lkml.org 
[lkml]   [2012]   [Mar]   [12]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
    Patch in this message
    /
    From
    Subject[34-longterm 124/196] GFS2: BUG in gfs2_adjust_quota
    Date
    From: Abhijith Das <adas@redhat.com>

    -------------------
    This is a commit scheduled for the next v2.6.34 longterm release.
    If you see a problem with using this for longterm, please comment.
    -------------------

    commit 8b4216018bdbfbb1b76150d202b15ee68c38e991 upstream.

    HighMem pages on i686 do not get mapped to the buffer_heads and this was
    causing a NULL pointer dereference when we were trying to memset page buffers
    to zero.
    We now use zero_user() that kmaps the page and directly manipulates page data.
    This patch also fixes a boundary condition that was incorrect.

    Signed-off-by: Abhi Das <adas@redhat.com>
    Signed-off-by: Steven Whitehouse <swhiteho@redhat.com>
    Signed-off-by: Paul Gortmaker <paul.gortmaker@windriver.com>
    ---
    fs/gfs2/quota.c | 8 +++-----
    1 file changed, 3 insertions(+), 5 deletions(-)

    diff --git a/fs/gfs2/quota.c b/fs/gfs2/quota.c
    index f1c8d79..f9358a2 100644
    --- a/fs/gfs2/quota.c
    +++ b/fs/gfs2/quota.c
    @@ -694,10 +694,8 @@ get_a_page:
    if (!buffer_mapped(bh))
    goto unlock_out;
    /* If it's a newly allocated disk block for quota, zero it */
    - if (buffer_new(bh)) {
    - memset(bh->b_data, 0, bh->b_size);
    - set_buffer_uptodate(bh);
    - }
    + if (buffer_new(bh))
    + zero_user(page, pos - blocksize, bh->b_size);
    }

    if (PageUptodate(page))
    @@ -723,7 +721,7 @@ get_a_page:

    /* If quota straddles page boundary, we need to update the rest of the
    * quota at the beginning of the next page */
    - if (offset != 0) { /* first page, offset is closer to PAGE_CACHE_SIZE */
    + if ((offset + sizeof(struct gfs2_quota)) > PAGE_CACHE_SIZE) {
    ptr = ptr + nbytes;
    nbytes = sizeof(struct gfs2_quota) - nbytes;
    offset = 0;
    --
    1.7.9.3


    \
     
     \ /
      Last update: 2012-03-13 01:51    [W:4.072 / U:0.852 seconds]
    ©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site