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authorTejun Heo <tj@kernel.org>2015-05-23 00:13:50 +0300
committerJens Axboe <axboe@fb.com>2015-06-02 17:33:36 +0300
commitebe41ab0c79d5633123f6faa3265a1a63c5f22d8 (patch)
tree9d4722bb9c41a8713b76db30ddbbe625a8c5ce8b /include/linux/backing-dev.h
parent693108a8a6672cec88265d83f7187dc83ba1d6a3 (diff)
downloadlinux-ebe41ab0c79d5633123f6faa3265a1a63c5f22d8.tar.xz
writeback: implement bdi_for_each_wb()
This will be used to implement bdi-wide operations which should be distributed across all its cgroup bdi_writebacks. Signed-off-by: Tejun Heo <tj@kernel.org> Cc: Jens Axboe <axboe@kernel.dk> Cc: Jan Kara <jack@suse.cz> Signed-off-by: Jens Axboe <axboe@fb.com>
Diffstat (limited to 'include/linux/backing-dev.h')
-rw-r--r--include/linux/backing-dev.h63
1 files changed, 63 insertions, 0 deletions
diff --git a/include/linux/backing-dev.h b/include/linux/backing-dev.h
index 0839e44105bd..c7979806baee 100644
--- a/include/linux/backing-dev.h
+++ b/include/linux/backing-dev.h
@@ -383,6 +383,61 @@ static inline struct bdi_writeback *inode_to_wb(struct inode *inode)
return inode->i_wb;
}
+struct wb_iter {
+ int start_blkcg_id;
+ struct radix_tree_iter tree_iter;
+ void **slot;
+};
+
+static inline struct bdi_writeback *__wb_iter_next(struct wb_iter *iter,
+ struct backing_dev_info *bdi)
+{
+ struct radix_tree_iter *titer = &iter->tree_iter;
+
+ WARN_ON_ONCE(!rcu_read_lock_held());
+
+ if (iter->start_blkcg_id >= 0) {
+ iter->slot = radix_tree_iter_init(titer, iter->start_blkcg_id);
+ iter->start_blkcg_id = -1;
+ } else {
+ iter->slot = radix_tree_next_slot(iter->slot, titer, 0);
+ }
+
+ if (!iter->slot)
+ iter->slot = radix_tree_next_chunk(&bdi->cgwb_tree, titer, 0);
+ if (iter->slot)
+ return *iter->slot;
+ return NULL;
+}
+
+static inline struct bdi_writeback *__wb_iter_init(struct wb_iter *iter,
+ struct backing_dev_info *bdi,
+ int start_blkcg_id)
+{
+ iter->start_blkcg_id = start_blkcg_id;
+
+ if (start_blkcg_id)
+ return __wb_iter_next(iter, bdi);
+ else
+ return &bdi->wb;
+}
+
+/**
+ * bdi_for_each_wb - walk all wb's of a bdi in ascending blkcg ID order
+ * @wb_cur: cursor struct bdi_writeback pointer
+ * @bdi: bdi to walk wb's of
+ * @iter: pointer to struct wb_iter to be used as iteration buffer
+ * @start_blkcg_id: blkcg ID to start iteration from
+ *
+ * Iterate @wb_cur through the wb's (bdi_writeback's) of @bdi in ascending
+ * blkcg ID order starting from @start_blkcg_id. @iter is struct wb_iter
+ * to be used as temp storage during iteration. rcu_read_lock() must be
+ * held throughout iteration.
+ */
+#define bdi_for_each_wb(wb_cur, bdi, iter, start_blkcg_id) \
+ for ((wb_cur) = __wb_iter_init(iter, bdi, start_blkcg_id); \
+ (wb_cur); (wb_cur) = __wb_iter_next(iter, bdi))
+
#else /* CONFIG_CGROUP_WRITEBACK */
static inline bool inode_cgwb_enabled(struct inode *inode)
@@ -445,6 +500,14 @@ static inline void wb_blkcg_offline(struct blkcg *blkcg)
{
}
+struct wb_iter {
+ int next_id;
+};
+
+#define bdi_for_each_wb(wb_cur, bdi, iter, start_blkcg_id) \
+ for ((iter)->next_id = (start_blkcg_id); \
+ ({ (wb_cur) = !(iter)->next_id++ ? &(bdi)->wb : NULL; }); )
+
static inline int inode_congested(struct inode *inode, int cong_bits)
{
return wb_congested(&inode_to_bdi(inode)->wb, cong_bits);