Hi Jaegeuk, > -----Original Message----- > From: Jaegeuk Kim [mailto:[email protected]] > Sent: Thursday, July 16, 2015 6:38 AM > To: [email protected]; [email protected]; > [email protected] > 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 <[email protected]> > --- > 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 > > > ------------------------------------------------------------------------------ > Don't Limit Your Business. Reach for the Cloud. > GigeNET's Cloud Solutions provide you with the tools and support that > you need to offload your IT needs and focus on growing your business. > Configured For All Businesses. Start Your Cloud Today. > https://www.gigenetcloud.com/ > _______________________________________________ > Linux-f2fs-devel mailing list > [email protected] > https://lists.sourceforge.net/lists/listinfo/linux-f2fs-devel -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [email protected] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
