linux-kernel - [PATCH] erofs: update ctx->pos for every emitted dirent

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Date:   Fri, 27 May 2022 15:25:36 +0800
From:   Hongnan Li <hongnan.li@...ux.alibaba.com>
To:     linux-erofs@...ts.ozlabs.org, xiang@...nel.org, chao@...nel.org
Cc:     linux-kernel@...r.kernel.org
Subject: [PATCH] erofs: update ctx->pos for every emitted dirent

erofs_readdir update ctx->pos after filling a batch of dentries
and it may cause dir/files duplication for NFS readdirplus which
depends on ctx->pos to fill dir correctly. So update ctx->pos for
every emitted dirent in erofs_fill_dentries to fix it.

Fixes: 3e917cc305c6 ("erofs: make filesystem exportable")
Signed-off-by: Hongnan Li <hongnan.li@...ux.alibaba.com>
---
 fs/erofs/dir.c | 13 ++++++-------
 1 file changed, 6 insertions(+), 7 deletions(-)

diff --git a/fs/erofs/dir.c b/fs/erofs/dir.c
index 18e59821c597..3015974fe2ff 100644
--- a/fs/erofs/dir.c
+++ b/fs/erofs/dir.c
@@ -22,11 +22,12 @@ static void debug_one_dentry(unsigned char d_type, const char *de_name,
 }
 
 static int erofs_fill_dentries(struct inode *dir, struct dir_context *ctx,
-			       void *dentry_blk, unsigned int *ofs,
+			       void *dentry_blk, void *dentry_begin,
 			       unsigned int nameoff, unsigned int maxsize)
 {
-	struct erofs_dirent *de = dentry_blk + *ofs;
+	struct erofs_dirent *de = dentry_begin;
 	const struct erofs_dirent *end = dentry_blk + nameoff;
+	loff_t begin_pos = ctx->pos;
 
 	while (de < end) {
 		const char *de_name;
@@ -59,9 +60,9 @@ static int erofs_fill_dentries(struct inode *dir, struct dir_context *ctx,
 			/* stopped by some reason */
 			return 1;
 		++de;
-		*ofs += sizeof(struct erofs_dirent);
+		ctx->pos += sizeof(struct erofs_dirent);
 	}
-	*ofs = maxsize;
+	ctx->pos = begin_pos + maxsize;
 	return 0;
 }
 
@@ -110,11 +111,9 @@ static int erofs_readdir(struct file *f, struct dir_context *ctx)
 				goto skip_this;
 		}
 
-		err = erofs_fill_dentries(dir, ctx, de, &ofs,
+		err = erofs_fill_dentries(dir, ctx, de, de + ofs,
 					  nameoff, maxsize);
 skip_this:
-		ctx->pos = blknr_to_addr(i) + ofs;
-
 		if (err)
 			break;
 		++i;
-- 
2.35.1