From: Goldwyn Rodrigues <rgoldwyn@xxxxxxxx>
If direct writes are called with O_DIRECT | O_DSYNC, it will result in a
deadlock because iomap_dio_rw() is called under i_rwsem which calls
iomap_dio_complete()
generic_write_sync()
btrfs_sync_file().
btrfs_sync_file() requires i_rwsem, so call __iomap_dio_rw() with the
i_rwsem locked, and call iomap_dio_complete() after unlocking i_rwsem.
Signed-off-by: Goldwyn Rodrigues <rgoldwyn@xxxxxxxx>
---
fs/btrfs/file.c | 24 +++++++++++-------------
1 file changed, 11 insertions(+), 13 deletions(-)
diff --git a/fs/btrfs/file.c b/fs/btrfs/file.c
index 193af84f5405..9c7a2d4b4148 100644
--- a/fs/btrfs/file.c
+++ b/fs/btrfs/file.c
@@ -1981,6 +1981,7 @@ static ssize_t btrfs_direct_write(struct kiocb *iocb, struct iov_iter *from)
loff_t endbyte;
int err;
int ilock_flags = 0;
+ struct iomap_dio *dio = NULL;
if (iocb->ki_flags & IOCB_NOWAIT)
ilock_flags |= BTRFS_ILOCK_TRY;
@@ -2022,22 +2023,19 @@ static ssize_t btrfs_direct_write(struct kiocb *iocb, struct iov_iter *from)
goto buffered;
}
- /*
- * We have are actually a sync iocb, so we need our fancy endio to know
- * if we need to sync.
- */
- if (current->journal_info)
- written = iomap_dio_rw(iocb, from, &btrfs_dio_iomap_ops,
- &btrfs_sync_dops, is_sync_kiocb(iocb));
- else
- written = iomap_dio_rw(iocb, from, &btrfs_dio_iomap_ops,
- &btrfs_dio_ops, is_sync_kiocb(iocb));
-
- if (written == -ENOTBLK)
- written = 0;
+ dio = __iomap_dio_rw(iocb, from, &btrfs_dio_iomap_ops,
+ &btrfs_dio_ops, is_sync_kiocb(iocb));
btrfs_inode_unlock(inode, ilock_flags);
+ if (IS_ERR_OR_NULL(dio)) {
+ err = PTR_ERR_OR_ZERO(dio);
+ if (err < 0 && err != -ENOTBLK)
+ goto out;
+ } else {
+ written = iomap_dio_complete(dio);
+ }
+
if (written < 0 || !iov_iter_count(from)) {
err = written;
goto out;
--
2.26.2
