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    SubjectRe: hunt for 2.6.37 dm-crypt+ext4 corruption? (was: Re: dm-crypt barrier support is effective)
    On Sun, Dec 12, 2010 at 07:11:28AM -0600, Jon Nelson wrote:
    > I'm glad you've been able to reproduce the problem! If you should need
    > any further assistance, please do not hesitate to ask.

    This patch seems to fix the problem for me. (Unless the partition is
    mounted with mblk_io_submit.)

    Could you confirm that it fixes it for you as well?


    - Ted

    commit a8649d85bd0ab3be6014918bd9eae319a0ffc691
    Author: Theodore Ts'o <>
    Date: Sun Dec 12 20:57:19 2010 -0500

    ext4: Turn off multiple page-io submission by default

    Jon Nelson has found a test case which causes postgresql to fail with
    the error:

    psql:t.sql:4: ERROR: invalid page header in block 38269 of relation base/16384/16581

    Under memory pressure, it looks like part of a file can end up getting
    replaced by zero's. Until we can figure out the cause, we'll roll
    back the change and use block_write_full_page() instead of
    ext4_bio_write_page(). The new, more efficient writing function can
    be used via the mount option mblk_io_submit, so we can test and fix
    the new page I/O code.

    To reproduce the problem, install postgres 8.4 or 9.0, and pin enough
    memory such that the system just at the end of triggering writeback
    before running the following sql script:

    create temporary table foo as select x as a, ARRAY[x] as b FROM
    generate_series(1, 10000000 ) AS x;
    create index foo_a_idx on foo (a);
    create index foo_b_idx on foo USING GIN (b);

    If the temporary table is created on a hard drive partition which is
    encrypted using dm_crypt, then under memory pressure, approximately
    30-40% of the time, pgsql will issue the above failure.

    This patch should fix this problem, and the problem will come back if
    the file system is mounted with the mblk_io_submit mount option.

    Reported-by: Jon Nelson <>
    Signed-off-by: "Theodore Ts'o" <>

    diff --git a/fs/ext4/ext4.h b/fs/ext4/ext4.h
    index 6a5edea..6eb598b 100644
    --- a/fs/ext4/ext4.h
    +++ b/fs/ext4/ext4.h
    @@ -910,6 +910,7 @@ struct ext4_inode_info {
    #define EXT4_MOUNT_JOURNAL_CHECKSUM 0x800000 /* Journal checksums */
    #define EXT4_MOUNT_JOURNAL_ASYNC_COMMIT 0x1000000 /* Journal Async Commit */
    #define EXT4_MOUNT_I_VERSION 0x2000000 /* i_version support */
    +#define EXT4_MOUNT_MBLK_IO_SUBMIT 0x4000000
    #define EXT4_MOUNT_DELALLOC 0x8000000 /* Delalloc support */
    #define EXT4_MOUNT_DATA_ERR_ABORT 0x10000000 /* Abort on file data write */
    #define EXT4_MOUNT_BLOCK_VALIDITY 0x20000000 /* Block validity checking */
    diff --git a/fs/ext4/inode.c b/fs/ext4/inode.c
    index bdbe699..e659597 100644
    --- a/fs/ext4/inode.c
    +++ b/fs/ext4/inode.c
    @@ -2125,9 +2125,12 @@ static int mpage_da_submit_io(struct mpage_da_data *mpd,
    if (unlikely(journal_data && PageChecked(page)))
    err = __ext4_journalled_writepage(page, len);
    - else
    + else if (test_opt(inode->i_sb, MBLK_IO_SUBMIT))
    err = ext4_bio_write_page(&io_submit, page,
    len, mpd->wbc);
    + else
    + err = block_write_full_page(page,
    + noalloc_get_block_write, mpd->wbc);

    if (!err)
    diff --git a/fs/ext4/super.c b/fs/ext4/super.c
    index e32195d..fb15c9c 100644
    --- a/fs/ext4/super.c
    +++ b/fs/ext4/super.c
    @@ -1026,6 +1026,8 @@ static int ext4_show_options(struct seq_file *seq, struct vfsmount *vfs)
    !(def_mount_opts & EXT4_DEFM_NODELALLOC))
    seq_puts(seq, ",nodelalloc");

    + if (test_opt(sb, MBLK_IO_SUBMIT))
    + seq_puts(seq, ",mblk_io_submit");
    if (sbi->s_stripe)
    seq_printf(seq, ",stripe=%lu", sbi->s_stripe);
    @@ -1239,8 +1241,8 @@ enum {
    Opt_jqfmt_vfsold, Opt_jqfmt_vfsv0, Opt_jqfmt_vfsv1, Opt_quota,
    Opt_noquota, Opt_ignore, Opt_barrier, Opt_nobarrier, Opt_err,
    Opt_resize, Opt_usrquota, Opt_grpquota, Opt_i_version,
    - Opt_stripe, Opt_delalloc, Opt_nodelalloc,
    - Opt_block_validity, Opt_noblock_validity,
    + Opt_stripe, Opt_delalloc, Opt_nodelalloc, Opt_mblk_io_submit,
    + Opt_nomblk_io_submit, Opt_block_validity, Opt_noblock_validity,
    Opt_inode_readahead_blks, Opt_journal_ioprio,
    Opt_dioread_nolock, Opt_dioread_lock,
    Opt_discard, Opt_nodiscard,
    @@ -1304,6 +1306,8 @@ static const match_table_t tokens = {
    {Opt_resize, "resize"},
    {Opt_delalloc, "delalloc"},
    {Opt_nodelalloc, "nodelalloc"},
    + {Opt_mblk_io_submit, "mblk_io_submit"},
    + {Opt_nomblk_io_submit, "nomblk_io_submit"},
    {Opt_block_validity, "block_validity"},
    {Opt_noblock_validity, "noblock_validity"},
    {Opt_inode_readahead_blks, "inode_readahead_blks=%u"},
    @@ -1725,6 +1729,12 @@ set_qf_format:
    case Opt_nodelalloc:
    clear_opt(sbi->s_mount_opt, DELALLOC);
    + case Opt_mblk_io_submit:
    + set_opt(sbi->s_mount_opt, MBLK_IO_SUBMIT);
    + break;
    + case Opt_nomblk_io_submit:
    + clear_opt(sbi->s_mount_opt, MBLK_IO_SUBMIT);
    + break;
    case Opt_stripe:
    if (match_int(&args[0], &option))
    return 0;

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