From: Luis Henriques <lhenriques@suse.de>
Date: Thu, 12 Nov 2020 15:23:21 +0000
Subject: Revert "ceph: allow rename operation under different quota realms"
Git-commit: 6646ea1c8e8716ab6b8b60ff4930f808442cfe12
Patch-mainline: v5.11-rc1
References: bsc#1180541

This reverts commit dffdcd71458e699e839f0bf47c3d42d64210b939.

When doing a rename across quota realms, there's a corner case that isn't
handled correctly.  Here's a testcase:

  mkdir files limit
  truncate files/file -s 10G
  setfattr limit -n ceph.quota.max_bytes -v 1000000
  mv files limit/

The above will succeed because ftruncate(2) won't immediately notify the
MDSs with the new file size, and thus the quota realms stats won't be
updated.

Since the possible fixes for this issue would have a huge performance impact,
the solution for now is to simply revert to returning -EXDEV when doing a cross
quota realms rename.

URL: https://tracker.ceph.com/issues/48203
Signed-off-by: Luis Henriques <lhenriques@suse.de>
Reviewed-by: Jeff Layton <jlayton@kernel.org>
Reviewed-by: Ilya Dryomov <idryomov@gmail.com>
Signed-off-by: Ilya Dryomov <idryomov@gmail.com>
---
 fs/ceph/dir.c   |    9 +++-----
 fs/ceph/quota.c |   58 --------------------------------------------------------
 fs/ceph/super.h |    3 --
 3 files changed, 6 insertions(+), 64 deletions(-)

--- a/fs/ceph/dir.c
+++ b/fs/ceph/dir.c
@@ -1207,12 +1207,11 @@ static int ceph_rename(struct inode *old
 			op = CEPH_MDS_OP_RENAMESNAP;
 		else
 			return -EROFS;
-	} else if (old_dir != new_dir) {
-		err = ceph_quota_check_rename(mdsc, d_inode(old_dentry),
-					      new_dir);
-		if (err)
-			return err;
 	}
+	/* don't allow cross-quota renames */
+	if ((old_dir != new_dir) &&
+	    (!ceph_quota_is_same_realm(old_dir, new_dir)))
+		return -EXDEV;
 
 	dout("rename dir %p dentry %p to dir %p dentry %p\n",
 	     old_dir, old_dentry, new_dir, new_dentry);
--- a/fs/ceph/quota.c
+++ b/fs/ceph/quota.c
@@ -264,7 +264,7 @@ restart:
 	return NULL;
 }
 
-static bool ceph_quota_is_same_realm(struct inode *old, struct inode *new)
+bool ceph_quota_is_same_realm(struct inode *old, struct inode *new)
 {
 	struct ceph_mds_client *mdsc = ceph_inode_to_client(old)->mdsc;
 	struct ceph_snap_realm *old_realm, *new_realm;
@@ -516,59 +516,3 @@ bool ceph_quota_update_statfs(struct cep
 	return is_updated;
 }
 
-/*
- * ceph_quota_check_rename - check if a rename can be executed
- * @mdsc:	MDS client instance
- * @old:	inode to be copied
- * @new:	destination inode (directory)
- *
- * This function verifies if a rename (e.g. moving a file or directory) can be
- * executed.  It forces an rstat update in the @new target directory (and in the
- * source @old as well, if it's a directory).  The actual check is done both for
- * max_files and max_bytes.
- *
- * This function returns 0 if it's OK to do the rename, or, if quotas are
- * exceeded, -EXDEV (if @old is a directory) or -EDQUOT.
- */
-int ceph_quota_check_rename(struct ceph_mds_client *mdsc,
-			    struct inode *old, struct inode *new)
-{
-	struct ceph_inode_info *ci_old = ceph_inode(old);
-	int ret = 0;
-
-	if (ceph_quota_is_same_realm(old, new))
-		return 0;
-
-	/*
-	 * Get the latest rstat for target directory (and for source, if a
-	 * directory)
-	 */
-	ret = ceph_do_getattr(new, CEPH_STAT_RSTAT, false);
-	if (ret)
-		return ret;
-
-	if (S_ISDIR(old->i_mode)) {
-		ret = ceph_do_getattr(old, CEPH_STAT_RSTAT, false);
-		if (ret)
-			return ret;
-		ret = check_quota_exceeded(new, QUOTA_CHECK_MAX_BYTES_OP,
-					   ci_old->i_rbytes);
-		if (!ret)
-			ret = check_quota_exceeded(new,
-						   QUOTA_CHECK_MAX_FILES_OP,
-						   ci_old->i_rfiles +
-						   ci_old->i_rsubdirs);
-		if (ret)
-			ret = -EXDEV;
-	} else {
-		ret = check_quota_exceeded(new, QUOTA_CHECK_MAX_BYTES_OP,
-					   i_size_read(old));
-		if (!ret)
-			ret = check_quota_exceeded(new,
-						   QUOTA_CHECK_MAX_FILES_OP, 1);
-		if (ret)
-			ret = -EDQUOT;
-	}
-
-	return ret;
-}
--- a/fs/ceph/super.h
+++ b/fs/ceph/super.h
@@ -1209,14 +1209,13 @@ extern void ceph_handle_quota(struct cep
 			      struct ceph_mds_session *session,
 			      struct ceph_msg *msg);
 extern bool ceph_quota_is_max_files_exceeded(struct inode *inode);
+extern bool ceph_quota_is_same_realm(struct inode *old, struct inode *new);
 extern bool ceph_quota_is_max_bytes_exceeded(struct inode *inode,
 					     loff_t newlen);
 extern bool ceph_quota_is_max_bytes_approaching(struct inode *inode,
 						loff_t newlen);
 extern bool ceph_quota_update_statfs(struct ceph_fs_client *fsc,
 				     struct kstatfs *buf);
-extern int ceph_quota_check_rename(struct ceph_mds_client *mdsc,
-				   struct inode *old, struct inode *new);
 extern void ceph_cleanup_quotarealms_inodes(struct ceph_mds_client *mdsc);
 
 #endif /* _FS_CEPH_SUPER_H */