[PATCH v1 1/3] fs: add parameter use_fpos to iterate_dir function

[Stefan Roesch <shr@fb.com>]

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@fb.com>
---
 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/exportfs/expfs.c b/fs/exportfs/expfs.c
index 0106eba46d5a..0f303356f907 100644
--- a/fs/exportfs/expfs.c
+++ b/fs/exportfs/expfs.c
@@ -323,7 +323,7 @@ static int get_name(const struct path *path, char *name, struct dentry *child)
 	while (1) {
 		int old_seq = buffer.sequence;
 
-		error = iterate_dir(file, &buffer.ctx);
+		error = iterate_dir(file, &buffer.ctx, true);
 		if (buffer.found) {
 			error = 0;
 			break;
diff --git a/fs/nfsd/nfs4recover.c b/fs/nfsd/nfs4recover.c
index 6fedc49726bf..013b1a3530c9 100644
--- a/fs/nfsd/nfs4recover.c
+++ b/fs/nfsd/nfs4recover.c
@@ -307,7 +307,7 @@ nfsd4_list_rec_dir(recdir_func *f, struct nfsd_net *nn)
 		return status;
 	}
 
-	status = iterate_dir(nn->rec_file, &ctx.ctx);
+	status = iterate_dir(nn->rec_file, &ctx.ctx, true);
 	inode_lock_nested(d_inode(dir), I_MUTEX_PARENT);
 
 	list_for_each_entry_safe(entry, tmp, &ctx.names, list) {
diff --git a/fs/nfsd/vfs.c b/fs/nfsd/vfs.c
index c99857689e2c..cd7a7d783fa7 100644
--- a/fs/nfsd/vfs.c
+++ b/fs/nfsd/vfs.c
@@ -1980,7 +1980,7 @@ static __be32 nfsd_buffered_readdir(struct file *file, struct svc_fh *fhp,
 		buf.used = 0;
 		buf.full = 0;
 
-		host_err = iterate_dir(file, &buf.ctx);
+		host_err = iterate_dir(file, &buf.ctx, true);
 		if (buf.full)
 			host_err = 0;
 
diff --git a/fs/overlayfs/readdir.c b/fs/overlayfs/readdir.c
index 150fdf3bc68d..089150315942 100644
--- a/fs/overlayfs/readdir.c
+++ b/fs/overlayfs/readdir.c
@@ -306,7 +306,7 @@ static inline int ovl_dir_read(struct path *realpath,
 	do {
 		rdd->count = 0;
 		rdd->err = 0;
-		err = iterate_dir(realfile, &rdd->ctx);
+		err = iterate_dir(realfile, &rdd->ctx, true);
 		if (err >= 0)
 			err = rdd->err;
 	} while (!err && rdd->count);
@@ -722,7 +722,7 @@ static int ovl_iterate_real(struct file *file, struct dir_context *ctx)
 			return PTR_ERR(rdt.cache);
 	}
 
-	err = iterate_dir(od->realfile, &rdt.ctx);
+	err = iterate_dir(od->realfile, &rdt.ctx, true);
 	ctx->pos = rdt.ctx.pos;
 
 	return err;
@@ -753,7 +753,7 @@ static int ovl_iterate(struct file *file, struct dir_context *ctx)
 		      OVL_TYPE_MERGE(ovl_path_type(dentry->d_parent))))) {
 			err = ovl_iterate_real(file, ctx);
 		} else {
-			err = iterate_dir(od->realfile, ctx);
+			err = iterate_dir(od->realfile, ctx, true);
 		}
 		goto out;
 	}
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;
+
 		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);
 	}
@@ -190,7 +202,7 @@ SYSCALL_DEFINE3(old_readdir, unsigned int, fd,
 	if (!f.file)
 		return -EBADF;
 
-	error = iterate_dir(f.file, &buf.ctx);
+	error = iterate_dir(f.file, &buf.ctx, true);
 	if (buf.result)
 		error = buf.result;
 
@@ -283,7 +295,7 @@ SYSCALL_DEFINE3(getdents, unsigned int, fd,
 	if (!f.file)
 		return -EBADF;
 
-	error = iterate_dir(f.file, &buf.ctx);
+	error = iterate_dir(f.file, &buf.ctx, true);
 	if (error >= 0)
 		error = buf.error;
 	if (buf.prev_reclen) {
@@ -448,7 +460,7 @@ COMPAT_SYSCALL_DEFINE3(old_readdir, unsigned int, fd,
 	if (!f.file)
 		return -EBADF;
 
-	error = iterate_dir(f.file, &buf.ctx);
+	error = iterate_dir(f.file, &buf.ctx, true);
 	if (buf.result)
 		error = buf.result;
 
@@ -534,7 +546,7 @@ COMPAT_SYSCALL_DEFINE3(getdents, unsigned int, fd,
 	if (!f.file)
 		return -EBADF;
 
-	error = iterate_dir(f.file, &buf.ctx);
+	error = iterate_dir(f.file, &buf.ctx, true);
 	if (error >= 0)
 		error = buf.error;
 	if (buf.prev_reclen) {
diff --git a/include/linux/fs.h b/include/linux/fs.h
index 1cb616fc1105..ba4f49c4ac41 100644
--- a/include/linux/fs.h
+++ b/include/linux/fs.h
@@ -3343,7 +3343,7 @@ const char *simple_get_link(struct dentry *, struct inode *,
 			    struct delayed_call *);
 extern const struct inode_operations simple_symlink_inode_operations;
 
-extern int iterate_dir(struct file *, struct dir_context *);
+extern int iterate_dir(struct file *file, struct dir_context *ctx, bool use_fpos);
 
 int vfs_fstatat(int dfd, const char __user *filename, struct kstat *stat,
 		int flags);
-- 
2.30.2