linux-ext4 - [PATCH 7/8] nowait aio: xfs

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Date:   Tue, 28 Feb 2017 17:36:09 -0600
From:   Goldwyn Rodrigues <rgoldwyn@...e.de>
To:     jack@...e.com
Cc:     hch@...radead.org, linux-fsdevel@...r.kernel.org,
        linux-block@...r.kernel.org, linux-btrfs@...r.kernel.org,
        linux-ext4@...r.kernel.org, linux-xfs@...r.kernel.org,
        Goldwyn Rodrigues <rgoldwyn@...e.com>
Subject: [PATCH 7/8] nowait aio: xfs

From: Goldwyn Rodrigues <rgoldwyn@...e.com>

If IOCB_NOWAIT is set, bail if the i_rwsem is not lockable
immediately.

IF IOMAP_NOWAIT is set, return EAGAIN in xfs_file_iomap_begin
if it needs allocation either due to file extending, writing to a hole,
or COW.

Signed-off-by: Goldwyn Rodrigues <rgoldwyn@...e.com>
---
 fs/xfs/xfs_file.c  | 9 +++++++--
 fs/xfs/xfs_iomap.c | 9 +++++++++
 2 files changed, 16 insertions(+), 2 deletions(-)

diff --git a/fs/xfs/xfs_file.c b/fs/xfs/xfs_file.c
index bbb9eb6..7e16a83 100644
--- a/fs/xfs/xfs_file.c
+++ b/fs/xfs/xfs_file.c
@@ -528,12 +528,17 @@ xfs_file_dio_aio_write(
 	    ((iocb->ki_pos + count) & mp->m_blockmask)) {
 		unaligned_io = 1;
 		iolock = XFS_IOLOCK_EXCL;
+		if (iocb->ki_flags & IOCB_NOWAIT)
+			return -EAGAIN;
 	} else {
 		iolock = XFS_IOLOCK_SHARED;
 	}
 
-	xfs_ilock(ip, iolock);
-
+	if (!xfs_ilock_nowait(ip, iolock)) {
+		if (iocb->ki_flags & IOCB_NOWAIT)
+			return -EAGAIN;
+		xfs_ilock(ip, iolock);
+	}
 	ret = xfs_file_aio_write_checks(iocb, from, &iolock);
 	if (ret)
 		goto out;
diff --git a/fs/xfs/xfs_iomap.c b/fs/xfs/xfs_iomap.c
index 1aa3abd..84f981a 100644
--- a/fs/xfs/xfs_iomap.c
+++ b/fs/xfs/xfs_iomap.c
@@ -1020,6 +1020,11 @@ xfs_file_iomap_begin(
 	if ((flags & IOMAP_REPORT) ||
 	    (xfs_is_reflink_inode(ip) &&
 	     (flags & IOMAP_WRITE) && (flags & IOMAP_DIRECT))) {
+		/* Allocations due to reflinks */
+		if ((flags & IOMAP_NOWAIT) && !(flags & IOMAP_REPORT)) {
+			error = -EAGAIN;
+			goto out_unlock;
+		}
 		/* Trim the mapping to the nearest shared extent boundary. */
 		error = xfs_reflink_trim_around_shared(ip, &imap, &shared,
 				&trimmed);
@@ -1049,6 +1054,10 @@ xfs_file_iomap_begin(
 	}
 
 	if ((flags & IOMAP_WRITE) && imap_needs_alloc(inode, &imap, nimaps)) {
+		if (flags & IOMAP_NOWAIT) {
+			error = -EAGAIN;
+			goto out_unlock;
+		}
 		/*
 		 * We cap the maximum length we map here to MAX_WRITEBACK_PAGES
 		 * pages to keep the chunks of work done where somewhat symmetric
-- 
2.10.2