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>

1 files changed, 11 insertions, 11 deletions

diff --git a/mm/swapfile.c b/mm/swapfile.c
index 556ff7347d5f..73edd6fed6a2 100644
--- a/mm/swapfile.c
+++ b/mm/swapfile.c
@@ -2532,10 +2532,10 @@ SYSCALL_DEFINE1(swapoff, const char __user *, specialfile)
 	exit_swap_address_space(p->type);
 
 	inode = mapping->host;
-	if (p->bdev_handle) {
+	if (p->bdev_file) {
 		set_blocksize(p->bdev, old_block_size);
-		bdev_release(p->bdev_handle);
-		p->bdev_handle = NULL;
+		fput(p->bdev_file);
+		p->bdev_file = NULL;
 	}
 
 	inode_lock(inode);
@@ -2765,14 +2765,14 @@ static int claim_swapfile(struct swap_info_struct *p, struct inode *inode)
 	int error;
 
 	if (S_ISBLK(inode->i_mode)) {
-		p->bdev_handle = bdev_open_by_dev(inode->i_rdev,
+		p->bdev_file = bdev_file_open_by_dev(inode->i_rdev,
 				BLK_OPEN_READ | BLK_OPEN_WRITE, p, NULL);
-		if (IS_ERR(p->bdev_handle)) {
-			error = PTR_ERR(p->bdev_handle);
-			p->bdev_handle = NULL;
+		if (IS_ERR(p->bdev_file)) {
+			error = PTR_ERR(p->bdev_file);
+			p->bdev_file = NULL;
 			return error;
 		}
-		p->bdev = p->bdev_handle->bdev;
+		p->bdev = file_bdev(p->bdev_file);
 		p->old_block_size = block_size(p->bdev);
 		error = set_blocksize(p->bdev, PAGE_SIZE);
 		if (error < 0)
@@ -3208,10 +3208,10 @@ bad_swap:
 	p->percpu_cluster = NULL;
 	free_percpu(p->cluster_next_cpu);
 	p->cluster_next_cpu = NULL;
-	if (p->bdev_handle) {
+	if (p->bdev_file) {
 		set_blocksize(p->bdev, p->old_block_size);
-		bdev_release(p->bdev_handle);
-		p->bdev_handle = NULL;
+		fput(p->bdev_file);
+		p->bdev_file = NULL;
 	}
 	inode = NULL;
 	destroy_swap_extents(p);