long nr_pages;
struct super_block *sb;
enum writeback_sync_modes sync_mode;
- int for_kupdate;
- int range_cyclic;
+ int for_kupdate:1;
+ int range_cyclic:1;
+ int for_background:1;
};
/*
.range_cyclic = 1,
};
+ /*
+ * We treat @nr_pages=0 as the special case to do background writeback,
+ * ie. to sync pages until the background dirty threshold is reached.
+ */
+ if (!nr_pages) {
+ args.nr_pages = LONG_MAX;
+ args.for_background = 1;
+ }
+
bdi_alloc_queue_work(bdi, &args);
}
* For inodes being constantly redirtied, dirtied_when can get stuck.
* It _appears_ to be in the future, but is actually in distant past.
* This test is necessary to prevent such wrapped-around relative times
- * from permanently stopping the whole pdflush writeback.
+ * from permanently stopping the whole bdi writeback.
*/
ret = ret && time_before_eq(inode->dirtied_when, jiffies);
#endif
struct list_head *dispatch_queue,
unsigned long *older_than_this)
{
+ LIST_HEAD(tmp);
+ struct list_head *pos, *node;
+ struct super_block *sb = NULL;
+ struct inode *inode;
+ int do_sb_sort = 0;
+
while (!list_empty(delaying_queue)) {
- struct inode *inode = list_entry(delaying_queue->prev,
- struct inode, i_list);
+ inode = list_entry(delaying_queue->prev, struct inode, i_list);
if (older_than_this &&
inode_dirtied_after(inode, *older_than_this))
break;
- list_move(&inode->i_list, dispatch_queue);
+ if (sb && sb != inode->i_sb)
+ do_sb_sort = 1;
+ sb = inode->i_sb;
+ list_move(&inode->i_list, &tmp);
+ }
+
+ /* just one sb in list, splice to dispatch_queue and we're done */
+ if (!do_sb_sort) {
+ list_splice(&tmp, dispatch_queue);
+ return;
+ }
+
+ /* Move inodes from one superblock together */
+ while (!list_empty(&tmp)) {
+ inode = list_entry(tmp.prev, struct inode, i_list);
+ sb = inode->i_sb;
+ list_for_each_prev_safe(pos, node, &tmp) {
+ inode = list_entry(pos, struct inode, i_list);
+ if (inode->i_sb == sb)
+ list_move(&inode->i_list, dispatch_queue);
+ }
}
}
spin_lock(&inode_lock);
inode->i_state &= ~I_SYNC;
if (!(inode->i_state & (I_FREEING | I_CLEAR))) {
- if (!(inode->i_state & I_DIRTY) &&
- mapping_tagged(mapping, PAGECACHE_TAG_DIRTY)) {
+ if ((inode->i_state & I_DIRTY_PAGES) && wbc->for_kupdate) {
+ /*
+ * More pages get dirtied by a fast dirtier.
+ */
+ goto select_queue;
+ } else if (inode->i_state & I_DIRTY) {
+ /*
+ * At least XFS will redirty the inode during the
+ * writeback (delalloc) and on io completion (isize).
+ */
+ redirty_tail(inode);
+ } else if (mapping_tagged(mapping, PAGECACHE_TAG_DIRTY)) {
/*
* We didn't write back all the pages. nfs_writepages()
* sometimes bales out without doing anything. Redirty
* soon as the queue becomes uncongested.
*/
inode->i_state |= I_DIRTY_PAGES;
+select_queue:
if (wbc->nr_to_write <= 0) {
/*
* slice used up: queue for next turn
inode->i_state |= I_DIRTY_PAGES;
redirty_tail(inode);
}
- } else if (inode->i_state & I_DIRTY) {
- /*
- * Someone redirtied the inode while were writing back
- * the pages.
- */
- redirty_tail(inode);
} else if (atomic_read(&inode->i_count)) {
/*
* The inode is clean, inuse
return ret;
}
+static void unpin_sb_for_writeback(struct super_block **psb)
+{
+ struct super_block *sb = *psb;
+
+ if (sb) {
+ up_read(&sb->s_umount);
+ put_super(sb);
+ *psb = NULL;
+ }
+}
+
/*
* For WB_SYNC_NONE writeback, the caller does not have the sb pinned
* before calling writeback. So make sure that we do pin it, so it doesn't
* 1 if we failed.
*/
static int pin_sb_for_writeback(struct writeback_control *wbc,
- struct inode *inode)
+ struct inode *inode, struct super_block **psb)
{
struct super_block *sb = inode->i_sb;
+ /*
+ * If this sb is already pinned, nothing more to do. If not and
+ * *psb is non-NULL, unpin the old one first
+ */
+ if (sb == *psb)
+ return 0;
+ else if (*psb)
+ unpin_sb_for_writeback(psb);
+
/*
* Caller must already hold the ref for this
*/
if (down_read_trylock(&sb->s_umount)) {
if (sb->s_root) {
spin_unlock(&sb_lock);
- return 0;
+ goto pinned;
}
/*
* umounted, drop rwsem again and fall through to failure
sb->s_count--;
spin_unlock(&sb_lock);
return 1;
-}
-
-static void unpin_sb_for_writeback(struct writeback_control *wbc,
- struct inode *inode)
-{
- struct super_block *sb = inode->i_sb;
-
- if (wbc->sync_mode == WB_SYNC_ALL)
- return;
-
- up_read(&sb->s_umount);
- put_super(sb);
+pinned:
+ *psb = sb;
+ return 0;
}
static void writeback_inodes_wb(struct bdi_writeback *wb,
struct writeback_control *wbc)
{
- struct super_block *sb = wbc->sb;
+ struct super_block *sb = wbc->sb, *pin_sb = NULL;
const int is_blkdev_sb = sb_is_blkdev_sb(sb);
const unsigned long start = jiffies; /* livelock avoidance */
if (inode_dirtied_after(inode, start))
break;
- if (pin_sb_for_writeback(wbc, inode)) {
+ if (pin_sb_for_writeback(wbc, inode, &pin_sb)) {
requeue_io(inode);
continue;
}
__iget(inode);
pages_skipped = wbc->pages_skipped;
writeback_single_inode(inode, wbc);
- unpin_sb_for_writeback(wbc, inode);
if (wbc->pages_skipped != pages_skipped) {
/*
* writeback is not making progress due to locked
wbc->more_io = 1;
}
+ unpin_sb_for_writeback(&pin_sb);
+
spin_unlock(&inode_lock);
/* Leave any unwritten inodes on b_io */
}
};
unsigned long oldest_jif;
long wrote = 0;
+ struct inode *inode;
if (wbc.for_kupdate) {
wbc.older_than_this = &oldest_jif;
for (;;) {
/*
- * Don't flush anything for non-integrity writeback where
- * no nr_pages was given
+ * Stop writeback when nr_pages has been consumed
*/
- if (!args->for_kupdate && args->nr_pages <= 0 &&
- args->sync_mode == WB_SYNC_NONE)
+ if (args->nr_pages <= 0)
break;
/*
- * If no specific pages were given and this is just a
- * periodic background writeout and we are below the
- * background dirty threshold, don't do anything
+ * For background writeout, stop when we are below the
+ * background dirty threshold
*/
- if (args->for_kupdate && args->nr_pages <= 0 &&
- !over_bground_thresh())
+ if (args->for_background && !over_bground_thresh())
break;
wbc.more_io = 0;
wrote += MAX_WRITEBACK_PAGES - wbc.nr_to_write;
/*
- * If we ran out of stuff to write, bail unless more_io got set
+ * If we consumed everything, see if we have more
*/
- if (wbc.nr_to_write > 0 || wbc.pages_skipped > 0) {
- if (wbc.more_io && !wbc.for_kupdate)
- continue;
+ if (wbc.nr_to_write <= 0)
+ continue;
+ /*
+ * Didn't write everything and we don't have more IO, bail
+ */
+ if (!wbc.more_io)
break;
+ /*
+ * Did we write something? Try for more
+ */
+ if (wbc.nr_to_write < MAX_WRITEBACK_PAGES)
+ continue;
+ /*
+ * Nothing written. Wait for some inode to
+ * become available for writeback. Otherwise
+ * we'll just busyloop.
+ */
+ spin_lock(&inode_lock);
+ if (!list_empty(&wb->b_more_io)) {
+ inode = list_entry(wb->b_more_io.prev,
+ struct inode, i_list);
+ inode_wait_for_writeback(inode);
}
+ spin_unlock(&inode_lock);
}
return wrote;
* If older_than_this is non-NULL, then only write out inodes which
* had their first dirtying at a time earlier than *older_than_this.
*
- * If we're a pdlfush thread, then implement pdflush collision avoidance
- * against the entire list.
- *
* If `bdi' is non-zero then we're being asked to writeback a specific queue.
* This function assumes that the blockdev superblock's inodes are backed by
* a variety of queues, so all inodes are searched. For other superblocks,
nr_to_write = nr_dirty + nr_unstable +
(inodes_stat.nr_inodes - inodes_stat.nr_unused);
- bdi_writeback_all(sb, nr_to_write);
+ bdi_start_writeback(sb->s_bdi, nr_to_write);
}
EXPORT_SYMBOL(writeback_inodes_sb);
/*
* When balance_dirty_pages decides that the caller needs to perform some
* non-background writeback, this is how many pages it will attempt to write.
- * It should be somewhat larger than RATELIMIT_PAGES to ensure that reasonably
+ * It should be somewhat larger than dirtied pages to ensure that reasonably
* large amounts of I/O are submitted.
*/
-static inline long sync_writeback_pages(void)
+static inline long sync_writeback_pages(unsigned long dirtied)
{
- return ratelimit_pages + ratelimit_pages / 2;
+ if (dirtied < ratelimit_pages)
+ dirtied = ratelimit_pages;
+
+ return dirtied + dirtied / 2;
}
/* The following parameters are exported via /proc/sys/vm */
/*
- * Start background writeback (via pdflush) at this percentage
+ * Start background writeback (via writeback threads) at this percentage
*/
int dirty_background_ratio = 10;
* balance_dirty_pages() must be called by processes which are generating dirty
* data. It looks at the number of dirty pages in the machine and will force
* the caller to perform writeback if the system is over `vm_dirty_ratio'.
- * If we're over `background_thresh' then pdflush is woken to perform some
- * writeout.
+ * If we're over `background_thresh' then the writeback threads are woken to
+ * perform some writeout.
*/
-static void balance_dirty_pages(struct address_space *mapping)
+static void balance_dirty_pages(struct address_space *mapping,
+ unsigned long write_chunk)
{
long nr_reclaimable, bdi_nr_reclaimable;
long nr_writeback, bdi_nr_writeback;
unsigned long dirty_thresh;
unsigned long bdi_thresh;
unsigned long pages_written = 0;
- unsigned long write_chunk = sync_writeback_pages();
unsigned long pause = 1;
struct backing_dev_info *bdi = mapping->backing_dev_info;
bdi->dirty_exceeded = 0;
if (writeback_in_progress(bdi))
- return; /* pdflush is already working this queue */
+ return;
/*
* In laptop mode, we wait until hitting the higher threshold before
* background_thresh, to keep the amount of dirty memory low.
*/
if ((laptop_mode && pages_written) ||
- (!laptop_mode && ((nr_writeback = global_page_state(NR_FILE_DIRTY)
- + global_page_state(NR_UNSTABLE_NFS))
+ (!laptop_mode && ((global_page_state(NR_FILE_DIRTY)
+ + global_page_state(NR_UNSTABLE_NFS))
> background_thresh)))
- bdi_start_writeback(bdi, nr_writeback);
+ bdi_start_writeback(bdi, 0);
}
void set_page_dirty_balance(struct page *page, int page_mkwrite)
p = &__get_cpu_var(bdp_ratelimits);
*p += nr_pages_dirtied;
if (unlikely(*p >= ratelimit)) {
+ ratelimit = sync_writeback_pages(*p);
*p = 0;
preempt_enable();
- balance_dirty_pages(mapping);
+ balance_dirty_pages(mapping, ratelimit);
return;
}
preempt_enable();
projects / linux-block.git / commitdiff