diff options
Diffstat (limited to '')
| -rw-r--r-- | mm/page-writeback.c | 1036 |
1 files changed, 640 insertions, 396 deletions
diff --git a/mm/page-writeback.c b/mm/page-writeback.c index 2caf780a42e7..7e9d8d857ecc 100644 --- a/mm/page-writeback.c +++ b/mm/page-writeback.c @@ -32,7 +32,6 @@ #include <linux/sysctl.h> #include <linux/cpu.h> #include <linux/syscalls.h> -#include <linux/buffer_head.h> /* __set_page_dirty_buffers */ #include <linux/pagevec.h> #include <linux/timer.h> #include <linux/sched/rt.h> @@ -71,30 +70,30 @@ static long ratelimit_pages = 32; /* * Start background writeback (via writeback threads) at this percentage */ -int dirty_background_ratio = 10; +static int dirty_background_ratio = 10; /* * dirty_background_bytes starts at 0 (disabled) so that it is a function of * dirty_background_ratio * the amount of dirtyable memory */ -unsigned long dirty_background_bytes; +static unsigned long dirty_background_bytes; /* * free highmem will not be subtracted from the total free memory * for calculating free ratios if vm_highmem_is_dirtyable is true */ -int vm_highmem_is_dirtyable; +static int vm_highmem_is_dirtyable; /* * The generator of dirty data starts writeback at this percentage */ -int vm_dirty_ratio = 20; +static int vm_dirty_ratio = 20; /* * vm_dirty_bytes starts at 0 (disabled) so that it is a function of * vm_dirty_ratio * the amount of dirtyable memory */ -unsigned long vm_dirty_bytes; +static unsigned long vm_dirty_bytes; /* * The interval between `kupdate'-style writebacks @@ -109,11 +108,6 @@ EXPORT_SYMBOL_GPL(dirty_writeback_interval); unsigned int dirty_expire_interval = 30 * 100; /* centiseconds */ /* - * Flag that makes the machine dump writes/reads and block dirtyings. - */ -int block_dump; - -/* * Flag that puts the machine in "laptop mode". Doubles as a timeout in jiffies: * a full sync is triggered after this time elapses without any disk activity. */ @@ -189,7 +183,7 @@ static struct fprop_local_percpu *wb_memcg_completions(struct bdi_writeback *wb) static void wb_min_max_ratio(struct bdi_writeback *wb, unsigned long *minp, unsigned long *maxp) { - unsigned long this_bw = wb->avg_write_bandwidth; + unsigned long this_bw = READ_ONCE(wb->avg_write_bandwidth); unsigned long tot_bw = atomic_long_read(&wb->bdi->tot_write_bandwidth); unsigned long long min = wb->bdi->min_ratio; unsigned long long max = wb->bdi->max_ratio; @@ -257,7 +251,7 @@ static void wb_min_max_ratio(struct bdi_writeback *wb, * requiring writeback. * * This number of dirtyable pages is the base value of which the - * user-configurable dirty ratio is the effictive number of pages that + * user-configurable dirty ratio is the effective number of pages that * are allowed to be actually dirtied. Per individual zone, or * globally by using the sum of dirtyable pages over all zones. * @@ -330,18 +324,6 @@ static unsigned long highmem_dirtyable_memory(unsigned long total) } /* - * Unreclaimable memory (kernel memory or anonymous memory - * without swap) can bring down the dirtyable pages below - * the zone's dirty balance reserve and the above calculation - * will underflow. However we still want to add in nodes - * which are below threshold (negative values) to get a more - * accurate calculation but make sure that the total never - * underflows. - */ - if ((long)x < 0) - x = 0; - - /* * Make sure that the number of highmem pages is never larger * than the number of the total dirtyable memory. This can only * occur in very strange VM situations but we want to make sure @@ -387,8 +369,7 @@ static unsigned long global_dirtyable_memory(void) * Calculate @dtc->thresh and ->bg_thresh considering * vm_dirty_{bytes|ratio} and dirty_background_{bytes|ratio}. The caller * must ensure that @dtc->avail is set before calling this function. The - * dirty limits will be lifted by 1/4 for PF_LESS_THROTTLE (ie. nfsd) and - * real-time tasks. + * dirty limits will be lifted by 1/4 for real-time tasks. */ static void domain_dirty_limits(struct dirty_throttle_control *dtc) { @@ -436,7 +417,7 @@ static void domain_dirty_limits(struct dirty_throttle_control *dtc) if (bg_thresh >= thresh) bg_thresh = thresh / 2; tsk = current; - if (tsk->flags & PF_LESS_THROTTLE || rt_task(tsk)) { + if (rt_task(tsk)) { bg_thresh += bg_thresh / 4 + global_wb_domain.dirty_limit / 32; thresh += thresh / 4 + global_wb_domain.dirty_limit / 32; } @@ -486,7 +467,7 @@ static unsigned long node_dirty_limit(struct pglist_data *pgdat) else dirty = vm_dirty_ratio * node_memory / 100; - if (tsk->flags & PF_LESS_THROTTLE || rt_task(tsk)) + if (rt_task(tsk)) dirty += dirty / 4; return dirty; @@ -505,15 +486,14 @@ bool node_dirty_ok(struct pglist_data *pgdat) unsigned long nr_pages = 0; nr_pages += node_page_state(pgdat, NR_FILE_DIRTY); - nr_pages += node_page_state(pgdat, NR_UNSTABLE_NFS); nr_pages += node_page_state(pgdat, NR_WRITEBACK); return nr_pages <= limit; } -int dirty_background_ratio_handler(struct ctl_table *table, int write, - void __user *buffer, size_t *lenp, - loff_t *ppos) +#ifdef CONFIG_SYSCTL +static int dirty_background_ratio_handler(struct ctl_table *table, int write, + void *buffer, size_t *lenp, loff_t *ppos) { int ret; @@ -523,9 +503,8 @@ int dirty_background_ratio_handler(struct ctl_table *table, int write, return ret; } -int dirty_background_bytes_handler(struct ctl_table *table, int write, - void __user *buffer, size_t *lenp, - loff_t *ppos) +static int dirty_background_bytes_handler(struct ctl_table *table, int write, + void *buffer, size_t *lenp, loff_t *ppos) { int ret; @@ -535,9 +514,8 @@ int dirty_background_bytes_handler(struct ctl_table *table, int write, return ret; } -int dirty_ratio_handler(struct ctl_table *table, int write, - void __user *buffer, size_t *lenp, - loff_t *ppos) +static int dirty_ratio_handler(struct ctl_table *table, int write, void *buffer, + size_t *lenp, loff_t *ppos) { int old_ratio = vm_dirty_ratio; int ret; @@ -550,9 +528,8 @@ int dirty_ratio_handler(struct ctl_table *table, int write, return ret; } -int dirty_bytes_handler(struct ctl_table *table, int write, - void __user *buffer, size_t *lenp, - loff_t *ppos) +static int dirty_bytes_handler(struct ctl_table *table, int write, + void *buffer, size_t *lenp, loff_t *ppos) { unsigned long old_bytes = vm_dirty_bytes; int ret; @@ -564,6 +541,7 @@ int dirty_bytes_handler(struct ctl_table *table, int write, } return ret; } +#endif static unsigned long wp_next_time(unsigned long cur_time) { @@ -574,12 +552,12 @@ static unsigned long wp_next_time(unsigned long cur_time) return cur_time; } -static void wb_domain_writeout_inc(struct wb_domain *dom, +static void wb_domain_writeout_add(struct wb_domain *dom, struct fprop_local_percpu *completions, - unsigned int max_prop_frac) + unsigned int max_prop_frac, long nr) { - __fprop_inc_percpu_max(&dom->completions, completions, - max_prop_frac); + __fprop_add_percpu_max(&dom->completions, completions, + max_prop_frac, nr); /* First event after period switching was turned off? */ if (unlikely(!dom->period_time)) { /* @@ -595,20 +573,20 @@ static void wb_domain_writeout_inc(struct wb_domain *dom, /* * Increment @wb's writeout completion count and the global writeout - * completion count. Called from test_clear_page_writeback(). + * completion count. Called from __folio_end_writeback(). */ -static inline void __wb_writeout_inc(struct bdi_writeback *wb) +static inline void __wb_writeout_add(struct bdi_writeback *wb, long nr) { struct wb_domain *cgdom; - inc_wb_stat(wb, WB_WRITTEN); - wb_domain_writeout_inc(&global_wb_domain, &wb->completions, - wb->bdi->max_prop_frac); + wb_stat_mod(wb, WB_WRITTEN, nr); + wb_domain_writeout_add(&global_wb_domain, &wb->completions, + wb->bdi->max_prop_frac, nr); cgdom = mem_cgroup_wb_domain(wb); if (cgdom) - wb_domain_writeout_inc(cgdom, wb_memcg_completions(wb), - wb->bdi->max_prop_frac); + wb_domain_writeout_add(cgdom, wb_memcg_completions(wb), + wb->bdi->max_prop_frac, nr); } void wb_writeout_inc(struct bdi_writeback *wb) @@ -616,7 +594,7 @@ void wb_writeout_inc(struct bdi_writeback *wb) unsigned long flags; local_irq_save(flags); - __wb_writeout_inc(wb); + __wb_writeout_add(wb, 1); local_irq_restore(flags); } EXPORT_SYMBOL_GPL(wb_writeout_inc); @@ -674,18 +652,25 @@ static unsigned int bdi_min_ratio; int bdi_set_min_ratio(struct backing_dev_info *bdi, unsigned int min_ratio) { + unsigned int delta; int ret = 0; spin_lock_bh(&bdi_lock); if (min_ratio > bdi->max_ratio) { ret = -EINVAL; } else { - min_ratio -= bdi->min_ratio; - if (bdi_min_ratio + min_ratio < 100) { - bdi_min_ratio += min_ratio; - bdi->min_ratio += min_ratio; + if (min_ratio < bdi->min_ratio) { + delta = bdi->min_ratio - min_ratio; + bdi_min_ratio -= delta; + bdi->min_ratio = min_ratio; } else { - ret = -EINVAL; + delta = min_ratio - bdi->min_ratio; + if (bdi_min_ratio + delta < 100) { + bdi_min_ratio += delta; + bdi->min_ratio = min_ratio; + } else { + ret = -EINVAL; + } } } spin_unlock_bh(&bdi_lock); @@ -759,7 +744,7 @@ static void mdtc_calc_avail(struct dirty_throttle_control *mdtc, * bounded by the bdi->min_ratio and/or bdi->max_ratio parameters, if set. * * Return: @wb's dirty limit in pages. The term "dirty" in the context of - * dirty balancing includes all PG_dirty, PG_writeback and NFS unstable pages. + * dirty balancing includes all PG_dirty and PG_writeback pages. */ static unsigned long __wb_calc_thresh(struct dirty_throttle_control *dtc) { @@ -851,7 +836,7 @@ static long long pos_ratio_polynom(unsigned long setpoint, * ^ pos_ratio * | * | |<===== global dirty control scope ======>| - * 2.0 .............* + * 2.0 * * * * * * * * | .* * | . * * | . * @@ -904,7 +889,7 @@ static long long pos_ratio_polynom(unsigned long setpoint, static void wb_position_ratio(struct dirty_throttle_control *dtc) { struct bdi_writeback *wb = dtc->wb; - unsigned long write_bw = wb->avg_write_bandwidth; + unsigned long write_bw = READ_ONCE(wb->avg_write_bandwidth); unsigned long freerun = dirty_freerun_ceiling(dtc->thresh, dtc->bg_thresh); unsigned long limit = hard_dirty_limit(dtc_dom(dtc), dtc->thresh); unsigned long wb_thresh = dtc->wb_thresh; @@ -1096,7 +1081,7 @@ static void wb_update_write_bandwidth(struct bdi_writeback *wb, * write_bandwidth = --------------------------------------------------- * period * - * @written may have decreased due to account_page_redirty(). + * @written may have decreased due to folio_account_redirty(). * Avoid underflowing @bw calculation. */ bw = written - min(written, wb->written_stamp); @@ -1127,7 +1112,7 @@ out: &wb->bdi->tot_write_bandwidth) <= 0); } wb->write_bandwidth = bw; - wb->avg_write_bandwidth = avg; + WRITE_ONCE(wb->avg_write_bandwidth, avg); } static void update_dirty_limit(struct dirty_throttle_control *dtc) @@ -1159,8 +1144,8 @@ update: dom->dirty_limit = limit; } -static void domain_update_bandwidth(struct dirty_throttle_control *dtc, - unsigned long now) +static void domain_update_dirty_limit(struct dirty_throttle_control *dtc, + unsigned long now) { struct wb_domain *dom = dtc_dom(dtc); @@ -1336,7 +1321,7 @@ static void wb_update_dirty_ratelimit(struct dirty_throttle_control *dtc, else dirty_ratelimit -= step; - wb->dirty_ratelimit = max(dirty_ratelimit, 1UL); + WRITE_ONCE(wb->dirty_ratelimit, max(dirty_ratelimit, 1UL)); wb->balanced_dirty_ratelimit = balanced_dirty_ratelimit; trace_bdi_dirty_ratelimit(wb, dirty_rate, task_ratelimit); @@ -1344,35 +1329,28 @@ static void wb_update_dirty_ratelimit(struct dirty_throttle_control *dtc, static void __wb_update_bandwidth(struct dirty_throttle_control *gdtc, struct dirty_throttle_control *mdtc, - unsigned long start_time, bool update_ratelimit) { struct bdi_writeback *wb = gdtc->wb; unsigned long now = jiffies; - unsigned long elapsed = now - wb->bw_time_stamp; + unsigned long elapsed; unsigned long dirtied; unsigned long written; - lockdep_assert_held(&wb->list_lock); + spin_lock(&wb->list_lock); /* - * rate-limit, only update once every 200ms. + * Lockless checks for elapsed time are racy and delayed update after + * IO completion doesn't do it at all (to make sure written pages are + * accounted reasonably quickly). Make sure elapsed >= 1 to avoid + * division errors. */ - if (elapsed < BANDWIDTH_INTERVAL) - return; - + elapsed = max(now - wb->bw_time_stamp, 1UL); dirtied = percpu_counter_read(&wb->stat[WB_DIRTIED]); written = percpu_counter_read(&wb->stat[WB_WRITTEN]); - /* - * Skip quiet periods when disk bandwidth is under-utilized. - * (at least 1s idle time between two flusher runs) - */ - if (elapsed > HZ && time_before(wb->bw_time_stamp, start_time)) - goto snapshot; - if (update_ratelimit) { - domain_update_bandwidth(gdtc, now); + domain_update_dirty_limit(gdtc, now); wb_update_dirty_ratelimit(gdtc, dirtied, elapsed); /* @@ -1380,23 +1358,41 @@ static void __wb_update_bandwidth(struct dirty_throttle_control *gdtc, * compiler has no way to figure that out. Help it. */ if (IS_ENABLED(CONFIG_CGROUP_WRITEBACK) && mdtc) { - domain_update_bandwidth(mdtc, now); + domain_update_dirty_limit(mdtc, now); wb_update_dirty_ratelimit(mdtc, dirtied, elapsed); } } wb_update_write_bandwidth(wb, elapsed, written); -snapshot: wb->dirtied_stamp = dirtied; wb->written_stamp = written; - wb->bw_time_stamp = now; + WRITE_ONCE(wb->bw_time_stamp, now); + spin_unlock(&wb->list_lock); } -void wb_update_bandwidth(struct bdi_writeback *wb, unsigned long start_time) +void wb_update_bandwidth(struct bdi_writeback *wb) { struct dirty_throttle_control gdtc = { GDTC_INIT(wb) }; - __wb_update_bandwidth(&gdtc, NULL, start_time, false); + __wb_update_bandwidth(&gdtc, NULL, false); +} + +/* Interval after which we consider wb idle and don't estimate bandwidth */ +#define WB_BANDWIDTH_IDLE_JIF (HZ) + +static void wb_bandwidth_estimate_start(struct bdi_writeback *wb) +{ + unsigned long now = jiffies; + unsigned long elapsed = now - READ_ONCE(wb->bw_time_stamp); + + if (elapsed > WB_BANDWIDTH_IDLE_JIF && + !atomic_read(&wb->writeback_inodes)) { + spin_lock(&wb->list_lock); + wb->dirtied_stamp = wb_stat(wb, WB_DIRTIED); + wb->written_stamp = wb_stat(wb, WB_WRITTEN); + WRITE_ONCE(wb->bw_time_stamp, now); + spin_unlock(&wb->list_lock); + } } /* @@ -1419,7 +1415,7 @@ static unsigned long dirty_poll_interval(unsigned long dirty, static unsigned long wb_max_pause(struct bdi_writeback *wb, unsigned long wb_dirty) { - unsigned long bw = wb->avg_write_bandwidth; + unsigned long bw = READ_ONCE(wb->avg_write_bandwidth); unsigned long t; /* @@ -1441,8 +1437,8 @@ static long wb_min_pause(struct bdi_writeback *wb, unsigned long dirty_ratelimit, int *nr_dirtied_pause) { - long hi = ilog2(wb->avg_write_bandwidth); - long lo = ilog2(wb->dirty_ratelimit); + long hi = ilog2(READ_ONCE(wb->avg_write_bandwidth)); + long lo = ilog2(READ_ONCE(wb->dirty_ratelimit)); long t; /* target pause */ long pause; /* estimated next pause */ int pages; /* target nr_dirtied_pause */ @@ -1558,8 +1554,8 @@ static inline void wb_dirty_limits(struct dirty_throttle_control *dtc) * If we're over `background_thresh' then the writeback threads are woken to * perform some writeout. */ -static void balance_dirty_pages(struct bdi_writeback *wb, - unsigned long pages_dirtied) +static int balance_dirty_pages(struct bdi_writeback *wb, + unsigned long pages_dirtied, unsigned int flags) { struct dirty_throttle_control gdtc_stor = { GDTC_INIT(wb) }; struct dirty_throttle_control mdtc_stor = { MDTC_INIT(wb, &gdtc_stor) }; @@ -1567,7 +1563,7 @@ static void balance_dirty_pages(struct bdi_writeback *wb, struct dirty_throttle_control * const mdtc = mdtc_valid(&mdtc_stor) ? &mdtc_stor : NULL; struct dirty_throttle_control *sdtc; - unsigned long nr_reclaimable; /* = file_dirty + unstable_nfs */ + unsigned long nr_reclaimable; /* = file_dirty */ long period; long pause; long max_pause; @@ -1579,6 +1575,7 @@ static void balance_dirty_pages(struct bdi_writeback *wb, struct backing_dev_info *bdi = wb->bdi; bool strictlimit = bdi->capabilities & BDI_CAP_STRICTLIMIT; unsigned long start_time = jiffies; + int ret = 0; for (;;) { unsigned long now = jiffies; @@ -1587,14 +1584,7 @@ static void balance_dirty_pages(struct bdi_writeback *wb, unsigned long m_thresh = 0; unsigned long m_bg_thresh = 0; - /* - * Unstable writes are a feature of certain networked - * filesystems (i.e. NFS) in which data may have been - * written to the server's write cache, but has not yet - * been flushed to permanent storage. - */ - nr_reclaimable = global_node_page_state(NR_FILE_DIRTY) + - global_node_page_state(NR_UNSTABLE_NFS); + nr_reclaimable = global_node_page_state(NR_FILE_DIRTY); gdtc->avail = global_dirtyable_memory(); gdtc->dirty = nr_reclaimable + global_node_page_state(NR_WRITEBACK); @@ -1639,6 +1629,19 @@ static void balance_dirty_pages(struct bdi_writeback *wb, } /* + * In laptop mode, we wait until hitting the higher threshold + * before starting background writeout, and then write out all + * the way down to the lower threshold. So slow writers cause + * minimal disk activity. + * + * In normal mode, we start background writeout at the lower + * background_thresh, to keep the amount of dirty memory low. + */ + if (!laptop_mode && nr_reclaimable > gdtc->bg_thresh && + !writeback_in_progress(wb)) + wb_start_background_writeback(wb); + + /* * Throttle it only when the background writeback cannot * catch-up. This avoids (excessively) small writeouts * when the wb limits are ramping up in case of !strictlimit. @@ -1653,8 +1656,12 @@ static void balance_dirty_pages(struct bdi_writeback *wb, if (dirty <= dirty_freerun_ceiling(thresh, bg_thresh) && (!mdtc || m_dirty <= dirty_freerun_ceiling(m_thresh, m_bg_thresh))) { - unsigned long intv = dirty_poll_interval(dirty, thresh); - unsigned long m_intv = ULONG_MAX; + unsigned long intv; + unsigned long m_intv; + +free_running: + intv = dirty_poll_interval(dirty, thresh); + m_intv = ULONG_MAX; current->dirty_paused_when = now; current->nr_dirtied = 0; @@ -1664,6 +1671,7 @@ static void balance_dirty_pages(struct bdi_writeback *wb, break; } + /* Start writeback even when in laptop mode */ if (unlikely(!writeback_in_progress(wb))) wb_start_background_writeback(wb); @@ -1673,9 +1681,20 @@ static void balance_dirty_pages(struct bdi_writeback *wb, * Calculate global domain's pos_ratio and select the * global dtc by default. */ - if (!strictlimit) + if (!strictlimit) { wb_dirty_limits(gdtc); + if ((current->flags & PF_LOCAL_THROTTLE) && + gdtc->wb_dirty < + dirty_freerun_ceiling(gdtc->wb_thresh, + gdtc->wb_bg_thresh)) + /* + * LOCAL_THROTTLE tasks must not be throttled + * when below the per-wb freerun ceiling. + */ + goto free_running; + } + dirty_exceeded = (gdtc->wb_dirty > gdtc->wb_thresh) && ((gdtc->dirty > gdtc->thresh) || strictlimit); @@ -1689,9 +1708,20 @@ static void balance_dirty_pages(struct bdi_writeback *wb, * both global and memcg domains. Choose the one * w/ lower pos_ratio. */ - if (!strictlimit) + if (!strictlimit) { wb_dirty_limits(mdtc); + if ((current->flags & PF_LOCAL_THROTTLE) && + mdtc->wb_dirty < + dirty_freerun_ceiling(mdtc->wb_thresh, + mdtc->wb_bg_thresh)) + /* + * LOCAL_THROTTLE tasks must not be + * throttled when below the per-wb + * freerun ceiling. + */ + goto free_running; + } dirty_exceeded |= (mdtc->wb_dirty > mdtc->wb_thresh) && ((mdtc->dirty > mdtc->thresh) || strictlimit); @@ -1700,18 +1730,15 @@ static void balance_dirty_pages(struct bdi_writeback *wb, sdtc = mdtc; } - if (dirty_exceeded && !wb->dirty_exceeded) - wb->dirty_exceeded = 1; + if (dirty_exceeded != wb->dirty_exceeded) + wb->dirty_exceeded = dirty_exceeded; - if (time_is_before_jiffies(wb->bw_time_stamp + - BANDWIDTH_INTERVAL)) { - spin_lock(&wb->list_lock); - __wb_update_bandwidth(gdtc, mdtc, start_time, true); - spin_unlock(&wb->list_lock); - } + if (time_is_before_jiffies(READ_ONCE(wb->bw_time_stamp) + + BANDWIDTH_INTERVAL)) + __wb_update_bandwidth(gdtc, mdtc, true); /* throttle according to the chosen dtc */ - dirty_ratelimit = wb->dirty_ratelimit; + dirty_ratelimit = READ_ONCE(wb->dirty_ratelimit); task_ratelimit = ((u64)dirty_ratelimit * sdtc->pos_ratio) >> RATELIMIT_CALC_SHIFT; max_pause = wb_max_pause(wb, sdtc->wb_dirty); @@ -1777,6 +1804,10 @@ pause: period, pause, start_time); + if (flags & BDP_ASYNC) { + ret = -EAGAIN; + break; + } __set_current_state(TASK_KILLABLE); wb->dirty_sleep = now; io_schedule_timeout(pause); @@ -1793,7 +1824,7 @@ pause: break; /* - * In the case of an unresponding NFS server and the NFS dirty + * In the case of an unresponsive NFS server and the NFS dirty * pages exceeds dirty_thresh, give the other good wb's a pipe * to go through, so that tasks on them still remain responsive. * @@ -1808,26 +1839,7 @@ pause: if (fatal_signal_pending(current)) break; } - - if (!dirty_exceeded && wb->dirty_exceeded) - wb->dirty_exceeded = 0; - - if (writeback_in_progress(wb)) - return; - - /* - * In laptop mode, we wait until hitting the higher threshold before - * starting background writeout, and then write out all the way down - * to the lower threshold. So slow writers cause minimal disk activity. - * - * In normal mode, we start background writeout at the lower - * background_thresh, to keep the amount of dirty memory low. - */ - if (laptop_mode) - return; - - if (nr_reclaimable > gdtc->bg_thresh) - wb_start_background_writeback(wb); + return ret; } static DEFINE_PER_CPU(int, bdp_ratelimits); @@ -1849,28 +1861,34 @@ static DEFINE_PER_CPU(int, bdp_ratelimits); DEFINE_PER_CPU(int, dirty_throttle_leaks) = 0; /** - * balance_dirty_pages_ratelimited - balance dirty memory state - * @mapping: address_space which was dirtied + * balance_dirty_pages_ratelimited_flags - Balance dirty memory state. + * @mapping: address_space which was dirtied. + * @flags: BDP flags. * * Processes which are dirtying memory should call in here once for each page * which was newly dirtied. The function will periodically check the system's * dirty state and will initiate writeback if needed. * - * On really big machines, get_writeback_state is expensive, so try to avoid - * calling it too often (ratelimiting). But once we're over the dirty memory - * limit we decrease the ratelimiting by a lot, to prevent individual processes - * from overshooting the limit by (ratelimit_pages) each. + * See balance_dirty_pages_ratelimited() for details. + * + * Return: If @flags contains BDP_ASYNC, it may return -EAGAIN to + * indicate that memory is out of balance and the caller must wait + * for I/O to complete. Otherwise, it will return 0 to indicate + * that either memory was already in balance, or it was able to sleep + * until the amount of dirty memory returned to balance. */ -void balance_dirty_pages_ratelimited(struct address_space *mapping) +int balance_dirty_pages_ratelimited_flags(struct address_space *mapping, + unsigned int flags) { struct inode *inode = mapping->host; struct backing_dev_info *bdi = inode_to_bdi(inode); struct bdi_writeback *wb = NULL; int ratelimit; + int ret = 0; int *p; - if (!bdi_cap_account_dirty(bdi)) - return; + if (!(bdi->capabilities & BDI_CAP_WRITEBACK)) + return ret; if (inode_cgwb_enabled(inode)) wb = wb_get_create_current(bdi, GFP_KERNEL); @@ -1910,9 +1928,28 @@ void balance_dirty_pages_ratelimited(struct address_space *mapping) preempt_enable(); if (unlikely(current->nr_dirtied >= ratelimit)) - balance_dirty_pages(wb, current->nr_dirtied); + ret = balance_dirty_pages(wb, current->nr_dirtied, flags); wb_put(wb); + return ret; +} +EXPORT_SYMBOL_GPL(balance_dirty_pages_ratelimited_flags); + +/** + * balance_dirty_pages_ratelimited - balance dirty memory state. + * @mapping: address_space which was dirtied. + * + * Processes which are dirtying memory should call in here once for each page + * which was newly dirtied. The function will periodically check the system's + * dirty state and will initiate writeback if needed. + * + * Once we're over the dirty memory limit we decrease the ratelimiting + * by a lot, to prevent individual processes from overshooting the limit + * by (ratelimit_pages) each. + */ +void balance_dirty_pages_ratelimited(struct address_space *mapping) +{ + balance_dirty_pages_ratelimited_flags(mapping, 0); } EXPORT_SYMBOL(balance_dirty_pages_ratelimited); @@ -1932,21 +1969,27 @@ bool wb_over_bg_thresh(struct bdi_writeback *wb) struct dirty_throttle_control * const gdtc = &gdtc_stor; struct dirty_throttle_control * const mdtc = mdtc_valid(&mdtc_stor) ? &mdtc_stor : NULL; + unsigned long reclaimable; + unsigned long thresh; /* * Similar to balance_dirty_pages() but ignores pages being written * as we're trying to decide whether to put more under writeback. */ gdtc->avail = global_dirtyable_memory(); - gdtc->dirty = global_node_page_state(NR_FILE_DIRTY) + - global_node_page_state(NR_UNSTABLE_NFS); + gdtc->dirty = global_node_page_state(NR_FILE_DIRTY); domain_dirty_limits(gdtc); if (gdtc->dirty > gdtc->bg_thresh) return true; - if (wb_stat(wb, WB_RECLAIMABLE) > - wb_calc_thresh(gdtc->wb, gdtc->bg_thresh)) + thresh = wb_calc_thresh(gdtc->wb, gdtc->bg_thresh); + if (thresh < 2 * wb_stat_error()) + reclaimable = wb_stat_sum(wb, WB_RECLAIMABLE); + else + reclaimable = wb_stat(wb, WB_RECLAIMABLE); + + if (reclaimable > thresh) return true; if (mdtc) { @@ -1960,19 +2003,25 @@ bool wb_over_bg_thresh(struct bdi_writeback *wb) if (mdtc->dirty > mdtc->bg_thresh) return true; - if (wb_stat(wb, WB_RECLAIMABLE) > - wb_calc_thresh(mdtc->wb, mdtc->bg_thresh)) + thresh = wb_calc_thresh(mdtc->wb, mdtc->bg_thresh); + if (thresh < 2 * wb_stat_error()) + reclaimable = wb_stat_sum(wb, WB_RECLAIMABLE); + else + reclaimable = wb_stat(wb, WB_RECLAIMABLE); + + if (reclaimable > thresh) return true; } return false; } +#ifdef CONFIG_SYSCTL /* * sysctl handler for /proc/sys/vm/dirty_writeback_centisecs */ -int dirty_writeback_centisecs_handler(struct ctl_table *table, int write, - void __user *buffer, size_t *length, loff_t *ppos) +static int dirty_writeback_centisecs_handler(struct ctl_table *table, int write, + void *buffer, size_t *length, loff_t *ppos) { unsigned int old_interval = dirty_writeback_interval; int ret; @@ -1992,8 +2041,8 @@ int dirty_writeback_centisecs_handler(struct ctl_table *table, int write, return ret; } +#endif -#ifdef CONFIG_BLOCK void laptop_mode_timer_fn(struct timer_list *t) { struct backing_dev_info *backing_dev_info = @@ -2028,13 +2077,10 @@ void laptop_sync_completion(void) rcu_read_unlock(); } -#endif /* * If ratelimit_pages is too high then we can get into dirty-data overload * if a large number of processes all perform writes at the same time. - * If it is too low then SMP machines will call the (expensive) - * get_writeback_state too often. * * Here we set ratelimit_pages to a level which ensures that when all CPUs are * dirtying in parallel, we cannot go more than 3% (1/32) over the dirty memory @@ -2060,17 +2106,92 @@ static int page_writeback_cpu_online(unsigned int cpu) return 0; } +#ifdef CONFIG_SYSCTL + +/* this is needed for the proc_doulongvec_minmax of vm_dirty_bytes */ +static const unsigned long dirty_bytes_min = 2 * PAGE_SIZE; + +static struct ctl_table vm_page_writeback_sysctls[] = { + { + .procname = "dirty_background_ratio", + .data = &dirty_background_ratio, + .maxlen = sizeof(dirty_background_ratio), + .mode = 0644, + .proc_handler = dirty_background_ratio_handler, + .extra1 = SYSCTL_ZERO, + .extra2 = SYSCTL_ONE_HUNDRED, + }, + { + .procname = "dirty_background_bytes", + .data = &dirty_background_bytes, + .maxlen = sizeof(dirty_background_bytes), + .mode = 0644, + .proc_handler = dirty_background_bytes_handler, + .extra1 = SYSCTL_LONG_ONE, + }, + { + .procname = "dirty_ratio", + .data = &vm_dirty_ratio, + .maxlen = sizeof(vm_dirty_ratio), + .mode = 0644, + .proc_handler = dirty_ratio_handler, + .extra1 = SYSCTL_ZERO, + .extra2 = SYSCTL_ONE_HUNDRED, + }, + { + .procname = "dirty_bytes", + .data = &vm_dirty_bytes, + .maxlen = sizeof(vm_dirty_bytes), + .mode = 0644, + .proc_handler = dirty_bytes_handler, + .extra1 = (void *)&dirty_bytes_min, + }, + { + .procname = "dirty_writeback_centisecs", + .data = &dirty_writeback_interval, + .maxlen = sizeof(dirty_writeback_interval), + .mode = 0644, + .proc_handler = dirty_writeback_centisecs_handler, + }, + { + .procname = "dirty_expire_centisecs", + .data = &dirty_expire_interval, + .maxlen = sizeof(dirty_expire_interval), + .mode = 0644, + .proc_handler = proc_dointvec_minmax, + .extra1 = SYSCTL_ZERO, + }, +#ifdef CONFIG_HIGHMEM + { + .procname = "highmem_is_dirtyable", + .data = &vm_highmem_is_dirtyable, + .maxlen = sizeof(vm_highmem_is_dirtyable), + .mode = 0644, + .proc_handler = proc_dointvec_minmax, + .extra1 = SYSCTL_ZERO, + .extra2 = SYSCTL_ONE, + }, +#endif + { + .procname = "laptop_mode", + .data = &laptop_mode, + .maxlen = sizeof(laptop_mode), + .mode = 0644, + .proc_handler = proc_dointvec_jiffies, + }, + {} +}; +#endif + /* * Called early on to tune the page writeback dirty limits. * * We used to scale dirty pages according to how total memory - * related to pages that could be allocated for buffers (by - * comparing nr_free_buffer_pages() to vm_total_pages. + * related to pages that could be allocated for buffers. * * However, that was when we used "dirty_ratio" to scale with * all memory, and we don't do that any more. "dirty_ratio" - * is now applied to total non-HIGHPAGE memory (by subtracting - * totalhigh_pages from vm_total_pages), and as such we can't + * is now applied to total non-HIGHPAGE memory, and as such we can't * get into the old insane situation any more where we had * large amounts of dirty pages compared to a small amount of * non-HIGHMEM memory. @@ -2086,6 +2207,9 @@ void __init page_writeback_init(void) page_writeback_cpu_online, NULL); cpuhp_setup_state(CPUHP_MM_WRITEBACK_DEAD, "mm/writeback:dead", NULL, page_writeback_cpu_online); +#ifdef CONFIG_SYSCTL + register_sysctl_init("vm", vm_page_writeback_sysctls); +#endif } /** @@ -2164,7 +2288,6 @@ int write_cache_pages(struct address_space *mapping, int error; struct pagevec pvec; int nr_pages; - pgoff_t uninitialized_var(writeback_index); pgoff_t index; pgoff_t end; /* Inclusive */ pgoff_t done_index; @@ -2173,8 +2296,7 @@ int write_cache_pages(struct address_space *mapping, pagevec_init(&pvec); if (wbc->range_cyclic) { - writeback_index = mapping->writeback_index; /* prev offset */ - index = writeback_index; + index = mapping->writeback_index; /* prev offset */ end = -1; } else { index = wbc->range_start >> PAGE_SHIFT; @@ -2182,12 +2304,12 @@ int write_cache_pages(struct address_space *mapping, if (wbc->range_start == 0 && wbc->range_end == LLONG_MAX) range_whole = 1; } - if (wbc->sync_mode == WB_SYNC_ALL || wbc->tagged_writepages) + if (wbc->sync_mode == WB_SYNC_ALL || wbc->tagged_writepages) { + tag_pages_for_writeback(mapping, index, end); tag = PAGECACHE_TAG_TOWRITE; - else + } else { tag = PAGECACHE_TAG_DIRTY; - if (wbc->sync_mode == WB_SYNC_ALL || wbc->tagged_writepages) - tag_pages_for_writeback(mapping, index, end); + } done_index = index; while (!done && (index <= end)) { int i; @@ -2208,7 +2330,7 @@ int write_cache_pages(struct address_space *mapping, * Page truncated or invalidated. We can freely skip it * then, even for data integrity operations: the page * has disappeared concurrently, so there could be no - * real expectation of this data interity operation + * real expectation of this data integrity operation * even if there is now a new, dirty page at the same * pagecache address. */ @@ -2336,9 +2458,12 @@ EXPORT_SYMBOL(generic_writepages); int do_writepages(struct address_space *mapping, struct writeback_control *wbc) { int ret; + struct bdi_writeback *wb; if (wbc->nr_to_write <= 0) return 0; + wb = inode_to_wb_wbc(mapping->host, wbc); + wb_bandwidth_estimate_start(wb); while (1) { if (mapping->a_ops->writepages) ret = mapping->a_ops->writepages(mapping, wbc); @@ -2346,61 +2471,77 @@ int do_writepages(struct address_space *mapping, struct writeback_control *wbc) ret = generic_writepages(mapping, wbc); if ((ret != -ENOMEM) || (wbc->sync_mode != WB_SYNC_ALL)) break; - cond_resched(); - congestion_wait(BLK_RW_ASYNC, HZ/50); + + /* + * Lacking an allocation context or the locality or writeback + * state of any of the inode's pages, throttle based on + * writeback activity on the local node. It's as good a + * guess as any. + */ + reclaim_throttle(NODE_DATA(numa_node_id()), + VMSCAN_THROTTLE_WRITEBACK); } + /* + * Usually few pages are written by now from those we've just submitted + * but if there's constant writeback being submitted, this makes sure + * writeback bandwidth is updated once in a while. + */ + if (time_is_before_jiffies(READ_ONCE(wb->bw_time_stamp) + + BANDWIDTH_INTERVAL)) + wb_update_bandwidth(wb); return ret; } /** - * write_one_page - write out a single page and wait on I/O - * @page: the page to write + * folio_write_one - write out a single folio and wait on I/O. + * @folio: The folio to write. * - * The page must be locked by the caller and will be unlocked upon return. + * The folio must be locked by the caller and will be unlocked upon return. * * Note that the mapping's AS_EIO/AS_ENOSPC flags will be cleared when this * function returns. * * Return: %0 on success, negative error code otherwise */ -int write_one_page(struct page *page) +int folio_write_one(struct folio *folio) { - struct address_space *mapping = page->mapping; + struct address_space *mapping = folio->mapping; int ret = 0; struct writeback_control wbc = { .sync_mode = WB_SYNC_ALL, - .nr_to_write = 1, + .nr_to_write = folio_nr_pages(folio), }; - BUG_ON(!PageLocked(page)); + BUG_ON(!folio_test_locked(folio)); - wait_on_page_writeback(page); + folio_wait_writeback(folio); - if (clear_page_dirty_for_io(page)) { - get_page(page); - ret = mapping->a_ops->writepage(page, &wbc); + if (folio_clear_dirty_for_io(folio)) { + folio_get(folio); + ret = mapping->a_ops->writepage(&folio->page, &wbc); if (ret == 0) - wait_on_page_writeback(page); - put_page(page); + folio_wait_writeback(folio); + folio_put(folio); } else { - unlock_page(page); + folio_unlock(folio); } if (!ret) ret = filemap_check_errors(mapping); return ret; } -EXPORT_SYMBOL(write_one_page); +EXPORT_SYMBOL(folio_write_one); /* * For address_spaces which do not use buffers nor write back. */ -int __set_page_dirty_no_writeback(struct page *page) +bool noop_dirty_folio(struct address_space *mapping, struct folio *folio) { - if (!PageDirty(page)) - return !TestSetPageDirty(page); - return 0; + if (!folio_test_dirty(folio)) + return !folio_test_set_dirty(folio); + return false; } +EXPORT_SYMBOL(noop_dirty_folio); /* * Helper function for set_page_dirty family. @@ -2409,28 +2550,30 @@ int __set_page_dirty_no_writeback(struct page *page) * * NOTE: This relies on being atomic wrt interrupts. */ -void account_page_dirtied(struct page *page, struct address_space *mapping) +static void folio_account_dirtied(struct folio *folio, + struct address_space *mapping) { struct inode *inode = mapping->host; - trace_writeback_dirty_page(page, mapping); + trace_writeback_dirty_folio(folio, mapping); - if (mapping_cap_account_dirty(mapping)) { + if (mapping_can_writeback(mapping)) { struct bdi_writeback *wb; + long nr = folio_nr_pages(folio); - inode_attach_wb(inode, page); + inode_attach_wb(inode, &folio->page); wb = inode_to_wb(inode); - __inc_lruvec_page_state(page, NR_FILE_DIRTY); - __inc_zone_page_state(page, NR_ZONE_WRITE_PENDING); - __inc_node_page_state(page, NR_DIRTIED); - inc_wb_stat(wb, WB_RECLAIMABLE); - inc_wb_stat(wb, WB_DIRTIED); - task_io_account_write(PAGE_SIZE); - current->nr_dirtied++; - this_cpu_inc(bdp_ratelimits); + __lruvec_stat_mod_folio(folio, NR_FILE_DIRTY, nr); + __zone_stat_mod_folio(folio, NR_ZONE_WRITE_PENDING, nr); + __node_stat_mod_folio(folio, NR_DIRTIED, nr); + wb_stat_mod(wb, WB_RECLAIMABLE, nr); + wb_stat_mod(wb, WB_DIRTIED, nr); + task_io_account_write(nr * PAGE_SIZE); + current->nr_dirtied += nr; + __this_cpu_add(bdp_ratelimits, nr); - mem_cgroup_track_foreign_dirty(page, wb); + mem_cgroup_track_foreign_dirty(folio, wb); } } @@ -2439,145 +2582,176 @@ void account_page_dirtied(struct page *page, struct address_space *mapping) * * Caller must hold lock_page_memcg(). */ -void account_page_cleaned(struct page *page, struct address_space *mapping, - struct bdi_writeback *wb) -{ - if (mapping_cap_account_dirty(mapping)) { - dec_lruvec_page_state(page, NR_FILE_DIRTY); - dec_zone_page_state(page, NR_ZONE_WRITE_PENDING); - dec_wb_stat(wb, WB_RECLAIMABLE); - task_io_account_cancelled_write(PAGE_SIZE); - } +void folio_account_cleaned(struct folio *folio, struct bdi_writeback *wb) +{ + long nr = folio_nr_pages(folio); + + lruvec_stat_mod_folio(folio, NR_FILE_DIRTY, -nr); + zone_stat_mod_folio(folio, NR_ZONE_WRITE_PENDING, -nr); + wb_stat_mod(wb, WB_RECLAIMABLE, -nr); + task_io_account_cancelled_write(nr * PAGE_SIZE); } /* - * For address_spaces which do not use buffers. Just tag the page as dirty in - * the xarray. + * Mark the folio dirty, and set it dirty in the page cache, and mark + * the inode dirty. * - * This is also used when a single buffer is being dirtied: we want to set the - * page dirty in that case, but not all the buffers. This is a "bottom-up" - * dirtying, whereas __set_page_dirty_buffers() is a "top-down" dirtying. + * If warn is true, then emit a warning if the folio is not uptodate and has + * not been truncated. * - * The caller must ensure this doesn't race with truncation. Most will simply - * hold the page lock, but e.g. zap_pte_range() calls with the page mapped and - * the pte lock held, which also locks out truncation. + * The caller must hold lock_page_memcg(). Most callers have the folio + * locked. A few have the folio blocked from truncation through other + * means (eg zap_page_range() has it mapped and is holding the page table + * lock). This can also be called from mark_buffer_dirty(), which I + * cannot prove is always protected against truncate. */ -int __set_page_dirty_nobuffers(struct page *page) +void __folio_mark_dirty(struct folio *folio, struct address_space *mapping, + int warn) { - lock_page_memcg(page); - if (!TestSetPageDirty(page)) { - struct address_space *mapping = page_mapping(page); - unsigned long flags; + unsigned long flags; - if (!mapping) { - unlock_page_memcg(page); - return 1; - } + xa_lock_irqsave(&mapping->i_pages, flags); + if (folio->mapping) { /* Race with truncate? */ + WARN_ON_ONCE(warn && !folio_test_uptodate(folio)); + folio_account_dirtied(folio, mapping); + __xa_set_mark(&mapping->i_pages, folio_index(folio), + PAGECACHE_TAG_DIRTY); + } + xa_unlock_irqrestore(&mapping->i_pages, flags); +} - xa_lock_irqsave(&mapping->i_pages, flags); - BUG_ON(page_mapping(page) != mapping); - WARN_ON_ONCE(!PagePrivate(page) && !PageUptodate(page)); - account_page_dirtied(page, mapping); - __xa_set_mark(&mapping->i_pages, page_index(page), - PAGECACHE_TAG_DIRTY); - xa_unlock_irqrestore(&mapping->i_pages, flags); - unlock_page_memcg(page); +/** + * filemap_dirty_folio - Mark a folio dirty for filesystems which do not use buffer_heads. + * @mapping: Address space this folio belongs to. + * @folio: Folio to be marked as dirty. + * + * Filesystems which do not use buffer heads should call this function + * from their set_page_dirty address space operation. It ignores the + * contents of folio_get_private(), so if the filesystem marks individual + * blocks as dirty, the filesystem should handle that itself. + * + * This is also sometimes used by filesystems which use buffer_heads when + * a single buffer is being dirtied: we want to set the folio dirty in + * that case, but not all the buffers. This is a "bottom-up" dirtying, + * whereas block_dirty_folio() is a "top-down" dirtying. + * + * The caller must ensure this doesn't race with truncation. Most will + * simply hold the folio lock, but e.g. zap_pte_range() calls with the + * folio mapped and the pte lock held, which also locks out truncation. + */ +bool filemap_dirty_folio(struct address_space *mapping, struct folio *folio) +{ + folio_memcg_lock(folio); + if (folio_test_set_dirty(folio)) { + folio_memcg_unlock(folio); + return false; + } - if (mapping->host) { - /* !PageAnon && !swapper_space */ - __mark_inode_dirty(mapping->host, I_DIRTY_PAGES); - } - return 1; + __folio_mark_dirty(folio, mapping, !folio_test_private(folio)); + folio_memcg_unlock(folio); + + if (mapping->host) { + /* !PageAnon && !swapper_space */ + __mark_inode_dirty(mapping->host, I_DIRTY_PAGES); } - unlock_page_memcg(page); - return 0; + return true; } -EXPORT_SYMBOL(__set_page_dirty_nobuffers); +EXPORT_SYMBOL(filemap_dirty_folio); -/* - * Call this whenever redirtying a page, to de-account the dirty counters - * (NR_DIRTIED, WB_DIRTIED, tsk->nr_dirtied), so that they match the written - * counters (NR_WRITTEN, WB_WRITTEN) in long term. The mismatches will lead to - * systematic errors in balanced_dirty_ratelimit and the dirty pages position - * control. +/** + * folio_account_redirty - Manually account for redirtying a page. + * @folio: The folio which is being redirtied. + * + * Most filesystems should call folio_redirty_for_writepage() instead + * of this fuction. If your filesystem is doing writeback outside the + * context of a writeback_control(), it can call this when redirtying + * a folio, to de-account the dirty counters (NR_DIRTIED, WB_DIRTIED, + * tsk->nr_dirtied), so that they match the written counters (NR_WRITTEN, + * WB_WRITTEN) in long term. The mismatches will lead to systematic errors + * in balanced_dirty_ratelimit and the dirty pages position control. */ -void account_page_redirty(struct page *page) +void folio_account_redirty(struct folio *folio) { - struct address_space *mapping = page->mapping; + struct address_space *mapping = folio->mapping; - if (mapping && mapping_cap_account_dirty(mapping)) { + if (mapping && mapping_can_writeback(mapping)) { struct inode *inode = mapping->host; struct bdi_writeback *wb; struct wb_lock_cookie cookie = {}; + long nr = folio_nr_pages(folio); wb = unlocked_inode_to_wb_begin(inode, &cookie); - current->nr_dirtied--; - dec_node_page_state(page, NR_DIRTIED); - dec_wb_stat(wb, WB_DIRTIED); + current->nr_dirtied -= nr; + node_stat_mod_folio(folio, NR_DIRTIED, -nr); + wb_stat_mod(wb, WB_DIRTIED, -nr); unlocked_inode_to_wb_end(inode, &cookie); } } -EXPORT_SYMBOL(account_page_redirty); +EXPORT_SYMBOL(folio_account_redirty); -/* - * When a writepage implementation decides that it doesn't want to write this - * page for some reason, it should redirty the locked page via - * redirty_page_for_writepage() and it should then unlock the page and return 0 +/** + * folio_redirty_for_writepage - Decline to write a dirty folio. + * @wbc: The writeback control. + * @folio: The folio. + * + * When a writepage implementation decides that it doesn't want to write + * @folio for some reason, it should call this function, unlock @folio and + * return 0. + * + * Return: True if we redirtied the folio. False if someone else dirtied + * it first. */ -int redirty_page_for_writepage(struct writeback_control *wbc, struct page *page) +bool folio_redirty_for_writepage(struct writeback_control *wbc, + struct folio *folio) { - int ret; + bool ret; + long nr = folio_nr_pages(folio); + + wbc->pages_skipped += nr; + ret = filemap_dirty_folio(folio->mapping, folio); + folio_account_redirty(folio); - wbc->pages_skipped++; - ret = __set_page_dirty_nobuffers(page); - account_page_redirty(page); return ret; } -EXPORT_SYMBOL(redirty_page_for_writepage); +EXPORT_SYMBOL(folio_redirty_for_writepage); -/* - * Dirty a page. +/** + * folio_mark_dirty - Mark a folio as being modified. + * @folio: The folio. * - * For pages with a mapping this should be done under the page lock - * for the benefit of asynchronous memory errors who prefer a consistent - * dirty state. This rule can be broken in some special cases, - * but should be better not to. + * The folio may not be truncated while this function is running. + * Holding the folio lock is sufficient to prevent truncation, but some + * callers cannot acquire a sleeping lock. These callers instead hold + * the page table lock for a page table which contains at least one page + * in this folio. Truncation will block on the page table lock as it + * unmaps pages before removing the folio from its mapping. * - * If the mapping doesn't provide a set_page_dirty a_op, then - * just fall through and assume that it wants buffer_heads. + * Return: True if the folio was newly dirtied, false if it was already dirty. */ -int set_page_dirty(struct page *page) +bool folio_mark_dirty(struct folio *folio) { - struct address_space *mapping = page_mapping(page); + struct address_space *mapping = folio_mapping(folio); - page = compound_head(page); if (likely(mapping)) { - int (*spd)(struct page *) = mapping->a_ops->set_page_dirty; /* * readahead/lru_deactivate_page could remain - * PG_readahead/PG_reclaim due to race with end_page_writeback - * About readahead, if the page is written, the flags would be + * PG_readahead/PG_reclaim due to race with folio_end_writeback + * About readahead, if the folio is written, the flags would be * reset. So no problem. - * About lru_deactivate_page, if the page is redirty, the flag - * will be reset. So no problem. but if the page is used by readahead - * it will confuse readahead and make it restart the size rampup - * process. But it's a trivial problem. + * About lru_deactivate_page, if the folio is redirtied, + * the flag will be reset. So no problem. but if the + * folio is used by readahead it will confuse readahead + * and make it restart the size rampup process. But it's + * a trivial problem. */ - if (PageReclaim(page)) - ClearPageReclaim(page); -#ifdef CONFIG_BLOCK - if (!spd) - spd = __set_page_dirty_buffers; -#endif - return (*spd)(page); - } - if (!PageDirty(page)) { - if (!TestSetPageDirty(page)) - return 1; + if (folio_test_reclaim(folio)) + folio_clear_reclaim(folio); + return mapping->a_ops->dirty_folio(mapping, folio); } - return 0; + + return noop_dirty_folio(mapping, folio); } -EXPORT_SYMBOL(set_page_dirty); +EXPORT_SYMBOL(folio_mark_dirty); /* * set_page_dirty() is racy if the caller has no reference against @@ -2613,51 +2787,51 @@ EXPORT_SYMBOL(set_page_dirty_lock); * page without actually doing it through the VM. Can you say "ext3 is * horribly ugly"? Thought you could. */ -void __cancel_dirty_page(struct page *page) +void __folio_cancel_dirty(struct folio *folio) { - struct address_space *mapping = page_mapping(page); + struct address_space *mapping = folio_mapping(folio); - if (mapping_cap_account_dirty(mapping)) { + if (mapping_can_writeback(mapping)) { struct inode *inode = mapping->host; struct bdi_writeback *wb; struct wb_lock_cookie cookie = {}; - lock_page_memcg(page); + folio_memcg_lock(folio); wb = unlocked_inode_to_wb_begin(inode, &cookie); - if (TestClearPageDirty(page)) - account_page_cleaned(page, mapping, wb); + if (folio_test_clear_dirty(folio)) + folio_account_cleaned(folio, wb); unlocked_inode_to_wb_end(inode, &cookie); - unlock_page_memcg(page); + folio_memcg_unlock(folio); } else { - ClearPageDirty(page); + folio_clear_dirty(folio); } } -EXPORT_SYMBOL(__cancel_dirty_page); +EXPORT_SYMBOL(__folio_cancel_dirty); /* - * Clear a page's dirty flag, while caring for dirty memory accounting. - * Returns true if the page was previously dirty. - * - * This is for preparing to put the page under writeout. We leave the page - * tagged as dirty in the xarray so that a concurrent write-for-sync - * can discover it via a PAGECACHE_TAG_DIRTY walk. The ->writepage - * implementation will run either set_page_writeback() or set_page_dirty(), - * at which stage we bring the page's dirty flag and xarray dirty tag - * back into sync. - * - * This incoherency between the page's dirty flag and xarray tag is - * unfortunate, but it only exists while the page is locked. + * Clear a folio's dirty flag, while caring for dirty memory accounting. + * Returns true if the folio was previously dirty. + * + * This is for preparing to put the folio under writeout. We leave + * the folio tagged as dirty in the xarray so that a concurrent + * write-for-sync can discover it via a PAGECACHE_TAG_DIRTY walk. + * The ->writepage implementation will run either folio_start_writeback() + * or folio_mark_dirty(), at which stage we bring the folio's dirty flag + * and xarray dirty tag back into sync. + * + * This incoherency between the folio's dirty flag and xarray tag is + * unfortunate, but it only exists while the folio is locked. */ -int clear_page_dirty_for_io(struct page *page) +bool folio_clear_dirty_for_io(struct folio *folio) { - struct address_space *mapping = page_mapping(page); - int ret = 0; + struct address_space *mapping = folio_mapping(folio); + bool ret = false; - BUG_ON(!PageLocked(page)); + VM_BUG_ON_FOLIO(!folio_test_locked(folio), folio); - if (mapping && mapping_cap_account_dirty(mapping)) { + if (mapping && mapping_can_writeback(mapping)) { struct inode *inode = mapping->host; struct bdi_writeback *wb; struct wb_lock_cookie cookie = {}; @@ -2668,73 +2842,97 @@ int clear_page_dirty_for_io(struct page *page) * We use this sequence to make sure that * (a) we account for dirty stats properly * (b) we tell the low-level filesystem to - * mark the whole page dirty if it was + * mark the whole folio dirty if it was * dirty in a pagetable. Only to then - * (c) clean the page again and return 1 to + * (c) clean the folio again and return 1 to * cause the writeback. * * This way we avoid all nasty races with the * dirty bit in multiple places and clearing * them concurrently from different threads. * - * Note! Normally the "set_page_dirty(page)" + * Note! Normally the "folio_mark_dirty(folio)" * has no effect on the actual dirty bit - since * that will already usually be set. But we * need the side effects, and it can help us * avoid races. * - * We basically use the page "master dirty bit" + * We basically use the folio "master dirty bit" * as a serialization point for all the different * threads doing their things. */ - if (page_mkclean(page)) - set_page_dirty(page); + if (folio_mkclean(folio)) + folio_mark_dirty(folio); /* * We carefully synchronise fault handlers against - * installing a dirty pte and marking the page dirty + * installing a dirty pte and marking the folio dirty * at this point. We do this by having them hold the - * page lock while dirtying the page, and pages are + * page lock while dirtying the folio, and folios are * always locked coming in here, so we get the desired * exclusion. */ wb = unlocked_inode_to_wb_begin(inode, &cookie); - if (TestClearPageDirty(page)) { - dec_lruvec_page_state(page, NR_FILE_DIRTY); - dec_zone_page_state(page, NR_ZONE_WRITE_PENDING); - dec_wb_stat(wb, WB_RECLAIMABLE); - ret = 1; + if (folio_test_clear_dirty(folio)) { + long nr = folio_nr_pages(folio); + lruvec_stat_mod_folio(folio, NR_FILE_DIRTY, -nr); + zone_stat_mod_folio(folio, NR_ZONE_WRITE_PENDING, -nr); + wb_stat_mod(wb, WB_RECLAIMABLE, -nr); + ret = true; } unlocked_inode_to_wb_end(inode, &cookie); return ret; } - return TestClearPageDirty(page); + return folio_test_clear_dirty(folio); } -EXPORT_SYMBOL(clear_page_dirty_for_io); +EXPORT_SYMBOL(folio_clear_dirty_for_io); -int test_clear_page_writeback(struct page *page) +static void wb_inode_writeback_start(struct bdi_writeback *wb) { - struct address_space *mapping = page_mapping(page); - struct mem_cgroup *memcg; - struct lruvec *lruvec; - int ret; + atomic_inc(&wb->writeback_inodes); +} + +static void wb_inode_writeback_end(struct bdi_writeback *wb) +{ + unsigned long flags; + atomic_dec(&wb->writeback_inodes); + /* + * Make sure estimate of writeback throughput gets updated after + * writeback completed. We delay the update by BANDWIDTH_INTERVAL + * (which is the interval other bandwidth updates use for batching) so + * that if multiple inodes end writeback at a similar time, they get + * batched into one bandwidth update. + */ + spin_lock_irqsave(&wb->work_lock, flags); + if (test_bit(WB_registered, &wb->state)) + queue_delayed_work(bdi_wq, &wb->bw_dwork, BANDWIDTH_INTERVAL); + spin_unlock_irqrestore(&wb->work_lock, flags); +} - memcg = lock_page_memcg(page); - lruvec = mem_cgroup_page_lruvec(page, page_pgdat(page)); +bool __folio_end_writeback(struct folio *folio) +{ + long nr = folio_nr_pages(folio); + struct address_space *mapping = folio_mapping(folio); + bool ret; + + folio_memcg_lock(folio); if (mapping && mapping_use_writeback_tags(mapping)) { struct inode *inode = mapping->host; struct backing_dev_info *bdi = inode_to_bdi(inode); unsigned long flags; xa_lock_irqsave(&mapping->i_pages, flags); - ret = TestClearPageWriteback(page); + ret = folio_test_clear_writeback(folio); if (ret) { - __xa_clear_mark(&mapping->i_pages, page_index(page), + __xa_clear_mark(&mapping->i_pages, folio_index(folio), PAGECACHE_TAG_WRITEBACK); - if (bdi_cap_account_writeback(bdi)) { + if (bdi->capabilities & BDI_CAP_WRITEBACK_ACCT) { struct bdi_writeback *wb = inode_to_wb(inode); - dec_wb_stat(wb, WB_WRITEBACK); - __wb_writeout_inc(wb); + wb_stat_mod(wb, WB_WRITEBACK, -nr); + __wb_writeout_add(wb, nr); + if (!mapping_tagged(mapping, + PAGECACHE_TAG_WRITEBACK)) + wb_inode_writeback_end(wb); } } @@ -2744,38 +2942,34 @@ int test_clear_page_writeback(struct page *page) xa_unlock_irqrestore(&mapping->i_pages, flags); } else { - ret = TestClearPageWriteback(page); + ret = folio_test_clear_writeback(folio); } - /* - * NOTE: Page might be free now! Writeback doesn't hold a page - * reference on its own, it relies on truncation to wait for - * the clearing of PG_writeback. The below can only access - * page state that is static across allocation cycles. - */ if (ret) { - dec_lruvec_state(lruvec, NR_WRITEBACK); - dec_zone_page_state(page, NR_ZONE_WRITE_PENDING); - inc_node_page_state(page, NR_WRITTEN); + lruvec_stat_mod_folio(folio, NR_WRITEBACK, -nr); + zone_stat_mod_folio(folio, NR_ZONE_WRITE_PENDING, -nr); + node_stat_mod_folio(folio, NR_WRITTEN, nr); } - __unlock_page_memcg(memcg); + folio_memcg_unlock(folio); return ret; } -int __test_set_page_writeback(struct page *page, bool keep_write) +bool __folio_start_writeback(struct folio *folio, bool keep_write) { - struct address_space *mapping = page_mapping(page); - int ret; + long nr = folio_nr_pages(folio); + struct address_space *mapping = folio_mapping(folio); + bool ret; + int access_ret; - lock_page_memcg(page); + folio_memcg_lock(folio); if (mapping && mapping_use_writeback_tags(mapping)) { - XA_STATE(xas, &mapping->i_pages, page_index(page)); + XA_STATE(xas, &mapping->i_pages, folio_index(folio)); struct inode *inode = mapping->host; struct backing_dev_info *bdi = inode_to_bdi(inode); unsigned long flags; xas_lock_irqsave(&xas, flags); xas_load(&xas); - ret = TestSetPageWriteback(page); + ret = folio_test_set_writeback(folio); if (!ret) { bool on_wblist; @@ -2783,58 +2977,108 @@ int __test_set_page_writeback(struct page *page, bool keep_write) PAGECACHE_TAG_WRITEBACK); xas_set_mark(&xas, PAGECACHE_TAG_WRITEBACK); - if (bdi_cap_account_writeback(bdi)) - inc_wb_stat(inode_to_wb(inode), WB_WRITEBACK); + if (bdi->capabilities & BDI_CAP_WRITEBACK_ACCT) { + struct bdi_writeback *wb = inode_to_wb(inode); + + wb_stat_mod(wb, WB_WRITEBACK, nr); + if (!on_wblist) + wb_inode_writeback_start(wb); + } /* - * We can come through here when swapping anonymous - * pages, so we don't necessarily have an inode to track - * for sync. + * We can come through here when swapping + * anonymous folios, so we don't necessarily + * have an inode to track for sync. */ if (mapping->host && !on_wblist) sb_mark_inode_writeback(mapping->host); } - if (!PageDirty(page)) + if (!folio_test_dirty(folio)) xas_clear_mark(&xas, PAGECACHE_TAG_DIRTY); if (!keep_write) xas_clear_mark(&xas, PAGECACHE_TAG_TOWRITE); xas_unlock_irqrestore(&xas, flags); } else { - ret = TestSetPageWriteback(page); + ret = folio_test_set_writeback(folio); } if (!ret) { - inc_lruvec_page_state(page, NR_WRITEBACK); - inc_zone_page_state(page, NR_ZONE_WRITE_PENDING); + lruvec_stat_mod_folio(folio, NR_WRITEBACK, nr); + zone_stat_mod_folio(folio, NR_ZONE_WRITE_PENDING, nr); } - unlock_page_memcg(page); + folio_memcg_unlock(folio); + access_ret = arch_make_folio_accessible(folio); + /* + * If writeback has been triggered on a page that cannot be made + * accessible, it is too late to recover here. + */ + VM_BUG_ON_FOLIO(access_ret != 0, folio); + return ret; +} +EXPORT_SYMBOL(__folio_start_writeback); +/** + * folio_wait_writeback - Wait for a folio to finish writeback. + * @folio: The folio to wait for. + * + * If the folio is currently being written back to storage, wait for the + * I/O to complete. + * + * Context: Sleeps. Must be called in process context and with + * no spinlocks held. Caller should hold a reference on the folio. + * If the folio is not locked, writeback may start again after writeback + * has finished. + */ +void folio_wait_writeback(struct folio *folio) +{ + while (folio_test_writeback(folio)) { + trace_folio_wait_writeback(folio, folio_mapping(folio)); + folio_wait_bit(folio, PG_writeback); + } } -EXPORT_SYMBOL(__test_set_page_writeback); +EXPORT_SYMBOL_GPL(folio_wait_writeback); -/* - * Wait for a page to complete writeback +/** + * folio_wait_writeback_killable - Wait for a folio to finish writeback. + * @folio: The folio to wait for. + * + * If the folio is currently being written back to storage, wait for the + * I/O to complete or a fatal signal to arrive. + * + * Context: Sleeps. Must be called in process context and with + * no spinlocks held. Caller should hold a reference on the folio. + * If the folio is not locked, writeback may start again after writeback + * has finished. + * Return: 0 on success, -EINTR if we get a fatal signal while waiting. */ -void wait_on_page_writeback(struct page *page) +int folio_wait_writeback_killable(struct folio *folio) { - if (PageWriteback(page)) { - trace_wait_on_page_writeback(page, page_mapping(page)); - wait_on_page_bit(page, PG_writeback); + while (folio_test_writeback(folio)) { + trace_folio_wait_writeback(folio, folio_mapping(folio)); + if (folio_wait_bit_killable(folio, PG_writeback)) + return -EINTR; } + + return 0; } -EXPORT_SYMBOL_GPL(wait_on_page_writeback); +EXPORT_SYMBOL_GPL(folio_wait_writeback_killable); /** - * wait_for_stable_page() - wait for writeback to finish, if necessary. - * @page: The page to wait on. + * folio_wait_stable() - wait for writeback to finish, if necessary. + * @folio: The folio to wait on. + * + * This function determines if the given folio is related to a backing + * device that requires folio contents to be held stable during writeback. + * If so, then it will wait for any pending writeback to complete. * - * This function determines if the given page is related to a backing device - * that requires page contents to be held stable during writeback. If so, then - * it will wait for any pending writeback to complete. + * Context: Sleeps. Must be called in process context and with + * no spinlocks held. Caller should hold a reference on the folio. + * If the folio is not locked, writeback may start again after writeback + * has finished. */ -void wait_for_stable_page(struct page *page) +void folio_wait_stable(struct folio *folio) { - if (bdi_cap_stable_pages_required(inode_to_bdi(page->mapping->host))) - wait_on_page_writeback(page); + if (folio_inode(folio)->i_sb->s_iflags & SB_I_STABLE_WRITES) + folio_wait_writeback(folio); } -EXPORT_SYMBOL_GPL(wait_for_stable_page); +EXPORT_SYMBOL_GPL(folio_wait_stable); |