};
unsigned long oldest_jif;
long wrote = 0;
+ long write_chunk;
struct inode *inode;
if (wbc.for_kupdate) {
wbc.range_end = LLONG_MAX;
}
+ /*
+ * WB_SYNC_ALL mode does livelock avoidance by syncing dirty
+ * inodes/pages in one big loop. Setting wbc.nr_to_write=LONG_MAX
+ * here avoids calling into writeback_inodes_wb() more than once.
+ *
+ * The intended call sequence for WB_SYNC_ALL writeback is:
+ *
+ * wb_writeback()
+ * __writeback_inodes_sb() <== called only once
+ * write_cache_pages() <== called once for each inode
+ * (quickly) tag currently dirty pages
+ * (maybe slowly) sync all tagged pages
+ */
+ if (wbc.sync_mode == WB_SYNC_NONE)
+ write_chunk = MAX_WRITEBACK_PAGES;
+ else
+ write_chunk = LONG_MAX;
+
wbc.wb_start = jiffies; /* livelock avoidance */
for (;;) {
/*
if (work->nr_pages <= 0)
break;
+ /*
+ * Background writeout and kupdate-style writeback may
+ * run forever. Stop them if there is other work to do
+ * so that e.g. sync can proceed. They'll be restarted
+ * after the other works are all done.
+ */
+ if ((work->for_background || work->for_kupdate) &&
+ !list_empty(&wb->bdi->work_list))
+ break;
+
/*
* For background writeout, stop when we are below the
* background dirty threshold
break;
wbc.more_io = 0;
- wbc.nr_to_write = MAX_WRITEBACK_PAGES;
+ wbc.nr_to_write = write_chunk;
wbc.pages_skipped = 0;
trace_wbc_writeback_start(&wbc, wb->bdi);
writeback_inodes_wb(wb, &wbc);
trace_wbc_writeback_written(&wbc, wb->bdi);
- work->nr_pages -= MAX_WRITEBACK_PAGES - wbc.nr_to_write;
- wrote += MAX_WRITEBACK_PAGES - wbc.nr_to_write;
+ work->nr_pages -= write_chunk - wbc.nr_to_write;
+ wrote += write_chunk - wbc.nr_to_write;
/*
* If we consumed everything, see if we have more
/*
* Did we write something? Try for more
*/
- if (wbc.nr_to_write < MAX_WRITEBACK_PAGES)
+ if (wbc.nr_to_write < write_chunk)
continue;
/*
* Nothing written. Wait for some inode to
* @sb: the superblock
*
* This function writes and waits on any dirty inode belonging to this
- * super_block. The number of pages synced is returned.
+ * super_block.
*/
void sync_inodes_sb(struct super_block *sb)
{
EXPORT_SYMBOL(sync_inode);
/**
- * sync_inode - write an inode to disk
+ * sync_inode_metadata - write an inode to disk
* @inode: the inode to sync
* @wait: wait for I/O to complete.
*
- * Write an inode to disk and adjust it's dirty state after completion.
+ * Write an inode to disk and adjust its dirty state after completion.
*
* Note: only writes the actual inode, no associated data or other metadata.
*/