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authorEric Sandeen <sandeen@redhat.com>2009-12-23 07:57:07 -0500
committerTheodore Ts'o <tytso@mit.edu>2009-12-23 07:57:07 -0500
commit17bd55d037a02b04d9119511cfd1a4b985d20f63 (patch)
treeddbc227fffb84d1b95f5f8c48b627f88f3fd56ed
parentd3533d72e7478a61a3e1936956fc825289a2acf4 (diff)
fs-writeback: Add helper function to start writeback if idle
ext4, at least, would like to start pushing on writeback if it starts to get close to ENOSPC when reserving worst-case blocks for delalloc writes. Writing out delalloc data will convert those worst-case predictions into usually smaller actual usage, freeing up space before we hit ENOSPC based on this speculation. Thanks to Jens for the suggestion for the helper function, & the naming help. I've made the helper return status on whether writeback was started even though I don't plan to use it in the ext4 patch; it seems like it would be potentially useful to test this in some cases. Signed-off-by: Eric Sandeen <sandeen@redhat.com> Acked-by: Jan Kara <jack@suse.cz>
-rw-r--r--fs/fs-writeback.c17
-rw-r--r--include/linux/writeback.h1
2 files changed, 18 insertions, 0 deletions
diff --git a/fs/fs-writeback.c b/fs/fs-writeback.c
index 49bc1b8e8f1..f6c2155e002 100644
--- a/fs/fs-writeback.c
+++ b/fs/fs-writeback.c
@@ -1187,6 +1187,23 @@ void writeback_inodes_sb(struct super_block *sb)
EXPORT_SYMBOL(writeback_inodes_sb);
/**
+ * writeback_inodes_sb_if_idle - start writeback if none underway
+ * @sb: the superblock
+ *
+ * Invoke writeback_inodes_sb if no writeback is currently underway.
+ * Returns 1 if writeback was started, 0 if not.
+ */
+int writeback_inodes_sb_if_idle(struct super_block *sb)
+{
+ if (!writeback_in_progress(sb->s_bdi)) {
+ writeback_inodes_sb(sb);
+ return 1;
+ } else
+ return 0;
+}
+EXPORT_SYMBOL(writeback_inodes_sb_if_idle);
+
+/**
* sync_inodes_sb - sync sb inode pages
* @sb: the superblock
*
diff --git a/include/linux/writeback.h b/include/linux/writeback.h
index c18c008f4bb..76e8903cd20 100644
--- a/include/linux/writeback.h
+++ b/include/linux/writeback.h
@@ -70,6 +70,7 @@ struct writeback_control {
struct bdi_writeback;
int inode_wait(void *);
void writeback_inodes_sb(struct super_block *);
+int writeback_inodes_sb_if_idle(struct super_block *);
void sync_inodes_sb(struct super_block *);
void writeback_inodes_wbc(struct writeback_control *wbc);
long wb_do_writeback(struct bdi_writeback *wb, int force_wait);