[PATCH v3 0/2] loop: replace kill_bdev with invalidate_bdev

[PATCH v3 0/2] loop: replace kill_bdev with invalidate_bdev

[Zheng Bin]

v1->v2: modify comment, and make function 'kill_bdev' static
v2->v3: adapt code for commit 0c3796c24459
("loop: Factor out configuring loop from status")

Zheng Bin (2):
  loop: replace kill_bdev with invalidate_bdev
  block: make function 'kill_bdev' static

 drivers/block/loop.c | 8 ++++----
 fs/block_dev.c       | 5 ++---
 include/linux/fs.h   | 2 --
 3 files changed, 6 insertions(+), 9 deletions(-)

--
2.25.4

[PATCH v3 1/2] loop: replace kill_bdev with invalidate_bdev

[Zheng Bin]

When a filesystem is mounted on a loop device and on a loop ioctl
LOOP_SET_STATUS64, because of kill_bdev, buffer_head mappings are getting
destroyed.
kill_bdev
  truncate_inode_pages
    truncate_inode_pages_range
      do_invalidatepage
        block_invalidatepage
          discard_buffer  -->clear BH_Mapped flag

sb_bread
  __bread_gfp
  bh = __getblk_gfp
  -->discard_buffer clear BH_Mapped flag
  __bread_slow
    submit_bh
      submit_bh_wbc
        BUG_ON(!buffer_mapped(bh))  --> hit this BUG_ON

Fixes: 5db470e229e2 ("loop: drop caches if offset or block_size are changed")
Signed-off-by: Zheng Bin <zhengbin13@huawei.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Bart Van Assche <bvanassche@acm.org>
---
 drivers/block/loop.c | 8 ++++----
 1 file changed, 4 insertions(+), 4 deletions(-)

diff --git a/drivers/block/loop.c b/drivers/block/loop.c
index c33bbbfd1bd9..475e1a738560 100644
--- a/drivers/block/loop.c
+++ b/drivers/block/loop.c
@@ -1368,14 +1368,14 @@ loop_set_status(struct loop_device *lo, const struct loop_info64 *info)
 	    lo->lo_sizelimit != info->lo_sizelimit) {
 		size_changed = true;
 		sync_blockdev(lo->lo_device);
-		kill_bdev(lo->lo_device);
+		invalidate_bdev(lo->lo_device);
 	}

 	/* I/O need to be drained during transfer transition */
 	blk_mq_freeze_queue(lo->lo_queue);

 	if (size_changed && lo->lo_device->bd_inode->i_mapping->nrpages) {
-		/* If any pages were dirtied after kill_bdev(), try again */
+		/* If any pages were dirtied after invalidate_bdev(), try again */
 		err = -EAGAIN;
 		pr_warn("%s: loop%d (%s) has still dirty pages (nrpages=%lu)\n",
 			__func__, lo->lo_number, lo->lo_file_name,
@@ -1615,11 +1615,11 @@ static int loop_set_block_size(struct loop_device *lo, unsigned long arg)
 		return 0;

 	sync_blockdev(lo->lo_device);
-	kill_bdev(lo->lo_device);
+	invalidate_bdev(lo->lo_device);

 	blk_mq_freeze_queue(lo->lo_queue);

-	/* kill_bdev should have truncated all the pages */
+	/* invalidate_bdev should have truncated all the pages */
 	if (lo->lo_device->bd_inode->i_mapping->nrpages) {
 		err = -EAGAIN;
 		pr_warn("%s: loop%d (%s) has still dirty pages (nrpages=%lu)\n",
--
2.25.4

[PATCH v3 2/2] block: make function 'kill_bdev' static

[Zheng Bin]

kill_bdev does not have any external user, so make it static.

Signed-off-by: Zheng Bin <zhengbin13@huawei.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Bart Van Assche <bvanassche@acm.org>
---
 fs/block_dev.c     | 5 ++---
 include/linux/fs.h | 2 --
 2 files changed, 2 insertions(+), 5 deletions(-)

diff --git a/fs/block_dev.c b/fs/block_dev.c
index 47860e589388..0137ed31d58d 100644
--- a/fs/block_dev.c
+++ b/fs/block_dev.c
@@ -75,7 +75,7 @@ static void bdev_write_inode(struct block_device *bdev)
 }

 /* Kill _all_ buffers and pagecache , dirty or not.. */
-void kill_bdev(struct block_device *bdev)
+static void kill_bdev(struct block_device *bdev)
 {
 	struct address_space *mapping = bdev->bd_inode->i_mapping;

@@ -84,8 +84,7 @@ void kill_bdev(struct block_device *bdev)

 	invalidate_bh_lrus();
 	truncate_inode_pages(mapping, 0);
-}	
-EXPORT_SYMBOL(kill_bdev);
+}

 /* Invalidate clean unused buffers and pagecache. */
 void invalidate_bdev(struct block_device *bdev)
diff --git a/include/linux/fs.h b/include/linux/fs.h
index 2e675c075694..f5bb1efc0c45 100644
--- a/include/linux/fs.h
+++ b/include/linux/fs.h
@@ -2609,7 +2609,6 @@ extern void bdput(struct block_device *);
 extern void invalidate_bdev(struct block_device *);
 extern void iterate_bdevs(void (*)(struct block_device *, void *), void *);
 extern int sync_blockdev(struct block_device *bdev);
-extern void kill_bdev(struct block_device *);
 extern struct super_block *freeze_bdev(struct block_device *);
 extern void emergency_thaw_all(void);
 extern void emergency_thaw_bdev(struct super_block *sb);
@@ -2625,7 +2624,6 @@ static inline bool sb_is_blkdev_sb(struct super_block *sb)
 #else
 static inline void bd_forget(struct inode *inode) {}
 static inline int sync_blockdev(struct block_device *bdev) { return 0; }
-static inline void kill_bdev(struct block_device *bdev) {}
 static inline void invalidate_bdev(struct block_device *bdev) {}

 static inline struct super_block *freeze_bdev(struct block_device *sb)
--
2.25.4

Re: [PATCH v3 0/2] loop: replace kill_bdev with invalidate_bdev

[Jens Axboe]

On 6/17/20 10:21 PM, Zheng Bin wrote:
> v1->v2: modify comment, and make function 'kill_bdev' static
> v2->v3: adapt code for commit 0c3796c24459
> ("loop: Factor out configuring loop from status")
> 
> Zheng Bin (2):
>   loop: replace kill_bdev with invalidate_bdev
>   block: make function 'kill_bdev' static
> 
>  drivers/block/loop.c | 8 ++++----
>  fs/block_dev.c       | 5 ++---
>  include/linux/fs.h   | 2 --
>  3 files changed, 6 insertions(+), 9 deletions(-)

Applied, thanks.

-- 
Jens Axboe