Re: [PATCH 1/3] hfs: add missing clean-up in hfs_fill_super

[Desmond Cheong Zhi Xi]

On 30/6/21 3:13 am, Viacheslav Dubeyko wrote:
> > On Jun 29, 2021, at 7:48 AM, Desmond Cheong Zhi Xi <desmondcheongzx@xxxxxxxxx> wrote:
> >
> > On exiting hfs_fill_super, the file descriptor used in hfs_find_init
> > should be passed to hfs_find_exit to be cleaned up, and to release the
> > lock held on the btree.
> >
> > The call to hfs_find_exit is missing from this error path, so we add
> > it in to release resources.
> >
> > Signed-off-by: Desmond Cheong Zhi Xi <desmondcheongzx@xxxxxxxxx>
> > ---
> > fs/hfs/super.c | 1 +
> > 1 file changed, 1 insertion(+)
> >
> > diff --git a/fs/hfs/super.c b/fs/hfs/super.c
> > index 44d07c9e3a7f..48340b77eb36 100644
> > --- a/fs/hfs/super.c
> > +++ b/fs/hfs/super.c
> > @@ -419,6 +419,7 @@ static int hfs_fill_super(struct super_block *sb, void *data, int silent)
> > 	res = hfs_cat_find_brec(sb, HFS_ROOT_CNID, &fd);
> > 	if (!res) {
> > 		if (fd.entrylength > sizeof(rec) || fd.entrylength < 0) {
> > +			hfs_find_exit(&fd);
>
> I see that there are several places of hfs_find_exit() calls in hfs_fill_super(). Maybe, it makes sense to move the hfs_find_exit() call to the end of the hfs_fill_super()? In this case we could process this activity of resources freeing into one place. I mean line 449 in the source code (failure case).
>
> Thanks,
> Slava.
>
> > 			res =  -EIO;
> > 			goto bail;
> > 		}
> > --
> > 2.25.1

Thanks for the suggestion. Since the bail and bail_no_root error paths 
are used before hfs_find_init and after hfs_find_exit are called in the 
normal execution case, moving hfs_find_exit under the bail label 
wouldn't work.

Perhaps this can be done by introducing another goto label. Any thoughts 
on the following?

diff --git a/fs/hfs/super.c b/fs/hfs/super.c
index 44d07c9e3a7f..12d9bae39363 100644
--- a/fs/hfs/super.c
+++ b/fs/hfs/super.c
@@ -420,14 +420,12 @@ static int hfs_fill_super(struct super_block *sb, 
void *data, int silent)
        if (!res) {
                if (fd.entrylength > sizeof(rec) || fd.entrylength < 0) {
                        res =  -EIO;
-                       goto bail;
+                       goto bail_hfs_find;
                }
                hfs_bnode_read(fd.bnode, &rec, fd.entryoffset, 
fd.entrylength);
        }
-       if (res) {
-               hfs_find_exit(&fd);
-               goto bail_no_root;
-       }
+       if (res)
+               goto bail_hfs_find;
        res = -EINVAL;
        root_inode = hfs_iget(sb, &fd.search_key->cat, &rec);
        hfs_find_exit(&fd);
@@ -443,6 +441,8 @@ static int hfs_fill_super(struct super_block *sb, 
void *data, int silent)
        /* everything's okay */
        return 0;

+bail_hfs_find:
+       hfs_find_exit(&fd);
 bail_no_root:
        pr_err("get root inode failed\n");
 bail: