[PATCH 10/10] writeback: use spin_trylock() in bdi_writeback_all() for WB_SYNC_NONE

Jens Axboe
2009-06-17T11:09:57Z

Not sure whether this is a good idea, hence it's at the back of the
series as a separate patch. In theory it should be fine, since all
WB_SYNC_NONE writeback is best-effort. No guarentees are made.

Signed-off-by: Jens Axboe <jens.axboe@oracle.com>
---
fs/fs-writeback.c | 13 +++++++++++--
1 files changed, 11 insertions(+), 2 deletions(-)

diff --git a/fs/fs-writeback.c b/fs/fs-writeback.c
index de5f7ef..d589db3 100644
--- a/fs/fs-writeback.c
+++ b/fs/fs-writeback.c
@@ -506,9 +506,17 @@ void bdi_writeback_all(struct super_block *sb, struct writeback_control *wbc)
struct bdi_work *work;
LIST_HEAD(list);

-restart:
- spin_lock(&bdi_lock);
+ /*
+ * If this isn't a data integrity writeback, just drop it if
+ * someone is already holding the bdi_lock
+ */
+ if (!spin_trylock(&bdi_lock)) {
+ if (!must_wait)
+ return;
+ spin_lock(&bdi_lock);
+ }

+restart:
list_for_each_entry(bdi, &bdi_list, bdi_list) {
struct bdi_work *work;

@@ -535,6 +543,7 @@ restart:
__wbc = *wbc;
__wbc.bdi = bdi;
generic_sync_bdi_inodes(sb, &__wbc);
+ spin_lock(&bdi_lock);
goto restart;
}
if (must_wait)
--
1.6.3.rc0.1.gf800