Re: [PATCH v6 2/5] writeback, cgroup: keep list of inodes attached to bdi_writeback
From: Jan Kara <jack@suse.cz>
Date: 2021-06-03 08:55:36
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cgroups, linux-fsdevel, lkml
On Wed 02-06-21 17:55:14, Roman Gushchin wrote:
Currently there is no way to iterate over inodes attached to a specific cgwb structure. It limits the ability to efficiently reclaim the writeback structure itself and associated memory and block cgroup structures without scanning all inodes belonging to a sb, which can be prohibitively expensive. While dirty/in-active-writeback an inode belongs to one of the bdi_writeback's io lists: b_dirty, b_io, b_more_io and b_dirty_time. Once cleaned up, it's removed from all io lists. So the inode->i_io_list can be reused to maintain the list of inodes, attached to a bdi_writeback structure. This patch introduces a new wb->b_attached list, which contains all inodes which were dirty at least once and are attached to the given cgwb. Inodes attached to the root bdi_writeback structures are never placed on such list. The following patch will use this list to try to release cgwbs structures more efficiently. Suggested-by: Jan Kara <jack@suse.cz> Signed-off-by: Roman Gushchin <redacted>
Looks good, just one small comment below, with that fixed feel free to add: Reviewed-by: Jan Kara <jack@suse.cz> ...
quoted hunk ↗ jump to hunk
@@ -1014,6 +1024,12 @@ fs_initcall(cgroup_writeback_init); static void bdi_down_write_wb_switch_rwsem(struct backing_dev_info *bdi) { } static void bdi_up_write_wb_switch_rwsem(struct backing_dev_info *bdi) { } +static void inode_cgwb_move_to_attached(struct inode *inode, + struct bdi_writeback *wb) +{ + list_del_init(&inode->i_io_list); +} +
I think you miss clearing of I_SYNC_QUEUED here. Also you could add here the lock assertions that are in the other version of inode_cgwb_move_to_attached(). Honza -- Jan Kara [off-list ref] SUSE Labs, CR