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Commit 39b0555f authored by Andreas Gruenbacher's avatar Andreas Gruenbacher Committed by Bob Peterson
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gfs2: Extended attribute readahead optimization 



Instead of submitting a READ_SYNC bio for the inode and a READA bio for
the inode's extended attributes through submit_bh, submit a single READ_SYNC
bio for both through submit_bio when possible.  This can be more
efficient on some kinds of block devices.

Signed-off-by: default avatarAndreas Gruenbacher <agruenba@redhat.com>
Signed-off-by: default avatarBob Peterson <rpeterso@redhat.com>
parent c8d57703

fs/gfs2/meta_io.c

+63 −18
Original line number Diff line number Diff line
@@ -187,19 +187,50 @@ struct buffer_head *gfs2_meta_new(struct gfs2_glock *gl, u64 blkno) 
	return bh;

}



static void gfs2_meta_readahead(struct gfs2_glock *gl, u64 blkno)

static void gfs2_meta_read_endio(struct bio *bio)

{

	struct buffer_head *bh;

	struct bio_vec *bvec;

	int i;



	bh = gfs2_getbuf(gl, blkno, 1);

	lock_buffer(bh);

	if (buffer_uptodate(bh)) {

		unlock_buffer(bh);

		brelse(bh);

	bio_for_each_segment_all(bvec, bio, i) {

		struct page *page = bvec->bv_page;

		struct buffer_head *bh = page_buffers(page);

		unsigned int len = bvec->bv_len;



		while (bh_offset(bh) < bvec->bv_offset)

			bh = bh->b_this_page;

		do {

			struct buffer_head *next = bh->b_this_page;

			len -= bh->b_size;

			bh->b_end_io(bh, !bio->bi_error);

			bh = next;

		} while (bh && len);

	}

	bio_put(bio);

}



/*

 * Submit several consecutive buffer head I/O requests as a single bio I/O

 * request.  (See submit_bh_wbc.)

 */

static void gfs2_submit_bhs(int rw, struct buffer_head *bhs[], int num)

{

	struct buffer_head *bh = bhs[0];

	struct bio *bio;

	int i;



	if (!num)

		return;



	bio = bio_alloc(GFP_NOIO, num);

	bio->bi_iter.bi_sector = bh->b_blocknr * (bh->b_size >> 9);

	bio->bi_bdev = bh->b_bdev;

	for (i = 0; i < num; i++) {

		bh = bhs[i];

		bio_add_page(bio, bh->b_page, bh->b_size, bh_offset(bh));

	}

	bh->b_end_io = end_buffer_read_sync;

	submit_bh(READA | REQ_META | REQ_PRIO, bh);

	bio->bi_end_io = gfs2_meta_read_endio;

	submit_bio(rw, bio);

}



/**
@@ -216,7 +247,8 @@ int gfs2_meta_read(struct gfs2_glock *gl, u64 blkno, int flags, 
		   int rahead, struct buffer_head **bhp)

{

	struct gfs2_sbd *sdp = gl->gl_name.ln_sbd;

	struct buffer_head *bh;

	struct buffer_head *bh, *bhs[2];

	int num = 0;



	if (unlikely(test_bit(SDF_SHUTDOWN, &sdp->sd_flags))) {

		*bhp = NULL;
@@ -228,18 +260,31 @@ int gfs2_meta_read(struct gfs2_glock *gl, u64 blkno, int flags, 
	lock_buffer(bh);

	if (buffer_uptodate(bh)) {

		unlock_buffer(bh);

		if (rahead)

			gfs2_meta_readahead(gl, blkno + 1);

		return 0;

	}

		flags &= ~DIO_WAIT;

	} else {

		bh->b_end_io = end_buffer_read_sync;

		get_bh(bh);

	submit_bh(READ_SYNC | REQ_META | REQ_PRIO, bh);

	if (rahead)

		gfs2_meta_readahead(gl, blkno + 1);

		bhs[num++] = bh;

	}



	if (rahead) {

		bh = gfs2_getbuf(gl, blkno + 1, CREATE);



		lock_buffer(bh);

		if (buffer_uptodate(bh)) {

			unlock_buffer(bh);

			brelse(bh);

		} else {

			bh->b_end_io = end_buffer_read_sync;

			bhs[num++] = bh;

		}

	}



	gfs2_submit_bhs(READ_SYNC | REQ_META | REQ_PRIO, bhs, num);

	if (!(flags & DIO_WAIT))

		return 0;



	bh = *bhp;

	wait_on_buffer(bh);

	if (unlikely(!buffer_uptodate(bh))) {

		struct gfs2_trans *tr = current->journal_info;