[v7,2/7] kernfs: do not alloc iattrs in kernfs_xattr_get

Commit Message

Ondrej Mosnacek Feb. 22, 2019, 2:57 p.m. UTC

This is a read-only operation, so we can simply return -ENODATA if
kn->iattr is NULL.

Signed-off-by: Ondrej Mosnacek <[e-mail]>
---
 fs/kernfs/inode.c | 18 ++++++++++++++----
 1 file changed, 14 insertions(+), 4 deletions(-)

Patch

diff --git a/fs/kernfs/inode.c b/fs/kernfs/inode.c
index ffd1ef962728..7a7985961bbf 100644
--- a/fs/kernfs/inode.c
+++ b/fs/kernfs/inode.c
@@ -31,14 +31,14 @@  static const struct inode_operations kernfs_iops = {
 	.listxattr	= kernfs_iop_listxattr,
 };
 
-static struct kernfs_iattrs *kernfs_iattrs(struct kernfs_node *kn)
+static struct kernfs_iattrs *__kernfs_iattrs(struct kernfs_node *kn, int alloc)
 {
 	static DEFINE_MUTEX(iattr_mutex);
 	struct kernfs_iattrs *ret;
 
 	mutex_lock(&iattr_mutex);
 
-	if (kn->iattr)
+	if (kn->iattr || !alloc)
 		goto out_unlock;
 
 	kn->iattr = kzalloc(sizeof(struct kernfs_iattrs), GFP_KERNEL);
@@ -60,6 +60,16 @@  out_unlock:
 	return ret;
 }
 
+static struct kernfs_iattrs *kernfs_iattrs(struct kernfs_node *kn)
+{
+	return __kernfs_iattrs(kn, 1);
+}
+
+static struct kernfs_iattrs *kernfs_iattrs_noalloc(struct kernfs_node *kn)
+{
+	return __kernfs_iattrs(kn, 0);
+}
+
 int __kernfs_setattr(struct kernfs_node *kn, const struct iattr *iattr)
 {
 	struct kernfs_iattrs *attrs;
@@ -306,9 +316,9 @@  static int kernfs_xattr_get(const struct xattr_handler *handler,
 	struct kernfs_node *kn = inode->i_private;
 	struct kernfs_iattrs *attrs;
 
-	attrs = kernfs_iattrs(kn);
+	attrs = kernfs_iattrs_noalloc(kn);
 	if (!attrs)
-		return -ENOMEM;
+		return -ENODATA;
 
 	return simple_xattr_get(&attrs->xattrs, name, value, size);
 }