ext4: fix deadlock when converting an inline directory in nojournal mode

In no journal mode, ext4_finish_convert_inline_dir() can self-deadlock
by calling ext4_handle_dirty_dirblock() when it already has taken the
directory lock.  There is a similar self-deadlock in
ext4_incvert_inline_data_nolock() for data files which we'll fix at
the same time.

A simple reproducer demonstrating the problem:

    mke2fs -Fq -t ext2 -O inline_data -b 4k /dev/vdc 64
    mount -t ext4 -o dirsync /dev/vdc /vdc
    cd /vdc
    mkdir file0
    cd file0
    touch file0
    touch file1
    attr -s BurnSpaceInEA -V abcde .
    touch supercalifragilisticexpialidocious

Cc: stable@kernel.org
Link: https://lore.kernel.org/r/20230507021608.1290720-1-tytso@mit.edu
Reported-by: syzbot+91dccab7c64e2850a4e5@syzkaller.appspotmail.com
Link: https://syzkaller.appspot.com/bug?id=ba84cc80a9491d65416bc7877e1650c87530fe8a
Signed-off-by: Theodore Ts'o <tytso@mit.edu>

diff --git a/fs/ext4/inline.c b/fs/ext4/inline.c
index 859bc4e..d3dfc51 100644 (file)
--- a/fs/ext4/inline.c
+++ b/fs/ext4/inline.c
@@ -1175,6 +1175,7 @@ static int ext4_finish_convert_inline_dir(handle_t *handle,
                ext4_initialize_dirent_tail(dir_block,
                                            inode->i_sb->s_blocksize);
        set_buffer_uptodate(dir_block);
+       unlock_buffer(dir_block);
        err = ext4_handle_dirty_dirblock(handle, inode, dir_block);
        if (err)
                return err;
@@ -1249,6 +1250,7 @@ static int ext4_convert_inline_data_nolock(handle_t *handle,
        if (!S_ISDIR(inode->i_mode)) {
                memcpy(data_bh->b_data, buf, inline_size);
                set_buffer_uptodate(data_bh);
+               unlock_buffer(data_bh);
                error = ext4_handle_dirty_metadata(handle,
                                                   inode, data_bh);
        } else {
@@ -1256,7 +1258,6 @@ static int ext4_convert_inline_data_nolock(handle_t *handle,
                                                       buf, inline_size);
        }
 
-       unlock_buffer(data_bh);
 out_restore:
        if (error)
                ext4_restore_inline_data(handle, inode, iloc, buf, inline_size);