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block: move bd_mutex to struct gendisk

Browse source 
Replace the per-block device bd_mutex with a per-gendisk open_mutex,
thus simplifying locking wherever we deal with partitions.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Ming Lei <ming.lei@redhat.com>
Acked-by: Roger Pau Monné <roger.pau@citrix.com>
Link: https://lore.kernel.org/r/20210525061301.2242282-4-hch@lst.de
Signed-off-by: Jens Axboe <axboe@kernel.dk>
This commit is contained in:
Christoph Hellwig 2021-05-25 08:12:56 +02:00 committed by Jens Axboe
parent 210a6d756f
commit a8698707a1
15 changed files with 68 additions and 76 deletions
Show stats Download patch file Download diff file Expand all files Collapse all files

2
Documentation/filesystems/locking.rst
View file

@ -480,7 +480,7 @@ prototypes::
locking rules:
======================= ===================
ops bd_mutex
ops open_mutex
======================= ===================
open: yes
release: yes

7
block/genhd.c
View file

@ -591,10 +591,10 @@ void del_gendisk(struct gendisk *disk)
blk_integrity_del(disk);
disk_del_events(disk);
mutex_lock(&disk->part0->bd_mutex);
mutex_lock(&disk->open_mutex);
disk->flags &= ~GENHD_FL_UP;
blk_drop_partitions(disk);
mutex_unlock(&disk->part0->bd_mutex);
mutex_unlock(&disk->open_mutex);
fsync_bdev(disk->part0);
__invalidate_device(disk->part0, true);
@ -1273,6 +1273,7 @@ struct gendisk *__alloc_disk_node(int minors, int node_id)
goto out_free_disk;
disk->node_id = node_id;
mutex_init(&disk->open_mutex);
xa_init(&disk->part_tbl);
if (xa_insert(&disk->part_tbl, 0, disk->part0, GFP_KERNEL))
goto out_destroy_part_tbl;
@ -1525,7 +1526,7 @@ void disk_unblock_events(struct gendisk *disk)
* doesn't clear the events from @disk->ev.
*
* CONTEXT:
* If @mask is non-zero must be called with bdev->bd_mutex held.
* If @mask is non-zero must be called with disk->open_mutex held.
*/
void disk_flush_events(struct gendisk *disk, unsigned int mask)
{

24
block/partitions/core.c
View file

@ -283,7 +283,7 @@ struct device_type part_type = {
};
/*
* Must be called either with bd_mutex held, before a disk can be opened or
* Must be called either with open_mutex held, before a disk can be opened or
* after all disk users are gone.
*/
static void delete_partition(struct block_device *part)
@ -312,7 +312,7 @@ static ssize_t whole_disk_show(struct device *dev,
static DEVICE_ATTR(whole_disk, 0444, whole_disk_show, NULL);
/*
* Must be called either with bd_mutex held, before a disk can be opened or
* Must be called either with open_mutex held, before a disk can be opened or
* after all disk users are gone.
*/
static struct block_device *add_partition(struct gendisk *disk, int partno,
@ -453,15 +453,15 @@ int bdev_add_partition(struct block_device *bdev, int partno,
{
struct block_device *part;
mutex_lock(&bdev->bd_mutex);
mutex_lock(&bdev->bd_disk->open_mutex);
if (partition_overlaps(bdev->bd_disk, start, length, -1)) {
mutex_unlock(&bdev->bd_mutex);
mutex_unlock(&bdev->bd_disk->open_mutex);
return -EBUSY;
}
part = add_partition(bdev->bd_disk, partno, start, length,
ADDPART_FLAG_NONE, NULL);
mutex_unlock(&bdev->bd_mutex);
mutex_unlock(&bdev->bd_disk->open_mutex);
return PTR_ERR_OR_ZERO(part);
}
@ -474,8 +474,7 @@ int bdev_del_partition(struct block_device *bdev, int partno)
if (!part)
return -ENXIO;
mutex_lock(&part->bd_mutex);
mutex_lock_nested(&bdev->bd_mutex, 1);
mutex_lock(&bdev->bd_disk->open_mutex);
ret = -EBUSY;
if (part->bd_openers)
@ -484,8 +483,7 @@ int bdev_del_partition(struct block_device *bdev, int partno)
delete_partition(part);
ret = 0;
out_unlock:
mutex_unlock(&bdev->bd_mutex);
mutex_unlock(&part->bd_mutex);
mutex_unlock(&bdev->bd_disk->open_mutex);
bdput(part);
return ret;
}
@ -500,8 +498,7 @@ int bdev_resize_partition(struct block_device *bdev, int partno,
if (!part)
return -ENXIO;
mutex_lock(&part->bd_mutex);
mutex_lock_nested(&bdev->bd_mutex, 1);
mutex_lock(&bdev->bd_disk->open_mutex);
ret = -EINVAL;
if (start != part->bd_start_sect)
goto out_unlock;
@ -514,8 +511,7 @@ int bdev_resize_partition(struct block_device *bdev, int partno,
ret = 0;
out_unlock:
mutex_unlock(&part->bd_mutex);
mutex_unlock(&bdev->bd_mutex);
mutex_unlock(&bdev->bd_disk->open_mutex);
bdput(part);
return ret;
}
@ -541,7 +537,7 @@ void blk_drop_partitions(struct gendisk *disk)
struct block_device *part;
unsigned long idx;
lockdep_assert_held(&disk->part0->bd_mutex);
lockdep_assert_held(&disk->open_mutex);
xa_for_each_start(&disk->part_tbl, idx, part, 1) {
if (!bdgrab(part))

14
drivers/block/loop.c
View file

@ -652,9 +652,9 @@ static void loop_reread_partitions(struct loop_device *lo,
{
int rc;
mutex_lock(&bdev->bd_mutex);
mutex_lock(&bdev->bd_disk->open_mutex);
rc = bdev_disk_changed(bdev, false);
mutex_unlock(&bdev->bd_mutex);
mutex_unlock(&bdev->bd_disk->open_mutex);
if (rc)
pr_warn("%s: partition scan of loop%d (%s) failed (rc=%d)\n",
__func__, lo->lo_number, lo->lo_file_name, rc);
@ -747,7 +747,7 @@ static int loop_change_fd(struct loop_device *lo, struct block_device *bdev,
mutex_unlock(&lo->lo_mutex);
/*
* We must drop file reference outside of lo_mutex as dropping
* the file ref can take bd_mutex which creates circular locking
* the file ref can take open_mutex which creates circular locking
* dependency.
*/
fput(old_file);
@ -1260,7 +1260,7 @@ static int __loop_clr_fd(struct loop_device *lo, bool release)
mutex_unlock(&lo->lo_mutex);
if (partscan) {
/*
* bd_mutex has been held already in release path, so don't
* open_mutex has been held already in release path, so don't
* acquire it if this function is called in such case.
*
* If the reread partition isn't from release path, lo_refcnt
@ -1268,10 +1268,10 @@ static int __loop_clr_fd(struct loop_device *lo, bool release)
* current holder is released.
*/
if (!release)
mutex_lock(&bdev->bd_mutex);
mutex_lock(&bdev->bd_disk->open_mutex);
err = bdev_disk_changed(bdev, false);
if (!release)
mutex_unlock(&bdev->bd_mutex);
mutex_unlock(&bdev->bd_disk->open_mutex);
if (err)
pr_warn("%s: partition scan of loop%d failed (rc=%d)\n",
__func__, lo_number, err);
@ -1298,7 +1298,7 @@ static int __loop_clr_fd(struct loop_device *lo, bool release)
/*
* Need not hold lo_mutex to fput backing file. Calling fput holding
* lo_mutex triggers a circular lock dependency possibility warning as
* fput can take bd_mutex which is usually taken before lo_mutex.
* fput can take open_mutex which is usually taken before lo_mutex.
*/
if (filp)
fput(filp);

8
drivers/block/xen-blkfront.c
View file

@ -2163,7 +2163,7 @@ static void blkfront_closing(struct blkfront_info *info)
return;
}
mutex_lock(&bdev->bd_mutex);
mutex_lock(&bdev->bd_disk->open_mutex);
if (bdev->bd_openers) {
xenbus_dev_error(xbdev, -EBUSY,
@ -2174,7 +2174,7 @@ static void blkfront_closing(struct blkfront_info *info)
xenbus_frontend_closed(xbdev);
}
mutex_unlock(&bdev->bd_mutex);
mutex_unlock(&bdev->bd_disk->open_mutex);
bdput(bdev);
}
@ -2531,7 +2531,7 @@ static int blkfront_remove(struct xenbus_device *xbdev)
* isn't closed yet, we let release take care of it.
*/
mutex_lock(&bdev->bd_mutex);
mutex_lock(&disk->open_mutex);
info = disk->private_data;
dev_warn(disk_to_dev(disk),
@ -2546,7 +2546,7 @@ static int blkfront_remove(struct xenbus_device *xbdev)
mutex_unlock(&blkfront_mutex);
}
mutex_unlock(&bdev->bd_mutex);
mutex_unlock(&disk->open_mutex);
bdput(bdev);
return 0;

18
drivers/block/zram/zram_drv.c
View file

@ -1781,24 +1781,24 @@ static ssize_t reset_store(struct device *dev,
zram = dev_to_zram(dev);
bdev = zram->disk->part0;
mutex_lock(&bdev->bd_mutex);
mutex_lock(&bdev->bd_disk->open_mutex);
/* Do not reset an active device or claimed device */
if (bdev->bd_openers || zram->claim) {
mutex_unlock(&bdev->bd_mutex);
mutex_unlock(&bdev->bd_disk->open_mutex);
return -EBUSY;
}
/* From now on, anyone can't open /dev/zram[0-9] */
zram->claim = true;
mutex_unlock(&bdev->bd_mutex);
mutex_unlock(&bdev->bd_disk->open_mutex);
/* Make sure all the pending I/O are finished */
fsync_bdev(bdev);
zram_reset_device(zram);
mutex_lock(&bdev->bd_mutex);
mutex_lock(&bdev->bd_disk->open_mutex);
zram->claim = false;
mutex_unlock(&bdev->bd_mutex);
mutex_unlock(&bdev->bd_disk->open_mutex);
return len;
}
@ -1808,7 +1808,7 @@ static int zram_open(struct block_device *bdev, fmode_t mode)
int ret = 0;
struct zram *zram;
WARN_ON(!mutex_is_locked(&bdev->bd_mutex));
WARN_ON(!mutex_is_locked(&bdev->bd_disk->open_mutex));
zram = bdev->bd_disk->private_data;
/* zram was claimed to reset so open request fails */
@ -1972,14 +1972,14 @@ static int zram_remove(struct zram *zram)
{
struct block_device *bdev = zram->disk->part0;
mutex_lock(&bdev->bd_mutex);
mutex_lock(&bdev->bd_disk->open_mutex);
if (bdev->bd_openers || zram->claim) {
mutex_unlock(&bdev->bd_mutex);
mutex_unlock(&bdev->bd_disk->open_mutex);
return -EBUSY;
}
zram->claim = true;
mutex_unlock(&bdev->bd_mutex);
mutex_unlock(&bdev->bd_disk->open_mutex);
zram_debugfs_unregister(zram);

2
drivers/block/zram/zram_drv.h
View file

@ -112,7 +112,7 @@ struct zram {
/*
* zram is claimed so open request will be failed
*/
bool claim; /* Protected by bdev->bd_mutex */
bool claim; /* Protected by disk->open_mutex */
struct file *backing_dev;
#ifdef CONFIG_ZRAM_WRITEBACK
spinlock_t wb_limit_lock;

6
drivers/md/md.h
View file

@ -395,10 +395,10 @@ struct mddev {
* that we are never stopping an array while it is open.
* 'reconfig_mutex' protects all other reconfiguration.
* These locks are separate due to conflicting interactions
* with bdev->bd_mutex.
* with disk->open_mutex.
* Lock ordering is:
* reconfig_mutex -> bd_mutex
* bd_mutex -> open_mutex: e.g. __blkdev_get -> md_open
* reconfig_mutex -> disk->open_mutex
* disk->open_mutex -> open_mutex: e.g. __blkdev_get -> md_open
*/
struct mutex open_mutex;
struct mutex reconfig_mutex;

8
drivers/s390/block/dasd_genhd.c
View file

@ -109,9 +109,9 @@ int dasd_scan_partitions(struct dasd_block *block)
return -ENODEV;
}
mutex_lock(&bdev->bd_mutex);
mutex_lock(&block->gdp->open_mutex);
rc = bdev_disk_changed(bdev, false);
mutex_unlock(&bdev->bd_mutex);
mutex_unlock(&block->gdp->open_mutex);
if (rc)
DBF_DEV_EVENT(DBF_ERR, block->base,
"scan partitions error, rc %d", rc);
@ -145,9 +145,9 @@ void dasd_destroy_partitions(struct dasd_block *block)
bdev = block->bdev;
block->bdev = NULL;
mutex_lock(&bdev->bd_mutex);
mutex_lock(&bdev->bd_disk->open_mutex);
bdev_disk_changed(bdev, true);
mutex_unlock(&bdev->bd_mutex);
mutex_unlock(&bdev->bd_disk->open_mutex);
/* Matching blkdev_put to the blkdev_get in dasd_scan_partitions. */
blkdev_put(bdev, FMODE_READ);

4
drivers/scsi/sd.c
View file

@ -1400,7 +1400,7 @@ static void sd_uninit_command(struct scsi_cmnd *SCpnt)
* In the latter case @inode and @filp carry an abridged amount
* of information as noted above.
*
* Locking: called with bdev->bd_mutex held.
* Locking: called with bdev->bd_disk->open_mutex held.
**/
static int sd_open(struct block_device *bdev, fmode_t mode)
{
@ -1476,7 +1476,7 @@ static int sd_open(struct block_device *bdev, fmode_t mode)
* Note: may block (uninterruptible) if error recovery is underway
* on this disk.
*
* Locking: called with bdev->bd_mutex held.
* Locking: called with bdev->bd_disk->open_mutex held.
**/
static void sd_release(struct gendisk *disk, fmode_t mode)
{

37
fs/block_dev.c
View file

@ -895,7 +895,6 @@ struct block_device *bdev_alloc(struct gendisk *disk, u8 partno)
mapping_set_gfp_mask(&inode->i_data, GFP_USER);
bdev = I_BDEV(inode);
mutex_init(&bdev->bd_mutex);
mutex_init(&bdev->bd_fsfreeze_mutex);
spin_lock_init(&bdev->bd_size_lock);
bdev->bd_disk = disk;
@ -1154,7 +1153,7 @@ int bd_link_disk_holder(struct block_device *bdev, struct gendisk *disk)
struct bd_holder_disk *holder;
int ret = 0;
mutex_lock(&bdev->bd_mutex);
mutex_lock(&bdev->bd_disk->open_mutex);
WARN_ON_ONCE(!bdev->bd_holder);
@ -1199,7 +1198,7 @@ int bd_link_disk_holder(struct block_device *bdev, struct gendisk *disk)
out_free:
kfree(holder);
out_unlock:
mutex_unlock(&bdev->bd_mutex);
mutex_unlock(&bdev->bd_disk->open_mutex);
return ret;
}
EXPORT_SYMBOL_GPL(bd_link_disk_holder);
@ -1218,7 +1217,7 @@ void bd_unlink_disk_holder(struct block_device *bdev, struct gendisk *disk)
{
struct bd_holder_disk *holder;
mutex_lock(&bdev->bd_mutex);
mutex_lock(&bdev->bd_disk->open_mutex);
holder = bd_find_holder_disk(bdev, disk);
@ -1230,7 +1229,7 @@ void bd_unlink_disk_holder(struct block_device *bdev, struct gendisk *disk)
kfree(holder);
}
mutex_unlock(&bdev->bd_mutex);
mutex_unlock(&bdev->bd_disk->open_mutex);
}
EXPORT_SYMBOL_GPL(bd_unlink_disk_holder);
#endif
@ -1242,7 +1241,7 @@ int bdev_disk_changed(struct block_device *bdev, bool invalidate)
struct gendisk *disk = bdev->bd_disk;
int ret = 0;
lockdep_assert_held(&bdev->bd_mutex);
lockdep_assert_held(&disk->open_mutex);
if (!(disk->flags & GENHD_FL_UP))
return -ENXIO;
@ -1327,14 +1326,10 @@ static int blkdev_get_part(struct block_device *part, fmode_t mode)
goto done;
whole = bdgrab(disk->part0);
mutex_lock_nested(&whole->bd_mutex, 1);
ret = blkdev_get_whole(whole, mode);
if (ret) {
mutex_unlock(&whole->bd_mutex);
if (ret)
goto out_put_whole;
}
whole->bd_part_count++;
mutex_unlock(&whole->bd_mutex);
ret = -ENXIO;
if (!bdev_nr_sectors(part))
@ -1437,7 +1432,7 @@ struct block_device *blkdev_get_by_dev(dev_t dev, fmode_t mode, void *holder)
disk_block_events(disk);
mutex_lock(&bdev->bd_mutex);
mutex_lock(&disk->open_mutex);
ret = -ENXIO;
if (!(disk->flags & GENHD_FL_UP))
goto abort_claiming;
@ -1463,7 +1458,7 @@ struct block_device *blkdev_get_by_dev(dev_t dev, fmode_t mode, void *holder)
unblock_events = false;
}
}
mutex_unlock(&bdev->bd_mutex);
mutex_unlock(&disk->open_mutex);
if (unblock_events)
disk_unblock_events(disk);
@ -1472,7 +1467,7 @@ struct block_device *blkdev_get_by_dev(dev_t dev, fmode_t mode, void *holder)
abort_claiming:
if (mode & FMODE_EXCL)
bd_abort_claiming(bdev, holder);
mutex_unlock(&bdev->bd_mutex);
mutex_unlock(&disk->open_mutex);
disk_unblock_events(disk);
put_blkdev:
blkdev_put_no_open(bdev);
@ -1552,7 +1547,6 @@ static void __blkdev_put(struct block_device *bdev, fmode_t mode, int for_part)
struct gendisk *disk = bdev->bd_disk;
struct block_device *victim = NULL;
mutex_lock_nested(&bdev->bd_mutex, for_part);
if (for_part)
bdev->bd_part_count--;
@ -1567,7 +1561,6 @@ static void __blkdev_put(struct block_device *bdev, fmode_t mode, int for_part)
if (!bdev_is_partition(bdev) && disk->fops->release)
disk->fops->release(disk, mode);
mutex_unlock(&bdev->bd_mutex);
if (victim) {
__blkdev_put(victim, mode, 1);
bdput(victim);
@ -1588,15 +1581,14 @@ void blkdev_put(struct block_device *bdev, fmode_t mode)
if (bdev->bd_openers == 1)
sync_blockdev(bdev);
mutex_lock(&bdev->bd_mutex);
mutex_lock(&disk->open_mutex);
if (mode & FMODE_EXCL) {
struct block_device *whole = bdev_whole(bdev);
bool bdev_free;
/*
* Release a claim on the device. The holder fields
* are protected with bdev_lock. bd_mutex is to
* are protected with bdev_lock. open_mutex is to
* synchronize disk_holder unlinking.
*/
spin_lock(&bdev_lock);
@ -1627,9 +1619,10 @@ void blkdev_put(struct block_device *bdev, fmode_t mode)
* from userland - e.g. eject(1).
*/
disk_flush_events(disk, DISK_EVENT_MEDIA_CHANGE);
mutex_unlock(&bdev->bd_mutex);
__blkdev_put(bdev, mode, 0);
mutex_unlock(&disk->open_mutex);
blkdev_put_no_open(bdev);
}
EXPORT_SYMBOL(blkdev_put);
@ -1936,10 +1929,10 @@ void iterate_bdevs(void (*func)(struct block_device *, void *), void *arg)
old_inode = inode;
bdev = I_BDEV(inode);
mutex_lock(&bdev->bd_mutex);
mutex_lock(&bdev->bd_disk->open_mutex);
if (bdev->bd_openers)
func(bdev, arg);
mutex_unlock(&bdev->bd_mutex);
mutex_unlock(&bdev->bd_disk->open_mutex);
spin_lock(&blockdev_superblock->s_inode_list_lock);
}

2
fs/btrfs/volumes.c
View file

@ -1247,7 +1247,7 @@ int btrfs_open_devices(struct btrfs_fs_devices *fs_devices,
lockdep_assert_held(&uuid_mutex);
/*
* The device_list_mutex cannot be taken here in case opening the
* underlying device takes further locks like bd_mutex.
* underlying device takes further locks like open_mutex.
*
* We also don't need the lock here as this is called during mount and
* exclusion is provided by uuid_mutex

8
fs/super.c
View file

@ -1277,9 +1277,9 @@ int get_tree_bdev(struct fs_context *fc,
}
/*
* s_umount nests inside bd_mutex during
* s_umount nests inside open_mutex during
* __invalidate_device(). blkdev_put() acquires
* bd_mutex and can't be called under s_umount. Drop
* open_mutex and can't be called under s_umount. Drop
* s_umount temporarily. This is safe as we're
* holding an active reference.
*/
@ -1352,9 +1352,9 @@ struct dentry *mount_bdev(struct file_system_type *fs_type,
}
/*
* s_umount nests inside bd_mutex during
* s_umount nests inside open_mutex during
* __invalidate_device(). blkdev_put() acquires
* bd_mutex and can't be called under s_umount. Drop
* open_mutex and can't be called under s_umount. Drop
* s_umount temporarily. This is safe as we're
* holding an active reference.
*/

1
include/linux/blk_types.h
View file

@ -29,7 +29,6 @@ struct block_device {
int bd_openers;
struct inode * bd_inode; /* will die */
struct super_block * bd_super;
struct mutex bd_mutex; /* open/close mutex */
void * bd_claiming;
struct device bd_device;
void * bd_holder;

3
include/linux/genhd.h
View file

@ -154,6 +154,9 @@ struct gendisk {
#define GD_NEED_PART_SCAN 0
#define GD_READ_ONLY 1
#define GD_QUEUE_REF 2
struct mutex open_mutex; /* open/close mutex */
struct kobject *slave_dir;
struct timer_rand_state *random;