On Wed 04-08-21 12:06:03, Gabriel Krisman Bertazi wrote:
> Instead of failing, encode an invalid file handler in fanotify_encode_fh
> if no inode is provided. This bogus file handler will be reported by
> FAN_FS_ERROR for non-inode errors.
>
> Also adjust the single caller that might rely on failure after passing
> an empty inode.
It is not 'file handler' but rather 'file handle' - several times in the
changelog and in subject :).
> Suggested-by: Amir Goldstein <amir73il@xxxxxxxxx>
> Signed-off-by: Gabriel Krisman Bertazi <krisman@xxxxxxxxxxxxx>
> ---
> fs/notify/fanotify/fanotify.c | 39 ++++++++++++++++++++---------------
> fs/notify/fanotify/fanotify.h | 6 ++++--
> 2 files changed, 26 insertions(+), 19 deletions(-)
>
> diff --git a/fs/notify/fanotify/fanotify.c b/fs/notify/fanotify/fanotify.c
> index 0d6ba218bc01..456c60107d88 100644
> --- a/fs/notify/fanotify/fanotify.c
> +++ b/fs/notify/fanotify/fanotify.c
> @@ -349,12 +349,6 @@ static int fanotify_encode_fh(struct fanotify_fh *fh, struct inode *inode,
> void *buf = fh->buf;
> int err;
>
> - fh->type = FILEID_ROOT;
> - fh->len = 0;
> - fh->flags = 0;
> - if (!inode)
> - return 0;
> -
I'd keep the fh->flags initialization here. Otherwise it will not be
initialized on some error returns.
> @@ -363,8 +357,9 @@ static int fanotify_encode_fh(struct fanotify_fh *fh, struct inode *inode,
> if (fh_len < 4 || WARN_ON_ONCE(fh_len % 4))
> goto out_err;
>
> - /* No external buffer in a variable size allocated fh */
> - if (gfp && fh_len > FANOTIFY_INLINE_FH_LEN) {
> + fh->flags = 0;
> + /* No external buffer in a variable size allocated fh or null fh */
> + if (inode && gfp && fh_len > FANOTIFY_INLINE_FH_LEN) {
> /* Treat failure to allocate fh as failure to encode fh */
> err = -ENOMEM;
> ext_buf = kmalloc(fh_len, gfp);
> @@ -376,14 +371,24 @@ static int fanotify_encode_fh(struct fanotify_fh *fh, struct inode *inode,
> fh->flags |= FANOTIFY_FH_FLAG_EXT_BUF;
> }
>
> - dwords = fh_len >> 2;
> - type = exportfs_encode_inode_fh(inode, buf, &dwords, NULL);
> - err = -EINVAL;
> - if (!type || type == FILEID_INVALID || fh_len != dwords << 2)
> - goto out_err;
> -
> - fh->type = type;
> - fh->len = fh_len;
> + if (inode) {
> + dwords = fh_len >> 2;
> + type = exportfs_encode_inode_fh(inode, buf, &dwords, NULL);
> + err = -EINVAL;
> + if (!type || type == FILEID_INVALID || fh_len != dwords << 2)
> + goto out_err;
> + fh->type = type;
> + fh->len = fh_len;
> + } else {
> + /*
> + * Invalid FHs are used on FAN_FS_ERROR for errors not
> + * linked to any inode. Caller needs to guarantee the fh
> + * has at least FANOTIFY_NULL_FH_LEN bytes of space.
> + */
> + fh->type = FILEID_INVALID;
> + fh->len = FANOTIFY_NULL_FH_LEN;
> + memset(buf, 0, FANOTIFY_NULL_FH_LEN);
> + }
Maybe it will become clearer later during the series but why do you set
fh->len to FANOTIFY_NULL_FH_LEN and not 0?
Honza
--
Jan Kara <jack@xxxxxxxx>
SUSE Labs, CR
