On Thu, Jun 18, 2020 at 6:44 PM Amir Goldstein <amir73il@xxxxxxxxx> wrote:
>
> The check if user has changed the overlay file was wrong, causing unneeded
> call to ovl_change_flags() including taking f_lock on every file access.
>
> Fixes: d989903058a8 ("ovl: do not generate duplicate fsnotify events...")
> Cc: <stable@xxxxxxxxxxxxxxx> # v4.19+
> Signed-off-by: Amir Goldstein <amir73il@xxxxxxxxx>
> ---
> fs/overlayfs/file.c | 10 ++++++----
> 1 file changed, 6 insertions(+), 4 deletions(-)
>
> diff --git a/fs/overlayfs/file.c b/fs/overlayfs/file.c
> index 01820e654a21..0d940e29d62b 100644
> --- a/fs/overlayfs/file.c
> +++ b/fs/overlayfs/file.c
> @@ -33,13 +33,16 @@ static char ovl_whatisit(struct inode *inode, struct inode *realinode)
> return 'm';
> }
>
> +/* No atime modificaton nor notify on underlying */
> +#define OVL_OPEN_FLAGS (O_NOATIME | FMODE_NONOTIFY)
> +
> static struct file *ovl_open_realfile(const struct file *file,
> struct inode *realinode)
> {
> struct inode *inode = file_inode(file);
> struct file *realfile;
> const struct cred *old_cred;
> - int flags = file->f_flags | O_NOATIME | FMODE_NONOTIFY;
> + int flags = file->f_flags | OVL_OPEN_FLAGS;
> int acc_mode = ACC_MODE(flags);
> int err;
>
> @@ -72,8 +75,7 @@ static int ovl_change_flags(struct file *file, unsigned int flags)
> struct inode *inode = file_inode(file);
> int err;
>
> - /* No atime modificaton on underlying */
> - flags |= O_NOATIME | FMODE_NONOTIFY;
> + flags |= OVL_OPEN_FLAGS;
>
> /* If some flag changed that cannot be changed then something's amiss */
> if (WARN_ON((file->f_flags ^ flags) & ~OVL_SETFL_MASK))
> @@ -126,7 +128,7 @@ static int ovl_real_fdget_meta(const struct file *file, struct fd *real,
> }
>
> /* Did the flags change since open? */
> - if (unlikely((file->f_flags ^ real->file->f_flags) & ~O_NOATIME))
> + if (unlikely((file->f_flags ^ real->file->f_flags) & ~OVL_OPEN_FLAGS))
> return ovl_change_flags(real->file, file->f_flags);
>
> return 0;
> --
> 2.17.1
>
Miklos,
Was this patch left out intentionally?
Thanks,
Amir.
