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From: Lennert Buytenhek <[email protected]>
To: Jens Axboe <[email protected]>, Al Viro <[email protected]>,
	[email protected], [email protected],
	[email protected]
Cc: David Laight <[email protected]>,
	Matthew Wilcox <[email protected]>
Subject: [PATCH v3 1/2] readdir: split the core of getdents64(2) out into vfs_getdents()
Date: Thu, 18 Feb 2021 14:27:21 +0200	[thread overview]
Message-ID: <[email protected]> (raw)
In-Reply-To: <[email protected]>

So that IORING_OP_GETDENTS may use it, split out the core of the
getdents64(2) syscall into a helper function, vfs_getdents().

vfs_getdents() calls into filesystems' ->iterate{,_shared}() which
expect serialization on struct file, which means that callers of
vfs_getdents() are responsible for either using fdget_pos() or
performing the equivalent serialization by hand.

Cc: Al Viro <[email protected]>
Signed-off-by: Lennert Buytenhek <[email protected]>
---
 fs/readdir.c       | 25 +++++++++++++++++--------
 include/linux/fs.h |  4 ++++
 2 files changed, 21 insertions(+), 8 deletions(-)

diff --git a/fs/readdir.c b/fs/readdir.c
index 19434b3c982c..f52167c1eb61 100644
--- a/fs/readdir.c
+++ b/fs/readdir.c
@@ -348,10 +348,9 @@ static int filldir64(struct dir_context *ctx, const char *name, int namlen,
 	return -EFAULT;
 }
 
-SYSCALL_DEFINE3(getdents64, unsigned int, fd,
-		struct linux_dirent64 __user *, dirent, unsigned int, count)
+int vfs_getdents(struct file *file, struct linux_dirent64 __user *dirent,
+		 unsigned int count)
 {
-	struct fd f;
 	struct getdents_callback64 buf = {
 		.ctx.actor = filldir64,
 		.count = count,
@@ -359,11 +358,7 @@ SYSCALL_DEFINE3(getdents64, unsigned int, fd,
 	};
 	int error;
 
-	f = fdget_pos(fd);
-	if (!f.file)
-		return -EBADF;
-
-	error = iterate_dir(f.file, &buf.ctx);
+	error = iterate_dir(file, &buf.ctx);
 	if (error >= 0)
 		error = buf.error;
 	if (buf.prev_reclen) {
@@ -376,6 +371,20 @@ SYSCALL_DEFINE3(getdents64, unsigned int, fd,
 		else
 			error = count - buf.count;
 	}
+	return error;
+}
+
+SYSCALL_DEFINE3(getdents64, unsigned int, fd,
+		struct linux_dirent64 __user *, dirent, unsigned int, count)
+{
+	struct fd f;
+	int error;
+
+	f = fdget_pos(fd);
+	if (!f.file)
+		return -EBADF;
+
+	error = vfs_getdents(f.file, dirent, count);
 	fdput_pos(f);
 	return error;
 }
diff --git a/include/linux/fs.h b/include/linux/fs.h
index fd47deea7c17..114885d3f6c4 100644
--- a/include/linux/fs.h
+++ b/include/linux/fs.h
@@ -3109,6 +3109,10 @@ extern const struct inode_operations simple_symlink_inode_operations;
 
 extern int iterate_dir(struct file *, struct dir_context *);
 
+struct linux_dirent64;
+int vfs_getdents(struct file *file, struct linux_dirent64 __user *dirent,
+		 unsigned int count);
+
 int vfs_fstatat(int dfd, const char __user *filename, struct kstat *stat,
 		int flags);
 int vfs_fstat(int fd, struct kstat *stat);
-- 
2.29.2

  reply	other threads:[~2021-02-18 15:41 UTC|newest]

Thread overview: 13+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-02-18 12:26 [PATCH v3 0/2] io_uring: add support for IORING_OP_GETDENTS Lennert Buytenhek
2021-02-18 12:27 ` Lennert Buytenhek [this message]
2021-02-18 12:27 ` [PATCH v3 2/2] " Lennert Buytenhek
2021-02-19 12:05   ` Pavel Begunkov
2021-02-19 12:10     ` Pavel Begunkov
2021-02-19 18:06     ` Lennert Buytenhek
2021-02-19 12:34   ` Matthew Wilcox
2021-02-19 18:07     ` Lennert Buytenhek
2021-02-19 18:59       ` Lennert Buytenhek
2021-02-20 17:44 ` [PATCH v3 0/2] " David Laight
2021-02-20 18:29   ` Jens Axboe
2021-02-21 19:38     ` David Laight
2021-02-21 21:12       ` Jens Axboe

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