lkml.org 
[lkml]   [2021]   [Feb]   [18]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
Patch in this message
/
Date
From
Subject[PATCH v3 1/2] readdir: split the core of getdents64(2) out into vfs_getdents()
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 <viro@zeniv.linux.org.uk>
Signed-off-by: Lennert Buytenhek <buytenh@wantstofly.org>
---
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
\
 
 \ /
  Last update: 2021-02-18 15:32    [W:0.108 / U:0.548 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site