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authorRoman Gushchin <guro@fb.com>2021-06-28 19:35:53 -0700
committerLinus Torvalds <torvalds@linux-foundation.org>2021-06-29 10:53:48 -0700
commitf3b6a6df38aa514d97e8c6fcc748be1d4142bec9 (patch)
tree0e2f7f1bb9700866f5b424dbb75af5222ecb626e /fs
parent29264d92a0f157f3147129066d912718b99fc6b0 (diff)
writeback, cgroup: keep list of inodes attached to bdi_writeback
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. Link: https://lkml.kernel.org/r/20210608230225.2078447-6-guro@fb.com Signed-off-by: Roman Gushchin <guro@fb.com> Suggested-by: Jan Kara <jack@suse.cz> Reviewed-by: Jan Kara <jack@suse.cz> Acked-by: Tejun Heo <tj@kernel.org> Acked-by: Dennis Zhou <dennis@kernel.org> Cc: Alexander Viro <viro@zeniv.linux.org.uk> Cc: Dave Chinner <dchinner@redhat.com> Cc: Jan Kara <jack@suse.com> Cc: Jens Axboe <axboe@kernel.dk> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'fs')
-rw-r--r--fs/fs-writeback.c93
1 files changed, 59 insertions, 34 deletions
diff --git a/fs/fs-writeback.c b/fs/fs-writeback.c
index 96974e13a203..87b305ee5348 100644
--- a/fs/fs-writeback.c
+++ b/fs/fs-writeback.c
@@ -131,25 +131,6 @@ static bool inode_io_list_move_locked(struct inode *inode,
return false;
}
-/**
- * inode_io_list_del_locked - remove an inode from its bdi_writeback IO list
- * @inode: inode to be removed
- * @wb: bdi_writeback @inode is being removed from
- *
- * Remove @inode which may be on one of @wb->b_{dirty|io|more_io} lists and
- * clear %WB_has_dirty_io if all are empty afterwards.
- */
-static void inode_io_list_del_locked(struct inode *inode,
- struct bdi_writeback *wb)
-{
- assert_spin_locked(&wb->list_lock);
- assert_spin_locked(&inode->i_lock);
-
- inode->i_state &= ~I_SYNC_QUEUED;
- list_del_init(&inode->i_io_list);
- wb_io_lists_depopulated(wb);
-}
-
static void wb_wakeup(struct bdi_writeback *wb)
{
spin_lock_bh(&wb->work_lock);
@@ -279,6 +260,28 @@ void __inode_attach_wb(struct inode *inode, struct page *page)
EXPORT_SYMBOL_GPL(__inode_attach_wb);
/**
+ * inode_cgwb_move_to_attached - put the inode onto wb->b_attached list
+ * @inode: inode of interest with i_lock held
+ * @wb: target bdi_writeback
+ *
+ * Remove the inode from wb's io lists and if necessarily put onto b_attached
+ * list. Only inodes attached to cgwb's are kept on this list.
+ */
+static void inode_cgwb_move_to_attached(struct inode *inode,
+ struct bdi_writeback *wb)
+{
+ assert_spin_locked(&wb->list_lock);
+ assert_spin_locked(&inode->i_lock);
+
+ inode->i_state &= ~I_SYNC_QUEUED;
+ if (wb != &wb->bdi->wb)
+ list_move(&inode->i_io_list, &wb->b_attached);
+ else
+ list_del_init(&inode->i_io_list);
+ wb_io_lists_depopulated(wb);
+}
+
+/**
* locked_inode_to_wb_and_lock_list - determine a locked inode's wb and lock it
* @inode: inode of interest with i_lock held
*
@@ -418,21 +421,28 @@ static void inode_switch_wbs_work_fn(struct work_struct *work)
wb_get(new_wb);
/*
- * Transfer to @new_wb's IO list if necessary. The specific list
- * @inode was on is ignored and the inode is put on ->b_dirty which
- * is always correct including from ->b_dirty_time. The transfer
- * preserves @inode->dirtied_when ordering.
+ * Transfer to @new_wb's IO list if necessary. If the @inode is dirty,
+ * the specific list @inode was on is ignored and the @inode is put on
+ * ->b_dirty which is always correct including from ->b_dirty_time.
+ * The transfer preserves @inode->dirtied_when ordering. If the @inode
+ * was clean, it means it was on the b_attached list, so move it onto
+ * the b_attached list of @new_wb.
*/
if (!list_empty(&inode->i_io_list)) {
- struct inode *pos;
-
- inode_io_list_del_locked(inode, old_wb);
inode->i_wb = new_wb;
- list_for_each_entry(pos, &new_wb->b_dirty, i_io_list)
- if (time_after_eq(inode->dirtied_when,
- pos->dirtied_when))
- break;
- inode_io_list_move_locked(inode, new_wb, pos->i_io_list.prev);
+
+ if (inode->i_state & I_DIRTY_ALL) {
+ struct inode *pos;
+
+ list_for_each_entry(pos, &new_wb->b_dirty, i_io_list)
+ if (time_after_eq(inode->dirtied_when,
+ pos->dirtied_when))
+ break;
+ inode_io_list_move_locked(inode, new_wb,
+ pos->i_io_list.prev);
+ } else {
+ inode_cgwb_move_to_attached(inode, new_wb);
+ }
} else {
inode->i_wb = new_wb;
}
@@ -1021,6 +1031,17 @@ 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)
+{
+ assert_spin_locked(&wb->list_lock);
+ assert_spin_locked(&inode->i_lock);
+
+ inode->i_state &= ~I_SYNC_QUEUED;
+ list_del_init(&inode->i_io_list);
+ wb_io_lists_depopulated(wb);
+}
+
static struct bdi_writeback *
locked_inode_to_wb_and_lock_list(struct inode *inode)
__releases(&inode->i_lock)
@@ -1121,7 +1142,11 @@ void inode_io_list_del(struct inode *inode)
wb = inode_to_wb_and_lock_list(inode);
spin_lock(&inode->i_lock);
- inode_io_list_del_locked(inode, wb);
+
+ inode->i_state &= ~I_SYNC_QUEUED;
+ list_del_init(&inode->i_io_list);
+ wb_io_lists_depopulated(wb);
+
spin_unlock(&inode->i_lock);
spin_unlock(&wb->list_lock);
}
@@ -1434,7 +1459,7 @@ static void requeue_inode(struct inode *inode, struct bdi_writeback *wb,
inode->i_state &= ~I_SYNC_QUEUED;
} else {
/* The inode is clean. Remove from writeback lists. */
- inode_io_list_del_locked(inode, wb);
+ inode_cgwb_move_to_attached(inode, wb);
}
}
@@ -1586,7 +1611,7 @@ static int writeback_single_inode(struct inode *inode,
* responsible for the writeback lists.
*/
if (!(inode->i_state & I_DIRTY_ALL))
- inode_io_list_del_locked(inode, wb);
+ inode_cgwb_move_to_attached(inode, wb);
spin_unlock(&wb->list_lock);
inode_sync_complete(inode);
out: