On 11/23/21 18:10, Stefan Roesch wrote:
This adds the use_fpos parameter to the iterate_dir function.
If use_fpos is true it uses the file position in the file
structure (existing behavior). If use_fpos is false, it uses
the pos in the context structure.
This change is required to support getdents in io_uring.
Signed-off-by: Stefan Roesch <shr@xxxxxx>
---
fs/exportfs/expfs.c | 2 +-
fs/nfsd/nfs4recover.c | 2 +-
fs/nfsd/vfs.c | 2 +-
fs/overlayfs/readdir.c | 6 +++---
fs/readdir.c | 28 ++++++++++++++++++++--------
include/linux/fs.h | 2 +-
6 files changed, 27 insertions(+), 15 deletions(-)
[...]
diff --git a/fs/readdir.c b/fs/readdir.c
index 09e8ed7d4161..8ea5b5f45a78 100644
--- a/fs/readdir.c
+++ b/fs/readdir.c
@@ -21,6 +21,7 @@
#include <linux/unistd.h>
#include <linux/compat.h>
#include <linux/uaccess.h>
+#include "internal.h"
#include <asm/unaligned.h>
@@ -36,8 +37,14 @@
unsafe_copy_to_user(dst, src, len, label); \
} while (0)
-
-int iterate_dir(struct file *file, struct dir_context *ctx)
+/**
+ * iterate_dir - iterate over directory
+ * @file : pointer to file struct of directory
+ * @ctx : pointer to directory ctx structure
+ * @use_fpos: true : use file offset
+ * false: use pos in ctx structure
+ */
+int iterate_dir(struct file *file, struct dir_context *ctx, bool use_fpos)
{
struct inode *inode = file_inode(file);
bool shared = false;
@@ -60,12 +67,17 @@ int iterate_dir(struct file *file, struct dir_context *ctx)
res = -ENOENT;
if (!IS_DEADDIR(inode)) {
- ctx->pos = file->f_pos;
+ if (use_fpos)
+ ctx->pos = file->f_pos;
One more thing I haven't noticed before, should pos be sanitised
somehow if passed from the userspace? Do filesystems handle it
well?
+
if (shared)
res = file->f_op->iterate_shared(file, ctx);
else
res = file->f_op->iterate(file, ctx);
- file->f_pos = ctx->pos;
+
+ if (use_fpos)
+ file->f_pos = ctx->pos;
+
fsnotify_access(file);
file_accessed(file);
}
--
Pavel Begunkov
