xfs: make xfs_file_aio_write_checks IOCB_NOWAIT-aware

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: Dave Chinner <dchinner@redhat.com>
Reviewed-by: Brian Foster <bfoster@redhat.com>
Reviewed-by: Darrick J. Wong <djwong@kernel.org>
Signed-off-by: Darrick J. Wong <djwong@kernel.org>

diff --git a/fs/xfs/xfs_file.c b/fs/xfs/xfs_file.c
index 13ca049c44fd76f9c764d2a5054445ce2dc6fff6..df6a9a51b2d80b7e357cdd88c1e540e62f87304f 100644 (file)
--- a/fs/xfs/xfs_file.c
+++ b/fs/xfs/xfs_file.c
@@ -334,7 +334,14 @@ restart:
        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;
 
@@ -345,7 +352,11 @@ restart:
        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;
        }
        /*
@@ -367,6 +378,10 @@ restart:
        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);
@@ -592,7 +607,8 @@ xfs_file_dio_aio_write(
                           &xfs_dio_write_ops,
                           unaligned_io ? IOMAP_DIO_FORCE_WAIT : 0);
 out:
-       xfs_iunlock(ip, iolock);
+       if (iolock)
+               xfs_iunlock(ip, iolock);
 
        /*
         * No fallback to buffered IO after short writes for XFS, direct I/O
@@ -631,7 +647,8 @@ 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;