f2fs: add nowait aio support

This patch adds nowait aio support[1].

Return EAGAIN if any of the following checks fail for direct I/O:
  - i_rwsem is not lockable
  - Blocks are not allocated at the write location

And xfstests generic/471 is passed.

 [1]: 6be96d "Introduce RWF_NOWAIT and FMODE_AIO_NOWAIT"

Signed-off-by: Hyunchul Lee <cheol.lee@lge.com>
Reviewed-by: Goldwyn Rodrigues <rgoldwyn@suse.com>
Reviewed-by: Chao Yu <yuchao0@huawei.com>
Signed-off-by: Jaegeuk Kim <jaegeuk@kernel.org>

1 files changed, 29 insertions, 6 deletions

diff --git a/fs/f2fs/file.c b/fs/f2fs/file.c
index 3072837744b9..c4c27e63daf1 100644
--- a/fs/f2fs/file.c
+++ b/fs/f2fs/file.c
@@ -480,6 +480,9 @@ static int f2fs_file_open(struct inode *inode, struct file *filp)
 
 	if (err)
 		return err;
+
+	filp->f_mode |= FMODE_NOWAIT;
+
 	return dquot_file_open(inode, filp);
 }
 
@@ -2896,7 +2899,15 @@ static ssize_t f2fs_file_write_iter(struct kiocb *iocb, struct iov_iter *from)
 	if (unlikely(f2fs_cp_error(F2FS_I_SB(inode))))
 		return -EIO;
 
-	inode_lock(inode);
+	if ((iocb->ki_flags & IOCB_NOWAIT) && !(iocb->ki_flags & IOCB_DIRECT))
+		return -EINVAL;
+
+	if (!inode_trylock(inode)) {
+		if (iocb->ki_flags & IOCB_NOWAIT)
+			return -EAGAIN;
+		inode_lock(inode);
+	}
+
 	ret = generic_write_checks(iocb, from);
 	if (ret > 0) {
 		int err;
@@ -2904,11 +2915,23 @@ static ssize_t f2fs_file_write_iter(struct kiocb *iocb, struct iov_iter *from)
 		if (iov_iter_fault_in_readable(from, iov_iter_count(from)))
 			set_inode_flag(inode, FI_NO_PREALLOC);
 
-		err = f2fs_preallocate_blocks(iocb, from);
-		if (err) {
-			clear_inode_flag(inode, FI_NO_PREALLOC);
-			inode_unlock(inode);
-			return err;
+		if ((iocb->ki_flags & IOCB_NOWAIT) &&
+			(iocb->ki_flags & IOCB_DIRECT)) {
+				if (!f2fs_overwrite_io(inode, iocb->ki_pos,
+						iov_iter_count(from)) ||
+					f2fs_has_inline_data(inode) ||
+					f2fs_force_buffered_io(inode, WRITE)) {
+						inode_unlock(inode);
+						return -EAGAIN;
+				}
+
+		} else {
+			err = f2fs_preallocate_blocks(iocb, from);
+			if (err) {
+				clear_inode_flag(inode, FI_NO_PREALLOC);
+				inode_unlock(inode);
+				return err;
+			}
 		}
 		blk_start_plug(&plug);
 		ret = __generic_file_write_iter(iocb, from);