[PATCH] fuse: add bmap support

Add support for the BMAP operation for block device based filesystems.  This
is needed to support swap-files and lilo.

Signed-off-by: Miklos Szeredi <miklos@szeredi.hu>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>

1 files changed, 37 insertions, 0 deletions

diff --git a/fs/fuse/file.c b/fs/fuse/file.c
index 763a50daf1c0..128f79c40803 100644
--- a/fs/fuse/file.c
+++ b/fs/fuse/file.c
@@ -754,6 +754,42 @@ static int fuse_file_lock(struct file *file, int cmd, struct file_lock *fl)
         return err;
 }
 
+static sector_t fuse_bmap(struct address_space *mapping, sector_t block)
+{
+        struct inode *inode = mapping->host;
+        struct fuse_conn *fc = get_fuse_conn(inode);
+        struct fuse_req *req;
+        struct fuse_bmap_in inarg;
+        struct fuse_bmap_out outarg;
+        int err;
+
+        if (!inode->i_sb->s_bdev || fc->no_bmap)
+                return 0;
+
+        req = fuse_get_req(fc);
+        if (IS_ERR(req))
+                return 0;
+
+        memset(&inarg, 0, sizeof(inarg));
+        inarg.block = block;
+        inarg.blocksize = inode->i_sb->s_blocksize;
+        req->in.h.opcode = FUSE_BMAP;
+        req->in.h.nodeid = get_node_id(inode);
+        req->in.numargs = 1;
+        req->in.args[0].size = sizeof(inarg);
+        req->in.args[0].value = &inarg;
+        req->out.numargs = 1;
+        req->out.args[0].size = sizeof(outarg);
+        req->out.args[0].value = &outarg;
+        request_send(fc, req);
+        err = req->out.h.error;
+        fuse_put_request(fc, req);
+        if (err == -ENOSYS)
+                fc->no_bmap = 1;
+
+        return err ? 0 : outarg.block;
+}
+
 static const struct file_operations fuse_file_operations = {
         .llseek         = generic_file_llseek,
         .read           = do_sync_read,
@@ -787,6 +823,7 @@ static const struct address_space_operations fuse_file_aops  = {
         .commit_write   = fuse_commit_write,
         .readpages      = fuse_readpages,
         .set_page_dirty = fuse_set_page_dirty,
+        .bmap           = fuse_bmap,
 };
 
 void fuse_init_file_inode(struct inode *inode)