[PATCH 04/10] iomap: zeroing already holds invalidate_lock in iomap_file_buffered_write_punch_delalloc

[Christoph Hellwig <hch@xxxxxx>]

All callers of iomap_zero_range already hold invalidate_lock, so we can't
take it again in iomap_file_buffered_write_punch_delalloc.

Use the passed in flags argument to detect if we're called from a zeroing
operation and don't take the lock again in this case.

Signed-off-by: Christoph Hellwig <hch@xxxxxx>
---
 fs/iomap/buffered-io.c | 16 +++++++++++-----
 1 file changed, 11 insertions(+), 5 deletions(-)

diff --git a/fs/iomap/buffered-io.c b/fs/iomap/buffered-io.c
index 34de9f58794ad5..574ca413516443 100644
--- a/fs/iomap/buffered-io.c
+++ b/fs/iomap/buffered-io.c
@@ -1198,8 +1198,8 @@ static int iomap_write_delalloc_scan(struct inode *inode,
  * require sprinkling this code with magic "+ 1" and "- 1" arithmetic and expose
  * the code to subtle off-by-one bugs....
  */
-static int iomap_write_delalloc_release(struct inode *inode,
-		loff_t start_byte, loff_t end_byte, iomap_punch_t punch)
+static int iomap_write_delalloc_release(struct inode *inode, loff_t start_byte,
+		loff_t end_byte, unsigned flags, iomap_punch_t punch)
 {
 	loff_t punch_start_byte = start_byte;
 	loff_t scan_end_byte = min(i_size_read(inode), end_byte);
@@ -1210,8 +1210,13 @@ static int iomap_write_delalloc_release(struct inode *inode,
 	 * folios and dirtying them via ->page_mkwrite whilst we walk the
 	 * cache and perform delalloc extent removal. Failing to do this can
 	 * leave dirty pages with no space reservation in the cache.
+	 *
+	 * For zeroing operations the callers already hold invalidate_lock.
 	 */
-	filemap_invalidate_lock(inode->i_mapping);
+	if (flags & IOMAP_ZERO)
+		rwsem_assert_held_write(&inode->i_mapping->invalidate_lock);
+	else
+		filemap_invalidate_lock(inode->i_mapping);
 	while (start_byte < scan_end_byte) {
 		loff_t		data_end;
 
@@ -1264,7 +1269,8 @@ static int iomap_write_delalloc_release(struct inode *inode,
 		error = punch(inode, punch_start_byte,
 				end_byte - punch_start_byte);
 out_unlock:
-	filemap_invalidate_unlock(inode->i_mapping);
+	if (!(flags & IOMAP_ZERO))
+		filemap_invalidate_unlock(inode->i_mapping);
 	return error;
 }
 
@@ -1328,7 +1334,7 @@ int iomap_file_buffered_write_punch_delalloc(struct inode *inode,
 	if (start_byte >= end_byte)
 		return 0;
 
-	return iomap_write_delalloc_release(inode, start_byte, end_byte,
+	return iomap_write_delalloc_release(inode, start_byte, end_byte, flags,
 					punch);
 }
 EXPORT_SYMBOL_GPL(iomap_file_buffered_write_punch_delalloc);
-- 
2.43.0