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From:   trondmy@kernel.org
To:     linux-nfs@vger.kernel.org
Subject: [PATCH v4 01/21] NFS: Remove unnecessary inode locking in nfs_llseek_dir()
Date:   Sat,  7 Nov 2020 09:03:05 -0500
Message-Id: <20201107140325.281678-2-trondmy@kernel.org>
In-Reply-To: <20201107140325.281678-1-trondmy@kernel.org>
References: <20201107140325.281678-1-trondmy@kernel.org>
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From: Trond Myklebust <trond.myklebust@hammerspace.com>

Remove the contentious inode lock, and instead provide thread safety
using the file->f_lock spinlock.

Signed-off-by: Trond Myklebust <trond.myklebust@hammerspace.com>
---
 fs/nfs/dir.c | 9 ++++-----
 1 file changed, 4 insertions(+), 5 deletions(-)

diff --git a/fs/nfs/dir.c b/fs/nfs/dir.c
index cb52db9a0cfb..e56b1bd99537 100644
--- a/fs/nfs/dir.c
+++ b/fs/nfs/dir.c
@@ -955,7 +955,6 @@ static int nfs_readdir(struct file *file, struct dir_context *ctx)
 
 static loff_t nfs_llseek_dir(struct file *filp, loff_t offset, int whence)
 {
-	struct inode *inode = file_inode(filp);
 	struct nfs_open_dir_context *dir_ctx = filp->private_data;
 
 	dfprintk(FILE, "NFS: llseek dir(%pD2, %lld, %d)\n",
@@ -967,15 +966,15 @@ static loff_t nfs_llseek_dir(struct file *filp, loff_t offset, int whence)
 	case SEEK_SET:
 		if (offset < 0)
 			return -EINVAL;
-		inode_lock(inode);
+		spin_lock(&filp->f_lock);
 		break;
 	case SEEK_CUR:
 		if (offset == 0)
 			return filp->f_pos;
-		inode_lock(inode);
+		spin_lock(&filp->f_lock);
 		offset += filp->f_pos;
 		if (offset < 0) {
-			inode_unlock(inode);
+			spin_unlock(&filp->f_lock);
 			return -EINVAL;
 		}
 	}
@@ -987,7 +986,7 @@ static loff_t nfs_llseek_dir(struct file *filp, loff_t offset, int whence)
 			dir_ctx->dir_cookie = 0;
 		dir_ctx->duped = 0;
 	}
-	inode_unlock(inode);
+	spin_unlock(&filp->f_lock);
 	return offset;
 }
 
-- 
2.28.0