On Fri, Jun 22, 2018 at 12:15 AM, <gregkh@xxxxxxxxxxxxxxxxxxx> wrote:
>
> The patch below does not apply to the 4.17-stable tree.
There is a [backport hint] at the end of the commit message.
Need to take the 2 prep commits.
Same for all stable branches.
Cheers,
Amir.
> If someone wants it applied there, or to any other stable or longterm
> tree, then please email the backport, including the original git commit
> id to <stable@xxxxxxxxxxxxxxx>.
>
> thanks,
>
> greg k-h
>
> ------------------ original commit in Linus's tree ------------------
>
> From db6516a5e7ddb6dc72d167b920f2f272596ea22d Mon Sep 17 00:00:00 2001
> From: Amir Goldstein <amir73il@xxxxxxxxx>
> Date: Sun, 13 May 2018 22:54:44 -0400
> Subject: [PATCH] ext4: do not update s_last_mounted of a frozen fs
>
> If fs is frozen after mount and before the first file open, the
> update of s_last_mounted bypasses freeze protection and prints out
> a WARNING splat:
>
> $ mount /vdf
> $ fsfreeze -f /vdf
> $ cat /vdf/foo
>
> [ 31.578555] WARNING: CPU: 1 PID: 1415 at
> fs/ext4/ext4_jbd2.c:53 ext4_journal_check_start+0x48/0x82
>
> [ 31.614016] Call Trace:
> [ 31.614997] __ext4_journal_start_sb+0xe4/0x1a4
> [ 31.616771] ? ext4_file_open+0xb6/0x189
> [ 31.618094] ext4_file_open+0xb6/0x189
>
> If fs is frozen, skip s_last_mounted update.
>
> [backport hint: to apply to stable tree, need to apply also patches
> vfs: add the sb_start_intwrite_trylock() helper
> ext4: factor out helper ext4_sample_last_mounted()]
>
> Cc: stable@xxxxxxxxxxxxxxx
> Fixes: bc0b0d6d69ee ("ext4: update the s_last_mounted field in the superblock")
> Signed-off-by: Amir Goldstein <amir73il@xxxxxxxxx>
> Signed-off-by: Theodore Ts'o <tytso@xxxxxxx>
> Reviewed-by: Jan Kara <jack@xxxxxxx>
>
> diff --git a/fs/ext4/file.c b/fs/ext4/file.c
> index c48ea76b63e4..7f8023340eb8 100644
> --- a/fs/ext4/file.c
> +++ b/fs/ext4/file.c
> @@ -393,7 +393,7 @@ static int ext4_sample_last_mounted(struct super_block *sb,
> if (likely(sbi->s_mount_flags & EXT4_MF_MNTDIR_SAMPLED))
> return 0;
>
> - if (sb_rdonly(sb))
> + if (sb_rdonly(sb) || !sb_start_intwrite_trylock(sb))
> return 0;
>
> sbi->s_mount_flags |= EXT4_MF_MNTDIR_SAMPLED;
> @@ -407,21 +407,25 @@ static int ext4_sample_last_mounted(struct super_block *sb,
> path.mnt = mnt;
> path.dentry = mnt->mnt_root;
> cp = d_path(&path, buf, sizeof(buf));
> + err = 0;
> if (IS_ERR(cp))
> - return 0;
> + goto out;
>
> handle = ext4_journal_start_sb(sb, EXT4_HT_MISC, 1);
> + err = PTR_ERR(handle);
> if (IS_ERR(handle))
> - return PTR_ERR(handle);
> + goto out;
> BUFFER_TRACE(sbi->s_sbh, "get_write_access");
> err = ext4_journal_get_write_access(handle, sbi->s_sbh);
> if (err)
> - goto out;
> + goto out_journal;
> strlcpy(sbi->s_es->s_last_mounted, cp,
> sizeof(sbi->s_es->s_last_mounted));
> ext4_handle_dirty_super(handle, sb);
> -out:
> +out_journal:
> ext4_journal_stop(handle);
> +out:
> + sb_end_intwrite(sb);
> return err;
> }
>
>
