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, 14 insertions, 14 deletions

diff --git a/kernel/power/swap.c b/kernel/power/swap.c
index 6053ddddaf65..692f12fe60c1 100644
--- a/kernel/power/swap.c
+++ b/kernel/power/swap.c
@@ -222,7 +222,7 @@ int swsusp_swap_in_use(void)
  */
 
 static unsigned short root_swap = 0xffff;
-static struct bdev_handle *hib_resume_bdev_handle;
+static struct file *hib_resume_bdev_file;
 
 struct hib_bio_batch {
 	atomic_t		count;
@@ -276,7 +276,7 @@ static int hib_submit_io(blk_opf_t opf, pgoff_t page_off, void *addr,
 	struct bio *bio;
 	int error = 0;
 
-	bio = bio_alloc(hib_resume_bdev_handle->bdev, 1, opf,
+	bio = bio_alloc(file_bdev(hib_resume_bdev_file), 1, opf,
 			GFP_NOIO | __GFP_HIGH);
 	bio->bi_iter.bi_sector = page_off * (PAGE_SIZE >> 9);
 
@@ -357,14 +357,14 @@ static int swsusp_swap_check(void)
 		return res;
 	root_swap = res;
 
-	hib_resume_bdev_handle = bdev_open_by_dev(swsusp_resume_device,
+	hib_resume_bdev_file = bdev_file_open_by_dev(swsusp_resume_device,
 			BLK_OPEN_WRITE, NULL, NULL);
-	if (IS_ERR(hib_resume_bdev_handle))
-		return PTR_ERR(hib_resume_bdev_handle);
+	if (IS_ERR(hib_resume_bdev_file))
+		return PTR_ERR(hib_resume_bdev_file);
 
-	res = set_blocksize(hib_resume_bdev_handle->bdev, PAGE_SIZE);
+	res = set_blocksize(file_bdev(hib_resume_bdev_file), PAGE_SIZE);
 	if (res < 0)
-		bdev_release(hib_resume_bdev_handle);
+		fput(hib_resume_bdev_file);
 
 	return res;
 }
@@ -1523,10 +1523,10 @@ int swsusp_check(bool exclusive)
 	void *holder = exclusive ? &swsusp_holder : NULL;
 	int error;
 
-	hib_resume_bdev_handle = bdev_open_by_dev(swsusp_resume_device,
+	hib_resume_bdev_file = bdev_file_open_by_dev(swsusp_resume_device,
 				BLK_OPEN_READ, holder, NULL);
-	if (!IS_ERR(hib_resume_bdev_handle)) {
-		set_blocksize(hib_resume_bdev_handle->bdev, PAGE_SIZE);
+	if (!IS_ERR(hib_resume_bdev_file)) {
+		set_blocksize(file_bdev(hib_resume_bdev_file), PAGE_SIZE);
 		clear_page(swsusp_header);
 		error = hib_submit_io(REQ_OP_READ, swsusp_resume_block,
 					swsusp_header, NULL);
@@ -1551,11 +1551,11 @@ int swsusp_check(bool exclusive)
 
 put:
 		if (error)
-			bdev_release(hib_resume_bdev_handle);
+			fput(hib_resume_bdev_file);
 		else
 			pr_debug("Image signature found, resuming\n");
 	} else {
-		error = PTR_ERR(hib_resume_bdev_handle);
+		error = PTR_ERR(hib_resume_bdev_file);
 	}
 
 	if (error)
@@ -1570,12 +1570,12 @@ put:
 
 void swsusp_close(void)
 {
-	if (IS_ERR(hib_resume_bdev_handle)) {
+	if (IS_ERR(hib_resume_bdev_file)) {
 		pr_debug("Image device not initialised\n");
 		return;
 	}
 
-	bdev_release(hib_resume_bdev_handle);
+	fput(hib_resume_bdev_file);
 }
 
 /**