[PATCH v2 32/34] block: remove bdev_handle completely

Christian Brauner
2024-01-23T13:28:16Z

We just need to use the holder to indicate whether a block device open
was exclusive or not. We did use to do that before but had to give that
up once we switched to struct bdev_handle. Before struct bdev_handle we
only stashed stuff in file->private_data if this was an exclusive open
but after struct bdev_handle we always set file->private_data to a
struct bdev_handle and so we had to use bdev_handle->mode or
bdev_handle->holder. Now that we don't use struct bdev_handle anymore we
can revert back to the old behavior.

Signed-off-by: Christian Brauner <brauner@kernel.org>
---
block/bdev.c | 24 +++++++-----------------
block/blk.h | 5 -----
block/fops.c | 18 +++++++++++-------
3 files changed, 18 insertions(+), 29 deletions(-)

diff --git a/block/bdev.c b/block/bdev.c
index 9d96a43f198d..4b47003d8082 100644
--- a/block/bdev.c
+++ b/block/bdev.c
@@ -799,7 +799,7 @@ static void bdev_claim_write_access(struct block_device *bdev, blk_mode_t mode)
bdev->bd_writers++;
}

-static void bdev_yield_write_access(struct file *bdev_file, blk_mode_t mode)
+static void bdev_yield_write_access(struct file *bdev_file)
{
struct block_device *bdev;

@@ -810,7 +810,7 @@ static void bdev_yield_write_access(struct file *bdev_file, blk_mode_t mode)
/* Yield exclusive or shared write access. */
if (bdev_file->f_op == &def_blk_fops_restricted)
bdev_unblock_writes(bdev);
- else if (mode & BLK_OPEN_WRITE)
+ else if (bdev_file->f_mode & FMODE_WRITE)
bdev->bd_writers--;
}

@@ -838,16 +838,10 @@ static void bdev_yield_write_access(struct file *bdev_file, blk_mode_t mode)
int bdev_open(struct block_device *bdev, blk_mode_t mode, void *holder,
const struct blk_holder_ops *hops, struct file *bdev_file)
{
- struct bdev_handle *handle = kmalloc(sizeof(struct bdev_handle),
- GFP_KERNEL);
bool unblock_events = true;
struct gendisk *disk = bdev->bd_disk;
int ret;

- handle = kmalloc(sizeof(struct bdev_handle), GFP_KERNEL);
- if (!handle)
- return -ENOMEM;
-
if (holder) {
mode |= BLK_OPEN_EXCL;
ret = bd_prepare_to_claim(bdev, holder, hops);
@@ -896,8 +890,6 @@ int bdev_open(struct block_device *bdev, blk_mode_t mode, void *holder,

if (unblock_events)
disk_unblock_events(disk);
- handle->holder = holder;
- handle->mode = mode;

/*
* Preserve backwards compatibility and allow large file access
@@ -911,7 +903,7 @@ int bdev_open(struct block_device *bdev, blk_mode_t mode, void *holder,
bdev_file->f_mode |= FMODE_NOWAIT;
bdev_file->f_mapping = bdev->bd_inode->i_mapping;
bdev_file->f_wb_err = filemap_sample_wb_err(bdev_file->f_mapping);
- bdev_file->private_data = handle;
+ bdev_file->private_data = holder;

return 0;
put_module:
@@ -921,7 +913,6 @@ int bdev_open(struct block_device *bdev, blk_mode_t mode, void *holder,
bd_abort_claiming(bdev, holder);
mutex_unlock(&disk->open_mutex);
disk_unblock_events(disk);
- kfree(handle);
return ret;
}

@@ -1027,7 +1018,7 @@ EXPORT_SYMBOL(bdev_file_open_by_path);
void bdev_release(struct file *bdev_file)
{
struct block_device *bdev = file_bdev(bdev_file);
- struct bdev_handle *handle = bdev_file->private_data;
+ void *holder = bdev_file->private_data;
struct gendisk *disk = bdev->bd_disk;

/*
@@ -1041,10 +1032,10 @@ void bdev_release(struct file *bdev_file)
sync_blockdev(bdev);

mutex_lock(&disk->open_mutex);
- bdev_yield_write_access(bdev_file, handle->mode);
+ bdev_yield_write_access(bdev_file);

- if (handle->holder)
- bd_end_claim(bdev, handle->holder);
+ if (holder)
+ bd_end_claim(bdev, holder);

/*
* Trigger event checking and tell drivers to flush MEDIA_CHANGE
@@ -1061,7 +1052,6 @@ void bdev_release(struct file *bdev_file)

module_put(disk->fops->owner);
blkdev_put_no_open(bdev);
- kfree(handle);
}

/**
diff --git a/block/blk.h b/block/blk.h
index dfa958909c54..cce1ac0ff303 100644
--- a/block/blk.h
+++ b/block/blk.h
@@ -27,11 +27,6 @@ struct blk_flush_queue {
struct request *flush_rq;
};

-struct bdev_handle {
- void *holder;
- blk_mode_t mode;
-};
-
bool is_flush_rq(struct request *req);

struct blk_flush_queue *blk_alloc_flush_queue(int node, int cmd_size,
diff --git a/block/fops.c b/block/fops.c
index f56bdfe459de..a0bff2c0d88d 100644
--- a/block/fops.c
+++ b/block/fops.c
@@ -569,7 +569,6 @@ static int blkdev_fsync(struct file *filp, loff_t start, loff_t end,
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;
@@ -579,8 +578,8 @@ blk_mode_t file_to_blk_mode(struct file *file)
* 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;
+ if (file->private_data)
+ mode |= BLK_OPEN_EXCL;
else if (file->f_flags & O_EXCL)
mode |= BLK_OPEN_EXCL;
if (file->f_flags & O_NDELAY)
@@ -601,12 +600,17 @@ static int blkdev_open(struct inode *inode, struct file *filp)
{
struct block_device *bdev;
blk_mode_t mode;
- void *holder;
int ret;

+ /*
+ * Use the file private data to store the holder for exclusive opens.
+ * file_to_blk_mode relies on it being present to set BLK_OPEN_EXCL.
+ */
+ if (filp->f_flags & O_EXCL)
+ filp->private_data = filp;
+
mode = file_to_blk_mode(filp);
- holder = mode & BLK_OPEN_EXCL ? filp : NULL;
- ret = bdev_permission(inode->i_rdev, mode, holder);
+ ret = bdev_permission(inode->i_rdev, mode, filp->private_data);
if (ret)
return ret;

@@ -614,7 +618,7 @@ static int blkdev_open(struct inode *inode, struct file *filp)
if (!bdev)
return -ENXIO;

- ret = bdev_open(bdev, mode, holder, NULL, filp);
+ ret = bdev_open(bdev, mode, filp->private_data, NULL, filp);
if (ret)
blkdev_put_no_open(bdev);
return ret;

--
2.43.0