![Jens Axboe](/assets/img/avatar_default.png)
When umount calls sync_filesystem(), we first do a WB_SYNC_NONE writeback to kick off writeback of pending dirty inodes, then follow that up with a WB_SYNC_ALL to wait for it. Since umount already holds the sb s_umount mutex, WB_SYNC_NONE ends up doing nothing and all writeback happens as WB_SYNC_ALL. This can greatly slow down umount, since WB_SYNC_ALL writeback is a data integrity operation and thus a bigger hammer than simple WB_SYNC_NONE. For barrier aware file systems it's a lot slower. Signed-off-by: Jens Axboe <jens.axboe@oracle.com>
353 lines
9.6 KiB
C
353 lines
9.6 KiB
C
/*
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* include/linux/backing-dev.h
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*
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* low-level device information and state which is propagated up through
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* to high-level code.
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*/
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#ifndef _LINUX_BACKING_DEV_H
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#define _LINUX_BACKING_DEV_H
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#include <linux/percpu_counter.h>
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#include <linux/log2.h>
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#include <linux/proportions.h>
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#include <linux/kernel.h>
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#include <linux/fs.h>
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#include <linux/sched.h>
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#include <linux/timer.h>
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#include <linux/writeback.h>
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#include <asm/atomic.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 backing_dev_info.state
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*/
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enum bdi_state {
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BDI_pending, /* On its way to being activated */
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BDI_wb_alloc, /* Default embedded wb allocated */
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BDI_async_congested, /* The async (write) queue is getting full */
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BDI_sync_congested, /* The sync queue is getting full */
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BDI_registered, /* bdi_register() was done */
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BDI_unused, /* Available bits start here */
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};
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typedef int (congested_fn)(void *, int);
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enum bdi_stat_item {
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BDI_RECLAIMABLE,
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BDI_WRITEBACK,
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NR_BDI_STAT_ITEMS
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};
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#define BDI_STAT_BATCH (8*(1+ilog2(nr_cpu_ids)))
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struct bdi_writeback {
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struct list_head list; /* hangs off the bdi */
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struct backing_dev_info *bdi; /* our parent bdi */
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unsigned int nr;
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unsigned long last_old_flush; /* last old data flush */
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struct task_struct *task; /* writeback task */
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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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};
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struct backing_dev_info {
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struct list_head bdi_list;
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struct rcu_head rcu_head;
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unsigned long ra_pages; /* max readahead in PAGE_CACHE_SIZE units */
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unsigned long state; /* Always use atomic bitops on this */
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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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void (*unplug_io_fn)(struct backing_dev_info *, struct page *);
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void *unplug_io_data;
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char *name;
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struct percpu_counter bdi_stat[NR_BDI_STAT_ITEMS];
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struct prop_local_percpu completions;
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int dirty_exceeded;
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unsigned int min_ratio;
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unsigned int max_ratio, max_prop_frac;
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struct bdi_writeback wb; /* default writeback info for this bdi */
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spinlock_t wb_lock; /* protects update side of wb_list */
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struct list_head wb_list; /* the flusher threads hanging off this bdi */
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unsigned long wb_mask; /* bitmask of registered tasks */
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unsigned int wb_cnt; /* number of registered tasks */
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struct list_head work_list;
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struct device *dev;
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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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int bdi_init(struct backing_dev_info *bdi);
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void bdi_destroy(struct backing_dev_info *bdi);
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int bdi_register(struct backing_dev_info *bdi, struct device *parent,
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const char *fmt, ...);
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int bdi_register_dev(struct backing_dev_info *bdi, dev_t dev);
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void bdi_unregister(struct backing_dev_info *bdi);
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int bdi_setup_and_register(struct backing_dev_info *, char *, unsigned int);
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void bdi_start_writeback(struct backing_dev_info *bdi, struct super_block *sb,
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long nr_pages, int sb_locked);
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int bdi_writeback_task(struct bdi_writeback *wb);
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int bdi_has_dirty_io(struct backing_dev_info *bdi);
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extern spinlock_t bdi_lock;
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extern struct list_head bdi_list;
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static inline int wb_has_dirty_io(struct bdi_writeback *wb)
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{
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return !list_empty(&wb->b_dirty) ||
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!list_empty(&wb->b_io) ||
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!list_empty(&wb->b_more_io);
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}
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static inline void __add_bdi_stat(struct backing_dev_info *bdi,
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enum bdi_stat_item item, s64 amount)
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{
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__percpu_counter_add(&bdi->bdi_stat[item], amount, BDI_STAT_BATCH);
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}
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static inline void __inc_bdi_stat(struct backing_dev_info *bdi,
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enum bdi_stat_item item)
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{
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__add_bdi_stat(bdi, item, 1);
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}
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static inline void inc_bdi_stat(struct backing_dev_info *bdi,
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enum bdi_stat_item item)
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{
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unsigned long flags;
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local_irq_save(flags);
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__inc_bdi_stat(bdi, item);
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local_irq_restore(flags);
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}
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static inline void __dec_bdi_stat(struct backing_dev_info *bdi,
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enum bdi_stat_item item)
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{
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__add_bdi_stat(bdi, item, -1);
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}
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static inline void dec_bdi_stat(struct backing_dev_info *bdi,
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enum bdi_stat_item item)
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{
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unsigned long flags;
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local_irq_save(flags);
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__dec_bdi_stat(bdi, item);
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local_irq_restore(flags);
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}
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static inline s64 bdi_stat(struct backing_dev_info *bdi,
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enum bdi_stat_item item)
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{
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return percpu_counter_read_positive(&bdi->bdi_stat[item]);
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}
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static inline s64 __bdi_stat_sum(struct backing_dev_info *bdi,
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enum bdi_stat_item item)
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{
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return percpu_counter_sum_positive(&bdi->bdi_stat[item]);
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}
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static inline s64 bdi_stat_sum(struct backing_dev_info *bdi,
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enum bdi_stat_item item)
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{
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s64 sum;
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unsigned long flags;
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local_irq_save(flags);
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sum = __bdi_stat_sum(bdi, item);
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local_irq_restore(flags);
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return sum;
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}
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extern void bdi_writeout_inc(struct backing_dev_info *bdi);
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/*
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* maximal error of a stat counter.
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*/
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static inline unsigned long bdi_stat_error(struct backing_dev_info *bdi)
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{
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#ifdef CONFIG_SMP
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return nr_cpu_ids * BDI_STAT_BATCH;
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#else
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return 1;
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#endif
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}
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int bdi_set_min_ratio(struct backing_dev_info *bdi, unsigned int min_ratio);
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int bdi_set_max_ratio(struct backing_dev_info *bdi, unsigned int max_ratio);
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/*
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* Flags in backing_dev_info::capability
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*
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* The first three flags control whether dirty pages will contribute to the
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* VM's accounting and whether writepages() should be called for dirty pages
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* (something that would not, for example, be appropriate for ramfs)
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*
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* WARNING: these flags are closely related and should not normally be
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* used separately. The BDI_CAP_NO_ACCT_AND_WRITEBACK combines these
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* three flags into a single convenience macro.
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*
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* BDI_CAP_NO_ACCT_DIRTY: Dirty pages shouldn't contribute to accounting
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* BDI_CAP_NO_WRITEBACK: Don't write pages back
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* BDI_CAP_NO_ACCT_WB: Don't automatically account writeback pages
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*
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* These flags let !MMU mmap() govern direct device mapping vs immediate
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* copying more easily for MAP_PRIVATE, especially for ROM filesystems.
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*
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* BDI_CAP_MAP_COPY: Copy can be mapped (MAP_PRIVATE)
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* BDI_CAP_MAP_DIRECT: Can be mapped directly (MAP_SHARED)
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* BDI_CAP_READ_MAP: Can be mapped for reading
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* BDI_CAP_WRITE_MAP: Can be mapped for writing
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* BDI_CAP_EXEC_MAP: Can be mapped for execution
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*
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* BDI_CAP_SWAP_BACKED: Count shmem/tmpfs objects as swap-backed.
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*/
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#define BDI_CAP_NO_ACCT_DIRTY 0x00000001
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#define BDI_CAP_NO_WRITEBACK 0x00000002
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#define BDI_CAP_MAP_COPY 0x00000004
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#define BDI_CAP_MAP_DIRECT 0x00000008
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#define BDI_CAP_READ_MAP 0x00000010
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#define BDI_CAP_WRITE_MAP 0x00000020
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#define BDI_CAP_EXEC_MAP 0x00000040
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#define BDI_CAP_NO_ACCT_WB 0x00000080
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#define BDI_CAP_SWAP_BACKED 0x00000100
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#define BDI_CAP_VMFLAGS \
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(BDI_CAP_READ_MAP | BDI_CAP_WRITE_MAP | BDI_CAP_EXEC_MAP)
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#define BDI_CAP_NO_ACCT_AND_WRITEBACK \
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(BDI_CAP_NO_WRITEBACK | BDI_CAP_NO_ACCT_DIRTY | BDI_CAP_NO_ACCT_WB)
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#if defined(VM_MAYREAD) && \
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(BDI_CAP_READ_MAP != VM_MAYREAD || \
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BDI_CAP_WRITE_MAP != VM_MAYWRITE || \
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BDI_CAP_EXEC_MAP != VM_MAYEXEC)
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#error please change backing_dev_info::capabilities flags
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#endif
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extern struct backing_dev_info default_backing_dev_info;
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extern struct backing_dev_info noop_backing_dev_info;
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void default_unplug_io_fn(struct backing_dev_info *bdi, struct page *page);
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int writeback_in_progress(struct backing_dev_info *bdi);
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static inline int bdi_congested(struct backing_dev_info *bdi, int bdi_bits)
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{
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if (bdi->congested_fn)
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return bdi->congested_fn(bdi->congested_data, bdi_bits);
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return (bdi->state & bdi_bits);
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}
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static inline int bdi_read_congested(struct backing_dev_info *bdi)
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{
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return bdi_congested(bdi, 1 << BDI_sync_congested);
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}
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static inline int bdi_write_congested(struct backing_dev_info *bdi)
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{
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return bdi_congested(bdi, 1 << BDI_async_congested);
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}
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static inline int bdi_rw_congested(struct backing_dev_info *bdi)
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{
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return bdi_congested(bdi, (1 << BDI_sync_congested) |
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(1 << BDI_async_congested));
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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_bdi_congested(struct backing_dev_info *bdi, int sync);
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void set_bdi_congested(struct backing_dev_info *bdi, int sync);
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long congestion_wait(int sync, long timeout);
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static inline bool bdi_cap_writeback_dirty(struct backing_dev_info *bdi)
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{
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return !(bdi->capabilities & BDI_CAP_NO_WRITEBACK);
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}
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static inline bool bdi_cap_account_dirty(struct backing_dev_info *bdi)
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{
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return !(bdi->capabilities & BDI_CAP_NO_ACCT_DIRTY);
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}
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static inline bool bdi_cap_account_writeback(struct backing_dev_info *bdi)
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{
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/* Paranoia: BDI_CAP_NO_WRITEBACK implies BDI_CAP_NO_ACCT_WB */
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return !(bdi->capabilities & (BDI_CAP_NO_ACCT_WB |
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BDI_CAP_NO_WRITEBACK));
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}
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static inline bool bdi_cap_swap_backed(struct backing_dev_info *bdi)
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{
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return bdi->capabilities & BDI_CAP_SWAP_BACKED;
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}
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static inline bool bdi_cap_flush_forker(struct backing_dev_info *bdi)
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{
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return bdi == &default_backing_dev_info;
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}
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static inline bool mapping_cap_writeback_dirty(struct address_space *mapping)
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{
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return bdi_cap_writeback_dirty(mapping->backing_dev_info);
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}
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static inline bool mapping_cap_account_dirty(struct address_space *mapping)
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{
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return bdi_cap_account_dirty(mapping->backing_dev_info);
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}
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static inline bool mapping_cap_swap_backed(struct address_space *mapping)
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{
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return bdi_cap_swap_backed(mapping->backing_dev_info);
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}
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static inline int bdi_sched_wait(void *word)
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{
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schedule();
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return 0;
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}
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static inline void blk_run_backing_dev(struct backing_dev_info *bdi,
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struct page *page)
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{
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if (bdi && bdi->unplug_io_fn)
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bdi->unplug_io_fn(bdi, page);
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}
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static inline void blk_run_address_space(struct address_space *mapping)
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{
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if (mapping)
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blk_run_backing_dev(mapping->backing_dev_info, NULL);
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}
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#endif /* _LINUX_BACKING_DEV_H */
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