On Fri, Oct 15, 2021 at 12:39 AM Gabriel Krisman Bertazi
<krisman@xxxxxxxxxxxxx> wrote:
>
> Plumb the pieces to add a FID report to error records. Since all error
> event memory must be pre-allocated, we pre-allocate the maximum file
> handle size possible, such that it should always fit.
>
> For errors that don't expose a file handle report it with an invalid
> FID.
>
> Signed-off-by: Gabriel Krisman Bertazi <krisman@xxxxxxxxxxxxx>
>
> ---
> Changes since v6:
> - pass fsid from handle_events
> Changes since v5:
> - Use preallocated MAX_HANDLE_SZ FH buffer
> - Report superblock errors with a zerolength INVALID FID (jan, amir)
> ---
> fs/notify/fanotify/fanotify.c | 15 +++++++++++++++
> fs/notify/fanotify/fanotify.h | 8 ++++++++
> 2 files changed, 23 insertions(+)
>
> diff --git a/fs/notify/fanotify/fanotify.c b/fs/notify/fanotify/fanotify.c
> index 7032083df62a..8a60c96f5fb2 100644
> --- a/fs/notify/fanotify/fanotify.c
> +++ b/fs/notify/fanotify/fanotify.c
> @@ -611,7 +611,9 @@ static struct fanotify_event *fanotify_alloc_error_event(
> {
> struct fs_error_report *report =
> fsnotify_data_error_report(data, data_type);
> + struct inode *inode = report->inode;
> struct fanotify_error_event *fee;
> + int fh_len;
>
> if (WARN_ON(!report))
> return NULL;
> @@ -622,6 +624,19 @@ static struct fanotify_event *fanotify_alloc_error_event(
>
> fee->fae.type = FANOTIFY_EVENT_TYPE_FS_ERROR;
> fee->err_count = 1;
> + fee->fsid = *fsid;
> +
> + fh_len = fanotify_encode_fh_len(inode);
> + if (WARN_ON(fh_len > MAX_HANDLE_SZ)) {
WARN_ON_ONCE please and I rather that this sanity check is moved inside
fanotify_encode_fh_len() where it will return 0 for encoding failure.
> + /*
> + * Fallback to reporting the error against the super
> + * block. It should never happen.
> + */
> + inode = NULL;
> + fh_len = fanotify_encode_fh_len(NULL);
> + }
> +
> + fanotify_encode_fh(&fee->object_fh, inode, fh_len, NULL, 0);
>
> *hash ^= fanotify_hash_fsid(fsid);
>
> diff --git a/fs/notify/fanotify/fanotify.h b/fs/notify/fanotify/fanotify.h
> index 2b032b79d5b0..b58400926f92 100644
> --- a/fs/notify/fanotify/fanotify.h
> +++ b/fs/notify/fanotify/fanotify.h
> @@ -202,6 +202,10 @@ struct fanotify_error_event {
> u32 err_count; /* Suppressed errors count */
>
> __kernel_fsid_t fsid; /* FSID this error refers to. */
> + /* object_fh must be followed by the inline handle buffer. */
> + struct fanotify_fh object_fh;
> + /* Reserve space in object_fh.buf[] - access with fanotify_fh_buf() */
> + unsigned char _inline_fh_buf[MAX_HANDLE_SZ];
> };
This struct duplicates most of struct fanotify_fid_event.
How about:
#define FANOTIFY_ERROR_FH_LEN \
(MAX_HANDLE_SZ - FANOTIFY_INLINE_FH_LEN)
struct fanotify_error_event {
u32 err_count; /* Suppressed errors count */
struct fanotify_event ffe;
/* Reserve space in ffe.object_fh.buf[] - access with
fanotify_fh_buf() */
unsigned char _fh_buf[FANOTIFY_ERROR_FH_LEN];
}
Or leaving out the struct padding and passing
FANOTIFY_ERROR_EVENT_SIZE as mempool object size?
#define FANOTIFY_ERROR_EVENT_SIZE \
(sizeof(struct fanotify_error_event) + FANOTIFY_ERROR_FH_LEN)
You do not have to make this change - it is a proposal that can have
supporters and objectors, so let's wait to see what you and other reviewers
have to say.
Thanks,
Amir.
