[RFC PATCH v4 16/17] xfs: Add async buffered write support

[Stefan Roesch <shr@fb.com>]

This adds the async buffered write support to XFS. For async buffered
write requests, the request will return -EAGAIN if the ilock cannot be
obtained immediately.

This splits off a new helper xfs_ilock_inode from the existing helper
xfs_ilock_iocb so it can be used for this function. The exising helper
cannot be used as it hardcoded the inode to be used.

Signed-off-by: Stefan Roesch <shr@fb.com>
---
 fs/xfs/xfs_file.c | 32 +++++++++++++++-----------------
 1 file changed, 15 insertions(+), 17 deletions(-)

diff --git a/fs/xfs/xfs_file.c b/fs/xfs/xfs_file.c
index 793918c83755..ad3175b7d366 100644
--- a/fs/xfs/xfs_file.c
+++ b/fs/xfs/xfs_file.c
@@ -190,14 +190,13 @@ xfs_file_fsync(
 	return error;
 }
 
-static int
-xfs_ilock_iocb(
-	struct kiocb		*iocb,
+static inline int
+xfs_ilock_xfs_inode(
+	struct xfs_inode	*ip,
+	int			flags,
 	unsigned int		lock_mode)
 {
-	struct xfs_inode	*ip = XFS_I(file_inode(iocb->ki_filp));
-
-	if (iocb->ki_flags & IOCB_NOWAIT) {
+	if (flags & IOCB_NOWAIT) {
 		if (!xfs_ilock_nowait(ip, lock_mode))
 			return -EAGAIN;
 	} else {
@@ -222,7 +221,7 @@ xfs_file_dio_read(
 
 	file_accessed(iocb->ki_filp);
 
-	ret = xfs_ilock_iocb(iocb, XFS_IOLOCK_SHARED);
+	ret = xfs_ilock_xfs_inode(ip, iocb->ki_flags, XFS_IOLOCK_SHARED);
 	if (ret)
 		return ret;
 	ret = iomap_dio_rw(iocb, to, &xfs_read_iomap_ops, NULL, 0, 0);
@@ -244,7 +243,7 @@ xfs_file_dax_read(
 	if (!iov_iter_count(to))
 		return 0; /* skip atime */
 
-	ret = xfs_ilock_iocb(iocb, XFS_IOLOCK_SHARED);
+	ret = xfs_ilock_xfs_inode(ip, iocb->ki_flags, XFS_IOLOCK_SHARED);
 	if (ret)
 		return ret;
 	ret = dax_iomap_rw(iocb, to, &xfs_read_iomap_ops);
@@ -264,7 +263,7 @@ xfs_file_buffered_read(
 
 	trace_xfs_file_buffered_read(iocb, to);
 
-	ret = xfs_ilock_iocb(iocb, XFS_IOLOCK_SHARED);
+	ret = xfs_ilock_xfs_inode(ip, iocb->ki_flags, XFS_IOLOCK_SHARED);
 	if (ret)
 		return ret;
 	ret = generic_file_read_iter(iocb, to);
@@ -343,7 +342,7 @@ xfs_file_write_checks(
 	if (*iolock == XFS_IOLOCK_SHARED && !IS_NOSEC(inode)) {
 		xfs_iunlock(ip, *iolock);
 		*iolock = XFS_IOLOCK_EXCL;
-		error = xfs_ilock_iocb(iocb, *iolock);
+		error = xfs_ilock_xfs_inode(ip, iocb->ki_flags, *iolock);
 		if (error) {
 			*iolock = 0;
 			return error;
@@ -516,7 +515,7 @@ xfs_file_dio_write_aligned(
 	int			iolock = XFS_IOLOCK_SHARED;
 	ssize_t			ret;
 
-	ret = xfs_ilock_iocb(iocb, iolock);
+	ret = xfs_ilock_xfs_inode(ip, iocb->ki_flags, iolock);
 	if (ret)
 		return ret;
 	ret = xfs_file_write_checks(iocb, from, &iolock);
@@ -583,7 +582,7 @@ xfs_file_dio_write_unaligned(
 		flags = IOMAP_DIO_FORCE_WAIT;
 	}
 
-	ret = xfs_ilock_iocb(iocb, iolock);
+	ret = xfs_ilock_xfs_inode(ip, iocb->ki_flags, iolock);
 	if (ret)
 		return ret;
 
@@ -659,7 +658,7 @@ xfs_file_dax_write(
 	ssize_t			ret, error = 0;
 	loff_t			pos;
 
-	ret = xfs_ilock_iocb(iocb, iolock);
+	ret = xfs_ilock_xfs_inode(ip, iocb->ki_flags, iolock);
 	if (ret)
 		return ret;
 	ret = xfs_file_write_checks(iocb, from, &iolock);
@@ -702,12 +701,11 @@ xfs_file_buffered_write(
 	bool			cleared_space = false;
 	int			iolock;
 
-	if (iocb->ki_flags & IOCB_NOWAIT)
-		return -EOPNOTSUPP;
-
 write_retry:
 	iolock = XFS_IOLOCK_EXCL;
-	xfs_ilock(ip, iolock);
+	ret = xfs_ilock_xfs_inode(ip, iocb->ki_flags, iolock);
+	if (ret)
+		return ret;
 
 	ret = xfs_file_write_checks(iocb, from, &iolock);
 	if (ret)
-- 
2.30.2