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AJvYcCUCOq6Le/Q98MQCbysHT79bZyJgCK6vCrjkjJdF2DicvSKHin6aqyfiPUT/f1ITHaOlJg39qx+/IMbKdMWJSg==@vger.kernel.org, AJvYcCXp3kyNZ/SCf/OhMmtRw0TSQjdhTqjxRwd7C31FnL9p7suMmAkezh7LAlNOKrb0zZjR8jXPIuTtWnXWi5nB@vger.kernel.org X-Gm-Message-State: AOJu0YyyN9zv4tRsynsoXgfUHQQtRGarlzc9ojYewfZmI/LuVPTofdMg Qn3fEkoaVv8uHNiGmH5OLbCR8L+ZVTVaQthXxei0W5yU6unceANwPbnXOiZcG82egjzu17TPW/E YWsCaEjZ8d2cvOw4SMujnRij3r1I= X-Google-Smtp-Source: AGHT+IHxVbejksjkiJ4bu5X2Ujh1lTVoUGRd+56TnkwW6xTiLkIucqmZ/ltp7xCCNHFuo2XUINNMW+1Qag84iz0XD6Y= X-Received: by 2002:a05:620a:46a6:b0:7ac:b1b1:e730 with SMTP id af79cd13be357-7b11a3b8e7dmr864974785a.61.1728721549070; Sat, 12 Oct 2024 01:25:49 -0700 (PDT) Precedence: bulk X-Mailing-List: linux-unionfs@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 References: <20241011-work-overlayfs-v2-0-1b43328c5a31@kernel.org> <20241011-work-overlayfs-v2-2-1b43328c5a31@kernel.org> In-Reply-To: <20241011-work-overlayfs-v2-2-1b43328c5a31@kernel.org> From: Amir Goldstein Date: Sat, 12 Oct 2024 10:25:38 +0200 Message-ID: Subject: Re: [PATCH RFC v2 2/4] ovl: specify layers via file descriptors To: Christian Brauner Cc: Miklos Szeredi , Josef Bacik , linux-fsdevel@vger.kernel.org, linux-unionfs@vger.kernel.org Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: quoted-printable On Fri, Oct 11, 2024 at 11:46=E2=80=AFPM Christian Brauner wrote: > nit: if you can avoid using the exact same title for the cover letter and a patch that would be nice (gmail client collapses them together). > Currently overlayfs only allows specifying layers through path names. > This is inconvenient for users such as systemd that want to assemble an > overlayfs mount purely based on file descriptors. > > This enables user to specify both: > > fsconfig(fd_overlay, FSCONFIG_SET_FD, "upperdir+", NULL, fd_upper); > fsconfig(fd_overlay, FSCONFIG_SET_FD, "workdir+", NULL, fd_work); > fsconfig(fd_overlay, FSCONFIG_SET_FD, "lowerdir+", NULL, fd_lower1); > fsconfig(fd_overlay, FSCONFIG_SET_FD, "lowerdir+", NULL, fd_lower2); > > in addition to: > > fsconfig(fd_overlay, FSCONFIG_SET_STRING, "upperdir+", "/upper", 0); > fsconfig(fd_overlay, FSCONFIG_SET_STRING, "workdir+", "/work", 0); > fsconfig(fd_overlay, FSCONFIG_SET_STRING, "lowerdir+", "/lower1", 0); > fsconfig(fd_overlay, FSCONFIG_SET_STRING, "lowerdir+", "/lower2", 0); > Please add a minimal example with FSCONFIG_SET_FD to overlayfs.rst. I am not looking for a user manual, just one example to complement the FSCONFIG_SET_STRING examples. I don't mind adding config types on a per need basis, but out of curiosity do you think the need will arise to support FSCONFIG_SET_PATH{,_EMPTY} in the future? It is going to be any more challenging than just adding support for just FSCONFIG_SET_FD? Again, not asking you to do extra work for a feature that no user asked for= . Other than that, it looks very nice and useful. Thanks, Amir.