block: remove __sync_blockdev

Instead offer a new sync_blockdev_nowait helper for the !wait case.
This new helper is exported as it will grow modular callers in a bit.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Link: https://lore.kernel.org/r/20211019062530.2174626-3-hch@lst.de
Signed-off-by: Jens Axboe <axboe@kernel.dk>

block/bdev.c

@@ -185,14 +185,13 @@ int sb_min_blocksize(struct super_block *sb, int size)
 
 EXPORT_SYMBOL(sb_min_blocksize);
 
-int __sync_blockdev(struct block_device *bdev, int wait)
+int sync_blockdev_nowait(struct block_device *bdev)
 {
 	if (!bdev)
 		return 0;
-	if (!wait)
-		return filemap_flush(bdev->bd_inode->i_mapping);
-	return filemap_write_and_wait(bdev->bd_inode->i_mapping);
+	return filemap_flush(bdev->bd_inode->i_mapping);
 }
+EXPORT_SYMBOL_GPL(sync_blockdev_nowait);
 
 /*
  * Write out and wait upon all the dirty data associated with a block
@@ -200,7 +199,9 @@ int __sync_blockdev(struct block_device *bdev, int wait)
  */
 int sync_blockdev(struct block_device *bdev)
 {
-	return __sync_blockdev(bdev, 1);
+	if (!bdev)
+		return 0;
+	return filemap_write_and_wait(bdev->bd_inode->i_mapping);
 }
 EXPORT_SYMBOL(sync_blockdev);
 

fs/internal.h

@@ -23,7 +23,6 @@ struct pipe_inode_info;
 #ifdef CONFIG_BLOCK
 extern void __init bdev_cache_init(void);
 
-extern int __sync_blockdev(struct block_device *bdev, int wait);
 void iterate_bdevs(void (*)(struct block_device *, void *), void *);
 void emergency_thaw_bdev(struct super_block *sb);
 #else
@@ -31,10 +30,6 @@ static inline void bdev_cache_init(void)
 {
 }
 
-static inline int __sync_blockdev(struct block_device *bdev, int wait)
-{
-	return 0;
-}
 static inline void iterate_bdevs(void (*f)(struct block_device *, void *),
 		void *arg)
 {

fs/sync.c

@@ -3,6 +3,7 @@
  * High-level sync()-related operations
  */
 
+#include <linux/blkdev.h>
 #include <linux/kernel.h>
 #include <linux/file.h>
 #include <linux/fs.h>
@@ -45,7 +46,7 @@ int sync_filesystem(struct super_block *sb)
 	/*
 	 * Do the filesystem syncing work.  For simple filesystems
 	 * writeback_inodes_sb(sb) just dirties buffers with inodes so we have
-	 * to submit I/O for these buffers via __sync_blockdev().  This also
+	 * to submit I/O for these buffers via sync_blockdev().  This also
 	 * speeds up the wait == 1 case since in that case write_inode()
 	 * methods call sync_dirty_buffer() and thus effectively write one block
 	 * at a time.
@@ -53,14 +54,14 @@ int sync_filesystem(struct super_block *sb)
 	writeback_inodes_sb(sb, WB_REASON_SYNC);
 	if (sb->s_op->sync_fs)
 		sb->s_op->sync_fs(sb, 0);
-	ret = __sync_blockdev(sb->s_bdev, 0);
+	ret = sync_blockdev_nowait(sb->s_bdev);
 	if (ret < 0)
 		return ret;
 
 	sync_inodes_sb(sb);
 	if (sb->s_op->sync_fs)
 		sb->s_op->sync_fs(sb, 1);
-	return __sync_blockdev(sb->s_bdev, 1);
+	return sync_blockdev(sb->s_bdev);
 }
 EXPORT_SYMBOL(sync_filesystem);
 

include/linux/blkdev.h

@@ -1266,6 +1266,7 @@ int truncate_bdev_range(struct block_device *bdev, fmode_t mode, loff_t lstart,
 #ifdef CONFIG_BLOCK
 void invalidate_bdev(struct block_device *bdev);
 int sync_blockdev(struct block_device *bdev);
+int sync_blockdev_nowait(struct block_device *bdev);
 #else
 static inline void invalidate_bdev(struct block_device *bdev)
 {
@@ -1274,6 +1275,10 @@ static inline int sync_blockdev(struct block_device *bdev)
 {
 	return 0;
 }
+static inline int sync_blockdev_nowait(struct block_device *bdev)
+{
+	return 0;
+}
 #endif
 int fsync_bdev(struct block_device *bdev);