block: don't rely on BLK_OPEN_RESTRICT_WRITES when yielding write access

Make it possible to detected a block device that was opened with
restricted write access based only on BLK_OPEN_WRITE and
bdev->bd_writers < 0 so we won't have to claim another FMODE_* flag.

Link: https://lore.kernel.org/r/20240123-vfs-bdev-file-v2-31-adbd023e19cc@kernel.org
Signed-off-by: Christian Brauner <brauner@kernel.org>

diff --git a/block/bdev.c b/block/bdev.c
index 4e4527c5df00b58085dcf95068c075915a86530d..efecc9b97e1eca8543eb74451f9883ab33f8304d 100644 (file)
--- a/block/bdev.c
+++ b/block/bdev.c
@@ -799,16 +799,21 @@ static void bdev_claim_write_access(struct block_device *bdev, blk_mode_t mode)
                bdev->bd_writers++;
 }
 
-static void bdev_yield_write_access(struct block_device *bdev, blk_mode_t mode)
+static void bdev_yield_write_access(struct file *bdev_file, blk_mode_t mode)
 {
+       struct block_device *bdev;
+
        if (bdev_allow_write_mounted)
                return;
 
+       bdev = file_bdev(bdev_file);
        /* Yield exclusive or shared write access. */
-       if (mode & BLK_OPEN_RESTRICT_WRITES)
-               bdev_unblock_writes(bdev);
-       else if (mode & BLK_OPEN_WRITE)
-               bdev->bd_writers--;
+       if (mode & BLK_OPEN_WRITE) {
+               if (bdev_writes_blocked(bdev))
+                       bdev_unblock_writes(bdev);
+               else
+                       bdev->bd_writers--;
+       }
 }
 
 /**
@@ -1020,7 +1025,7 @@ void bdev_release(struct file *bdev_file)
                sync_blockdev(bdev);
 
        mutex_lock(&disk->open_mutex);
-       bdev_yield_write_access(bdev, handle->mode);
+       bdev_yield_write_access(bdev_file, handle->mode);
 
        if (handle->holder)
                bd_end_claim(bdev, handle->holder);