Instead of submitting separate bio for the inode and its extended
attributes, submit a single bio for both when possible. The entire
request becomes a normal read, not a readahead.
To keep track of the buffer heads that make up the bio, we allocate
temporary buffer head arrays: in the endio handler, it would also be
possible to compute the buffer head block numbers from the bio and to
grab the buffer heads with gfs2_getbuf, but the code would become even
messier.
---
fs/gfs2/meta_io.c | 94 ++++++++++++++++++++++++++++++++++++++++++++-----------
1 file changed, 76 insertions(+), 18 deletions(-)
diff --git a/fs/gfs2/meta_io.c b/fs/gfs2/meta_io.c
index 0f24828..e650127 100644
--- a/fs/gfs2/meta_io.c
+++ b/fs/gfs2/meta_io.c
@@ -187,19 +187,63 @@ 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)
+struct gfs2_meta_read {
+ int num;
+ struct buffer_head *bhs[0];
+};
+
+static void gfs2_meta_read_endio(struct bio *bio) {
+ struct gfs2_meta_read *r = bio->bi_private;
+ int i;
+
+ for (i = 0; i < r->num; i++) {
+ struct buffer_head *bh = r->bhs[i];
+
+ if (unlikely(bio_flagged(bio, BIO_QUIET)))
+ set_bit(BH_Quiet, &bh->b_state);
+
+ bh->b_end_io(bh, !bio->bi_error);
+ }
+ bio_put(bio);
+ kfree(r);
+}
+
+/*
+ * (See submit_bh_wbc.)
+ */
+static void gfs2_submit_bhs(int rw, struct buffer_head *bhs[], int num)
{
- struct buffer_head *bh;
+ struct gfs2_meta_read *r;
+ struct buffer_head *bh = bhs[0];
+ struct bio *bio;
+ int i;
- bh = gfs2_getbuf(gl, blkno, 1);
- lock_buffer(bh);
- if (buffer_uptodate(bh)) {
- unlock_buffer(bh);
- brelse(bh);
+ if (!num)
+ return;
+
+ if (num == 1) {
+ bh->b_end_io = end_buffer_read_sync;
+ submit_bh(rw, bh);
return;
}
- bh->b_end_io = end_buffer_read_sync;
- submit_bh(READA | REQ_META | REQ_PRIO, bh);
+
+ r = kmalloc(sizeof(*r) + num * sizeof(r->bhs[0]),
+ GFP_NOIO | __GFP_NOFAIL);
+ r->num = num;
+ for (i = 0; i < num; i++)
+ r->bhs[i] = bhs[i];
+
+ 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;
+ bio->bi_private = r;
+
+ submit_bio(rw, bio);
}
/**
@@ -216,7 +260,8 @@ 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 +273,31 @@ 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;
--
2.5.0
