[GFS2] Clean up gfs2_trans_add_revoke()

The following alters gfs2_trans_add_revoke() to take a struct
gfs2_bufdata as an argument. This eliminates the memory allocation which
was previously required by making use of the already existing struct
gfs2_bufdata. It makes some sanity checks to ensure that the
gfs2_bufdata has been removed from all the lists before its recycled as
a revoke structure. This saves one memory allocation and one free per
revoke structure.

Also as a result, and to simplify the locking, since there is no longer
any blocking code in gfs2_trans_add_revoke() we must hold the log lock
whenever this function is called. This reduces the amount of times we
take and unlock the log lock.

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

6 files changed, 25 insertions, 43 deletions

diff --git a/fs/gfs2/glops.c b/fs/gfs2/glops.c
index b17346a355bf..4670dcb2a877 100644
--- a/fs/gfs2/glops.c
+++ b/fs/gfs2/glops.c
@@ -41,7 +41,6 @@ static void gfs2_ail_empty_gl(struct gfs2_glock *gl)
         struct list_head *head = &gl->gl_ail_list;
         struct gfs2_bufdata *bd;
         struct buffer_head *bh;
-        u64 blkno;
         int error;
 
         blocks = atomic_read(&gl->gl_ail_count);
@@ -57,15 +56,12 @@ static void gfs2_ail_empty_gl(struct gfs2_glock *gl)
                 bd = list_entry(head->next, struct gfs2_bufdata,
                                 bd_ail_gl_list);
                 bh = bd->bd_bh;
-                blkno = bh->b_blocknr;
-                gfs2_assert_withdraw(sdp, !buffer_busy(bh));
-
                 gfs2_remove_from_ail(NULL, bd);
-                gfs2_log_unlock(sdp);
-
-                gfs2_trans_add_revoke(sdp, blkno);
-
-                gfs2_log_lock(sdp);
+                bd->bd_bh = NULL;
+                bh->b_private = NULL;
+                bd->bd_blkno = bh->b_blocknr;
+                gfs2_assert_withdraw(sdp, !buffer_busy(bh));
+                gfs2_trans_add_revoke(sdp, bd);
         }
         gfs2_assert_withdraw(sdp, !atomic_read(&gl->gl_ail_count));
         gfs2_log_unlock(sdp);
diff --git a/fs/gfs2/log.c b/fs/gfs2/log.c
index 20fa528d457d..4d04e6f19706 100644
--- a/fs/gfs2/log.c
+++ b/fs/gfs2/log.c
@@ -71,8 +71,8 @@ unsigned int gfs2_struct2blk(struct gfs2_sbd *sdp, unsigned int nstruct,
 void gfs2_remove_from_ail(struct address_space *mapping, struct gfs2_bufdata *bd)
 {
         bd->bd_ail = NULL;
-        list_del(&bd->bd_ail_st_list);
-        list_del(&bd->bd_ail_gl_list);
+        list_del_init(&bd->bd_ail_st_list);
+        list_del_init(&bd->bd_ail_gl_list);
         atomic_dec(&bd->bd_gl->gl_ail_count);
         if (mapping)
                 gfs2_meta_cache_flush(GFS2_I(mapping->host));
diff --git a/fs/gfs2/lops.c b/fs/gfs2/lops.c
index 4cbef4c23a6b..342c10e12af2 100644
--- a/fs/gfs2/lops.c
+++ b/fs/gfs2/lops.c
@@ -343,11 +343,8 @@ static void revoke_lo_add(struct gfs2_sbd *sdp, struct gfs2_log_element *le)
         tr = current->journal_info;
         tr->tr_touched = 1;
         tr->tr_num_revoke++;
-
-        gfs2_log_lock(sdp);
         sdp->sd_log_num_revoke++;
         list_add(&le->le_list, &sdp->sd_log_le_revoke);
-        gfs2_log_unlock(sdp);
 }
 
 static void revoke_lo_before_commit(struct gfs2_sbd *sdp)
diff --git a/fs/gfs2/meta_io.c b/fs/gfs2/meta_io.c
index d762e4f7044e..19097bc7c81d 100644
--- a/fs/gfs2/meta_io.c
+++ b/fs/gfs2/meta_io.c
@@ -313,42 +313,31 @@ void gfs2_meta_wipe(struct gfs2_inode *ip, u64 bstart, u32 blen)
         while (blen) {
                 bh = getbuf(ip->i_gl, bstart, NO_CREATE);
                 if (bh) {
-                        struct gfs2_bufdata *bd = bh->b_private;
+                        struct gfs2_bufdata *bd;
 
+                        lock_buffer(bh);
+                        gfs2_log_lock(sdp);
+                        bd = bh->b_private;
                         if (test_clear_buffer_pinned(bh)) {
                                 struct gfs2_trans *tr = current->journal_info;
-                                struct gfs2_inode *bh_ip =
-                                        GFS2_I(bh->b_page->mapping->host);
-
-                                gfs2_log_lock(sdp);
                                 list_del_init(&bd->bd_le.le_list);
                                 gfs2_assert_warn(sdp, sdp->sd_log_num_buf);
                                 sdp->sd_log_num_buf--;
-                                gfs2_log_unlock(sdp);
-                                if (bh_ip->i_inode.i_private != NULL)
-                                        tr->tr_num_databuf_rm++;
-                                else
-                                        tr->tr_num_buf_rm++;
+                                tr->tr_num_buf_rm++;
                                 brelse(bh);
                         }
                         if (bd) {
-                                gfs2_log_lock(sdp);
                                 if (bd->bd_ail) {
-                                        u64 blkno = bh->b_blocknr;
-                                        bd->bd_ail = NULL;
-                                        list_del(&bd->bd_ail_st_list);
-                                        list_del(&bd->bd_ail_gl_list);
-                                        atomic_dec(&bd->bd_gl->gl_ail_count);
-                                        brelse(bh);
-                                        gfs2_log_unlock(sdp);
-                                        gfs2_trans_add_revoke(sdp, blkno);
-                                } else
-                                        gfs2_log_unlock(sdp);
+                                        gfs2_remove_from_ail(NULL, bd);
+                                        bh->b_private = NULL;
+                                        bd->bd_bh = NULL;
+                                        bd->bd_blkno = bh->b_blocknr;
+                                        gfs2_trans_add_revoke(sdp, bd);
+                                }
                         }
-
-                        lock_buffer(bh);
                         clear_buffer_dirty(bh);
                         clear_buffer_uptodate(bh);
+                        gfs2_log_unlock(sdp);
                         unlock_buffer(bh);
 
                         brelse(bh);
diff --git a/fs/gfs2/trans.c b/fs/gfs2/trans.c
index 01cc27fefd84..717983e2c2ae 100644
--- a/fs/gfs2/trans.c
+++ b/fs/gfs2/trans.c
@@ -142,12 +142,12 @@ void gfs2_trans_add_bh(struct gfs2_glock *gl, struct buffer_head *bh, int meta)
         lops_add(sdp, &bd->bd_le);
 }
 
-void gfs2_trans_add_revoke(struct gfs2_sbd *sdp, u64 blkno)
+void gfs2_trans_add_revoke(struct gfs2_sbd *sdp, struct gfs2_bufdata *bd)
 {
-        struct gfs2_bufdata *bd = kmem_cache_alloc(gfs2_bufdata_cachep,
-                                          GFP_NOFS | __GFP_NOFAIL);
+        BUG_ON(!list_empty(&bd->bd_le.le_list));
+        BUG_ON(!list_empty(&bd->bd_ail_st_list));
+        BUG_ON(!list_empty(&bd->bd_ail_gl_list));
         lops_init_le(&bd->bd_le, &gfs2_revoke_lops);
-        bd->bd_blkno = blkno;
         lops_add(sdp, &bd->bd_le);
 }
 
@@ -160,7 +160,7 @@ void gfs2_trans_add_unrevoke(struct gfs2_sbd *sdp, u64 blkno)
 
         list_for_each_entry(bd, &sdp->sd_log_le_revoke, bd_le.le_list) {
                 if (bd->bd_blkno == blkno) {
-                        list_del(&bd->bd_le.le_list);
+                        list_del_init(&bd->bd_le.le_list);
                         gfs2_assert_withdraw(sdp, sdp->sd_log_num_revoke);
                         sdp->sd_log_num_revoke--;
                         found = 1;
diff --git a/fs/gfs2/trans.h b/fs/gfs2/trans.h
index 23d4cbe1de5b..043d5f4b9c4c 100644
--- a/fs/gfs2/trans.h
+++ b/fs/gfs2/trans.h
@@ -32,7 +32,7 @@ void gfs2_trans_end(struct gfs2_sbd *sdp);
 
 void gfs2_trans_add_gl(struct gfs2_glock *gl);
 void gfs2_trans_add_bh(struct gfs2_glock *gl, struct buffer_head *bh, int meta);
-void gfs2_trans_add_revoke(struct gfs2_sbd *sdp, u64 blkno);
+void gfs2_trans_add_revoke(struct gfs2_sbd *sdp, struct gfs2_bufdata *bd);
 void gfs2_trans_add_unrevoke(struct gfs2_sbd *sdp, u64 blkno);
 void gfs2_trans_add_rg(struct gfs2_rgrpd *rgd);