Merge series 'Open block devices as files' of https://lore.kernel.org/r/20240123-vfs-bdev-file-v2-0-adbd023e19cc@kernel.org

Pull block devices as files from Christian Brauner:

This opens block devices as files. Instead of introducing a separate
indirection into bdev_open_by_*() vis struct bdev_handle we can just
make bdev_file_open_by_*() return a struct file. Opening and closing a
block device from setup_bdev_super() and in all other places just
becomes equivalent to opening and closing a file.

This has held up in xfstests and in blktests so far and it seems stable
and clean. The equivalence of opening and closing block devices to
regular files is a win in and of itself imho. Added to that is the
ability to do away with struct bdev_handle completely and make various
low-level helpers private to the block layer.

All places were we currently stash a struct bdev_handle we just stash a
file and use an accessor such as file_bdev() akin to I_BDEV() to get to
the block device.

It's now also possible to use file->f_mapping as a replacement for
bdev->bd_inode->i_mapping and file->f_inode or file->f_mapping->host as
an alternative to bdev->bd_inode allowing us to significantly reduce or
even fully remove bdev->bd_inode in follow-up patches.

In addition, we could get rid of sb->s_bdev and various other places
that stash the block device directly and instead stash the block device
file. Again, this is follow-up work if we want this.

* series 'Open block devices as files' of https://lore.kernel.org/r/20240123-vfs-bdev-file-v2-0-adbd023e19cc@kernel.org: (35 commits)
  file: add alloc_file_pseudo_noaccount()
  file: prepare for new helper
  init: flush async file closing
  block: remove bdev_handle completely
  block: don't rely on BLK_OPEN_RESTRICT_WRITES when yielding write access
  bdev: remove bdev pointer from struct bdev_handle
  bdev: make struct bdev_handle private to the block layer
  bdev: make bdev_{release, open_by_dev}() private to block layer
  bdev: remove bdev_open_by_path()
  reiserfs: port block device access to file
  ocfs2: port block device access to file
  nfs: port block device access to files
  jfs: port block device access to file
  f2fs: port block device access to files
  ext4: port block device access to file
  erofs: port device access to file
  btrfs: port device access to file
  bcachefs: port block device access to file
  target: port block device access to file
  s390: port block device access to file
  nvme: port block device access to file
  block2mtd: port device access to files
  bcache: port block device access to files
  ...

Signed-off-by: Christian Brauner <brauner@kernel.org>

2 files changed, 7 insertions, 7 deletions

diff --git a/fs/f2fs/f2fs.h b/fs/f2fs/f2fs.h
index 65294e3b0bef..6fc172c99915 100644
--- a/fs/f2fs/f2fs.h
+++ b/fs/f2fs/f2fs.h
@@ -1239,7 +1239,7 @@ struct f2fs_bio_info {
 #define FDEV(i)				(sbi->devs[i])
 #define RDEV(i)				(raw_super->devs[i])
 struct f2fs_dev_info {
-	struct bdev_handle *bdev_handle;
+	struct file *bdev_file;
 	struct block_device *bdev;
 	char path[MAX_PATH_LEN];
 	unsigned int total_segments;
diff --git a/fs/f2fs/super.c b/fs/f2fs/super.c
index d45ab0992ae5..557ea5c6c926 100644
--- a/fs/f2fs/super.c
+++ b/fs/f2fs/super.c
@@ -1605,7 +1605,7 @@ static void destroy_device_list(struct f2fs_sb_info *sbi)
 
 	for (i = 0; i < sbi->s_ndevs; i++) {
 		if (i > 0)
-			bdev_release(FDEV(i).bdev_handle);
+			fput(FDEV(i).bdev_file);
 #ifdef CONFIG_BLK_DEV_ZONED
 		kvfree(FDEV(i).blkz_seq);
 #endif
@@ -4247,7 +4247,7 @@ static int f2fs_scan_devices(struct f2fs_sb_info *sbi)
 
 	for (i = 0; i < max_devices; i++) {
 		if (i == 0)
-			FDEV(0).bdev_handle = sbi->sb->s_bdev_handle;
+			FDEV(0).bdev_file = sbi->sb->s_bdev_file;
 		else if (!RDEV(i).path[0])
 			break;
 
@@ -4267,14 +4267,14 @@ static int f2fs_scan_devices(struct f2fs_sb_info *sbi)
 				FDEV(i).end_blk = FDEV(i).start_blk +
 					(FDEV(i).total_segments <<
 					sbi->log_blocks_per_seg) - 1;
-				FDEV(i).bdev_handle = bdev_open_by_path(
+				FDEV(i).bdev_file = bdev_file_open_by_path(
 					FDEV(i).path, mode, sbi->sb, NULL);
 			}
 		}
-		if (IS_ERR(FDEV(i).bdev_handle))
-			return PTR_ERR(FDEV(i).bdev_handle);
+		if (IS_ERR(FDEV(i).bdev_file))
+			return PTR_ERR(FDEV(i).bdev_file);
 
-		FDEV(i).bdev = FDEV(i).bdev_handle->bdev;
+		FDEV(i).bdev = file_bdev(FDEV(i).bdev_file);
 		/* to release errored devices */
 		sbi->s_ndevs = i + 1;