[GFS2] Clean up journaled data writing

This patch cleans up the code for writing journaled data into the log.
It also removes the need to allocate a small "tag" structure for each
block written into the log. Instead we just keep count of the outstanding
I/O so that we can be sure that its all been written at the correct time.
Another result of this patch is that a number of ll_rw_block() calls
have become submit_bh() calls, closing some races at the same time.

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

1 files changed, 126 insertions, 116 deletions

diff --git a/fs/gfs2/lops.c b/fs/gfs2/lops.c
index 342c10e12af2..6c27cea761c6 100644
--- a/fs/gfs2/lops.c
+++ b/fs/gfs2/lops.c
@@ -91,6 +91,39 @@ static void gfs2_unpin(struct gfs2_sbd *sdp, struct buffer_head *bh,
         unlock_buffer(bh);
 }
 
+
+static inline struct gfs2_log_descriptor *bh_log_desc(struct buffer_head *bh)
+{
+        return (struct gfs2_log_descriptor *)bh->b_data;
+}
+
+static inline __be64 *bh_log_ptr(struct buffer_head *bh)
+{
+        struct gfs2_log_descriptor *ld = bh_log_desc(bh);
+        return (__force __be64 *)(ld + 1);
+}
+
+static inline __be64 *bh_ptr_end(struct buffer_head *bh)
+{
+        return (__force __be64 *)(bh->b_data + bh->b_size);
+}
+
+
+static struct buffer_head *gfs2_get_log_desc(struct gfs2_sbd *sdp, u32 ld_type)
+{
+        struct buffer_head *bh = gfs2_log_get_buf(sdp);
+        struct gfs2_log_descriptor *ld = bh_log_desc(bh);
+        ld->ld_header.mh_magic = cpu_to_be32(GFS2_MAGIC);
+        ld->ld_header.mh_type = cpu_to_be32(GFS2_METATYPE_LD);
+        ld->ld_header.mh_format = cpu_to_be32(GFS2_FORMAT_LD);
+        ld->ld_type = cpu_to_be32(ld_type);
+        ld->ld_length = 0;
+        ld->ld_data1 = 0;
+        ld->ld_data2 = 0;
+        memset(ld->ld_reserved, 0, sizeof(ld->ld_reserved));
+        return bh;
+}
+
 static void __glock_lo_add(struct gfs2_sbd *sdp, struct gfs2_log_element *le)
 {
         struct gfs2_glock *gl;
@@ -181,7 +214,6 @@ static void buf_lo_before_commit(struct gfs2_sbd *sdp)
         struct gfs2_log_descriptor *ld;
         struct gfs2_bufdata *bd1 = NULL, *bd2;
         unsigned int total;
-        unsigned int offset = BUF_OFFSET;
         unsigned int limit;
         unsigned int num;
         unsigned n;
@@ -198,18 +230,12 @@ static void buf_lo_before_commit(struct gfs2_sbd *sdp)
                 if (total > limit)
                         num = limit;
                 gfs2_log_unlock(sdp);
-                bh = gfs2_log_get_buf(sdp);
+                bh = gfs2_get_log_desc(sdp, GFS2_LOG_DESC_METADATA);
                 gfs2_log_lock(sdp);
-                ld = (struct gfs2_log_descriptor *)bh->b_data;
-                ptr = (__be64 *)(bh->b_data + offset);
-                ld->ld_header.mh_magic = cpu_to_be32(GFS2_MAGIC);
-                ld->ld_header.mh_type = cpu_to_be32(GFS2_METATYPE_LD);
-                ld->ld_header.mh_format = cpu_to_be32(GFS2_FORMAT_LD);
-                ld->ld_type = cpu_to_be32(GFS2_LOG_DESC_METADATA);
+                ld = bh_log_desc(bh);
+                ptr = bh_log_ptr(bh);
                 ld->ld_length = cpu_to_be32(num + 1);
                 ld->ld_data1 = cpu_to_be32(num);
-                ld->ld_data2 = cpu_to_be32(0);
-                memset(ld->ld_reserved, 0, sizeof(ld->ld_reserved));
 
                 n = 0;
                 list_for_each_entry_continue(bd1, &sdp->sd_log_le_buf,
@@ -220,17 +246,17 @@ static void buf_lo_before_commit(struct gfs2_sbd *sdp)
                 }
 
                 gfs2_log_unlock(sdp);
-                set_buffer_dirty(bh);
-                ll_rw_block(WRITE, 1, &bh);
+                submit_bh(WRITE, bh);
                 gfs2_log_lock(sdp);
 
                 n = 0;
                 list_for_each_entry_continue(bd2, &sdp->sd_log_le_buf,
                                              bd_le.le_list) {
+                        get_bh(bd2->bd_bh);
                         gfs2_log_unlock(sdp);
+                        lock_buffer(bd2->bd_bh);
                         bh = gfs2_log_fake_buf(sdp, bd2->bd_bh);
-                        set_buffer_dirty(bh);
-                        ll_rw_block(WRITE, 1, &bh);
+                        submit_bh(WRITE, bh);
                         gfs2_log_lock(sdp);
                         if (++n >= num)
                                 break;
@@ -359,17 +385,11 @@ static void revoke_lo_before_commit(struct gfs2_sbd *sdp)
         if (!sdp->sd_log_num_revoke)
                 return;
 
-        bh = gfs2_log_get_buf(sdp);
-        ld = (struct gfs2_log_descriptor *)bh->b_data;
-        ld->ld_header.mh_magic = cpu_to_be32(GFS2_MAGIC);
-        ld->ld_header.mh_type = cpu_to_be32(GFS2_METATYPE_LD);
-        ld->ld_header.mh_format = cpu_to_be32(GFS2_FORMAT_LD);
-        ld->ld_type = cpu_to_be32(GFS2_LOG_DESC_REVOKE);
+        bh = gfs2_get_log_desc(sdp, GFS2_LOG_DESC_REVOKE);
+        ld = bh_log_desc(bh);
         ld->ld_length = cpu_to_be32(gfs2_struct2blk(sdp, sdp->sd_log_num_revoke,
                                                     sizeof(u64)));
         ld->ld_data1 = cpu_to_be32(sdp->sd_log_num_revoke);
-        ld->ld_data2 = cpu_to_be32(0);
-        memset(ld->ld_reserved, 0, sizeof(ld->ld_reserved));
         offset = sizeof(struct gfs2_log_descriptor);
 
         while (!list_empty(head)) {
@@ -378,8 +398,7 @@ static void revoke_lo_before_commit(struct gfs2_sbd *sdp)
                 sdp->sd_log_num_revoke--;
 
                 if (offset + sizeof(u64) > sdp->sd_sb.sb_bsize) {
-                        set_buffer_dirty(bh);
-                        ll_rw_block(WRITE, 1, &bh);
+                        submit_bh(WRITE, bh);
 
                         bh = gfs2_log_get_buf(sdp);
                         mh = (struct gfs2_meta_header *)bh->b_data;
@@ -396,8 +415,7 @@ static void revoke_lo_before_commit(struct gfs2_sbd *sdp)
         }
         gfs2_assert_withdraw(sdp, !sdp->sd_log_num_revoke);
 
-        set_buffer_dirty(bh);
-        ll_rw_block(WRITE, 1, &bh);
+        submit_bh(WRITE, bh);
 }
 
 static void revoke_lo_before_scan(struct gfs2_jdesc *jd,
@@ -562,118 +580,110 @@ out:
         unlock_buffer(bd->bd_bh);
 }
 
-static int gfs2_check_magic(struct buffer_head *bh)
+static void gfs2_check_magic(struct buffer_head *bh)
 {
-        struct page *page = bh->b_page;
         void *kaddr;
         __be32 *ptr;
-        int rv = 0;
 
-        kaddr = kmap_atomic(page, KM_USER0);
+        clear_buffer_escaped(bh);
+        kaddr = kmap_atomic(bh->b_page, KM_USER0);
         ptr = kaddr + bh_offset(bh);
         if (*ptr == cpu_to_be32(GFS2_MAGIC))
-                rv = 1;
+                set_buffer_escaped(bh);
         kunmap_atomic(kaddr, KM_USER0);
-
-        return rv;
 }
 
-/**
- * databuf_lo_before_commit - Scan the data buffers, writing as we go
- *
- */
-
-static void databuf_lo_before_commit(struct gfs2_sbd *sdp)
+static void gfs2_write_blocks(struct gfs2_sbd *sdp, struct buffer_head *bh,
+                              struct list_head *list, struct list_head *done,
+                              unsigned int n)
 {
-        struct gfs2_bufdata *bd1 = NULL, *bd2;
-        struct buffer_head *bh = NULL,*bh1 = NULL;
+        struct buffer_head *bh1;
         struct gfs2_log_descriptor *ld;
-        unsigned int limit;
-        unsigned int total;
-        unsigned int num, n;
-        __be64 *ptr = NULL;
-        int magic;
+        struct gfs2_bufdata *bd;
+        __be64 *ptr;
 
+        if (!bh)
+                return;
 
-        limit = databuf_limit(sdp);
+        ld = bh_log_desc(bh);
+        ld->ld_length = cpu_to_be32(n + 1);
+        ld->ld_data1 = cpu_to_be32(n);
 
+        ptr = bh_log_ptr(bh);
+        
+        get_bh(bh);
+        submit_bh(WRITE, bh);
         gfs2_log_lock(sdp);
-        total = sdp->sd_log_num_databuf;
-        bd2 = bd1 = list_prepare_entry(bd1, &sdp->sd_log_le_databuf,
-                                       bd_le.le_list);
-        while(total) {
-                num = total;
-                if (num > limit)
-                        num = limit;
-
-                gfs2_log_unlock(sdp);
-                bh = gfs2_log_get_buf(sdp);
-                gfs2_log_lock(sdp);
-
-                ld = (struct gfs2_log_descriptor *)bh->b_data;
-                ptr = (__be64 *)(bh->b_data + DATABUF_OFFSET);
-                ld->ld_header.mh_magic = cpu_to_be32(GFS2_MAGIC);
-                ld->ld_header.mh_type = cpu_to_be32(GFS2_METATYPE_LD);
-                ld->ld_header.mh_format = cpu_to_be32(GFS2_FORMAT_LD);
-                ld->ld_type = cpu_to_be32(GFS2_LOG_DESC_JDATA);
-                ld->ld_length = cpu_to_be32(num + 1);
-                ld->ld_data1 = cpu_to_be32(num);
-                ld->ld_data2 = cpu_to_be32(0);
-                memset(ld->ld_reserved, 0, sizeof(ld->ld_reserved));
-
-                n = 0;
-                list_for_each_entry_continue(bd1, &sdp->sd_log_le_databuf,
-                                             bd_le.le_list) {
-                        bh1 = bd1->bd_bh;
-
-                        magic = gfs2_check_magic(bh1);
-                        *ptr++ = cpu_to_be64(bh1->b_blocknr);
-                        *ptr++ = cpu_to_be64((__u64)magic);
-                        clear_buffer_escaped(bh1);
-                        if (unlikely(magic != 0))
-                                set_buffer_escaped(bh1);
-                        if (++n >= num)
-                                break;
+        while(!list_empty(list)) {
+                bd = list_entry(list->next, struct gfs2_bufdata, bd_le.le_list);
+                list_move_tail(&bd->bd_le.le_list, done);
+                get_bh(bd->bd_bh);
+                while (be64_to_cpu(*ptr) != bd->bd_bh->b_blocknr) {
+                        gfs2_log_incr_head(sdp);
+                        ptr += 2;
                 }
                 gfs2_log_unlock(sdp);
-                if (bh) {
-                        set_buffer_dirty(bh);
-                        ll_rw_block(WRITE, 1, &bh);
-                        bh = NULL;
-                        ptr = NULL;
+                lock_buffer(bd->bd_bh);
+                if (buffer_escaped(bd->bd_bh)) {
+                        void *kaddr;
+                        bh1 = gfs2_log_get_buf(sdp);
+                        kaddr = kmap_atomic(bd->bd_bh->b_page, KM_USER0);
+                        memcpy(bh1->b_data, kaddr + bh_offset(bd->bd_bh),
+                               bh1->b_size);
+                        kunmap_atomic(kaddr, KM_USER0);
+                        *(__be32 *)bh1->b_data = 0;
+                        clear_buffer_escaped(bd->bd_bh);
+                        unlock_buffer(bd->bd_bh);
+                        brelse(bd->bd_bh);
+                } else {
+                        bh1 = gfs2_log_fake_buf(sdp, bd->bd_bh);
                 }
-                n = 0;
+                submit_bh(WRITE, bh1);
                 gfs2_log_lock(sdp);
-                list_for_each_entry_continue(bd2, &sdp->sd_log_le_databuf,
-                                             bd_le.le_list) {
-                        if (!bd2->bd_bh)
-                                continue;
-                        /* copy buffer if it needs escaping */
+                ptr += 2;
+        }
+        gfs2_log_unlock(sdp);
+        brelse(bh);
+}
+
+/**
+ * databuf_lo_before_commit - Scan the data buffers, writing as we go
+ *
+ */
+
+static void databuf_lo_before_commit(struct gfs2_sbd *sdp)
+{
+        struct gfs2_bufdata *bd = NULL;
+        struct buffer_head *bh = NULL;
+        unsigned int n = 0;
+        __be64 *ptr = NULL, *end = NULL;
+        LIST_HEAD(processed);
+        LIST_HEAD(in_progress);
+
+        gfs2_log_lock(sdp);
+        while (!list_empty(&sdp->sd_log_le_databuf)) {
+                if (ptr == end) {
                         gfs2_log_unlock(sdp);
-                        if (unlikely(buffer_escaped(bd2->bd_bh))) {
-                                void *kaddr;
-                                struct page *page = bd2->bd_bh->b_page;
-                                bh = gfs2_log_get_buf(sdp);
-                                kaddr = kmap_atomic(page, KM_USER0);
-                                memcpy(bh->b_data,
-                                       kaddr + bh_offset(bd2->bd_bh),
-                                       sdp->sd_sb.sb_bsize);
-                                kunmap_atomic(kaddr, KM_USER0);
-                                *(__be32 *)bh->b_data = 0;
-                        } else {
-                                bh = gfs2_log_fake_buf(sdp, bd2->bd_bh);
-                        }
-                        set_buffer_dirty(bh);
-                        ll_rw_block(WRITE, 1, &bh);
+                        gfs2_write_blocks(sdp, bh, &in_progress, &processed, n);
+                        n = 0;
+                        bh = gfs2_get_log_desc(sdp, GFS2_LOG_DESC_JDATA);
+                        ptr = bh_log_ptr(bh);
+                        end = bh_ptr_end(bh) - 1;
                         gfs2_log_lock(sdp);
-                        if (++n >= num)
-                                break;
+                        continue;
                 }
-                bh = NULL;
-                BUG_ON(total < num);
-                total -= num;
+                bd = list_entry(sdp->sd_log_le_databuf.next, struct gfs2_bufdata, bd_le.le_list);
+                list_move_tail(&bd->bd_le.le_list, &in_progress);
+                gfs2_check_magic(bd->bd_bh);
+                *ptr++ = cpu_to_be64(bd->bd_bh->b_blocknr);
+                *ptr++ = cpu_to_be64(buffer_escaped(bh) ? 1 : 0);
+                n++;
         }
         gfs2_log_unlock(sdp);
+        gfs2_write_blocks(sdp, bh, &in_progress, &processed, n);
+        gfs2_log_lock(sdp);
+        list_splice(&processed, &sdp->sd_log_le_databuf);
+        gfs2_log_unlock(sdp);
 }
 
 static int databuf_lo_scan_elements(struct gfs2_jdesc *jd, unsigned int start,
@@ -807,10 +817,10 @@ const struct gfs2_log_operations gfs2_databuf_lops = {
 
 const struct gfs2_log_operations *gfs2_log_ops[] = {
         &gfs2_glock_lops,
+        &gfs2_databuf_lops,
         &gfs2_buf_lops,
-        &gfs2_revoke_lops,
         &gfs2_rg_lops,
-        &gfs2_databuf_lops,
+        &gfs2_revoke_lops,
         NULL,
 };