[PATCH v3 05/12] btrfs: add btrfs_try_lock_ordered_range

Stefan Roesch
2022-09-12T19:28:16Z

From: Josef Bacik <josef@toxicpanda.com>

For IOCB_NOWAIT we're going to want to use try lock on the extent lock,
and simply bail if there's an ordered extent in the range because the
only choice there is to wait for the ordered extent to complete.

Signed-off-by: Josef Bacik <josef@toxicpanda.com>
Signed-off-by: Stefan Roesch <shr@fb.com>
---
fs/btrfs/ordered-data.c | 28 ++++++++++++++++++++++++++++
fs/btrfs/ordered-data.h | 1 +
2 files changed, 29 insertions(+)

diff --git a/fs/btrfs/ordered-data.c b/fs/btrfs/ordered-data.c
index 1952ac85222c..29c570f9a0ff 100644
--- a/fs/btrfs/ordered-data.c
+++ b/fs/btrfs/ordered-data.c
@@ -1041,6 +1041,34 @@ void btrfs_lock_and_flush_ordered_range(struct btrfs_inode *inode, u64 start,
}
}

+/*
+ * btrfs_try_lock_ordered_range - lock the passed range and ensure all pending
+ * ordered extents in it are run to completion in nowait mode.
+ *
+ * @inode: Inode whose ordered tree is to be searched
+ * @start: Beginning of range to flush
+ * @end: Last byte of range to lock
+ *
+ * This function returns true if btrfs_lock_ordered_range does not return any
+ * extents, otherwise false.
+ */
+bool btrfs_try_lock_ordered_range(struct btrfs_inode *inode, u64 start, u64 end)
+{
+ struct btrfs_ordered_extent *ordered;
+
+ if (!try_lock_extent(&inode->io_tree, start, end))
+ return false;
+
+ ordered = btrfs_lookup_ordered_range(inode, start, end - start + 1);
+ if (!ordered)
+ return true;
+
+ btrfs_put_ordered_extent(ordered);
+ unlock_extent(&inode->io_tree, start, end);
+ return false;
+}
+
+
static int clone_ordered_extent(struct btrfs_ordered_extent *ordered, u64 pos,
u64 len)
{
diff --git a/fs/btrfs/ordered-data.h b/fs/btrfs/ordered-data.h
index 87792f85e2c4..8edd4b2d3952 100644
--- a/fs/btrfs/ordered-data.h
+++ b/fs/btrfs/ordered-data.h
@@ -218,6 +218,7 @@ void btrfs_wait_ordered_roots(struct btrfs_fs_info *fs_info, u64 nr,
void btrfs_lock_and_flush_ordered_range(struct btrfs_inode *inode, u64 start,
u64 end,
struct extent_state **cached_state);
+bool btrfs_try_lock_ordered_range(struct btrfs_inode *inode, u64 start, u64 end);
int btrfs_split_ordered_extent(struct btrfs_ordered_extent *ordered, u64 pre,
u64 post);
int __init ordered_data_init(void);
--
2.30.2