[GFS2] Move pin/unpin into lops.c, clean up locking

gfs2_pin and gfs2_unpin are only used in lops.c, despite being
defined in meta_io.c, so this patch moves them into lops.c and
makes them static. At the same time, its possible to clean up
the locking in the buf and databuf _lo_add() functions so that
we only need to grab the spinlock once. Also we have to move
lock_buffer() around the _lo_add() functions since we can't
do that in gfs2_pin() any more since we hold the spinlock
for the duration of that function.

As a result, the code shrinks by 12 lines and we do far fewer
operations when adding buffers to the log. It also makes the
code somewhat easier to read & understand.

Signed-off-by: Steven Whitehouse <swhiteho@redhat.com>

1 files changed, 89 insertions, 28 deletions

diff --git a/fs/gfs2/lops.c b/fs/gfs2/lops.c
index 7ef335623373..3ec587135d46 100644
--- a/fs/gfs2/lops.c
+++ b/fs/gfs2/lops.c
@@ -27,7 +27,71 @@
 #include "trans.h"
 #include "util.h"
 
-static void glock_lo_add(struct gfs2_sbd *sdp, struct gfs2_log_element *le)
+/**
+ * gfs2_pin - Pin a buffer in memory
+ * @sdp: The superblock
+ * @bh: The buffer to be pinned
+ *
+ * The log lock must be held when calling this function
+ */
+static void gfs2_pin(struct gfs2_sbd *sdp, struct buffer_head *bh)
+{
+        struct gfs2_bufdata *bd;
+
+        gfs2_assert_withdraw(sdp, test_bit(SDF_JOURNAL_LIVE, &sdp->sd_flags));
+
+        clear_buffer_dirty(bh);
+        if (test_set_buffer_pinned(bh))
+                gfs2_assert_withdraw(sdp, 0);
+        if (!buffer_uptodate(bh))
+                gfs2_io_error_bh(sdp, bh);
+        bd = bh->b_private;
+        /* If this buffer is in the AIL and it has already been written
+         * to in-place disk block, remove it from the AIL.
+         */
+        if (bd->bd_ail)
+                list_move(&bd->bd_ail_st_list, &bd->bd_ail->ai_ail2_list);
+        get_bh(bh);
+}
+
+/**
+ * gfs2_unpin - Unpin a buffer
+ * @sdp: the filesystem the buffer belongs to
+ * @bh: The buffer to unpin
+ * @ai:
+ *
+ */
+
+static void gfs2_unpin(struct gfs2_sbd *sdp, struct buffer_head *bh,
+                       struct gfs2_ail *ai)
+{
+        struct gfs2_bufdata *bd = bh->b_private;
+
+        gfs2_assert_withdraw(sdp, buffer_uptodate(bh));
+
+        if (!buffer_pinned(bh))
+                gfs2_assert_withdraw(sdp, 0);
+
+        lock_buffer(bh);
+        mark_buffer_dirty(bh);
+        clear_buffer_pinned(bh);
+
+        gfs2_log_lock(sdp);
+        if (bd->bd_ail) {
+                list_del(&bd->bd_ail_st_list);
+                brelse(bh);
+        } else {
+                struct gfs2_glock *gl = bd->bd_gl;
+                list_add(&bd->bd_ail_gl_list, &gl->gl_ail_list);
+                atomic_inc(&gl->gl_ail_count);
+        }
+        bd->bd_ail = ai;
+        list_add(&bd->bd_ail_st_list, &ai->ai_ail1_list);
+        gfs2_log_unlock(sdp);
+        unlock_buffer(bh);
+}
+
+static void __glock_lo_add(struct gfs2_sbd *sdp, struct gfs2_log_element *le)
 {
         struct gfs2_glock *gl;
         struct gfs2_trans *tr = current->journal_info;
@@ -38,15 +102,19 @@ static void glock_lo_add(struct gfs2_sbd *sdp, struct gfs2_log_element *le)
         if (gfs2_assert_withdraw(sdp, gfs2_glock_is_held_excl(gl)))
                 return;
 
-        gfs2_log_lock(sdp);
-        if (!list_empty(&le->le_list)){
-                gfs2_log_unlock(sdp);
+        if (!list_empty(&le->le_list))
                 return;
-        }
+
         gfs2_glock_hold(gl);
         set_bit(GLF_DIRTY, &gl->gl_flags);
         sdp->sd_log_num_gl++;
         list_add(&le->le_list, &sdp->sd_log_le_gl);
+}
+
+static void glock_lo_add(struct gfs2_sbd *sdp, struct gfs2_log_element *le)
+{
+        gfs2_log_lock(sdp);
+        __glock_lo_add(sdp, le);
         gfs2_log_unlock(sdp);
 }
 
@@ -71,30 +139,25 @@ static void buf_lo_add(struct gfs2_sbd *sdp, struct gfs2_log_element *le)
         struct gfs2_bufdata *bd = container_of(le, struct gfs2_bufdata, bd_le);
         struct gfs2_trans *tr;
 
+        lock_buffer(bd->bd_bh);
         gfs2_log_lock(sdp);
-        if (!list_empty(&bd->bd_list_tr)) {
-                gfs2_log_unlock(sdp);
-                return;
-        }
+        if (!list_empty(&bd->bd_list_tr))
+                goto out;
         tr = current->journal_info;
         tr->tr_touched = 1;
         tr->tr_num_buf++;
         list_add(&bd->bd_list_tr, &tr->tr_list_buf);
-        gfs2_log_unlock(sdp);
-
         if (!list_empty(&le->le_list))
-                return;
-
-        gfs2_trans_add_gl(bd->bd_gl);
-
+                goto out;
+        __glock_lo_add(sdp, &bd->bd_gl->gl_le);
         gfs2_meta_check(sdp, bd->bd_bh);
         gfs2_pin(sdp, bd->bd_bh);
-        gfs2_log_lock(sdp);
         sdp->sd_log_num_buf++;
         list_add(&le->le_list, &sdp->sd_log_le_buf);
-        gfs2_log_unlock(sdp);
-
         tr->tr_num_buf_new++;
+out:
+        gfs2_log_unlock(sdp);
+        unlock_buffer(bd->bd_bh);
 }
 
 static void buf_lo_incore_commit(struct gfs2_sbd *sdp, struct gfs2_trans *tr)
@@ -476,31 +539,29 @@ static void databuf_lo_add(struct gfs2_sbd *sdp, struct gfs2_log_element *le)
         struct address_space *mapping = bd->bd_bh->b_page->mapping;
         struct gfs2_inode *ip = GFS2_I(mapping->host);
 
+        lock_buffer(bd->bd_bh);
         gfs2_log_lock(sdp);
-        if (!list_empty(&bd->bd_list_tr)) {
-                gfs2_log_unlock(sdp);
-                return;
-        }
+        if (!list_empty(&bd->bd_list_tr))
+                goto out;
         tr->tr_touched = 1;
         if (gfs2_is_jdata(ip)) {
                 tr->tr_num_buf++;
                 list_add(&bd->bd_list_tr, &tr->tr_list_buf);
         }
-        gfs2_log_unlock(sdp);
         if (!list_empty(&le->le_list))
-                return;
+                goto out;
 
-        gfs2_trans_add_gl(bd->bd_gl);
+        __glock_lo_add(sdp, &bd->bd_gl->gl_le);
         if (gfs2_is_jdata(ip)) {
                 gfs2_pin(sdp, bd->bd_bh);
                 tr->tr_num_databuf_new++;
-        }
-        gfs2_log_lock(sdp);
-        if (gfs2_is_jdata(ip))
                 sdp->sd_log_num_jdata++;
+        }
         sdp->sd_log_num_databuf++;
         list_add(&le->le_list, &sdp->sd_log_le_databuf);
+out:
         gfs2_log_unlock(sdp);
+        unlock_buffer(bd->bd_bh);
 }
 
 static int gfs2_check_magic(struct buffer_head *bh)