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Subject[PATCH 23/49] Add buffer head related helper functions
Date
From: Aneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com>

Add buffer head related helper function bh_uptodate_or_lock and
bh_submit_read which can be used by file system

Signed-off-by: Aneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com>
---
fs/buffer.c | 41 +++++++++++++++++++++++++++++++++++++++++
include/linux/buffer_head.h | 2 ++
2 files changed, 43 insertions(+), 0 deletions(-)
diff --git a/fs/buffer.c b/fs/buffer.c
index 7249e01..7593ff3 100644
--- a/fs/buffer.c
+++ b/fs/buffer.c
@@ -3213,6 +3213,47 @@ static int buffer_cpu_notify(struct notifier_block *self,
return NOTIFY_OK;
}

+/**
+ * bh_uptodate_or_lock: Test whether the buffer is uptodate
+ * @bh: struct buffer_head
+ *
+ * Return true if the buffer is up-to-date and false,
+ * with the buffer locked, if not.
+ */
+int bh_uptodate_or_lock(struct buffer_head *bh)
+{
+ if (!buffer_uptodate(bh)) {
+ lock_buffer(bh);
+ if (!buffer_uptodate(bh))
+ return 0;
+ unlock_buffer(bh);
+ }
+ return 1;
+}
+EXPORT_SYMBOL(bh_uptodate_or_lock);
+/**
+ * bh_submit_read: Submit a locked buffer for reading
+ * @bh: struct buffer_head
+ *
+ * Returns a negative error
+ */
+int bh_submit_read(struct buffer_head *bh)
+{
+ if (!buffer_locked(bh))
+ lock_buffer(bh);
+
+ if (buffer_uptodate(bh))
+ return 0;
+
+ get_bh(bh);
+ bh->b_end_io = end_buffer_read_sync;
+ submit_bh(READ, bh);
+ wait_on_buffer(bh);
+ if (buffer_uptodate(bh))
+ return 0;
+ return -EIO;
+}
+EXPORT_SYMBOL(bh_submit_read);
void __init buffer_init(void)
{
int nrpages;
diff --git a/include/linux/buffer_head.h b/include/linux/buffer_head.h
index da0d83f..e98801f 100644
--- a/include/linux/buffer_head.h
+++ b/include/linux/buffer_head.h
@@ -192,6 +192,8 @@ int sync_dirty_buffer(struct buffer_head *bh);
int submit_bh(int, struct buffer_head *);
void write_boundary_block(struct block_device *bdev,
sector_t bblock, unsigned blocksize);
+int bh_uptodate_or_lock(struct buffer_head *bh);
+int bh_submit_read(struct buffer_head *bh);

extern int buffer_heads_over_limit;

--
1.5.4.rc3.31.g1271-dirty


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