Re: FAILED: patch "[PATCH] ext4: do not update s_last_mounted of a frozen fs" failed to apply to 4.17-stable tree

On Fri, Jun 22, 2018 at 12:15 AM, gregkh@linuxfoundation.org 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@vger.kernel.org.

thanks,

greg k-h

------------------ original commit in Linus's tree ------------------

From db6516a5e7ddb6dc72d167b920f2f272596ea22d Mon Sep 17 00:00:00 2001 From: Amir Goldstein amir73il@gmail.com 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@vger.kernel.org Fixes: bc0b0d6d69ee ("ext4: update the s_last_mounted field in the superblock") Signed-off-by: Amir Goldstein amir73il@gmail.com Signed-off-by: Theodore Ts'o tytso@mit.edu Reviewed-by: Jan Kara jack@suse.cz

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;
  

}