ext4: Convert ext4_lock_group to use sb_bgl_lock

We have sb_bgl_lock() and ext4_group_info.bb_state
bit spinlock to protech group information. The later is only
used within mballoc code. Consolidate them to use sb_bgl_lock().
This makes the mballoc.c code much simpler and also avoid
confusion with two locks protecting same info.

Signed-off-by: Aneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com>
Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>

5 files changed, 59 insertions, 92 deletions

diff --git a/fs/ext4/balloc.c b/fs/ext4/balloc.c
index 92f557d957d9..e2126d70dff5 100644
--- a/fs/ext4/balloc.c
+++ b/fs/ext4/balloc.c
@@ -326,16 +326,16 @@ ext4_read_block_bitmap(struct super_block *sb, ext4_group_t block_group)
                 unlock_buffer(bh);
                 return bh;
         }
-        spin_lock(sb_bgl_lock(EXT4_SB(sb), block_group));
+        ext4_lock_group(sb, block_group);
         if (desc->bg_flags & cpu_to_le16(EXT4_BG_BLOCK_UNINIT)) {
                 ext4_init_block_bitmap(sb, bh, block_group, desc);
                 set_bitmap_uptodate(bh);
                 set_buffer_uptodate(bh);
-                spin_unlock(sb_bgl_lock(EXT4_SB(sb), block_group));
+                ext4_unlock_group(sb, block_group);
                 unlock_buffer(bh);
                 return bh;
         }
-        spin_unlock(sb_bgl_lock(EXT4_SB(sb), block_group));
+        ext4_unlock_group(sb, block_group);
         if (buffer_uptodate(bh)) {
                 /*
                  * if not uninit if bh is uptodate,
@@ -451,7 +451,7 @@ void ext4_add_groupblocks(handle_t *handle, struct super_block *sb,
         down_write(&grp->alloc_sem);
         for (i = 0, blocks_freed = 0; i < count; i++) {
                 BUFFER_TRACE(bitmap_bh, "clear bit");
-                if (!ext4_clear_bit_atomic(sb_bgl_lock(sbi, block_group),
+                if (!ext4_clear_bit_atomic(ext4_group_lock_ptr(sb, block_group),
                                                 bit + i, bitmap_bh->b_data)) {
                         ext4_error(sb, __func__,
                                    "bit already cleared for block %llu",
@@ -461,11 +461,11 @@ void ext4_add_groupblocks(handle_t *handle, struct super_block *sb,
                         blocks_freed++;
                 }
         }
-        spin_lock(sb_bgl_lock(sbi, block_group));
+        ext4_lock_group(sb, block_group);
         blk_free_count = blocks_freed + ext4_free_blks_count(sb, desc);
         ext4_free_blks_set(sb, desc, blk_free_count);
         desc->bg_checksum = ext4_group_desc_csum(sbi, block_group, desc);
-        spin_unlock(sb_bgl_lock(sbi, block_group));
+        ext4_unlock_group(sb, block_group);
         percpu_counter_add(&sbi->s_freeblocks_counter, blocks_freed);
 
         if (sbi->s_log_groups_per_flex) {
diff --git a/fs/ext4/ext4.h b/fs/ext4/ext4.h
index 5973f3261b0c..149e02dc3606 100644
--- a/fs/ext4/ext4.h
+++ b/fs/ext4/ext4.h
@@ -963,12 +963,6 @@ static inline int ext4_valid_inum(struct super_block *sb, unsigned long ino)
                 (ino >= EXT4_FIRST_INO(sb) &&
                  ino <= le32_to_cpu(EXT4_SB(sb)->s_es->s_inodes_count));
 }
-
-static inline spinlock_t *
-sb_bgl_lock(struct ext4_sb_info *sbi, unsigned int block_group)
-{
-        return bgl_lock_ptr(sbi->s_blockgroup_lock, block_group);
-}
 #else
 /* Assume that user mode programs are passing in an ext4fs superblock, not
  * a kernel struct super_block.  This will allow us to call the feature-test
@@ -1568,33 +1562,31 @@ struct ext4_group_info {
 };
 
 #define EXT4_GROUP_INFO_NEED_INIT_BIT   0
-#define EXT4_GROUP_INFO_LOCKED_BIT      1
 
 #define EXT4_MB_GRP_NEED_INIT(grp)      \
         (test_bit(EXT4_GROUP_INFO_NEED_INIT_BIT, &((grp)->bb_state)))
 
-static inline void ext4_lock_group(struct super_block *sb, ext4_group_t group)
+static inline spinlock_t *ext4_group_lock_ptr(struct super_block *sb,
+                                              ext4_group_t group)
 {
-        struct ext4_group_info *grinfo = ext4_get_group_info(sb, group);
+        return bgl_lock_ptr(EXT4_SB(sb)->s_blockgroup_lock, group);
+}
 
-        bit_spin_lock(EXT4_GROUP_INFO_LOCKED_BIT, &(grinfo->bb_state));
+static inline void ext4_lock_group(struct super_block *sb, ext4_group_t group)
+{
+        spin_lock(ext4_group_lock_ptr(sb, group));
 }
 
 static inline void ext4_unlock_group(struct super_block *sb,
                                         ext4_group_t group)
 {
-        struct ext4_group_info *grinfo = ext4_get_group_info(sb, group);
-
-        bit_spin_unlock(EXT4_GROUP_INFO_LOCKED_BIT, &(grinfo->bb_state));
+        spin_unlock(ext4_group_lock_ptr(sb, group));
 }
 
 static inline int ext4_is_group_locked(struct super_block *sb,
                                         ext4_group_t group)
 {
-        struct ext4_group_info *grinfo = ext4_get_group_info(sb, group);
-
-        return bit_spin_is_locked(EXT4_GROUP_INFO_LOCKED_BIT,
-                                                &(grinfo->bb_state));
+        return spin_is_locked(ext4_group_lock_ptr(sb, group));
 }
 
 /*
diff --git a/fs/ext4/ialloc.c b/fs/ext4/ialloc.c
index 916d05c881ca..82f7d1d7eae0 100644
--- a/fs/ext4/ialloc.c
+++ b/fs/ext4/ialloc.c
@@ -122,16 +122,16 @@ ext4_read_inode_bitmap(struct super_block *sb, ext4_group_t block_group)
                 unlock_buffer(bh);
                 return bh;
         }
-        spin_lock(sb_bgl_lock(EXT4_SB(sb), block_group));
+        ext4_lock_group(sb, block_group);
         if (desc->bg_flags & cpu_to_le16(EXT4_BG_INODE_UNINIT)) {
                 ext4_init_inode_bitmap(sb, bh, block_group, desc);
                 set_bitmap_uptodate(bh);
                 set_buffer_uptodate(bh);
-                spin_unlock(sb_bgl_lock(EXT4_SB(sb), block_group));
+                ext4_unlock_group(sb, block_group);
                 unlock_buffer(bh);
                 return bh;
         }
-        spin_unlock(sb_bgl_lock(EXT4_SB(sb), block_group));
+        ext4_unlock_group(sb, block_group);
         if (buffer_uptodate(bh)) {
                 /*
                  * if not uninit if bh is uptodate,
@@ -246,9 +246,8 @@ void ext4_free_inode(handle_t *handle, struct inode *inode)
                 goto error_return;
 
         /* Ok, now we can actually update the inode bitmaps.. */
-        spin_lock(sb_bgl_lock(sbi, block_group));
-        cleared = ext4_clear_bit(bit, bitmap_bh->b_data);
-        spin_unlock(sb_bgl_lock(sbi, block_group));
+        cleared = ext4_clear_bit_atomic(ext4_group_lock_ptr(sb, block_group),
+                                        bit, bitmap_bh->b_data);
         if (!cleared)
                 ext4_error(sb, "ext4_free_inode",
                            "bit already cleared for inode %lu", ino);
@@ -260,7 +259,7 @@ void ext4_free_inode(handle_t *handle, struct inode *inode)
                 if (fatal) goto error_return;
 
                 if (gdp) {
-                        spin_lock(sb_bgl_lock(sbi, block_group));
+                        ext4_lock_group(sb, block_group);
                         count = ext4_free_inodes_count(sb, gdp) + 1;
                         ext4_free_inodes_set(sb, gdp, count);
                         if (is_directory) {
@@ -276,7 +275,7 @@ void ext4_free_inode(handle_t *handle, struct inode *inode)
                         }
                         gdp->bg_checksum = ext4_group_desc_csum(sbi,
                                                         block_group, gdp);
-                        spin_unlock(sb_bgl_lock(sbi, block_group));
+                        ext4_unlock_group(sb, block_group);
                         percpu_counter_inc(&sbi->s_freeinodes_counter);
                         if (is_directory)
                                 percpu_counter_dec(&sbi->s_dirs_counter);
@@ -707,10 +706,10 @@ static int find_group_other(struct super_block *sb, struct inode *parent,
 
 /*
  * claim the inode from the inode bitmap. If the group
- * is uninit we need to take the groups's sb_bgl_lock
+ * is uninit we need to take the groups's ext4_group_lock
  * and clear the uninit flag. The inode bitmap update
  * and group desc uninit flag clear should be done
- * after holding sb_bgl_lock so that ext4_read_inode_bitmap
+ * after holding ext4_group_lock so that ext4_read_inode_bitmap
  * doesn't race with the ext4_claim_inode
  */
 static int ext4_claim_inode(struct super_block *sb,
@@ -721,7 +720,7 @@ static int ext4_claim_inode(struct super_block *sb,
         struct ext4_sb_info *sbi = EXT4_SB(sb);
         struct ext4_group_desc *gdp = ext4_get_group_desc(sb, group, NULL);
 
-        spin_lock(sb_bgl_lock(sbi, group));
+        ext4_lock_group(sb, group);
         if (ext4_set_bit(ino, inode_bitmap_bh->b_data)) {
                 /* not a free inode */
                 retval = 1;
@@ -730,7 +729,7 @@ static int ext4_claim_inode(struct super_block *sb,
         ino++;
         if ((group == 0 && ino < EXT4_FIRST_INO(sb)) ||
                         ino > EXT4_INODES_PER_GROUP(sb)) {
-                spin_unlock(sb_bgl_lock(sbi, group));
+                ext4_unlock_group(sb, group);
                 ext4_error(sb, __func__,
                            "reserved inode or inode > inodes count - "
                            "block_group = %u, inode=%lu", group,
@@ -779,7 +778,7 @@ static int ext4_claim_inode(struct super_block *sb,
         }
         gdp->bg_checksum = ext4_group_desc_csum(sbi, group, gdp);
 err_ret:
-        spin_unlock(sb_bgl_lock(sbi, group));
+        ext4_unlock_group(sb, group);
         return retval;
 }
 
@@ -935,7 +934,7 @@ got:
                 }
 
                 free = 0;
-                spin_lock(sb_bgl_lock(sbi, group));
+                ext4_lock_group(sb, group);
                 /* recheck and clear flag under lock if we still need to */
                 if (gdp->bg_flags & cpu_to_le16(EXT4_BG_BLOCK_UNINIT)) {
                         free = ext4_free_blocks_after_init(sb, group, gdp);
@@ -944,7 +943,7 @@ got:
                         gdp->bg_checksum = ext4_group_desc_csum(sbi, group,
                                                                 gdp);
                 }
-                spin_unlock(sb_bgl_lock(sbi, group));
+                ext4_unlock_group(sb, group);
 
                 /* Don't need to dirty bitmap block if we didn't change it */
                 if (free) {
diff --git a/fs/ext4/mballoc.c b/fs/ext4/mballoc.c
index df75855ae6f7..e76459cedcdb 100644
--- a/fs/ext4/mballoc.c
+++ b/fs/ext4/mballoc.c
@@ -372,24 +372,12 @@ static inline void mb_set_bit(int bit, void *addr)
         ext4_set_bit(bit, addr);
 }
 
-static inline void mb_set_bit_atomic(spinlock_t *lock, int bit, void *addr)
-{
-        addr = mb_correct_addr_and_bit(&bit, addr);
-        ext4_set_bit_atomic(lock, bit, addr);
-}
-
 static inline void mb_clear_bit(int bit, void *addr)
 {
         addr = mb_correct_addr_and_bit(&bit, addr);
         ext4_clear_bit(bit, addr);
 }
 
-static inline void mb_clear_bit_atomic(spinlock_t *lock, int bit, void *addr)
-{
-        addr = mb_correct_addr_and_bit(&bit, addr);
-        ext4_clear_bit_atomic(lock, bit, addr);
-}
-
 static inline int mb_find_next_zero_bit(void *addr, int max, int start)
 {
         int fix = 0, ret, tmpmax;
@@ -803,17 +791,17 @@ static int ext4_mb_init_cache(struct page *page, char *incore)
                         unlock_buffer(bh[i]);
                         continue;
                 }
-                spin_lock(sb_bgl_lock(EXT4_SB(sb), first_group + i));
+                ext4_lock_group(sb, first_group + i);
                 if (desc->bg_flags & cpu_to_le16(EXT4_BG_BLOCK_UNINIT)) {
                         ext4_init_block_bitmap(sb, bh[i],
                                                 first_group + i, desc);
                         set_bitmap_uptodate(bh[i]);
                         set_buffer_uptodate(bh[i]);
-                        spin_unlock(sb_bgl_lock(EXT4_SB(sb), first_group + i));
+                        ext4_unlock_group(sb, first_group + i);
                         unlock_buffer(bh[i]);
                         continue;
                 }
-                spin_unlock(sb_bgl_lock(EXT4_SB(sb), first_group + i));
+                ext4_unlock_group(sb, first_group + i);
                 if (buffer_uptodate(bh[i])) {
                         /*
                          * if not uninit if bh is uptodate,
@@ -1080,7 +1068,7 @@ static int mb_find_order_for_block(struct ext4_buddy *e4b, int block)
         return 0;
 }
 
-static void mb_clear_bits(spinlock_t *lock, void *bm, int cur, int len)
+static void mb_clear_bits(void *bm, int cur, int len)
 {
         __u32 *addr;
 
@@ -1093,15 +1081,12 @@ static void mb_clear_bits(spinlock_t *lock, void *bm, int cur, int len)
                         cur += 32;
                         continue;
                 }
-                if (lock)
-                        mb_clear_bit_atomic(lock, cur, bm);
-                else
-                        mb_clear_bit(cur, bm);
+                mb_clear_bit(cur, bm);
                 cur++;
         }
 }
 
-static void mb_set_bits(spinlock_t *lock, void *bm, int cur, int len)
+static void mb_set_bits(void *bm, int cur, int len)
 {
         __u32 *addr;
 
@@ -1114,10 +1099,7 @@ static void mb_set_bits(spinlock_t *lock, void *bm, int cur, int len)
                         cur += 32;
                         continue;
                 }
-                if (lock)
-                        mb_set_bit_atomic(lock, cur, bm);
-                else
-                        mb_set_bit(cur, bm);
+                mb_set_bit(cur, bm);
                 cur++;
         }
 }
@@ -1332,8 +1314,7 @@ static int mb_mark_used(struct ext4_buddy *e4b, struct ext4_free_extent *ex)
                 e4b->bd_info->bb_counters[ord]++;
         }
 
-        mb_set_bits(sb_bgl_lock(EXT4_SB(e4b->bd_sb), ex->fe_group),
-                        EXT4_MB_BITMAP(e4b), ex->fe_start, len0);
+        mb_set_bits(EXT4_MB_BITMAP(e4b), ex->fe_start, len0);
         mb_check_buddy(e4b);
 
         return ret;
@@ -2756,7 +2737,7 @@ int ext4_mb_init(struct super_block *sb, int needs_recovery)
         return 0;
 }
 
-/* need to called with ext4 group lock (ext4_lock_group) */
+/* need to called with the ext4 group lock held */
 static void ext4_mb_cleanup_pa(struct ext4_group_info *grp)
 {
         struct ext4_prealloc_space *pa;
@@ -2993,14 +2974,17 @@ ext4_mb_mark_diskspace_used(struct ext4_allocation_context *ac,
                  * Fix the bitmap and repeat the block allocation
                  * We leak some of the blocks here.
                  */
-                mb_set_bits(sb_bgl_lock(sbi, ac->ac_b_ex.fe_group),
-                                bitmap_bh->b_data, ac->ac_b_ex.fe_start,
-                                ac->ac_b_ex.fe_len);
+                ext4_lock_group(sb, ac->ac_b_ex.fe_group);
+                mb_set_bits(bitmap_bh->b_data, ac->ac_b_ex.fe_start,
+                            ac->ac_b_ex.fe_len);
+                ext4_unlock_group(sb, ac->ac_b_ex.fe_group);
                 err = ext4_handle_dirty_metadata(handle, NULL, bitmap_bh);
                 if (!err)
                         err = -EAGAIN;
                 goto out_err;
         }
+
+        ext4_lock_group(sb, ac->ac_b_ex.fe_group);
 #ifdef AGGRESSIVE_CHECK
         {
                 int i;
@@ -3010,9 +2994,7 @@ ext4_mb_mark_diskspace_used(struct ext4_allocation_context *ac,
                 }
         }
 #endif
-        spin_lock(sb_bgl_lock(sbi, ac->ac_b_ex.fe_group));
-        mb_set_bits(NULL, bitmap_bh->b_data,
-                                ac->ac_b_ex.fe_start, ac->ac_b_ex.fe_len);
+        mb_set_bits(bitmap_bh->b_data, ac->ac_b_ex.fe_start,ac->ac_b_ex.fe_len);
         if (gdp->bg_flags & cpu_to_le16(EXT4_BG_BLOCK_UNINIT)) {
                 gdp->bg_flags &= cpu_to_le16(~EXT4_BG_BLOCK_UNINIT);
                 ext4_free_blks_set(sb, gdp,
@@ -3022,7 +3004,8 @@ ext4_mb_mark_diskspace_used(struct ext4_allocation_context *ac,
         len = ext4_free_blks_count(sb, gdp) - ac->ac_b_ex.fe_len;
         ext4_free_blks_set(sb, gdp, len);
         gdp->bg_checksum = ext4_group_desc_csum(sbi, ac->ac_b_ex.fe_group, gdp);
-        spin_unlock(sb_bgl_lock(sbi, ac->ac_b_ex.fe_group));
+
+        ext4_unlock_group(sb, ac->ac_b_ex.fe_group);
         percpu_counter_sub(&sbi->s_freeblocks_counter, ac->ac_b_ex.fe_len);
         /*
          * Now reduce the dirty block count also. Should not go negative
@@ -3455,7 +3438,7 @@ ext4_mb_use_preallocated(struct ext4_allocation_context *ac)
  * the function goes through all block freed in the group
  * but not yet committed and marks them used in in-core bitmap.
  * buddy must be generated from this bitmap
- * Need to be called with ext4 group lock (ext4_lock_group)
+ * Need to be called with the ext4 group lock held
  */
 static void ext4_mb_generate_from_freelist(struct super_block *sb, void *bitmap,
                                                 ext4_group_t group)
@@ -3469,9 +3452,7 @@ static void ext4_mb_generate_from_freelist(struct super_block *sb, void *bitmap,
 
         while (n) {
                 entry = rb_entry(n, struct ext4_free_data, node);
-                mb_set_bits(sb_bgl_lock(EXT4_SB(sb), group),
-                                bitmap, entry->start_blk,
-                                entry->count);
+                mb_set_bits(bitmap, entry->start_blk, entry->count);
                 n = rb_next(n);
         }
         return;
@@ -3480,7 +3461,7 @@ static void ext4_mb_generate_from_freelist(struct super_block *sb, void *bitmap,
 /*
  * the function goes through all preallocation in this group and marks them
  * used in in-core bitmap. buddy must be generated from this bitmap
- * Need to be called with ext4 group lock (ext4_lock_group)
+ * Need to be called with ext4 group lock held
  */
 static void ext4_mb_generate_from_pa(struct super_block *sb, void *bitmap,
                                         ext4_group_t group)
@@ -3512,8 +3493,7 @@ static void ext4_mb_generate_from_pa(struct super_block *sb, void *bitmap,
                 if (unlikely(len == 0))
                         continue;
                 BUG_ON(groupnr != group);
-                mb_set_bits(sb_bgl_lock(EXT4_SB(sb), group),
-                                                bitmap, start, len);
+                mb_set_bits(bitmap, start, len);
                 preallocated += len;
                 count++;
         }
@@ -4856,29 +4836,25 @@ do_more:
                 new_entry->group  = block_group;
                 new_entry->count = count;
                 new_entry->t_tid = handle->h_transaction->t_tid;
+
                 ext4_lock_group(sb, block_group);
-                mb_clear_bits(sb_bgl_lock(sbi, block_group), bitmap_bh->b_data,
-                                bit, count);
+                mb_clear_bits(bitmap_bh->b_data, bit, count);
                 ext4_mb_free_metadata(handle, &e4b, new_entry);
-                ext4_unlock_group(sb, block_group);
         } else {
-                ext4_lock_group(sb, block_group);
                 /* need to update group_info->bb_free and bitmap
                  * with group lock held. generate_buddy look at
                  * them with group lock_held
                  */
-                mb_clear_bits(sb_bgl_lock(sbi, block_group), bitmap_bh->b_data,
-                                bit, count);
+                ext4_lock_group(sb, block_group);
+                mb_clear_bits(bitmap_bh->b_data, bit, count);
                 mb_free_blocks(inode, &e4b, bit, count);
                 ext4_mb_return_to_preallocation(inode, &e4b, block, count);
-                ext4_unlock_group(sb, block_group);
         }
 
-        spin_lock(sb_bgl_lock(sbi, block_group));
         ret = ext4_free_blks_count(sb, gdp) + count;
         ext4_free_blks_set(sb, gdp, ret);
         gdp->bg_checksum = ext4_group_desc_csum(sbi, block_group, gdp);
-        spin_unlock(sb_bgl_lock(sbi, block_group));
+        ext4_unlock_group(sb, block_group);
         percpu_counter_add(&sbi->s_freeblocks_counter, count);
 
         if (sbi->s_log_groups_per_flex) {
diff --git a/fs/ext4/super.c b/fs/ext4/super.c
index 39223a52bc71..dc34ed3d1327 100644
--- a/fs/ext4/super.c
+++ b/fs/ext4/super.c
@@ -1784,18 +1784,18 @@ static int ext4_check_descriptors(struct super_block *sb)
                                "(block %llu)!\n", i, inode_table);
                         return 0;
                 }
-                spin_lock(sb_bgl_lock(sbi, i));
+                ext4_lock_group(sb, i);
                 if (!ext4_group_desc_csum_verify(sbi, i, gdp)) {
                         printk(KERN_ERR "EXT4-fs: ext4_check_descriptors: "
                                "Checksum for group %u failed (%u!=%u)\n",
                                i, le16_to_cpu(ext4_group_desc_csum(sbi, i,
                                gdp)), le16_to_cpu(gdp->bg_checksum));
                         if (!(sb->s_flags & MS_RDONLY)) {
-                                spin_unlock(sb_bgl_lock(sbi, i));
+                                ext4_unlock_group(sb, i);
                                 return 0;
                         }
                 }
-                spin_unlock(sb_bgl_lock(sbi, i));
+                ext4_unlock_group(sb, i);
                 if (!flexbg_flag)
                         first_block += EXT4_BLOCKS_PER_GROUP(sb);
         }