The patch itself looks good to me.
On 6/29/22 4:15 PM, 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 <[email protected]>
> ---
> fs/erofs/dir.c | 16 +++++++---------
> 1 file changed, 7 insertions(+), 9 deletions(-)
>
> diff --git a/fs/erofs/dir.c b/fs/erofs/dir.c
> index 18e59821c597..6fc325052853 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 +104,17 @@ static int erofs_readdir(struct file *f, struct
> dir_context *ctx)
> initial = false;
>
> ofs = roundup(ofs, sizeof(struct erofs_dirent));
> + ctx->pos = blknr_to_addr(i) + ofs;
> if (ofs >= nameoff)
> goto skip_this;
Besides, I thinks there's another issue with erofs_readdir() here
(though unrelated to the issue this patch wants to fix).
We need to update ctx->pos correctly if the initial file position has
exceeded nameoff. ctx->pos needs to be updated to the end of
EROFS_BLKSIZ or directory's i_size, surpassing the remaining name string
in the current EROFS block.
> }
>
> - err = erofs_fill_dentries(dir, ctx, de, &ofs,
> + err = erofs_fill_dentries(dir, ctx, de, (void *)de + ofs,
> nameoff, maxsize);
> -skip_this:
> - ctx->pos = blknr_to_addr(i) + ofs;
> -
> if (err)
> break;
> + ctx->pos = blknr_to_addr(i) + maxsize;
It's quite easy to fix the above issue. We only need to move this line
beneath skip_this label.
> +skip_this:> ++i;
> ofs = 0;
> }
like:
skip_this:
ctx->pos = blknr_to_addr(i) + maxsize;
++i;
ofs = 0;
Thus we'd better fold this simple fix into this patch.
--
Thanks,
Jeffle
