| From: Amir Goldstein <amir73il@gmail.com> |
| Date: Sun, 13 May 2018 22:54:44 -0400 |
| Subject: ext4: do not update s_last_mounted of a frozen fs |
| |
| commit db6516a5e7ddb6dc72d167b920f2f272596ea22d upstream. |
| |
| 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()] |
| |
| 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> |
| [bwh: Backported to 3.16: adjust context] |
| Signed-off-by: Ben Hutchings <ben@decadent.org.uk> |
| --- |
| fs/ext4/file.c | 14 +++++++++----- |
| 1 file changed, 9 insertions(+), 5 deletions(-) |
| |
| --- a/fs/ext4/file.c |
| +++ b/fs/ext4/file.c |
| @@ -220,7 +220,7 @@ static int ext4_sample_last_mounted(stru |
| if (likely(sbi->s_mount_flags & EXT4_MF_MNTDIR_SAMPLED)) |
| return 0; |
| |
| - if (sb->s_flags & MS_RDONLY) |
| + if (sb->s_flags & MS_RDONLY || !sb_start_intwrite_trylock(sb)) |
| return 0; |
| |
| sbi->s_mount_flags |= EXT4_MF_MNTDIR_SAMPLED; |
| @@ -234,21 +234,25 @@ static int ext4_sample_last_mounted(stru |
| 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; |
| } |
| |