Commit dd73e4b7 authored by Tejun Heo's avatar Tejun Heo Committed by Jens Axboe

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 <>
Signed-off-by: default avatarJens Axboe <>
parent 412a19b6
......@@ -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)) {
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)
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) {
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