GFS2: replace gfs2_ail structure with gfs2_trans

In order to allow transactions and log flushes to happen at the same
time, gfs2 needs to move the transaction accounting and active items
list code into the gfs2_trans structure.  As a first step toward this,
this patch removes the gfs2_ail structure, and handles the active items
list in the gfs_trans structure.  This keeps gfs2 from allocating an ail
structure on log flushes, and gives us a struture that can later be used
to store the transaction accounting outside of the gfs2 superblock
structure.

With this patch, at the end of a transaction, gfs2 will add the
gfs2_trans structure to the superblock if there is not one already.
This structure now has the active items fields that were previously in
gfs2_ail.  This is not necessary in the case where the transaction was
simply used to add revokes, since these are never written outside of the
journal, and thus, don't need an active items list.

Also, in order to make sure that the transaction structure is not
removed while it's still in use by gfs2_trans_end, unlocking the
sd_log_flush_lock has to happen slightly later in ending the
transaction.

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

1 files changed, 57 insertions, 47 deletions

diff --git a/fs/gfs2/log.c b/fs/gfs2/log.c
index 9a2ca8be7647..b404f4853034 100644
--- a/fs/gfs2/log.c
+++ b/fs/gfs2/log.c
@@ -73,7 +73,7 @@ unsigned int gfs2_struct2blk(struct gfs2_sbd *sdp, unsigned int nstruct,
 
 void gfs2_remove_from_ail(struct gfs2_bufdata *bd)
 {
-        bd->bd_ail = NULL;
+        bd->bd_tr = NULL;
         list_del_init(&bd->bd_ail_st_list);
         list_del_init(&bd->bd_ail_gl_list);
         atomic_dec(&bd->bd_gl->gl_ail_count);
@@ -90,7 +90,7 @@ void gfs2_remove_from_ail(struct gfs2_bufdata *bd)
 
 static int gfs2_ail1_start_one(struct gfs2_sbd *sdp,
                                struct writeback_control *wbc,
-                               struct gfs2_ail *ai)
+                               struct gfs2_trans *tr)
 __releases(&sdp->sd_ail_lock)
 __acquires(&sdp->sd_ail_lock)
 {
@@ -99,15 +99,15 @@ __acquires(&sdp->sd_ail_lock)
         struct gfs2_bufdata *bd, *s;
         struct buffer_head *bh;
 
-        list_for_each_entry_safe_reverse(bd, s, &ai->ai_ail1_list, bd_ail_st_list) {
+        list_for_each_entry_safe_reverse(bd, s, &tr->tr_ail1_list, bd_ail_st_list) {
                 bh = bd->bd_bh;
 
-                gfs2_assert(sdp, bd->bd_ail == ai);
+                gfs2_assert(sdp, bd->bd_tr == tr);
 
                 if (!buffer_busy(bh)) {
                         if (!buffer_uptodate(bh))
                                 gfs2_io_error_bh(sdp, bh);
-                        list_move(&bd->bd_ail_st_list, &ai->ai_ail2_list);
+                        list_move(&bd->bd_ail_st_list, &tr->tr_ail2_list);
                         continue;
                 }
 
@@ -116,7 +116,7 @@ __acquires(&sdp->sd_ail_lock)
                 if (gl == bd->bd_gl)
                         continue;
                 gl = bd->bd_gl;
-                list_move(&bd->bd_ail_st_list, &ai->ai_ail1_list);
+                list_move(&bd->bd_ail_st_list, &tr->tr_ail1_list);
                 mapping = bh->b_page->mapping;
                 if (!mapping)
                         continue;
@@ -144,15 +144,15 @@ __acquires(&sdp->sd_ail_lock)
 void gfs2_ail1_flush(struct gfs2_sbd *sdp, struct writeback_control *wbc)
 {
         struct list_head *head = &sdp->sd_ail1_list;
-        struct gfs2_ail *ai;
+        struct gfs2_trans *tr;
 
         trace_gfs2_ail_flush(sdp, wbc, 1);
         spin_lock(&sdp->sd_ail_lock);
 restart:
-        list_for_each_entry_reverse(ai, head, ai_list) {
+        list_for_each_entry_reverse(tr, head, tr_list) {
                 if (wbc->nr_to_write <= 0)
                         break;
-                if (gfs2_ail1_start_one(sdp, wbc, ai))
+                if (gfs2_ail1_start_one(sdp, wbc, tr))
                         goto restart;
         }
         spin_unlock(&sdp->sd_ail_lock);
@@ -183,20 +183,20 @@ static void gfs2_ail1_start(struct gfs2_sbd *sdp)
  *
  */
 
-static void gfs2_ail1_empty_one(struct gfs2_sbd *sdp, struct gfs2_ail *ai)
+static void gfs2_ail1_empty_one(struct gfs2_sbd *sdp, struct gfs2_trans *tr)
 {
         struct gfs2_bufdata *bd, *s;
         struct buffer_head *bh;
 
-        list_for_each_entry_safe_reverse(bd, s, &ai->ai_ail1_list,
+        list_for_each_entry_safe_reverse(bd, s, &tr->tr_ail1_list,
                                          bd_ail_st_list) {
                 bh = bd->bd_bh;
-                gfs2_assert(sdp, bd->bd_ail == ai);
+                gfs2_assert(sdp, bd->bd_tr == tr);
                 if (buffer_busy(bh))
                         continue;
                 if (!buffer_uptodate(bh))
                         gfs2_io_error_bh(sdp, bh);
-                list_move(&bd->bd_ail_st_list, &ai->ai_ail2_list);
+                list_move(&bd->bd_ail_st_list, &tr->tr_ail2_list);
         }
 
 }
@@ -210,14 +210,14 @@ static void gfs2_ail1_empty_one(struct gfs2_sbd *sdp, struct gfs2_ail *ai)
 
 static int gfs2_ail1_empty(struct gfs2_sbd *sdp)
 {
-        struct gfs2_ail *ai, *s;
+        struct gfs2_trans *tr, *s;
         int ret;
 
         spin_lock(&sdp->sd_ail_lock);
-        list_for_each_entry_safe_reverse(ai, s, &sdp->sd_ail1_list, ai_list) {
-                gfs2_ail1_empty_one(sdp, ai);
-                if (list_empty(&ai->ai_ail1_list))
-                        list_move(&ai->ai_list, &sdp->sd_ail2_list);
+        list_for_each_entry_safe_reverse(tr, s, &sdp->sd_ail1_list, tr_list) {
+                gfs2_ail1_empty_one(sdp, tr);
+                if (list_empty(&tr->tr_ail1_list))
+                        list_move(&tr->tr_list, &sdp->sd_ail2_list);
                 else
                         break;
         }
@@ -229,13 +229,13 @@ static int gfs2_ail1_empty(struct gfs2_sbd *sdp)
 
 static void gfs2_ail1_wait(struct gfs2_sbd *sdp)
 {
-        struct gfs2_ail *ai;
+        struct gfs2_trans *tr;
         struct gfs2_bufdata *bd;
         struct buffer_head *bh;
 
         spin_lock(&sdp->sd_ail_lock);
-        list_for_each_entry_reverse(ai, &sdp->sd_ail1_list, ai_list) {
-                list_for_each_entry(bd, &ai->ai_ail1_list, bd_ail_st_list) {
+        list_for_each_entry_reverse(tr, &sdp->sd_ail1_list, tr_list) {
+                list_for_each_entry(bd, &tr->tr_ail1_list, bd_ail_st_list) {
                         bh = bd->bd_bh;
                         if (!buffer_locked(bh))
                                 continue;
@@ -256,40 +256,40 @@ static void gfs2_ail1_wait(struct gfs2_sbd *sdp)
  *
  */
 
-static void gfs2_ail2_empty_one(struct gfs2_sbd *sdp, struct gfs2_ail *ai)
+static void gfs2_ail2_empty_one(struct gfs2_sbd *sdp, struct gfs2_trans *tr)
 {
-        struct list_head *head = &ai->ai_ail2_list;
+        struct list_head *head = &tr->tr_ail2_list;
         struct gfs2_bufdata *bd;
 
         while (!list_empty(head)) {
                 bd = list_entry(head->prev, struct gfs2_bufdata,
                                 bd_ail_st_list);
-                gfs2_assert(sdp, bd->bd_ail == ai);
+                gfs2_assert(sdp, bd->bd_tr == tr);
                 gfs2_remove_from_ail(bd);
         }
 }
 
 static void ail2_empty(struct gfs2_sbd *sdp, unsigned int new_tail)
 {
-        struct gfs2_ail *ai, *safe;
+        struct gfs2_trans *tr, *safe;
         unsigned int old_tail = sdp->sd_log_tail;
         int wrap = (new_tail < old_tail);
         int a, b, rm;
 
         spin_lock(&sdp->sd_ail_lock);
 
-        list_for_each_entry_safe(ai, safe, &sdp->sd_ail2_list, ai_list) {
-                a = (old_tail <= ai->ai_first);
-                b = (ai->ai_first < new_tail);
+        list_for_each_entry_safe(tr, safe, &sdp->sd_ail2_list, tr_list) {
+                a = (old_tail <= tr->tr_first);
+                b = (tr->tr_first < new_tail);
                 rm = (wrap) ? (a || b) : (a && b);
                 if (!rm)
                         continue;
 
-                gfs2_ail2_empty_one(sdp, ai);
-                list_del(&ai->ai_list);
-                gfs2_assert_warn(sdp, list_empty(&ai->ai_ail1_list));
-                gfs2_assert_warn(sdp, list_empty(&ai->ai_ail2_list));
-                kfree(ai);
+                gfs2_ail2_empty_one(sdp, tr);
+                list_del(&tr->tr_list);
+                gfs2_assert_warn(sdp, list_empty(&tr->tr_ail1_list));
+                gfs2_assert_warn(sdp, list_empty(&tr->tr_ail2_list));
+                kfree(tr);
         }
 
         spin_unlock(&sdp->sd_ail_lock);
@@ -435,7 +435,7 @@ static unsigned int calc_reserved(struct gfs2_sbd *sdp)
 
 static unsigned int current_tail(struct gfs2_sbd *sdp)
 {
-        struct gfs2_ail *ai;
+        struct gfs2_trans *tr;
         unsigned int tail;
 
         spin_lock(&sdp->sd_ail_lock);
@@ -443,8 +443,9 @@ static unsigned int current_tail(struct gfs2_sbd *sdp)
         if (list_empty(&sdp->sd_ail1_list)) {
                 tail = sdp->sd_log_head;
         } else {
-                ai = list_entry(sdp->sd_ail1_list.prev, struct gfs2_ail, ai_list);
-                tail = ai->ai_first;
+                tr = list_entry(sdp->sd_ail1_list.prev, struct gfs2_trans,
+                                tr_list);
+                tail = tr->tr_first;
         }
 
         spin_unlock(&sdp->sd_ail_lock);
@@ -600,7 +601,7 @@ static void log_write_header(struct gfs2_sbd *sdp, u32 flags)
 
 void gfs2_log_flush(struct gfs2_sbd *sdp, struct gfs2_glock *gl)
 {
-        struct gfs2_ail *ai;
+        struct gfs2_trans *tr;
 
         down_write(&sdp->sd_log_flush_lock);
 
@@ -611,9 +612,12 @@ void gfs2_log_flush(struct gfs2_sbd *sdp, struct gfs2_glock *gl)
         }
         trace_gfs2_log_flush(sdp, 1);
 
-        ai = kzalloc(sizeof(struct gfs2_ail), GFP_NOFS | __GFP_NOFAIL);
-        INIT_LIST_HEAD(&ai->ai_ail1_list);
-        INIT_LIST_HEAD(&ai->ai_ail2_list);
+        tr = sdp->sd_log_tr;
+        if (tr) {
+                sdp->sd_log_tr = NULL;
+                INIT_LIST_HEAD(&tr->tr_ail1_list);
+                INIT_LIST_HEAD(&tr->tr_ail2_list);
+        }
 
         if (sdp->sd_log_num_buf != sdp->sd_log_commited_buf) {
                 printk(KERN_INFO "GFS2: log buf %u %u\n", sdp->sd_log_num_buf,
@@ -630,7 +634,8 @@ void gfs2_log_flush(struct gfs2_sbd *sdp, struct gfs2_glock *gl)
 
         sdp->sd_log_flush_head = sdp->sd_log_head;
         sdp->sd_log_flush_wrapped = 0;
-        ai->ai_first = sdp->sd_log_flush_head;
+        if (tr)
+                tr->tr_first = sdp->sd_log_flush_head;
 
         gfs2_ordered_write(sdp);
         lops_before_commit(sdp);
@@ -643,7 +648,7 @@ void gfs2_log_flush(struct gfs2_sbd *sdp, struct gfs2_glock *gl)
                 trace_gfs2_log_blocks(sdp, -1);
                 log_write_header(sdp, 0);
         }
-        lops_after_commit(sdp, ai);
+        lops_after_commit(sdp, tr);
 
         gfs2_log_lock(sdp);
         sdp->sd_log_head = sdp->sd_log_flush_head;
@@ -653,16 +658,16 @@ void gfs2_log_flush(struct gfs2_sbd *sdp, struct gfs2_glock *gl)
         sdp->sd_log_commited_revoke = 0;
 
         spin_lock(&sdp->sd_ail_lock);
-        if (!list_empty(&ai->ai_ail1_list)) {
-                list_add(&ai->ai_list, &sdp->sd_ail1_list);
-                ai = NULL;
+        if (tr && !list_empty(&tr->tr_ail1_list)) {
+                list_add(&tr->tr_list, &sdp->sd_ail1_list);
+                tr = NULL;
         }
         spin_unlock(&sdp->sd_ail_lock);
         gfs2_log_unlock(sdp);
         trace_gfs2_log_flush(sdp, 0);
         up_write(&sdp->sd_log_flush_lock);
 
-        kfree(ai);
+        kfree(tr);
 }
 
 static void log_refund(struct gfs2_sbd *sdp, struct gfs2_trans *tr)
@@ -687,6 +692,12 @@ static void log_refund(struct gfs2_sbd *sdp, struct gfs2_trans *tr)
                              sdp->sd_jdesc->jd_blocks);
         sdp->sd_log_blks_reserved = reserved;
 
+        if (sdp->sd_log_tr == NULL &&
+            (tr->tr_num_buf_new || tr->tr_num_databuf_new)) {
+                gfs2_assert_withdraw(sdp, tr->tr_t_gh.gh_gl);
+                sdp->sd_log_tr = tr;
+                tr->tr_attached = 1;
+        }
         gfs2_log_unlock(sdp);
 }
 
@@ -708,7 +719,6 @@ static void log_refund(struct gfs2_sbd *sdp, struct gfs2_trans *tr)
 void gfs2_log_commit(struct gfs2_sbd *sdp, struct gfs2_trans *tr)
 {
         log_refund(sdp, tr);
-        up_read(&sdp->sd_log_flush_lock);
 
         if (atomic_read(&sdp->sd_log_pinned) > atomic_read(&sdp->sd_log_thresh1) ||
             ((sdp->sd_jdesc->jd_blocks - atomic_read(&sdp->sd_log_blks_free)) >