Commit 505a666e authored by Linus Torvalds's avatar Linus Torvalds

writeback: plug writeback in wb_writeback() and writeback_inodes_wb()

We had to revert the pluggin in writeback_sb_inodes() because the
wb->list_lock is held, but we could easily plug at a higher level before
taking that lock, and unplug after releasing it.  This does that.

Chris will run performance numbers, just to verify that this approach is
comparable to the alternative (we could just drop and re-take the lock
around the blk_finish_plug() rather than these two commits.

I'd have preferred waiting for actual performance numbers before picking
one approach over the other, but I don't want to release rc1 with the
known "sleeping function called from invalid context" issue, so I'll
pick this cleanup version for now.  But if the numbers show that we
really want to plug just at the writeback_sb_inodes() level, and we
should just play ugly games with the spinlock, we'll switch to that.

Cc: Chris Mason <[email protected]>
Cc: Josef Bacik <[email protected]>
Cc: Dave Chinner <[email protected]>
Cc: Neil Brown <[email protected]>
Cc: Jan Kara <[email protected]>
Cc: Christoph Hellwig <[email protected]>
Signed-off-by: default avatarLinus Torvalds <[email protected]>
parent 0ba13fd1
...@@ -1546,12 +1546,15 @@ static long writeback_inodes_wb(struct bdi_writeback *wb, long nr_pages, ...@@ -1546,12 +1546,15 @@ static long writeback_inodes_wb(struct bdi_writeback *wb, long nr_pages,
.range_cyclic = 1, .range_cyclic = 1,
.reason = reason, .reason = reason,
}; };
struct blk_plug plug;
blk_start_plug(&plug);
spin_lock(&wb->list_lock); spin_lock(&wb->list_lock);
if (list_empty(&wb->b_io)) if (list_empty(&wb->b_io))
queue_io(wb, &work); queue_io(wb, &work);
__writeback_inodes_wb(wb, &work); __writeback_inodes_wb(wb, &work);
spin_unlock(&wb->list_lock); spin_unlock(&wb->list_lock);
blk_finish_plug(&plug);
return nr_pages - work.nr_pages; return nr_pages - work.nr_pages;
} }
...@@ -1579,10 +1582,12 @@ static long wb_writeback(struct bdi_writeback *wb, ...@@ -1579,10 +1582,12 @@ static long wb_writeback(struct bdi_writeback *wb,
unsigned long oldest_jif; unsigned long oldest_jif;
struct inode *inode; struct inode *inode;
long progress; long progress;
struct blk_plug plug;
oldest_jif = jiffies; oldest_jif = jiffies;
work->older_than_this = &oldest_jif; work->older_than_this = &oldest_jif;
blk_start_plug(&plug);
spin_lock(&wb->list_lock); spin_lock(&wb->list_lock);
for (;;) { for (;;) {
/* /*
...@@ -1662,6 +1667,7 @@ static long wb_writeback(struct bdi_writeback *wb, ...@@ -1662,6 +1667,7 @@ static long wb_writeback(struct bdi_writeback *wb,
} }
} }
spin_unlock(&wb->list_lock); spin_unlock(&wb->list_lock);
blk_finish_plug(&plug);
return nr_pages - work->nr_pages; return nr_pages - work->nr_pages;
} }
......
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