diff mbox series

[01/31] block: also call ->open for incremental partition opens

Message ID 20230606073950.225178-2-hch@lst.de (mailing list archive)
State Under Review
Headers show
Series [01/31] block: also call ->open for incremental partition opens | expand

Commit Message

Christoph Hellwig June 6, 2023, 7:39 a.m. UTC
For whole devices ->open is called for each open, but for partitions it
is only called on the first open of a partition.  This is problematic
as various block drivers look at open flags and might not do all setup
for ioctl only or NDELAY opens.

Signed-off-by: Christoph Hellwig <hch@lst.de>
---
 block/bdev.c | 18 ++++++++----------
 1 file changed, 8 insertions(+), 10 deletions(-)

Comments

Christian Brauner June 7, 2023, 8:14 a.m. UTC | #1
On Tue, Jun 06, 2023 at 09:39:20AM +0200, Christoph Hellwig wrote:
> For whole devices ->open is called for each open, but for partitions it
> is only called on the first open of a partition.  This is problematic
> as various block drivers look at open flags and might not do all setup
> for ioctl only or NDELAY opens.
> 
> Signed-off-by: Christoph Hellwig <hch@lst.de>
> ---

This assumes that all drivers deal with additional ->open() calls for
each partition correctly which I assumed you checked so,
Acked-by: Christian Brauner <brauner@kernel.org>
Christoph Hellwig June 7, 2023, 8:32 a.m. UTC | #2
On Wed, Jun 07, 2023 at 10:14:22AM +0200, Christian Brauner wrote:
> This assumes that all drivers deal with additional ->open() calls for
> each partition correctly which I assumed you checked so,

They have to, because they already get the additional open for
extra opens of the whole device.  The current behavior is:

open("/dev/vdb", ...)
  ->open called

open("/dev/vdb", ...)
  ->open called

----

open("/dev/vdb", ...)
  ->open called

open("/dev/vdb1", ...)
  ->open called

----

open("/dev/vdb1", ...)
  ->open called

open("/dev/vdb1", ...)
  ->open NOT called

which is very inconsistent.
Hannes Reinecke June 7, 2023, 12:10 p.m. UTC | #3
On 6/6/23 09:39, Christoph Hellwig wrote:
> For whole devices ->open is called for each open, but for partitions it
> is only called on the first open of a partition.  This is problematic
> as various block drivers look at open flags and might not do all setup
> for ioctl only or NDELAY opens.
> 
> Signed-off-by: Christoph Hellwig <hch@lst.de>
> ---
>   block/bdev.c | 18 ++++++++----------
>   1 file changed, 8 insertions(+), 10 deletions(-)
> 
Reviewed-by: Hannes Reinecke <hare@suse.de>

Cheers,

Hannes
diff mbox series

Patch

diff --git a/block/bdev.c b/block/bdev.c
index 5c46ff10770638..981f6135795138 100644
--- a/block/bdev.c
+++ b/block/bdev.c
@@ -683,9 +683,6 @@  static int blkdev_get_part(struct block_device *part, fmode_t mode)
 	struct gendisk *disk = part->bd_disk;
 	int ret;
 
-	if (atomic_read(&part->bd_openers))
-		goto done;
-
 	ret = blkdev_get_whole(bdev_whole(part), mode);
 	if (ret)
 		return ret;
@@ -694,9 +691,10 @@  static int blkdev_get_part(struct block_device *part, fmode_t mode)
 	if (!bdev_nr_sectors(part))
 		goto out_blkdev_put;
 
-	disk->open_partitions++;
-	set_init_blocksize(part);
-done:
+	if (!atomic_read(&part->bd_openers)) {
+		disk->open_partitions++;
+		set_init_blocksize(part);
+	}
 	atomic_inc(&part->bd_openers);
 	return 0;
 
@@ -709,10 +707,10 @@  static void blkdev_put_part(struct block_device *part, fmode_t mode)
 {
 	struct block_device *whole = bdev_whole(part);
 
-	if (!atomic_dec_and_test(&part->bd_openers))
-		return;
-	blkdev_flush_mapping(part);
-	whole->bd_disk->open_partitions--;
+	if (atomic_dec_and_test(&part->bd_openers)) {
+		blkdev_flush_mapping(part);
+		whole->bd_disk->open_partitions--;
+	}
 	blkdev_put_whole(whole, mode);
 }