Re: [PATCH v2] erofs: update ctx->pos for every emitted dirent

[Chao Yu]

On 2022/6/9 11:40, Hongnan Li wrote:

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...@linux.alibaba.com>
---
  fs/erofs/dir.c | 20 ++++++++++----------
  1 file changed, 10 insertions(+), 10 deletions(-)

diff --git a/fs/erofs/dir.c b/fs/erofs/dir.c
index 18e59821c597..94ef5287237a 100644
--- a/fs/erofs/dir.c
+++ b/fs/erofs/dir.c
@@ -22,10 +22,9 @@ 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, struct erofs_dirent *de,
                               unsigned int nameoff, unsigned int maxsize)
  {
-       struct erofs_dirent *de = dentry_blk + *ofs;
        const struct erofs_dirent *end = dentry_blk + nameoff;

while (de < end) {

@@ -59,9 +58,8 @@ 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;
        return 0;
  }

@@ -95,7 +93,7 @@ static int erofs_readdir(struct file *f, struct dir_context *ctx)

                                  "invalid de[0].nameoff %u @ nid %llu",
                                  nameoff, EROFS_I(dir)->nid);
                        err = -EFSCORRUPTED;
-                       goto skip_this;
+                       break;
                }

maxsize = min_t(unsigned int,

@@ -106,17 +104,19 @@ static int erofs_readdir(struct file *f, struct 
dir_context *ctx)
                        initial = false;

ofs = roundup(ofs, sizeof(struct erofs_dirent));

-                       if (ofs >= nameoff)
+                       if (ofs >= nameoff) {
+                               ctx->pos = blknr_to_addr(i) + ofs;
                                goto skip_this;
+                       }
                }

- err = erofs_fill_dentries(dir, ctx, de, &ofs,

-                                         nameoff, maxsize);
-skip_this:
                ctx->pos = blknr_to_addr(i) + ofs;

Why updating ctx->pos before erofs_fill_dentries()?

Thanks,

-
+               err = erofs_fill_dentries(dir, ctx, de, (void *)de + ofs,
+                                         nameoff, maxsize);
                if (err)
                        break;
+               ctx->pos = blknr_to_addr(i) + maxsize;
+skip_this:
                ++i;
                ofs = 0;
        }