在 2020/12/30 6:24, Theodore Ts'o 写道:
On Tue, Dec 29, 2020 at 05:02:08PM +0800, yangerkun wrote:
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(small ext4 img, and consume all space, so the rename with dst
path not exist will fail due to the ENOSPC return from ext4_add_entry in
ext4_rename), the cleanup do drop the nlink for whiteout, but forget to
restore 'ino' with source file. This will lead to "deleted inode
referenced".
Could you sendhave instructions how to reproduce this failure? Many thanks!!
Hi,
Follow step will reproduce it easily!
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/ && 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"
static int ext4_rename(...)
{
...
whiteout = ext4_whiteout_for_rename(&old, credits, &handle);
...
retval = ext4_setent(handle, &old, whiteout->i_ino, EXT4_FT_CHRDEV); //
will replace dir entry with
...
if (!new.bh) {
retval = ext4_add_entry(handle, new.dentry, old.inode); // will fail
with ENOSPC
if (retval)
goto end_rename;
...
end_rename:
...
if (whiteout) { // forget to restore the dir entry's ino
if (retval)
drop_nlink(whiteout);
unlock_new_inode(whiteout);
iput(whiteout);
}
...
}
Thanks,
Kun.
- Ted
.
