lkml.org 
[lkml]   [2001]   [Jan]   [10]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
    Patch in this message
    /
    Date
    From
    Subject[PATCH] one-liner fix for bforget() honoring BH_Protected; was: Re: Patch (repost): cramfs memory corruption fix
    Linus Torvalds wrote:
    >
    > On Sat, 6 Jan 2001, Adam J. Richter wrote:
    > >
    > > This sounds like a bug that I posted a fix for a long time ago.
    > > cramfs calls bforget on the superblock area, destroying that block of
    > > the ramdisk, even when the ramdisk does not contain a cramfs file system.
    > > Normally, bforget is called on block that really can be trashed,
    > > such as blocks release by truncate or unlink.
    >
    > I'd really prefer just not letting bforget() touch BH_Protected buffers.
    > bforget() is also used by other things than unlink/truncate: it's used by
    > various partition codes etc, and it's used by the raid logic.

    Yup, I backed out Adam's one-liner in favor of the attached one-liner.
    Tested on 2.4.0, but should patch cleanly to just about anything. ;-)

    BTW Linus - you were of course right on the cramfs wanting 4096
    blocksize... but without this fix, that doesn't matter much. ;-)

    regards,
    David

    --
    David L. Parsley
    Network Administrator
    Roanoke College--- linux.linus/fs/buffer.c Wed Jan 3 23:45:26 2001
    +++ linux/fs/buffer.c Wed Jan 10 15:49:36 2001
    @@ -1145,13 +1145,15 @@
    * free list if it can.. We can NOT free the buffer if:
    * - there are other users of it
    * - it is locked and thus can have active IO
    + * - it is marked BH_Protected
    */
    void __bforget(struct buffer_head * buf)
    {
    /* grab the lru lock here to block bdflush. */
    spin_lock(&lru_list_lock);
    write_lock(&hash_table_lock);
    - if (!atomic_dec_and_test(&buf->b_count) || buffer_locked(buf))
    + if (!atomic_dec_and_test(&buf->b_count) || buffer_locked(buf) ||
    + buffer_protected(buf))
    goto in_use;
    __hash_unlink(buf);
    remove_inode_queue(buf);
    \
     
     \ /
      Last update: 2005-03-22 13:28    [W:0.029 / U:59.404 seconds]
    ©2003-2016 Jasper Spaans. hosted at Digital OceanAdvertise on this site