fs/9p: Prevent parallel rename when doing fid_lookup
During fid lookup we need to make sure that the dentry->d_parent doesn't
change so that we can safely walk the parent dentries. To ensure that
we need to prevent cross directory rename during fid_lookup. Add a
per superblock rename_sem rw_semaphore to prevent parallel fid lookup and
rename.
Signed-off-by: Aneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com>
Signed-off-by: Venkateswararao Jujjuri <jvrao@linux.vnet.ibm.com>
Signed-off-by: Eric Van Hensbergen <ericvh@gmail.com>
diff --git a/fs/9p/vfs_inode.c b/fs/9p/vfs_inode.c
index 39352ef..75c261f 100644
--- a/fs/9p/vfs_inode.c
+++ b/fs/9p/vfs_inode.c
@@ -948,6 +948,7 @@
sb = dir->i_sb;
v9ses = v9fs_inode2v9ses(dir);
+ /* We can walk d_parent because we hold the dir->i_mutex */
dfid = v9fs_fid_lookup(dentry->d_parent);
if (IS_ERR(dfid))
return ERR_CAST(dfid);
@@ -1055,27 +1056,33 @@
goto clunk_olddir;
}
+ down_write(&v9ses->rename_sem);
if (v9fs_proto_dotl(v9ses)) {
retval = p9_client_rename(oldfid, newdirfid,
(char *) new_dentry->d_name.name);
if (retval != -ENOSYS)
goto clunk_newdir;
}
+ if (old_dentry->d_parent != new_dentry->d_parent) {
+ /*
+ * 9P .u can only handle file rename in the same directory
+ */
- /* 9P can only handle file rename in the same directory */
- if (memcmp(&olddirfid->qid, &newdirfid->qid, sizeof(newdirfid->qid))) {
P9_DPRINTK(P9_DEBUG_ERROR,
"old dir and new dir are different\n");
retval = -EXDEV;
goto clunk_newdir;
}
-
v9fs_blank_wstat(&wstat);
wstat.muid = v9ses->uname;
wstat.name = (char *) new_dentry->d_name.name;
retval = p9_client_wstat(oldfid, &wstat);
clunk_newdir:
+ if (!retval)
+ /* successful rename */
+ d_move(old_dentry, new_dentry);
+ up_write(&v9ses->rename_sem);
p9_client_clunk(newdirfid);
clunk_olddir: