[PATCH 02/10] xfs: make xfs_file_aio_write_checks IOCB_NOWAIT-aware

Christoph Hellwig
2021-01-12T16:27:53Z

Ensure we don't block on the iolock, or waiting for I/O in
xfs_file_aio_write_checks if the caller asked to avoid that.

Fixes: 29a5d29ec181 ("xfs: nowait aio support")
Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Brian Foster <bfoster@redhat.com>
---
fs/xfs/xfs_file.c | 25 +++++++++++++++++++++----
1 file changed, 21 insertions(+), 4 deletions(-)

diff --git a/fs/xfs/xfs_file.c b/fs/xfs/xfs_file.c
index c441cddfa4acbc..fb4e6f2852bb8b 100644
--- a/fs/xfs/xfs_file.c
+++ b/fs/xfs/xfs_file.c
@@ -335,7 +335,14 @@ xfs_file_aio_write_checks(
if (error <= 0)
return error;

- error = xfs_break_layouts(inode, iolock, BREAK_WRITE);
+ if (iocb->ki_flags & IOCB_NOWAIT) {
+ error = break_layout(inode, false);
+ if (error == -EWOULDBLOCK)
+ error = -EAGAIN;
+ } else {
+ error = xfs_break_layouts(inode, iolock, BREAK_WRITE);
+ }
+
if (error)
return error;

@@ -346,7 +353,11 @@ xfs_file_aio_write_checks(
if (*iolock == XFS_IOLOCK_SHARED && !IS_NOSEC(inode)) {
xfs_iunlock(ip, *iolock);
*iolock = XFS_IOLOCK_EXCL;
- xfs_ilock(ip, *iolock);
+ error = xfs_ilock_iocb(iocb, *iolock);
+ if (error) {
+ *iolock = 0;
+ return error;
+ }
goto restart;
}
/*
@@ -368,6 +379,10 @@ xfs_file_aio_write_checks(
isize = i_size_read(inode);
if (iocb->ki_pos > isize) {
spin_unlock(&ip->i_flags_lock);
+
+ if (iocb->ki_flags & IOCB_NOWAIT)
+ return -EAGAIN;
+
if (!drained_dio) {
if (*iolock == XFS_IOLOCK_SHARED) {
xfs_iunlock(ip, *iolock);
@@ -593,7 +608,8 @@ xfs_file_dio_aio_write(
&xfs_dio_write_ops,
is_sync_kiocb(iocb) || unaligned_io);
out:
- xfs_iunlock(ip, iolock);
+ if (iolock)
+ xfs_iunlock(ip, iolock);

/*
* No fallback to buffered IO after short writes for XFS, direct I/O
@@ -632,7 +648,8 @@ xfs_file_dax_write(
error = xfs_setfilesize(ip, pos, ret);
}
out:
- xfs_iunlock(ip, iolock);
+ if (iolock)
+ xfs_iunlock(ip, iolock);
if (error)
return error;

--
2.29.2