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From: Dominique Martinet <[email protected]>
To: Alexander Viro <[email protected]>,
	Christian Brauner <[email protected]>,
	Jens Axboe <[email protected]>,
	Pavel Begunkov <[email protected]>,
	Stefan Roesch <[email protected]>
Cc: Clay Harris <[email protected]>,
	Dave Chinner <[email protected]>,
	[email protected], [email protected],
	[email protected],
	Dominique Martinet <[email protected]>
Subject: [PATCH v2 4/6] kernfs: implement readdir FMODE_NOWAIT
Date: Wed, 10 May 2023 19:52:52 +0900	[thread overview]
Message-ID: <[email protected]> (raw)
In-Reply-To: <[email protected]>

Since down_read can block, use the _trylock variant if NOWAIT variant
has been requested.
(can probably do a little bit better style-wise)

Signed-off-by: Dominique Martinet <[email protected]>
---
 fs/kernfs/dir.c | 20 +++++++++++++++++++-
 1 file changed, 19 insertions(+), 1 deletion(-)

diff --git a/fs/kernfs/dir.c b/fs/kernfs/dir.c
index 45b6919903e6..5a5b3e7881bf 100644
--- a/fs/kernfs/dir.c
+++ b/fs/kernfs/dir.c
@@ -1824,7 +1824,12 @@ static int kernfs_fop_readdir(struct file *file, struct dir_context *ctx)
 		return 0;
 
 	root = kernfs_root(parent);
-	down_read(&root->kernfs_rwsem);
+	if (ctx->flags & DIR_CONTEXT_F_NOWAIT) {
+		if (!down_read_trylock(&root->kernfs_rwsem))
+			return -EAGAIN;
+	} else {
+		down_read(&root->kernfs_rwsem);
+	}
 
 	if (kernfs_ns_enabled(parent))
 		ns = kernfs_info(dentry->d_sb)->ns;
@@ -1845,6 +1850,12 @@ static int kernfs_fop_readdir(struct file *file, struct dir_context *ctx)
 		if (!dir_emit(ctx, name, len, ino, type))
 			return 0;
 		down_read(&root->kernfs_rwsem);
+		if (ctx->flags & DIR_CONTEXT_F_NOWAIT) {
+			if (!down_read_trylock(&root->kernfs_rwsem))
+				return 0;
+		} else {
+			down_read(&root->kernfs_rwsem);
+		}
 	}
 	up_read(&root->kernfs_rwsem);
 	file->private_data = NULL;
@@ -1852,7 +1863,14 @@ static int kernfs_fop_readdir(struct file *file, struct dir_context *ctx)
 	return 0;
 }
 
+static int kernfs_fop_dir_open(struct inode *inode, struct file *file)
+{
+	file->f_mode |= FMODE_NOWAIT;
+	return 0;
+}
+
 const struct file_operations kernfs_dir_fops = {
+	.open		= kernfs_fop_dir_open,
 	.read		= generic_read_dir,
 	.iterate_shared	= kernfs_fop_readdir,
 	.release	= kernfs_dir_fop_release,

-- 
2.39.2


  parent reply	other threads:[~2023-05-10 10:53 UTC|newest]

Thread overview: 20+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2023-05-10 10:52 [PATCH v2 0/6] io_uring: add getdents support, take 2 Dominique Martinet
2023-05-10 10:52 ` [PATCH v2 1/6] fs: split off vfs_getdents function of getdents64 syscall Dominique Martinet
2023-05-23 15:39   ` Christian Brauner
2023-05-23 21:13     ` Dominique Martinet
2023-05-10 10:52 ` [PATCH v2 2/6] vfs_getdents/struct dir_context: add flags field Dominique Martinet
2023-05-10 10:52 ` [PATCH v2 3/6] io_uring: add support for getdents Dominique Martinet
2023-05-10 10:52 ` Dominique Martinet [this message]
2023-05-11 10:55   ` [PATCH v2 4/6] kernfs: implement readdir FMODE_NOWAIT Dan Carpenter
2023-05-11 11:03     ` Dominique Martinet
2023-05-10 10:52 ` [PATCH v2 5/6] libfs: set FMODE_NOWAIT on dir open Dominique Martinet
2023-05-10 10:52 ` [PATCH v2 6/6] RFC: io_uring getdents: test returning an EOF flag in CQE Dominique Martinet
2023-05-23 14:30   ` Christian Brauner
2023-05-23 21:05     ` Dominique Martinet
2023-05-24 13:52       ` [PATCH v2 1/6] fs: split off vfs_getdents function of getdents64 syscall Christian Brauner
2023-05-24 21:36         ` Dominique Martinet
2023-05-25  9:22           ` Christian Brauner
2023-05-25 11:00             ` Dominique Martinet
2023-05-25 12:33               ` Christian Brauner
2023-07-11  8:17               ` Hao Xu
2023-07-11  8:24                 ` Dominique Martinet

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