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    SubjectRe: [PATCH 16/21] sysfs: implement bin_buffer
    (We went off-list just now. Adding lkml again.)

    On 5/1/07, Tejun Heo <htejun@gmail.com> wrote:
    > Satyam Sharma wrote:
    > > On 4/28/07, Tejun Heo <htejun@gmail.com> wrote:
    > >> Implement bin_buffer which contains a mutex and pointer to PAGE_SIZE
    > >> buffer to properly synchronize accesses to per-openfile buffer and
    > >> prepare for immediate-kobj-disconnect.
    > >>
    > >> Signed-off-by: Tejun Heo <htejun@gmail.com>
    > >> ---
    > >> [...]
    > >> @@ -135,14 +160,22 @@ static int open(struct inode * inode, struct
    > >> file * file)
    > >> goto Error;
    > >>
    > >> error = -ENOMEM;
    > >> - file->private_data = kmalloc(PAGE_SIZE, GFP_KERNEL);
    > >> - if (!file->private_data)
    > >> + bb = kzalloc(sizeof(*bb), GFP_KERNEL);
    > >> + if (!bb)
    > >> goto Error;
    > >>
    > >> + bb->buffer = kmalloc(PAGE_SIZE, GFP_KERNEL);
    > >
    > > You could simply do a __get_free_page() here instead of a
    > > kmalloc(PAGE_SIZE).
    >
    > Yes, I could but 1. the original code was done using kmalloc

    Yes, I saw that, but you could change it just as well. In any case,
    this will only make fs/sysfs/bin.c similar to what is being done in
    fs/sysfs/file.c. We allocate the buffer page backing the attribute's
    data in fill_read_buffer() and fill_write_buffer() using
    get_zeroed_page() and not kzalloc().

    > 2. I'm not sure __get_free_page() is better than kmalloc(PAGE_SIZE, ), is it?

    If you know for sure that you require *exactly* PAGE_SIZE bytes, then
    yes, it is.
    -
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