ext4: sync up block and inode bitmap reading functions

ext4_read_block_bitmap and read_inode_bitmap do essentially
the same thing, and yet they are structured quite differently.
I came across this difference while looking at doing bg locking
during bg initialization.

This patch:

* removes unnecessary casts in the error messages
* renames read_inode_bitmap to ext4_read_inode_bitmap
* and more substantially, restructures the inode bitmap
  reading function to be more like the block bitmap counterpart.

The change to the inode bitmap reader simplifies the locking
to be applied in the next patch.

Signed-off-by: Eric Sandeen <sandeen@redhat.com>
Signed-off-by: Theodore Ts'o <tytso@mit.edu>

1 files changed, 29 insertions, 22 deletions

diff --git a/fs/ext4/ialloc.c b/fs/ext4/ialloc.c
index a92eb305344..09cdcd5914d 100644
--- a/fs/ext4/ialloc.c
+++ b/fs/ext4/ialloc.c
@@ -97,34 +97,41 @@ unsigned ext4_init_inode_bitmap(struct super_block *sb, struct buffer_head *bh,
  * Return buffer_head of bitmap on success or NULL.
  */
 static struct buffer_head *
-read_inode_bitmap(struct super_block *sb, ext4_group_t block_group)
+ext4_read_inode_bitmap(struct super_block *sb, ext4_group_t block_group)
 {
 	struct ext4_group_desc *desc;
 	struct buffer_head *bh = NULL;
+	ext4_fsblk_t bitmap_blk;
 
 	desc = ext4_get_group_desc(sb, block_group, NULL);
 	if (!desc)
-		goto error_out;
+		return NULL;
+	bitmap_blk = ext4_inode_bitmap(sb, desc);
+	bh = sb_getblk(sb, bitmap_blk);
+	if (unlikely(!bh)) {
+		ext4_error(sb, __func__,
+			    "Cannot read inode bitmap - "
+			    "block_group = %lu, inode_bitmap = %llu",
+			    block_group, bitmap_blk);
+		return NULL;
+	}
+	if (bh_uptodate_or_lock(bh))
+		return bh;
+
 	if (desc->bg_flags & cpu_to_le16(EXT4_BG_INODE_UNINIT)) {
-		bh = sb_getblk(sb, ext4_inode_bitmap(sb, desc));
-		if (!buffer_uptodate(bh)) {
-			lock_buffer(bh);
-			if (!buffer_uptodate(bh)) {
-				ext4_init_inode_bitmap(sb, bh, block_group,
-						       desc);
-				set_buffer_uptodate(bh);
-			}
-			unlock_buffer(bh);
-		}
-	} else {
-		bh = sb_bread(sb, ext4_inode_bitmap(sb, desc));
+		ext4_init_inode_bitmap(sb, bh, block_group, desc);
+		set_buffer_uptodate(bh);
+		unlock_buffer(bh);
+		return bh;
 	}
-	if (!bh)
-		ext4_error(sb, "read_inode_bitmap",
+	if (bh_submit_read(bh) < 0) {
+		put_bh(bh);
+		ext4_error(sb, __func__,
 			    "Cannot read inode bitmap - "
 			    "block_group = %lu, inode_bitmap = %llu",
-			    block_group, ext4_inode_bitmap(sb, desc));
-error_out:
+			    block_group, bitmap_blk);
+		return NULL;
+	}
 	return bh;
 }
 
@@ -200,7 +207,7 @@ void ext4_free_inode (handle_t *handle, struct inode * inode)
 	}
 	block_group = (ino - 1) / EXT4_INODES_PER_GROUP(sb);
 	bit = (ino - 1) % EXT4_INODES_PER_GROUP(sb);
-	bitmap_bh = read_inode_bitmap(sb, block_group);
+	bitmap_bh = ext4_read_inode_bitmap(sb, block_group);
 	if (!bitmap_bh)
 		goto error_return;
 
@@ -623,7 +630,7 @@ got_group:
 			goto fail;
 
 		brelse(bitmap_bh);
-		bitmap_bh = read_inode_bitmap(sb, group);
+		bitmap_bh = ext4_read_inode_bitmap(sb, group);
 		if (!bitmap_bh)
 			goto fail;
 
@@ -891,7 +898,7 @@ struct inode *ext4_orphan_get(struct super_block *sb, unsigned long ino)
 
 	block_group = (ino - 1) / EXT4_INODES_PER_GROUP(sb);
 	bit = (ino - 1) % EXT4_INODES_PER_GROUP(sb);
-	bitmap_bh = read_inode_bitmap(sb, block_group);
+	bitmap_bh = ext4_read_inode_bitmap(sb, block_group);
 	if (!bitmap_bh) {
 		ext4_warning(sb, __func__,
 			     "inode bitmap error for orphan %lu", ino);
@@ -969,7 +976,7 @@ unsigned long ext4_count_free_inodes (struct super_block * sb)
 			continue;
 		desc_count += le16_to_cpu(gdp->bg_free_inodes_count);
 		brelse(bitmap_bh);
-		bitmap_bh = read_inode_bitmap(sb, i);
+		bitmap_bh = ext4_read_inode_bitmap(sb, i);
 		if (!bitmap_bh)
 			continue;