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    Subject[20/40] udf: Fix deadlock when converting file from in-ICB one to normal one
    3.0-stable review patch.  If anyone has any objections, please let me know.

    ------------------

    From: Jan Kara <jack@suse.cz>

    commit d2eb8c359309ec45d6bf5b147303ab8e13be86ea upstream.

    During BKL removal in 2.6.38, conversion of files from in-ICB format to normal
    format got broken. We call ->writepage with i_data_sem held but udf_get_block()
    also acquires i_data_sem thus creating A-A deadlock.

    We fix the problem by dropping i_data_sem before calling ->writepage() which is
    safe since i_mutex still protects us against any changes in the file. Also fix
    pagelock - i_data_sem lock inversion in udf_expand_file_adinicb() by dropping
    i_data_sem before calling find_or_create_page().

    Reported-by: Matthias Matiak <netzpython@mail-on.us>
    Tested-by: Matthias Matiak <netzpython@mail-on.us>
    Reviewed-by: Namjae Jeon <linkinjeon@gmail.com>
    Signed-off-by: Jan Kara <jack@suse.cz>
    Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

    ---
    fs/udf/file.c | 6 +++---
    fs/udf/inode.c | 21 ++++++++++++++++++---
    2 files changed, 21 insertions(+), 6 deletions(-)

    --- a/fs/udf/file.c
    +++ b/fs/udf/file.c
    @@ -125,7 +125,6 @@ static ssize_t udf_file_aio_write(struct
    err = udf_expand_file_adinicb(inode);
    if (err) {
    udf_debug("udf_expand_adinicb: err=%d\n", err);
    - up_write(&iinfo->i_data_sem);
    return err;
    }
    } else {
    @@ -133,9 +132,10 @@ static ssize_t udf_file_aio_write(struct
    iinfo->i_lenAlloc = pos + count;
    else
    iinfo->i_lenAlloc = inode->i_size;
    + up_write(&iinfo->i_data_sem);
    }
    - }
    - up_write(&iinfo->i_data_sem);
    + } else
    + up_write(&iinfo->i_data_sem);

    retval = generic_file_aio_write(iocb, iov, nr_segs, ppos);
    if (retval > 0)
    --- a/fs/udf/inode.c
    +++ b/fs/udf/inode.c
    @@ -145,6 +145,12 @@ const struct address_space_operations ud
    .bmap = udf_bmap,
    };

    +/*
    + * Expand file stored in ICB to a normal one-block-file
    + *
    + * This function requires i_data_sem for writing and releases it.
    + * This function requires i_mutex held
    + */
    int udf_expand_file_adinicb(struct inode *inode)
    {
    struct page *page;
    @@ -163,9 +169,15 @@ int udf_expand_file_adinicb(struct inode
    iinfo->i_alloc_type = ICBTAG_FLAG_AD_LONG;
    /* from now on we have normal address_space methods */
    inode->i_data.a_ops = &udf_aops;
    + up_write(&iinfo->i_data_sem);
    mark_inode_dirty(inode);
    return 0;
    }
    + /*
    + * Release i_data_sem so that we can lock a page - page lock ranks
    + * above i_data_sem. i_mutex still protects us against file changes.
    + */
    + up_write(&iinfo->i_data_sem);

    page = find_or_create_page(inode->i_mapping, 0, GFP_NOFS);
    if (!page)
    @@ -181,6 +193,7 @@ int udf_expand_file_adinicb(struct inode
    SetPageUptodate(page);
    kunmap(page);
    }
    + down_write(&iinfo->i_data_sem);
    memset(iinfo->i_ext.i_data + iinfo->i_lenEAttr, 0x00,
    iinfo->i_lenAlloc);
    iinfo->i_lenAlloc = 0;
    @@ -190,17 +203,20 @@ int udf_expand_file_adinicb(struct inode
    iinfo->i_alloc_type = ICBTAG_FLAG_AD_LONG;
    /* from now on we have normal address_space methods */
    inode->i_data.a_ops = &udf_aops;
    + up_write(&iinfo->i_data_sem);
    err = inode->i_data.a_ops->writepage(page, &udf_wbc);
    if (err) {
    /* Restore everything back so that we don't lose data... */
    lock_page(page);
    kaddr = kmap(page);
    + down_write(&iinfo->i_data_sem);
    memcpy(iinfo->i_ext.i_data + iinfo->i_lenEAttr, kaddr,
    inode->i_size);
    kunmap(page);
    unlock_page(page);
    iinfo->i_alloc_type = ICBTAG_FLAG_AD_IN_ICB;
    inode->i_data.a_ops = &udf_adinicb_aops;
    + up_write(&iinfo->i_data_sem);
    }
    page_cache_release(page);
    mark_inode_dirty(inode);
    @@ -1105,10 +1121,9 @@ int udf_setsize(struct inode *inode, lof
    if (bsize <
    (udf_file_entry_alloc_offset(inode) + newsize)) {
    err = udf_expand_file_adinicb(inode);
    - if (err) {
    - up_write(&iinfo->i_data_sem);
    + if (err)
    return err;
    - }
    + down_write(&iinfo->i_data_sem);
    } else
    iinfo->i_lenAlloc = newsize;
    }



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