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/v9fs.h b/fs/9p/v9fs.h
index bd8496d..89657e8 100644
--- a/fs/9p/v9fs.h
+++ b/fs/9p/v9fs.h
@@ -130,6 +130,7 @@
#endif
unsigned int cache_validity;
struct p9_fid *writeback_fid;
+ struct mutex v_mutex;
struct inode vfs_inode;
};
diff --git a/fs/9p/vfs_file.c b/fs/9p/vfs_file.c
index 78bcb97..3337d58 100644
--- a/fs/9p/vfs_file.c
+++ b/fs/9p/vfs_file.c
@@ -90,6 +90,7 @@
}
file->private_data = fid;
+ mutex_lock(&v9inode->v_mutex);
if (v9ses->cache && !v9inode->writeback_fid) {
/*
* clone a fid and add it to writeback_fid
@@ -101,10 +102,12 @@
fid = v9fs_writeback_fid(file->f_path.dentry);
if (IS_ERR(fid)) {
err = PTR_ERR(fid);
+ mutex_unlock(&v9inode->v_mutex);
goto out_error;
}
v9inode->writeback_fid = (void *) fid;
}
+ mutex_unlock(&v9inode->v_mutex);
#ifdef CONFIG_9P_FSCACHE
if (v9ses->cache)
v9fs_cache_inode_set_cookie(inode, file);
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);
diff --git a/fs/9p/vfs_inode_dotl.c b/fs/9p/vfs_inode_dotl.c
index 67c138e..327c578 100644
--- a/fs/9p/vfs_inode_dotl.c
+++ b/fs/9p/vfs_inode_dotl.c
@@ -245,6 +245,7 @@
v9fs_set_create_acl(dentry, dacl, pacl);
v9inode = V9FS_I(inode);
+ mutex_lock(&v9inode->v_mutex);
if (v9ses->cache && !v9inode->writeback_fid) {
/*
* clone a fid and add it to writeback_fid
@@ -256,10 +257,12 @@
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);
/* Since we are opening a file, assign the open fid to the file */
filp = lookup_instantiate_filp(nd, dentry, generic_file_open);
if (IS_ERR(filp)) {