dquot: move dquot initialization responsibility into the filesystem

Currently various places in the VFS call vfs_dq_init directly.  This means
we tie the quota code into the VFS.  Get rid of that and make the
filesystem responsible for the initialization.   For most metadata operations
this is a straight forward move into the methods, but for truncate and
open it's a bit more complicated.

For truncate we currently only call vfs_dq_init for the sys_truncate case
because open already takes care of it for ftruncate and open(O_TRUNC) - the
new code causes an additional vfs_dq_init for those which is harmless.

For open the initialization is moved from do_filp_open into the open method,
which means it happens slightly earlier now, and only for regular files.
The latter is fine because we don't need to initialize it for operations
on special files, and we already do it as part of the namespace operations
for directories.

Add a dquot_file_open helper that filesystems that support generic quotas
can use to fill in ->open.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Jan Kara <jack@suse.cz>

1 files changed, 14 insertions, 0 deletions

diff --git a/fs/quota/dquot.c b/fs/quota/dquot.c
index cd83c5b..6244bca 100644
--- a/fs/quota/dquot.c
+++ b/fs/quota/dquot.c
@@ -1821,6 +1821,20 @@ const struct dquot_operations dquot_operations = {
 };
 
 /*
+ * Generic helper for ->open on filesystems supporting disk quotas.
+ */
+int dquot_file_open(struct inode *inode, struct file *file)
+{
+	int error;
+
+	error = generic_file_open(inode, file);
+	if (!error && (file->f_mode & FMODE_WRITE))
+		vfs_dq_init(inode);
+	return error;
+}
+EXPORT_SYMBOL(dquot_file_open);
+
+/*
  * Turn quota off on a device. type == -1 ==> quotaoff for all types (umount)
  */
 int vfs_quota_disable(struct super_block *sb, int type, unsigned int flags)