9P: introduction of a new cache=mmap model.

 - Add cache=mmap option
 - Make mmap read-write while keeping it as synchronous as possible
 - Build writeback fid on mmap creation if it is writable

Signed-off-by: Dominique Martinet <dominique.martinet@cea.fr>
Signed-off-by: Eric Van Hensbergen <ericvh@gmail.com>

1 files changed, 15 insertions, 7 deletions

diff --git a/fs/9p/vfs_inode.c b/fs/9p/vfs_inode.c
index af7d531bdecd..bb7991c7e5c7 100644
--- a/fs/9p/vfs_inode.c
+++ b/fs/9p/vfs_inode.c
@@ -299,15 +299,22 @@ int v9fs_init_inode(struct v9fs_session_info *v9ses,
         case S_IFREG:
                 if (v9fs_proto_dotl(v9ses)) {
                         inode->i_op = &v9fs_file_inode_operations_dotl;
-                        if (v9ses->cache)
+                        if (v9ses->cache == CACHE_LOOSE ||
+                            v9ses->cache == CACHE_FSCACHE)
                                 inode->i_fop =
                                         &v9fs_cached_file_operations_dotl;
+                        else if (v9ses->cache == CACHE_MMAP)
+                                inode->i_fop = &v9fs_mmap_file_operations_dotl;
                         else
                                 inode->i_fop = &v9fs_file_operations_dotl;
                 } else {
                         inode->i_op = &v9fs_file_inode_operations;
-                        if (v9ses->cache)
-                                inode->i_fop = &v9fs_cached_file_operations;
+                        if (v9ses->cache == CACHE_LOOSE ||
+                            v9ses->cache == CACHE_FSCACHE)
+                                inode->i_fop =
+                                        &v9fs_cached_file_operations;
+                        else if (v9ses->cache == CACHE_MMAP)
+                                inode->i_fop = &v9fs_mmap_file_operations;
                         else
                                 inode->i_fop = &v9fs_file_operations;
                 }
@@ -810,7 +817,7 @@ struct dentry *v9fs_vfs_lookup(struct inode *dir, struct dentry *dentry,
          * unlink. For cached mode create calls request for new
          * inode. But with cache disabled, lookup should do this.
          */
-        if (v9ses->cache)
+        if (v9ses->cache == CACHE_LOOSE || v9ses->cache == CACHE_FSCACHE)
                 inode = v9fs_get_inode_from_fid(v9ses, fid, dir->i_sb);
         else
                 inode = v9fs_get_new_inode_from_fid(v9ses, fid, dir->i_sb);
@@ -876,7 +883,8 @@ v9fs_vfs_atomic_open(struct inode *dir, struct dentry *dentry,
         v9fs_invalidate_inode_attr(dir);
         v9inode = V9FS_I(dentry->d_inode);
         mutex_lock(&v9inode->v_mutex);
-        if (v9ses->cache && !v9inode->writeback_fid &&
+        if ((v9ses->cache == CACHE_LOOSE || v9ses->cache == CACHE_FSCACHE) &&
+            !v9inode->writeback_fid &&
             ((flags & O_ACCMODE) != O_RDONLY)) {
                 /*
                  * clone a fid and add it to writeback_fid
@@ -899,7 +907,7 @@ v9fs_vfs_atomic_open(struct inode *dir, struct dentry *dentry,
                 goto error;
 
         file->private_data = fid;
-        if (v9ses->cache)
+        if (v9ses->cache == CACHE_LOOSE || v9ses->cache == CACHE_FSCACHE)
                 v9fs_cache_inode_set_cookie(dentry->d_inode, file);
 
         *opened |= FILE_CREATED;
@@ -1477,7 +1485,7 @@ int v9fs_refresh_inode(struct p9_fid *fid, struct inode *inode)
          */
         i_size = inode->i_size;
         v9fs_stat2inode(st, inode, inode->i_sb);
-        if (v9ses->cache)
+        if (v9ses->cache == CACHE_LOOSE || v9ses->cache == CACHE_FSCACHE)
                 inode->i_size = i_size;
         spin_unlock(&inode->i_lock);
 out: