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![Sebastian Andrzej Siewior](/assets/img/avatar_default.png)
refcount_t type and corresponding API should be used instead of atomic_t when the variable is used as a reference counter. This permits avoiding accidental refcounter overflows that might lead to use-after-free situations. Link: http://lkml.kernel.org/r/20180703200141.28415-4-bigeasy@linutronix.de Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de> Reviewed-by: Andrew Morton <akpm@linux-foundation.org> Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org> Suggested-by: Peter Zijlstra <peterz@infradead.org> Cc: Jens Axboe <axboe@kernel.dk> Cc: Ingo Molnar <mingo@elte.hu> Cc: Thomas Gleixner <tglx@linutronix.de> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
501 lines
14 KiB
C
501 lines
14 KiB
C
/* SPDX-License-Identifier: GPL-2.0 */
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/*
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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/kernel.h>
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#include <linux/fs.h>
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#include <linux/sched.h>
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#include <linux/blkdev.h>
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#include <linux/writeback.h>
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#include <linux/blk-cgroup.h>
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#include <linux/backing-dev-defs.h>
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#include <linux/slab.h>
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static inline struct backing_dev_info *bdi_get(struct backing_dev_info *bdi)
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{
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kref_get(&bdi->refcnt);
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return bdi;
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}
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void bdi_put(struct backing_dev_info *bdi);
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__printf(2, 3)
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int bdi_register(struct backing_dev_info *bdi, const char *fmt, ...);
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__printf(2, 0)
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int bdi_register_va(struct backing_dev_info *bdi, const char *fmt,
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va_list args);
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int bdi_register_owner(struct backing_dev_info *bdi, struct device *owner);
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void bdi_unregister(struct backing_dev_info *bdi);
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struct backing_dev_info *bdi_alloc_node(gfp_t gfp_mask, int node_id);
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static inline struct backing_dev_info *bdi_alloc(gfp_t gfp_mask)
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{
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return bdi_alloc_node(gfp_mask, NUMA_NO_NODE);
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}
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void wb_start_background_writeback(struct bdi_writeback *wb);
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void wb_workfn(struct work_struct *work);
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void wb_wakeup_delayed(struct bdi_writeback *wb);
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extern spinlock_t bdi_lock;
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extern struct list_head bdi_list;
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extern struct workqueue_struct *bdi_wq;
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static inline bool wb_has_dirty_io(struct bdi_writeback *wb)
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{
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return test_bit(WB_has_dirty_io, &wb->state);
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}
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static inline bool bdi_has_dirty_io(struct backing_dev_info *bdi)
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{
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/*
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* @bdi->tot_write_bandwidth is guaranteed to be > 0 if there are
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* any dirty wbs. See wb_update_write_bandwidth().
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*/
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return atomic_long_read(&bdi->tot_write_bandwidth);
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}
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static inline void __add_wb_stat(struct bdi_writeback *wb,
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enum wb_stat_item item, s64 amount)
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{
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percpu_counter_add_batch(&wb->stat[item], amount, WB_STAT_BATCH);
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}
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static inline void inc_wb_stat(struct bdi_writeback *wb, enum wb_stat_item item)
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{
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__add_wb_stat(wb, item, 1);
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}
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static inline void dec_wb_stat(struct bdi_writeback *wb, enum wb_stat_item item)
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{
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__add_wb_stat(wb, item, -1);
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}
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static inline s64 wb_stat(struct bdi_writeback *wb, enum wb_stat_item item)
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{
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return percpu_counter_read_positive(&wb->stat[item]);
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}
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static inline s64 wb_stat_sum(struct bdi_writeback *wb, enum wb_stat_item item)
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{
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return percpu_counter_sum_positive(&wb->stat[item]);
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}
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extern void wb_writeout_inc(struct bdi_writeback *wb);
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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 wb_stat_error(void)
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{
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#ifdef CONFIG_SMP
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return nr_cpu_ids * WB_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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* BDI_CAP_STRICTLIMIT: Keep number of dirty pages below bdi threshold.
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*
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* BDI_CAP_CGROUP_WRITEBACK: Supports cgroup-aware writeback.
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* BDI_CAP_SYNCHRONOUS_IO: Device is so fast that asynchronous IO would be
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* inefficient.
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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_NO_ACCT_WB 0x00000004
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#define BDI_CAP_STABLE_WRITES 0x00000008
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#define BDI_CAP_STRICTLIMIT 0x00000010
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#define BDI_CAP_CGROUP_WRITEBACK 0x00000020
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#define BDI_CAP_SYNCHRONOUS_IO 0x00000040
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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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extern struct backing_dev_info noop_backing_dev_info;
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/**
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* writeback_in_progress - determine whether there is writeback in progress
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* @wb: bdi_writeback of interest
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*
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* Determine whether there is writeback waiting to be handled against a
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* bdi_writeback.
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*/
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static inline bool writeback_in_progress(struct bdi_writeback *wb)
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{
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return test_bit(WB_writeback_running, &wb->state);
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}
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static inline struct backing_dev_info *inode_to_bdi(struct inode *inode)
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{
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struct super_block *sb;
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if (!inode)
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return &noop_backing_dev_info;
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sb = inode->i_sb;
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#ifdef CONFIG_BLOCK
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if (sb_is_blkdev_sb(sb))
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return I_BDEV(inode)->bd_bdi;
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#endif
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return sb->s_bdi;
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}
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static inline int wb_congested(struct bdi_writeback *wb, int cong_bits)
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{
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struct backing_dev_info *bdi = wb->bdi;
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if (bdi->congested_fn)
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return bdi->congested_fn(bdi->congested_data, cong_bits);
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return wb->congested->state & cong_bits;
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}
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long congestion_wait(int sync, long timeout);
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long wait_iff_congested(int sync, long timeout);
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static inline bool bdi_cap_synchronous_io(struct backing_dev_info *bdi)
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{
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return bdi->capabilities & BDI_CAP_SYNCHRONOUS_IO;
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}
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static inline bool bdi_cap_stable_pages_required(struct backing_dev_info *bdi)
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{
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return bdi->capabilities & BDI_CAP_STABLE_WRITES;
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}
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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 mapping_cap_writeback_dirty(struct address_space *mapping)
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{
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return bdi_cap_writeback_dirty(inode_to_bdi(mapping->host));
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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(inode_to_bdi(mapping->host));
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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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#ifdef CONFIG_CGROUP_WRITEBACK
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struct bdi_writeback_congested *
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wb_congested_get_create(struct backing_dev_info *bdi, int blkcg_id, gfp_t gfp);
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void wb_congested_put(struct bdi_writeback_congested *congested);
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struct bdi_writeback *wb_get_create(struct backing_dev_info *bdi,
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struct cgroup_subsys_state *memcg_css,
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gfp_t gfp);
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void wb_memcg_offline(struct mem_cgroup *memcg);
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void wb_blkcg_offline(struct blkcg *blkcg);
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int inode_congested(struct inode *inode, int cong_bits);
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/**
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* inode_cgwb_enabled - test whether cgroup writeback is enabled on an inode
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* @inode: inode of interest
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*
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* cgroup writeback requires support from both the bdi and filesystem.
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* Also, both memcg and iocg have to be on the default hierarchy. Test
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* whether all conditions are met.
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*
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* Note that the test result may change dynamically on the same inode
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* depending on how memcg and iocg are configured.
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*/
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static inline bool inode_cgwb_enabled(struct inode *inode)
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{
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struct backing_dev_info *bdi = inode_to_bdi(inode);
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return cgroup_subsys_on_dfl(memory_cgrp_subsys) &&
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cgroup_subsys_on_dfl(io_cgrp_subsys) &&
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bdi_cap_account_dirty(bdi) &&
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(bdi->capabilities & BDI_CAP_CGROUP_WRITEBACK) &&
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(inode->i_sb->s_iflags & SB_I_CGROUPWB);
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}
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/**
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* wb_find_current - find wb for %current on a bdi
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* @bdi: bdi of interest
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*
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* Find the wb of @bdi which matches both the memcg and blkcg of %current.
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* Must be called under rcu_read_lock() which protects the returend wb.
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* NULL if not found.
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*/
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static inline struct bdi_writeback *wb_find_current(struct backing_dev_info *bdi)
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{
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struct cgroup_subsys_state *memcg_css;
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struct bdi_writeback *wb;
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memcg_css = task_css(current, memory_cgrp_id);
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if (!memcg_css->parent)
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return &bdi->wb;
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wb = radix_tree_lookup(&bdi->cgwb_tree, memcg_css->id);
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/*
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* %current's blkcg equals the effective blkcg of its memcg. No
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* need to use the relatively expensive cgroup_get_e_css().
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*/
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if (likely(wb && wb->blkcg_css == task_css(current, io_cgrp_id)))
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return wb;
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return NULL;
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}
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/**
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* wb_get_create_current - get or create wb for %current on a bdi
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* @bdi: bdi of interest
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* @gfp: allocation mask
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*
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* Equivalent to wb_get_create() on %current's memcg. This function is
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* called from a relatively hot path and optimizes the common cases using
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* wb_find_current().
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*/
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static inline struct bdi_writeback *
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wb_get_create_current(struct backing_dev_info *bdi, gfp_t gfp)
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{
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struct bdi_writeback *wb;
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rcu_read_lock();
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wb = wb_find_current(bdi);
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if (wb && unlikely(!wb_tryget(wb)))
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wb = NULL;
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rcu_read_unlock();
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if (unlikely(!wb)) {
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struct cgroup_subsys_state *memcg_css;
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memcg_css = task_get_css(current, memory_cgrp_id);
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wb = wb_get_create(bdi, memcg_css, gfp);
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css_put(memcg_css);
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}
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return wb;
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}
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/**
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* inode_to_wb_is_valid - test whether an inode has a wb associated
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* @inode: inode of interest
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*
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* Returns %true if @inode has a wb associated. May be called without any
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* locking.
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*/
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static inline bool inode_to_wb_is_valid(struct inode *inode)
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{
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return inode->i_wb;
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}
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/**
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* inode_to_wb - determine the wb of an inode
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* @inode: inode of interest
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*
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* Returns the wb @inode is currently associated with. The caller must be
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* holding either @inode->i_lock, the i_pages lock, or the
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* associated wb's list_lock.
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*/
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static inline struct bdi_writeback *inode_to_wb(const struct inode *inode)
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{
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#ifdef CONFIG_LOCKDEP
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WARN_ON_ONCE(debug_locks &&
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(!lockdep_is_held(&inode->i_lock) &&
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!lockdep_is_held(&inode->i_mapping->i_pages.xa_lock) &&
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!lockdep_is_held(&inode->i_wb->list_lock)));
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#endif
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return inode->i_wb;
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}
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/**
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* unlocked_inode_to_wb_begin - begin unlocked inode wb access transaction
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* @inode: target inode
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* @cookie: output param, to be passed to the end function
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*
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* The caller wants to access the wb associated with @inode but isn't
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* holding inode->i_lock, the i_pages lock or wb->list_lock. This
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* function determines the wb associated with @inode and ensures that the
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* association doesn't change until the transaction is finished with
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* unlocked_inode_to_wb_end().
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*
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* The caller must call unlocked_inode_to_wb_end() with *@cookie afterwards and
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* can't sleep during the transaction. IRQs may or may not be disabled on
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* return.
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*/
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static inline struct bdi_writeback *
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unlocked_inode_to_wb_begin(struct inode *inode, struct wb_lock_cookie *cookie)
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{
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rcu_read_lock();
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/*
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* Paired with store_release in inode_switch_wb_work_fn() and
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* ensures that we see the new wb if we see cleared I_WB_SWITCH.
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*/
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cookie->locked = smp_load_acquire(&inode->i_state) & I_WB_SWITCH;
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if (unlikely(cookie->locked))
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xa_lock_irqsave(&inode->i_mapping->i_pages, cookie->flags);
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/*
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* Protected by either !I_WB_SWITCH + rcu_read_lock() or the i_pages
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* lock. inode_to_wb() will bark. Deref directly.
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*/
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return inode->i_wb;
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}
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/**
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* unlocked_inode_to_wb_end - end inode wb access transaction
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* @inode: target inode
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* @cookie: @cookie from unlocked_inode_to_wb_begin()
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*/
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static inline void unlocked_inode_to_wb_end(struct inode *inode,
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struct wb_lock_cookie *cookie)
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{
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if (unlikely(cookie->locked))
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xa_unlock_irqrestore(&inode->i_mapping->i_pages, cookie->flags);
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rcu_read_unlock();
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}
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#else /* CONFIG_CGROUP_WRITEBACK */
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static inline bool inode_cgwb_enabled(struct inode *inode)
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{
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return false;
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}
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static inline struct bdi_writeback_congested *
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wb_congested_get_create(struct backing_dev_info *bdi, int blkcg_id, gfp_t gfp)
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{
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refcount_inc(&bdi->wb_congested->refcnt);
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return bdi->wb_congested;
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}
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static inline void wb_congested_put(struct bdi_writeback_congested *congested)
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{
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if (refcount_dec_and_test(&congested->refcnt))
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kfree(congested);
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}
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static inline struct bdi_writeback *wb_find_current(struct backing_dev_info *bdi)
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{
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return &bdi->wb;
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}
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static inline struct bdi_writeback *
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wb_get_create_current(struct backing_dev_info *bdi, gfp_t gfp)
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{
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return &bdi->wb;
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}
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static inline bool inode_to_wb_is_valid(struct inode *inode)
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{
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return true;
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}
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static inline struct bdi_writeback *inode_to_wb(struct inode *inode)
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{
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return &inode_to_bdi(inode)->wb;
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}
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static inline struct bdi_writeback *
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unlocked_inode_to_wb_begin(struct inode *inode, struct wb_lock_cookie *cookie)
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{
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return inode_to_wb(inode);
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}
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static inline void unlocked_inode_to_wb_end(struct inode *inode,
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struct wb_lock_cookie *cookie)
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{
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}
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static inline void wb_memcg_offline(struct mem_cgroup *memcg)
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{
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}
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static inline void wb_blkcg_offline(struct blkcg *blkcg)
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{
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}
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static inline int inode_congested(struct inode *inode, int cong_bits)
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{
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return wb_congested(&inode_to_bdi(inode)->wb, cong_bits);
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}
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#endif /* CONFIG_CGROUP_WRITEBACK */
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static inline int inode_read_congested(struct inode *inode)
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{
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return inode_congested(inode, 1 << WB_sync_congested);
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}
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static inline int inode_write_congested(struct inode *inode)
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{
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return inode_congested(inode, 1 << WB_async_congested);
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}
|
|
|
|
static inline int inode_rw_congested(struct inode *inode)
|
|
{
|
|
return inode_congested(inode, (1 << WB_sync_congested) |
|
|
(1 << WB_async_congested));
|
|
}
|
|
|
|
static inline int bdi_congested(struct backing_dev_info *bdi, int cong_bits)
|
|
{
|
|
return wb_congested(&bdi->wb, cong_bits);
|
|
}
|
|
|
|
static inline int bdi_read_congested(struct backing_dev_info *bdi)
|
|
{
|
|
return bdi_congested(bdi, 1 << WB_sync_congested);
|
|
}
|
|
|
|
static inline int bdi_write_congested(struct backing_dev_info *bdi)
|
|
{
|
|
return bdi_congested(bdi, 1 << WB_async_congested);
|
|
}
|
|
|
|
static inline int bdi_rw_congested(struct backing_dev_info *bdi)
|
|
{
|
|
return bdi_congested(bdi, (1 << WB_sync_congested) |
|
|
(1 << WB_async_congested));
|
|
}
|
|
|
|
#endif /* _LINUX_BACKING_DEV_H */
|