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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: Andreas Gruenbacher <agruenba@redhat.com>
Signed-off-by: Bob Peterson <rpeterso@redhat.com>
This commit is contained in:
Andreas Gruenbacher 2015-11-13 07:44:57 -06:00 committed by Bob Peterson
parent c8d5770384
commit 39b0555f7a
1 changed files with 64 additions and 19 deletions
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83
fs/gfs2/meta_io.c
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@ -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);
return;
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);
}
bh->b_end_io = end_buffer_read_sync;
submit_bh(READA | REQ_META | REQ_PRIO, bh);
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));
}
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);
bhs[num++] = bh;
}
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);
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;