gfs2: Change inode qa_data to allow multiple users

Before this patch, multiple users called gfs2_qa_alloc which allocated
a qadata structure to the inode, if quotas are turned on. Later, in
file close or evict, the structure was deleted with gfs2_qa_delete.
But there can be several competing processes who need access to the
structure. There were races between file close (release) and the others.
Thus, a release could delete the structure out from under a process
that relied upon its existence. For example, chown.

This patch changes the management of the qadata structures to be
a get/put scheme. Function gfs2_qa_alloc has been changed to gfs2_qa_get
and if the structure is allocated, the count essentially starts out at
1. Function gfs2_qa_delete has been renamed to gfs2_qa_put, and the
last guy to decrement the count to 0 frees the memory.

Signed-off-by: Bob Peterson <rpeterso@redhat.com>

1 files changed, 19 insertions, 13 deletions

diff --git a/fs/gfs2/inode.c b/fs/gfs2/inode.c
index 710f1c644f87..d1a24753c55f 100644
--- a/fs/gfs2/inode.c
+++ b/fs/gfs2/inode.c
@@ -588,13 +588,13 @@ static int gfs2_create_inode(struct inode *dir, struct dentry *dentry,
 	if (!name->len || name->len > GFS2_FNAMESIZE)
 		return -ENAMETOOLONG;
 
-	error = gfs2_qa_alloc(dip);
+	error = gfs2_qa_get(dip);
 	if (error)
 		return error;
 
 	error = gfs2_rindex_update(sdp);
 	if (error)
-		return error;
+		goto fail;
 
 	error = gfs2_glock_nq_init(dip->i_gl, LM_ST_EXCLUSIVE, 0, ghs);
 	if (error)
@@ -641,7 +641,7 @@ static int gfs2_create_inode(struct inode *dir, struct dentry *dentry,
 		goto fail_gunlock;
 
 	ip = GFS2_I(inode);
-	error = gfs2_qa_alloc(ip);
+	error = gfs2_qa_get(ip);
 	if (error)
 		goto fail_free_acls;
 
@@ -776,6 +776,7 @@ fail_gunlock2:
 	clear_bit(GLF_INODE_CREATING, &io_gl->gl_flags);
 	gfs2_glock_put(io_gl);
 fail_free_inode:
+	gfs2_qa_put(ip);
 	if (ip->i_gl) {
 		glock_clear_object(ip->i_gl, ip);
 		gfs2_glock_put(ip->i_gl);
@@ -798,6 +799,7 @@ fail_gunlock:
 	if (gfs2_holder_initialized(ghs + 1))
 		gfs2_glock_dq_uninit(ghs + 1);
 fail:
+	gfs2_qa_put(dip);
 	return error;
 }
 
@@ -899,7 +901,7 @@ static int gfs2_link(struct dentry *old_dentry, struct inode *dir,
 	if (S_ISDIR(inode->i_mode))
 		return -EPERM;
 
-	error = gfs2_qa_alloc(dip);
+	error = gfs2_qa_get(dip);
 	if (error)
 		return error;
 
@@ -1002,6 +1004,7 @@ out_gunlock:
 out_child:
 	gfs2_glock_dq(ghs);
 out_parent:
+	gfs2_qa_put(ip);
 	gfs2_holder_uninit(ghs);
 	gfs2_holder_uninit(ghs + 1);
 	return error;
@@ -1362,7 +1365,7 @@ static int gfs2_rename(struct inode *odir, struct dentry *odentry,
 	if (error)
 		return error;
 
-	error = gfs2_qa_alloc(ndip);
+	error = gfs2_qa_get(ndip);
 	if (error)
 		return error;
 
@@ -1562,6 +1565,7 @@ out_gunlock_r:
 	if (gfs2_holder_initialized(&r_gh))
 		gfs2_glock_dq_uninit(&r_gh);
 out:
+	gfs2_qa_put(ndip);
 	return error;
 }
 
@@ -1873,10 +1877,9 @@ static int setattr_chown(struct inode *inode, struct iattr *attr)
 		ouid = nuid = NO_UID_QUOTA_CHANGE;
 	if (!(attr->ia_valid & ATTR_GID) || gid_eq(ogid, ngid))
 		ogid = ngid = NO_GID_QUOTA_CHANGE;
-
-	error = gfs2_qa_alloc(ip);
+	error = gfs2_qa_get(ip);
 	if (error)
-		goto out;
+		return error;
 
 	error = gfs2_rindex_update(sdp);
 	if (error)
@@ -1914,6 +1917,7 @@ out_end_trans:
 out_gunlock_q:
 	gfs2_quota_unlock(ip);
 out:
+	gfs2_qa_put(ip);
 	return error;
 }
 
@@ -1935,21 +1939,21 @@ static int gfs2_setattr(struct dentry *dentry, struct iattr *attr)
 	struct gfs2_holder i_gh;
 	int error;
 
-	error = gfs2_qa_alloc(ip);
+	error = gfs2_qa_get(ip);
 	if (error)
 		return error;
 
 	error = gfs2_glock_nq_init(ip->i_gl, LM_ST_EXCLUSIVE, 0, &i_gh);
 	if (error)
-		return error;
+		goto out;
 
 	error = -EPERM;
 	if (IS_IMMUTABLE(inode) || IS_APPEND(inode))
-		goto out;
+		goto error;
 
 	error = setattr_prepare(dentry, attr);
 	if (error)
-		goto out;
+		goto error;
 
 	if (attr->ia_valid & ATTR_SIZE)
 		error = gfs2_setattr_size(inode, attr->ia_size);
@@ -1961,10 +1965,12 @@ static int gfs2_setattr(struct dentry *dentry, struct iattr *attr)
 			error = posix_acl_chmod(inode, inode->i_mode);
 	}
 
-out:
+error:
 	if (!error)
 		mark_inode_dirty(inode);
 	gfs2_glock_dq_uninit(&i_gh);
+out:
+	gfs2_qa_put(ip);
 	return error;
 }