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Commit 5a7e0a8c authored by Aneesh Kumar K.V's avatar Aneesh Kumar K.V Committed by Eric Van Hensbergen
Browse files

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: default avatarAneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com>
Signed-off-by: default avatarVenkateswararao Jujjuri <jvrao@linux.vnet.ibm.com>
Signed-off-by: default avatarEric Van Hensbergen <ericvh@gmail.com>
parent f741a79e

fs/9p/v9fs.h

+1 −0
Original line number Diff line number Diff line
@@ -130,6 +130,7 @@ struct v9fs_inode { 
#endif

	unsigned int cache_validity;

	struct p9_fid *writeback_fid;

	struct mutex v_mutex;

	struct inode vfs_inode;

};

fs/9p/vfs_file.c

+3 −0
Original line number Diff line number Diff line
@@ -90,6 +90,7 @@ int v9fs_file_open(struct inode *inode, struct file *file) 
	}



	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 @@ int v9fs_file_open(struct inode *inode, struct file *file) 
		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);

fs/9p/vfs_inode.c

+4 −0
Original line number Diff line number Diff line
@@ -221,6 +221,7 @@ struct inode *v9fs_alloc_inode(struct super_block *sb) 
#endif

	v9inode->writeback_fid = NULL;

	v9inode->cache_validity = 0;

	mutex_init(&v9inode->v_mutex);

	return &v9inode->vfs_inode;

}
@@ -650,6 +651,7 @@ v9fs_vfs_create(struct inode *dir, struct dentry *dentry, int mode, 
	/* 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 @@ v9fs_vfs_create(struct inode *dir, struct dentry *dentry, int mode, 
			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);

fs/9p/vfs_inode_dotl.c

+3 −0
Original line number Diff line number Diff line
@@ -245,6 +245,7 @@ v9fs_vfs_create_dotl(struct inode *dir, struct dentry *dentry, int omode, 
	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 @@ v9fs_vfs_create_dotl(struct inode *dir, struct dentry *dentry, int omode, 
		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)) {