fs/9p: Fix race in initializing writeback fid
When two process open the same file we can end up with both of them
allocating the writeback_fid. Add a new mutex which can be used
for synchronizing v9fs_inode member values.
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 8a2c232..c6cef24 100644
--- a/fs/9p/vfs_inode.c
+++ b/fs/9p/vfs_inode.c
@@ -221,6 +221,7 @@
#endif
v9inode->writeback_fid = NULL;
v9inode->cache_validity = 0;
+ mutex_init(&v9inode->v_mutex);
return &v9inode->vfs_inode;
}
@@ -650,6 +651,7 @@
/* if we are opening a file, assign the open fid to the file */
if (nd && nd->flags & LOOKUP_OPEN) {
v9inode = V9FS_I(dentry->d_inode);
+ mutex_lock(&v9inode->v_mutex);
if (v9ses->cache && !v9inode->writeback_fid) {
/*
* clone a fid and add it to writeback_fid
@@ -661,10 +663,12 @@
inode_fid = v9fs_writeback_fid(dentry);
if (IS_ERR(inode_fid)) {
err = PTR_ERR(inode_fid);
+ mutex_unlock(&v9inode->v_mutex);
goto error;
}
v9inode->writeback_fid = (void *) inode_fid;
}
+ mutex_unlock(&v9inode->v_mutex);
filp = lookup_instantiate_filp(nd, dentry, generic_file_open);
if (IS_ERR(filp)) {
err = PTR_ERR(filp);