#include <linux/backing-dev.h>
#include <linux/tracepoint.h>
#include <linux/device.h>
+#include <linux/memcontrol.h>
#include "internal.h"
/*
*/
#define MIN_WRITEBACK_PAGES (4096UL >> (PAGE_CACHE_SHIFT - 10))
+struct wb_completion {
+ atomic_t cnt;
+};
+
/*
* Passed into wb_writeback(), essentially a subset of writeback_control
*/
unsigned int range_cyclic:1;
unsigned int for_background:1;
unsigned int for_sync:1; /* sync(2) WB_SYNC_ALL writeback */
+ unsigned int auto_free:1; /* free on completion */
enum wb_reason reason; /* why was writeback initiated? */
struct list_head list; /* pending work list */
- struct completion *done; /* set if the caller waits */
+ struct wb_completion *done; /* set if the caller waits */
};
+/*
+ * If one wants to wait for one or more wb_writeback_works, each work's
+ * ->done should be set to a wb_completion defined using the following
+ * macro. Once all work items are issued with wb_queue_work(), the caller
+ * can wait for the completion of all using wb_wait_for_completion(). Work
+ * items which are waited upon aren't freed automatically on completion.
+ */
+#define DEFINE_WB_COMPLETION_ONSTACK(cmpl) \
+ struct wb_completion cmpl = { \
+ .cnt = ATOMIC_INIT(1), \
+ }
+
+
/*
* If an inode is constantly having its pages dirtied, but then the
* updates stop dirtytime_expire_interval seconds in the past, it's
*/
unsigned int dirtytime_expire_interval = 12 * 60 * 60;
+static inline struct inode *wb_inode(struct list_head *head)
+{
+ return list_entry(head, struct inode, i_io_list);
+}
+
+/*
+ * Include the creation of the trace points after defining the
+ * wb_writeback_work structure and inline functions so that the definition
+ * remains local to this file.
+ */
+#define CREATE_TRACE_POINTS
+#include <trace/events/writeback.h>
+
+EXPORT_TRACEPOINT_SYMBOL_GPL(wbc_writepage);
+
+static bool wb_io_lists_populated(struct bdi_writeback *wb)
+{
+ if (wb_has_dirty_io(wb)) {
+ return false;
+ } else {
+ set_bit(WB_has_dirty_io, &wb->state);
+ WARN_ON_ONCE(!wb->avg_write_bandwidth);
+ atomic_long_add(wb->avg_write_bandwidth,
+ &wb->bdi->tot_write_bandwidth);
+ return true;
+ }
+}
+
+static void wb_io_lists_depopulated(struct bdi_writeback *wb)
+{
+ if (wb_has_dirty_io(wb) && list_empty(&wb->b_dirty) &&
+ list_empty(&wb->b_io) && list_empty(&wb->b_more_io)) {
+ clear_bit(WB_has_dirty_io, &wb->state);
+ WARN_ON_ONCE(atomic_long_sub_return(wb->avg_write_bandwidth,
+ &wb->bdi->tot_write_bandwidth) < 0);
+ }
+}
+
/**
- * writeback_in_progress - determine whether there is writeback in progress
- * @bdi: the device's backing_dev_info structure.
+ * inode_io_list_move_locked - move an inode onto a bdi_writeback IO list
+ * @inode: inode to be moved
+ * @wb: target bdi_writeback
+ * @head: one of @wb->b_{dirty|io|more_io}
*
- * Determine whether there is writeback waiting to be handled against a
- * backing device.
+ * Move @inode->i_io_list to @list of @wb and set %WB_has_dirty_io.
+ * Returns %true if @inode is the first occupant of the !dirty_time IO
+ * lists; otherwise, %false.
*/
-int writeback_in_progress(struct backing_dev_info *bdi)
+static bool inode_io_list_move_locked(struct inode *inode,
+ struct bdi_writeback *wb,
+ struct list_head *head)
{
- return test_bit(BDI_writeback_running, &bdi->state);
+ assert_spin_locked(&wb->list_lock);
+
+ list_move(&inode->i_io_list, head);
+
+ /* dirty_time doesn't count as dirty_io until expiration */
+ if (head != &wb->b_dirty_time)
+ return wb_io_lists_populated(wb);
+
+ wb_io_lists_depopulated(wb);
+ return false;
}
-EXPORT_SYMBOL(writeback_in_progress);
-struct backing_dev_info *inode_to_bdi(struct inode *inode)
+/**
+ * inode_io_list_del_locked - remove an inode from its bdi_writeback IO list
+ * @inode: inode to be removed
+ * @wb: bdi_writeback @inode is being removed from
+ *
+ * Remove @inode which may be on one of @wb->b_{dirty|io|more_io} lists and
+ * clear %WB_has_dirty_io if all are empty afterwards.
+ */
+static void inode_io_list_del_locked(struct inode *inode,
+ struct bdi_writeback *wb)
{
- struct super_block *sb;
+ assert_spin_locked(&wb->list_lock);
- if (!inode)
- return &noop_backing_dev_info;
+ list_del_init(&inode->i_io_list);
+ wb_io_lists_depopulated(wb);
+}
- sb = inode->i_sb;
-#ifdef CONFIG_BLOCK
- if (sb_is_blkdev_sb(sb))
- return blk_get_backing_dev_info(I_BDEV(inode));
-#endif
- return sb->s_bdi;
+static void wb_wakeup(struct bdi_writeback *wb)
+{
+ spin_lock_bh(&wb->work_lock);
+ if (test_bit(WB_registered, &wb->state))
+ mod_delayed_work(bdi_wq, &wb->dwork, 0);
+ spin_unlock_bh(&wb->work_lock);
}
-EXPORT_SYMBOL_GPL(inode_to_bdi);
-static inline struct inode *wb_inode(struct list_head *head)
+static void wb_queue_work(struct bdi_writeback *wb,
+ struct wb_writeback_work *work)
{
- return list_entry(head, struct inode, i_wb_list);
+ trace_writeback_queue(wb, work);
+
+ spin_lock_bh(&wb->work_lock);
+ if (!test_bit(WB_registered, &wb->state))
+ goto out_unlock;
+ if (work->done)
+ atomic_inc(&work->done->cnt);
+ list_add_tail(&work->list, &wb->work_list);
+ mod_delayed_work(bdi_wq, &wb->dwork, 0);
+out_unlock:
+ spin_unlock_bh(&wb->work_lock);
}
-/*
- * Include the creation of the trace points after defining the
- * wb_writeback_work structure and inline functions so that the definition
- * remains local to this file.
+/**
+ * wb_wait_for_completion - wait for completion of bdi_writeback_works
+ * @bdi: bdi work items were issued to
+ * @done: target wb_completion
+ *
+ * Wait for one or more work items issued to @bdi with their ->done field
+ * set to @done, which should have been defined with
+ * DEFINE_WB_COMPLETION_ONSTACK(). This function returns after all such
+ * work items are completed. Work items which are waited upon aren't freed
+ * automatically on completion.
*/
-#define CREATE_TRACE_POINTS
-#include <trace/events/writeback.h>
+static void wb_wait_for_completion(struct backing_dev_info *bdi,
+ struct wb_completion *done)
+{
+ atomic_dec(&done->cnt); /* put down the initial count */
+ wait_event(bdi->wb_waitq, !atomic_read(&done->cnt));
+}
-EXPORT_TRACEPOINT_SYMBOL_GPL(wbc_writepage);
+#ifdef CONFIG_CGROUP_WRITEBACK
+
+/* parameters for foreign inode detection, see wb_detach_inode() */
+#define WB_FRN_TIME_SHIFT 13 /* 1s = 2^13, upto 8 secs w/ 16bit */
+#define WB_FRN_TIME_AVG_SHIFT 3 /* avg = avg * 7/8 + new * 1/8 */
+#define WB_FRN_TIME_CUT_DIV 2 /* ignore rounds < avg / 2 */
+#define WB_FRN_TIME_PERIOD (2 * (1 << WB_FRN_TIME_SHIFT)) /* 2s */
-static void bdi_wakeup_thread(struct backing_dev_info *bdi)
+#define WB_FRN_HIST_SLOTS 16 /* inode->i_wb_frn_history is 16bit */
+#define WB_FRN_HIST_UNIT (WB_FRN_TIME_PERIOD / WB_FRN_HIST_SLOTS)
+ /* each slot's duration is 2s / 16 */
+#define WB_FRN_HIST_THR_SLOTS (WB_FRN_HIST_SLOTS / 2)
+ /* if foreign slots >= 8, switch */
+#define WB_FRN_HIST_MAX_SLOTS (WB_FRN_HIST_THR_SLOTS / 2 + 1)
+ /* one round can affect upto 5 slots */
+
+static atomic_t isw_nr_in_flight = ATOMIC_INIT(0);
+static struct workqueue_struct *isw_wq;
+
+void __inode_attach_wb(struct inode *inode, struct page *page)
{
- spin_lock_bh(&bdi->wb_lock);
- if (test_bit(BDI_registered, &bdi->state))
- mod_delayed_work(bdi_wq, &bdi->wb.dwork, 0);
- spin_unlock_bh(&bdi->wb_lock);
+ struct backing_dev_info *bdi = inode_to_bdi(inode);
+ struct bdi_writeback *wb = NULL;
+
+ if (inode_cgwb_enabled(inode)) {
+ struct cgroup_subsys_state *memcg_css;
+
+ if (page) {
+ memcg_css = mem_cgroup_css_from_page(page);
+ wb = wb_get_create(bdi, memcg_css, GFP_ATOMIC);
+ } else {
+ /* must pin memcg_css, see wb_get_create() */
+ memcg_css = task_get_css(current, memory_cgrp_id);
+ wb = wb_get_create(bdi, memcg_css, GFP_ATOMIC);
+ css_put(memcg_css);
+ }
+ }
+
+ if (!wb)
+ wb = &bdi->wb;
+
+ /*
+ * There may be multiple instances of this function racing to
+ * update the same inode. Use cmpxchg() to tell the winner.
+ */
+ if (unlikely(cmpxchg(&inode->i_wb, NULL, wb)))
+ wb_put(wb);
}
-static void bdi_queue_work(struct backing_dev_info *bdi,
- struct wb_writeback_work *work)
+/**
+ * locked_inode_to_wb_and_lock_list - determine a locked inode's wb and lock it
+ * @inode: inode of interest with i_lock held
+ *
+ * Returns @inode's wb with its list_lock held. @inode->i_lock must be
+ * held on entry and is released on return. The returned wb is guaranteed
+ * to stay @inode's associated wb until its list_lock is released.
+ */
+static struct bdi_writeback *
+locked_inode_to_wb_and_lock_list(struct inode *inode)
+ __releases(&inode->i_lock)
+ __acquires(&wb->list_lock)
{
- trace_writeback_queue(bdi, work);
+ while (true) {
+ struct bdi_writeback *wb = inode_to_wb(inode);
- spin_lock_bh(&bdi->wb_lock);
- if (!test_bit(BDI_registered, &bdi->state)) {
- if (work->done)
- complete(work->done);
- goto out_unlock;
+ /*
+ * inode_to_wb() association is protected by both
+ * @inode->i_lock and @wb->list_lock but list_lock nests
+ * outside i_lock. Drop i_lock and verify that the
+ * association hasn't changed after acquiring list_lock.
+ */
+ wb_get(wb);
+ spin_unlock(&inode->i_lock);
+ spin_lock(&wb->list_lock);
+ wb_put(wb); /* not gonna deref it anymore */
+
+ /* i_wb may have changed inbetween, can't use inode_to_wb() */
+ if (likely(wb == inode->i_wb))
+ return wb; /* @inode already has ref */
+
+ spin_unlock(&wb->list_lock);
+ cpu_relax();
+ spin_lock(&inode->i_lock);
}
- list_add_tail(&work->list, &bdi->work_list);
- mod_delayed_work(bdi_wq, &bdi->wb.dwork, 0);
-out_unlock:
- spin_unlock_bh(&bdi->wb_lock);
}
-static void
-__bdi_start_writeback(struct backing_dev_info *bdi, long nr_pages,
- bool range_cyclic, enum wb_reason reason)
+/**
+ * inode_to_wb_and_lock_list - determine an inode's wb and lock it
+ * @inode: inode of interest
+ *
+ * Same as locked_inode_to_wb_and_lock_list() but @inode->i_lock isn't held
+ * on entry.
+ */
+static struct bdi_writeback *inode_to_wb_and_lock_list(struct inode *inode)
+ __acquires(&wb->list_lock)
+{
+ spin_lock(&inode->i_lock);
+ return locked_inode_to_wb_and_lock_list(inode);
+}
+
+struct inode_switch_wbs_context {
+ struct inode *inode;
+ struct bdi_writeback *new_wb;
+
+ struct rcu_head rcu_head;
+ struct work_struct work;
+};
+
+static void inode_switch_wbs_work_fn(struct work_struct *work)
+{
+ struct inode_switch_wbs_context *isw =
+ container_of(work, struct inode_switch_wbs_context, work);
+ struct inode *inode = isw->inode;
+ struct address_space *mapping = inode->i_mapping;
+ struct bdi_writeback *old_wb = inode->i_wb;
+ struct bdi_writeback *new_wb = isw->new_wb;
+ struct radix_tree_iter iter;
+ bool switched = false;
+ void **slot;
+
+ /*
+ * By the time control reaches here, RCU grace period has passed
+ * since I_WB_SWITCH assertion and all wb stat update transactions
+ * between unlocked_inode_to_wb_begin/end() are guaranteed to be
+ * synchronizing against mapping->tree_lock.
+ *
+ * Grabbing old_wb->list_lock, inode->i_lock and mapping->tree_lock
+ * gives us exclusion against all wb related operations on @inode
+ * including IO list manipulations and stat updates.
+ */
+ if (old_wb < new_wb) {
+ spin_lock(&old_wb->list_lock);
+ spin_lock_nested(&new_wb->list_lock, SINGLE_DEPTH_NESTING);
+ } else {
+ spin_lock(&new_wb->list_lock);
+ spin_lock_nested(&old_wb->list_lock, SINGLE_DEPTH_NESTING);
+ }
+ spin_lock(&inode->i_lock);
+ spin_lock_irq(&mapping->tree_lock);
+
+ /*
+ * Once I_FREEING is visible under i_lock, the eviction path owns
+ * the inode and we shouldn't modify ->i_io_list.
+ */
+ if (unlikely(inode->i_state & I_FREEING))
+ goto skip_switch;
+
+ /*
+ * Count and transfer stats. Note that PAGECACHE_TAG_DIRTY points
+ * to possibly dirty pages while PAGECACHE_TAG_WRITEBACK points to
+ * pages actually under underwriteback.
+ */
+ radix_tree_for_each_tagged(slot, &mapping->page_tree, &iter, 0,
+ PAGECACHE_TAG_DIRTY) {
+ struct page *page = radix_tree_deref_slot_protected(slot,
+ &mapping->tree_lock);
+ if (likely(page) && PageDirty(page)) {
+ __dec_wb_stat(old_wb, WB_RECLAIMABLE);
+ __inc_wb_stat(new_wb, WB_RECLAIMABLE);
+ }
+ }
+
+ radix_tree_for_each_tagged(slot, &mapping->page_tree, &iter, 0,
+ PAGECACHE_TAG_WRITEBACK) {
+ struct page *page = radix_tree_deref_slot_protected(slot,
+ &mapping->tree_lock);
+ if (likely(page)) {
+ WARN_ON_ONCE(!PageWriteback(page));
+ __dec_wb_stat(old_wb, WB_WRITEBACK);
+ __inc_wb_stat(new_wb, WB_WRITEBACK);
+ }
+ }
+
+ wb_get(new_wb);
+
+ /*
+ * Transfer to @new_wb's IO list if necessary. The specific list
+ * @inode was on is ignored and the inode is put on ->b_dirty which
+ * is always correct including from ->b_dirty_time. The transfer
+ * preserves @inode->dirtied_when ordering.
+ */
+ if (!list_empty(&inode->i_io_list)) {
+ struct inode *pos;
+
+ inode_io_list_del_locked(inode, old_wb);
+ inode->i_wb = new_wb;
+ list_for_each_entry(pos, &new_wb->b_dirty, i_io_list)
+ if (time_after_eq(inode->dirtied_when,
+ pos->dirtied_when))
+ break;
+ inode_io_list_move_locked(inode, new_wb, pos->i_io_list.prev);
+ } else {
+ inode->i_wb = new_wb;
+ }
+
+ /* ->i_wb_frn updates may race wbc_detach_inode() but doesn't matter */
+ inode->i_wb_frn_winner = 0;
+ inode->i_wb_frn_avg_time = 0;
+ inode->i_wb_frn_history = 0;
+ switched = true;
+skip_switch:
+ /*
+ * Paired with load_acquire in unlocked_inode_to_wb_begin() and
+ * ensures that the new wb is visible if they see !I_WB_SWITCH.
+ */
+ smp_store_release(&inode->i_state, inode->i_state & ~I_WB_SWITCH);
+
+ spin_unlock_irq(&mapping->tree_lock);
+ spin_unlock(&inode->i_lock);
+ spin_unlock(&new_wb->list_lock);
+ spin_unlock(&old_wb->list_lock);
+
+ if (switched) {
+ wb_wakeup(new_wb);
+ wb_put(old_wb);
+ }
+ wb_put(new_wb);
+
+ iput(inode);
+ kfree(isw);
+
+ atomic_dec(&isw_nr_in_flight);
+}
+
+static void inode_switch_wbs_rcu_fn(struct rcu_head *rcu_head)
+{
+ struct inode_switch_wbs_context *isw = container_of(rcu_head,
+ struct inode_switch_wbs_context, rcu_head);
+
+ /* needs to grab bh-unsafe locks, bounce to work item */
+ INIT_WORK(&isw->work, inode_switch_wbs_work_fn);
+ queue_work(isw_wq, &isw->work);
+}
+
+/**
+ * inode_switch_wbs - change the wb association of an inode
+ * @inode: target inode
+ * @new_wb_id: ID of the new wb
+ *
+ * Switch @inode's wb association to the wb identified by @new_wb_id. The
+ * switching is performed asynchronously and may fail silently.
+ */
+static void inode_switch_wbs(struct inode *inode, int new_wb_id)
+{
+ struct backing_dev_info *bdi = inode_to_bdi(inode);
+ struct cgroup_subsys_state *memcg_css;
+ struct inode_switch_wbs_context *isw;
+
+ /* noop if seems to be already in progress */
+ if (inode->i_state & I_WB_SWITCH)
+ return;
+
+ isw = kzalloc(sizeof(*isw), GFP_ATOMIC);
+ if (!isw)
+ return;
+
+ /* find and pin the new wb */
+ rcu_read_lock();
+ memcg_css = css_from_id(new_wb_id, &memory_cgrp_subsys);
+ if (memcg_css)
+ isw->new_wb = wb_get_create(bdi, memcg_css, GFP_ATOMIC);
+ rcu_read_unlock();
+ if (!isw->new_wb)
+ goto out_free;
+
+ /* while holding I_WB_SWITCH, no one else can update the association */
+ spin_lock(&inode->i_lock);
+ if (!(inode->i_sb->s_flags & MS_ACTIVE) ||
+ inode->i_state & (I_WB_SWITCH | I_FREEING) ||
+ inode_to_wb(inode) == isw->new_wb) {
+ spin_unlock(&inode->i_lock);
+ goto out_free;
+ }
+ inode->i_state |= I_WB_SWITCH;
+ spin_unlock(&inode->i_lock);
+
+ ihold(inode);
+ isw->inode = inode;
+
+ atomic_inc(&isw_nr_in_flight);
+
+ /*
+ * In addition to synchronizing among switchers, I_WB_SWITCH tells
+ * the RCU protected stat update paths to grab the mapping's
+ * tree_lock so that stat transfer can synchronize against them.
+ * Let's continue after I_WB_SWITCH is guaranteed to be visible.
+ */
+ call_rcu(&isw->rcu_head, inode_switch_wbs_rcu_fn);
+ return;
+
+out_free:
+ if (isw->new_wb)
+ wb_put(isw->new_wb);
+ kfree(isw);
+}
+
+/**
+ * wbc_attach_and_unlock_inode - associate wbc with target inode and unlock it
+ * @wbc: writeback_control of interest
+ * @inode: target inode
+ *
+ * @inode is locked and about to be written back under the control of @wbc.
+ * Record @inode's writeback context into @wbc and unlock the i_lock. On
+ * writeback completion, wbc_detach_inode() should be called. This is used
+ * to track the cgroup writeback context.
+ */
+void wbc_attach_and_unlock_inode(struct writeback_control *wbc,
+ struct inode *inode)
+{
+ if (!inode_cgwb_enabled(inode)) {
+ spin_unlock(&inode->i_lock);
+ return;
+ }
+
+ wbc->wb = inode_to_wb(inode);
+ wbc->inode = inode;
+
+ wbc->wb_id = wbc->wb->memcg_css->id;
+ wbc->wb_lcand_id = inode->i_wb_frn_winner;
+ wbc->wb_tcand_id = 0;
+ wbc->wb_bytes = 0;
+ wbc->wb_lcand_bytes = 0;
+ wbc->wb_tcand_bytes = 0;
+
+ wb_get(wbc->wb);
+ spin_unlock(&inode->i_lock);
+
+ /*
+ * A dying wb indicates that the memcg-blkcg mapping has changed
+ * and a new wb is already serving the memcg. Switch immediately.
+ */
+ if (unlikely(wb_dying(wbc->wb)))
+ inode_switch_wbs(inode, wbc->wb_id);
+}
+
+/**
+ * wbc_detach_inode - disassociate wbc from inode and perform foreign detection
+ * @wbc: writeback_control of the just finished writeback
+ *
+ * To be called after a writeback attempt of an inode finishes and undoes
+ * wbc_attach_and_unlock_inode(). Can be called under any context.
+ *
+ * As concurrent write sharing of an inode is expected to be very rare and
+ * memcg only tracks page ownership on first-use basis severely confining
+ * the usefulness of such sharing, cgroup writeback tracks ownership
+ * per-inode. While the support for concurrent write sharing of an inode
+ * is deemed unnecessary, an inode being written to by different cgroups at
+ * different points in time is a lot more common, and, more importantly,
+ * charging only by first-use can too readily lead to grossly incorrect
+ * behaviors (single foreign page can lead to gigabytes of writeback to be
+ * incorrectly attributed).
+ *
+ * To resolve this issue, cgroup writeback detects the majority dirtier of
+ * an inode and transfers the ownership to it. To avoid unnnecessary
+ * oscillation, the detection mechanism keeps track of history and gives
+ * out the switch verdict only if the foreign usage pattern is stable over
+ * a certain amount of time and/or writeback attempts.
+ *
+ * On each writeback attempt, @wbc tries to detect the majority writer
+ * using Boyer-Moore majority vote algorithm. In addition to the byte
+ * count from the majority voting, it also counts the bytes written for the
+ * current wb and the last round's winner wb (max of last round's current
+ * wb, the winner from two rounds ago, and the last round's majority
+ * candidate). Keeping track of the historical winner helps the algorithm
+ * to semi-reliably detect the most active writer even when it's not the
+ * absolute majority.
+ *
+ * Once the winner of the round is determined, whether the winner is
+ * foreign or not and how much IO time the round consumed is recorded in
+ * inode->i_wb_frn_history. If the amount of recorded foreign IO time is
+ * over a certain threshold, the switch verdict is given.
+ */
+void wbc_detach_inode(struct writeback_control *wbc)
+{
+ struct bdi_writeback *wb = wbc->wb;
+ struct inode *inode = wbc->inode;
+ unsigned long avg_time, max_bytes, max_time;
+ u16 history;
+ int max_id;
+
+ if (!wb)
+ return;
+
+ history = inode->i_wb_frn_history;
+ avg_time = inode->i_wb_frn_avg_time;
+
+ /* pick the winner of this round */
+ if (wbc->wb_bytes >= wbc->wb_lcand_bytes &&
+ wbc->wb_bytes >= wbc->wb_tcand_bytes) {
+ max_id = wbc->wb_id;
+ max_bytes = wbc->wb_bytes;
+ } else if (wbc->wb_lcand_bytes >= wbc->wb_tcand_bytes) {
+ max_id = wbc->wb_lcand_id;
+ max_bytes = wbc->wb_lcand_bytes;
+ } else {
+ max_id = wbc->wb_tcand_id;
+ max_bytes = wbc->wb_tcand_bytes;
+ }
+
+ /*
+ * Calculate the amount of IO time the winner consumed and fold it
+ * into the running average kept per inode. If the consumed IO
+ * time is lower than avag / WB_FRN_TIME_CUT_DIV, ignore it for
+ * deciding whether to switch or not. This is to prevent one-off
+ * small dirtiers from skewing the verdict.
+ */
+ max_time = DIV_ROUND_UP((max_bytes >> PAGE_SHIFT) << WB_FRN_TIME_SHIFT,
+ wb->avg_write_bandwidth);
+ if (avg_time)
+ avg_time += (max_time >> WB_FRN_TIME_AVG_SHIFT) -
+ (avg_time >> WB_FRN_TIME_AVG_SHIFT);
+ else
+ avg_time = max_time; /* immediate catch up on first run */
+
+ if (max_time >= avg_time / WB_FRN_TIME_CUT_DIV) {
+ int slots;
+
+ /*
+ * The switch verdict is reached if foreign wb's consume
+ * more than a certain proportion of IO time in a
+ * WB_FRN_TIME_PERIOD. This is loosely tracked by 16 slot
+ * history mask where each bit represents one sixteenth of
+ * the period. Determine the number of slots to shift into
+ * history from @max_time.
+ */
+ slots = min(DIV_ROUND_UP(max_time, WB_FRN_HIST_UNIT),
+ (unsigned long)WB_FRN_HIST_MAX_SLOTS);
+ history <<= slots;
+ if (wbc->wb_id != max_id)
+ history |= (1U << slots) - 1;
+
+ /*
+ * Switch if the current wb isn't the consistent winner.
+ * If there are multiple closely competing dirtiers, the
+ * inode may switch across them repeatedly over time, which
+ * is okay. The main goal is avoiding keeping an inode on
+ * the wrong wb for an extended period of time.
+ */
+ if (hweight32(history) > WB_FRN_HIST_THR_SLOTS)
+ inode_switch_wbs(inode, max_id);
+ }
+
+ /*
+ * Multiple instances of this function may race to update the
+ * following fields but we don't mind occassional inaccuracies.
+ */
+ inode->i_wb_frn_winner = max_id;
+ inode->i_wb_frn_avg_time = min(avg_time, (unsigned long)U16_MAX);
+ inode->i_wb_frn_history = history;
+
+ wb_put(wbc->wb);
+ wbc->wb = NULL;
+}
+
+/**
+ * wbc_account_io - account IO issued during writeback
+ * @wbc: writeback_control of the writeback in progress
+ * @page: page being written out
+ * @bytes: number of bytes being written out
+ *
+ * @bytes from @page are about to written out during the writeback
+ * controlled by @wbc. Keep the book for foreign inode detection. See
+ * wbc_detach_inode().
+ */
+void wbc_account_io(struct writeback_control *wbc, struct page *page,
+ size_t bytes)
+{
+ int id;
+
+ /*
+ * pageout() path doesn't attach @wbc to the inode being written
+ * out. This is intentional as we don't want the function to block
+ * behind a slow cgroup. Ultimately, we want pageout() to kick off
+ * regular writeback instead of writing things out itself.
+ */
+ if (!wbc->wb)
+ return;
+
+ rcu_read_lock();
+ id = mem_cgroup_css_from_page(page)->id;
+ rcu_read_unlock();
+
+ if (id == wbc->wb_id) {
+ wbc->wb_bytes += bytes;
+ return;
+ }
+
+ if (id == wbc->wb_lcand_id)
+ wbc->wb_lcand_bytes += bytes;
+
+ /* Boyer-Moore majority vote algorithm */
+ if (!wbc->wb_tcand_bytes)
+ wbc->wb_tcand_id = id;
+ if (id == wbc->wb_tcand_id)
+ wbc->wb_tcand_bytes += bytes;
+ else
+ wbc->wb_tcand_bytes -= min(bytes, wbc->wb_tcand_bytes);
+}
+EXPORT_SYMBOL_GPL(wbc_account_io);
+
+/**
+ * inode_congested - test whether an inode is congested
+ * @inode: inode to test for congestion (may be NULL)
+ * @cong_bits: mask of WB_[a]sync_congested bits to test
+ *
+ * Tests whether @inode is congested. @cong_bits is the mask of congestion
+ * bits to test and the return value is the mask of set bits.
+ *
+ * If cgroup writeback is enabled for @inode, the congestion state is
+ * determined by whether the cgwb (cgroup bdi_writeback) for the blkcg
+ * associated with @inode is congested; otherwise, the root wb's congestion
+ * state is used.
+ *
+ * @inode is allowed to be NULL as this function is often called on
+ * mapping->host which is NULL for the swapper space.
+ */
+int inode_congested(struct inode *inode, int cong_bits)
+{
+ /*
+ * Once set, ->i_wb never becomes NULL while the inode is alive.
+ * Start transaction iff ->i_wb is visible.
+ */
+ if (inode && inode_to_wb_is_valid(inode)) {
+ struct bdi_writeback *wb;
+ bool locked, congested;
+
+ wb = unlocked_inode_to_wb_begin(inode, &locked);
+ congested = wb_congested(wb, cong_bits);
+ unlocked_inode_to_wb_end(inode, locked);
+ return congested;
+ }
+
+ return wb_congested(&inode_to_bdi(inode)->wb, cong_bits);
+}
+EXPORT_SYMBOL_GPL(inode_congested);
+
+/**
+ * wb_split_bdi_pages - split nr_pages to write according to bandwidth
+ * @wb: target bdi_writeback to split @nr_pages to
+ * @nr_pages: number of pages to write for the whole bdi
+ *
+ * Split @wb's portion of @nr_pages according to @wb's write bandwidth in
+ * relation to the total write bandwidth of all wb's w/ dirty inodes on
+ * @wb->bdi.
+ */
+static long wb_split_bdi_pages(struct bdi_writeback *wb, long nr_pages)
+{
+ unsigned long this_bw = wb->avg_write_bandwidth;
+ unsigned long tot_bw = atomic_long_read(&wb->bdi->tot_write_bandwidth);
+
+ if (nr_pages == LONG_MAX)
+ return LONG_MAX;
+
+ /*
+ * This may be called on clean wb's and proportional distribution
+ * may not make sense, just use the original @nr_pages in those
+ * cases. In general, we wanna err on the side of writing more.
+ */
+ if (!tot_bw || this_bw >= tot_bw)
+ return nr_pages;
+ else
+ return DIV_ROUND_UP_ULL((u64)nr_pages * this_bw, tot_bw);
+}
+
+/**
+ * bdi_split_work_to_wbs - split a wb_writeback_work to all wb's of a bdi
+ * @bdi: target backing_dev_info
+ * @base_work: wb_writeback_work to issue
+ * @skip_if_busy: skip wb's which already have writeback in progress
+ *
+ * Split and issue @base_work to all wb's (bdi_writeback's) of @bdi which
+ * have dirty inodes. If @base_work->nr_page isn't %LONG_MAX, it's
+ * distributed to the busy wbs according to each wb's proportion in the
+ * total active write bandwidth of @bdi.
+ */
+static void bdi_split_work_to_wbs(struct backing_dev_info *bdi,
+ struct wb_writeback_work *base_work,
+ bool skip_if_busy)
+{
+ struct bdi_writeback *last_wb = NULL;
+ struct bdi_writeback *wb = list_entry(&bdi->wb_list,
+ struct bdi_writeback, bdi_node);
+
+ might_sleep();
+restart:
+ rcu_read_lock();
+ list_for_each_entry_continue_rcu(wb, &bdi->wb_list, bdi_node) {
+ DEFINE_WB_COMPLETION_ONSTACK(fallback_work_done);
+ struct wb_writeback_work fallback_work;
+ struct wb_writeback_work *work;
+ long nr_pages;
+
+ if (last_wb) {
+ wb_put(last_wb);
+ last_wb = NULL;
+ }
+
+ /* SYNC_ALL writes out I_DIRTY_TIME too */
+ if (!wb_has_dirty_io(wb) &&
+ (base_work->sync_mode == WB_SYNC_NONE ||
+ list_empty(&wb->b_dirty_time)))
+ continue;
+ if (skip_if_busy && writeback_in_progress(wb))
+ continue;
+
+ nr_pages = wb_split_bdi_pages(wb, base_work->nr_pages);
+
+ work = kmalloc(sizeof(*work), GFP_ATOMIC);
+ if (work) {
+ *work = *base_work;
+ work->nr_pages = nr_pages;
+ work->auto_free = 1;
+ wb_queue_work(wb, work);
+ continue;
+ }
+
+ /* alloc failed, execute synchronously using on-stack fallback */
+ work = &fallback_work;
+ *work = *base_work;
+ work->nr_pages = nr_pages;
+ work->auto_free = 0;
+ work->done = &fallback_work_done;
+
+ wb_queue_work(wb, work);
+
+ /*
+ * Pin @wb so that it stays on @bdi->wb_list. This allows
+ * continuing iteration from @wb after dropping and
+ * regrabbing rcu read lock.
+ */
+ wb_get(wb);
+ last_wb = wb;
+
+ rcu_read_unlock();
+ wb_wait_for_completion(bdi, &fallback_work_done);
+ goto restart;
+ }
+ rcu_read_unlock();
+
+ if (last_wb)
+ wb_put(last_wb);
+}
+
+/**
+ * cgroup_writeback_umount - flush inode wb switches for umount
+ *
+ * This function is called when a super_block is about to be destroyed and
+ * flushes in-flight inode wb switches. An inode wb switch goes through
+ * RCU and then workqueue, so the two need to be flushed in order to ensure
+ * that all previously scheduled switches are finished. As wb switches are
+ * rare occurrences and synchronize_rcu() can take a while, perform
+ * flushing iff wb switches are in flight.
+ */
+void cgroup_writeback_umount(void)
+{
+ if (atomic_read(&isw_nr_in_flight)) {
+ synchronize_rcu();
+ flush_workqueue(isw_wq);
+ }
+}
+
+static int __init cgroup_writeback_init(void)
+{
+ isw_wq = alloc_workqueue("inode_switch_wbs", 0, 0);
+ if (!isw_wq)
+ return -ENOMEM;
+ return 0;
+}
+fs_initcall(cgroup_writeback_init);
+
+#else /* CONFIG_CGROUP_WRITEBACK */
+
+static struct bdi_writeback *
+locked_inode_to_wb_and_lock_list(struct inode *inode)
+ __releases(&inode->i_lock)
+ __acquires(&wb->list_lock)
+{
+ struct bdi_writeback *wb = inode_to_wb(inode);
+
+ spin_unlock(&inode->i_lock);
+ spin_lock(&wb->list_lock);
+ return wb;
+}
+
+static struct bdi_writeback *inode_to_wb_and_lock_list(struct inode *inode)
+ __acquires(&wb->list_lock)
+{
+ struct bdi_writeback *wb = inode_to_wb(inode);
+
+ spin_lock(&wb->list_lock);
+ return wb;
+}
+
+static long wb_split_bdi_pages(struct bdi_writeback *wb, long nr_pages)
+{
+ return nr_pages;
+}
+
+static void bdi_split_work_to_wbs(struct backing_dev_info *bdi,
+ struct wb_writeback_work *base_work,
+ bool skip_if_busy)
+{
+ might_sleep();
+
+ if (!skip_if_busy || !writeback_in_progress(&bdi->wb)) {
+ base_work->auto_free = 0;
+ wb_queue_work(&bdi->wb, base_work);
+ }
+}
+
+#endif /* CONFIG_CGROUP_WRITEBACK */
+
+void wb_start_writeback(struct bdi_writeback *wb, long nr_pages,
+ bool range_cyclic, enum wb_reason reason)
{
struct wb_writeback_work *work;
+ if (!wb_has_dirty_io(wb))
+ return;
+
/*
* This is WB_SYNC_NONE writeback, so if allocation fails just
* wakeup the thread for old dirty data writeback
*/
work = kzalloc(sizeof(*work), GFP_ATOMIC);
if (!work) {
- trace_writeback_nowork(bdi);
- bdi_wakeup_thread(bdi);
+ trace_writeback_nowork(wb);
+ wb_wakeup(wb);
return;
}
work->nr_pages = nr_pages;
work->range_cyclic = range_cyclic;
work->reason = reason;
+ work->auto_free = 1;
- bdi_queue_work(bdi, work);
-}
-
-/**
- * bdi_start_writeback - start writeback
- * @bdi: the backing device to write from
- * @nr_pages: the number of pages to write
- * @reason: reason why some writeback work was initiated
- *
- * Description:
- * This does WB_SYNC_NONE opportunistic writeback. The IO is only
- * started when this function returns, we make no guarantees on
- * completion. Caller need not hold sb s_umount semaphore.
- *
- */
-void bdi_start_writeback(struct backing_dev_info *bdi, long nr_pages,
- enum wb_reason reason)
-{
- __bdi_start_writeback(bdi, nr_pages, true, reason);
+ wb_queue_work(wb, work);
}
/**
- * bdi_start_background_writeback - start background writeback
- * @bdi: the backing device to write from
+ * wb_start_background_writeback - start background writeback
+ * @wb: bdi_writback to write from
*
* Description:
* This makes sure WB_SYNC_NONE background writeback happens. When
- * this function returns, it is only guaranteed that for given BDI
+ * this function returns, it is only guaranteed that for given wb
* some IO is happening if we are over background dirty threshold.
* Caller need not hold sb s_umount semaphore.
*/
-void bdi_start_background_writeback(struct backing_dev_info *bdi)
+void wb_start_background_writeback(struct bdi_writeback *wb)
{
/*
* We just wake up the flusher thread. It will perform background
* writeback as soon as there is no other work to do.
*/
- trace_writeback_wake_background(bdi);
- bdi_wakeup_thread(bdi);
+ trace_writeback_wake_background(wb);
+ wb_wakeup(wb);
}
/*
* Remove the inode from the writeback list it is on.
*/
-void inode_wb_list_del(struct inode *inode)
+void inode_io_list_del(struct inode *inode)
{
- struct backing_dev_info *bdi = inode_to_bdi(inode);
+ struct bdi_writeback *wb;
- spin_lock(&bdi->wb.list_lock);
- list_del_init(&inode->i_wb_list);
- spin_unlock(&bdi->wb.list_lock);
+ wb = inode_to_wb_and_lock_list(inode);
+ inode_io_list_del_locked(inode, wb);
+ spin_unlock(&wb->list_lock);
}
/*
*/
static void redirty_tail(struct inode *inode, struct bdi_writeback *wb)
{
- assert_spin_locked(&wb->list_lock);
if (!list_empty(&wb->b_dirty)) {
struct inode *tail;
if (time_before(inode->dirtied_when, tail->dirtied_when))
inode->dirtied_when = jiffies;
}
- list_move(&inode->i_wb_list, &wb->b_dirty);
+ inode_io_list_move_locked(inode, wb, &wb->b_dirty);
}
/*
*/
static void requeue_io(struct inode *inode, struct bdi_writeback *wb)
{
- assert_spin_locked(&wb->list_lock);
- list_move(&inode->i_wb_list, &wb->b_more_io);
+ inode_io_list_move_locked(inode, wb, &wb->b_more_io);
}
static void inode_sync_complete(struct inode *inode)
if (older_than_this &&
inode_dirtied_after(inode, *older_than_this))
break;
- list_move(&inode->i_wb_list, &tmp);
+ list_move(&inode->i_io_list, &tmp);
moved++;
if (flags & EXPIRE_DIRTY_ATIME)
set_bit(__I_DIRTY_TIME_EXPIRED, &inode->i_state);
list_for_each_prev_safe(pos, node, &tmp) {
inode = wb_inode(pos);
if (inode->i_sb == sb)
- list_move(&inode->i_wb_list, dispatch_queue);
+ list_move(&inode->i_io_list, dispatch_queue);
}
}
out:
moved = move_expired_inodes(&wb->b_dirty, &wb->b_io, 0, work);
moved += move_expired_inodes(&wb->b_dirty_time, &wb->b_io,
EXPIRE_DIRTY_ATIME, work);
+ if (moved)
+ wb_io_lists_populated(wb);
trace_writeback_queue_io(wb, work, moved);
}
redirty_tail(inode, wb);
} else if (inode->i_state & I_DIRTY_TIME) {
inode->dirtied_when = jiffies;
- list_move(&inode->i_wb_list, &wb->b_dirty_time);
+ inode_io_list_move_locked(inode, wb, &wb->b_dirty_time);
} else {
/* The inode is clean. Remove from writeback lists. */
- list_del_init(&inode->i_wb_list);
+ inode_io_list_del_locked(inode, wb);
}
}
!mapping_tagged(inode->i_mapping, PAGECACHE_TAG_WRITEBACK)))
goto out;
inode->i_state |= I_SYNC;
- spin_unlock(&inode->i_lock);
+ wbc_attach_and_unlock_inode(wbc, inode);
ret = __writeback_single_inode(inode, wbc);
+ wbc_detach_inode(wbc);
spin_lock(&wb->list_lock);
spin_lock(&inode->i_lock);
/*
* touch it. See comment above for explanation.
*/
if (!(inode->i_state & I_DIRTY_ALL))
- list_del_init(&inode->i_wb_list);
+ inode_io_list_del_locked(inode, wb);
spin_unlock(&wb->list_lock);
inode_sync_complete(inode);
out:
return ret;
}
-static long writeback_chunk_size(struct backing_dev_info *bdi,
+static long writeback_chunk_size(struct bdi_writeback *wb,
struct wb_writeback_work *work)
{
long pages;
if (work->sync_mode == WB_SYNC_ALL || work->tagged_writepages)
pages = LONG_MAX;
else {
- pages = min(bdi->avg_write_bandwidth / 2,
- global_dirty_limit / DIRTY_SCOPE);
+ pages = min(wb->avg_write_bandwidth / 2,
+ global_wb_domain.dirty_limit / DIRTY_SCOPE);
pages = min(pages, work->nr_pages);
pages = round_down(pages + MIN_WRITEBACK_PAGES,
MIN_WRITEBACK_PAGES);
* Write a portion of b_io inodes which belong to @sb.
*
* Return the number of pages and/or inodes written.
+ *
+ * NOTE! This is called with wb->list_lock held, and will
+ * unlock and relock that for each inode it ends up doing
+ * IO for.
*/
static long writeback_sb_inodes(struct super_block *sb,
struct bdi_writeback *wb,
continue;
}
inode->i_state |= I_SYNC;
- spin_unlock(&inode->i_lock);
+ wbc_attach_and_unlock_inode(&wbc, inode);
- write_chunk = writeback_chunk_size(wb->bdi, work);
+ write_chunk = writeback_chunk_size(wb, work);
wbc.nr_to_write = write_chunk;
wbc.pages_skipped = 0;
*/
__writeback_single_inode(inode, &wbc);
+ wbc_detach_inode(&wbc);
work->nr_pages -= write_chunk - wbc.nr_to_write;
wrote += write_chunk - wbc.nr_to_write;
+
+ if (need_resched()) {
+ /*
+ * We're trying to balance between building up a nice
+ * long list of IOs to improve our merge rate, and
+ * getting those IOs out quickly for anyone throttling
+ * in balance_dirty_pages(). cond_resched() doesn't
+ * unplug, so get our IOs out the door before we
+ * give up the CPU.
+ */
+ blk_flush_plug(current);
+ cond_resched();
+ }
+
+
spin_lock(&wb->list_lock);
spin_lock(&inode->i_lock);
if (!(inode->i_state & I_DIRTY_ALL))
requeue_inode(inode, wb, &wbc);
inode_sync_complete(inode);
spin_unlock(&inode->i_lock);
- cond_resched_lock(&wb->list_lock);
+
/*
* bail out to wb_writeback() often enough to check
* background threshold and other termination conditions.
.range_cyclic = 1,
.reason = reason,
};
+ struct blk_plug plug;
+ blk_start_plug(&plug);
spin_lock(&wb->list_lock);
if (list_empty(&wb->b_io))
queue_io(wb, &work);
__writeback_inodes_wb(wb, &work);
spin_unlock(&wb->list_lock);
+ blk_finish_plug(&plug);
return nr_pages - work.nr_pages;
}
-static bool over_bground_thresh(struct backing_dev_info *bdi)
-{
- unsigned long background_thresh, dirty_thresh;
-
- global_dirty_limits(&background_thresh, &dirty_thresh);
-
- if (global_page_state(NR_FILE_DIRTY) +
- global_page_state(NR_UNSTABLE_NFS) > background_thresh)
- return true;
-
- if (bdi_stat(bdi, BDI_RECLAIMABLE) >
- bdi_dirty_limit(bdi, background_thresh))
- return true;
-
- return false;
-}
-
-/*
- * Called under wb->list_lock. If there are multiple wb per bdi,
- * only the flusher working on the first wb should do it.
- */
-static void wb_update_bandwidth(struct bdi_writeback *wb,
- unsigned long start_time)
-{
- __bdi_update_bandwidth(wb->bdi, 0, 0, 0, 0, 0, start_time);
-}
-
/*
* Explicit flushing or periodic writeback of "old" data.
*
unsigned long oldest_jif;
struct inode *inode;
long progress;
+ struct blk_plug plug;
oldest_jif = jiffies;
work->older_than_this = &oldest_jif;
+ blk_start_plug(&plug);
spin_lock(&wb->list_lock);
for (;;) {
/*
* after the other works are all done.
*/
if ((work->for_background || work->for_kupdate) &&
- !list_empty(&wb->bdi->work_list))
+ !list_empty(&wb->work_list))
break;
/*
* For background writeout, stop when we are below the
* background dirty threshold
*/
- if (work->for_background && !over_bground_thresh(wb->bdi))
+ if (work->for_background && !wb_over_bg_thresh(wb))
break;
/*
} else if (work->for_background)
oldest_jif = jiffies;
- trace_writeback_start(wb->bdi, work);
+ trace_writeback_start(wb, work);
if (list_empty(&wb->b_io))
queue_io(wb, work);
if (work->sb)
progress = writeback_sb_inodes(work->sb, wb, work);
else
progress = __writeback_inodes_wb(wb, work);
- trace_writeback_written(wb->bdi, work);
+ trace_writeback_written(wb, work);
wb_update_bandwidth(wb, wb_start);
* we'll just busyloop.
*/
if (!list_empty(&wb->b_more_io)) {
- trace_writeback_wait(wb->bdi, work);
+ trace_writeback_wait(wb, work);
inode = wb_inode(wb->b_more_io.prev);
spin_lock(&inode->i_lock);
spin_unlock(&wb->list_lock);
}
}
spin_unlock(&wb->list_lock);
+ blk_finish_plug(&plug);
return nr_pages - work->nr_pages;
}
/*
* Return the next wb_writeback_work struct that hasn't been processed yet.
*/
-static struct wb_writeback_work *
-get_next_work_item(struct backing_dev_info *bdi)
+static struct wb_writeback_work *get_next_work_item(struct bdi_writeback *wb)
{
struct wb_writeback_work *work = NULL;
- spin_lock_bh(&bdi->wb_lock);
- if (!list_empty(&bdi->work_list)) {
- work = list_entry(bdi->work_list.next,
+ spin_lock_bh(&wb->work_lock);
+ if (!list_empty(&wb->work_list)) {
+ work = list_entry(wb->work_list.next,
struct wb_writeback_work, list);
list_del_init(&work->list);
}
- spin_unlock_bh(&bdi->wb_lock);
+ spin_unlock_bh(&wb->work_lock);
return work;
}
static long wb_check_background_flush(struct bdi_writeback *wb)
{
- if (over_bground_thresh(wb->bdi)) {
+ if (wb_over_bg_thresh(wb)) {
struct wb_writeback_work work = {
.nr_pages = LONG_MAX,
*/
static long wb_do_writeback(struct bdi_writeback *wb)
{
- struct backing_dev_info *bdi = wb->bdi;
struct wb_writeback_work *work;
long wrote = 0;
- set_bit(BDI_writeback_running, &wb->bdi->state);
- while ((work = get_next_work_item(bdi)) != NULL) {
+ set_bit(WB_writeback_running, &wb->state);
+ while ((work = get_next_work_item(wb)) != NULL) {
+ struct wb_completion *done = work->done;
- trace_writeback_exec(bdi, work);
+ trace_writeback_exec(wb, work);
wrote += wb_writeback(wb, work);
- /*
- * Notify the caller of completion if this is a synchronous
- * work item, otherwise just free it.
- */
- if (work->done)
- complete(work->done);
- else
+ if (work->auto_free)
kfree(work);
+ if (done && atomic_dec_and_test(&done->cnt))
+ wake_up_all(&wb->bdi->wb_waitq);
}
/*
*/
wrote += wb_check_old_data_flush(wb);
wrote += wb_check_background_flush(wb);
- clear_bit(BDI_writeback_running, &wb->bdi->state);
+ clear_bit(WB_writeback_running, &wb->state);
return wrote;
}
* Handle writeback of dirty data for the device backed by this bdi. Also
* reschedules periodically and does kupdated style flushing.
*/
-void bdi_writeback_workfn(struct work_struct *work)
+void wb_workfn(struct work_struct *work)
{
struct bdi_writeback *wb = container_of(to_delayed_work(work),
struct bdi_writeback, dwork);
- struct backing_dev_info *bdi = wb->bdi;
long pages_written;
- set_worker_desc("flush-%s", dev_name(bdi->dev));
+ set_worker_desc("flush-%s", dev_name(wb->bdi->dev));
current->flags |= PF_SWAPWRITE;
if (likely(!current_is_workqueue_rescuer() ||
- !test_bit(BDI_registered, &bdi->state))) {
+ !test_bit(WB_registered, &wb->state))) {
/*
- * The normal path. Keep writing back @bdi until its
+ * The normal path. Keep writing back @wb until its
* work_list is empty. Note that this path is also taken
- * if @bdi is shutting down even when we're running off the
+ * if @wb is shutting down even when we're running off the
* rescuer as work_list needs to be drained.
*/
do {
pages_written = wb_do_writeback(wb);
trace_writeback_pages_written(pages_written);
- } while (!list_empty(&bdi->work_list));
+ } while (!list_empty(&wb->work_list));
} else {
/*
* bdi_wq can't get enough workers and we're running off
* the emergency worker. Don't hog it. Hopefully, 1024 is
* enough for efficient IO.
*/
- pages_written = writeback_inodes_wb(&bdi->wb, 1024,
+ pages_written = writeback_inodes_wb(wb, 1024,
WB_REASON_FORKER_THREAD);
trace_writeback_pages_written(pages_written);
}
- if (!list_empty(&bdi->work_list))
+ if (!list_empty(&wb->work_list))
mod_delayed_work(bdi_wq, &wb->dwork, 0);
else if (wb_has_dirty_io(wb) && dirty_writeback_interval)
- bdi_wakeup_thread_delayed(bdi);
+ wb_wakeup_delayed(wb);
current->flags &= ~PF_SWAPWRITE;
}
rcu_read_lock();
list_for_each_entry_rcu(bdi, &bdi_list, bdi_list) {
+ struct bdi_writeback *wb;
+
if (!bdi_has_dirty_io(bdi))
continue;
- __bdi_start_writeback(bdi, nr_pages, false, reason);
+
+ list_for_each_entry_rcu(wb, &bdi->wb_list, bdi_node)
+ wb_start_writeback(wb, wb_split_bdi_pages(wb, nr_pages),
+ false, reason);
}
rcu_read_unlock();
}
rcu_read_lock();
list_for_each_entry_rcu(bdi, &bdi_list, bdi_list) {
- if (list_empty(&bdi->wb.b_dirty_time))
- continue;
- bdi_wakeup_thread(bdi);
+ struct bdi_writeback *wb;
+
+ list_for_each_entry_rcu(wb, &bdi->wb_list, bdi_node)
+ if (!list_empty(&wb->b_dirty_time))
+ wb_wakeup(wb);
}
rcu_read_unlock();
schedule_delayed_work(&dirtytime_work, dirtytime_expire_interval * HZ);
* page->mapping->host, so the page-dirtying time is recorded in the internal
* blockdev inode.
*/
-#define I_DIRTY_INODE (I_DIRTY_SYNC | I_DIRTY_DATASYNC)
void __mark_inode_dirty(struct inode *inode, int flags)
{
+#define I_DIRTY_INODE (I_DIRTY_SYNC | I_DIRTY_DATASYNC)
struct super_block *sb = inode->i_sb;
- struct backing_dev_info *bdi = NULL;
int dirtytime;
trace_writeback_mark_inode_dirty(inode, flags);
if ((inode->i_state & flags) != flags) {
const int was_dirty = inode->i_state & I_DIRTY;
+ inode_attach_wb(inode, NULL);
+
if (flags & I_DIRTY_INODE)
inode->i_state &= ~I_DIRTY_TIME;
inode->i_state |= flags;
* reposition it (that would break b_dirty time-ordering).
*/
if (!was_dirty) {
+ struct bdi_writeback *wb;
+ struct list_head *dirty_list;
bool wakeup_bdi = false;
- bdi = inode_to_bdi(inode);
- spin_unlock(&inode->i_lock);
- spin_lock(&bdi->wb.list_lock);
- if (bdi_cap_writeback_dirty(bdi)) {
- WARN(!test_bit(BDI_registered, &bdi->state),
- "bdi-%s not registered\n", bdi->name);
+ wb = locked_inode_to_wb_and_lock_list(inode);
- /*
- * If this is the first dirty inode for this
- * bdi, we have to wake-up the corresponding
- * bdi thread to make sure background
- * write-back happens later.
- */
- if (!wb_has_dirty_io(&bdi->wb))
- wakeup_bdi = true;
- }
+ WARN(bdi_cap_writeback_dirty(wb->bdi) &&
+ !test_bit(WB_registered, &wb->state),
+ "bdi-%s not registered\n", wb->bdi->name);
inode->dirtied_when = jiffies;
if (dirtytime)
inode->dirtied_time_when = jiffies;
+
if (inode->i_state & (I_DIRTY_INODE | I_DIRTY_PAGES))
- list_move(&inode->i_wb_list, &bdi->wb.b_dirty);
+ dirty_list = &wb->b_dirty;
else
- list_move(&inode->i_wb_list,
- &bdi->wb.b_dirty_time);
- spin_unlock(&bdi->wb.list_lock);
+ dirty_list = &wb->b_dirty_time;
+
+ wakeup_bdi = inode_io_list_move_locked(inode, wb,
+ dirty_list);
+
+ spin_unlock(&wb->list_lock);
trace_writeback_dirty_inode_enqueue(inode);
- if (wakeup_bdi)
- bdi_wakeup_thread_delayed(bdi);
+ /*
+ * If this is the first dirty inode for this bdi,
+ * we have to wake-up the corresponding bdi thread
+ * to make sure background write-back happens
+ * later.
+ */
+ if (bdi_cap_writeback_dirty(wb->bdi) && wakeup_bdi)
+ wb_wakeup_delayed(wb);
return;
}
}
out_unlock_inode:
spin_unlock(&inode->i_lock);
+#undef I_DIRTY_INODE
}
EXPORT_SYMBOL(__mark_inode_dirty);
+/*
+ * The @s_sync_lock is used to serialise concurrent sync operations
+ * to avoid lock contention problems with concurrent wait_sb_inodes() calls.
+ * Concurrent callers will block on the s_sync_lock rather than doing contending
+ * walks. The queueing maintains sync(2) required behaviour as all the IO that
+ * has been issued up to the time this function is enter is guaranteed to be
+ * completed by the time we have gained the lock and waited for all IO that is
+ * in progress regardless of the order callers are granted the lock.
+ */
static void wait_sb_inodes(struct super_block *sb)
{
struct inode *inode, *old_inode = NULL;
*/
WARN_ON(!rwsem_is_locked(&sb->s_umount));
- spin_lock(&inode_sb_list_lock);
+ mutex_lock(&sb->s_sync_lock);
+ spin_lock(&sb->s_inode_list_lock);
/*
* Data integrity sync. Must wait for all pages under writeback,
}
__iget(inode);
spin_unlock(&inode->i_lock);
- spin_unlock(&inode_sb_list_lock);
+ spin_unlock(&sb->s_inode_list_lock);
/*
* We hold a reference to 'inode' so it couldn't have been
* removed from s_inodes list while we dropped the
- * inode_sb_list_lock. We cannot iput the inode now as we can
+ * s_inode_list_lock. We cannot iput the inode now as we can
* be holding the last reference and we cannot iput it under
- * inode_sb_list_lock. So we keep the reference and iput it
+ * s_inode_list_lock. So we keep the reference and iput it
* later.
*/
iput(old_inode);
old_inode = inode;
- filemap_fdatawait(mapping);
+ /*
+ * We keep the error status of individual mapping so that
+ * applications can catch the writeback error using fsync(2).
+ * See filemap_fdatawait_keep_errors() for details.
+ */
+ filemap_fdatawait_keep_errors(mapping);
cond_resched();
- spin_lock(&inode_sb_list_lock);
+ spin_lock(&sb->s_inode_list_lock);
}
- spin_unlock(&inode_sb_list_lock);
+ spin_unlock(&sb->s_inode_list_lock);
iput(old_inode);
+ mutex_unlock(&sb->s_sync_lock);
+}
+
+static void __writeback_inodes_sb_nr(struct super_block *sb, unsigned long nr,
+ enum wb_reason reason, bool skip_if_busy)
+{
+ DEFINE_WB_COMPLETION_ONSTACK(done);
+ struct wb_writeback_work work = {
+ .sb = sb,
+ .sync_mode = WB_SYNC_NONE,
+ .tagged_writepages = 1,
+ .done = &done,
+ .nr_pages = nr,
+ .reason = reason,
+ };
+ struct backing_dev_info *bdi = sb->s_bdi;
+
+ if (!bdi_has_dirty_io(bdi) || bdi == &noop_backing_dev_info)
+ return;
+ WARN_ON(!rwsem_is_locked(&sb->s_umount));
+
+ bdi_split_work_to_wbs(sb->s_bdi, &work, skip_if_busy);
+ wb_wait_for_completion(bdi, &done);
}
/**
unsigned long nr,
enum wb_reason reason)
{
- DECLARE_COMPLETION_ONSTACK(done);
- struct wb_writeback_work work = {
- .sb = sb,
- .sync_mode = WB_SYNC_NONE,
- .tagged_writepages = 1,
- .done = &done,
- .nr_pages = nr,
- .reason = reason,
- };
-
- if (sb->s_bdi == &noop_backing_dev_info)
- return;
- WARN_ON(!rwsem_is_locked(&sb->s_umount));
- bdi_queue_work(sb->s_bdi, &work);
- wait_for_completion(&done);
+ __writeback_inodes_sb_nr(sb, nr, reason, false);
}
EXPORT_SYMBOL(writeback_inodes_sb_nr);
* Invoke writeback_inodes_sb_nr if no writeback is currently underway.
* Returns 1 if writeback was started, 0 if not.
*/
-int try_to_writeback_inodes_sb_nr(struct super_block *sb,
- unsigned long nr,
- enum wb_reason reason)
+bool try_to_writeback_inodes_sb_nr(struct super_block *sb, unsigned long nr,
+ enum wb_reason reason)
{
- if (writeback_in_progress(sb->s_bdi))
- return 1;
-
if (!down_read_trylock(&sb->s_umount))
- return 0;
+ return false;
- writeback_inodes_sb_nr(sb, nr, reason);
+ __writeback_inodes_sb_nr(sb, nr, reason, true);
up_read(&sb->s_umount);
- return 1;
+ return true;
}
EXPORT_SYMBOL(try_to_writeback_inodes_sb_nr);
* Implement by try_to_writeback_inodes_sb_nr()
* Returns 1 if writeback was started, 0 if not.
*/
-int try_to_writeback_inodes_sb(struct super_block *sb, enum wb_reason reason)
+bool try_to_writeback_inodes_sb(struct super_block *sb, enum wb_reason reason)
{
return try_to_writeback_inodes_sb_nr(sb, get_nr_dirty_pages(), reason);
}
*/
void sync_inodes_sb(struct super_block *sb)
{
- DECLARE_COMPLETION_ONSTACK(done);
+ DEFINE_WB_COMPLETION_ONSTACK(done);
struct wb_writeback_work work = {
.sb = sb,
.sync_mode = WB_SYNC_ALL,
.reason = WB_REASON_SYNC,
.for_sync = 1,
};
+ struct backing_dev_info *bdi = sb->s_bdi;
- /* Nothing to do? */
- if (sb->s_bdi == &noop_backing_dev_info)
+ /*
+ * Can't skip on !bdi_has_dirty() because we should wait for !dirty
+ * inodes under writeback and I_DIRTY_TIME inodes ignored by
+ * bdi_has_dirty() need to be written out too.
+ */
+ if (bdi == &noop_backing_dev_info)
return;
WARN_ON(!rwsem_is_locked(&sb->s_umount));
- bdi_queue_work(sb->s_bdi, &work);
- wait_for_completion(&done);
+ bdi_split_work_to_wbs(bdi, &work, false);
+ wb_wait_for_completion(bdi, &done);
wait_sb_inodes(sb);
}
Code Review / kvmfornfv.git / blobdiff