block: Use bdev_open_by_dev() in blkdev_open()

Convert blkdev_open() to use bdev_open_by_dev(). To be able to propagate
handle from blkdev_open() to blkdev_release() we need to stop using
existence of file->private_data to determine exclusive block device
opens. Use bdev_handle->mode for this purpose since file->f_flags
isn't usable for this (O_EXCL is cleared from the flags during open).

Acked-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Christian Brauner <brauner@kernel.org>
Signed-off-by: Jan Kara <jack@suse.cz>
Link: https://lore.kernel.org/r/20230927093442.25915-2-jack@suse.cz
Signed-off-by: Christian Brauner <brauner@kernel.org>

diff --git a/block/bdev.c b/block/bdev.c
index bdc7d739882bb04486a83e0a27630fb933c348f5..4628dcb1da8a58fee1d8002b0c42fdff9a109b46 100644 (file)
--- a/block/bdev.c
+++ b/block/bdev.c
@@ -844,6 +844,9 @@ struct bdev_handle *bdev_open_by_dev(dev_t dev, blk_mode_t mode, void *holder,
        }
        handle->bdev = bdev;
        handle->holder = holder;
+       if (holder)
+               mode |= BLK_OPEN_EXCL;
+       handle->mode = mode;
        return handle;
 }
 EXPORT_SYMBOL(bdev_open_by_dev);

diff --git a/block/fops.c b/block/fops.c
index 73e42742543f6a62975f0f94c90a6d6f42e3eaff..0abaac705dafb08bf26078a7d3048c12916067c6 100644 (file)
--- a/block/fops.c
+++ b/block/fops.c
@@ -542,15 +542,31 @@ static int blkdev_fsync(struct file *filp, loff_t start, loff_t end,
        return error;
 }
 
+/**
+ * file_to_blk_mode - get block open flags from file flags
+ * @file: file whose open flags should be converted
+ *
+ * Look at file open flags and generate corresponding block open flags from
+ * them. The function works both for file just being open (e.g. during ->open
+ * callback) and for file that is already open. This is actually non-trivial
+ * (see comment in the function).
+ */
 blk_mode_t file_to_blk_mode(struct file *file)
 {
        blk_mode_t mode = 0;
+       struct bdev_handle *handle = file->private_data;
 
        if (file->f_mode & FMODE_READ)
                mode |= BLK_OPEN_READ;
        if (file->f_mode & FMODE_WRITE)
                mode |= BLK_OPEN_WRITE;
-       if (file->private_data)
+       /*
+        * do_dentry_open() clears O_EXCL from f_flags, use handle->mode to
+        * determine whether the open was exclusive for already open files.
+        */
+       if (handle)
+               mode |= handle->mode & BLK_OPEN_EXCL;
+       else if (file->f_flags & O_EXCL)
                mode |= BLK_OPEN_EXCL;
        if (file->f_flags & O_NDELAY)
                mode |= BLK_OPEN_NDELAY;
@@ -568,7 +584,8 @@ blk_mode_t file_to_blk_mode(struct file *file)
 
 static int blkdev_open(struct inode *inode, struct file *filp)
 {
-       struct block_device *bdev;
+       struct bdev_handle *handle;
+       blk_mode_t mode;
 
        /*
         * Preserve backwards compatibility and allow large file access
@@ -579,29 +596,24 @@ static int blkdev_open(struct inode *inode, struct file *filp)
        filp->f_flags |= O_LARGEFILE;
        filp->f_mode |= FMODE_BUF_RASYNC | FMODE_CAN_ODIRECT;
 
-       /*
-        * Use the file private data to store the holder for exclusive openes.
-        * file_to_blk_mode relies on it being present to set BLK_OPEN_EXCL.
-        */
-       if (filp->f_flags & O_EXCL)
-               filp->private_data = filp;
-
-       bdev = blkdev_get_by_dev(inode->i_rdev, file_to_blk_mode(filp),
-                                filp->private_data, NULL);
-       if (IS_ERR(bdev))
-               return PTR_ERR(bdev);
+       mode = file_to_blk_mode(filp);
+       handle = bdev_open_by_dev(inode->i_rdev, mode,
+                       mode & BLK_OPEN_EXCL ? filp : NULL, NULL);
+       if (IS_ERR(handle))
+               return PTR_ERR(handle);
 
-       if (bdev_nowait(bdev))
+       if (bdev_nowait(handle->bdev))
                filp->f_mode |= FMODE_NOWAIT;
 
-       filp->f_mapping = bdev->bd_inode->i_mapping;
+       filp->f_mapping = handle->bdev->bd_inode->i_mapping;
        filp->f_wb_err = filemap_sample_wb_err(filp->f_mapping);
+       filp->private_data = handle;
        return 0;
 }
 
 static int blkdev_release(struct inode *inode, struct file *filp)
 {
-       blkdev_put(I_BDEV(filp->f_mapping->host), filp->private_data);
+       bdev_release(filp->private_data);
        return 0;
 }
 

diff --git a/include/linux/blkdev.h b/include/linux/blkdev.h
index 03d3adc3ff347d129b6b9b844ffa0cd12f8c4e80..51fa7ffdee83b434676cf4fe07e50d6507cfd1ae 100644 (file)
--- a/include/linux/blkdev.h
+++ b/include/linux/blkdev.h
@@ -1482,6 +1482,7 @@ extern const struct blk_holder_ops fs_holder_ops;
 struct bdev_handle {
        struct block_device *bdev;
        void *holder;
+       blk_mode_t mode;
 };
 
 struct block_device *blkdev_get_by_dev(dev_t dev, blk_mode_t mode, void *holder,