![Christoph Hellwig](/assets/img/avatar_default.png)
First remove items from work_list as soon as we start working on them. This means we don't have to track any pending or visited state and can get rid of all the RCU magic freeing the work items - we can simply free them once the operation has finished. Second use a real completion for tracking synchronous requests - if the caller sets the completion pointer we complete it, otherwise use it as a boolean indicator that we can free the work item directly. Third unify struct wb_writeback_args and struct bdi_work into a single data structure, wb_writeback_work. Previous we set all parameters into a struct wb_writeback_args, copied it into struct bdi_work, copied it again on the stack to use it there. Instead of just allocate one structure dynamically or on the stack and use it all the way through the stack. Signed-off-by: Christoph Hellwig <hch@lst.de> Signed-off-by: Jens Axboe <jaxboe@fusionio.com>
352 lines
9.5 KiB
C
352 lines
9.5 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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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, long nr_pages);
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void bdi_start_background_writeback(struct backing_dev_info *bdi);
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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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void bdi_arm_supers_timer(void);
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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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