 0, sizeof(struct fuse_write_in));
+       inarg->fh = ff->fh;
+       inarg->offset = pos;
+       inarg->size = count;
+       inarg->write_flags = writepage ? FUSE_WRITE_CACHE : 0;
        req->in.h.opcode = FUSE_WRITE;
        req->in.h.nodeid = get_node_id(inode);
        req->in.argpages = 1;
        req->in.numargs = 2;
        req->in.args[0].size = sizeof(struct fuse_write_in);
-       req->in.args[0].value = &inarg;
+       req->in.args[0].value = inarg;
        req->in.args[1].size = count;
        req->out.numargs = 1;
        req->out.args[0].size = sizeof(struct fuse_write_out);
-       req->out.args[0].value = &outarg;
+       req->out.args[0].value = outarg;
+}
+
+static size_t fuse_send_write(struct fuse_req *req, struct file *file,
+                             struct inode *inode, loff_t pos, size_t count)
+{
+       struct fuse_conn *fc = get_fuse_conn(inode);
+       fuse_write_fill(req, file->private_data, inode, pos, count, 0);
        request_send(fc, req);
-       return outarg.size;
+       return req->misc.write.out.size;
 }
 
 static int fuse_write_begin(struct file *file, struct address_space *mapping,

diff --git a/fs/fuse/fuse_i.h b/fs/fuse/fuse_i.h
index 5657cca0d0cb959a9ac8ff1a728b5f541682239f..8b64a630e7589c1592aa808c40e3b011588a4822 100644 (file)
--- a/fs/fuse/fuse_i.h
+++ b/fs/fuse/fuse_i.h
@@ -219,6 +219,10 @@ struct fuse_req {
                struct fuse_init_in init_in;
                struct fuse_init_out init_out;
                struct fuse_read_in read_in;
+               struct {
+                       struct fuse_write_in in;
+                       struct fuse_write_out out;
+               } write;
                struct fuse_lk_in lk_in;
        } misc;
 

diff --git a/include/linux/fuse.h b/include/linux/fuse.h
index 015a8b15a388789da2d571fbe45fdd5da61af009..6f4a31266cd586a2eefe9fe2dd46fb5b2c3b0993 100644 (file)
--- a/include/linux/fuse.h
+++ b/include/linux/fuse.h
@@ -119,6 +119,13 @@ struct fuse_file_lock {
  */
 #define FUSE_LK_FLOCK          (1 << 0)
 
+/**
+ * WRITE flags
+ *
+ * FUSE_WRITE_CACHE: delayed write from page cache, file handle is guessed
+ */
+#define FUSE_WRITE_CACHE       (1 << 0)
+
 enum fuse_opcode {
        FUSE_LOOKUP        = 1,
        FUSE_FORGET        = 2,  /* no reply */