[Devel] [PATCH RH7 2/2] ext4: fix bug for rename with RENAME_WHITEOUT

[Kirill Tkhai]

From: yangerkun <yangerkun at huawei.com>

ms commit 6b4b8e6b4ad8

We got a "deleted inode referenced" warning cross our fsstress test. The
bug can be reproduced easily with following steps:

cd /dev/shm
mkdir test/
fallocate -l 128M img
mkfs.ext4 -b 1024 img
mount img test/
dd if=/dev/zero of=test/foo bs=1M count=128
mkdir test/dir/ && cd test/dir/
for ((i=0;i<1000;i++)); do touch file$i; done # consume all block
cd ~ && renameat2(AT_FDCWD, /dev/shm/test/dir/file1, AT_FDCWD,
/dev/shm/test/dir/dst_file, RENAME_WHITEOUT) # ext4_add_entry in
ext4_rename will return ENOSPC!!
cd /dev/shm/ && umount test/ && mount img test/ && ls -li test/dir/file1
We will get the output:
"ls: cannot access 'test/dir/file1': Structure needs cleaning"
and the dmesg show:
"EXT4-fs error (device loop0): ext4_lookup:1626: inode #2049: comm ls:
deleted inode referenced: 139"

ext4_rename will create a special inode for whiteout and use this 'ino'
to replace the source file's dir entry 'ino'. Once error happens
latter(the error above was the ENOSPC return from ext4_add_entry in
ext4_rename since all space has been consumed), the cleanup do drop the
nlink for whiteout, but forget to restore 'ino' with source file. This
will trigger the bug describle as above.

Signed-off-by: yangerkun <yangerkun at huawei.com>
Reviewed-by: Jan Kara <jack at suse.cz>
Cc: stable at vger.kernel.org
Fixes: cd808deced43 ("ext4: support RENAME_WHITEOUT")
Link: https://lore.kernel.org/r/20210105062857.3566-1-yangerkun@huawei.com
Signed-off-by: Theodore Ts'o <tytso at mit.edu>
Signed-off-by: Kirill Tkhai <ktkhai at virtuozzo.com>
---
 fs/ext4/namei.c |    9 +++++----
 1 file changed, 5 insertions(+), 4 deletions(-)

diff --git a/fs/ext4/namei.c b/fs/ext4/namei.c
index e2dea0b7b5a7..5279a83f4040 100644
--- a/fs/ext4/namei.c
+++ b/fs/ext4/namei.c
@@ -3155,8 +3155,6 @@ static int ext4_setent(handle_t *handle, struct ext4_renament *ent,
 			return retval2;
 		}
 	}
-	brelse(ent->bh);
-	ent->bh = NULL;
 
 	return retval;
 }
@@ -3344,6 +3342,7 @@ static int ext4_rename(struct inode *old_dir, struct dentry *old_dentry,
 		}
 	}
 
+	old_file_type = old.de->file_type;
 	if (IS_DIRSYNC(old.dir) || IS_DIRSYNC(new.dir))
 		ext4_handle_sync(handle);
 
@@ -3371,7 +3370,6 @@ static int ext4_rename(struct inode *old_dir, struct dentry *old_dentry,
 	force_reread = (new.dir->i_ino == old.dir->i_ino &&
 			ext4_test_inode_flag(new.dir, EXT4_INODE_INLINE_DATA));
 
-	old_file_type = old.de->file_type;
 	if (whiteout) {
 		/*
 		 * Do this before adding a new entry, so the old entry is sure
@@ -3453,8 +3451,11 @@ static int ext4_rename(struct inode *old_dir, struct dentry *old_dentry,
 
 end_rename:
 	if (whiteout) {
-		if (retval)
+		if (retval) {
+			ext4_setent(handle, &old,
+				old.inode->i_ino, old_file_type);
 			drop_nlink(whiteout);
+		}
 		unlock_new_inode(whiteout);
 		iput(whiteout);
 	}