Currently, even when a filesystem doesn't set the FS_CGROUP_WRITEBACK
flag, if the filesystem uses wbc_init_bio() and wbc_account_io(), the
foreign inode detection and migration logic still ends up activating
cgroup writeback which is unexpected. This patch ensures that the
foreign inode detection logic stays disabled when inode_cgwb_enabled()
is false by not associating writeback_control's with bdi_writeback's.
This also avoids unnecessary operations in wbc_init_bio(),
wbc_account_io() and wbc_detach_inode() for filesystems which don't
support cgroup writeback.
Signed-off-by: Tejun Heo <tj@xxxxxxxxxx>
---
fs/fs-writeback.c | 16 +++++++++++++---
1 file changed, 13 insertions(+), 3 deletions(-)
diff --git a/fs/fs-writeback.c b/fs/fs-writeback.c
index f60de54..f0520bc 100644
--- a/fs/fs-writeback.c
+++ b/fs/fs-writeback.c
@@ -513,6 +513,11 @@ static void inode_switch_wbs(struct inode *inode, int new_wb_id)
void wbc_attach_and_unlock_inode(struct writeback_control *wbc,
struct inode *inode)
{
+ if (!inode_cgwb_enabled(inode)) {
+ spin_unlock(&inode->i_lock);
+ return;
+ }
+
wbc->wb = inode_to_wb(inode);
wbc->inode = inode;
@@ -575,11 +580,16 @@ void wbc_detach_inode(struct writeback_control *wbc)
{
struct bdi_writeback *wb = wbc->wb;
struct inode *inode = wbc->inode;
- u16 history = inode->i_wb_frn_history;
- unsigned long avg_time = inode->i_wb_frn_avg_time;
- unsigned long max_bytes, max_time;
+ unsigned long avg_time, max_bytes, max_time;
+ u16 history;
int max_id;
+ if (!wb)
+ return;
+
+ history = inode->i_wb_frn_history;
+ avg_time = inode->i_wb_frn_avg_time;
+
/* pick the winner of this round */
if (wbc->wb_bytes >= wbc->wb_lcand_bytes &&
wbc->wb_bytes >= wbc->wb_tcand_bytes) {
--
2.4.2
--
To unsubscribe from this list: send the line "unsubscribe linux-fsdevel" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at http://vger.kernel.org/majordomo-info.html
