From: Christoph Hellwig <hch@lst.de>
To: Jens Axboe <axboe@kernel.dk>
Cc: Josef Bacik <josef@toxicpanda.com>,
David Sterba <dsterba@suse.com>,
Naohiro Aota <naohiro.aota@wdc.com>,
linux-block@vger.kernel.org, linux-btrfs@vger.kernel.org
Subject: [PATCH 06/10] block: change the refcounting for partitions
Date: Sat, 24 Jul 2021 09:12:45 +0200 [thread overview]
Message-ID: <20210724071249.1284585-7-hch@lst.de> (raw)
In-Reply-To: <20210724071249.1284585-1-hch@lst.de>
Instead of acquiring an inode reference on open make sure partitions
always hold device model references to the disk while alive, and switch
open to grab only a device model reference to the opened block device.
If that is a partition the disk reference is transitively held by the
partition already.
---
block/partitions/core.c | 4 +++
fs/block_dev.c | 60 ++++++++++++++++-------------------------
2 files changed, 27 insertions(+), 37 deletions(-)
diff --git a/block/partitions/core.c b/block/partitions/core.c
index ae88b5439056..1b02073a2047 100644
--- a/block/partitions/core.c
+++ b/block/partitions/core.c
@@ -261,6 +261,7 @@ static void part_release(struct device *dev)
{
if (MAJOR(dev->devt) == BLOCK_EXT_MAJOR)
blk_free_ext_minor(MINOR(dev->devt));
+ put_disk(dev_to_bdev(dev)->bd_disk);
bdput(dev_to_bdev(dev));
}
@@ -364,6 +365,9 @@ static struct block_device *add_partition(struct gendisk *disk, int partno,
pdev->type = &part_type;
pdev->parent = ddev;
+ /* ensure we always have a reference to the whole disk */
+ get_device(disk_to_dev(disk));
+
/* in consecutive minor range? */
if (bdev->bd_partno < disk->minors) {
devt = MKDEV(disk->major, disk->first_minor + bdev->bd_partno);
diff --git a/fs/block_dev.c b/fs/block_dev.c
index 932f4034ad66..4a6c8c0a3bc9 100644
--- a/fs/block_dev.c
+++ b/fs/block_dev.c
@@ -921,16 +921,6 @@ void bdev_add(struct block_device *bdev, dev_t dev)
insert_inode_hash(bdev->bd_inode);
}
-static struct block_device *bdget(dev_t dev)
-{
- struct inode *inode;
-
- inode = ilookup(blockdev_superblock, dev);
- if (!inode)
- return NULL;
- return &BDEV_I(inode)->bdev;
-}
-
/**
* bdgrab -- Grab a reference to an already referenced block device
* @bdev: Block device to grab a reference to.
@@ -1282,16 +1272,14 @@ static void blkdev_put_whole(struct block_device *bdev, fmode_t mode)
static int blkdev_get_part(struct block_device *part, fmode_t mode)
{
struct gendisk *disk = part->bd_disk;
- struct block_device *whole;
int ret;
if (part->bd_openers)
goto done;
- whole = bdgrab(disk->part0);
- ret = blkdev_get_whole(whole, mode);
+ ret = blkdev_get_whole(bdev_whole(part), mode);
if (ret)
- goto out_put_whole;
+ return ret;
ret = -ENXIO;
if (!bdev_nr_sectors(part))
@@ -1306,9 +1294,7 @@ static int blkdev_get_part(struct block_device *part, fmode_t mode)
return 0;
out_blkdev_put:
- blkdev_put_whole(whole, mode);
-out_put_whole:
- bdput(whole);
+ blkdev_put_whole(bdev_whole(part), mode);
return ret;
}
@@ -1321,42 +1307,42 @@ static void blkdev_put_part(struct block_device *part, fmode_t mode)
blkdev_flush_mapping(part);
whole->bd_disk->open_partitions--;
blkdev_put_whole(whole, mode);
- bdput(whole);
}
struct block_device *blkdev_get_no_open(dev_t dev)
{
struct block_device *bdev;
- struct gendisk *disk;
+ struct inode *inode;
- bdev = bdget(dev);
- if (!bdev) {
+ inode = ilookup(blockdev_superblock, dev);
+ if (!inode) {
blk_request_module(dev);
- bdev = bdget(dev);
- if (!bdev)
+ inode = ilookup(blockdev_superblock, dev);
+ if (!inode)
return NULL;
}
- disk = bdev->bd_disk;
- if (!kobject_get_unless_zero(&disk_to_dev(disk)->kobj))
- goto bdput;
- if (disk->flags & GENHD_FL_HIDDEN)
- goto put_disk;
- if (!try_module_get(bdev->bd_disk->fops->owner))
- goto put_disk;
+ /* switch from the inode reference to a device mode one: */
+ bdev = &BDEV_I(inode)->bdev;
+ if (!kobject_get_unless_zero(&bdev->bd_device.kobj))
+ bdev = NULL;
+ iput(inode);
+
+ if (!bdev)
+ return NULL;
+ if ((bdev->bd_disk->flags & GENHD_FL_HIDDEN) ||
+ !try_module_get(bdev->bd_disk->fops->owner)) {
+ put_device(&bdev->bd_device);
+ return NULL;
+ }
+
return bdev;
-put_disk:
- put_disk(disk);
-bdput:
- bdput(bdev);
- return NULL;
}
void blkdev_put_no_open(struct block_device *bdev)
{
module_put(bdev->bd_disk->fops->owner);
- put_disk(bdev->bd_disk);
- bdput(bdev);
+ put_device(&bdev->bd_device);
}
/**
--
2.30.2
next prev parent reply other threads:[~2021-07-24 7:15 UTC|newest]
Thread overview: 18+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-07-24 7:12 fixes and cleanups for block_device refcounting v3 Christoph Hellwig
2021-07-24 7:12 ` [PATCH 01/10] block: delay freeing the gendisk Christoph Hellwig
2021-07-24 7:12 ` [PATCH 02/10] block: assert the locking state in delete_partition Christoph Hellwig
2021-07-24 7:12 ` [PATCH 03/10] block: unhash the block device inodes earlier Christoph Hellwig
2021-07-26 10:15 ` Ming Lei
2021-07-24 7:12 ` [PATCH 04/10] block: remove the GENHD_FL_UP check in blkdev_get_no_open Christoph Hellwig
2021-07-26 10:16 ` Ming Lei
2021-07-24 7:12 ` [PATCH 05/10] block: allocate bd_meta_info later in add_partitions Christoph Hellwig
2021-07-24 7:12 ` Christoph Hellwig [this message]
2021-07-26 2:20 ` [PATCH 06/10] block: change the refcounting for partitions Damien Le Moal
2021-07-26 10:17 ` Ming Lei
2021-07-24 7:12 ` [PATCH 07/10] btrfs: store a block_device in struct btrfs_ordered_extent Christoph Hellwig
2021-07-24 7:12 ` [PATCH 08/10] loop: don't grab a reference to the block device Christoph Hellwig
2021-07-24 7:12 ` [PATCH 09/10] block: remove bdgrab Christoph Hellwig
2021-07-24 7:12 ` [PATCH 10/10] block: remove bdput Christoph Hellwig
2021-07-24 7:22 ` fixes and cleanups for block_device refcounting v3 Christoph Hellwig
2021-07-24 16:06 ` Jens Axboe
2021-07-24 16:54 ` Christoph Hellwig
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