* [PATCH v2 1/2] block: introduce zone capacity helper
2025-03-18 0:59 [PATCH v2 0/2] btrfs: zoned: skip reporting zone for new block group Naohiro Aota
@ 2025-03-18 0:59 ` Naohiro Aota
2025-03-18 5:14 ` Damien Le Moal
2025-03-18 7:27 ` Johannes Thumshirn
2025-03-18 0:59 ` [PATCH v2 2/2] btrfs: zoned: skip reporting zone for new block group Naohiro Aota
1 sibling, 2 replies; 9+ messages in thread
From: Naohiro Aota @ 2025-03-18 0:59 UTC (permalink / raw)
To: linux-btrfs; +Cc: dlemoal, axboe, linux-block, hch, Naohiro Aota
{bdev,disk}_zone_capacity() takes block_device or gendisk and sector position
and returns the zone capacity of the corresponding zone.
With that, move disk_nr_zones() and blk_zone_plug_bio() to consolidate them in
the same #ifdef block.
Signed-off-by: Naohiro Aota <naohiro.aota@wdc.com>
---
include/linux/blkdev.h | 67 ++++++++++++++++++++++++++++--------------
1 file changed, 45 insertions(+), 22 deletions(-)
diff --git a/include/linux/blkdev.h b/include/linux/blkdev.h
index d37751789bf5..6f1bdec27ac7 100644
--- a/include/linux/blkdev.h
+++ b/include/linux/blkdev.h
@@ -691,23 +691,6 @@ static inline bool blk_queue_is_zoned(struct request_queue *q)
(q->limits.features & BLK_FEAT_ZONED);
}
-#ifdef CONFIG_BLK_DEV_ZONED
-static inline unsigned int disk_nr_zones(struct gendisk *disk)
-{
- return disk->nr_zones;
-}
-bool blk_zone_plug_bio(struct bio *bio, unsigned int nr_segs);
-#else /* CONFIG_BLK_DEV_ZONED */
-static inline unsigned int disk_nr_zones(struct gendisk *disk)
-{
- return 0;
-}
-static inline bool blk_zone_plug_bio(struct bio *bio, unsigned int nr_segs)
-{
- return false;
-}
-#endif /* CONFIG_BLK_DEV_ZONED */
-
static inline unsigned int disk_zone_no(struct gendisk *disk, sector_t sector)
{
if (!blk_queue_is_zoned(disk->queue))
@@ -715,11 +698,6 @@ static inline unsigned int disk_zone_no(struct gendisk *disk, sector_t sector)
return sector >> ilog2(disk->queue->limits.chunk_sectors);
}
-static inline unsigned int bdev_nr_zones(struct block_device *bdev)
-{
- return disk_nr_zones(bdev->bd_disk);
-}
-
static inline unsigned int bdev_max_open_zones(struct block_device *bdev)
{
return bdev->bd_disk->queue->limits.max_open_zones;
@@ -826,6 +804,51 @@ static inline u64 sb_bdev_nr_blocks(struct super_block *sb)
(sb->s_blocksize_bits - SECTOR_SHIFT);
}
+#ifdef CONFIG_BLK_DEV_ZONED
+static inline unsigned int disk_nr_zones(struct gendisk *disk)
+{
+ return disk->nr_zones;
+}
+bool blk_zone_plug_bio(struct bio *bio, unsigned int nr_segs);
+
+/**
+ * disk_zone_capacity - returns the zone capacity of zone at @pos
+ * @disk: disk to work with
+ * @pos: sector number within the querying zone
+ *
+ * Returns the zone capacity of a zone at @pos. @pos can be any sector contained
+ * in the zone.
+ */
+static inline unsigned int disk_zone_capacity(struct gendisk *disk,
+ sector_t pos)
+{
+ sector_t zone_sectors = disk->queue->limits.chunk_sectors;
+
+ if (pos + zone_sectors >= get_capacity(disk))
+ return disk->last_zone_capacity;
+ return disk->zone_capacity;
+}
+static inline unsigned int bdev_zone_capacity(struct block_device *bdev,
+ sector_t pos)
+{
+ return disk_zone_capacity(bdev->bd_disk, pos);
+}
+#else /* CONFIG_BLK_DEV_ZONED */
+static inline unsigned int disk_nr_zones(struct gendisk *disk)
+{
+ return 0;
+}
+static inline bool blk_zone_plug_bio(struct bio *bio, unsigned int nr_segs)
+{
+ return false;
+}
+#endif /* CONFIG_BLK_DEV_ZONED */
+
+static inline unsigned int bdev_nr_zones(struct block_device *bdev)
+{
+ return disk_nr_zones(bdev->bd_disk);
+}
+
int bdev_disk_changed(struct gendisk *disk, bool invalidate);
void put_disk(struct gendisk *disk);
--
2.49.0
^ permalink raw reply related [flat|nested] 9+ messages in thread* [PATCH v2 2/2] btrfs: zoned: skip reporting zone for new block group
2025-03-18 0:59 [PATCH v2 0/2] btrfs: zoned: skip reporting zone for new block group Naohiro Aota
2025-03-18 0:59 ` [PATCH v2 1/2] block: introduce zone capacity helper Naohiro Aota
@ 2025-03-18 0:59 ` Naohiro Aota
2025-03-18 7:25 ` Johannes Thumshirn
1 sibling, 1 reply; 9+ messages in thread
From: Naohiro Aota @ 2025-03-18 0:59 UTC (permalink / raw)
To: linux-btrfs
Cc: dlemoal, axboe, linux-block, hch, Naohiro Aota,
Shin'ichiro Kawasaki
There is a potential deadlock if we do report zones in an IO context, detailed
in below lockdep report. When one process do a report zones and another process
freezes the block device, the report zones side cannot allocate a tag because
the freeze is already started. This can thus result in new block group creation
to hang forever, blocking the write path.
Thankfully, a new block group should be created on empty zones. So, reporting
the zones is not necessary and we can set the write pointer = 0 and load the
zone capacity from the block layer using bdev_zone_capacity() helper.
======================================================
WARNING: possible circular locking dependency detected
6.14.0-rc1 #252 Not tainted
------------------------------------------------------
modprobe/1110 is trying to acquire lock:
ffff888100ac83e0 ((work_completion)(&(&wb->dwork)->work)){+.+.}-{0:0}, at: __flush_work+0x38f/0xb60
but task is already holding lock:
ffff8881205b6f20 (&q->q_usage_counter(queue)#16){++++}-{0:0}, at: sd_remove+0x85/0x130
which lock already depends on the new lock.
the existing dependency chain (in reverse order) is:
-> #3 (&q->q_usage_counter(queue)#16){++++}-{0:0}:
blk_queue_enter+0x3d9/0x500
blk_mq_alloc_request+0x47d/0x8e0
scsi_execute_cmd+0x14f/0xb80
sd_zbc_do_report_zones+0x1c1/0x470
sd_zbc_report_zones+0x362/0xd60
blkdev_report_zones+0x1b1/0x2e0
btrfs_get_dev_zones+0x215/0x7e0 [btrfs]
btrfs_load_block_group_zone_info+0x6d2/0x2c10 [btrfs]
btrfs_make_block_group+0x36b/0x870 [btrfs]
btrfs_create_chunk+0x147d/0x2320 [btrfs]
btrfs_chunk_alloc+0x2ce/0xcf0 [btrfs]
start_transaction+0xce6/0x1620 [btrfs]
btrfs_uuid_scan_kthread+0x4ee/0x5b0 [btrfs]
kthread+0x39d/0x750
ret_from_fork+0x30/0x70
ret_from_fork_asm+0x1a/0x30
-> #2 (&fs_info->dev_replace.rwsem){++++}-{4:4}:
down_read+0x9b/0x470
btrfs_map_block+0x2ce/0x2ce0 [btrfs]
btrfs_submit_chunk+0x2d4/0x16c0 [btrfs]
btrfs_submit_bbio+0x16/0x30 [btrfs]
btree_write_cache_pages+0xb5a/0xf90 [btrfs]
do_writepages+0x17f/0x7b0
__writeback_single_inode+0x114/0xb00
writeback_sb_inodes+0x52b/0xe00
wb_writeback+0x1a7/0x800
wb_workfn+0x12a/0xbd0
process_one_work+0x85a/0x1460
worker_thread+0x5e2/0xfc0
kthread+0x39d/0x750
ret_from_fork+0x30/0x70
ret_from_fork_asm+0x1a/0x30
-> #1 (&fs_info->zoned_meta_io_lock){+.+.}-{4:4}:
__mutex_lock+0x1aa/0x1360
btree_write_cache_pages+0x252/0xf90 [btrfs]
do_writepages+0x17f/0x7b0
__writeback_single_inode+0x114/0xb00
writeback_sb_inodes+0x52b/0xe00
wb_writeback+0x1a7/0x800
wb_workfn+0x12a/0xbd0
process_one_work+0x85a/0x1460
worker_thread+0x5e2/0xfc0
kthread+0x39d/0x750
ret_from_fork+0x30/0x70
ret_from_fork_asm+0x1a/0x30
-> #0 ((work_completion)(&(&wb->dwork)->work)){+.+.}-{0:0}:
__lock_acquire+0x2f52/0x5ea0
lock_acquire+0x1b1/0x540
__flush_work+0x3ac/0xb60
wb_shutdown+0x15b/0x1f0
bdi_unregister+0x172/0x5b0
del_gendisk+0x841/0xa20
sd_remove+0x85/0x130
device_release_driver_internal+0x368/0x520
bus_remove_device+0x1f1/0x3f0
device_del+0x3bd/0x9c0
__scsi_remove_device+0x272/0x340
scsi_forget_host+0xf7/0x170
scsi_remove_host+0xd2/0x2a0
sdebug_driver_remove+0x52/0x2f0 [scsi_debug]
device_release_driver_internal+0x368/0x520
bus_remove_device+0x1f1/0x3f0
device_del+0x3bd/0x9c0
device_unregister+0x13/0xa0
sdebug_do_remove_host+0x1fb/0x290 [scsi_debug]
scsi_debug_exit+0x17/0x70 [scsi_debug]
__do_sys_delete_module.isra.0+0x321/0x520
do_syscall_64+0x93/0x180
entry_SYSCALL_64_after_hwframe+0x76/0x7e
other info that might help us debug this:
Chain exists of:
(work_completion)(&(&wb->dwork)->work) --> &fs_info->dev_replace.rwsem --> &q->q_usage_counter(queue)#16
Possible unsafe locking scenario:
CPU0 CPU1
---- ----
lock(&q->q_usage_counter(queue)#16);
lock(&fs_info->dev_replace.rwsem);
lock(&q->q_usage_counter(queue)#16);
lock((work_completion)(&(&wb->dwork)->work));
*** DEADLOCK ***
5 locks held by modprobe/1110:
#0: ffff88811f7bc108 (&dev->mutex){....}-{4:4}, at: device_release_driver_internal+0x8f/0x520
#1: ffff8881022ee0e0 (&shost->scan_mutex){+.+.}-{4:4}, at: scsi_remove_host+0x20/0x2a0
#2: ffff88811b4c4378 (&dev->mutex){....}-{4:4}, at: device_release_driver_internal+0x8f/0x520
#3: ffff8881205b6f20 (&q->q_usage_counter(queue)#16){++++}-{0:0}, at: sd_remove+0x85/0x130
#4: ffffffffa3284360 (rcu_read_lock){....}-{1:3}, at: __flush_work+0xda/0xb60
stack backtrace:
CPU: 0 UID: 0 PID: 1110 Comm: modprobe Not tainted 6.14.0-rc1 #252
Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.16.3-3.fc41 04/01/2014
Call Trace:
<TASK>
dump_stack_lvl+0x6a/0x90
print_circular_bug.cold+0x1e0/0x274
check_noncircular+0x306/0x3f0
? __pfx_check_noncircular+0x10/0x10
? mark_lock+0xf5/0x1650
? __pfx_check_irq_usage+0x10/0x10
? lockdep_lock+0xca/0x1c0
? __pfx_lockdep_lock+0x10/0x10
__lock_acquire+0x2f52/0x5ea0
? __pfx___lock_acquire+0x10/0x10
? __pfx_mark_lock+0x10/0x10
lock_acquire+0x1b1/0x540
? __flush_work+0x38f/0xb60
? __pfx_lock_acquire+0x10/0x10
? __pfx_lock_release+0x10/0x10
? mark_held_locks+0x94/0xe0
? __flush_work+0x38f/0xb60
__flush_work+0x3ac/0xb60
? __flush_work+0x38f/0xb60
? __pfx_mark_lock+0x10/0x10
? __pfx___flush_work+0x10/0x10
? __pfx_wq_barrier_func+0x10/0x10
? __pfx___might_resched+0x10/0x10
? mark_held_locks+0x94/0xe0
wb_shutdown+0x15b/0x1f0
bdi_unregister+0x172/0x5b0
? __pfx_bdi_unregister+0x10/0x10
? up_write+0x1ba/0x510
del_gendisk+0x841/0xa20
? __pfx_del_gendisk+0x10/0x10
? _raw_spin_unlock_irqrestore+0x35/0x60
? __pm_runtime_resume+0x79/0x110
sd_remove+0x85/0x130
device_release_driver_internal+0x368/0x520
? kobject_put+0x5d/0x4a0
bus_remove_device+0x1f1/0x3f0
device_del+0x3bd/0x9c0
? __pfx_device_del+0x10/0x10
__scsi_remove_device+0x272/0x340
scsi_forget_host+0xf7/0x170
scsi_remove_host+0xd2/0x2a0
sdebug_driver_remove+0x52/0x2f0 [scsi_debug]
? kernfs_remove_by_name_ns+0xc0/0xf0
device_release_driver_internal+0x368/0x520
? kobject_put+0x5d/0x4a0
bus_remove_device+0x1f1/0x3f0
device_del+0x3bd/0x9c0
? __pfx_device_del+0x10/0x10
? __pfx___mutex_unlock_slowpath+0x10/0x10
device_unregister+0x13/0xa0
sdebug_do_remove_host+0x1fb/0x290 [scsi_debug]
scsi_debug_exit+0x17/0x70 [scsi_debug]
__do_sys_delete_module.isra.0+0x321/0x520
? __pfx___do_sys_delete_module.isra.0+0x10/0x10
? __pfx_slab_free_after_rcu_debug+0x10/0x10
? kasan_save_stack+0x2c/0x50
? kasan_record_aux_stack+0xa3/0xb0
? __call_rcu_common.constprop.0+0xc4/0xfb0
? kmem_cache_free+0x3a0/0x590
? __x64_sys_close+0x78/0xd0
do_syscall_64+0x93/0x180
? lock_is_held_type+0xd5/0x130
? __call_rcu_common.constprop.0+0x3c0/0xfb0
? lockdep_hardirqs_on+0x78/0x100
? __call_rcu_common.constprop.0+0x3c0/0xfb0
? __pfx___call_rcu_common.constprop.0+0x10/0x10
? kmem_cache_free+0x3a0/0x590
? lockdep_hardirqs_on_prepare+0x16d/0x400
? do_syscall_64+0x9f/0x180
? lockdep_hardirqs_on+0x78/0x100
? do_syscall_64+0x9f/0x180
? __pfx___x64_sys_openat+0x10/0x10
? lockdep_hardirqs_on_prepare+0x16d/0x400
? do_syscall_64+0x9f/0x180
? lockdep_hardirqs_on+0x78/0x100
? do_syscall_64+0x9f/0x180
entry_SYSCALL_64_after_hwframe+0x76/0x7e
RIP: 0033:0x7f436712b68b
Code: 73 01 c3 48 8b 0d 8d a7 0c 00 f7 d8 64 89 01 48 83 c8 ff c3 66 2e 0f 1f 84 00 00 00 00 00 90 f3 0f 1e fa b8 b0 00 00 00 0f 05 <48> 3d 01 f0 ff ff 73 01 c3 48 8b 0d 5d a7 0c 00 f7 d8 64 89 01 48
RSP: 002b:00007ffe9f1a8658 EFLAGS: 00000206 ORIG_RAX: 00000000000000b0
RAX: ffffffffffffffda RBX: 00005559b367fd80 RCX: 00007f436712b68b
RDX: 0000000000000000 RSI: 0000000000000800 RDI: 00005559b367fde8
RBP: 00007ffe9f1a8680 R08: 1999999999999999 R09: 0000000000000000
R10: 00007f43671a5fe0 R11: 0000000000000206 R12: 0000000000000000
R13: 00007ffe9f1a86b0 R14: 0000000000000000 R15: 0000000000000000
</TASK>
Reported-by: Shin'ichiro Kawasaki <shinichiro.kawasaki@wdc.com>
Signed-off-by: Naohiro Aota <naohiro.aota@wdc.com>
Tested-by: Shin'ichiro Kawasaki <shinichiro.kawasaki@wdc.com>
Reviewed-by: Damien Le Moal <dlemoal@kernel.org>
CC: stable@vger.kernel.org # 6.13+
---
fs/btrfs/zoned.c | 18 ++++++++++++++++--
1 file changed, 16 insertions(+), 2 deletions(-)
diff --git a/fs/btrfs/zoned.c b/fs/btrfs/zoned.c
index 4956baf8220a..6c730f6bce10 100644
--- a/fs/btrfs/zoned.c
+++ b/fs/btrfs/zoned.c
@@ -1277,7 +1277,7 @@ struct zone_info {
static int btrfs_load_zone_info(struct btrfs_fs_info *fs_info, int zone_idx,
struct zone_info *info, unsigned long *active,
- struct btrfs_chunk_map *map)
+ struct btrfs_chunk_map *map, bool new)
{
struct btrfs_dev_replace *dev_replace = &fs_info->dev_replace;
struct btrfs_device *device;
@@ -1307,6 +1307,8 @@ static int btrfs_load_zone_info(struct btrfs_fs_info *fs_info, int zone_idx,
return 0;
}
+ ASSERT(!new || btrfs_dev_is_empty_zone(device, info->physical));
+
/* This zone will be used for allocation, so mark this zone non-empty. */
btrfs_dev_clear_zone_empty(device, info->physical);
@@ -1319,6 +1321,18 @@ static int btrfs_load_zone_info(struct btrfs_fs_info *fs_info, int zone_idx,
* to determine the allocation offset within the zone.
*/
WARN_ON(!IS_ALIGNED(info->physical, fs_info->zone_size));
+
+ if (new) {
+ sector_t capacity;
+
+ capacity = bdev_zone_capacity(device->bdev, info->physical >> SECTOR_SHIFT);
+ up_read(&dev_replace->rwsem);
+ info->alloc_offset = 0;
+ info->capacity = capacity << SECTOR_SHIFT;
+
+ return 0;
+ }
+
nofs_flag = memalloc_nofs_save();
ret = btrfs_get_dev_zone(device, info->physical, &zone);
memalloc_nofs_restore(nofs_flag);
@@ -1588,7 +1602,7 @@ int btrfs_load_block_group_zone_info(struct btrfs_block_group *cache, bool new)
}
for (i = 0; i < map->num_stripes; i++) {
- ret = btrfs_load_zone_info(fs_info, i, &zone_info[i], active, map);
+ ret = btrfs_load_zone_info(fs_info, i, &zone_info[i], active, map, new);
if (ret)
goto out;
--
2.49.0
^ permalink raw reply related [flat|nested] 9+ messages in thread