fanotify: distinguish between fid encode error and null fid

In fanotify_encode_fh(), both cases of NULL inode and failure to encode
ended up with fh type FILEID_INVALID.

Distiguish the case of NULL inode, by setting fh type to FILEID_ROOT.
This is just a semantic difference at this point.

Remove stale comment and unneeded check from fid event compare helpers.

Link: https://lore.kernel.org/r/20200716084230.30611-4-amir73il@gmail.com
Signed-off-by: Amir Goldstein <amir73il@gmail.com>
Signed-off-by: Jan Kara <jack@suse.cz>

diff --git a/fs/notify/fanotify/fanotify.c b/fs/notify/fanotify/fanotify.c
index 84c86a45874c48ae00510a6a1252fb0e983f80ad..3dc71a8e795ab69cf259ea645bf5d31bc4e9fab7 100644 (file)
--- a/fs/notify/fanotify/fanotify.c
+++ b/fs/notify/fanotify/fanotify.c
@@ -34,10 +34,6 @@ static bool fanotify_fh_equal(struct fanotify_fh *fh1,
        if (fh1->type != fh2->type || fh1->len != fh2->len)
                return false;
 
-       /* Do not merge events if we failed to encode fh */
-       if (fh1->type == FILEID_INVALID)
-               return false;
-
        return !fh1->len ||
                !memcmp(fanotify_fh_buf(fh1), fanotify_fh_buf(fh2), fh1->len);
 }
@@ -56,10 +52,7 @@ static bool fanotify_fid_event_equal(struct fanotify_fid_event *ffe1,
 static bool fanotify_name_event_equal(struct fanotify_name_event *fne1,
                                      struct fanotify_name_event *fne2)
 {
-       /*
-        * Do not merge name events without dir fh.
-        * FAN_DIR_MODIFY does not encode object fh, so it may be empty.
-        */
+       /* Do not merge name events without dir fh */
        if (!fne1->dir_fh.len)
                return false;
 
@@ -290,8 +283,10 @@ static void fanotify_encode_fh(struct fanotify_fh *fh, struct inode *inode,
        void *buf = fh->buf;
        int err;
 
+       fh->type = FILEID_ROOT;
+       fh->len = 0;
        if (!inode)
-               goto out;
+               return;
 
        dwords = 0;
        err = -ENOENT;
@@ -326,7 +321,6 @@ out_err:
                            type, bytes, err);
        kfree(ext_buf);
        *fanotify_fh_ext_buf_ptr(fh) = NULL;
-out:
        /* Report the event without a file identifier on encode error */
        fh->type = FILEID_INVALID;
        fh->len = 0;