[PATCH v3 14/19] ext4: extent ext4_mb_mark_group_bb to support allocation under journal

[Kemeng Shi]

Previously, ext4_mb_mark_group_bb is only called under fast commit
replay path, so there is no valid handle when we update block bitmap
and group descriptor. This patch try to extent ext4_mb_mark_group_bb
to be used by code under journal. There are several improves:
1. add "handle_t *handle" to struct ext4_mark_context to accept handle
to journal block bitmap and group descriptor update inside
ext4_mb_mark_group_bb (the added journal caode is based on journal
code in ext4_mb_mark_diskspace_used where ext4_mb_mark_group_bb
is going to be used.)
2. add EXT4_MB_BITMAP_MARKED_CHECK flag to control check if bits in block
bitmap are already marked as allocation code under journal asserts that
all bits to be changed are not marked before.
3. add "ext4_grpblk_t changed" to struct ext4_mark_context to notify number
of bits in block bitmap has changed.

Signed-off-by: Kemeng Shi <shikemeng@xxxxxxxxxxxxxxx>
---
 fs/ext4/mballoc.c | 59 ++++++++++++++++++++++++++++++++++++-----------
 1 file changed, 45 insertions(+), 14 deletions(-)

diff --git a/fs/ext4/mballoc.c b/fs/ext4/mballoc.c
index 623508115d98..c3e620f6eded 100644
--- a/fs/ext4/mballoc.c
+++ b/fs/ext4/mballoc.c
@@ -3730,32 +3730,54 @@ void ext4_exit_mballoc(void)
 	ext4_groupinfo_destroy_slabs();
 }
 
+#define EXT4_MB_BITMAP_MARKED_CHECK 0x0001
+#define EXT4_MB_SYNC_UPDATE 0x0002
 struct ext4_mark_context {
+	handle_t *handle;
 	struct super_block *sb;
 	int state;
+	ext4_grpblk_t changed;
 };
 
 static int
 ext4_mb_mark_group_bb(struct ext4_mark_context *mc, ext4_group_t group,
-		      ext4_grpblk_t blkoff, ext4_grpblk_t len)
+		      ext4_grpblk_t blkoff, ext4_grpblk_t len, int flags)
 {
+	handle_t *handle = mc->handle;
 	struct super_block *sb = mc->sb;
 	struct ext4_sb_info *sbi = EXT4_SB(sb);
 	struct buffer_head *bitmap_bh = NULL;
 	struct ext4_group_desc *gdp;
 	struct buffer_head *gdp_bh;
 	int err;
-	unsigned int i, already, changed;
+	unsigned int i, already, changed = len;
 
+	mc->changed = 0;
 	bitmap_bh = ext4_read_block_bitmap(sb, group);
 	if (IS_ERR(bitmap_bh))
 		return PTR_ERR(bitmap_bh);
 
+	if (handle) {
+		BUFFER_TRACE(bitmap_bh, "getting write access");
+		err = ext4_journal_get_write_access(handle, sb, bitmap_bh,
+						    EXT4_JTR_NONE);
+		if (err)
+			goto out_err;
+	}
+
 	err = -EIO;
 	gdp = ext4_get_group_desc(sb, group, &gdp_bh);
 	if (!gdp)
 		goto out_err;
 
+	if (handle) {
+		BUFFER_TRACE(gdp_bh, "get_write_access");
+		err = ext4_journal_get_write_access(handle, sb, gdp_bh,
+						    EXT4_JTR_NONE);
+		if (err)
+			goto out_err;
+	}
+
 	ext4_lock_group(sb, group);
 	if (ext4_has_group_desc_csum(sb) &&
 	    (gdp->bg_flags & cpu_to_le16(EXT4_BG_BLOCK_UNINIT))) {
@@ -3764,12 +3786,14 @@ ext4_mb_mark_group_bb(struct ext4_mark_context *mc, ext4_group_t group,
 			ext4_free_clusters_after_init(sb, group, gdp));
 	}
 
-	already = 0;
-	for (i = 0; i < len; i++)
-		if (mb_test_bit(blkoff + i, bitmap_bh->b_data) ==
-				mc->state)
-			already++;
-	changed = len - already;
+	if (flags & EXT4_MB_BITMAP_MARKED_CHECK) {
+		already = 0;
+		for (i = 0; i < len; i++)
+			if (mb_test_bit(blkoff + i, bitmap_bh->b_data) ==
+					mc->state)
+				already++;
+		changed = len - already;
+	}
 
 	if (mc->state) {
 		mb_set_bits(bitmap_bh->b_data, blkoff, len);
@@ -3784,6 +3808,7 @@ ext4_mb_mark_group_bb(struct ext4_mark_context *mc, ext4_group_t group,
 	ext4_block_bitmap_csum_set(sb, gdp, bitmap_bh);
 	ext4_group_desc_csum_set(sb, group, gdp);
 	ext4_unlock_group(sb, group);
+	mc->changed = changed;
 
 	if (sbi->s_log_groups_per_flex) {
 		ext4_group_t flex_group = ext4_flex_group(sbi, group);
@@ -3796,15 +3821,17 @@ ext4_mb_mark_group_bb(struct ext4_mark_context *mc, ext4_group_t group,
 			atomic64_add(changed, &fg->free_clusters);
 	}
 
-	err = ext4_handle_dirty_metadata(NULL, NULL, bitmap_bh);
+	err = ext4_handle_dirty_metadata(handle, NULL, bitmap_bh);
 	if (err)
 		goto out_err;
-	err = ext4_handle_dirty_metadata(NULL, NULL, gdp_bh);
+	err = ext4_handle_dirty_metadata(handle, NULL, gdp_bh);
 	if (err)
 		goto out_err;
 
-	sync_dirty_buffer(bitmap_bh);
-	sync_dirty_buffer(gdp_bh);
+	if (flags & EXT4_MB_SYNC_UPDATE) {
+		sync_dirty_buffer(bitmap_bh);
+		sync_dirty_buffer(gdp_bh);
+	}
 
 out_err:
 	brelse(bitmap_bh);
@@ -3968,7 +3995,9 @@ void ext4_mb_mark_bb(struct super_block *sb, ext4_fsblk_t block,
 			break;
 		}
 
-		err = ext4_mb_mark_group_bb(&mc, group, blkoff, clen);
+		err = ext4_mb_mark_group_bb(&mc, group, blkoff, clen,
+					    EXT4_MB_BITMAP_MARKED_CHECK |
+					    EXT4_MB_SYNC_UPDATE);
 		if (err)
 			break;
 
@@ -6072,7 +6101,9 @@ static void ext4_free_blocks_simple(struct inode *inode, ext4_fsblk_t block,
 	ext4_grpblk_t blkoff;
 
 	ext4_get_group_no_and_offset(sb, block, &group, &blkoff);
-	ext4_mb_mark_group_bb(&mc, group, blkoff, count);
+	ext4_mb_mark_group_bb(&mc, group, blkoff, count,
+			      EXT4_MB_BITMAP_MARKED_CHECK |
+			      EXT4_MB_SYNC_UPDATE);
 }
 
 /**
-- 
2.30.0