From e477b24b507998bc6568316a2e034025960d2404 Mon Sep 17 00:00:00 2001
From: Coly Li <colyli@suse.de>
Date: Fri, 21 Jul 2017 07:48:22 -0500
Subject: [PATCH] gfs2: add flag REQ_PRIO for metadata I/O
When gfs2 does metadata I/O, only REQ_META is used as a metadata hint of
the bio. But flag REQ_META is just a hint for block trace, not for block
layer code to handle a bio as metadata request.
For some of metadata I/Os of gfs2, A REQ_PRIO flag on the metadata bio
would be very informative to block layer code. For example, if bcache is
used as a I/O cache for gfs2, it will be possible for bcache code to get
the hint and cache the pre-fetched metadata blocks on cache device. This
behavior may be helpful to improve metadata I/O performance if the
following requests hit the cache.
Here are the locations in gfs2 code where a REQ_PRIO flag should be added,
- All places where REQ_READAHEAD is used, gfs2 code uses this flag for
metadata read ahead.
- In gfs2_meta_rq() where the first metadata block is read in.
- In gfs2_write_buf_to_page(), read in quota metadata blocks to have them
up to date.
These metadata blocks are probably to be accessed again in future, adding
a REQ_PRIO flag may have bcache to keep such metadata in fast cache
device. For system without a cache layer, REQ_PRIO can still provide hint
to block layer to handle metadata requests more properly.
Signed-off-by: Coly Li <colyli@suse.de>
Signed-off-by: Bob Peterson <rpeterso@redhat.com>
---
fs/gfs2/bmap.c | 5 +++--
fs/gfs2/dir.c | 4 +++-
fs/gfs2/meta_io.c | 6 ++++--
fs/gfs2/quota.c | 2 +-
4 files changed, 11 insertions(+), 6 deletions(-)
diff --git a/fs/gfs2/bmap.c b/fs/gfs2/bmap.c
index 9fa3aef9a5b3..fa3ea29f39cf 100644
--- a/fs/gfs2/bmap.c
+++ b/fs/gfs2/bmap.c
@@ -291,8 +291,9 @@ static void gfs2_metapath_ra(struct gfs2_glock *gl,
if (trylock_buffer(rabh)) {
if (!buffer_uptodate(rabh)) {
rabh->b_end_io = end_buffer_read_sync;
- submit_bh(REQ_OP_READ, REQ_RAHEAD | REQ_META,
- rabh);
+ submit_bh(REQ_OP_READ,
+ REQ_RAHEAD | REQ_META | REQ_PRIO,
+ rabh);
continue;
}
unlock_buffer(rabh);
diff --git a/fs/gfs2/dir.c b/fs/gfs2/dir.c
index db427658ccd9..0741e4018f8c 100644
--- a/fs/gfs2/dir.c
+++ b/fs/gfs2/dir.c
@@ -1514,7 +1514,9 @@ static void gfs2_dir_readahead(struct inode *inode, unsigned hsize, u32 index,
continue;
}
bh->b_end_io = end_buffer_read_sync;
- submit_bh(REQ_OP_READ, REQ_RAHEAD | REQ_META, bh);
+ submit_bh(REQ_OP_READ,
+ REQ_RAHEAD | REQ_META | REQ_PRIO,
+ bh);
continue;
}
brelse(bh);
diff --git a/fs/gfs2/meta_io.c b/fs/gfs2/meta_io.c
index 4da7745c890a..61ef6c9be816 100644
--- a/fs/gfs2/meta_io.c
+++ b/fs/gfs2/meta_io.c
@@ -453,7 +453,7 @@ struct buffer_head *gfs2_meta_ra(struct gfs2_glock *gl, u64 dblock, u32 extlen)
if (buffer_uptodate(first_bh))
goto out;
if (!buffer_locked(first_bh))
- ll_rw_block(REQ_OP_READ, REQ_META, 1, &first_bh);
+ ll_rw_block(REQ_OP_READ, REQ_META | REQ_PRIO, 1, &first_bh);
dblock++;
extlen--;
@@ -462,7 +462,9 @@ struct buffer_head *gfs2_meta_ra(struct gfs2_glock *gl, u64 dblock, u32 extlen)
bh = gfs2_getbuf(gl, dblock, CREATE);
if (!buffer_uptodate(bh) && !buffer_locked(bh))
- ll_rw_block(REQ_OP_READ, REQ_RAHEAD | REQ_META, 1, &bh);
+ ll_rw_block(REQ_OP_READ,
+ REQ_RAHEAD | REQ_META | REQ_PRIO,
+ 1, &bh);
brelse(bh);
dblock++;
extlen--;
diff --git a/fs/gfs2/quota.c b/fs/gfs2/quota.c
index c2ca9566b764..739adf105d7f 100644
--- a/fs/gfs2/quota.c
+++ b/fs/gfs2/quota.c
@@ -730,7 +730,7 @@ static int gfs2_write_buf_to_page(struct gfs2_inode *ip, unsigned long index,
if (PageUptodate(page))
set_buffer_uptodate(bh);
if (!buffer_uptodate(bh)) {
- ll_rw_block(REQ_OP_READ, REQ_META, 1, &bh);
+ ll_rw_block(REQ_OP_READ, REQ_META | REQ_PRIO, 1, &bh);
wait_on_buffer(bh);
if (!buffer_uptodate(bh))
goto unlock_out;
--
2.30.9