Commit 0e175a18 authored by Curt Wohlgemuth's avatar Curt Wohlgemuth Committed by Wu Fengguang

writeback: Add a 'reason' to wb_writeback_work

This creates a new 'reason' field in a wb_writeback_work
structure, which unambiguously identifies who initiates
writeback activity.  A 'wb_reason' enumeration has been
added to writeback.h, to enumerate the possible reasons.

The 'writeback_work_class' and tracepoint event class and
'writeback_queue_io' tracepoints are updated to include the
symbolic 'reason' in all trace events.

And the 'writeback_inodes_sbXXX' family of routines has had
a wb_stats parameter added to them, so callers can specify
why writeback is being started.
Acked-by: default avatarJan Kara <jack@suse.cz>
Signed-off-by: default avatarCurt Wohlgemuth <curtw@google.com>
Signed-off-by: default avatarWu Fengguang <fengguang.wu@intel.com>
parent ad4e38dd
......@@ -3340,7 +3340,8 @@ static int shrink_delalloc(struct btrfs_trans_handle *trans,
smp_mb();
nr_pages = min_t(unsigned long, nr_pages,
root->fs_info->delalloc_bytes >> PAGE_CACHE_SHIFT);
writeback_inodes_sb_nr_if_idle(root->fs_info->sb, nr_pages);
writeback_inodes_sb_nr_if_idle(root->fs_info->sb, nr_pages,
WB_REASON_FS_FREE_SPACE);
spin_lock(&space_info->lock);
if (reserved > space_info->bytes_reserved)
......
......@@ -285,7 +285,7 @@ static void free_more_memory(void)
struct zone *zone;
int nid;
wakeup_flusher_threads(1024);
wakeup_flusher_threads(1024, WB_REASON_FREE_MORE_MEM);
yield();
for_each_online_node(nid) {
......
......@@ -2241,7 +2241,7 @@ static int ext4_nonda_switch(struct super_block *sb)
* start pushing delalloc when 1/2 of free blocks are dirty.
*/
if (free_blocks < 2 * dirty_blocks)
writeback_inodes_sb_if_idle(sb);
writeback_inodes_sb_if_idle(sb, WB_REASON_FS_FREE_SPACE);
return 0;
}
......
......@@ -41,11 +41,23 @@ struct wb_writeback_work {
unsigned int for_kupdate:1;
unsigned int range_cyclic:1;
unsigned int for_background:1;
enum wb_reason reason; /* why was writeback initiated? */
struct list_head list; /* pending work list */
struct completion *done; /* set if the caller waits */
};
const char *wb_reason_name[] = {
[WB_REASON_BACKGROUND] = "background",
[WB_REASON_TRY_TO_FREE_PAGES] = "try_to_free_pages",
[WB_REASON_SYNC] = "sync",
[WB_REASON_PERIODIC] = "periodic",
[WB_REASON_LAPTOP_TIMER] = "laptop_timer",
[WB_REASON_FREE_MORE_MEM] = "free_more_memory",
[WB_REASON_FS_FREE_SPACE] = "fs_free_space",
[WB_REASON_FORKER_THREAD] = "forker_thread"
};
/*
* Include the creation of the trace points after defining the
* wb_writeback_work structure so that the definition remains local to this
......@@ -115,7 +127,7 @@ static void bdi_queue_work(struct backing_dev_info *bdi,
static void
__bdi_start_writeback(struct backing_dev_info *bdi, long nr_pages,
bool range_cyclic)
bool range_cyclic, enum wb_reason reason)
{
struct wb_writeback_work *work;
......@@ -135,6 +147,7 @@ __bdi_start_writeback(struct backing_dev_info *bdi, long nr_pages,
work->sync_mode = WB_SYNC_NONE;
work->nr_pages = nr_pages;
work->range_cyclic = range_cyclic;
work->reason = reason;
bdi_queue_work(bdi, work);
}
......@@ -150,9 +163,10 @@ __bdi_start_writeback(struct backing_dev_info *bdi, long nr_pages,
* completion. Caller need not hold sb s_umount semaphore.
*
*/
void bdi_start_writeback(struct backing_dev_info *bdi, long nr_pages)
void bdi_start_writeback(struct backing_dev_info *bdi, long nr_pages,
enum wb_reason reason)
{
__bdi_start_writeback(bdi, nr_pages, true);
__bdi_start_writeback(bdi, nr_pages, true, reason);
}
/**
......@@ -641,12 +655,14 @@ static long __writeback_inodes_wb(struct bdi_writeback *wb,
return wrote;
}
long writeback_inodes_wb(struct bdi_writeback *wb, long nr_pages)
long writeback_inodes_wb(struct bdi_writeback *wb, long nr_pages,
enum wb_reason reason)
{
struct wb_writeback_work work = {
.nr_pages = nr_pages,
.sync_mode = WB_SYNC_NONE,
.range_cyclic = 1,
.reason = reason,
};
spin_lock(&wb->list_lock);
......@@ -825,6 +841,7 @@ static long wb_check_background_flush(struct bdi_writeback *wb)
.sync_mode = WB_SYNC_NONE,
.for_background = 1,
.range_cyclic = 1,
.reason = WB_REASON_BACKGROUND,
};
return wb_writeback(wb, &work);
......@@ -858,6 +875,7 @@ static long wb_check_old_data_flush(struct bdi_writeback *wb)
.sync_mode = WB_SYNC_NONE,
.for_kupdate = 1,
.range_cyclic = 1,
.reason = WB_REASON_PERIODIC,
};
return wb_writeback(wb, &work);
......@@ -976,7 +994,7 @@ int bdi_writeback_thread(void *data)
* Start writeback of `nr_pages' pages. If `nr_pages' is zero, write back
* the whole world.
*/
void wakeup_flusher_threads(long nr_pages)
void wakeup_flusher_threads(long nr_pages, enum wb_reason reason)
{
struct backing_dev_info *bdi;
......@@ -989,7 +1007,7 @@ void wakeup_flusher_threads(long nr_pages)
list_for_each_entry_rcu(bdi, &bdi_list, bdi_list) {
if (!bdi_has_dirty_io(bdi))
continue;
__bdi_start_writeback(bdi, nr_pages, false);
__bdi_start_writeback(bdi, nr_pages, false, reason);
}
rcu_read_unlock();
}
......@@ -1210,7 +1228,9 @@ static void wait_sb_inodes(struct super_block *sb)
* on how many (if any) will be written, and this function does not wait
* for IO completion of submitted IO.
*/
void writeback_inodes_sb_nr(struct super_block *sb, unsigned long nr)
void writeback_inodes_sb_nr(struct super_block *sb,
unsigned long nr,
enum wb_reason reason)
{
DECLARE_COMPLETION_ONSTACK(done);
struct wb_writeback_work work = {
......@@ -1219,6 +1239,7 @@ void writeback_inodes_sb_nr(struct super_block *sb, unsigned long nr)
.tagged_writepages = 1,
.done = &done,
.nr_pages = nr,
.reason = reason,
};
WARN_ON(!rwsem_is_locked(&sb->s_umount));
......@@ -1235,9 +1256,9 @@ EXPORT_SYMBOL(writeback_inodes_sb_nr);
* on how many (if any) will be written, and this function does not wait
* for IO completion of submitted IO.
*/
void writeback_inodes_sb(struct super_block *sb)
void writeback_inodes_sb(struct super_block *sb, enum wb_reason reason)
{
return writeback_inodes_sb_nr(sb, get_nr_dirty_pages());
return writeback_inodes_sb_nr(sb, get_nr_dirty_pages(), reason);
}
EXPORT_SYMBOL(writeback_inodes_sb);
......@@ -1248,11 +1269,11 @@ EXPORT_SYMBOL(writeback_inodes_sb);
* Invoke writeback_inodes_sb if no writeback is currently underway.
* Returns 1 if writeback was started, 0 if not.
*/
int writeback_inodes_sb_if_idle(struct super_block *sb)
int writeback_inodes_sb_if_idle(struct super_block *sb, enum wb_reason reason)
{
if (!writeback_in_progress(sb->s_bdi)) {
down_read(&sb->s_umount);
writeback_inodes_sb(sb);
writeback_inodes_sb(sb, reason);
up_read(&sb->s_umount);
return 1;
} else
......@@ -1269,11 +1290,12 @@ EXPORT_SYMBOL(writeback_inodes_sb_if_idle);
* Returns 1 if writeback was started, 0 if not.
*/
int writeback_inodes_sb_nr_if_idle(struct super_block *sb,
unsigned long nr)
unsigned long nr,
enum wb_reason reason)
{
if (!writeback_in_progress(sb->s_bdi)) {
down_read(&sb->s_umount);
writeback_inodes_sb_nr(sb, nr);
writeback_inodes_sb_nr(sb, nr, reason);
up_read(&sb->s_umount);
return 1;
} else
......@@ -1297,6 +1319,7 @@ void sync_inodes_sb(struct super_block *sb)
.nr_pages = LONG_MAX,
.range_cyclic = 0,
.done = &done,
.reason = WB_REASON_SYNC,
};
WARN_ON(!rwsem_is_locked(&sb->s_umount));
......
......@@ -286,7 +286,7 @@ static int do_quotactl(struct super_block *sb, int type, int cmd, qid_t id,
/* caller already holds s_umount */
if (sb->s_flags & MS_RDONLY)
return -EROFS;
writeback_inodes_sb(sb);
writeback_inodes_sb(sb, WB_REASON_SYNC);
return 0;
default:
return -EINVAL;
......
......@@ -43,7 +43,7 @@ static int __sync_filesystem(struct super_block *sb, int wait)
if (wait)
sync_inodes_sb(sb);
else
writeback_inodes_sb(sb);
writeback_inodes_sb(sb, WB_REASON_SYNC);
if (sb->s_op->sync_fs)
sb->s_op->sync_fs(sb, wait);
......@@ -98,7 +98,7 @@ static void sync_filesystems(int wait)
*/
SYSCALL_DEFINE0(sync)
{
wakeup_flusher_threads(0);
wakeup_flusher_threads(0, WB_REASON_SYNC);
sync_filesystems(0);
sync_filesystems(1);
if (unlikely(laptop_mode))
......
......@@ -63,7 +63,7 @@
static void shrink_liability(struct ubifs_info *c, int nr_to_write)
{
down_read(&c->vfs_sb->s_umount);
writeback_inodes_sb(c->vfs_sb);
writeback_inodes_sb(c->vfs_sb, WB_REASON_FS_FREE_SPACE);
up_read(&c->vfs_sb->s_umount);
}
......
......@@ -118,7 +118,8 @@ int bdi_register(struct backing_dev_info *bdi, struct device *parent,
int bdi_register_dev(struct backing_dev_info *bdi, dev_t dev);
void bdi_unregister(struct backing_dev_info *bdi);
int bdi_setup_and_register(struct backing_dev_info *, char *, unsigned int);
void bdi_start_writeback(struct backing_dev_info *bdi, long nr_pages);
void bdi_start_writeback(struct backing_dev_info *bdi, long nr_pages,
enum wb_reason reason);
void bdi_start_background_writeback(struct backing_dev_info *bdi);
int bdi_writeback_thread(void *data);
int bdi_has_dirty_io(struct backing_dev_info *bdi);
......
......@@ -38,6 +38,23 @@ enum writeback_sync_modes {
WB_SYNC_ALL, /* Wait on every mapping */
};
/*
* why some writeback work was initiated
*/
enum wb_reason {
WB_REASON_BACKGROUND,
WB_REASON_TRY_TO_FREE_PAGES,
WB_REASON_SYNC,
WB_REASON_PERIODIC,
WB_REASON_LAPTOP_TIMER,
WB_REASON_FREE_MORE_MEM,
WB_REASON_FS_FREE_SPACE,
WB_REASON_FORKER_THREAD,
WB_REASON_MAX,
};
extern const char *wb_reason_name[];
/*
* A control structure which tells the writeback code what to do. These are
* always on the stack, and hence need no locking. They are always initialised
......@@ -69,14 +86,17 @@ struct writeback_control {
*/
struct bdi_writeback;
int inode_wait(void *);
void writeback_inodes_sb(struct super_block *);
void writeback_inodes_sb_nr(struct super_block *, unsigned long nr);
int writeback_inodes_sb_if_idle(struct super_block *);
int writeback_inodes_sb_nr_if_idle(struct super_block *, unsigned long nr);
void writeback_inodes_sb(struct super_block *, enum wb_reason reason);
void writeback_inodes_sb_nr(struct super_block *, unsigned long nr,
enum wb_reason reason);
int writeback_inodes_sb_if_idle(struct super_block *, enum wb_reason reason);
int writeback_inodes_sb_nr_if_idle(struct super_block *, unsigned long nr,
enum wb_reason reason);
void sync_inodes_sb(struct super_block *);
long writeback_inodes_wb(struct bdi_writeback *wb, long nr_pages);
long writeback_inodes_wb(struct bdi_writeback *wb, long nr_pages,
enum wb_reason reason);
long wb_do_writeback(struct bdi_writeback *wb, int force_wait);
void wakeup_flusher_threads(long nr_pages);
void wakeup_flusher_threads(long nr_pages, enum wb_reason reason);
/* writeback.h requires fs.h; it, too, is not included from here. */
static inline void wait_on_inode(struct inode *inode)
......
......@@ -34,6 +34,7 @@ DECLARE_EVENT_CLASS(writeback_work_class,
__field(int, for_kupdate)
__field(int, range_cyclic)
__field(int, for_background)
__field(int, reason)
),
TP_fast_assign(
strncpy(__entry->name, dev_name(bdi->dev), 32);
......@@ -43,16 +44,18 @@ DECLARE_EVENT_CLASS(writeback_work_class,
__entry->for_kupdate = work->for_kupdate;
__entry->range_cyclic = work->range_cyclic;
__entry->for_background = work->for_background;
__entry->reason = work->reason;
),
TP_printk("bdi %s: sb_dev %d:%d nr_pages=%ld sync_mode=%d "
"kupdate=%d range_cyclic=%d background=%d",
"kupdate=%d range_cyclic=%d background=%d reason=%s",
__entry->name,
MAJOR(__entry->sb_dev), MINOR(__entry->sb_dev),
__entry->nr_pages,
__entry->sync_mode,
__entry->for_kupdate,
__entry->range_cyclic,
__entry->for_background
__entry->for_background,
wb_reason_name[__entry->reason]
)
);
#define DEFINE_WRITEBACK_WORK_EVENT(name) \
......@@ -165,6 +168,7 @@ TRACE_EVENT(writeback_queue_io,
__field(unsigned long, older)
__field(long, age)
__field(int, moved)
__field(int, reason)
),
TP_fast_assign(
unsigned long *older_than_this = work->older_than_this;
......@@ -173,12 +177,14 @@ TRACE_EVENT(writeback_queue_io,
__entry->age = older_than_this ?
(jiffies - *older_than_this) * 1000 / HZ : -1;
__entry->moved = moved;
__entry->reason = work->reason;
),
TP_printk("bdi %s: older=%lu age=%ld enqueue=%d",
TP_printk("bdi %s: older=%lu age=%ld enqueue=%d reason=%s",
__entry->name,
__entry->older, /* older_than_this in jiffies */
__entry->age, /* older_than_this in relative milliseconds */
__entry->moved)
__entry->moved,
wb_reason_name[__entry->reason])
);
TRACE_EVENT(global_dirty_state,
......
......@@ -476,7 +476,8 @@ static int bdi_forker_thread(void *ptr)
* the bdi from the thread. Hopefully 1024 is
* large enough for efficient IO.
*/
writeback_inodes_wb(&bdi->wb, 1024);
writeback_inodes_wb(&bdi->wb, 1024,
WB_REASON_FORKER_THREAD);
} else {
/*
* The spinlock makes sure we do not lose
......
......@@ -1301,7 +1301,8 @@ void laptop_mode_timer_fn(unsigned long data)
* threshold
*/
if (bdi_has_dirty_io(&q->backing_dev_info))
bdi_start_writeback(&q->backing_dev_info, nr_pages);
bdi_start_writeback(&q->backing_dev_info, nr_pages,
WB_REASON_LAPTOP_TIMER);
}
/*
......
......@@ -2181,7 +2181,8 @@ static unsigned long do_try_to_free_pages(struct zonelist *zonelist,
*/
writeback_threshold = sc->nr_to_reclaim + sc->nr_to_reclaim / 2;
if (total_scanned > writeback_threshold) {
wakeup_flusher_threads(laptop_mode ? 0 : total_scanned);
wakeup_flusher_threads(laptop_mode ? 0 : total_scanned,
WB_REASON_TRY_TO_FREE_PAGES);
sc->may_writepage = 1;
}
......
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