Hi Jaegeuk,
> -----Original Message-----
> From: Jaegeuk Kim [mailto:jaeg...@kernel.org]
> Sent: Thursday, July 16, 2015 6:38 AM
> To: linux-ker...@vger.kernel.org; linux-fsde...@vger.kernel.org;
> linux-f2fs-devel@lists.sourceforge.net
> Cc: Jaegeuk Kim
> Subject: [f2fs-dev] [PATCH 3/3] f2fs: allow zeroed name length during
> find_dentry
>
> Since find_dentry doesn't lock its dentry page, it can traverse intermediate
> bit positions consisting of a big dentry.
> For these bit positions, this patch fills the intermediate name length fields
> as zeros and skips them during look-up.
I didn't get it, AFAIK, dentry page will be accessed under protection of
i_mutex, if our inode operation has no bug, why this zeroed name_len can
exist?
Thanks,
>
> Signed-off-by: Jaegeuk Kim <jaeg...@kernel.org>
> ---
> fs/f2fs/dir.c | 20 ++++++++++++++------
> 1 file changed, 14 insertions(+), 6 deletions(-)
>
> diff --git a/fs/f2fs/dir.c b/fs/f2fs/dir.c
> index a34ebd8..71195f5 100644
> --- a/fs/f2fs/dir.c
> +++ b/fs/f2fs/dir.c
> @@ -141,11 +141,15 @@ struct f2fs_dir_entry *find_target_dentry(struct
> f2fs_filename *fname,
> *max_slots = max_len;
> max_len = 0;
>
> - /* remain bug on condition */
> - if (unlikely(!de->name_len))
> - d->max = -1;
> -
> - bit_pos += GET_DENTRY_SLOTS(le16_to_cpu(de->name_len));
> + /*
> + * While a large dentry is adding, it can traverse its valid bit
> + * positions, since find_entry does not lock its dentry page.
> + * In that case, let's skip the bit position.
> + */
> + if (de_name.len == 0)
> + bit_pos++;
> + else
> + bit_pos += GET_DENTRY_SLOTS(de_name.len);
> }
>
> de = NULL;
> @@ -505,8 +509,12 @@ void f2fs_update_dentry(nid_t ino, umode_t mode, struct
> f2fs_dentry_ptr
> *d,
> memcpy(d->filename[bit_pos], name->name, name->len);
> de->ino = cpu_to_le32(ino);
> set_de_type(de, mode);
> - for (i = 0; i < slots; i++)
> + for (i = 0; i < slots; i++) {
> + /* fill zeros for intermediate name_len slots */
> + if (i >= 1)
> + d->dentry[bit_pos + i].name_len = 0;
> test_and_set_bit_le(bit_pos + i, (void *)d->bitmap);
> + }
> }
>
> /*
> --
> 2.1.1
>
>
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