add-buffer-head-related-helper-functions.patch

   1 Add buffer head related helper functions
   2
   3 From: Aneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com>
   4
   5 Add buffer head related helper function bh_uptodate_or_lock and
   6 bh_submit_read which can be used by file system
   7
   8 Signed-off-by: Aneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com>
   9 ---
  10
  11  fs/buffer.c                 |   44 +++++++++++++++++++++++++++++++++++++++++++
  12  include/linux/buffer_head.h |    2 ++
  13  2 files changed, 46 insertions(+), 0 deletions(-)
  14
  15
  16 diff --git a/fs/buffer.c b/fs/buffer.c
  17 index 7249e01..456c9ab 100644
  18 --- a/fs/buffer.c
  19 +++ b/fs/buffer.c
  20 @@ -3213,6 +3213,50 @@ static int buffer_cpu_notify(struct notifier_block *self,
  21         return NOTIFY_OK;
  22  }
  23
  24 +/**
  25 + * bh_uptodate_or_lock: Test whether the buffer is uptodate
  26 + * @bh: struct buffer_head
  27 + *
  28 + * Return true if the buffer is up-to-date and false,
  29 + * with the buffer locked, if not.
  30 + */
  31 +int bh_uptodate_or_lock(struct buffer_head *bh)
  32 +{
  33 +       if (!buffer_uptodate(bh)) {
  34 +               lock_buffer(bh);
  35 +               if (!buffer_uptodate(bh))
  36 +                       return 0;
  37 +               unlock_buffer(bh);
  38 +       }
  39 +       return 1;
  40 +}
  41 +EXPORT_SYMBOL(bh_uptodate_or_lock);
  42 +
  43 +/**
  44 + * bh_submit_read: Submit a locked buffer for reading
  45 + * @bh: struct buffer_head
  46 + *
  47 + * Returns zero on success and -EIO on error.
  48 + */
  49 +int bh_submit_read(struct buffer_head *bh)
  50 +{
  51 +       BUG_ON(!buffer_locked(bh));
  52 +
  53 +       if (buffer_uptodate(bh)) {
  54 +               unlock_buffer(bh);
  55 +               return 0;
  56 +       }
  57 +
  58 +       get_bh(bh);
  59 +       bh->b_end_io = end_buffer_read_sync;
  60 +       submit_bh(READ, bh);
  61 +       wait_on_buffer(bh);
  62 +       if (buffer_uptodate(bh))
  63 +               return 0;
  64 +       return -EIO;
  65 +}
  66 +EXPORT_SYMBOL(bh_submit_read);
  67 +
  68  void __init buffer_init(void)
  69  {
  70         int nrpages;
  71 diff --git a/include/linux/buffer_head.h b/include/linux/buffer_head.h
  72 index da0d83f..e98801f 100644
  73 --- a/include/linux/buffer_head.h
  74 +++ b/include/linux/buffer_head.h
  75 @@ -192,6 +192,8 @@ int sync_dirty_buffer(struct buffer_head *bh);
  76  int submit_bh(int, struct buffer_head *);
  77  void write_boundary_block(struct block_device *bdev,
  78                         sector_t bblock, unsigned blocksize);
  79 +int bh_uptodate_or_lock(struct buffer_head *bh);
  80 +int bh_submit_read(struct buffer_head *bh);
  81
  82  extern int buffer_heads_over_limit;
  83