From f3a608827d1f8de0dd12813e8d9c6803fe64e119 Mon Sep 17 00:00:00 2001 From: Christian Brauner Date: Thu, 8 Feb 2024 18:47:35 +0100 Subject: bdev: open block device as files Add two new helpers to allow opening block devices as files. This is not the final infrastructure. This still opens the block device before opening a struct a file. Until we have removed all references to struct bdev_handle we can't switch the order: * Introduce blk_to_file_flags() to translate from block specific to flags usable to pen a new file. * Introduce bdev_file_open_by_{dev,path}(). * Introduce temporary sb_bdev_handle() helper to retrieve a struct bdev_handle from a block device file and update places that directly reference struct bdev_handle to rely on it. * Don't count block device openes against the number of open files. A bdev_file_open_by_{dev,path}() file is never installed into any file descriptor table. One idea that came to mind was to use kernel_tmpfile_open() which would require us to pass a path and it would then call do_dentry_open() going through the regular fops->open::blkdev_open() path. But then we're back to the problem of routing block specific flags such as BLK_OPEN_RESTRICT_WRITES through the open path and would have to waste FMODE_* flags every time we add a new one. With this we can avoid using a flag bit and we have more leeway in how we open block devices from bdev_open_by_{dev,path}(). Link: https://lore.kernel.org/r/20240123-vfs-bdev-file-v2-1-adbd023e19cc@kernel.org Signed-off-by: Christian Brauner --- fs/super.c | 18 +++++++++--------- 1 file changed, 9 insertions(+), 9 deletions(-) (limited to 'fs/super.c') diff --git a/fs/super.c b/fs/super.c index d35e85295489..08dcc3371aa0 100644 --- a/fs/super.c +++ b/fs/super.c @@ -1532,16 +1532,16 @@ int setup_bdev_super(struct super_block *sb, int sb_flags, struct fs_context *fc) { blk_mode_t mode = sb_open_mode(sb_flags); - struct bdev_handle *bdev_handle; + struct file *bdev_file; struct block_device *bdev; - bdev_handle = bdev_open_by_dev(sb->s_dev, mode, sb, &fs_holder_ops); - if (IS_ERR(bdev_handle)) { + bdev_file = bdev_file_open_by_dev(sb->s_dev, mode, sb, &fs_holder_ops); + if (IS_ERR(bdev_file)) { if (fc) errorf(fc, "%s: Can't open blockdev", fc->source); - return PTR_ERR(bdev_handle); + return PTR_ERR(bdev_file); } - bdev = bdev_handle->bdev; + bdev = file_bdev(bdev_file); /* * This really should be in blkdev_get_by_dev, but right now can't due @@ -1549,7 +1549,7 @@ int setup_bdev_super(struct super_block *sb, int sb_flags, * writable from userspace even for a read-only block device. */ if ((mode & BLK_OPEN_WRITE) && bdev_read_only(bdev)) { - bdev_release(bdev_handle); + fput(bdev_file); return -EACCES; } @@ -1560,11 +1560,11 @@ int setup_bdev_super(struct super_block *sb, int sb_flags, if (atomic_read(&bdev->bd_fsfreeze_count) > 0) { if (fc) warnf(fc, "%pg: Can't mount, blockdev is frozen", bdev); - bdev_release(bdev_handle); + fput(bdev_file); return -EBUSY; } spin_lock(&sb_lock); - sb->s_bdev_handle = bdev_handle; + sb->s_bdev_file = bdev_file; sb->s_bdev = bdev; sb->s_bdi = bdi_get(bdev->bd_disk->bdi); if (bdev_stable_writes(bdev)) @@ -1680,7 +1680,7 @@ void kill_block_super(struct super_block *sb) generic_shutdown_super(sb); if (bdev) { sync_blockdev(bdev); - bdev_release(sb->s_bdev_handle); + fput(sb->s_bdev_file); } } -- cgit