9p: Define and implement TLINK for 9P2000.L

This patch adds a helper function to get the dentry from inode and
uses it in creating a Hardlink

SYNOPSIS

size[4] Tlink tag[2] dfid[4] oldfid[4] newpath[s]

size[4] Rlink tag[2]

DESCRIPTION

Create a link 'newpath' in directory pointed by dfid linking to oldfid path.

[sripathik@in.ibm.com : p9_client_link should not free req structure
if p9_client_rpc has returned an error.]

Signed-off-by: Venkateswararao Jujjuri <jvrao@linux.vnet.ibm.com>
Signed-off-by: Eric Van Hensbergen <ericvh@gmail.com>

1 files changed, 106 insertions, 1 deletions

diff --git a/fs/9p/vfs_inode.c b/fs/9p/vfs_inode.c
index a90324f4546a..e6ece237241f 100644
--- a/fs/9p/vfs_inode.c
+++ b/fs/9p/vfs_inode.c
@@ -236,6 +236,41 @@ void v9fs_destroy_inode(struct inode *inode)
 #endif
 
 /**
+ * v9fs_get_fsgid_for_create - Helper function to get the gid for creating a
+ * new file system object. This checks the S_ISGID to determine the owning
+ * group of the new file system object.
+ */
+
+static gid_t v9fs_get_fsgid_for_create(struct inode *dir_inode)
+{
+        BUG_ON(dir_inode == NULL);
+
+        if (dir_inode->i_mode & S_ISGID) {
+                /* set_gid bit is set.*/
+                return dir_inode->i_gid;
+        }
+        return current_fsgid();
+}
+
+/**
+ * v9fs_dentry_from_dir_inode - helper function to get the dentry from
+ * dir inode.
+ *
+ */
+
+struct dentry *v9fs_dentry_from_dir_inode(struct inode *inode)
+{
+        struct dentry *dentry;
+
+        spin_lock(&dcache_lock);
+        /* Directory should have only one entry. */
+        BUG_ON(S_ISDIR(inode->i_mode) && !list_is_singular(&inode->i_dentry));
+        dentry = list_entry(inode->i_dentry.next, struct dentry, d_alias);
+        spin_unlock(&dcache_lock);
+        return dentry;
+}
+
+/**
  * v9fs_get_inode - helper function to setup an inode
  * @sb: superblock
  * @mode: mode to setup inode with
@@ -1374,6 +1409,76 @@ clunk_fid:
 }
 
 /**
+ * v9fs_vfs_link_dotl - create a hardlink for dotl
+ * @old_dentry: dentry for file to link to
+ * @dir: inode destination for new link
+ * @dentry: dentry for link
+ *
+ */
+
+static int
+v9fs_vfs_link_dotl(struct dentry *old_dentry, struct inode *dir,
+                struct dentry *dentry)
+{
+        int err;
+        struct p9_fid *dfid, *oldfid;
+        char *name;
+        struct v9fs_session_info *v9ses;
+        struct dentry *dir_dentry;
+
+        P9_DPRINTK(P9_DEBUG_VFS, "dir ino: %lu, old_name: %s, new_name: %s\n",
+                        dir->i_ino, old_dentry->d_name.name,
+                        dentry->d_name.name);
+
+        v9ses = v9fs_inode2v9ses(dir);
+        dir_dentry = v9fs_dentry_from_dir_inode(dir);
+        dfid = v9fs_fid_lookup(dir_dentry);
+        if (IS_ERR(dfid))
+                return PTR_ERR(dfid);
+
+        oldfid = v9fs_fid_lookup(old_dentry);
+        if (IS_ERR(oldfid))
+                return PTR_ERR(oldfid);
+
+        name = (char *) dentry->d_name.name;
+
+        err = p9_client_link(dfid, oldfid, (char *)dentry->d_name.name);
+
+        if (err < 0) {
+                P9_DPRINTK(P9_DEBUG_VFS, "p9_client_link failed %d\n", err);
+                return err;
+        }
+
+        if (v9ses->cache == CACHE_LOOSE || v9ses->cache == CACHE_FSCACHE) {
+                /* Get the latest stat info from server. */
+                struct p9_fid *fid;
+                struct p9_stat_dotl *st;
+
+                fid = v9fs_fid_lookup(old_dentry);
+                if (IS_ERR(fid))
+                        return PTR_ERR(fid);
+
+                st = p9_client_getattr_dotl(fid, P9_STATS_BASIC);
+                if (IS_ERR(st))
+                        return PTR_ERR(st);
+
+                v9fs_stat2inode_dotl(st, old_dentry->d_inode);
+
+                kfree(st);
+        } else {
+                /* Caching disabled. No need to get upto date stat info.
+                 * This dentry will be released immediately. So, just i_count++
+                 */
+                atomic_inc(&old_dentry->d_inode->i_count);
+        }
+
+        dentry->d_op = old_dentry->d_op;
+        d_instantiate(dentry, old_dentry->d_inode);
+
+        return err;
+}
+
+/**
  * v9fs_vfs_mknod - create a special file
  * @dir: inode destination for new link
  * @dentry: dentry for file
@@ -1422,7 +1527,7 @@ static const struct inode_operations v9fs_dir_inode_operations_dotu = {
         .create = v9fs_vfs_create,
         .lookup = v9fs_vfs_lookup,
         .symlink = v9fs_vfs_symlink,
-        .link = v9fs_vfs_link,
+        .link = v9fs_vfs_link_dotl,
         .unlink = v9fs_vfs_unlink,
         .mkdir = v9fs_vfs_mkdir,
         .rmdir = v9fs_vfs_rmdir,