![Dan Williams](/assets/img/avatar_default.png)
The name for a bdi of a gendisk is derived from the gendisk's devt. However, since the gendisk is destroyed before the bdi it leaves a window where a new gendisk could dynamically reuse the same devt while a bdi with the same name is still live. Arrange for the bdi to hold a reference against its "owner" disk device while it is registered. Otherwise we can hit sysfs duplicate name collisions like the following: WARNING: CPU: 10 PID: 2078 at fs/sysfs/dir.c:31 sysfs_warn_dup+0x64/0x80 sysfs: cannot create duplicate filename '/devices/virtual/bdi/259:1' Hardware name: HP ProLiant DL580 Gen8, BIOS P79 05/06/2015 0000000000000286 0000000002c04ad5 ffff88006f24f970 ffffffff8134caec ffff88006f24f9c0 0000000000000000 ffff88006f24f9b0 ffffffff8108c351 0000001f0000000c ffff88105d236000 ffff88105d1031e0 ffff8800357427f8 Call Trace: [<ffffffff8134caec>] dump_stack+0x63/0x87 [<ffffffff8108c351>] __warn+0xd1/0xf0 [<ffffffff8108c3cf>] warn_slowpath_fmt+0x5f/0x80 [<ffffffff812a0d34>] sysfs_warn_dup+0x64/0x80 [<ffffffff812a0e1e>] sysfs_create_dir_ns+0x7e/0x90 [<ffffffff8134faaa>] kobject_add_internal+0xaa/0x320 [<ffffffff81358d4e>] ? vsnprintf+0x34e/0x4d0 [<ffffffff8134ff55>] kobject_add+0x75/0xd0 [<ffffffff816e66b2>] ? mutex_lock+0x12/0x2f [<ffffffff8148b0a5>] device_add+0x125/0x610 [<ffffffff8148b788>] device_create_groups_vargs+0xd8/0x100 [<ffffffff8148b7cc>] device_create_vargs+0x1c/0x20 [<ffffffff811b775c>] bdi_register+0x8c/0x180 [<ffffffff811b7877>] bdi_register_dev+0x27/0x30 [<ffffffff813317f5>] add_disk+0x175/0x4a0 Cc: <stable@vger.kernel.org> Reported-by: Yi Zhang <yizhan@redhat.com> Tested-by: Yi Zhang <yizhan@redhat.com> Signed-off-by: Dan Williams <dan.j.williams@intel.com> Fixed up missing 0 return in bdi_register_owner(). Signed-off-by: Jens Axboe <axboe@fb.com>
261 lines
7.4 KiB
C
261 lines
7.4 KiB
C
#ifndef __LINUX_BACKING_DEV_DEFS_H
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#define __LINUX_BACKING_DEV_DEFS_H
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#include <linux/list.h>
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#include <linux/radix-tree.h>
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#include <linux/rbtree.h>
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#include <linux/spinlock.h>
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#include <linux/percpu_counter.h>
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#include <linux/percpu-refcount.h>
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#include <linux/flex_proportions.h>
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#include <linux/timer.h>
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#include <linux/workqueue.h>
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struct page;
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struct device;
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struct dentry;
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/*
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* Bits in bdi_writeback.state
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*/
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enum wb_state {
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WB_registered, /* bdi_register() was done */
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WB_writeback_running, /* Writeback is in progress */
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WB_has_dirty_io, /* Dirty inodes on ->b_{dirty|io|more_io} */
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};
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enum wb_congested_state {
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WB_async_congested, /* The async (write) queue is getting full */
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WB_sync_congested, /* The sync queue is getting full */
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};
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typedef int (congested_fn)(void *, int);
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enum wb_stat_item {
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WB_RECLAIMABLE,
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WB_WRITEBACK,
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WB_DIRTIED,
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WB_WRITTEN,
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NR_WB_STAT_ITEMS
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};
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#define WB_STAT_BATCH (8*(1+ilog2(nr_cpu_ids)))
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/*
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* For cgroup writeback, multiple wb's may map to the same blkcg. Those
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* wb's can operate mostly independently but should share the congested
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* state. To facilitate such sharing, the congested state is tracked using
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* the following struct which is created on demand, indexed by blkcg ID on
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* its bdi, and refcounted.
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*/
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struct bdi_writeback_congested {
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unsigned long state; /* WB_[a]sync_congested flags */
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atomic_t refcnt; /* nr of attached wb's and blkg */
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#ifdef CONFIG_CGROUP_WRITEBACK
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struct backing_dev_info *bdi; /* the associated bdi */
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int blkcg_id; /* ID of the associated blkcg */
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struct rb_node rb_node; /* on bdi->cgwb_congestion_tree */
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#endif
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};
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/*
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* Each wb (bdi_writeback) can perform writeback operations, is measured
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* and throttled, independently. Without cgroup writeback, each bdi
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* (bdi_writeback) is served by its embedded bdi->wb.
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*
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* On the default hierarchy, blkcg implicitly enables memcg. This allows
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* using memcg's page ownership for attributing writeback IOs, and every
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* memcg - blkcg combination can be served by its own wb by assigning a
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* dedicated wb to each memcg, which enables isolation across different
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* cgroups and propagation of IO back pressure down from the IO layer upto
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* the tasks which are generating the dirty pages to be written back.
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*
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* A cgroup wb is indexed on its bdi by the ID of the associated memcg,
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* refcounted with the number of inodes attached to it, and pins the memcg
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* and the corresponding blkcg. As the corresponding blkcg for a memcg may
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* change as blkcg is disabled and enabled higher up in the hierarchy, a wb
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* is tested for blkcg after lookup and removed from index on mismatch so
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* that a new wb for the combination can be created.
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*/
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struct bdi_writeback {
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struct backing_dev_info *bdi; /* our parent bdi */
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unsigned long state; /* Always use atomic bitops on this */
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unsigned long last_old_flush; /* last old data flush */
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struct list_head b_dirty; /* dirty inodes */
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struct list_head b_io; /* parked for writeback */
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struct list_head b_more_io; /* parked for more writeback */
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struct list_head b_dirty_time; /* time stamps are dirty */
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spinlock_t list_lock; /* protects the b_* lists */
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struct percpu_counter stat[NR_WB_STAT_ITEMS];
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struct bdi_writeback_congested *congested;
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unsigned long bw_time_stamp; /* last time write bw is updated */
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unsigned long dirtied_stamp;
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unsigned long written_stamp; /* pages written at bw_time_stamp */
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unsigned long write_bandwidth; /* the estimated write bandwidth */
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unsigned long avg_write_bandwidth; /* further smoothed write bw, > 0 */
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/*
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* The base dirty throttle rate, re-calculated on every 200ms.
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* All the bdi tasks' dirty rate will be curbed under it.
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* @dirty_ratelimit tracks the estimated @balanced_dirty_ratelimit
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* in small steps and is much more smooth/stable than the latter.
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*/
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unsigned long dirty_ratelimit;
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unsigned long balanced_dirty_ratelimit;
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struct fprop_local_percpu completions;
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int dirty_exceeded;
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spinlock_t work_lock; /* protects work_list & dwork scheduling */
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struct list_head work_list;
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struct delayed_work dwork; /* work item used for writeback */
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struct list_head bdi_node; /* anchored at bdi->wb_list */
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#ifdef CONFIG_CGROUP_WRITEBACK
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struct percpu_ref refcnt; /* used only for !root wb's */
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struct fprop_local_percpu memcg_completions;
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struct cgroup_subsys_state *memcg_css; /* the associated memcg */
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struct cgroup_subsys_state *blkcg_css; /* and blkcg */
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struct list_head memcg_node; /* anchored at memcg->cgwb_list */
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struct list_head blkcg_node; /* anchored at blkcg->cgwb_list */
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union {
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struct work_struct release_work;
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struct rcu_head rcu;
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};
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#endif
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};
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struct backing_dev_info {
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struct list_head bdi_list;
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unsigned long ra_pages; /* max readahead in PAGE_SIZE units */
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unsigned int capabilities; /* Device capabilities */
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congested_fn *congested_fn; /* Function pointer if device is md/dm */
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void *congested_data; /* Pointer to aux data for congested func */
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char *name;
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unsigned int min_ratio;
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unsigned int max_ratio, max_prop_frac;
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/*
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* Sum of avg_write_bw of wbs with dirty inodes. > 0 if there are
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* any dirty wbs, which is depended upon by bdi_has_dirty().
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*/
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atomic_long_t tot_write_bandwidth;
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struct bdi_writeback wb; /* the root writeback info for this bdi */
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struct list_head wb_list; /* list of all wbs */
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#ifdef CONFIG_CGROUP_WRITEBACK
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struct radix_tree_root cgwb_tree; /* radix tree of active cgroup wbs */
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struct rb_root cgwb_congested_tree; /* their congested states */
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atomic_t usage_cnt; /* counts both cgwbs and cgwb_contested's */
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#else
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struct bdi_writeback_congested *wb_congested;
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#endif
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wait_queue_head_t wb_waitq;
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struct device *dev;
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struct device *owner;
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struct timer_list laptop_mode_wb_timer;
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#ifdef CONFIG_DEBUG_FS
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struct dentry *debug_dir;
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struct dentry *debug_stats;
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#endif
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};
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enum {
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BLK_RW_ASYNC = 0,
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BLK_RW_SYNC = 1,
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};
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void clear_wb_congested(struct bdi_writeback_congested *congested, int sync);
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void set_wb_congested(struct bdi_writeback_congested *congested, int sync);
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static inline void clear_bdi_congested(struct backing_dev_info *bdi, int sync)
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{
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clear_wb_congested(bdi->wb.congested, sync);
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}
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static inline void set_bdi_congested(struct backing_dev_info *bdi, int sync)
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{
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set_wb_congested(bdi->wb.congested, sync);
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}
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#ifdef CONFIG_CGROUP_WRITEBACK
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/**
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* wb_tryget - try to increment a wb's refcount
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* @wb: bdi_writeback to get
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*/
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static inline bool wb_tryget(struct bdi_writeback *wb)
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{
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if (wb != &wb->bdi->wb)
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return percpu_ref_tryget(&wb->refcnt);
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return true;
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}
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/**
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* wb_get - increment a wb's refcount
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* @wb: bdi_writeback to get
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*/
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static inline void wb_get(struct bdi_writeback *wb)
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{
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if (wb != &wb->bdi->wb)
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percpu_ref_get(&wb->refcnt);
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}
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/**
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* wb_put - decrement a wb's refcount
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* @wb: bdi_writeback to put
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*/
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static inline void wb_put(struct bdi_writeback *wb)
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{
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if (wb != &wb->bdi->wb)
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percpu_ref_put(&wb->refcnt);
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}
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/**
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* wb_dying - is a wb dying?
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* @wb: bdi_writeback of interest
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*
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* Returns whether @wb is unlinked and being drained.
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*/
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static inline bool wb_dying(struct bdi_writeback *wb)
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{
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return percpu_ref_is_dying(&wb->refcnt);
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}
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#else /* CONFIG_CGROUP_WRITEBACK */
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static inline bool wb_tryget(struct bdi_writeback *wb)
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{
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return true;
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}
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static inline void wb_get(struct bdi_writeback *wb)
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{
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}
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static inline void wb_put(struct bdi_writeback *wb)
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{
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}
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static inline bool wb_dying(struct bdi_writeback *wb)
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{
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return false;
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}
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#endif /* CONFIG_CGROUP_WRITEBACK */
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#endif /* __LINUX_BACKING_DEV_DEFS_H */
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