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Commit dd73e4b7 authored by Tejun Heo's avatar Tejun Heo Committed by Jens Axboe
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writeback: do foreign inode detection iff cgroup writeback is enabled 



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: default avatarTejun Heo <tj@kernel.org>
Signed-off-by: default avatarJens Axboe <axboe@fb.com>
parent 412a19b6

fs/fs-writeback.c

+13 −3
Original line number Diff line number Diff line
@@ -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) {