[PATCH 07/14] btrfs: Move FS error state bit early during write

From: Goldwyn Rodrigues <rgoldwyn@suse.de>
To: linux-fsdevel@vger.kernel.org
Cc: linux-btrfs@vger.kernel.org, david@fromorbit.com, hch@lst.de,
	johannes.thumshirn@wdc.com, dsterba@suse.com,
	darrick.wong@oracle.com, josef@toxicpanda.com,
	Goldwyn Rodrigues <rgoldwyn@suse.com>
Subject: [PATCH 07/14] btrfs: Move FS error state bit early during write
Date: Thu, 24 Sep 2020 11:39:14 -0500	[thread overview]
Message-ID: <20200924163922.2547-8-rgoldwyn@suse.de> (raw)
In-Reply-To: <20200924163922.2547-1-rgoldwyn@suse.de>

From: Goldwyn Rodrigues <rgoldwyn@suse.com>

fs_info->fs_state is a filesystem bit check as opposed to inode
and can be performed before we begin with write checks. This eliminates
inode lock/unlock in case the error bit is set.

Reviewed-by: Josef Bacik <josef@toxicpanda.com>
Signed-off-by: Goldwyn Rodrigues <rgoldwyn@suse.com>
---
 fs/btrfs/file.c | 20 ++++++++------------
 1 file changed, 8 insertions(+), 12 deletions(-)

diff --git a/fs/btrfs/file.c b/fs/btrfs/file.c
index 4c40a2742aab..f7e96754d4c9 100644
--- a/fs/btrfs/file.c
+++ b/fs/btrfs/file.c
@@ -1981,6 +1981,14 @@ static ssize_t btrfs_file_write_iter(struct kiocb *iocb,
 	size_t count;
 	loff_t oldsize;
 
+	/*
+	 * If BTRFS flips readonly due to some impossible error,
+	 * although we have opened a file as writable, we have
+	 * to stop this write operation to ensure FS consistency.
+	 */
+	if (test_bit(BTRFS_FS_STATE_ERROR, &fs_info->fs_state))
+		return -EROFS;
+
 	if (!(iocb->ki_flags & IOCB_DIRECT) &&
 	    (iocb->ki_flags & IOCB_NOWAIT))
 		return -EOPNOTSUPP;
@@ -2030,18 +2038,6 @@ static ssize_t btrfs_file_write_iter(struct kiocb *iocb,
 		goto out;
 	}
 
-	/*
-	 * If BTRFS flips readonly due to some impossible error
-	 * (fs_info->fs_state now has BTRFS_SUPER_FLAG_ERROR),
-	 * although we have opened a file as writable, we have
-	 * to stop this write operation to ensure FS consistency.
-	 */
-	if (test_bit(BTRFS_FS_STATE_ERROR, &fs_info->fs_state)) {
-		inode_unlock(inode);
-		err = -EROFS;
-		goto out;
-	}
-
 	/*
 	 * We reserve space for updating the inode when we reserve space for the
 	 * extent we are going to write, so we will enospc out there.  We don't
-- 
2.26.2

