Add new functions for triggering inode writeback
When btrfs is running low on metadata space, it needs to force delayed
allocation pages to disk. It currently does this with a suboptimal walk
of a private list of inodes with delayed allocation, and it would be
much better if we used the generic flusher threads.
writeback_inodes_sb_if_idle would be ideal, but it waits for the flusher
thread to start IO on all the dirty pages in the FS before it returns.
This adds variants of writeback_inodes_sb* that allow the caller to
control how many pages get sent down.
Signed-off-by: Chris Mason <chris.mason@oracle.com>
diff --git a/fs/fs-writeback.c b/fs/fs-writeback.c
index ab38fef..1e23c33 100644
--- a/fs/fs-writeback.c
+++ b/fs/fs-writeback.c
@@ -1069,33 +1069,44 @@
}
/**
- * writeback_inodes_sb - writeback dirty inodes from given super_block
+ * writeback_inodes_sb_nr - writeback dirty inodes from given super_block
* @sb: the superblock
+ * @nr: the number of pages to write
*
* Start writeback on some inodes on this super_block. No guarantees are made
* on how many (if any) will be written, and this function does not wait
- * for IO completion of submitted IO. The number of pages submitted is
- * returned.
+ * for IO completion of submitted IO.
*/
-void writeback_inodes_sb(struct super_block *sb)
+void writeback_inodes_sb_nr(struct super_block *sb, unsigned long nr)
{
- unsigned long nr_dirty = global_page_state(NR_FILE_DIRTY);
- unsigned long nr_unstable = global_page_state(NR_UNSTABLE_NFS);
DECLARE_COMPLETION_ONSTACK(done);
struct wb_writeback_work work = {
.sb = sb,
.sync_mode = WB_SYNC_NONE,
.done = &done,
+ .nr_pages = nr,
};
WARN_ON(!rwsem_is_locked(&sb->s_umount));
-
- work.nr_pages = nr_dirty + nr_unstable +
- (inodes_stat.nr_inodes - inodes_stat.nr_unused);
-
bdi_queue_work(sb->s_bdi, &work);
wait_for_completion(&done);
}
+EXPORT_SYMBOL(writeback_inodes_sb_nr);
+
+/**
+ * writeback_inodes_sb - writeback dirty inodes from given super_block
+ * @sb: the superblock
+ *
+ * Start writeback on some inodes on this super_block. No guarantees are made
+ * on how many (if any) will be written, and this function does not wait
+ * for IO completion of submitted IO.
+ */
+void writeback_inodes_sb(struct super_block *sb)
+{
+ return writeback_inodes_sb_nr(sb, global_page_state(NR_FILE_DIRTY) +
+ global_page_state(NR_UNSTABLE_NFS) +
+ (inodes_stat.nr_inodes - inodes_stat.nr_unused));
+}
EXPORT_SYMBOL(writeback_inodes_sb);
/**
@@ -1118,6 +1129,27 @@
EXPORT_SYMBOL(writeback_inodes_sb_if_idle);
/**
+ * writeback_inodes_sb_if_idle - start writeback if none underway
+ * @sb: the superblock
+ * @nr: the number of pages to write
+ *
+ * Invoke writeback_inodes_sb if no writeback is currently underway.
+ * Returns 1 if writeback was started, 0 if not.
+ */
+int writeback_inodes_sb_nr_if_idle(struct super_block *sb,
+ unsigned long nr)
+{
+ if (!writeback_in_progress(sb->s_bdi)) {
+ down_read(&sb->s_umount);
+ writeback_inodes_sb_nr(sb, nr);
+ up_read(&sb->s_umount);
+ return 1;
+ } else
+ return 0;
+}
+EXPORT_SYMBOL(writeback_inodes_sb_nr_if_idle);
+
+/**
* sync_inodes_sb - sync sb inode pages
* @sb: the superblock
*