ext4: use unlikely to improve the efficiency of the kernel

Because the function 'sb_getblk' seldomly fails to return NULL
value,it will be better to use 'unlikely' to optimize it.

Signed-off-by: Wang Shilong <wangsl-fnst@cn.fujitsu.com>
Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>

fs/ext4/extents.c

@@ -956,7 +956,7 @@ static int ext4_ext_split(handle_t *handle, struct inode *inode,
 		goto cleanup;
 	}
 	bh = sb_getblk(inode->i_sb, newblock);
-	if (!bh) {
+	if (unlikely(!bh)) {
 		err = -ENOMEM;
 		goto cleanup;
 	}
@@ -1029,7 +1029,7 @@ static int ext4_ext_split(handle_t *handle, struct inode *inode,
 		oldblock = newblock;
 		newblock = ablocks[--a];
 		bh = sb_getblk(inode->i_sb, newblock);
-		if (!bh) {
+		if (unlikely(!bh)) {
 			err = -ENOMEM;
 			goto cleanup;
 		}
@@ -1142,7 +1142,7 @@ static int ext4_ext_grow_indepth(handle_t *handle, struct inode *inode,
 		return err;
 
 	bh = sb_getblk(inode->i_sb, newblock);
-	if (!bh)
+	if (unlikely(!bh))
 		return -ENOMEM;
 	lock_buffer(bh);
 

fs/ext4/inode.c

@@ -713,7 +713,7 @@ struct buffer_head *ext4_getblk(handle_t *handle, struct inode *inode,
 		return NULL;
 
 	bh = sb_getblk(inode->i_sb, map.m_pblk);
-	if (!bh) {
+	if (unlikely(!bh)) {
 		*errp = -ENOMEM;
 		return NULL;
 	}
@@ -3660,7 +3660,7 @@ static int __ext4_get_inode_loc(struct inode *inode,
 	iloc->offset = (inode_offset % inodes_per_block) * EXT4_INODE_SIZE(sb);
 
 	bh = sb_getblk(sb, block);
-	if (!bh)
+	if (unlikely(!bh))
 		return -ENOMEM;
 	if (!buffer_uptodate(bh)) {
 		lock_buffer(bh);
@@ -3693,7 +3693,7 @@ static int __ext4_get_inode_loc(struct inode *inode,
 
 			/* Is the inode bitmap in cache? */
 			bitmap_bh = sb_getblk(sb, ext4_inode_bitmap(sb, gdp));
-			if (!bitmap_bh)
+			if (unlikely(!bitmap_bh))
 				goto make_io;
 
 			/*

fs/ext4/mmp.c

@@ -93,7 +93,7 @@ static int read_mmp_block(struct super_block *sb, struct buffer_head **bh,
 			*bh = NULL;
 		}
 	}
-	if (!*bh) {
+	if (unlikely(!*bh)) {
 		ext4_warning(sb, "Error while reading MMP block %llu",
 			     mmp_block);
 		return -EIO;

fs/ext4/resize.c

@@ -333,7 +333,7 @@ static struct buffer_head *bclean(handle_t *handle, struct super_block *sb,
 	int err;
 
 	bh = sb_getblk(sb, blk);
-	if (!bh)
+	if (unlikely(!bh))
 		return ERR_PTR(-ENOMEM);
 	if ((err = ext4_journal_get_write_access(handle, bh))) {
 		brelse(bh);
@@ -410,7 +410,7 @@ static int set_flexbg_block_bitmap(struct super_block *sb, handle_t *handle,
 			return err;
 
 		bh = sb_getblk(sb, flex_gd->groups[group].block_bitmap);
-		if (!bh)
+		if (unlikely(!bh))
 			return -ENOMEM;
 
 		err = ext4_journal_get_write_access(handle, bh);
@@ -500,7 +500,7 @@ static int setup_new_flex_group_blocks(struct super_block *sb,
 				goto out;
 
 			gdb = sb_getblk(sb, block);
-			if (!gdb) {
+			if (unlikely(!gdb)) {
 				err = -ENOMEM;
 				goto out;
 			}
@@ -1064,7 +1064,7 @@ static void update_backups(struct super_block *sb, int blk_off, char *data,
 					ext4_bg_has_super(sb, group));
 
 		bh = sb_getblk(sb, backup_block);
-		if (!bh) {
+		if (unlikely(!bh)) {
 			err = -ENOMEM;
 			break;
 		}
@@ -1168,7 +1168,7 @@ static int ext4_add_new_descs(handle_t *handle, struct super_block *sb,
 static struct buffer_head *ext4_get_bitmap(struct super_block *sb, __u64 block)
 {
 	struct buffer_head *bh = sb_getblk(sb, block);
-	if (!bh)
+	if (unlikely(!bh))
 		return NULL;
 	if (!bh_uptodate_or_lock(bh)) {
 		if (bh_submit_read(bh) < 0) {

fs/ext4/xattr.c

@@ -886,7 +886,7 @@ ext4_xattr_block_set(handle_t *handle, struct inode *inode,
 				  (unsigned long long)block);
 
 			new_bh = sb_getblk(sb, block);
-			if (!new_bh) {
+			if (unlikely(!new_bh)) {
 				error = -ENOMEM;
 getblk_failed:
 				ext4_free_blocks(handle, inode, NULL, block, 1,