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Commit 389d1b08 authored by Aneesh Kumar K.V's avatar Aneesh Kumar K.V Committed by Theodore Ts'o
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Add buffer head related helper functions 



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

Signed-off-by: default avatarAneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com>
parent bb4f397a

fs/buffer.c

+44 −0
Original line number Diff line number Diff line
@@ -3213,6 +3213,50 @@ 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 zero on success and -EIO on error.

 */

int bh_submit_read(struct buffer_head *bh)

{

	BUG_ON(!buffer_locked(bh));



	if (buffer_uptodate(bh)) {

		unlock_buffer(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;

include/linux/buffer_head.h

+2 −0
Original line number Diff line number Diff line
@@ -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;